This one has a little mystery behind it. Here is the background,

The clutch has about 15-18k on it. When I first installed the T-56, I noticed a little gear whine when the car was in neutral with the clutch in or out, but would stop when the car was put in gear. Don't think that was a major concern, but wanted to see if anyone else had it.

I ran into major vibration problems with the sphon T/A hitting the driveshaft loop, like several others here. I eventually beat the loop up when I had it up on a rack.

The car still had some vibes at shafts critical speed. Changing to a beat up stock AL shaft just moved the crital speed. I eventually went with the 44th gen steel one I got with the kit that had a large counter weight on the front.

Another possibility is that the bellhousing was not dialed in, and the input shaft was not parallel to the crank.

All I know is that the flywheel isn't really scorched, nor the t.o.b or p.plate.

There is one other thing. While I was away for 3 weeks in Brazil, I let my roommate borrow the bird cause his timing belt broke. Not necessarily saying that he beat on it (but it sure as hell is possible) but maybe he drove with his foot on the clutch all the time or something to generate a ****-ton of heat to weaken the metal. I've been back driving it the last 3 weeks and have not been beating on it.

So, driveline vibration, roommate, or defective product???

 

Yes I've seen that, unfortunately.

Did you replace the pilot bushing / bearing when you put it together? That's what it looks like to me.

None of the other things you mention would have anything whatsoever to do with the disk getting flexed at that point enough to fatigue it.

One other thing that can cause that is putting the thing together with the disk backwards; even if you realized that it was wrong and took it back apart and turned the disk around the right way, the act of tightening it down with it in backwards will try to punch the hub out of the disk, and bend all those wavy plates of spring steel.

 

New brass bushing was installed at time of swap. I was going to go with a roller, but the guy at summit said that if I was not dialing in the bellhousing, that the roller would get destroyed fast.

I read an article recenetly in CHP or CC that address the fast most people do not take the time to dial in the bellhousing. Some company release a bullet-proof t-56 bellhousing with adapter plates that allows several combo's, like using a LS1 trans on a non LS1 block. I'm really going to look into getting the equpiment to shim it dead on.

 

Hmm, I'm running a roller bearing in mine, have been for the past year and a half. When I pulled the motor for a rebuild it's still in great shape. I haven't "dialed in" my bellhousing either....

 

Roller bearings are stock in many, many applications, without "dialed in" bell housings. I have been running them for about a decade and a half in my 83, with just plain old stock bell housings on stock straight dowel pins.

I prefer the rollers, obviously; but in the grand scheme of things it's a pretty minor difference at most. The main thing is just to make sure you have a good (not worn-out) one installed.

 

I'm sure that most bellhousings mate perfect with the engine. Maybe mine has been warped, I did buy it used. I'm sure that rollers last as long as the angles are not too far off. I'm just going to play it safe and dial mine in. I have to try to figure out why this failed and that is a possible reason. But the salesman right away asked what I was putting the roller in and right away said avoid the roller unless you are dialing it in. Point being that they must have had problems with this otherwise it would not be an issue.

 

Well I'm just a guy that's been building motors for a few decades, I'm sure a phone salesman would know alot more about building motors than anybody like me would ever know.

Let us know how it works out, and what you find when you "dial it in". I'm sure the salesman told you what to look for, how to do it and what parts it would take to effect a change if you find that it's off.

 

Here we go again with the sarcasm. Builing motors for a few decades huh. Are you a machist or a broadcast engineer. Do you take question on ordering parts 8 hours a day. They salemans at summit is someone who I've been dealing with since I started ordering parts for my ride back in the early 90's. So please end with the bs, cause it make me wanna slap someone.

 

RB knows what he's talking about, he's been a member here for a long time and has given lots of good advice. FWIW I would take his advice over some salesman's any day....

 

Feel free to ignore my advice or even go slap someone, as you please. It won't fix your clutch. I personally wouldn't trust a salesman for technical advice myself, especially not when he gives "advice" that makes it sound like you're talking about something exotic and dangerous when in fact you're talking about a stock part.

Incidentally, I've never owned anything but used bell housings.

And did he tell you what he means by "dialing in" a bell housing?

 

I'm not ignoring advice, I'm blasting your sarcasm which maybe you do not like in return....... whatever...

Dialing in the bh is using shims if necessary to ensure that the input shaft lines up perfectly with the crank/ pilot bushing. I know that there is not much difference between the back of an LT1 and my 305, but maybe it is possible that the bellhousing is not mating up correctly. You use a dial indicator to make sure that the measurement in within a set tolerance. I'll have to dig out the article. When I do, I'll scan it in. Again, the article empahsizes the lack of attention most people have for this tolerance.

The overall point is this. If that tolerance is off, you will waste a roller pilot bushing faster than a brass. In either case, the variance can cause harmonic, which caused heat, which may be a reason that this has failed. To say that vibration could not have caused fatigue is erroneous. It is not like this thing failed a week after I have put it in. I have ran this car twice cross country to Chicago and and back, once driving about 2k miles straight.

I'll have to check the bushing once I pull it out.

 

roller bearing, eh?

Go to you GM dealership and ask for a pilot bushing/bearing for a 1989 Camaro Vin F (LB9 305 TPI) with a manual trans (yes they can be that stupid to ask that). The part he gives you is a roller pilot bearing.

 

Yes, in fact some of the ones I have used over the years have come from the Chevrolet dealer. They even cost about the same there as they do from Moroso et al.... about $14 IIRC. A bit pricier than a 75¢ bronze bushing unfortunately. I used to keep a box of the bronze ones in stock in my garage (from Dorman) but I ran out, so nowadays I just buy the bearings instead.

I hate to take the risk of being accused of being sarcastic about a magazine article, but I'm going to let some reality and real-world experience interfere anyway...

The measurement of a BH's fit to an engine that's actually the most important, and also the most likely to be out of tolerance, is actually something besides what can be corrected with shims. It's whether the clutch gear bearing retainer hole is centered on the center of the crank. Normal block machining tolerances are surprisingly large in that area. And once a block has been align-bored, the problem can get so bad that a trans can't survive. The cure is offset dowel pins, to move the BH (and trans) around on the rear of the motor. I've never had to shim one, but I have had to use offset dowels; and in fact one of my cars (74 Caprice 454 convertible) needs them but doesn't have them, and makes the front pump whine loudly and generally eats Turbo 400s as a result.

 

Do not shim the belhousing on your T-56! You DO need a roller pilot bearing installed in center hole of the back of your crank. Make sure the bearing is flush with the crank surface when installed. The tip of the input shaft on the tranny fits snug in the center of the pilot bearing. Also make sure you grease the inside of the bearing. I've been running my T-56 in my car for a couple years now with the stock motor and with the new motor. The purpose of the bearing is to keep in input shaft inline and to keep it from moving/vibrating. The input moving/vibrating will cause pre-mature clutch failure.

The factory does not shim the bellhousing, they use a roller pilot bearing or a bronze bushing (the bearing is better). They do that for the reason listed above.

Hope that helps!

 

Ok I found the article, two of them actually. Here is what came out of CHP 7-03 pg 30 in regards to McLeods new modular bellhousing that claims to fit any manaul (except the ZF-6) in a variety of Ford, Mopars, Buicks and Chevys.

"Any good good manual trans expert will tell you that the one job of a bh is to perfectly align the centerline of the trans input shaft with the centerline of the crankshaft. If both are within 0.005 to 0.010", you are good to go. ..... To dial in an older style, you offset the bh with dowel pins....."

Pretty much what you just said, RB. I new they offset it, I was just guessed saying shims until I could find the article.

CHP 9-03 has an article on how to dial it in. They attach a mag-base on a dial ind. to the crank with the flywheel (and scattershlied) installed. Setting the dial to 0 at 12 o'clock, they rotate the crank and take measurements at 3,6 & 9. They mesured 0.030 at 6, 0.015 at 3 & 9. Thus it needed to come up 0.015 (1/2 of the 6 o'clock reading)

The pb that came with the McCLeod kit and the one they installed where both brass. I'm sending an e-mail to McLeod to ask them about rollers.

As far as my pb, i just crawled under to take a look. There was alot of rust colored dust around it. As I cleaned it out, the bottom layer was caked on and black. It was recessed into the crank about 0.010 and the edges are sharp at a couple points.

 

Yeah, pulled out a twin disc clutch from a T56 yesterday and it was worse than that. I pulled the tranny out and handfulls of clutch material and metal chunks fell out. There were a few holes in the bellhousing too . Turns out that the guy that put it in didn't have it aligned right so he messed up the pilot bearing while trying to spline the tranny

 

Yea Ive seen clutches like that some were installed backwards, I cant see how the pressure plate would even mount flush but thats the way they came out. Some were destroyed from shock (racing) and some from to much load (hauling).

As far as the roller bearing debate here. RB is right you dont need a "dialed in" bell housing to use one thats just plain BS. The bellhousing sits is dowels and the once its in theres not movement that would frag a pilot bearing. IF that were true a pilot bushing would wear down to nothing in months.

Now for the phone rep/car guru you talked to. The person may know somthing about cars and the part there selling but you need to consider the simple fact that if they knew so damn much they sure as heck wouldent be answering the phone for minimum wage would they? I dont know one parts monkey that makes more then a mechanic do you?

Funny too because back in high school years ago a friend (not a car guy either) had a job at the local telemarket place on inbound calls. He told me he took PART orders for all the magazines, camshafts, carbs, intakes you name it.

 

I opt for the bushing when I have a choice as, being a one piece unit, they are less likely to explode/come apart. I've heard horror stories about exploding roller bearings but never a bushing...

Assuming that the roller bearing stays in one piece, there is little difference...

I didn't dial in my T56. I also employed a used bellhousing and it seems to work as designed and intended .

My $.02

 

I've seen damage like that from severe wheel hop. The rapid unloading and loading is more than the disc can take.

 

summit sales people are idiots

 

Looks to me like fatique stress from drag racing has sheared the drive plate. Have seen this before.... nothing to do with roller bearings or bell housing alignment IMHO. Factory specs more than consistant enough.

Edit: I notice you Drag Race the car. I'd put it down to normal fatique from the drag racing.... Could be any of the following:

1) Defective part.

2) Normal fatique caused from Drag Racing. Good bite with not much HP means you're probably launching at a fairly high RPM. Bet you don't get a lot of wheelspin. This places a lot of load on the clutch.

3) Your buddy beat the snought out of the car

Option #3 could cost you a good friend...so be carefull. Definately could be metal fatique from strip use.

Edit: I've never been impressed with Centerforce clutches. Neither has my engine builder. The diaphrams and discs are supplied by LUK. Nothing special there. Centerforce then adds their patented weight system. That's it. OK quality, but not great.

The Dual Friction series is better in quality, disc not supplied by LUK. I would consider a Mcleod clutch over a Centerforce any day.

 

Just a thought on your vibration problem. Have you properly phased the drivesahft angle? This is critical, especially when running an adjustable torque arm which can change the driveshaft angle all over the place.

Proper procedure is to place car on a ramp hoist, with suspension loaded. With a magnetic angle finder, measure the angle of the driveshaft coming out of the tranny. Measure the Tranny U\joint yoke. Let's say it's 1.5deg down. Now measure the angle of the yoke on the diff end. This should be the INVERSE of the tranny measurement. In this case it would be 1.5deg up.

Spohn has detailed procedures to follow with their T\A instructions. Here's the problem. The correct settings for driveshaft angle, to decrease vibration problems, may not be the best soultion to get the bite that you need to launch the car. In that case you may have to shim the tranny mounting location(s) to match the angle at the pinion yoke. Big angles can also cause vibration problems.

 

I keep the angle at 0, -1 if I decide to take the time to adjust it before I go to the track. At least close to that since the angle finder is really scaled tight. I'm planning on picking up a digital on soon to have better accuracy.

I also drive the car 90% on the freeways. I tend to keep the car at 2000 - 2500 in overdrive = 4000 - 5000 rpm shaft speed. Before the trans goes in again, I'm getting a new driveshaft. There are several post that detail the poor quality of any stock shaft other than the 3" AL on the 4th gens.

I'm trying to find the reciept from the clutch. I saw that I put on my profile that it was a centerforce. It may be a ram. The name stamped on the clutch however is VALEO????

Even thought the car is underpowered, the suspension did hook hard on launch. Hardley ever spun the tires.

I'm sure that it is a combination of all of the above. Like anything else, I'll just take it as a learning experience and do everything possible to not let it happen again.

Thanks!

 

ive seen that where all that was left was the hub, no more friction ring.....in a 7000 series GMC, blew the cover right off, there was nothing left of it

 

. i couldnt agree with u more on that. ive had two dual frictions and ive hated them. smoked two of their clutches in a year, im goin with a spec soon.

 

thats interesting, im putting 410hp (around 500 at the flywheel)to the tires, ive had the same dual friction in the car for 2 seasons now,

it has about 60 passes on it, all launched on slicks over 4500rpm, with 1.68-1.78 short times.....its never slipped, or smoked or made a peep.

centerforce clutches usually fail because people dont break them in gently they way they are supposed to, and ive never seen a centerforce break like that unless something crazy happened, they usually just burn up the disc if they do fail

 

When I got my clutch, I asked the guy that I got my trans from if I needed to break it in. He said, pretty much since it is a HP clutch that you would not have to. I still took it easy for the first couple hundred miles.

Any other special tips on breaking in a clutch other that avoiding 4500 rpm launches.

Someone heard my prayers, I picked up a used carbonfiber shaft yesterday for 350 My instinct was telling me to hold on to my cash and not rush out and buy a clutch, then I saw the ad in the paper and made sure I got it the same day.

 

Late reply on this topic, but something worth mentioning to people buying a used manual trans.

Turns out that the input shaft was bent. This was more than likely the culprit for the vibration, although I still get some around 3000. I have a steetdampier, just have not had the time to install it.

PS. RB, sorry for the rudeness. Looking back on this a few years later, I'm a bit embarrassed. Must have just been emotional over the car being torn apart again.

 

Just to add a little on top...

Your input shaft being bent makes great sense. You know that noise you heard when the clutch was in or out? That was your input shaft spinning (or attempting to) because it was "stuck" to your crankshaft via the pilot bushing. I have had those stupid bushings come the wrong size and the first time I just massaged it a little to get the input shaft to go in.

Bad idea.

The input shaft spun regardless of clutch engagement. It didn't stop until I held the brakes while cranking the engine and the home made lathe action turned out some excess material on the bushing. Then it was okay. What a PIA.

I have never had that problem with the bearing. If you get the bearing for the 6.2 diesel chevy truck (circa 1988) with 4 speed the rollers are actually a little tougher than the factory Firebird ones.

Just a thought!