TR2/3/3A Rear End Problem

Well, the only thing I didn't rebuild on my TR3A was the rear end. Was 70 miles from home last weekend, headed up to Ironstone Winery in Murphys, CA to a beautiful Coucours d'Elegance.... And it sounded like a leprechaun snuck into my rear end and started pounding his way out with a sledge.

Towed home, put her away, and was hoping for a U-joint failure. Guess it's not my lucky day



So, clearly the ring gear is toast. Can I obtain new guts (or used) and put this thing back together? Or better to just replace it outright with another used rear end? I'd rather obtain a donor rear end and have a differential repair rebuild mine. That would give me a fully rebuild diff and I wouldn't need to worry about it for a while. Also, I'd like to keep this rear end case because I spent the better part of a weekend cleaning and painting this one and I would hate to have to do that again.

Thoughts? Recommendations? I assume the pinion is also trashed so there may not be much to salvage here.

Thanks

Pat

Pat, Sorry, not a good day. Used units are pretty easy to find and easy to install. The condition is somewhat of a gamble but if you can examine it with the cover off, you can get a fair idea. I had a similar experience with a broken tooth on the ring and I bought a used unit with brakes and all. Had it up and running in a short afternoon. Changing the ring and pinion (they come as a unit) is a bit more difficult as they need to be disassembled and properly set up.
Tom

The ring gear and pinion are a matched set, and should be replaced together even if the pinion looks perfect. Obviously you'll want to replace all the bearings and thrust washers, and may very well find more damage on the other gears.

With that much damage, and my experiences both with rebuilding an LBC diff myself and with having a non-LBC rear end rebuilt by so-called professionals; my suggestion would be to look for a good used one from another car.

First of all, you can't "just put it back together". Clearances and preloads have to be checked, shims replaced and changed multiple times, and several unobtanium tools are involved. Read through the manual section, and check out the slides at
https://s258.photobucket.com/user/TR3driver/library/Stag diff to see part of the process. (Obviously that's an IRS diff, but the differential portion of a TR3 axle is exactly the same. I've got a TR3 axle apart but haven't tackled putting it back together yet, so no photos of that.) But for some odd reason, I missed taking photos of the process for setting the pinion preload, which involves pressing the head bearing onto the shaft, doing a trial assembly, measuring the torque to turn the pinion (should be 15 to 18 INCH-pounds), then taking it all back apart and trying a different combination of shims. Because the new bearings were slightly different than the old ones, I went through that process something like 20 times before finally getting it right. Oh yeah, it's really tough to get the head bearing off without ruining the shims, so I went through a lot of shims, too.

And there may be damage to the housing that is not visible to the naked eye. Although uncertain, it appears that was the problem with my non-LBC diff that almost set the car on fire (someone saw the flames and called the fire department), and failed again less than 1000 miles after the professional rebuild. Evidently the tubes were no longer in-line with the pumpkin, and the first rebuilder had not checked that.

Uncertain parts quality is another issue. I made the mistake of ordering the "no-name" bearings and discovered that not only were they different thickness than the originals (greatly complicating the shim selection process), they were actually different than each other! (I threw them away and bought Timken. Hopefully I got genuine Timkens, not some of the Chinese fakes that are floating around.)

Plus, chances are that you can pick up a good used rear end for less than the cost of just the R&P set new. The R&P are still available new (which I find amazing), but they sure aren't cheap! By contrast, every single "parts" TR3 that I've come in contact with had an apparently good differential in it. I've got two or three laying around, but unfortunately did not take good care of them, so condition is uncertain.

Pat,

Sorry to hear of your experience.

I'm in the process of restoring a 1959 TR3 (TS43919L).

It's a nice survivor with 56K actual miles. I'm the 2nd owner.

There are many options when restoring, especially a survivor.

Does one just drive it until something breaks then teardown/repair/rebuild/repace it?

Or do you selectively teardown/inspect, then/repair/rebuild/replace only suspect or
known faulty components?

When I came to the DRIVE TRAIN I did a lot of thinking & research.

I prioritized the REAR AXLE because I don't have the special tools, the knowledge,
the experience or the strength (I hate to admit that one) to accomplish this myself.

I removed the REAR AXLE & hauled it to Macy's Garage in Tipp City, OH.

It cost me some bucks but I think the rear axle will probably out last me (I'm 79 yrs old).
There are two other factors that are pertinent to my situation.

1. The car will be a gift to my eldest grandson & one of my goals is to gift him with a
safe, reliable (as much as possible) antique British automoble.

2. Hopefully, the future value will be greater if/when he decides to sell it knowing the
REAR AXLE overhaul was performed by one of the the premier Triumph specialty
shops in the USA. Even if not, it may help in the selling process.

Tom & Randall's input is valuable.

PS When I picked up the REAR AXLE, Mark Macy & his mechanic reviewed the original
parts (largely bearings) with me. There was some normal wear on the gears but they
installed all new Timken Bearings.

Mark also told me something that made this old engineer think. He said there were grooves
(very minor) in the axle shafts due to the grease seals rubbing. You wouldn't think soft material
could create a groove in steel?

I'm not suggesting you go this route, just sharing with you the route I took & why I took it.
Hope there is something of value here for you as you ponder your options.

mgf

I had a similar failure on my TR3. Had the ring and pinion replaced along with bearings by a local shop. I opted to use a new set of 3.45's ( like found in a TR250). Despite having little faith in the shop they did a good job and the car is still on the road some 20 years later. Since then I have converted two additional cars to the 3.45's. One was done by a friend / mechanic and LBC owner and the other by yet another local shop. Again both of those cars are doing fine after several thousand miles. By the way the gear sets I used were from TRF and came from Italy. I understand there are other sets out there from Germany but they require some machining to be able to use them.
Charley

Bummer. I would not mess with that rear end. Try to imagine the loads placed on the parts as the broken teeth grind between the gears. There are very cheap diffs available that have not been traumatized. I have 2 spares...and would be happy to donate for local pick-up.

If you rebuild the original...all the internal bearings are toast, along with the gears. The chunk needs to be checked for warpage...and it and the center hub need to be magnifluxed. All in all, a new, used dif would be cheaper and less risky.

mgf said:

Mark also told me something that made this old engineer think. He said there were grooves
(very minor) in the axle shafts due to the grease seals rubbing. You wouldn't think soft material
could create a groove in steel?

Click to expand...

I've pondered that as well. Might be mistaken, but what I think happens is that various kinds of particles get embedded in the soft material, effectively turning it into something similar to a diamond lap. Around here, we get a lot of broken sand particles in the air (caused by wind in the desert whipping the sand around and fracturing the grains into pieces small enough to float). Sand is mostly quartz, which is much harder than steel; and the fractured grains are extremely sharp (like broken glass). Other sources of broken sand (aka silica) in the air include tires on pavement and almost any kind of construction or demolition that involves concrete.

Or not, I'm just guessing.

Interesting analysis, Randall.

The car spent the bulk of it's life (49 years +/-) in the Cape Cod area. The fuel pump glass bowl contained sand. The sand had settled out in layers, probably by specific gravity, but it displayed it's difference by color! I found other evidence of sand as I proceeded with tear down & inspection.

mgf

Thanks to all of you for the advice and ideas. I'm going to drop the rear end at the shop tomorrow and see what they have to say. I'm also looking to source a used rear end here in NorCal - Let's see what that will set me back. My priorities are reliability first and cost running a close second. Here's a photo of what I dug out of the diff case. My axles looked great. The bearing had huge wear - I could grab the crown gear and move it around a bit just by tugging on it. Let's see what the diff shop has to say about this. The crown and pinion gearset plus good quality bearings is pretty costly, before one considers labor.

Pat

charleyf said:

I opted to use a new set of 3.45's ( like found in a TR250).

Click to expand...

Don't you mean TR5? AFAIK the TR250 came stock with 3.7 to suit it's less powerful "smog" motor.

TR3driver said:

Don't you mean TR5? AFAIK the TR250 came stock with 3.7 to suit it's less powerful "smog" motor.

Click to expand...

Randall,
True they were on the TR5. With all of the power in our TR 3,4 and 6 engines I don't know why they didn't use or offer them in more cars. But then I like it best for the little extra it gives me on the freeway and open road.
Charley

I believe the TR6 also got 3.45 in the rest of the world (with fuel injection), along with the 2.5 saloon and some others. The 3.45 "Stag" diff I was sold turned out to be from a 2.5 Estate I think it was, which as it turns out takes one different bearing.

But I have to say it wasn't very pretty with the later Stag low compression "smog" motor and the heavier car. Noticeably slower off the line, and the Stag really needed a bigger motor anyway. If I ever do get around to rebuilding the early motor (to UK specs of course), I'll probably swap the 3.45 diff over to it.

But I still plan to put 3.45 gears in the TR3, Real Soon Now. It has shorter than stock tires, though, so the 3.45 should bring me back to just about the original overall ratio.

Hi Pat, I can send a note to the Triumph Travelers club email list to see what they have available. Though I am a long time TR owner, I only recently joined the club. I already scored some other parts from club members and understand there are folks with extra back up parts. If I hear back regarding an available rear end, I will let you know.

PatGalvin said:

Thanks to all of you for the advice and ideas. I'm going to drop the rear end at the shop tomorrow and see what they have to say. I'm also looking to source a used rear end here in NorCal - Let's see what that will set me back. My priorities are reliability first and cost running a close second. Here's a photo of what I dug out of the diff case. My axles looked great. The bearing had huge wear - I could grab the crown gear and move it around a bit just by tugging on it. Let's see what the diff shop has to say about this. The crown and pinion gearset plus good quality bearings is pretty costly, before one considers labor.

Pat
View attachment 45104

Click to expand...

I recall a local used TR parts guy was clearing out his stash and giving away TR rear ends because no one ever needed them (well, almost no one). I may yet regret it but I passed on the offer. Anyway, you might contact Marv Gruber as a source if you go that route.

mgf said:

...there were grooves (very minor) in the axle shafts due to the grease seals rubbing. You wouldn't think soft material could create a groove in steel?

Click to expand...

The Grand Canyon was created by water.

Finger crossed for a good used one Pat

mgf said:

Pat,

Sorry to hear of your experience.

I removed the REAR AXLE & hauled it to Macy's Garage in Tipp City, OH.

It cost me some bucks but I think the rear axle will probably out last me (I'm 79 yrs old).
mgf

Click to expand...

For what it's worth, I did the same on my 4A. It cost more than a few bucks (four figures), but the job should be done well (car still a while from being on the road).

It is possible to rebuild oneself. But my personal situation is one where (1) getting the car on the road is a priority (it has been 10 years already!), and (2) I'm not sure I want to delve into something this complex, much less invest in tooling / additional time to make some custom tooling. I figured my time is better off spent on other projects, like reassembling the car!

Update on my rear end problem.:chuncky: Thought you all might like to know how this is going.

I pulled the diff and dropped it at Ring and Pinion Service here in Rancho Cordova (Sacramento). They went through it and told me it was rebuildable. They seem like a great shop and have done some British cars before. I do have a lot of confidence in them. I purchased a new ring and pinion set from Rimmer Bros for about $325 delivered (strong dollar and 15% off sale worked well for me). I was able to obtain all Timken bearings from TRF, along with some shims and pinion seal. All that, with $350 for setting up the new diff and I'll be back on the road in a week or so (I hope). As info, this is about a grand for a rebuilt rear end. I had an opportunity to buy a used rear end for $600 locally and had some offers from others to give me one (with shipping probably at a few hundred dollars). But, I am opting to pay the piper and have what I hope is a solid reliable diff that will outlast me and the car. I sure didn't want to spend the money but now can relax and not worry about it any more. It is the only part of the drive train that didn't get a full rebuild during my restoration.

Thanks for all the great tips and offers for assistance.

Pat

Did they have any idea what happened to the tooth that broke?

Hi John

I think I had a bearing failure that led to a misalignment and caused a tooth to break. Then, all **** broke loose in there. I did have some whining and vibration from some part of the drivetrain before the rear end failed completely. Here is a pic of the pinion gear that they returned to me from the shop.
They just completed the rebuild. I installed the diff and most of the trim yesterday afternoon/eve. Something really interesting that I learned from this experience.
New ring and pinion gears have rough surfaces on the gears. They require a break in period. The rough surfaces need to wear in (mate) together and generate a lot of heat during that time. They recommended that I drive 20 miles and low loads and below 45 mph and then let it cool for an hour. Repeat the drive and cool for a total of 4 cycles. Then, complete the driving up to 500 miles but still under light load. Then drain and fill the diff. During break in, there is a lot of generated heat - if you just started driving on the highway without the cool cycles, the oil would overheat, fail, and you would burn your ring and pinion gears. This is the required procedure for the shop warranty (although I don't get the warranty because I brought in my own parts). Pretty interesting, no?

Pat

PatGalvin said:

New ring and pinion gears have rough surfaces on the gears. They require a break in period. The rough surfaces need to wear in (mate) together and generate a lot of heat during that time. They recommended that I drive 20 miles and low loads and below 45 mph and then let it cool for an hour. Repeat the drive and cool for a total of 4 cycles. Then, complete the driving up to 500 miles but still under light load. Then drain and fill the diff. During break in, there is a lot of generated heat - if you just started driving on the highway without the cool cycles, the oil would overheat, fail, and you would burn your ring and pinion gears. This is the required procedure for the shop warranty (although I don't get the warranty because I brought in my own parts). Pretty interesting, no?

Pat

Click to expand...

That may be the best available today; but the factory gears were supplied already lapped to match.

Which bearing do you think failed? That head bearing looks OK and it's usually the one that takes the most pounding.

All of my failures have been from breaking teeth. Once part of a tooth gets broken off, it quickly does some incredible damage to everything else. When this one happened, I didn't even realize I had a problem until I saw gear oil running down the driveway.