Flex Plate Upgrade

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Sep 24, 2023 | 10:50 PM

35thredz28

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Cruising

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From: Oklahoma

Flex Plate Upgrade

Good evening,

Looking to upgrade the flex platte on a 98 c5. Will the B&M 20340 work for this upgrade?

Also, is there an adapter plate that is needed to attach the splined collar to the flex plate?

Thanks

Sep 25, 2023 | 05:57 PM

grinder11

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They make an aftermarket flexplate/starter ring gear that uses no pinch bolt. I can't recall who makes it. The no pinch bolt design is desirable, for a number of reasons. You may try PMing @RonSSNova for more info. He is the member who told me about it.....

Sep 25, 2023 | 07:08 PM

Smoken1

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From: Oregon

St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23

Quote:

Originally Posted by grinder11

Are you referring to the SFI flex plate and the RPM coupler?

Sep 25, 2023 | 08:13 PM

35thredz28

Thread Starter

Cruising

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From: Oklahoma

Thanks guys. I contacted RPM today and they got me squared away.

Sep 28, 2023 | 03:50 PM

grinder11

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Quote:

Originally Posted by Smoken1

Are you referring to the SFI flex plate and the RPM coupler?

IDK who makes it.

Sep 28, 2023 | 11:55 PM

35thredz28

Thread Starter

Cruising

Joined: Feb 2018

Posts: 12

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From: Oklahoma

Quote:

Originally Posted by Smoken1

Are you referring to the SFI flex plate and the RPM coupler?

Yes, that is what I was looking for.

Just received the one from rpm and its a quick time sfi flex plate. The coupler came with it but im not sure if its a piece from rpm or not.

Sep 29, 2023 | 12:27 AM

Smoken1

Joined: Apr 2013

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From: Oregon

St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23

I'm sure it is the RPM coupler if that's what you asked for

Last edited by Smoken1; Sep 29, 2023 at 02:21 AM.

Sep 29, 2023 | 04:37 PM

grinder11

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One big advantage to the slip fit splines vs the pinch bolt type is reduced pressure on the crankshaft thrust bearing. I once had a thrust bearing wear out in 30,000 miles, due to high coolant temps for an extended, 7,000 mile trip in a record heat wave. When all that aluminum gets hot, it expands a lot. This puts a lot of pressure on the thrust bearing. The FSM lists a special procedure for all the A4 C5s, and if it isn't followed, accelerated thrust bearing wear will happen. Basically, it says to get the entire drivetrain up to normal temp, loosen the pinch bolt while in the expanded position, then retighten. That's it. When the splines are slip fit, they can simply expand or contract to where they need to be.