06 SS/SC(mostly stock, 11-12lbs boost) removed non-LSD to replace with F35. Picked up a LSD trans from a recycler that was clearing stock for just $250. Prior (with original trans) we have replaced clutch twice, first due to wear, second due to slippage. Flywheel surfaced and complete clutch kit(disc, press and slave) each time.

When we took apart, signs of slippage again. First picture is of the first replacement after about 3-5k miles. second is of current pressure plate with about same mileage, lightly sanded to remove some of the bluing from heat. Looking for advice and DO NOT want to remove trans again!!!!

I seem to have no/few issues with clutch, son complains of complete fail of clutch on hard shifts (engines screams/no go). I have read the sticky on driving habits and I normally shift at higher RPMs, from driving MG's that only have power in the higher RPM range (4.5-6K). Son does shift lower at lower RPMs, have talked about.

I do not want to take trans back out. I haven't measured the bearing/plate clearance since there are no shims and stock parts are being used. Plus slippage seems to be too little clearance(bearing causing plate not fully releasing) rather then too wide of a gap.

Looking at replacing clutch with Exedy clutch(4 puc) from ZZP ($350) and new flywheel. Does using stage 2 clutches help with slippage? We do have the stock spacer between trans and engine, are their spacers with different thicknesses?

What have you done to avoid clutch slipping?

signed;
Tired but experienced trans remover

 

An upgraded clutch will grab better and reduce slipping under more power but first I would make sure that is actually your problem. Have you ever gone for a ride with your son? Does his foot rest on the clutch as he cruises down the road? Does he use excessive rpm and ride the clutch out longer than necessary at each stop? Are his clutch engagement times between shifts long and drawn out or quick and relatively immediate? It may be his driving habits that are burning up clutches. If not, many people like the GMPP clutch for the F35 and it should easily handle all the power of the stock application with proper driving habits.

 

The problem with the stock system is that the pressure plate is weak, but with good driving habits, it does last a long time. Honestly, if he's having this much trouble... I'm inclined to blame the driver.

If you change it again, the GMPP Upgraded Clutch kit should work fine. I would probably stop reusing the same old flywheel.

My GMPP clutch kit held around 400 ft-lbs with no issues.

Sidebar: that car came with an F35, so there was no "F23 to F35 Swap".

 

What the others have said, get the gmpp clutch and a new flywheel. You will be glad you did. I also agree with possible driver error.

 

If you had the friction surface of the flywheel machined but not the mounting surface, thats causing it to slip.

 

Had issues with finding a GMPP clutch kit in stock. Got a hold of ZZP today and they do have them, but not the flywheel.

Looks like the old clutches were Luk. So hopefully the GMPP will do fine. Not sure if flywheel was properly resurfaced so would like to replace. I have only been able to locate OEM units for $375 and up or Rockauto has AMS unit. ZZP does have the aluminum flywheel $289 but question if good for street. In the MG world aluminum is kept to the track due to the quick RPM drop on a motor that only makes power above 4500. That shouldn't be too much of an issue on newer motors but am also weary of the friction plate that wears???? Anyone with info educate me on this.

Chris also does drive our ZR2 S10 and seems fine, but the SS is a different type of driving. I did teach him on my MG but he was weary about getting into it, new to driving plus I had just dropped the V6 into it. Once the car is back together I will find a place so I can be with him when he gets into it. I have never been in the car when he lets it eat. I really never got on it from a stop so never really taxed the clutch.

keep the suggestions coming

 

Aluminum flywheels can certainly make a daily driver car a PITA to drive. They're not as bad for this car since it has good power, but they're still a bit of a hassle.

Not something that I'd do to a car that a new driver is using.

The OE supply of much needed parts for these things seems to be drying up. Not a good sign for the future. GM is already no longer offering new LSD F35 transmissions.

 

I ran several aluminum flywheels in my high hp mustangs with no issues on the street.



This is from RAM Clutches website, I like their explanation.

The flywheel is primarily an inertia device. As the flywheel spins it stores energy or inertia that helps move the mass of the vehicle as you engage the clutch.

Factory flywheels are designed to apply the optimum amount of stored energy to provide good drivability for the vehicle. Vehicles with smaller engines have relatively heavy flywheels due to the extra inertia needed for a smooth transition to engagement. Reducing the weight of the flywheel, while increasing performance, could reduce the drivability of the vehicle.

Under racing conditions, the flywheel weight can be used to control the inertia applied to the drivetrain. For instance, if a vehicle tends to ‘bog’ upon engagement of the clutch, increasing the flywheel weight will increase the inertia needed to launch the vehicle smoothly. Too much flywheel weight may cause excessive inertia to be applied, causing the tires to spin. Reducing flywheel weight under this condition will reduce the inertia applied to the vehicle and allow smoother acceleration.

Aluminum flywheels are used in drag racing high horsepower applications which require the clutch to slip as the vehicle leaves the line. Steel flywheels are used primarily in street driven vehicles.

Other load factors can effect flywheel selection, such as rear gearing or transmission gearing. With the abundance of gearing choices available today, it is possible to use almost any flywheel if the proper selection of gears is made. This was not always the case – in the 70’s when the gearing choices were not available, racers had no choice but to use the flywheel weight to control the vehicles on launch. It is more efficient to use a light flywheel and proper gearing than to use tall gearing and a heavier flywheel.

Tech Tip
Flywheels and Drivability

Selecting the proper flywheel helps you achieve the drivability you desire for your vehicle. Heavy street cars will benefit from a heavier flywheel to generate the inertia to get you moving. An aluminum flywheel will not generate as much inertia to move the vehicle, and thus it would be necessary to slip the clutch more on takeoff. Some street vehicles may benefit from a lighter flywheel, but only if there is enough rear gear to help you transition the clutch smoothly without excessive slippage.

 

I agree here, may not be the clutch and trans. It may be the driver, but I'm not here to judge. We all learned at one time, although I feel for you and know how it feels to not want to pull the trans again. I know mine is slightly different because I have the turbo Cobalt, but I have over 135k miles on the original clutch, the car was 100% stock up and owned buy and older guy until 75k, but still 55k tuned and driven hard. I have beaten on the car hard at times doing autocross a few times, a few passes on the drag strip, canyon runs when I lived in California, Tail of the Dragon runs, and a bunch of daily beating on the car.

Also, I just read that you had the flywheel machined. That could be the problem, I don't know the clearances and allowable limits but I do know GM doesn't recommend it.

As for GMPP you can check Crate Engine Depot, Tom is really helpful in GM parts we need.

CED Clutches
Clutch Kits

OTTP has OE replacement flywheels
https://www.overthetopperformance.co...eel_p_160.html

 

I've been driving stick since 1979. I ran the stock clutch in my LNF for about 40,000 miles, most of which was on an E85 tune (359whp/418wtq) and including quite a few *****-out lapping days at the road track on very sticky tires. When I replaced it with a Clutchmasters Stage 4 as part of my turbo upgrade and engine build, my mechanic commented that the old clutch plate looked "like new".
Whenever I hear about stock LSJ/LNF cars with slipping clutches, I can't help but think it has to be a driver issue, like has been said before.