clutch failure x3?

[otisd85]

okay fellas, i did my first clutch in my dads 1975 chevy shortbox 4x4 when i was 14, im 25 now that clutch still works great and i have 4 other chevys i have replaced the auto trans with sm-465's, and helped 2 friends do the same thing. thats 7 total before this truck, all of them have been gas burners, a 454, a 402, and the rest a variety of sbc's.

i seem to be having difficulty with the one between my 6.2 and nv4500, the clutch i use is a MU1909-1C, its just a NAPA clutch. the base number is the MU1909-1, the C at the end is the ceramic version. like i said ive put this in 7 trucks now, and the only problem ive ever had was when i installed the throwout bearing wrong on the fork(my bad), other than that they have all worked flawlessly, until now.

the truck im working on is the one in my sig and my avitar, and is the 8th truck ive put this clutch in but my first 6.2 and my first nv4500. the first clutch i put in this truck gave out after about a year, #2 and 3 lasted about 4 months each. all 3 failures have been due to the springs in the center of the clutch disc breaking apart, falling out and wedging between the disc and flywheel or disk and pressure plate. there is no slippage when this happens its just that the clutch wont dissenguage. i havent tried any other brands of clutch because this has been warrantied but i dont really want to keep doing this over and over so im looking for different options or some thing im overlooking.

i know some of the later 6.5TDs had dual mass flywheels but i dont know what that does for you, or what difference it makes if any, or if it even has any relevance to this at all

i dont know what else to try or where to even start but i want to do something different this time and hopefully remedy the situation.

thank you

 

[south bend clutch]

The problem that you are having is the clutch disc is designed for a gas motor. The clutch disc for the diesel needs to be what is called a two stage hub to protect the diesel pulses from the clutch springs. The center of the disc actually floats and has a non-resistant rotation to the hub. With the gas design, this feature is not there and you are literally shaking the clutch springs to pieces.

Peter

 

[otisd85]

okay Peter, ive been looking around for more info on my clutch problem and seen a lot of stuff you have chimed in about on idi ford clutches. so i have some more questions.

first is my pilot bushing is a bit wolered out and input shaft has some play but not what i would consider excessive, could this contribute to my problem?

second when i look up a clutch for a 1980's chevy, that would have a 6.2/sm465 it comes up with one part number, but when i look up a clutch for a 90's truck with a 6.5 with a standard flywheel and a nv4500 it comes up with different numbers all together. but they seem to have the same part description, ie "Disc Size: 12"-10-1 1/8";w/ Raised Diaphragm Cover;w/ Solid Flywheel".
now i dont expect you to know everything about your competitors products, but as far as the south bend lineup goes is there a difference in your clutch kits from the 80's-90's with a solid flywheel. and if they both come up with a 12' disk with a 10 spline 1-1/8' diameter hole what is the difference in them?

the combination of parts i have is a 1990 6.2, with a solid flywheel that was between a 86 6.2 and a sm465, and a 1992 nv4500 that was behind a tbi350. so with that info can you give me a educated guess on what clutch you would recommend, and if you even think its necessary for an upgraded clutch or if a stocker would suffice?

it is turboed but still a 6.2, i would be surprised if was pushin 200hp but i would guess its in that range.

 

[south bend clutch]

Any wear with the pilot bushing or front bearing will accelerate the problem with the springs in the clutch disc. I am not worried about competitors or trying to sell a clutch but this is a common problem we see with the part store clutches. Heck, even in our books they call for the same clutch as you stated but the fact of the matter is we know different through our 60 years of experience. The 6.5 clutch does have the same dimensions ie 11 7/8" OD X 1 1/8" 10 spline but from 92-95 the system supported a dual mass flywheel to absorb the diesel pulses. This is a very expensive setup and LUK made a solid flywheel option that uses a series dampened clutch disc to do away with the DMF as you can see in the first two pictures here... http://www.southbendclutch.com/chevy_catalog.html

Back to the 6.2, if you use a disc designed for a diesel, it will protect the springs from the pulses of the crank do to the diesel engine. On a gas engine the crank spins without hesitation. With a diesel it oscillates with every pulse of the injectors. So with your case it pulses 8 times per revolution. With a standard gas designed disc it will literally shake it apart.

Hope this helps...

Peter

 

[u2slow]

I have smashed apart a stock 6.2L clutch also. The springs stayed intact, but the center hub broke free and started slipping inside the disc.

http://picasaweb.google.com/lh/photo/61Cxf-vXchww-xyKnDE6LA?feat=directlink

Before I lost the truck, I had found a 96-97 (I think) 6.5TD single-mass flywheel and clutch. This has two different rings of damper springs. Looks just like SBC's kit. Never got it in the truck to try it though.

 

[otisd85]

yeah thats what i think im looking into is a clutch for a 6.5 with a single mass flywheel i considered the sbc but i dont think my truck is putting out enough power to need it so a stocker will probably be fine but im out of town working now so thats what im going to try when i get home unless i find a reason to try somthing different before then

 

[dyoung14]

I have smashed apart a stock 6.2L clutch also. The springs stayed intact, but the center hub broke free and started slipping inside the disc.

http://picasaweb.google.com/lh/photo/61Cxf-vXchww-xyKnDE6LA?feat=directlink

Before I lost the truck, I had found a 96-97 (I think) 6.5TD single-mass flywheel and clutch. This has two different rings of damper springs. Looks just like SBC's kit. Never got it in the truck to try it though.

I busted the entire hub out of the one on my idi, then i swapped in one from autozone, and it slips if i really get on it hard sometimes and its only couple months old

 

[otisd85]

you say "it slips if i really get on it hard sometimes", and if this is the truck in your sig, than that would not surprise me. my 6.2 isnt a real power house, so i think im going to go with another napa clutch (but one for a diesel this time) and hopefully keep this truck on the road at least until i find a donor cummins i can afford to swap in it

 

[dyoung14]

you say "it slips if i really get on it hard sometimes", and if this is the truck in your sig, than that would not surprise me. my 6.2 isnt a real power house, so i think im going to go with another napa clutch (but one for a diesel this time) and hopefully keep this truck on the road at least until i find a donor cummins i can afford to swap in it

Yea a stock diesel clutch should hold up just fine for you, your not going crazy with that engine so it should be ok, i know the stock replacement valeo was fine for mine when i was non turbo, but when i threw a turbo on and starting going crazy with boost it didnt like it at all, now i have blown a head gasket

 

[u2slow]

Yea a stock diesel clutch should hold up just fine for you, your not going crazy with that engine so it should be ok, i know the stock replacement valeo was fine for mine when i was non turbo, but when i threw a turbo on and starting going crazy with boost it didnt like it at all, now i have blown a head gasket

My 6.2L NA was tired and LOOSE... 370,000km or something when I put the 4spd in. It was a Sach's branded Borg & Beck replacement for an 84-87 J-code engine with hydraulic clutch. The disc lasted about 6000km. This was a 2wd Suburban with a 3.21 axle.

That's what got me onto the path of finding a disc with a different damper hub design.

 

[otisd85]

well i know its been awhile, from the dates on this thread it looks like the diesel clutch lasted about 18 months. sense i last posted on this thread, i replaced the clutch in my dads 1996 chevy with a 6.5 and his is still working perfect. mine on the other hand gave up on me again, same problem as before, clutch will not disengage. i dont have it apart yet, but i am assuming its the springs again, it is acting exactly as it did with the previous failures.

im kind of at a loss here, i need to fix it again, but i would like to figure out the problem so i can get a better end result.

any advice would be much appreciated, thanks in advance.

 

[chvycmnslvr68]

did you ever replace your pilot bearing .. the only other thing that i can think of is that your "Off center" causing the disc to have side pressure on it ... how much would you be willing to give for a cummins .. I have one in my sig pic and have a newer one that i want to put in ... this one is from a 93 and dont use any oil but has some inj. pump issues that i am in the process of correcting ...

 

[chvycmnslvr68]

By the way ... I like your truck ... I plan on taking the duals off mine and lifting it about 4" so i can put on some 18 or twenty inch wheels

 

[otisd85]

i replace the pilot every time with a new oil impregnated brass bushing, and it seems to be wallerd out every time. what might cause it to be off centered? there are 2 dowels in the back of the block that fit nice and snug in the trans bellhousing. the mating surfaces between the block and bell are clean and smooth. what else could make it off centered?

i have 2 cummins now, one complete donor 95 dodge auto 4x4, and a 190 horse out of a 96 school bus, but now i think instead of doing a cummins swap in this truck, im going to do a full off frame restoration on another truck, with a cummins of course. when thats done ill drop a cummins in this truck, that way im not without a truck during the swap, i can take my time, buy parts as money permits, and good deals come along. (now im just without a truck during the multiple clutch replacements, and this time probably a trans rebuild)

chvycmnslvr68 its too bad your so far away, i would be interested in your dually bed, and your front end. i think i seen your build thread awhile back, looks sweet. i like the way big rims look, ive just never been a fan of the price of the rims, and then how much more expensive it makes the tires.

 

[otisd85]

chvycmnslvr68, if your truck has the drw spacers that bolt on the front rotors, and you are willing to get rid of them, i would be interested in them if the price was right and shipping isnt too outrageous to 68061.


anyone else notice sigs quit showing up?