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I figured you would enjoy this story. I have a 1967 CS Holiday Coupe that I am in the middle of attempting to make a daily driver. My latest issue has been no speedometer. I found out that the speedometer drive gear was toast, so I ordered a new one. Then I found out that the worm gear was no longer being held in place properly. This is when I decided to take it to a transmission shop because I have no lift. The transmission shop is now telling me that the reason the worm and drive gear were buggered up is that my drive shaft was too long! SO now I am waiting for the drive shaft to be shortened. However, I can't help but wonder..... How does a 50 year old car shrink or a drive shaft grow? It has been hit in the trunk but I see no evidence of frame damage/warping.
Either someone swapped out a different drive shaft or when it was hit in the rear, the force "center punched" the drive shaft momentarily forward doing the damage. Just a thought.
Good theory. Although the transmission shop is telling me that the drive shaft needs to be shortened. So, what do I look for as far as problems once I start driving with the shortened shaft? I want to be able to blame the transmission shop if I start seeing drive line issues once they have shortened the shaft.
There should be about 3/4 inch gap between the transmission seal and the part of the yoke where the ujoint is installed. Are the rear end or control arm bushings worn out allowing it to move forward?
It is the original Jetaway trans. However, I have only owned this car for about 6 months and I don't know everything that was done when it was restored about 5 years ago.
There's another option - the trans shop is full of manure.
Note that the speedo drive gear is well forward of the forward end of the splines. Someone please tell me how the yoke can move that far forward - unless the driveshaft has some non-original yoke with a looooong section forward of the splines. I've never seen that.
This is easy enough to test. Temporarily remove the tailhousing. Slide the yoke onto the output shaft and see if it is even possible to contact the speedo drive gear. Methinks you have unnecessarily (and incorrectly) shortened the driveshaft.
There's another option - the trans shop is full of manure...
And a very valid option. The other transmission options would require a shorter shaft and there is no longer shaft requirement or available stock for the car.
there is no longer shaft requirement or available stock for the car.
The only possible way the driveshaft could be "too long" is if the car originally had a Type O axle and the axle had been replaced with a Chevy axle. The Chevy axles have the pinion flange about 1" further forward from the axle centerline than does the Type O and thus the driveshaft would need to be about an inch shorter. That still doesn't explain how the yoke moved forward of the splines on the output shaft.
I would think that the drivetrain would have some obvious strange noises if the drive shaft was long enough to cause damage and the speedo gears would obviously not be the only issue.
I would think that the drivetrain would have some obvious strange noises if the drive shaft was long enough to cause damage and the speedo gears would obviously not be the only issue.
Here is a theory someone broke the drive shaft (u-joint etc.) and had to replace it to drive the car and they got a junk yard one and put it in there. REMEMBER - not everyone is going to take the car to the shop or just repair what needs to be done. ...QUOTE ' Oh well a buddy got me it for FREE!!!!! ' end quote lol.
OR the transmission is not original to the car... or the rear is not original to the car...GOD it could be anything....
Vehicles this old especially MUSCLE CAR ERA cars are notorious for all kinds of junk getting thrown in.
YOU should see some stuff we get in that people have put together or shops have installed in rears. Parts that do not even belong in rears...lol 8.2 parts in 8.5 rear wrong series carriers and gear sets??? It is insane...
You better set aside some more money cause it is going to keep on rolling...lol.
I got the car back on Friday, they were able to fix the gears that drive he speedometer. However, they were also able to prove that with the suspension in full travel, the end of the drive shaft did indeed impact the worm gear. I now have a shortened drive shaft, new U Joints, and a new set of gears, and a speedometer that works. The folks that shortened the drive shaft said that it was a GM shaft from the correct period but that they expect it was from a larger car than a Cutlass.
Last edited by babailey; April 1st, 2018 at 06:41 AM.
March 29th, 2018, 06:21 AM
