I installed a fun projects modern pinion gear bearing set in my 26 rear end along with a new drive shaft, new U joint, axle bearing sleeves, seals, and new ring and pinion gear. All parts came from Langs. The first issue was that the drive shaft hole for the u joint is about half a hole width closer to the u joint bushing than the original drive shaft pin hole so the hole doesn't line up with the pin installation holes in the torque tube. I can work with this but the real problem is that the collar/pinch bolt assembly that is supposed to hold the drive shaft from sliding back into the differential doesn't hold. I've had this rear end apart at least 6 times in less than 500 miles because the collar slips, the gear lash changes and the rear end howls. I've worn the pinion and ring gear to the point that I can't shim any more to get the clearance and they will have to be replaced. My collar/pinch bolt assembly ID is smooth and doesn't have any set screws pushing into the drive shaft like I have seen in other threads on the forum. Is this a common problem and how do I overcome it? I thought about drilling and taping some holes for set screws in the retaining collar but am afraid they will slide and scar the shaft which would create a stress riser and cause a drive shaft failure. I have seen pictures of this type failure in my tribology book. I have a tour coming up in 4 weeks and would like to get this fixed before going. Advice please.
Chester Leighton in central Va.

Talk to John Regan. That bearing is his baby. I expect he can sort out what the problem is and what to do about it.

http://www.funprojects.com/

I sent him a message just now. Thanks.

You can't just drill a hole in the drive shaft for the collar because there would be no way to set the preload on the pinion bearings. Any upper drive shaft bushing has to be faced for final fit. And yes the pin need to be in place to maintain the proper geometry of the u-joint in the housing. Which kit are you using, there are two different styles. Do you have the spacer collar and shims in the right place, are you using too many shims if it's the adjustable kit? Are you using the locking collar to set your preload after putting the collar, bearing assembly and pinion on or before?
Compare your old drive shaft to the new one, if the the U-joint hole is in the same place then here has to be something amiss in the assembly of the pinion bearing.

See this post, go to the end to see John's comments about the collar.

http://www.mtfca.com/discus/messages/506218/552538.html?1435983114

Chris;
Thank you posting that link, I looked but could not find it.

RE; "new U joint" pay attention of the information in the last entry by John about the new u-joints.

Ignore any bits posted by others re; not using the pin to hold the U-joint, IT IS NEEDED.

The u joint hole is further from the end of the shaft(tranny end)on the new shaft than the hole on the original shaft. I'm using only the thickest shim between the gear and the Timken tapered bearing. The collar is then slid down the shaft to set preload on the whole assembly and then I tighten the pinch bolt, as the instructions direct. I tightened it so much the third time I broke my allen wrench and it still moved after driving 60 miles or so.

Read what John posted about drive shafts. It is not how far from the transmission end that applies, it's the measurement from the other(pinion) end. Check the length as posted in below. it could also be the case at this point that the collar needs to be replaced, it may now be scored or out of round and is no longer making full contact with the drive shaft. Also check the fit of the u-joint on the shaft to see if it is fully seated and the holes lines up and that it's not binding when being inserted into the tail shaft.

Top of pagePrevious messageNext messageBottom of page Link to this message By John F. Regan on Saturday, July 04, 2015 - 12:11 am:

Chester:

Something in your statement about the shaft collar moving makes no sense to me. First off the shaft collar we use has a side thrust load testing at 2600 lbs assuming the drive shaft is 1.000" and smooth. We clamp test them on precision shaft and push them with a press to make sure. That being said that shaft collar only carries the vector weight (it is installed at an angle) of the shaft itself and parts fastened to it or simply something less than the weight of the drive shaft mounted parts. Thus NOTHING should be pushing that collar up the shaft. Since the T rear end is a straight bevel gear then the thrust under engine power or under transmission braking is always in the same direction namely that the ring gear is trying to spit the pinion gear up the drive shaft housing. You stated that the collar was slipping under braking and that the drive shaft was being pulled downward at that time - how? If the collar was not set up as per the instructions and there was end play between it and the bearing then you could have movement and I suppose if you had enough movement you could make the drive shaft into a battering ram but it would not be easy to move that collar since we have put more than its rated load against it in tests and it didn't move. Now if your shaft is worn badly at the location where the collar sits and/or not a true 1.000 diameter then that collar will not grip the shaft. If you drill holes in the collar and add set screws then you will in fact lessen the holding power since the collar depends on surface area and pressure and you will be using the set screw to pry the inner surface away from the shaft and replacing it with a small round spot. Check the side thrust rating on regular set screw collars and you will see they are less than single split collars. I simply don't know how or why the collar is moving but suggest you need to look carefully at what is pushing on it. The only thing I have heard and that did push a collar away was one of the new ujoints which did not fit into the back of the motor since the square shank was oversize and jammed which pushed the entire drive shaft backwards as the fellow drew the ball into the transmission rear end by using longer bolts. Likely a disaster for all parts involved.

Perhaps I don't understand what you were saying was happening but did wonder if perhaps you were having that same issue of ujoint not fitting smoothly and easily into motor.

The picture of the 2 drive shaft ends is not meaningful since the shaft length isn't critical but the placement of the ujoint pin IS critical. The location of that pin is measured from the edge formed by the pinion taper and the 1.000 diameter shaft machined land. Thus the correct length of the pin hole distance is a long dimension of 51.250 +/- .005 in length thus rather critical. Think about it - the length to the pin hole MUST be held to a dimension that starts at the pinion gear end. The problem is that the maker for awhile would seem to have measured the short end distance from some T shaft rather than buying the drawing and you could very easily get the wrong distance by taking any dimensions between 2 shafts using the short end where the ujoint hole is.

The ujoint must not float - pin it but at the correct location.

So John is saying ,in the referenced thread, that it is possible that the Ujoint is sticking in too far and the shaft gets shoved into the differential when the drive shaft is bolted into the engine. This may be what's going on. I'm using a new drive shaft and Ujoint from Langs and the ujoint pin hole in the new shaft doesn't line up with the hole in the torque tube. The hole in the new shaft is closer to the b upper thrust bushing than the hole in the original drive shfat so I wouldn't think it would be making the entire assembly longer but as John says, I need to measure from the end of the taper at the pinion end to the hole to see what is going on. I haven't experienced any trouble getting the drive shaft installed in the transmission and am using the stock bolts at the ball joint to put it together. The first 50 miles or so are O.K. then the growling begins when braking. When I take the rear end apart, the pre load on the Timken taper bearing is gone, very loose fit and I can see where the collar has slid slightly on the shaft. I haven't checked the new drive shaft OD yet, I can do that next week end when I take it apart. If the issue is the Ujoint sticking into the transmission too far, can I trim some material off the end of the square shaft on the ujoint (say 0.150")and solve the problem?

Clean the male end of the U-joint good, take a magic marker and coat that end with it's ink. Let dry then slide into the tail shaft. Look for any high spots that are scraping or binding as it slides in, dress those down and try again. He is talking about over sized on the square not the length.

Did you make sure to check the lower inside diameter of the tube as stated in the instructions? If the tube is pushing the collar down it may be forcing it into the pumpkin. That and how many gaskets if any are being put between the drive shaft tube/bearing carrier/pumpkin? if you are using the shims you should not need any, just sealer.

The issue is that the u-joint IS NOT going into the tail shaft far enough, not going in too far.

For the record, the ujoint slides easily into the transmission square hole. Initially I did a fit test of the ujoint by itself to see how it fit in the transmission shaft and I did have to file it a little to gate a smooth sliding fit. This was done before it was ever mounted on the new drive shaft. After it's installed, there is a little play in the ball/socket fit and when I set the parking brake, the torque tube moves forward into the ball socket, by how much I don't know but I can see it move. This lead me to believe that ujoint binding isn't the issue. In order to make the bearing collar move, the shaft must be forced in the direction of the differential while the collar stays still. The shaft slides through the rear ball bearing and the collar cant go with the shaft so it in effect slides up the shaft. If the ujoint is bottoming out in the transmission shaft either when the torque tube is bolted up or for some other reason at some other time then the shaft will be pushed into the differential as John describes. At this point, I need to verify the ujoint pin hole location dimension, the new shaft diameter and inspect the bearing collar or replace it as previously mentioned. If I don't find anything out of spec with those checks then I'm not sure where to go from there.

Chester;
At this point that's all I've got to give. It's one thing to have something IN HAND and another to diagnose picturing it in my (our) head. I installed one of his kits, the non adjustable one, no issues so far with it. Every thing lined up using new drive shaft from Snyder's, Lang's may be made by the same people.

(Message edited by redmodelt on August 04, 2015)

Chester, I always tack weld the collar to the shaft when all is set up then you can leave the set screw out or use high strength thread locker to hold it. I just take it out when the tack welds are done, never a problem in thousands of miles. I do not re pin the u joint either and have had no problem. KGB

The reproduction drive shafts are not made properly. This is not John Regan's fault. He does not make drive shafts. Find a good original drive shaft. Problem solved.

I have no skeletons in my closet and have made not a single change to the bearing kit that we have supplied for years now. If the collar slid then something pushed the drive shaft down and perhaps by now the bearings in the pinion spool are damaged since the lower roller bearing is not something that can bang around and then simply be put back into service. In another thread where a 2 piece drive shaft housing was used it has been discovered "off line" by numerous emails between myself and Bob P. that the driveshaft ujoint hole is drilled in wrong location but also the 2 piece drive shaft housing is fake "made up" unit that has parts brazed to a later one piece drive shaft housing that had the ball cut off. The pinion bearing kit arrived here today since it was damaged. The drive shaft housing was not "faked" to correct dimensions and is also longer than original with all this resulting in a the ujoint hole being a full 1/8" in the wrong direction with about half of that error being in the driveshaft. The questions posted on this thread have not been answered in that there simply is no normal force that can move the shaft collar. If the hole is way off then was the ujoint ever pinned? I don't see how. If you found that the ujoint part that entered the motor needed file work to make it fit then you should have ditched it right then because now it is hardly a precision part any more and why are you so sure that it won't then jamb at some point when there is engine driving force or braking force trying to turn it while it then must also slide in and out smoothly. Get an original ujoint that is even a bit worn and use it with a correctly made drive shaft and let me replace the bearings in your drive shaft spool to make sure that you are starting out again with everything made correctly. You cannot simply "forge ahead" and reuse a likely damaged bearing which has been run without proper bearing and pinion gear position and preload. Measure the shaft diameter at the machined end. If it is undersize then the shaft collar won't hold. It should measure exactly 1.000 Welding the shaft collar in place will ruin the drive shaft and collar and you have not fixed a thing since the force that pushed it will still be there but will then push the guts out of the pinion bearing housing itself. There simply is not a "normal" force in the downward direction that exceeds even 30-40 lbs (weight of drive shaft, ujoint, and pinion gear) so what on earth doesn't fit right - most likely the ujoint. You need to start over with correctly made parts or you are going to simply repeat this over and over. Another new pinion bearing kit isn't going to fix anything if you keep the same ujoint and drive shaft methinks. They are both made by the same company I think. Does the motor have any sort of modern 4th main bearing setup that might not be made to correct dimension and prevents the ujoint from being able to go completely forward when the rear wheels run up over something that results in the rear end going "up" which attempts then to force the ujoint forward? I am just guessing here but something is hitting something that is driving the drive shaft downward like a battering ram - simply find out what that is and you have solved it but you then need also to replace any damaged parts caused by it. I sent you an email tonight when I got your email but I didn't know who that email was from until I read this thread so I assume it was from you. Call me tomorrow and lets see if we can't figure it out.

John, thank you for clearing up the fake two piece torque tube issue raised earlier on in a thread about the u joint pin which was out of line. I suspected as much when I asked for a photo of the whole casting at the front end. My suspicions were further raised when a two piece torque tube was advertised for in the classifieds.

Allan from down under.

My buddy's car had the problem of the driveshaft being driven back also. To the point where the force overcame the locking collar in the FP bearing.

Problem was, he put and extra gasket behind the fourth main cap, where none belongs, and also used way too much sealant, which he allowed to set up before installation. Result was tons of end play in the torque tube ball & socket. When he came to a stop, the ball pulled back. When he accelerated, the torque tube got thrust forward, BUT the u-joint, which was under the driving load of the engine, did not want to slide within the output shaft square hole. Instead, the driveshaft was thrust backwards, overpowering the Fun Projects locking collar and driving the pinion gear way too far back into the diff housing. Luckily, it was caught before any real harm was done. With everything reassembled as it should be, it works great.

Got anything like that going on?

Taking into account the story I related above, be aware that even with everything assembled correctly, extreme wear in the torque tube ball socket, that allows for excessive fore & aft movement, may also contribute to or cause this problem.

I got things pulled apart today and made the measurements John Regan recommended. I took measurements of the u joint pin hole on each drive shaft by installing the pinion gear with the nut hand tight and putting the tape measure at the back of the gear then measuring to the centerline of the u joint pin hole. On the stock Ford drive shaft I got 51.250 or 51 and 1/4 ". On the drive shaft that I pulled out of the car which I had purchased from Langs I got 51 and 3/16". I checked my stock Ford shaft diameter in the area that the collar will clamp to and I got 0.9995" on my digital micrometer. The Langs drive shaft measured 0.9983". I checked the sliding fit of the U joints into the transmission shaft and both Langs and my stock ford U joint slid in easily and moved easily while I had a twisting force on them. I took some measurements of the U joints from the center of the pivot pin to the center of the retaining pin hole. This was tough because the centerlines of the se holes are not in the same plane. I took the measurements by measuring from the bottom up to the pivot pin and the from the bottom to the retaining pin and subtracted the retaining pin distance from the pivot pin distance. The stock Ford distance from retaining pin to pivot pin was 1.8". The Langs U joint measured 1.9". I'm not sure what the net affect of the Langs U joint and drive shaft had on the critical dimension of matching up the u joint pivot to the torque tube pivot point on the center of the ball but with all the trouble I've had, it couldn't be good. I'm sending my bearing assembly back to John at his request for an inspection and replace what ever parts he thinks need replacing then I'll reassemble with a stock Ford drive shaft and U joint and see if I can get the ring and pinion clearance set again.

Here is the stock drive shaft

Here is Langs drive shaft

Here are a couple shots of the U joints. Notice that the stock Ford (the one with the numbers on it) is a little beefier than the Langs U joint

Maybe you'll need to check the critical dimensions of the torque tube too, if it's a homemade unit made from newer one piece tubes to look like an older two piece tube?

Roger:

This car is a 26 and I don't think there were be any reason to make up a fake torque tube as was being done on the 1912 that Bob P. was doing since the '26 doesn't use a 2 piece drive shaft housing.

Oops, mixed up this problem thread with other similar problem threads where a questionable two piece tube was involved..
http://www.mtfca.com/discus/messages/506218/549584.html?1434493132
http://www.mtfca.com/discus/messages/506218/552538.html?1435983114