Clutch Question...And poll I guess

[ShoStyle]

I have searched the forum and have not found a definitive answer. So I am going to ask.

I have smashed my second pressure plate in my 91+. I do not do burnouts, or drive crazy hard, but I have snapped the bands on my pressure plate for the second time in about a week after install.

The pressure plate bands (two out of three) are twisted off both plates. Identical damage on both.

My car has a SHOshop stage 4 kit, ceramic TOB and a fidanza flywheel and is running well.

Here is my questions.

WHY is this happening to me?!?!??

And I kinda think I need an upgraded clutch kit/Pressure plate with more clamping force so which kit works best in our cars?

I narrowed my three choices to Clutchnet, Clutchmasters, or South Bend.

Which is the best?

Thanks in advance

 

[Phoenix]

I dont think I have seen a clutchmasters with broken straps yet , its imperative you buy a ceramic TOB with your new kit.

 

[kikkinasphalt]

im going with

Clutchmasters PP
Clutchnet Disc
Ceramic TOB


and im ditching the fidenza.

 

[LOUDSHO92]

My ClutchMasters Stage 1 has done quite well.

SouthBend clutches have done quite well.

 

[gmorrell]

I used to build SHO clutches, damn near indestructible SHO clutches, it would help to see pictures of the strap failures. Can you post or link some pictures?

Are the strap rivets de-heading, or are the straps buckling?

Shock loading from aggressive friction materials is what kills the drive strap rivets. What are the clutch disc lining materials? Flywheel and pressure plate side?

Aggressive downshifting without good rev matching puts the drive straps in compression, they weren't designed for this loading and it spreads the straps, which is also ******* the rivet heads.

Please define "SHOshop stage 4 kit".

 

[38SHO]

I have a clutch net pressure plate with extra straps
I have a clutch net clutch disc
I have a sho shop/sho source 8lb aluminum flywheel
I have a shonut ceramic TOB

I am in love with the clutch net clutch disc. This thing is beefy, its a new design, that shares nothing with an oem disc. I like how it has different springs, the springs are enclosed better, I didn't say the unit was lighter, but I'll take the added durability instead of less weight here. I will probably always retain this clutch disc and just have someone bond new friction material to it when the time comes........

i'm going to think that with the aluminum lighter flywheels, it puts more strain on the pressure plate when changing gears or launching. I broke my pressure plate strap after installing my flywheel. I whent to a clutchnet one with more straps, and it has held together beautifully.......

what kind of pressure plate straps have you ruined? is it a stock setup?

even if that were the case, I would think that ruining two pressure plates within a week, in the manner you described, both with exactly the same wierd damage... that something could be going on here.... I would research around some more before buying expensive parts that just might break in a week as well....

do you ever feel anything wierd with your pedal? have you driven other SHO's to have a comparison as to how the clutch works in them.

I would listen to Gary Morrell and answer his questions to see what he thinks about it.......

I'm good at changing clutch parts, but I'm not an engineer!

 

[AREA 91]

Do NOT run a double diaphram pressure plate with an aluminum flywheel! You will have shifting problems like I discovered.


My Green 91+ combo:
Billet 17LB flywheel
Clutch Master's Stage III
Ceramic TOB
Teflon TOB Fork Bushings


I have ran a Fidanza aluminum flywheel coupled to a CM I and loved the combo.

 

[ShoStyle]

I used to build SHO clutches, damn near indestructible SHO clutches, it would help to see pictures of the strap failures. Can you post or link some pictures?

Are the strap rivets de-heading, or are the straps buckling?

Shock loading from aggressive friction materials is what kills the drive strap rivets. What are the clutch disc lining materials? Flywheel and pressure plate side?

Aggressive downshifting without good rev matching puts the drive straps in compression, they weren't designed for this loading and it spreads the straps, which is also ******* the rivet heads.

Please define "SHOshop stage 4 kit".

The bands look as if they have brake right at the rivet to the cover itself. They look as if they were compressed. Really gnarly.

SHOshop stage lV kit, as described in the SHOshop catalog. My plus has every bolt on, top end, UDP's, cams, Lpm, and exhaust available just short of Nitro and SC. All SHOshop supplied. Save for the Y-pipe which I lost in the divorce. Now it's a magnaflow. But a SHOshop Catback.

Car is smooth and powerful, eats a stock clutch in about two days, probably due more to the way I drive it, but my stock SHO with stock clutch handles m driving just fine. As does the SHO wagon which is heavier, I drive them the same way. I'm sure it's the extra torque of this engine.

 

[jedhead]

My SHO is setup about the same and I use a CM stage 1.

The CM is on the left and the stock PP is on the right. The CM has larger straps and larger rivets.



Bob

 

[93rev2sev]

It's not the extra torque of your engine. There is something else wrong. Unless you have power adders (No2, turbo, SC), a stock clutch should last a while.

 

[ShoStyle]

It's not the extra torque of your engine. There is something else wrong. Unless you have power adders (No2, turbo, SC), a stock clutch should last a while.

I checked everything that could be checked, everything is in spec, I changed transmissions, flywheels, TOB's, and clutch friction disc the second time around with the same results. Then I came across this little gem while researching the cause


http://www.shotimes.com/SHO4clutch.html

Quote from the article

Increase the strength of the torque straps and rivets, this is where most of us with high HP cars are tearing things up. The torque straps are what transmit engine torque from the pressure plate to the clutch cover, they allow the pressure plate to move in and out to engage/disengage the clutch, and they locate and center the pressure plate within the cover. High RPM shifts can de-head the soft steel rivets that secure the straps or pull the rivets right out of the pressure plate iron. Aggressive friction materials also create problems because they drastically increase the shock loads on the straps and rivets. Huge straps are not the answer either because the strap stiffness and spring constant must be properly matched to the diaphram strength and pressure plate mass, otherwise the clutch could chatter on engagement or the straps would fight the diaphram, reducing the clamp load. Steve Hazard's fabricator has changed to a very strong, stainless steel rivet, which seems to have fixed the rivet strength problem.

 

[expy916]

A stock clutch should be fine, I have a stock clutch in mine and I have really beat the crap out of the clutch and its been over a year since it was installed.

 

[AREA 91]

My SHO is setup about the same and I use a CM stage 1.

The CM is on the left and the stock PP is on the right. The CM has larger straps and larger rivets.



Bob

STOCK on the left CM on the right!!!!

 

[ShoStyle]

A stock clutch should be fine, I have a stock clutch in mine and I have really beat the crap out of the clutch and its been over a year since it was installed.

It's Not the clutch, It's the pressure plate is not holding to the abuse. I smashed two of them. But I'm putting a heavy duty pressure plate in so that should fix that issue.

I'm just a little too ******* them I'm guessing. But I'll know by next week if the problem is sorted.

 

[expy916]

It's Not the clutch, It's the pressure plate is not holding to the abuse. I smashed two of them. But I'm putting a heavy duty pressure plate in so that should fix that issue.

I'm just a little too ******* them I'm guessing. But I'll know by next week if the problem is sorted.

I didnt mean just the clutch, I meant everything. I really have beat the living crap out of it.

 

[AREA 91]

It's Not the clutch, It's the pressure plate is not holding to the abuse. I smashed two of them. But I'm putting a heavy duty pressure plate in so that should fix that issue.

I'm just a little too ******* them I'm guessing. But I'll know by next week if the problem is sorted.

It's time for a CMI pressure plate with heavy duty straps and rivits.

You also need to change your driving habits.

 

[AREA 91]

It's time for a CMI pressure plate with heavy duty straps and rivits.

You also need to change your driving habits.

Actually, I would recomend the SHO NUT HDPP.

 

[yamahaSHO]

I am also curious as to what clutch you have as from what I remember, SHO Shop had a "Hi-Revs" and "Hi-Revs Jr." clutch kit (CM3 & CM1, respectively).

 

[ShoStyle]

I was running stock clutches. Now I have a South bend Tz Stage ll with a Fidanza or SHOshop flywheel....Jury still ouit on which as of yet....

 

[ShoStyle]

Well next week turned into a year, I finally got my pressure plate out, and am busy putting in my new clutch setup. I took some pics of the pressure plate and bands, this one did better than the other pressure plates, only one band smashed. (The others had two) But I babied this one, I did break it on a trip up the coast.

I am assured that the DXD pressure plate will suffice, but man, what a PITA this has been, so I am posting this to hopefully help the next guy with this issue.

I can only attribut it to a High horsepower engine and my driving habits.

Here is the pics: