A fellow member I know has told me he has a NOS 3.55 gear set for a 36 truck. I have been told the truck, and master in 36 used the same differential. He also has a differential out of a 54 powerglide car. I have seen a post on the web site about converting the differential to the later style 3.73. My question is two fold - doesn't the later style look significantly different being a hypoid style, and how difficult is it to change the gear set in the original 36? Any challenges? This is a fairly high point car.

If it is a "high point car" then why change it? I enjoy my two 1936's as is, original.

maybe he likes higher speed driving turning a whole lot less RPM.
Also would get better gas mileage with 3.55 as motor is not turning over as fast.

Longer engine life due to less stress of tighter rpm.

mike

A 3.55 ring gear was never made for a 1936 truck or car. I would question that one.
The differential for 1937 and up cars is completely different and comes with the torque tube so length can be a problem
Anything can be dome with a lot of machening and tools.
There was a optional 3.82 made for 1935 and 1936 Masters. Very rare.
A 3,82. or 3.73 would reduce your RPM,s from 7 to 10 percent. 10 percent with the 3.73 would gain you 5 MPH at 50 MPH.
If the engines are in good condition then can be driven at at least 55 MPH......going 60 wwith a 3.73 will be very little gain and traffic will still be flying by a 70 + MPH.

If you can ever get up to 70 with the original stuff, I would like to hear about that one. At 60 it should start to "get light" and go air born. On coming traffic on a two lane U. S. Highway passing would cause the car to rock, especially a semi rig. The air blast would hit the car hard.
Who would want to go that fast? Just plain scary and dangerous to exceed the car's design. Not that I haven't been above 60 but in my younger days and only for a short while. A sustained 60+ driving any distance is ill advised. (The most Dad ever drove on the open highway was 55 and up to 60 in short bursts. Then back to 55.) I do not go on the Inter State Highway. 45 and 50 is more like it for this type of vehicle.

Remember the higher the gears the less power you have.

I agree with the above with one minor exception. You will find that the Master with knee-action is much more stable feeling at high speeds.....and if in good shape will hit 75 on the speedometer.....and 55 to 60 is a comfortable crusing speed after you get accustom to driving an old car.

Beach,

As this article demonstrates the project you are contemplating is easily accomplished in a home shop that has basic machining and welding equipment:

https://vccachat.org/ubbthreads.php/topics/334876/1936_Chevy_3.55_rear_gear_conv

It will have no effect on the "high point" status of the car because once completed it looks original. The judges simply aren't knowledgeable enough or energetic enough to crawl under your vehicle and say "Ah ha, that's a hypoid differential, not a spiral bevel differential. You're caught buddy".

I know from personal experience that the judges won't catch it. My '36 PU won Class T-2 at the 1976 VCCA National Meet with obvious safety upgrades like modern tie rod ends on the tie rod and a home made drag link with those same modern tie rod ends. Those modifications, made to eliminate steering linkage slack, went unrecognized.

If you'd appreciate less engine noise and a 17% drop in RPM/increase in cruising speed there's no reason not to go for it. My '36 pulls the 3.55 gears easily with no engine modifications except a rejetted '39-'40 carburetor and a paper element in the air filter.

Ray W

All 1936 Trucks are straight axle. So no riding like a Master Car. More like riding in a diesel 18 wheeler.

The pick-up truck and even the Standard passenger cars are a few hundred pounds lighter than a Master sedan so the "high speed gears" would limit the acceleration and hill climbing power in a Master.

There was another member at the recent NW meet who has the 3:55 gear set in his 36 master coupe. He said it made a lot of difference in the driveability of his car. I am still in the investigation stage, we will see.

How did he do it? Did he use Ray W's method?

I have a 36 Pontiac, and it uses the same differential as a 36 master. I have been down this rabbit hole in every way possible, and I am fairly sure no 3.55 ring and pinion sets were ever made for this differential. I would absolutely love to be proven wrong.

To the best of my knowledge, Ray W's method is by far the cheapest and least invasive way to get 3.55.

If you can find out how that guy at the NW meet did it, please let us know!

The 1936 Pontiac 6 had a 4.44 ratio and the 8 had a 4,55.
The 4.11 from a Chevrolet would already be an improvement.

Gene- Thanks to a very helpful forum member, I am building a 3.82 third member. My Pontiac has the optional 4.88 gears (the 4.11 Chevy gears were also optional). It is a six, and yes if it had the standard setup it would be 4.44.

Have you ever actually seen 4.55? My shop manual says the Pontiac Eight is 4.55, but I have come to suspect it is a typo. I have never (yet) seen any part number for a 4.55 ring and pinion.

SEEN guys down here jump on the freeway and hit 75/80 MPH! THEY ARE MOVING! very unsafe on So. Cal freeways
for me 45/50 mph at the most

"All 1936 Trucks are straight axle. So no riding like a Master Car. More like riding in a diesel 18 wheeler."

That's a fact Terrill. I've had that '36 since I was a 20 year old college kid in 1965 and now at age nearly 73 I still love driving around in it. It's bouncy even with optional shock absorbers. And the multipiece cab sheet metal nailed to a wood frame squeaks like a haunted house on the bumpy country roads around where I live. I love it and wouldn't change a thing.

If I wanted a Lexus I'd get one. Grin!


"To the best of my knowledge, Ray W's method is by far the cheapest and least invasive way to get 3.55."

Bloo,

I think you would be impressed with how totally original is looks. I can say with confidence that even if I pointed it out to you you'd say "Really". Let me know if you'd like to see a photo.

It would be really easy to do another now that I've done the job once.

"The pick-up truck and even the Standard passenger cars are a few hundred pounds lighter than a Master sedan so the "high speed gears" would limit the acceleration and hill climbing power in a Master."

Gene,

There is an 11% grade near my home a couple of miles long. With the 3.55 gears my '36 won't pull that hill in 3rd gear but it pulls it easily in 2nd. Even with 4.11 gears my '36 couldn't pull that hill in 3rd. Now that I've run the same '36 with both gear ratios the 3.55 gears seem better in every way. If this were 1936 and I was hauling loads that might not be the case. Today it hauls only a cooler and a couple of lawn chairs.

Ray W

I have had my 1936 truck since 1964 some 53 years. I am the second owner. I am 70 years old and also would not change a thing about this bouncy old gal. She has overload springs and can still haul a one thousand pound load over these hills on dirt roads out here in rural Mississippi. Yes, I use second gear to pull 11% grades. She is not fast but still a very good truck.

"Yes, I use second gear to pull 11% grades."

3 speed or 4 speed "crash" box? Mine's a 3-speed. If yours is too I found the perfect equivalent of the 160 gear oil recommended back in the day. It's a Lubriplate product, not the "600W" steam cylinder oil sold by some vendors.

I'll send you an emailed PM.

Ray W

The 1938 Pontiac parts book list ring gear and pinion set, 544266, 4.55 ratio for a a '35 P/8 after axle number 8-1452022 and all '36 P/8.
Also the 1934 P8 and early 1935 P8 had a 4.55 but the change was to the roller bearing in mid 1935...same change made to the Chevrolet differential.

Ray, Going by my 1939 the change from the 4.22 that would pull any hill in high gear to a 3,73 didn't kill the power too much with just the driver but with 4 people in the car the speed would drop off on larger hills requiring the use of 2nd gear.Empty the '39 was a couple hundred of pounds lighter than a '36 Master and the 216 developed more torque.
With the 3.73 it would cruise smooth and quiet at 70 MPH.

I've just read through this thread and found it interesting. Gene has pointed out all the things one would need to know before attempting a change of differential gearing. For instance:

a. As you lower (you know go to taller gears) the engine will turn over less for the miles driven.

b. There is a trade off with the above gears. The taller the gears the less hill and highspeed power you will have. That is to say you will experience what is called deminishing return or trade off. The engine will suffer pulling power the taller the gear.

c. If you go to taller gears then you will need to increase the horsepower in direct coorelation to the gear ratio to engine horsepower.

d. As I understand it a 1950 Frod without overdrive will run at top speed about equal to the one with O/D. The slight difference owing to the speed and direction of the wind the vehicle is going through.

If one wants a good performing old Chevrolet then don't screw with the product as manufactured. If you don't then one thing will lead to another. A 1941 with the 4:11 is a good all-around gear. It premits good level travel whild having good incling climbing power and engine braking assist.

We always want to tinker and try to outdo the factory engineers, but they were and are smarter than most of us. So I believe.

Just my two cents worth.

Charlie

BTW: The old saying about doubling the speed of an airplane was that you had to quadruple the horsepower. Interesting, huh?

Charlie have you considered that the environment the cars are now running in are much different than when the engineers designed them? You are correct that they were very smart however they did not have a crystal ball and know the conditions in which they are now being driven or the products available to maintain them.

Thanks. Always good to have somewhere else to get products. I use Case International Harvester products on mine.

"Gene has pointed out all the things one would need to know before attempting a change of differential gearing."

Charlie,

This is not a hypothetical for me. I've actually done that 4.11 to 3.55 conversion and I can enthusiastically recommend it to anyone. The bone stock 207 engine pulls the 3.55 gears no sweat and the reduced engine noise and more comfortable highway running are huge pluses.

A '37 car rear end, 3.55 gears and access to a lathe and welder are all it takes.

Ray W

I owned my '35 Std coupe for 43 years, and have driven it
every where, including on the Interstates! The stock 4:11
rear axle is adequate for most driving situations. I have had
her up to 60 mph, but not held for long! On Interstate driving
I usually cruise comfortably at 50 mph. The minimum speed on
most Interstates is 40 mph, and at 50 the car cruises easily
and within safe braking limitations! I wouldn't put too much
faith in those brakes at higher speeds! I don't feel I have
ever been a hazard to faster moving traffic, but there is
always the idiot who will cut you short when passing! The joy
of driving an antique is staying within its limitations!

Thanks!

Also, I think the 4:88 kept the old bearing right up to the end. One parts book I found online said 1936 4:88 used a ball bearing instead of the Hyatt. I suspect it is the same one used in 1934 to early 1935.

Do you know if the any of the machining changed on the case when they changed to the new bearing?

In other words, can you put the 34-to-early-35 pinion in a late-35-to-36 housing (or vice versa) as long as you use the correct bearing for the pinion?

Yes, I would love to see a photo. I did see the photos, before they disappeared, and I thought I saved them, but I am not finding them now.

This isn't the road I am currently going down, as I have a 3.82 ring and pinion.

I researched and read about this every way I could, including your method, or an aftermarket 3.55 ring and pinion (you know why this one wont work), Mitchell overdrives, Borg Warner overdrives in the torque tube (as seen in model A and Buick circles), Laycock aka Gear vendors overdrives, The possibility of a Jeep or Studebaker top shifter plate on a rambler t86 with overdrive, Warner T5s, and a few other things... I could go on about this subject for hours.

I wanted to not change it too much, but the 4.88 is ridiculous. If I successfully get this 3.82 built I can just change the center section with the torque tube and be done. Most people don't have the option of doing this, as the 3.82 is rare as hens teeth. I do wish it was higher. Also the 36 axle is expensive to rebuild, and likely to be all screwed up when you look inside. I suspect you know all this....

I was looking for a 1937 housing to modify like yours until i got the 3.82. It is possibly a little more involved than what you did because the Pontiac has Bendix brakes instead of Huck. They made a change in mid 36 in the way the backing plates attach to the axle housing I'm guessing one of the two types would just fit the 37 Chevrolet housing, but Im not sure. Regardless, none of this is insurmountable anyway as I have access to a lathe and a mill here.

What is the the center to center distance between your 36 truck rear leafs? I know you had to move them in on the 37 housing.

"This isn't the road I am currently going down, as I have a 3.82 ring and pinion."

Bloo,

It is my understanding that the 3.82 factory "economy" gearset is not a bolt in because the 3.82 ring gear requires a unique differential case that is also extraordinarily rare. In the 52 years I've owned my '36 I've never seen a 3.82 gear set nor the required differential case offered for sale. Also, there is the question of how much of a gear change you want. Will a 3.82 get you there?

"I researched and read about this every way I could, including your method, or an aftermarket 3.55 ring and pinion (you know why this one wont work), Mitchell overdrives, Borg Warner overdrives in the torque tube (as seen in model A and Buick circles), Laycock aka Gear vendors overdrives, The possibility of a Jeep or Studebaker top shifter plate on a rambler t86 with overdrive, Warner T5s, and a few other things... I could go on about this subject for hours."

Yes, there are certainly many ways to approach this task. Here's another; years ago I met a guy who had grafted a Volvo OD into the torque tube of his Model A Ford. He said that the stock engine pulled the A at freeway speeds with no bogging problems. It gave him the option of 6 forward speeds but was an obvious modification,

I'm away from home for a few days but I'll be glad to send to the measurements between '36 spring perches. I saved the original rear axle so it's no sweat to get that dimension. If you don't hear from me within about 5 days please remind me. There is the risk of a possible "senior moment" that I usually deal with by doing stuff "right now" but that's not an option until next Wednesday.

I will look to see if the photos are saved anyplace except in the article. If not will the whole article, with photos, work for you?

I'm really glad you found the information in my article interesting.

Ray W

I used to think so, but after poring over the parts book until my eyes crossed, I now think that it is the 3.82 gears for the Chevrolet Standard that require a special differential case. As I'm sure you know, the Standard is a whole different rear axle.

I now believe the 3.82 gears for the Master and 1/2 ton use the same differential case as the 4.11 (and probably all the others). So, when the gears were offered, I jumped. I really should mock it up and see as I have the 3.82 gears in my possession.

Interestingly, the only piece I am currently missing is the differential case. Both of the ones I have are damaged.


I dont know.

I wanted more. It is fairly easy to calculate how to get to what rpm at 60 you might like, but then will the engine pull it? My best guess was 3.55, for a whole bunch of reasons, including things you have posted elsewhere, as well as the fact that all the aftermarket gears for the Chevy sixes with hypoid axles are 3.55. Larry Jackson made some sets of about 3.32 or so for the 36 rearend. Not very many. He isn't making any more. I would be willing to try it, but you cant get it. I hear those worked out well, but it does sound a bit high. My tires are 600-16.

The short answer is 3.82 is the highest thing that I could get for this axle.

The Pontiac engine is a 208ci flathead with precision insert bearings and full pressure oiling. In theory it should survive being wound up longer than the 207ci Chevrolet. Maybe 3.82 will be enough. It is so difficult to judge how much torque the engine has because the gears are so low. On the highway it will gain speed on any hill in high gear, no matter how steep. I have only had it to 53mph though. It would go faster, but it is just screaming at 53.


Yes, thank you! From the article (how far the springs mounts were moved) I should also be able to extrapolate what that distance was on the 37. I am not in a hurry for this information as I doubt I will be able to tackle this project again until early winter.

1935 Standard 3.82 ring gear and pinion part #601749. requires use of 601755 case.

1936 Standard 3.82 ring gear and pinion #602044 requires caes # 602031.

Late 1935 and all 1936 Master and late 1935 and all 1936 1/2 ton trucks ring ggear and pinion (3.82) 602477 existing case is used. Special case not required.

The case (part ring gear attaches to) is different for the Standard models due to the pinion gear being larger in diameter and would contact the housing. The case from a 4.11 would work but material would need to be removed in the area the ring gear attachw=es to to bring the ring gear away from the carrier.

The Master hosing has enough room on the sides so the case change is not necessary.

The same is true when a 3.55 is installed n a 1940-1954 rear end that had a 4.11 ratio.

The 3.82 will reduce the 3000 RPM at 60 MPH to about 2800 RPM.

The 1936 Pontiac uses case #602276 for a 4.11 and I do not see ths number for Chevrolet. Actually the Pontiac case is different for each of the three ratios Pontiac used.

My two cents:
Any gears lower than 3:55 (higher numbers) is not enough return for the effort. As Gene and others mentioned, 3:73 is still gonna rev pretty high RPMs.
Also consider the rear tire height can be changed with different tire manufacturers will help to deal with the gears you already have. Any way you decide to go will be an improvement. Most important is lowering the RPMs for preservation of our precious engines. The reward when we accomplish what people say can't be done is pretty cool too.

I should have mentioned that ring gear and pinion # 602477 was also used for 1937-1939 1/2 ton trucks when a 3.82 ratio is desired.

I would say a ratio like 3.73 is ideal for replacing a 4.11. It reduces engine speed by 10 percent which doesn't sound like much but makes for a dramatic change for highway driving.
With a 216 engine it makes 65 MPH a confortable driving speed with the engine turning less than 3000 RPM.
If it was available for a 207 engine 60 would be a comfortable speed with less than 2800 RPM.
At any of the above speeds you will still look like a turtle when driving on a freeway or interstate.

To add another reference point I am very pleased with the overall performance of my '37 Master coupe with a 3.73 axle.

Most of my driving is around town with a lot of stop and go. It accelerates well enough to keep up with traffic. I do drive some portions of the interstate within the area and 65 is not a problem although it gets pretty noisy. It really runs well and is enjoyable to drive at 55 to 60 on the 2 lane roads.

My 207 engine in 3rd in overdrive gives me around 3:25 gears (4:11 rear) on the highway. I just think 3:73 would be minimal.

Thanks for the responses everyone!


I did not know that. Could those numbers be with the ring already riveted on? The "parts book" Early Times Chapter (Pontiac) has posted shows 364538 (like a Chevy) for all 1935-36. I don't think it is an original book, so it could be wrong, I guess the implication is that the differential case will have to come from a Chevrolet. That isn't a huge stumbling block as both of my Pontiac ones are bad.

http://chevy.oldcarmanualproject.com/parts/1929_54/351.htm

https://web.archive.org/web/20170317194133/http://www.earlytimeschapter.org/documents/1935-36_parts_book.pdf

You know I have 4.88 right now, right? It will definitely be a noticeable change. Yes, it still sounds too low. I love this car, but it's too slow to take out of town.

I may need to make an axle like Ray's after all. I had a 53 belair with a stick and a babbit-pounder 235 when I was a kid. The 3.70 gears seemed about perfect, but then I remember the speed limit was 55 then.


That 4.11 and borg warner overdrive setup was common in a whole bunch of cars. I had a Nash with that. It really does make a tiny engine usable. Knowing what you know now, having driven your overdrive, would you have picked 4.11 to use with it if it wasn't already there? If not, would you go lower or higher?

I know you have the 4:88. I am sure your tranny gearing and tire size play into the equation. You can't push the brakes, front end, steering, etc. It is dangerous. Cruising at 55-60 mph at 2200 rpm's is a million times better than 55-60 mph at 4000. It makes you feel like you are going faster knowing you have more pedal and the anticipation of seeing your pistons all over the highway is gone! I don't know your car but we can all sympathize. Try to calculate what you need to reduce your rpm's to 2200-2500 at 60 mph. Factoring your hilly terrain you don't want to overwork the engine so 3:73 might work for you. Ray's set up would have been my second choice.
I have tripled the miles this year venturing further away with the OD. I looked at all my options and the convenience of already owning the OD and Mike's spare rear and torque tube made my decision for me.
As far as the 4:11 with it I know now that if I had a lower gear (3:55 - 3:73) with it the engine would have bogged at lower speeds. I only use the OD in third. It is not mountainous here on Long Island. For my situation it is perfect.

I missed that this morning. Was doing the research before breakfast.
Each Pontiac ring gear and pinion came with the correct case attached.
The Pontiac 4.11 gear and case is the only one from the bunch with a number series that Chevrolet used. I would be willing to bet the 4.11 came with the Chevrolet case and it has a similuar part number for the case of 602476 by coincandence.
For a simple change the 4.11 with the 6.50X16 tires would make the smooth straight eight very smooth up to at least 60 MPH.

My car guy uncle always called the Pontiac eight the "lazy eight" because of the lack of power for an 8 cylinder car. It was quite a small 8 with only 232 cubes.

Just checked my 1935 parts book The 601276 ring gear and pinion and case is listed for late 1935 Master. Does not appear in 1939 parts book.

HA! Well, this is a lazy six I guess. I have often wondered what they were thinking, as in a given year the Pontiac six and eight were always very close to the same size. The engine design is even very much the same. The cars are the same from the firewall back. They just added length to the nose to make room for the eight.

My tires are 600-16. That is 28 inches tall, at least in theory. I have good bias plies on the car, and a set of radials already here, also 28 inches tall. looking for wheels....

I did consider getting taller tires like 6.50 or 7.00, but I like the way it looks with the little 6.00s, and also radial choices are very limited in 16 inch.

The only older Pontiac 6 I ever drove was when I started in the dealership in 1950 It was a 6 Standard and was the slowest car on the used car lot. Looked like a low mileage original car at that tme.
Like I said, it was the only one I ever drove.
I had a 1935 Olds 6 and it had the strongest high gear of any car I had but had a 4.40 rear end and an over sped engine.

I know it is a different situation, but I once did the 3.55 (Power glide) gear conversion to an, otherwise stock, 1951 1/2 ton pickup. I moved the spring mounts on a '48 passenger rear end and modified the driveshaft length.
I did not convert the rear bakes because the truck owner decided not to do it.
The overall drivability of the truck changed dramatically. I would do it again without thinking twice.
My buddy, the owner of the truck, was not planning to haul hogs to market or lumber to a job site so a slight reduction in hill climbing performance was not an issue.
I was planning to use a PG gear set to build a rear axle for my '35 Standard but my situation has changed and I will not be making that modification. I have a '54 PG rear axle in reserve in case another need arises.

Mike

Bloo,

The center to center distance between spring perches on my '36 PU is 40 1/2 inches.

I'm slow in getting back to you on this because I'm in Santa Rosa CA where the fires you've been seeing in the news are. We were finally allowed to leave the evacuation center yesterday, a college campus, and come home to a house still standing. Others are not so lucky. Whole neighborhoods have been reduced to ashes as literally thousands of residences burned. The sky is still filled with smoke from fires still burning over a week after this all started.

Ray W

Sure glad your home is okay. It is a tragedy still happening. Don't know about several VCCA members in the Santa Rosa area. Sure hope their homes are okay too.

Some folks have used a S-10 rear end. Seems that the '36 rear hydraulic brakes are close enough to the S-10 fluid requirement that no modifications are necessary. Emergency brake is a different story but understand it is not too difficult to hook up.

Thoughts and prayers go out to all affected

Wow!

Glad your home is ok. Hope you and your family are all fine. Thank you for posting the measurement.

bloo, let me know if you need any photos of the project. I think they are all on this forum at this link:

https://vccachat.org/ubbthreads.php/topics/334876/1936_Chevy_3.55_rear_gear_conv

Ray W

Bloo,

I sold you that 3.82 gear set back in December. I agree with you that they should fit with the differential case in your Pontiac. In 1936, Pontiac offered three separate rear end ratios: Standard was 4.55 for the 8 cylinder and 4.44 for the 6 cylinder; Plains ratio was 4.11 ( 6 and 8 models); and Mountain ratio was 4.89 (both models. I had a 36 Pontiac Deluxe 8 Business Coupe, and it had a set of 4.11 gears in it that were from a 37-39 Chevrolet 1/2 ton truck.

I found the 4.11 gear ratio to be quite satisfactory, giving a good balance of torque and speed. With 6.50-16 tires, at 65 mph, the engine was turning at 3,250 RPM, which seemed to be reasonable for the 8 cylinder motor. In fact, with the engine rebuilt, I drove it at 3,500 rpm (70 mph), and I believe it could sustain that speed all day with no problem. With the 3.82, you could expect the engine to be turning about 3,000 rpm at 65 mph, but you'd also realize a 7% loss in rear wheel torque, which would manifest itself in requiring more throttle to hold the higher speed. Based on my experience with a 3.55 ratio in my 37 and 40 Chev pickups, I would prefer the 3.82 over the 3.55 for extended highway travel due to the limited hp/torque of the Pontiac motors.

I'd be interested in knowing if and when you get the 3.82 gear set installed in your Pontiac, and how you like it.

Incidentally, I embarked on a road trip from Reno to Maine back in June in my Pontiac, but I hit a deer in Wyoming, which mangled the left front fender and tore off the left headlight. Luckily, the car was still drivable and I drove the 865 miles back home without incident. Disheartened and not wanting to deal with the repairs, I sold the car, as is, in August.

Mark

Mark, sorry to hear about your car.

I hope to get the 3.82 put together this winter. Since I bought the gears from you I have parted out 2 36 Pontiac axles, bought all the bushings and bearings (all but one are not readily available), and had the best driveshaft out of the pile spray-welded and re-machined. I even found a riveter in Seattle willing to take on riveting the ring gear.

One of my parts axles had 4.11, and whoever riveted the ring gear on that one managed to bend the case. I could have it machined straight, but it would still be at the limit for in/out runout (eccentricity). It had also spun one bearing in the carrier, but just barely and had not done any real damage.

The other was a 4.44 that had rust damage and had spun both bearings on the differential case. The bearing mounting surfaces on that one are fairly shot. I suppose It could be spray-welded, or the bearings loctited on, but I am hoping for a better case.

I am picking up another axle soon. Hopefully the case will be good. The case really is the only holdup.

I would be ecstatic if this car would do 70mph indefinitely, but I was not really expecting it. I have the 4.89 now and am not comfortable taking it over 53mph. 45 is more like it for extended periods. I was hoping for a steady 60mph. My tires are 600-16, and the new radials I bought are dimensionally the same.

I am also looking for more wheels. I bought a set, but they are basically junk. If you know anyone wanting to sell some, send them my way.

Extrapolating from this chart: http://home.znet.com/c1937/RPM.htm 3500rpm with 3.82 ought to be about 75mph!

How did the torque of that Pontiac 8 compare with your trucks? Did it have aluminum pistons when you were running it at 3500rpm? Are the trucks 216s?

Ray,

Those pics seem to have been lost in the photobucket cash grab. They are probably still in your account where you can see them but nobody else.

I just found the PDF, so I have them now.

Bloo,

The 1936 Pontiac 8 was rated at 162 ft-lb torque and the 1940 Chevrolet truck 216 motor was rated at 168 ft-lb.

Both my 37 and 40 Chev pickups had their original 216 engines (rebuilt) when I installed the 3.55 gear sets in them, but I've since installed a 261 Chev 6 engine in the 1940 pickup. Now that is the perfect drive train combination. Plenty of reserve torque at 65 mph and probably capable of 85 mph or more, though I never drive over 70 mph (except when passing) because it just doesn't feel safe with the original suspension, steering and brakes.

When I rebuilt the Pontiac 8 motor, I installed .030 over aluminum pistons, and, with the 4.11 rear end, the engine was turning over at about 3250 rpm at 65 mph. I was quite confident that the motor could sustain that speed all day long, and, in fact, it did on many occasions until the deer collision.

The 1936 Pontiac 8 cylinder engine had a 3/8" shorter stroke than the 6 cylinder, and the crankshaft of the 8 was actually lighter than the 6, enabling a higher rpm red line than the six. The actual horsepower and torque differences between the two motors was pretty minimal.

Good luck with your project this winter.

Mark

I do not know the torque of his 6 Cyl. 208 C.I. engine but in my estimation a 4.11 would be about all it could handle on all but level ground. There was a reason they used a stock 4.4 ratio to give adquate performance.

Well, I guess we are going to find out. Their priorities certainly weren't the same as the priorities of modern drivers.

I have often wondered if it is a weaker engine than a Chevrolet 207 (the Pontiac is a flathead), or if the engineers just thought it could handle RPM better because of the full pressure lower end. They probably didn't want it to feel weaker than a Chevrolet in high gear, as it cost a little more.

It looks from the performance curves in the Pontiac manual, and in Buick manuals I have seen from the era, that the engineers were designing for what they thought was best use of the horsepower available, in other words maximum horsepower occurring at what might be the practical limit for speed.

It also seems that the measure of a good car in those days was how well it can pull hills in high gear without downshifting.

One thing the Pontiac manual does say is (paraphasing because I don't have the manual handy) "studies have shown most drivers drive about 30 or 35 miles per hour".

I do know that Buick Special gears are 4.44, and nearly every owner is clamoring for something higher these days. That is a more powerful car then my Pontiac, yet still 4.44.

Today, if you have a car that likes to go 35 or 40 MPH, it feels like you are going to get run over. I doubt that was an issue in the 1930s, or even something the engineers thought about. The wide smooth roads were still a few years away.

If this could do a relaxed 50mph, that would be much better. I'll find out this winter...

Bumping this old thread because I am back on the project again. The only thing I was missing was a decent differential case.

I got a whole 36 Chevy 1/2 ton rearend from a forum member here (Thanks, Darwin!) and took it apart yesterday. It is different inside than what I expected. The parts do not match the rear axles I have so far.

The first big obvious difference is that this one is full of bronze bushings. The differential pinions are bushed on the shaft, and they have bronze thrust washers behind them. The side gears have bronze thrust washers beside them as well.

The differential pinion shaft size is 0.746" and the shaft is stamped 1772555 (the other 36's are more like 0.800).

The differential pinions have 12 teeth, are bushed in bronze with a 0.747" ID, and are stamped 1760740 (other 36's here are 10 teeth with an unbushed 0.805" hole).

The differential side gears have 18 teeth and are 1.684" where they drop into the hole in the differential case. They have a 1.260 major diameter on the splines. No part number is visible.(other 36 gears here are 1.783" where they drop into the case and have a 1.250 major diameter on the splines).

The differential case is very hard to read for the part number, but is probably 1782860. The side bearings are New Departure 0103.(Other 36's here have a`case marked 369951 and use New Departure 0100 bearings).

Ring gear is marked 1769899 10-41, and is riveted on, as expected. Ring gear ID is about 5.63" (it is 5.42 of the Chev Master & Pontiac stuff I have here).

I couldn't find part numbers even close to these in the books on oldcarmanualproject. The axle is probably Canadian.

What on earth am I looking at?

1936 is way different than 1937. Improvements in engineering where coming fast. Since the 1920's and into the 1930's Chevrolet was moving forward every six (6) months with improvements (changing engineering) and going back and improving on their older models, too. So you could get an improved head and carburetor set for an older engine to improve horse power in a year or two after your purchase. This made Chevrolet a good investment as they were taking care of their customers. There are even differences in Early and Late 1936 Chevrolets. That is why 1937 will not fit 1936 and looks so different.

This axle came supposedly from a 1936 pickup. I saw the cab, and it looked like a 1936 low cab to me. None of these internal parts match the parts books. The parts should interchange all the way up to 1939 1/2 ton if one believes the manual.

This uses the same side bearings as a standard, but is a slightly larger diff than a master. The axle shafts are slightly bigger too.

It seems odd that they would tool up and build a whole different axle for a few trucks in Canada. I guess it must have come from somewhere else at GM. The only likely suspect is the 1936 40 series Buick, a one year oddball that is similar but slightly larger than Chevrolet Master. Those Buick axles were all 4.44. This is 41-10, so more like what you would expect in a Chevrolet.

I wonder if it could be GMC?

Does it have a torque tube?

Yes it has a torque tube. And 6 lug flanges on the axles. I have not measured the torque tube yet, but will today.

Oh, yeah, it has Huck brakes.

Torque tube (and punkin) length is 60 1/2" from the gasket surface to the end of the torque tube. The u-joint spline sticks on out to 62"

The diameter of the surface where the packing nut would tighten, at the front of the torque tube is 1 3/4".

Look At 1936 Master parts list.

1936 Master is what this should match but doesn't. Literally none of the major parts fit. Close, but no cigar. The part numbers are also way off.

I was hoping to identify this axle in case someone, somewhere could use it. It needs bearings, but the gears look to be in fine shape.

I will keep looking for yet another axle to get a 364538 (cast 369951) differential case out of. That is the only part I still need to start assembling my project.

I checked Buick part numbers from 1934-1940 and they do not match.
I would suspect it was a Canadian "Special".

That sounds right. Check Buick parts list or other GM brands.

Dosen't (numbers) show up on any other GM make.

It seems to be none of the above. This is a spiral bevel axle with hydraulic Huck brakes, the window is fairly narrow for when it could have been built.

Thank you Gene and terrill for the responses! I guess it is a real oddball.