View Full Version : TR4/4A TR2-4A new main seal question

03-09-2012, 06:38 PM
I got one of those new rear main seals, the one that utilizes the original scroll seal, adding a neoprene or rubber-type seal to a groove cut in the aluminum.

Has anyone replaced this without removing the engine from the car? I am pulling the transmission to replace the clutch, and have the car on ramps, and would like to avoid pulling the engine if possible. I will also be replacing the oil pump.

Dan B

03-09-2012, 06:43 PM
Check Rear seal (https://www.britishcarforum.com/bcforum/ubbthreads.php/topics/812900/TR3_Rear_Main_Seal)

03-09-2012, 07:27 PM
Aloha Dan,

I ahve installed the rear main seal developed by Mad Marx. This is the one that does not require the crank shaft to have the scroll machined off. I bought it from TRF and the two piece aluminum rear seals come with the machine work done. To properly mount and align the replacement machined aluminum rear seals that will accept the vitron seal the crank needs to be removed for the centering mandril to be used. Here is the text from the installation instructions:

"Installing of the Crank split lip seal

What is this all about?
The main idea is to have the best of both – the wear free stock seal that will last ages – and the split lip seal ring that will catch oil that is leaking through the stock seal assembly. So even when the rubber seal fails the stock seal will remain intact and will continue to work.

This split lip seal is made to run besides the scroll of the stock crank so there is no need of reworking the crank to fit the lip seal. Only the aluminum stock seal has to be reworked on a lathe which is quite a low cost conversion compared with grinding the crank which is needed for other lip seal conversions. The lip seal is made out of VITON. This stuff can stand high temperatures and high surface speed that might occur on a crank at maximum revs. So this lip seal is made for racing purpose.

VITRON seal, 71.38mm ID, 88mm OD, 10.5mm wide

1. Changes to the stock aluminum seal ring
The ring has to be changed as shown. It will be easier to use a centering tool but to clamp it to a lathe chuck is in most cases precise enough. The diameter that keeps the lip seal later has to be concentric to the scroll inside.
Chuck with a holder to center the ring All measures are in [mm]
The draining hole of the aluminum seal will be blocked by the new lip seal so you need to enlarge the draining area as shown. Use a press drill and a high speed grinder with cutting tools to do that job. Take care not to damage scroll and don’t grind through the sidewall or a bad leak might occur. Enlarge the fixing bolt holes of the aluminum ring to have chance to center it properly.

Preparing the crank
Not much has to be done to the crank. Just remove dirt and roughness of the surface on which the lip seal will run. Slightly polishing would be the best but is not mandatory.
Assembling of the crank and the lip seal to the block
1. First clean all parts with brake cleaner and dry it thoroughly.
2. Use an alignment tool to fit the stock aluminum seal properly to the engine block. The factory manuals have the same CRITICAL error. The alignment tool drawing where the tool fits inside the seal in the factory manual needs to be changed to 71.57mm [2.818”]. A mistake
3. Use silicone liquid gasket to seal the aluminum ring to the block.
4. When installing the aluminum ring to the bearing cap take care that you don’t block the draining hole with silicone. Put a paper tupe inside the hole while you installing the ring. It is mandatory for a proper function of the lip seal that the draining hole is open to relive the oil into the sump.
5. Next step is to center the aluminum ring with the still flexible silicone.
6. Put the bearing cap in place to the block with the centering tool inside and torque up the bearing cap bolts. Tigthen the aliminum ring bolts sligthly. Tap the aluminum ring halfs gently into place. Tighten the fixing bolts of the aluminum ring more and tap again. After that torque them up.
7. Install the lip seal to the crank. The spring can be openend closed to be wrapped around the crank journal. Becareful with the spring. Fit the lipseal at the journal area and put the spring into the notch of the lip. Open the ring carefully and slip it over the scroll area. Take care not to damage the lip seal with touching the sharp scroll edges. Put a little smear of silicone on the contact face where the lip seal closes to have a better seal. Use a small wood or screw driver for this job.
8. Install the bearing shells to all mains. Oil them. When putting the crank to the block take care that the split of the lip seal is showing towards the cylinder head. When the crank has its rest on the bearings push the lip seal towards the aluminum ring. Use a larger screw driver for this job. Be careful not to damage the rubber parts.
9. Put some silicone on the contact surface on the bearing cap as shown in the photo. Install the bearing cap to the engine block and torque some turns up. Again push the lip seal to the aluminum ring while you torque up the bearing cap bolt to full. Look all over that the lip seal is sitting straight in the aluminum ring. A little amount of silicone will be squeezed out of the split of the lip seal.
Congratulations – well done!
Now give a little oil from outside to the lip seal before you start your engine."

03-09-2012, 09:14 PM
I have done the same- yes, pulling the crank will ensure centering the seal. You'd need a pretty specialized setup to get it centered without pulling the crank, it has been done before by others but I think it is not an option for 99.9% of TR owners.

03-10-2012, 09:02 PM
Does it work well?

03-10-2012, 09:29 PM
I have installed the new rear crank seal from Joe Alexander racing. So far no leaks from the main. Be sure you buy twice the rope sealing mat'l When you install the rope seal the way it is supposed to be you will use twice the amount. It is all explained very well in the Kas Kastner book. When you install the rope seal you need to soak it in permatex and then BEAT it into the bearing cap with a drift pin made to fit the channel. I made one from a screwdriver and a grinder in ten minutes. Talk to joe or buy the book. It is well worth it.

03-10-2012, 09:31 PM
I've put the new seal in twice now in two different engines. First time, a couple drops. This time, everything is nice and dry. I suspect the felt seal used for the rear main may be contributing to the leak in the first case. I think the new seal is worth it and will use it again.

edit: tinman beat me to it. the seal is good, take your time with the felt.

03-14-2012, 08:10 PM
I don't see why not. I have pulled the pan, removed the transmission and flywheel, and pulled the rear main cap. The top half of the old seal rotated right off. Now I am quitting for tonight because I need to clean some parts and get some Right Stuff before I begin reassembly, but I think I can rotate the top half back up in there and reassemble. Am I missing something?

Dan B
South Charleston, WV
66 TR4AIRS EFI, 80 TR7 DHC Toasted Motor

03-14-2012, 08:41 PM
You won't be able to center it. Maybe you will get lucky, just having the new seal there may auto-center it somewhat. But with the original scroll it would be very difficult to center with the crank in place.

03-14-2012, 10:40 PM
Am I missing something?

If you fit the two halves of the seal together off the engine, you get a hole in the middle that is only a few .001" bigger than the outside diameter of the scroll. When you fit it to the engine, if one side is off so it touches the scroll, then the other side will be held away from the scroll by twice the normal clearance. Too much clearance = leak.

Maybe it won't leak very much, especially with the Viton seal after it. Worth a try, if you're the kind that doesn't mind either spending all that time and money and then failing; or doing it over again. I've done sillier things, and sometimes gotten away with it.

PS, don't forget that the crank will be higher when it's running then when it is at rest even with the rear main cap installed. Without the rear main, I'd guess it droops by another .001" or .002".