TR4/4A TR4 rear axle piece fell of into my hand?

[SCguy]

I was topping up the oil in my rear axle ans I notice a slightly loose piece. I jiggled it and it fell off into my hand. It appears to be some sort of locating or holding pin for my rear axle. Looks like its none stock. Hopefully the pictures will tell more to someone familiar with the TR4 staight axle.

The hole on the rear axle from where the piece fell out.

The piece that fell out.

The otherside of the axle with what looks to be a correct pin

Clearly, I need to repair or replace. Any idea how? How safe would the axle be to drive on? All the other pins look stock and secure.

 

[Bugeye58]

It looks like the vent. It's been a long time since my TR4 days though. Is it hollow?
Jeff

 

[TR6oldtimer]

Yep, looks like the vent. Lucky you still have it, as a part, they are no longer available.

 

[SCguy]

It's not the vent and the picture is not from the top of the axel.

I'm pretty sure that it's one of possible four pins from each side as shown in my last picture. The faxtory pin is missing and the piece from picture 2 and 3 show what the prievius owner or rebuilder stuck in the hole. None of the manuals show a replacement pin or part.

 

[Andrew Mace]

I'm guessing it is some sort of pin that actually helps hold the axle tube to the "differential case"? How critical it is in terms of driving without one of them I don't know....

 

[SCguy]

That's what I think it is as well, but to repair or replace?

 

[tdskip]

No dice with the Moss or VickyBrit catalogues?

It does like like it needs to provide location to the tube, but that is only a guess on my part Larry.

 

[Andrew Mace]

That's what I think it is as well, but to repair or replace?

Don't know. As you noted, they're not listed even in the original factory Spare Parts Catalogue. Although the drawing of the rear axle housing kinda shows where they go, the pins (or whatever) are not shown separately, nor do they appear in the list of component parts.

Got any good axle shops in your area that you could call and ask about this?

 

[TR3driver]

IMO, time to look for a replacement axle housing. As noted, those pins lock the tubes to the differential housing casting. They take some of the force when cornering, and any movement will upset the bearing clearances.

Repair isn't out of the question, but IMO the condition of that pin shows that the tube has already been moving in the casting, which means there will already be some wear and damage in the joint (which is supposed to be a snug fit).

TR3 housings seem to be plentiful and cheap; so I would guess TR4 housings are similar. Ask around at your local club, I'll bet someone has one laying around that they would let go cheap.

Hmmm, well, maybe the local club isn't such a good suggestion. That would be Triumph Travelers, right ? Kind of a long drive from Colfax to Sunnyvale.

 

[Merlin63Tr4]

That loose part is one of the axle tube locating pins. What worries me is what made that pin shear off ! The axle tubes are a light press fit into the differential housing and then the pins were driven in and staked in place to hold the tubes in place and take shear loads. Looks like there has been some excessive load placed on that axle tube which has caused the axle tube to bend, thus moving it in relationship to the differential casing and then shearing the pin, not a good thing. Look carefully at your rear axle assembly and you might actually be able to see a slight bend in it. I would personally look for a replacement unit and not fool around with a repair, but a repair is possible if the tube or differential housing are not too badly damaged.

If the other pin in that tube is still in place and tight you might have a chance of saving that rear axle. A machine shop should be able to realign the axle tube to the axle housing,re-drill the locating hole and machine a replacement pin to fit the hole. Then the newly installed pin should be staked or welded in place.

Good luck.

 

[SCguy]

Here's the thing. This pin is a replacement pin. It's clearly not orginal. I get the feeling that it was just driven into the hole. The rear end was just rebuilt along with the engine and transmission. Didn't even have gear oil in it.

I just went out and counted. There should be 5 pins per side. I have this makeshift pin and the rear is totally missing one other pin (only three pins are correct. This would have been nice to have noticed before bolting the body on and restored the rest of the car.

The pains of buying a partially restored car...

 

[Merlin63Tr4]

Larry, I just went outside and verified the number of pins on my '63 Tr4 rear end and there are only two per side on the inboard side of the axle tubes. Looking inboard from the wheel side one pin is at the 1 o'clock location and the other at the 7 o'clock position. You have five pins per side! /bcforum/images/%%GRAEMLIN_URL%%/shocked.gif

 

[Merlin63Tr4]

Forgot to add that there is one larger diameter hole, per side, thru the differential housing to the axle tube. These holes are located on the aft side. These holes are supposed to be empty. They are parallel to the road /bcforum/images/%%GRAEMLIN_URL%%/blush.gif

 

[SCguy]

I went back out and counted again. There are (or should be) four pins. Two inner or closest to the axle. One one each side of the axle. These pins are fine.
Then two outer. Again one on each side of the axle. These are the ones which are missing or the one that the weird pin pictured came from. The large diameter hole is there, empty as described.

If I could buy these pins I bet I could just drive them in.

 

[Merlin63Tr4]

Ok Larry lets see if we have this correct. Your rear axle assembly (like mine) has qty(4) staked pins holding the axle tubes per side. One of the pins located toward the outboard side of the differential housing (side closest to the wheel) has sheared off. Is this correct? Can you take a good look down the hole were the pin came from and see if the axle tube has shifted in relation to the differential housing? Also verify that the pin located directly opposite the failed one is still intact and tight in its hole.

 

[SCguy]

One side has the two inner pins (opposite of each other) still intact. The outer pins are missing. Nothing seems to have shifted when I look into the holes. The axle is rebuilt. I did drive on it for about 30 miles, but all seems fine. I think I need to try and get new pins put in the axle, but how? Drop the axle and take it to a shop of some sort?

 

[TR6oldtimer]

If I may suggest, take a lot of pictures then find a shop that is willing to take on the project. A good machine shop will have a lathe and boring tools as well as access to the steel stock needed to fabricate the pins. Once found, they will tell you whether to remove it or just bring in the car.

 

[TR3driver]

If you go that route, be sure they can get the bearing flanges parallel. Otherwise your rear wheels won't be. And don't forget those joints carry part of the weight of the car, not to mention extra stress when you hit a bump.

Had a somewhat similar problem years ago on a Dodge Dart. Since I'd only paid $25 for it, I wasn't going to worry about the rear axle, gave it to my sister to drive til it dropped and junk it (again). But, Dad was worried it was unsafe, so he took it to a shop to be repaired. The shop welded up the joint without even trying to get the tubes in line, then the weld promptly broke. Car still drove fine, but the safety inspector took one look at that broken weld and flunked the car.

I tried to convince Dad to smear the crack full of grease and take it to a different inspector, but he wouldn't do it /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

 

[Merlin63Tr4]

Larry, if you go the repair route listen to Randall's (TR3driver) advise about making sure that the bearing flanges are parallel to each other after the repair! Have you checked for small hair line gaps between the axle tube and the differential housing right where the pins are missing?

If you noticed the pin that fell out is a stepped pin and a piece of it is still in the axle tube. That piece must be removed in order to drive a new replacement pin. I'm afraid that to do a proper repair the rear end will have to come out. Its not that big of a job.

I think, you will find that the cost of having a machine shop perform the repair will be more that the cost of buying a good replacement unit. /bcforum/images/%%GRAEMLIN_URL%%/frown.gif

 

[SCguy]

Here's what a local mechanic and TRF suggested. Take the axle out and get it welded. Apparently that what a lot of racers do. The axle is out. It all looks freshly rebuilt as promised. The half sleeve doesn't appear to have moved and I've found one who say that he can do the weld. I'll take it to him tomorrow.