my new clutch slips!

[tubman]

"Hoop", I do remember that when I measured the height of the fingers from the surface of the flywheel on the new clutch in my car, it varied by as much as .060" (that may not sound like much, but it's damn near 1/16"). I spent a bunch of time shimming the fingers so they all came out within .007 of each other. Granted, that was on my '51, but it's about the same as the earlier cars, except for the size of the hub on the pressure plate.

I gotta believe it's something like that.

[swanwaco32]

I tried a 9" from Ft Wayne and it slipped as soon as I went into 2nd gear. It was on a 59A with merc crank. Had to go to a 10" and works great. Need to check clearance of
flywheel bolts to the springs on the clutch disc. I have taken the clutch apart after barely worn and they were hitting the bolt heads. Went to ARP Bolts with a lower head.

[cas3]

well thats interesting. if i have to change anything i will go to a 10" as my tired old knees would not like stiffer springs on the 9"

[John R]

Who here knows of a good GM style 10.5" clutch manufacturer that is KNOWN to correctly work with our big, fat and flat throw-out bearings???[/QUOTE]


This is the $64 question. I'm patiently waiting and hoping to see a response.
John

[JSeery]

Originally Posted by cas3

well thats interesting. if i have to change anything i will go to a 10" as my tired old knees would not like stiffer springs on the 9"

Keep in mind that the 10 inch pressure plate spring pressure is greater than the 9 inch pressure plates. Sometimes to stiffen up the 9 inch plates 10 inch springs are used.

[cas3]

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good info Jerry, thanks for that

[David J]

Never looked into it but a slightly longer throwout arm would make a big difference on pedal pressure .

Originally Posted by cas3

well thats interesting. if i have to change anything i will go to a 10" as my tired old knees would not like stiffer springs on the 9"

[big deuce]

cas3, how did the pressure plate saga turn out?? If you went to a 10" pressure plate, you would have an extra 3 springs that are stiffer tham that of the 9" design. Probable not good on your knee. But, 6 springs from a 10" pp swapped into your 9" wouldn't be as much force to activate, but stronger that what the 9" already has?

[cas3]

Deuce, I've not done anything about it. Only slips at low RPM if you floor it, quite usable as is. I intend to someday pull it apart, check spring tension and replace with something slightly stiffer. I'm guessing one phone call to "the clutch doctor" in minnesota would tell me what spring to use, and I hope to redo it myself. Never had a PP apart before, but its just parts and bolts aint It?

[big deuce]

Load it up in a bearing press, compress the springs with a 1" square steel bar across the top. Remove the 3 bolts, and release the pressure, wah-lay. It's safely apart. Remember to stamp the orintation of how it came apart, and it needs to go back together the same way.

[solidaxle]

cas3,


I'm running a 9 inch clutch with a warmed up 8ba without any problems or slippage. Is it possible you have some contaminants on the surfaces?

[cas3]

Possible, but not likely. Everything was new and clean. You're not the first I heard of with no problems, but others say it may not work. Even the old Rumbleseat data he says to use bigger springs. It could be the lightened flywheel wants to rev up so quick. Just cutting the big blob off the 9" Ford flywheel makes a big difference...I like it.

We'll know when I someday take it apart and measure the springs.

[solidaxle]

I'm always careful not to over grease my throw-out bearing. I also lightened and balanced my flywheel, so I don't think that's your problem.

[aussie merc]

well im assuming that you cut the flywheel and pressure plate if you didnt replace it and you didnt over lube the input shaft [ive seen it done and they tried to claim warranty] so being under clutched is most likely cause unfortunately only one way to fix thats remove and replace or rebuild to bigger spec [heavier springs] this is actualy a common problem in transport where generic 15x2 clutches are common and one size dosent fit all

[oldbugger]

I have a merc 276 in my 35 with the original merc flywheel and 10 in disc, couldn't be better.

[solidaxle]

aussie,


Did you mean balance the flywheel and pressure plate?

[aussie merc]

no cutting is deglazing/ balancing is totally different a new clutch plate wont grip into a polished surface [worn] its even as simple as a quick rub by hand with some 80 grit emery tape just get rid of that shine on the surface and then chamfer the square edge off the disc inner and outer edges [ yeh rough but works for all you purist's]