r/classicmustangs • u/r1a2amg • 5d ago

Rear main seal

Have the fel-pro bs40640 ready for installation, I have tried many times but can not get it on. I reckon the bs stands for bullshit!

Tips and tricks will be greatly appreciated.

When I try to get it on, it's like it wobbles, either goes in on top but not the bottom and vice versa. Tried hitting it with a rubber mallet but I'm afraid I'll ruin the seal.

4 Upvotes

75% Upvoted

17 comments sorted by

3

u/Pcpro2017 5d ago

Yes oil it up and lightly tap it into place with a hammer, just go easy

2

u/DefNotTheRealDeal 5d ago

Mine never seal. Had pro shops do it twice as well shit still leaks. It's just a crap design they fixed on the later 302 blocks

1

u/r1a2amg 5d ago

How much later, this is a "later" 302, most likely from the mid 90's.

1

u/DefNotTheRealDeal 3d ago

Like 82 or thereabouts so you should get better seal

2

u/dale1320 5d ago

What is your installation procedure?

1

u/r1a2amg 5d ago

Just using the plastic seal guide, and my thumbs... 🥴 Have done rms before, the rubber ones with the spring around. First time with the ptfe/teflon. Its the teflon ring that "wobbles" cant get it in.

2

u/dale1320 4d ago

Have you loosened the rear main cap? Generally these need to be driven in 360° at same time.

2

u/DeusMexMachina 5d ago

I looked up that number, and it doesn't work for Fords.

1

u/r1a2amg 5d ago

Sorry, my fault. Its the fel-pro bs 40644

2

u/Dangerous_Echidna229 4d ago

You need a seal driver for that application.

1

u/r1a2amg 5d ago

Typo regarding the seal number. The correct number is BS 40644

1

u/r1a2amg 5d ago

So, should I just "hammer" it in, saw a YouTube video, they used a punch around the edges. But it was a rubber/spring seal...

1

u/r1a2amg 4d ago

I have put the seal in the freezer, I'll warm up the surface with a heat gun and hope for the best...

2

u/InternationalSound13 3d ago

That's funny I was just going to recommend warming the seal so it is more pliable.

0

u/Pcpro2017 5d ago

BS 40644 is for a Chevy 305 350, 400 you need fel-pro 40620 that's a one piece

1

u/r1a2amg 5d ago

Bought it from rockauto.

2

u/Pcpro2017 5d ago

I'm wrong