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View Full Version : TR2/3/3A TR3 crankshaft rear main seal opinions wanted.



mallard
07-18-2009, 08:48 PM
I was at the machine shop today checking on the condition of the engine and found that the mains are good but the rods need help. So I'm looking at an .10 grind on the mains and .20 on the rods. My crank has not been turned for the new style rear seal, and I'm not sure if I want to do it. I do have access to the alignment tool for the original seal but I'm looking for ideas from what others have done.

tinman58
07-18-2009, 10:44 PM
I had the new style installed and after 2000 miles I pulled off the flywheel for the toyota transmission conversion and not a bit of oil leaking at all. I am sold on it . Now I have to change the oil pan gasket that is leaking.
Dan

martx-5
07-19-2009, 06:28 AM
I opted for the original style scroll seal when re-doing my engine, and I have NO leakage back there. The trick is to properly set up the seal.

If you have an alignment tool, I would measure it, as the dimension needed to get the scroll to work is critical. The tool offered by Moss is too large...larger then what is recommended in the service manual...which is generally regarded as also being too large.

You can read more about it in this thread. (https://www.britishcarforum.com/bcforum/ubbthreads.php/ubb/showflat/Number/453510/Searchpage/2/Main/45593/Words/crank%2Bseal/Search/true/Re_Rear_main_Scroll_Seal#Post453510)

TR3driver
07-19-2009, 09:41 AM
I've not reached that point yet myself; but with all the horror stories I've heard, I'm thinking I should not have had the scroll ground off. Lots of folks report the "high tech" seal leaks even more than the old scroll.
https://www.socaltriumphs.org/docs/mainseal.htm

Of course the problem is not helped by the fact that many kits went out with incorrect instructions. The diameter given for grinding the crank was too small (which of course means a new crank to correct).

The problem is bad enough that Darryl at Racetorations is working on a new conversion; which will use a one piece seal (and a removable flange for mounting the flywheel to the crank).

Moseso
07-19-2009, 11:48 AM
I used the scroll seal and it works fine.

Having heard all the warnings about the plastic seal setting tool, I checked the one I got, and found that the seal didn't fit it. I took it to the guy who was doing my head. When he chucked it in a lathe, we found that the two diameters weren't concentric, either. In a word: useless.

This procedure works, if you don't have a lathe to make your own seal setting mandrel. Wrap the crank journals with one thickness of Teflon pipe thread tape. Do the same with the scroll on the crank. I can't remember how many thicknesses were required there, but experimentation is easy. Put some on and hold the seal in place on the scroll. It's right when you can squeeze the two halves together, and detect no movement relative to the scroll. Once the crank is properly wrapped, bolt it in the block with the bearings, and set the seal on the block and end cap. Take the crank back out and clean off all the Teflon tape. You're ready to go.

The idea is to center the crank in its bearings, the way the oil will when it's running, and center the seal around the scroll. The Teflon tape is an easy way to do that -- and it's cheap! If you get a little too much in the bearings, it will just squish like plastigage - but all the way around the journal, holding the crank centered in the bearing.

mallard
07-19-2009, 04:46 PM
Thanks for all the info and the links. Right now I'm leaning in the direction of the scroll seal. You can't reverse the other option.

trfourtune
07-21-2009, 11:02 AM
make sure you have the crank nitrided. The "new" seals can be made to work according to "Uncle Jack" and Tony Drews by shortening the spring on the seal. See Tony Drews web site.
https://www.tonydrews.com/uncle_jacks_engine_building_tips.htm
Rob

sp53
07-21-2009, 03:35 PM
Hi Keith I went will a stock crank seal and have had no problems. There is a nice chapter in one of my books on how to do it, but i need to get the name of the book; it is a small yellow tr3 hand book. Anyway I used the original seal and packed in the “Indian Head “gasket shellac with the felt. You basically build a dam on the rear cap with the shellac and felt. Keep stuff really really clean and let the shellac cure; that is how they were done new. My original aluminum shells had very little wiggle room to use a tool. The bolt holes were so tight that even if I had a tool I do not think it would have worked, so I opted for equal reveal. I basically was forced to put it back the way it came apart because of the bolt pattern. I was committed probably within thousands. I think the original had the holes slotted just enough for proper alignment.
Steve

mallard
07-21-2009, 07:56 PM
Thanks for the additional information.