Rear Main Seal Teflon VS. Rubber

Discussion in 'Fox 5.0 Mustang Tech' started by gregpro50, Apr 3, 2005.


  1. gregpro50

    gregpro50 New Member

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    Fel-pro makes two rear main seals. One is teflon, one is rubber. What is the difference other than price ?? I just replaced mine and the ****ing thing is still leaking. I thought it fixed it but after I drove it today I see it is leaking again. I am in the process of pulling out the tranny right now to investigate.
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  2. Allforspeed

    Allforspeed New Member

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    i just got the normal rubber one from summit when i re did my clutch the other week and its fine, i did use the silicone sealant on it, you can search on here and see tons of posts/threads about how to do the damn rear main seal right. the teflon one is probably better/more durable but summit was out of stock and i needed one by that weekend, if i did it again i would probably use the teflon one. good luck, pm me if you have any questions or if i can help
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  3. tunedin302

    tunedin302 I AM the law!!!

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    I used the teflon. The actual teflon is only on the area where it touches the crank. I imagine the teflon is more beneficial becuase less likely to weara groove in the crank. I'm sure someone will chime in with an answer though.
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  4. Rick 91GT

    Rick 91GT SN Certified Technician Site Sponsor

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    The Teflon also takes the heating and cooling cycles better.
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  5. 5spd GT

    5spd GT "the 5.0 owns all" Founding Member

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    I would think the Teflon is less resistant on the crank shaft compared to the more frictionized rubber:shrug: Sound about right?

    Anyways...I just had my mechanic install a rubber rear main on my car (I tried and failed so I paid someone to do the work)...and he said he does not use silicone on "our" iron blocks but only on aluminum blocked areas where the rear main seal goes like on Hondas for example. (do to the stretching and flexing the aluminum can do). I do know that his method didn't leak over mine but I also know he did it and not me:)
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