VCCA Home Forums GENERAL DISCUSSION New User Forum 1928 Speedo drive

I have removed the speedo cable at the gearbox end. If I now remove the 1 inch fitting which surrounds the slotted speedo drive will the gear come out easily.
There is another slightly smaller fitting in line with the speedo drive but on the other side of the housing. Is this an oil filler plug for the speedo drive.
The speedo itself is not original but is working when I drive the cable with an electric drill. At 1500 rpm in an anti clock wise direction it reads about 30kph. However, no movement at all when cable connected to gearbox drive mechanism. I am assuming the drive gear is stripped but all advice gratefully received.
Regards,
Ray

Hi Ray,

I expect your assessment is correct. One test would be to connect the cable to the transmission and disconnect the end at the speedometer. Watch if the cable turns when the car is moving.

I’m not familiar with the design of the speedometer drive on a ”˜28 so cannot offer much help there. Hopefully someone more knowledgeable will respond.

Hi Ray,

Yes, if you take the 1 inch fitting that surrounds the slotted speedo drive cable, the drive gear and its shaft should twist and slide out.

The inline fitting on the other side of the speedo ball is not an oil filling place. It is a sleeve bearing that holds the other side of the drive gear's shaft.

The speedo gears in the ball housing are lubricated by splash method from the oil slinging around the u-joint. I usually keep around 1/2 inch of oil in the u-joint ball. I took a slim flat steel rod from an old window wiper and made a tiny dip stick that I put through the 1/8 inch pipe thread u-joint fill hole to check the oil level in the ball area.

The u-joint oil is the same as in the transmission and rear differential. I use Mobil 600W, which is what was originally specified and is still being sold by the Filling Station and others. Since I have two vehicles that need this oil, I purchased a 5 gallon bucket of it and it has lasted a number of years.

Cheers, Dean

Hi Rusty,
Thank you for your reply. I did think about disconnecting at the speedo and just taking it for a drive. I suppose it is possible that the tang on the gearbox end of the cable might be slipping but it feels firm just by hand. I should take the car out as you suggest but I am not feeling too hopeful at the moment.
Regards,
Ray

Hi Dean,
Thank you for your reply. If I do remove the 1 inch fitting, I assume only a small amount of oil will come out. Can I refill through there ?
I do not remember seeing a 1/8 " Pipe Thread fill hole for the U Joint. Is that on the top of the housing ?
Filling through such a small hole with relatively thick oil probably requires some patience but it sounds like it needs to be done to lubricate the U joint & speedo
I assume there is an O ring on the speedo drive shaft. Is that a standard size ?
Regards,
Ray

Hi again,

If you remove the one inch fitting, I suspect that all the oil that is in the u-joint housing will drain out.

The 1/8 inch pipe thread hole is to the side of the top of the housing. You can see it when you pull the floor board out. It might have an Alemite fitting or an 1/8 inch pipe plug. If it has a grease fitting, change it out so nobody is tempted to pump grease into there.

I put the 600W oil into a squirt can that has a flexible spout and squirt it in through the 1/8 inch pipe threaded hole.

It has been a while since I fooled around with the speedo gear and cable, but I don't think it has an O ring in there.

Here's a link to a short discussion on the topic: https://vccachat.org/ubbthreads.php/topics/459967/bentwood.html

Cheers, Dean

Hi Dean,
I removed the 1 inch fitting from the drivers side but the 'speedo drive shaft and gear' would not come out.
I removed the slightly smaller fitting in line with that and then the 'speedo drive shaft and gear' came out from that side without effort. (Passenger side)
No oil came out of either side.
The speedo drive gear was stripped, as expected.
I started to refill the housing through the filler at the top, as you said, and only put in about 20ml before it began to dribble from the passenger side.
I replaced the slightly smaller fitting and got another 30 ml in before it started to dribble from the drivers side. I replaced the 1 inch fitting (drivers Side)
I couldn't tell how much oil was already in the housing before I began to fill it but it seems I have only 50 ml more than when I started.
That's when I thought I would try your dipstick method. It took another 50 ml to give 1/2 inch on the stick but that was not from the bottom of the housing.
It is from the point where the dipstick hits an obstacle which might even be the side of the housing where the thread takes the slightly smaller fitting.
Sorry if this is a bit confusing but I think there is 100 ml above the lower level of the slightly smaller fitting on the passenger side.
Does that sound about right to you ?
Also, is it usual for the internal drive gear to be OK ?

Since you said that the dipstick was not reaching the bottom of the housing, I suspect your dipstick is hitting the u-joint. From your description, it sounds like you have way more oil in the u-joint than is necessary, but that's not really a problem.

The extra oil will leak out from the rear of the ball housing (onto the ground) and also will leak down the torque tube into the rear differential. I've read posts here on Chatter about people filling their transmission and then, after a while, draining the excess oil out of the differential. ;-)

I have not experienced a damaged internal drive gear, so I cannot offer advice about that.

What is concerning is that the metal pieces from the stripped speedo gear are still in there somewhere. ;-(

I suggest that you jack the car up (position the rear jack stands under the chassis, not the rear end) and open up the u-joint housing for an inspection and cleaning. By letting the rear end hang as low as it can, that causes the torque tube to pull away from the rear of the transmission and give you enough room to slide the ball housing back enough to take the u-joint apart. Support the torque tube with a floor jack while you disconnect the u-joint and then you can lower the tube so you can get to the rear of the tranny to inspect and clean out any metal chunks that might be around the internal speedo gear.

Also, look into the end of the torque tube for little chunks of steel. Maybe run a small magnet around the area and see what it picks up.

To find a replacement for the stripped speedo gear, start a thread in the Parts Wanted forum. Also, try Gary Wallace (http://www.earlychevyparts.com/). He seems to have a lot of good used parts.

While you've got the ball housing apart, you might as well get some new gaskets to help limit the oil leakage.

You'll find that putting the u-joint back together is a little challenging. I made a little lever tool (can you tell I like to tinker!) to hold the back of the u-joint forward while you put the nuts on to hold the whole thing together. Here are a couple of photos of the tool (the notches don't mean anything - they were on the piece of scrap metal I used}:




Cheers, Dean

I believe the excess will only leak into the differential if the torque tube seal is bad. If the 28 is similar to some later trannys then it should return to the main case so checking that level after filling (and letting settle) may be a good idea.

Hi Dean,
That's all useful information. Thank you for all your help.
Regards,
Ray Lilly

Hi Steve,
Thank you for your reply. I have recently filled the gearbox and I did expect it to run into the U joint given time. However, it certainly didn't rise above the speedo fitting in the U joint and I am not sure how much was in there already. I have been advised that if a particular modern seal has already been fitted it may not flow ether way. However, I prefer to think I have too much oil in the U Joint than too little and I have yet to check the oil in the diff. which reminds me I don't know the capacity of that either and I assume the recommended oil is the same as gearbox and U Joint (W600). Anyway, thanks again.
Regards,
Ray

Yes Ray same oil spec. The oil in the ujoint housing will splash around and lube the ujoint and gear.

I think you will find the speedo drive is above the fill plug. If you had time to do nothing you could fill the gearbox to the fill plug via the speedo drive but will take a lot longer as the oil will need to seep through the bearing.
Tony