View Full Version : TR4/4A New pinion seal doesn't fit!

12-09-2017, 02:25 PM
Just finishing the restoration of my differential. Started to install the pinion seal, and found that there is no way on earth it will fit. I bought it from TRF. The car is a solid-axle TR4A.

The seal's OD is 2.690 inches, and the opening at the front of the differential, where it has to fit, is 2.620. The old, original seal that I removed was 2.625 OD, which makes sense. I can't see any way this new one will go in, but maybe there is. If so, could someone enlighten me? What have you guys used?

I did a little research, and found that the seal no. 470487N is the one listed everywhere for the TR4, and I also found the dimensions in a Timken catalog (below). The TRF seal has those dimensions. It appears that the 451857 should fit; it's nitrile instead of polyacrylate, and there are small differences in the style of the seal. I don't think those differences are significant, so lacking any other suggestions, I think I'll get one of those.

12-09-2017, 03:51 PM
Assuming that you still have your old seal, why not take it to your local bearing shop and have them replace it.

12-09-2017, 04:34 PM
Is the outer rim of the old seal still stuck in the case ?

12-10-2017, 12:34 AM
No, the case is quite empty, no bits of seal left. I took out the old seal, which appears to be original--it is one of the leather ones. I'm sure that, if I took it to a seal shop, it would be a real conversation piece. I suppose I should just get one of the 451857s, but it would be nice to know what's going on. I can't believe I'm the first person to notice this.

I've noticed that the 470487 is listed for TR3s and TR4s as well, so the problem doesn't appear to be that it's only for IRS cars.

12-11-2017, 12:16 PM
Well order the other one and compare. I remember the last one I put in was tight and I used some of that aviation gasket sealer for grease ( had to work kinda quickly but that stuff stays runny for a while) to help it slid in plus I had to smack it kind of hard, but it went-- plus I had to work it in a little with a block of wood and a slightly large hammer.

12-11-2017, 08:59 PM
It looks like you received a seal for the IRS diff. I measured the seal from a TR6 (same as the IRS TR4A) and it is 2.680".

12-12-2017, 12:01 PM
Thanks. I kinda thought that might be the case, but I don't have an IRS car near me to see. the seal I bought is specifically listed in the TRF catalog as being for the solid-axle TR4As. I've exchanged a few emails with their customer service, emphatically recommending that they change the catalog. They promised to send me one of the seals for the earlier cars. Also, I bought a 451857, which arrived yesterday. I'll compare it to the new one I get from TRF, then post the results--and also let the people at TRF know.

12-15-2017, 11:13 AM
Just a follow-up: I went ahead and installed the 451857. It fits perfectly.

TRF is sending me another seal, a different part no. It's listed for some of the earlier solid-axle cars; I'll bet it is actually a 451857. I should receive it in a few days. We'll see.

12-16-2017, 01:24 PM
According to the parts catalogs, solid axle 4A should take the same seal as IRS; which is different than the earlier solid axle.
Is there any chance that what you have is actually an earlier axle, possibly with the bracket for the bump stop added?

12-16-2017, 04:52 PM
Moss and BPNW list different numbers for the solid axle and IRS diffs (520-100 for IRS and 520-090 for solid axle) pinion seals. In the infamous words of Henry Lee, "Something not right here"
According to the parts catalogs, solid axle 4A should take the same seal as IRS; which is different than the earlier solid axle.
Is there any chance that what you have is actually an earlier axle, possibly with the bracket for the bump stop added?

12-16-2017, 06:41 PM
Just for grins, here are the listings from the factory SPC (2nd edition in both cases). First TR4A, then TR4



12-17-2017, 01:12 AM
Hmmmm....the plot thickens.

In a 50-year-old car, anything is possible, but I don't see any indication that the axle has been replaced. The crud layer on it was much the same as the rest of the car, and all the bits, like the mounts and handbrake-cable supports, are like a 4A. Finally, this car appears to have been left alone and neglected for decades. I can't imagine someone who doesn't even care much about basic maintenance changing out a rear axle.

I received the seal from TRF yesterday, and it clearly would fit, but it's not the 451857. It is the one they sell for TR4s; their part no. is 100898. My best guess is that there is an error in the parts manual, and TRF and others used that info to stock their parts.

12-20-2017, 10:31 AM
This winter I am going to replace the pinion seal on my solid axle Tr4a. I was looking up the part on the Revington TR site, and they have this note listed with the part:

The Original Triumph TR4A parts catalogue does not list the Axle Pinion Seal correctly in so far as seal 140337 is listed for both the independent suspension axle unit and the live axle unit.
Seal 100898 is approximately 2mm smaller in outside dia than 140337 and fits the live axle.
Seal 140337 fits the independent suspension axle


12-20-2017, 01:06 PM
It is strange that TRF has never corrected their listing after all these years.

12-20-2017, 07:25 PM
Jim, that's interesting--I had missed it. But it confirms what I suspected.

In other news, I wrote back to the helpful customer service guy at TRF, thanked him again for sending the correct seal, and gave him the link to this thread.

12-20-2017, 08:21 PM
I stuck a note in the PDF I maintain ...

12-22-2017, 12:55 AM
Not really adding much to the conversation I guess, but I have a fuzzy memory of the same thing happening to me with my TR4A solid axle. Probably close to 20 years ago or more. Don't remember the vendor, but I usually order from VB or TRF. But I guess that is consistent with the factory manual mistake on the part number.

12-24-2017, 09:52 AM
FYI - here's the link to the pinion seal comment I mentioned on the Revington TR site:


BTW - if you search their site for their "thin belt" pulley conversion kit, they have an interesting note regarding the use of harmonic balancers (they say it is not necessary).


12-24-2017, 11:51 AM
(they say it is not necessary).

Wonder if they will pay for my broken crankshaft ?

12-24-2017, 12:35 PM
its kind of a long article so I won’t copy and paste it here. However, here is the link:


Click on the FAQs tab above the part listing. It’s an interesting read.


12-24-2017, 02:45 PM
Thanks, Jim. But that wasn't my point at all (I've seen it before).

Point is, he (Neil Revington) is trying to sell a product; and in the process, claiming it is "just as good" as a more sophisticated product. That's his opinion, and he is certainly entitled. But he isn't going to back it up by replacing any crankshafts that happen to break while using his product. And he might possibly be just the least bit influenced by the money he makes selling a less sophisticated product.

I used to agree with him; in spite of all the broken crankshafts I've seen. Then mine snapped, while I was running without any dampening. Could be unrelated, certainly. I can't prove anything. But I'm going to use a damper on the 'new' crank, just in case. BTW, that was also Ken Gillanders' opinion; that running a damper will help reduce crank breakage.

Something to try: Hold up a TR crank supported by a wire or similar, and strike it like a bell. It will ring (unless it is already cracked). Now try again while touching it with the other hand. It either won't ring at all, or the sound will be much, much softer. Is your hand designed to eliminate specific frequencies, that just happen to match the fundamental resonance of the crank?

This isn't my photo (don't have mine out of the car yet), but shows a break very close to where mine is. The funny part is that normally, I would expect maximum stress to be at the rear; where all 4 cylinders are fighting against the flywheel and drivetrain; rather than at the front where the only load is the timing chain.