SD4 clutch solution (Page 1/1)
IMSA GTU APR 05, 08:53 PM

I have 3 SD4 flywheels, (from left to right; stock, light weight, ultra light weight) I know they're like owning gold. None are for sale, please don't ask. They use a 7.25" clutch and I cannot find the "right" clutch, I have reached out to Quarter Master Industries who originally made these flywheels and clutches with original part numbers and I had no success, they couldn't even get back to me so after extensive research across the internet and running all over to speedshops and places that specialize in circle track cars I'm left at a dead end.

Here's the situation, the M17 Muncie has a 14 spline. The old Quarter Master clutch they used to sell would of worked. Now Quarter Master or any other brand that makes NASCAR 7.25" clutches either come in a 10 spline or a 26 spline. I've seen the builds across Pennocks where people adapt other flywheels and clutches to work on the SD4 and I don't want to go that route, I want to keep the small 7.25" clutch for obvious reasons. So as my last resort what I'm going to do if a 14 spline 7.25" clutch doesn't exist anymore is simple. I'll take the transmission apart and pull the output shaft and get it remade into a 10 spline at the machine shop I have access to so I can use these newer style clutches on the old flywheels. That's about all I could do at this point right? It would make more sense in the long run as compared to getting a custom clutch made because then parts are readily available as 10-26 spline are just available compared to having someone make a custom clutch and then going out of business say 5 years later and I'll be in the same situation again.

I can give out original part numbers if you need them to help me, thanks.
RAREW66 APR 05, 10:51 PM
Have you considered having the existing disk and/or pressure plate rebuilt? There are several shops that specialize in relining obsolete disks. Some offer hub changes. Look up "ANTIQUE & OBSOLETE CLUTCH REBUILDER " on an internet search.

Fred
IMSA GTU APR 06, 08:10 AM

quote
Originally posted by RAREW66:

Have you considered having the existing disk and/or pressure plate rebuilt? There are several shops that specialize in relining obsolete disks. Some offer hub changes. Look up "ANTIQUE & OBSOLETE CLUTCH REBUILDER " on an internet search.

Fred



That’s the problem, I only have the flywheels. No old clutch either, otherwise I’d go get it rebuilt. Can’t imagine anyone has a original clutch sitting in their garage to sell as a core to me.
fierosound APR 06, 06:15 PM
Did you look at Tilton?
https://tiltonracing.com/pr...ic-clutch-disc-pack/
https://www.competitionsupp...8-rivet-driven-plate
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[This message has been edited by fierosound (edited 04-06-2022).]

KissMySSFiero APR 07, 07:53 AM
Try a custom clutch builder.
I stumbled upon Kentucky Clutch when researching clutches myself.

https://kyclutch.com/

Apparently its the goto for some of the ecotec crowd.

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IMSA GTU APR 07, 12:17 PM
Thanks for links, it’s helpful to narrow down a decision. I’ll make some calls and see what I can do. I’ll keep this updated in the future with what I decide to do just in case someone has the same situation down the road