Trouble finding clutch parts

[Funky61]

I ordered the Perfection Driveline 04-528 directly from them, and they only had the one in stock. It is listed in their catalog as fitting the 305 and 351 six cylinder.

It looks a lot like the photo of the M-Pact 04528, but it looks like it will not work.

So am I correct that this will not fit?

[BobBray]

I don't think that disc will work. This is the same old problem, the hub protrudes out too far on the flywheel side and hits the pilot bearing.

[jerrspud]

Originally Posted by Funky61

I ordered the Perfection Driveline 04-528 directly from them, and they only had the one in stock. It is listed in their catalog as fitting the 305 and 351 six cylinder.

It looks a lot like the photo of the M-Pact 04528, but it looks like it will not work.

So am I correct that this will not fit?

disk is backwards.

these are the new numbers that fit
kit https://www.rockauto.com/en/moreinfo...=1993&jsn=1326
disk https://www.rockauto.com/en/moreinfo...10605&jsn=1342

[BobBray]

I ordered an M-Pact 04528 from Rockauto, and it is the same as the Platinum Drivetrain 04-528 as you can see in the pictures. Member 63gmc4x4 has used the Power Torque (O'Reilly's) 70375-HD1 clutch. It has an 11" flat disc and a diaphragm spring pressure plate. The GMC V-6's all came with 3 lever Borg & Beck style pressure plates which have more clamping force than a diaphragm spring type. The 70375-HD1 is for mid-90's GM pickups. M-Pact sells an 11" 10 spline disc part #383348 that has a flat flywheel surface, I have heard that this disc works on a GMC V-6 and can be used with a 12" pressure plate, but I have not tried it myself. Note that most GMC V-6's came from the factory with 11" clutches but a 12" can be used. Next week I will call M-Pact and see what they have to say.

[BobBray]

Another view of the M-Pact 04528 disc

[Funky61]

Jerrspud added the link to 63gmc4X4’s thread of a clutch disc that would work. I sent my disc that did not fit back to Platinum Driveline and had them find me one from a 1996 Chevy truck 1500 with the 4.3 V6.

Here is that disc, #381066, which cross checked to 70375 and 04121.
I have it here compared to a NOS GMC 11” disc I bought awhile back.

The springs are more recessed in the newer disc and it sits flatter, but the cone is taller on the original by about 3/8”.

[Funky61]

A few more photos; New disc on left.

Thanks to Jerrspud for updating numbers on the throw out bearing and 63gmc4X4 for his efforts on digging further to find the disc.

[BobBray]

The cone on the transmission side shouldn't make any difference. The 381066 disc is 11", correct? I have not called M-Pact yet, I am thinking about trying an M-Pact 384195ST1, it's a 12" diameter 10 spline 1.125" disc for a 1993 Chevy/GMC 3500 that appears flat on the flywheel side. I want to see if it will work with the 3 lever 12" pressure plate that comes in the Platinum/M-Pact 04528.

https://www.rockauto.com/en/moreinfo...=10605&jsn=648

[Funky61]

Yes 11" on the disc. That link and pics on the site seem looks like it may work.

[BobBray]

I have been working on this issue, sorry for not getting back to you all sooner but I have been looking around for another solution. The problem is that the M-Pact/Rhinopac/AMS 04-528 12" clutch listed for GMC V-6 that fit fine for years now comes with a disc that will not clear the V-6 flywheel. The lever-type pressure plate, throwout bearing, and pilot bearing are all correct, it's just the disc that will not work. '63gmc4X4' did find an 11" diaphragm spring clutch that will work, part #K7037501HD1. That's one good solution, and is probably a little easier to operate as well. For those who wish to use a 12" clutch with the OEM lever-type pressure plate I found a disc that will work with the 04-528 kit. M-Pact part #384195ST1 is a high-torque steel-back disc that is 1.125" X 10 spline and is VERY flat on the flywheel side. It fits 1991-1995 GM trucks and is readily available anywhere.