Hi all

I want to look into replacing my clutch in a Muncie 4 speed, I am in the process of trying to ID if it's an M20 or M21, right now it's limited to crawling under the car and trying to get numbers. my question is , What should I replace along with the clutch at the same time, keep in mind I have never replaced a clutch or worked on a manual tranny before.I would like to replace the clutch with something rock solid that will hold up to my unfamiliarity with how to properly run with a 4 speed ( I've spent 30 years driving an automatic). I have no problem using a clutch and can shift with no problem but trying to play around with burnouts and fast shifting under load I'm sure I'm burning a little clutch by not letting off the clutch properly ( the smell is my indicator). I would like to know if there is a brand of clutch that will stand up to my skill level ( or lack of)
and lock in solid when I shift. Also as a side note if anyone would like to chip in a little tutoral on proper shifting method for burnouts and accelerating up through the gears. i try to do burnouts and sometimes the engine just rev's up with no burnout and I smell clutch, other times i must be sorta hitting the timing better and i finally break the wheels loose and it goes until I let off ( Big Block 396). I must not be letting off the clutch quick enough but I suspect the cluch is weak also. I did not know if there are certain brands of clutch and associated components that will not slip as much and be more of a lock right in type off clutch.

Thanks
Ray

A Perfection/ZOOM stock replacement clutch works fine in most mild to medium applications unless you are trying to spin a 3.31 with L-60's.

First, I would find out if you have a close ratio or a wide ratio tranny AND next find out what rearend gear ratio you have.. (Even if you have to pop the cover AND look!!).... Probably need to change lube anyway, imho...

Close ratio trannies were generally ran with 3.73 and lower r.e.g.'s whereas the wide ratio was generally ran with the 3.55's and higher due to the 2.54 first gear vs the 2.20 of the close ratio.

I love my 3.31's and my wide ratio M-20 tranny but a 26.5" tall, wide L-60 tire does strain my 11" clutch..

They measured a modern 298/53-14 on 9" rims..

Hope this is of help..

pdq67

Ditto paul's suggestion on the Zoom setup, it will work fine, and hold up for a long time.

The actual changing of it ain't too bad, other than that it's heavy. The last time, I rolled that mutha onto my chese and pressed it up there by myself, hope i never ever hafta do that again!

You'll want to remove the flywheel and have it surfaced (any machine shop can do that) be sure to replace the flywheel bolts (with bolts meant for that purpose, not hardware store stuff, ARP or GM FLYWHELL bolts!) The stick on a new disk (spring sode out) and pressure plate (use the alignment tool that comes with the zoom clutch kit) slide on a new throwout bearing, than all you gotta do is get that heavy mutha back in there.

Replace the linkage bushings and adjust the shifter right while it's out. There is room to get the trans in and out with the shifter on, just unbolt the stick.

Fwiw, I made two tranny guide bolts by grinding the heads off a couple of either main or head bolts from I forget what motor to use to help hold the tranny up in there while I lined it to get the input shaft through the clutch disc splines!!

Just install them hand tight on one side one above the other to help out...

AND I have gotten just old enough I can't press onna the mothers up in there now by myself!! H-ll to get old!!

Not happy at all..

pdq67

Ditto what PDQ said about the bolts. I went with a Centerforce dual friction. Easy effort, good clamping. I've had it for 2 years. I had a Zoom setup in my 340 Duster and still had to replace it every 12-15 months :)

I know my gear ratio is 3.31, my rear tires are BF Goodrich P245/60R15. I've been trying to ID Tranny, I can make out a P9R something on the side, and other numbers like 3925660 and 3857584GM. With the above ratio and tire size would the Zoom setup still be good or does that change the choice?


Thanks
Ray

I got 5 years out of my zoom setup, no problem. This winter I replaced the disk (Hays) and the throwout bearing and surfaced the flywheel, and it's good to go for another 5.

Everyone has their opinion, but I wouldn't trade a Centerforce for any other brand. I drag raced and street raced for years and went thru many Zoom, Hayes, etc. You could see the cowl flex depressing the clutch with these heavy units. To me the Centerforce is the best setup on the market for this application. They have sets for different uses and you don't wear out your left leg at the redlight.

If the gear spread is the same between all three shifts it's an M21. If the 3rd to 4th shift feels wider than the 1st 2nd and2nd 3rd than it's an M20. with 3.31s an M21 would be sort of a problem starting out especially starting out up a hill.

Has anyone tried the new Mcleod clutch that puts a 12" unit where the stock 11" unit went? Or one of the dual disk units?

I think some of our parts will mount the stock, 12" truck stuff but I don't know all that much about doing it or what parts have to be used together??

pdq67

Ray: I have a Center Force 10.4" clutch behind my 450 hp small block and it works like a dream. I installed it for the extra clamping pressure and so my wife could drive the car as well without cramps in her left leg. Make sure you get the rpms up high enough before you release the clutch to break the tires loose or chances are the clutch will take a beating regardless of the brand. Depending on the drivetrain combination, racers normally bring the revs up to at least 2500/3000 before they hit the "go pedal" and release the clutch. Power shifting (gas to the floor, banging the gears) takes a bit of practice. Take it easy at first, because a missed shift and an overspeed can be an expensive lesson. It's always better to smell rubber than clutch, and easier to change tires than a clutch.