How to cut rear main seal for proper crush

I am doing a rear main seal for a friend and I was checking the seal today to cut and I am second guessing myself. First I want to make sure that I want .010-.015 on each half. Also as title says how are you guys cutting the seal. When I checked it today I will probably be cutting a max of .015 off the seal. I can do the rubber part but how do I cut the metal ring that precisely. Also I am doing this without tearing the engine completely down, is it possible to cut both seals off the cap or do I have to measure the seal that will be in the block in the block( I know what this answer will be just hoping for the easy way). Appreciate any help you can give me, I am usually confident in what I am doing but this has me jumpy as I don't want to have to do it a 3rd time...

plowboy34 wrote:I am doing a rear main seal for a friend and I was checking the seal today to cut and I am second guessing myself. First I want to make sure that I want .010-.015 on each half. Also as title says how are you guys cutting the seal. When I checked it today I will probably be cutting a max of .015 off the seal. I can do the rubber part but how do I cut the metal ring that precisely. Also I am doing this without tearing the engine completely down, is it possible to cut both seals off the cap or do I have to measure the seal that will be in the block in the block( I know what this answer will be just hoping for the easy way). Appreciate any help you can give me, I am usually confident in what I am doing but this has me jumpy as I don't want to have to do it a 3rd time...

I use a ring filer when building the engine in the first place ... how you would do this afterward I guess, is taking the entire amount off from one half only.

Just to make sure I understand you right your saying something like make the main cap flat on both sides and have the .020-.030 sticking out of the block. If so have you ever tried this before. Also can't believe I didn't think of a file to use..... I appreciate the help Randy

plowboy34 wrote:Just to make sure I understand you right your saying something like make the main cap flat on both sides and have the .020-.030 sticking out of the block. If so have you ever tried this before. Also can't believe I didn't think of a file to use.....  I appreciate the help Randy

I have never fit a rear main seal after building the engine and done just one half; but, as long as it gets round, (not slightly oval), and not compressed excessively so it still seals correctly, it shouldn't make any difference.
If you look at the seal ends closely, the lip tips are angled at the parting lines, one side down and one side up.  I never remove any material from the protruding lip side.

.014" to 020" is about right.

Thanks for the help Randy....after staring at seal for probably 20 minutes I finally seen what you are talking about. The seal in cap actually isn't to bad but the one in the block sticks up ridiculously high...hopefully I can get this right

I can't recall ever needing to cut a modern seal for fit

dfree383 wrote:I can't recall ever needing to cut a modern seal for fit

Same

Can't you stick the seal in the block measure how much you need to take off then stick it in the cap as a reference file how much you need off then install that half in the block then just do the other half in the cap and install that

It was easier than I thought it was gonna be. I loosened up the back three main caps which let the crank raise up enough that the seal went in easy, was able to measure and mark seal easier than thought also then removed seal cut and filed and reinstalled. All seems good so hopefully did correctly and there will be no leak.

richter69 wrote:

dfree383 wrote:I can't recall ever needing to cut a modern seal for fit

Same

I am guessing that you guys have not assembled many "line honed" blocks.

Just did, my old a460 block was also. No issues.

I did my 460 last year with the Ford Motorsport gasket kit seal, before I read the stuff about the seal being too large, and it leaks, block not line honed.

I never had a problem with them back in the 90's when we were bracket racing using the same seal and never measured them, and were probably a lot less careful building them.

richter69 wrote:Just did, my old a460 block was also. No issues.

If it doesn't leak, you're lucky.
Of course engines running with vacuum in the crankcase probably won't leak.

rmcomprandy wrote:

richter69 wrote:Just did, my old a460 block was also. No issues.

If it doesn't leak, you're lucky.
Of course engines running with vacuum in the crankcase probably won't leak.

Can you run a vacuum pump on a street car?

Oh

richter69 wrote:Just did, my old a460 block was also. No issues.

It ain't got shit to do with if a block has been honed at the main housing bores.

It has every thing to do if the caps have been cut and worse yet if someone cut them too much.

With a typical new A460 block the honing is to get the bore to the 'high' side...in that case the caps should never have to be 'cut'.

true, i dont recall... seems he trimmed the caps a "touch" .... either way it wasnt excessive.



one piece Kasse seal ftw......

Which raises the question, Has anyone tried the one piece Kaase seal ?

Would it not be affected similarly ??

Anyone had issues with a motor sitting ? Motor was engine run-in , tuned + dyno'd  for 2 days , not a sign of a weep . Sits for 2 years while the car is finished , now weeps on first start up . Hoping it seals up with some heat

It was measured for crush during assembly also and was ok

I had never heard of cutting a rear seal either until a couple months ago. I built a engine for a good friend a couple years ago and the rear seal dripped a little. Wasn't nothing bad and he said as long as it didn't get any worse it was ok(it aggravated me). Fast forward to a couple months ago had to tear motor down for other reason and I told him let's just pull engine and redo seal while we're at it. After that it leaked bad, I just happened to see the article on this and thought hey maybe that's my problem. When I unbolted the rear cap this time it popped up a little like it was spring loaded. When I put new seal in it was crazy how much it stuck out so I cut it to Randy's specs which I had to cut at least .020 off. Now to get engine back in and hope no leak. The End

Ive never had any problems in the past, but after reading this thread i will check every one i do a lot better from now on.

Gregaust wrote:Which raises the question, Has anyone tried the one piece Kaase seal ?

Would it not be affected similarly ??

Anyone had issues with a motor sitting ? Motor was engine run-in , tuned + dyno'd  for 2 days , not a sign of a weep . Sits for 2 years while the car is finished , now weeps on first start up . Hoping it seals up with some heat

It was measured for crush during assembly also and was ok

I sent Fabio one of the new Kaase seals....I'm not sure if the crankshaft has been installed yet.

Naw its still in the box...

I put one of Kaase's seals in my new engine, have not run it yet.