VCCA Home Forums TECHNICAL - 1945 AND EARLIER Chevrolet Speedsters Differential options

Hi all, I know things are pretty shitty in the US at the moment, so the last thing on your minds are cars, so my question may go unanswered, but I was about to rebuild a 28 diff n torque tube for my speedster, but thought I'd ask what others have run in theirs, I do have a new set of axels and tail shaft from Billy Possum as the tail shaft was the Achilles heal of Chev fours and prone to sheering off the pinion tip, but maybe there are other considerations when hotting up the motor to more than double its factory horsepower, that may stress out other parts , Ray

A few years ago I went to look at a Chevy speedster. It had a '28 engine with a downdraft carb and a '38 transmission. I think the rear end was newer with hydraulic brakes. It had '30 wire wheels. The nice part of the later transmission is the 2nd & 3rd gear synchronizers. With your Billy Possum axles and driveshaft you shouldn't have any problems. If someone wanted heavier axles on a budget they could use 30/31 or if you can find them early 32 axles. They were beefier than the original 25 to 29 axles. Many of the people building speedsters rework the weight of the flywheel/pressure plate. Even to the point of machining the flywheel flat and using a more modern pressure plate. Look at the NW Speedsters web site. There are some Chevy speedsters in there. You might be able to email some of those people to see what they did.

Ill have a look for sure, I have a pair of SU's on mine, Looking at a later model Holden ( GM AUST) flywheel as they use the same size clutch plate, which I have been running in my 28 ute fro 25 years, The late axels don't fit pre 29 they look the same but the spline is 0.0500" bigger , what bastard sat down and though of that !. I did have a 29 Dodge fast 6 rear end I thought about using, much beefier and hydraulic brakes but figured too much hassle to get through our registration here, Ive also got a modification for the water pump so I don't blow out the front bush , had that happen once on my ute when a fan blade snapped off , wasn't pretty. Im running 19" wire wheels and 12 volts , Ray
First run on old chassis https://www.instagram.com/p/BZMjSnPBSfe/

Last Sunday finished the front end.https://www.instagram.com/p/CB4VJK9D9tm/

Sunday 20th June 2020 https://www.instagram.com/p/CB4VJK9D9tm/

My sprint car pictured above was constructed out of an Overland chassis including the front and rear end. I restored the Overland rear end. The axles are twice the size of original Chevrolet. The axle bearings are huge and still available today. The original Overland drive shaft was cut off and the Chevrolet ball cap was installed and connected to the '1928 Chevrolet transmission.. This was done in the 30's and it seems to have been an easy solution to the sissy Chevrolet rear axle problems.

brasscarguy

Some time back a fellow from one of the regions near Seattle put together an axle chart for interchange. I think it was one of the Folsoms. The early 32 axles were slated as replacements for most of the previous models. The stipulation is that you have to use the spider gears of the axle you choose to use. I have access to a 30 rear end and am going to check out the axles for my 28 project. They are bigger than the previous axles, should be heavy enough for a 4 cylinder, and free is a good price. Art

Art,

Are you able to dig up that axle chart? I am trying to swap the rear end in my speedster project and that information would be incredibly helpful.

Thanks

Art, you can use the later 29-31 axels but you have to change the sun gears in the diff centre as the spline is 50 thou bigger. I have heard assorts of options over the last 30 years of using Jeep axels, early Holden and even Fiat but none of these are true . If you want to stick to your Chev diff and torque tube you have two options buy new repro axels, which for my mind is the best financial option as you will never have a future problems, like pieces getting in and chewi
G up your crown wheel. Or find old Dufor replacement axels they are easy to pick as they are machined the full length of the shaft not cast like original axels. Ray

So surgery and world pandemonium aside I'm pressing on with my 28 special, the diff I have put aside for now and onto the motor, I have decided to go with special pistons, higher side but dished to increase the compression and give a better combustion chamber shape, and to engineer an oil feed to the bottom end for better oiling, I already have a twin SU carby set up that I used on a shakedown run on my 28 ute motor, also on the shakedown run of the carby the extra fuel flow and acceleration snapped a flywheel bolt so need to beef that up too. the weak point I think to next address is the water pump and its front bush, with the increase in Revs and torque i think I need a better solution, Any suggestions? Ray

Modify the housing to take a modern water pump bearing & seal like I've done to my '28 truck & '29 Olds.

Have you got a pic CJP?

Only thing I can do is take a photo of the one I did for my truck,but as I'm not a member,I can't post it.

CJP, if your photo resides anywhere online and it can be reached via a web address, you can include a link to it in your post here in the VCCA forums.

Just use the Full Editor and click on the Insert Image icon () and paste the web address of the photo into the pop up window. You'll end up with code like this in your post:


And, here's the pic in the above code example:

Cheers, Dean

You can email it to me and I’ll post it. info@raycycled.com

Dean,
Your picture is a TT Ford cab grafted onto a Chevy truck chassis/cowl. Oh the ingenuity.

Mike