Clutch Replacement Issues

[Hammer]

I've finished replacement of the clutch on #473 and just thought I would share the issues and results I learned from this. It's more for those that may not know the little differences or parts needed to complete the job when piecing together the parts as I did.

I had a weird noise coming from the clutch area and decided to replace the clutch as well as the flywheel as I am driving the car to BG in May and didn't want a problem to rear it's ugly head on the way.

I got a Valeo clutch kit from Jerry Schubert, who owned 1993 #397, as part of a big parts purchase from him. So, I went about putting together a clutch package as the pressure plate was the correct ZR-1 width. I knew from replacing the clutch in 'ol #458 that the standard LT5 clutch disk was better replaced with a sprung hub disc when installing a Fidanza Flywheel. I also learned a few other things that I didn't know about in the process.

I hope this information helps those that may be in process of replacing their clutch and flywheel and don't know the differences between the years and also may not have contact with others in the "know".

Here goes:

Fidanza Flywheel
You need to take a rat tail file to the dowel hole and open it up towards the outside of the wheel. As you do this, you can feel the fit get better. Use 7/16" x 20 x 1 1/4" Grade 8 bolts and thicker washers than what comes with the flywheel, they are available from most anywhere that carry bolts.
Use "RED" locktite on the bolts. This is in the FSM.

Pilot Bushing
There are three available for the ZR-1.

• Standard Bronze Bushing
• Fluted Bronze Bushing (I used this one upon Jeff Flint's insistance, he felt strongly enough that he sent me one, I now owe him!!!)
• Roller Bearing Bushing (GM Recommended Replacement)

Mine was a pain getting out. We got a Harbor Freight remover with several collets and a slide hammer. We couldn't budge the bushing with this kit and we banged on the slide hammer hard. We then got a Snap-On #A78 pilot bushing tool and used the long jaws. I had to tap the long jaws into the opening as they were a bit too large, but I got it in and didn't mess anything up.

DO NOT USE THE METHOD OF FILLING THE CRANKSHAFT AREA WITH GREASE AS THERE IS A SEAL BEHIND THAT AREA. YOU WILL HAVE A MUCH BIGGER PROBLEM TO FIX.

Measure the distance from the crank end to the face of the pilot bushing before you remove it so you will know when it is in far enough.

Clutch Pressure Plate
All pressure plates are Valeo or a derivative, so the only thing you need to know here is whether you have the LT5 or LT1 plate. The LT5 plate is thicker than the LT1. Hold them up side by side and if you have the LT1 plate you will need shorter bolts. MAKE SURE YOU LOOK.

Clutch Disk
I had a vibration through the car when I replaced the clutch on #458 and I felt pretty sure it was from using the Fidanza Flywheel with a stock LT5 clutch disk. I didn't know this when I replaced the parts or I would have gone with a sprung hub disk instead. There is no give in the system anymore with the Fidanza/LT5 setup. I used the Stage II clutch disk from Carolina Clutch, it is $150 Shipped, and I have no vibration this time.

Centerforce and McCloud both make a sprung hub disk but they are more expensive.

Clutch Release/Throwout Bearing
This is the biggy and for those that don't know, a change was made sometime in late 1993 to these bearings. I looked at the parts PDF and there was no break in the bearings. They were listed as '90, '91-'93 and '94-'95, so I figured, cool, only have to buy a clutch disk, NOT.

• The late '93, '94-'95 bearings are smaller inside diameter than the '90-Early '93 bearings.
• The late bearings have a teflon coating on the inside of the bearing.
• The late bearings WILL NOT WORK with the '90-Early '93 transmissions as the input shafts are larger.
• A very simple thing is try the release bearing on the input shaft BEFORE you try to install the transmission, duh.

You probably won't be able to find the release bearings separate from the clutch kits, at the major part stores, I couldn't.

I ended up ordering one from The Partsladi on ebay, cost was $105 shipped by priority mail and it was here in Idaho (from Florida) in two days. The early release bearings are AC Delco part no. CT-1073 and the parts PDF shows no AC Delco number for the late release bearings.

That's about it. I now have over 100 miles on the setup and am very happy with it. Total cost to replace the clutch was around $250 as I had the pressure plate already.

[Dynomite]

Thanks for the details....appreciate the write up

[Hammer]

Originally Posted by Dynomite

Thanks for the details....appreciate the write up

No problem, hope it might help at least one "Bro".

[Dynomite]

Originally Posted by Hammer

Fidanza Flywheel
Is this the same flywheel as you used? What is a good offer?
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=310087280116&viewitem= &sspagename=STRK%3AMEWAX%3AIT

You need to take a rat tail file to the dowel hole and open it up towards the outside of the wheel. Dowel is on crank shaft that locates flywheel. Elongate dowel hole on new Fidanza flywheel towards outside diameter.
Use 7/16-20 x 1 1/4 inch Grade 8 bolts and thicker washers than what comes with the flywheel for the crank shaft. Use stock grade 8 bolts for the stock LT5 preasure plate.

Pilot Bushing
Fluted Bronze Bushing (I wonder if Jeff will give me the same deal?)

Clutch Pressure Plate
The LT5 stock pressure plate is thicker than the LT1 pressure plate. Use the stock LT5 pressure plate.

Clutch Disk
There is no "give" in the system with the Fidanza/LT5 original clutch disk setup. Using a sprung hub disk from Carolina Clutch in combinaton with the stock LT5 pressure plate provides sufficient torsional "give".

I used the Stage II clutch disk from Carolina Clutch. Call them for part number.
http://www.carolinaclutch.com/

Clutch Release/Throwout Bearing
Is this the Clutch Release Bearing you bought? http://cgi.ebay.com/ebaymotors/89-90-91-92-93-Corvette-Zr1-Clutch-Release-Bearing-OE_W0QQcmdZViewItemQQhashZitem5d252558f0QQitemZ400 055163120QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcces sories

I assume thepartsladi clutch master cylinder and clutch slave cylinder will work with this setup?

Just some specific questions in red so I understand the details

Questions edited after receipt of PM (post #5)

[Hammer]

Originally Posted by Dynomite

Just some specific questions in red so I understand the details

Sent you a PM with answers.

[Dynomite]

Originally Posted by Hammer

Sent you a PM with answers.

Got PM and thanks again for the detail
Post #4 edited just a bit after receipt of your PM

All questions answered.....you "nailed" it....but then again you are the "Hammer"

[Scrrem]

Man, this post came just in time. Will tackle this task in a couple of weeks with the WAZOO crew, will let you know.
Rich

[Dynomite]

Originally Posted by Hammer

Sent you a PM with answers.

What bolt torque did you use for the 7/16-20 x 1 1/4 inch Grade 8 bolts (Aluminum flywheel to crank shaft)?

What bolt torque did you use for the 3/8-16 X 2-1/8 inch grade 8 bolts (pressure plate to Aluminum flywheel)?

I assume Red Loctite on everything?

[Hammer]

Originally Posted by Dynomite

Don't remember right off, they are in the FSM, Red Loctite.

30 Ft/Lb, I remember this because it's so low. Had to recheck to make sure I had the torque right. Metal bolts to aluminum flywheel. No loctite.

I assume Red Loctite on everything?

See above

[Dynomite]

Originally Posted by Hammer

30 ft-lbs for the 3/8-16 X 2-1/8 inch grade 8 bolts (pressure plate to Aluminum flywheel). I remember this because it's so low. Had to recheck to make sure I had the torque right. Metal bolts to aluminum flywheel. No loctite.

Hmmm??? The Service Manual Supplement suggests Loctite 262 Red on almost everything that you do not remove from time to time. Most of that stuff is Aluminum. For those items that you might remove from time to time (water pump, plenum for example) use Loctite 242 Blue

There are some stainless steel bolt kits and apparently stainless steel bolts in aluminum is subjected to galling. Some use anti-sieze on those fasteners.

I also see in this manual (I assume this applies for the flywheel bolts regardless if the flywheel is aluminum or steel) that the torque for Flywheel Bolts (7/16-20 x 1 1/4 inch Grade 8 bolts Aluminum flywheel to crank shaft) is 66 ft-lbs