MTFCA Forum

Does anyone have cure for the u-joint being loose on the driveshaft, it moves enough to brake the pin that holds the joint to the driveshaft. I am hoping not to have to replace them. Thanks.

Check the driveshaft and of course the inside dimensions of the u joint. They should not be breaking the retainer pin.

All the Best,

Hank in Tin-A-See

Take out the broken pin and let the u-joint float. It will find its running position and no pin to break and come loose . Pinion thrust is always forward. No force is available to push the pinion into the ring gear.

DO NOT LEAVE OUT THE PIN. If the pin is being broke, you need to find out why. The pin does two things, keeps the pinion gear from moving back into the housing at the rear and centers the U -joint in the housing in the front.
How is it loose? Stock pinion bearing or modern? Sounds like a lot of play in the parts if the driveshaft can move enough to the break the pin, time to open things up and look.

As I stated in the original post, the looseness is between the joint and shaft, does anyone know of a good way to take up the clearance without replacing the joint and shaft? Thanks, Dennis

Perhaps the pin is too small?

Then try a different u-joint. I would suggest shimming but would be a real pain trying to fit shim stock without being able to see what thickness would be needed.

The joint and shaft are a slip fit. They should easily slip together and apart. If the fit appears sloppy, then maybe one of the parts (or both) require replacement. You do need the pin to hold pinion depth and to center the center line of the u joint inside the center of the ball. Without the pin, gravity allows the pinion to drop to zero backlash and most ring gears have a couple thousandths varience in backlash, so without the pin installed there will be some “hammering and binding” going on at the ring and pinion, unless you have a modern pinion installed... In which case you still have to keep the u joint centered in its ball.

To put it simply, there is excessive wear in the joint or drive shaft. The joint should be a snug slip fit. If the fit is correct and the holes in the drive shaft and joint lineup there should very little or no noticeable movement when looking down through the holes when trying to move it back and forth.

Adam wrote: ↑

Wed Mar 06, 2019 11:18 am

unless you have a modern pinion installed... In which case you still have to keep the u joint centered in its ball.

That is the best reason I've heard so far...for continuing to use the pin when using a modern pinion.

You may be able to slot the hole in the u-joint slightly so the pin doesn't take any torque. Just a band-aid, but probably would work ok untill you can take the time to replace things to spec. This happened because there is not enough lubrication in that area. Do you have a modern 4th main? These will starve the u-joint. I know that it is supposed to be lubricated from the grease cups but all things known, the engine oil does flow down the touque tube and into the rear end. Sometimes you even have to drain some oil out of the rear end. So I guess what I am trying to say is that the model T by design will sorta try to take care of itself.

tdumas wrote: ↑

Wed Mar 06, 2019 9:58 am

Take out the broken pin and let the u-joint float. It will find its running position and no pin to break and come loose . Pinion thrust is always forward. No force is available to push the pinion into the ring gear.

Ted, this is wrong in so many ways. Please don't do that.

Dennis Prince wrote: ↑

Wed Mar 06, 2019 10:46 am

As I stated in the original post, the looseness is between the joint and shaft, does anyone know of a good way to take up the clearance without replacing the joint and shaft? Thanks, Dennis

Dennis,

Take it apart, find out what's worn, and replace it. Anything else will be a band-aid and will be a temporary fix that you'll have to do over the right way anyway.

From the responses that I got I am guessing that no one has a good trick repair so I ordered a new u-joint and I have another driveshaft, I will see how the joint fits when it gets here. Thanks, Dennis