6 spd manual -clutch replacement

[dpain]

Today I pulled the 6 sp manual transmission on my 2002 Silverado 2500 HD 6.6 Diesel. The throw out bearing had exploded and scattered parts all over the inside of the bell housing. Prior to that the clutch worked fine with the occasional clutch chatter starting out and a lot of noise from the throw out bearing. It had minor to mild vibration at idle which smoothed out at speed. I have a new clutch kit with a t/o bearing-slave cylinder a pressure plate and clutch disc.
The flywheel is in 2 parts which gives me 2 questions.
1-The part of the flywheel attached to the engine has a sprung disc attached to it. Does that need to be serviced or checked in any way. All springs are complete.
2-The friction part of the flywheel has some burn spots (temper discoloration) and seems slightly uneven. Will surfacing that at the machine shop make the flywheel as good as new or should it be replaced. If it is replaced are both parts replaced including the spring disc.
I have 160,000 original miles on the clutch and would like to be that lucky with the replacement clutch.
thanks

[More Power]

GM made a mistake by trying to employ a dual-mass flywheel in the Duramax. They made the same mistake when they designed the same parts for the 6.2/6.5 diesel engines. Like the more recent 6.2/6.5 flywheels, the latest and best Duramax flywheels are of the single-mass type. I'd recommend getting a new kit with all new parts like those from www.thoroughbreddiesel.com/south-bend/duramax-single-disk.htm (http://www.thoroughbreddiesel.com/south-bend/duramax-single-disk.htm).

Always install a new pilot bearing when the trans is out of the truck.

Jim

[dpain]

It sounds like the dual mass flywheel has problems for some people. My clutch has lasted over 160,000 mi. so it must be working for me. I've already invested in a new one so I'm stuck. Any advice on removing the old flywheel. I have a 3/4" and 1" impact gun and a 3/4" drive 14mm hex socket that will fit the flywheel bolts. Any chance that the monster impact will damage the bearings or seals when I remove the bolts.
Thanks

[DmaxMaverick]

It sounds like the dual mass flywheel has problems for some people. My clutch has lasted over 160,000 mi. so it must be working for me. I've already invested in a new one so I'm stuck. Any advice on removing the old flywheel. I have a 3/4" and 1" impact gun and a 3/4" drive 14mm hex socket that will fit the flywheel bolts. Any chance that the monster impact will damage the bearings or seals when I remove the bolts.
Thanks

[incorrect information, corrected below]

[dpain]

I have seen some chatter about how tough it is to remove the flywheel bolts. Numbers like 190 to 350 ft lbs to torque them. Are we talking about the same bolts that hold the flywheel to the end of the crank. They are some pretty meaty bolts.
David

[DmaxMaverick]

You are correct. The previous info I posted was incorrect.

The spec and procedure is as follows:

(use a criss-cross pattern throughout the procedure)
Torque to 58 ft/lb.
One pass, tighten 60°.
One more pass, tighten another 60°.

These bolts are TTY (Torque To Yield), and CAN NOT be reliably reused. I know a bunch of people who have with no problems, but as a general rule, do not reuse TTY's. If you insist on reusing the bolts, DO NOT follow the above procedure. If you do, the bolts WILL fail during the install, or shortly after.

I have no idea what the torque might be on reused bolts. Contrary to common myth, you can not determine tightening torque by measuring removal torque. If it were me, and I were required to reuse them (emergency, etc.), I would mark the bolts/flywheel, count the removal turns, and put them back where I found them (using Loc-Tite). NOT an easy task, with 8 bolts in symmetry.

[dpain]

Thanks. I will install asap.
David

[JohnC]

You should be able to determine the correct torque based on the diameter and grade of the bolt. Use at least blue loctite.

[DmaxMaverick]

You should be able to determine the correct torque based on the diameter and grade of the bolt. Use at least blue loctite.

Add thread pitch to your list.

This doesn't apply to TTY bolts. They've been stressed and work hardened beyond the scale. A best guess would probably work as well as anything.

[JohnC]

A best guess would probably work as well as anything.

My best guess would be based on diameter, grade, and yes, thread pitch... ;)

[dpain]

OOO yeahhh.
Shure is sweet when it goes together and works better than expected.
After 160,000 mi of progressive deterioration the clutch finally went out but for the last 40k the clutch has been marginal and shifting difficult. The flywheel was out of balance and the t/o bearing on the verge of failure so it made a racket in neutral and ran rough. Things still worked so why pull the trans. When the t/o bearing finally blew up I had no choice.
I replaced the clutch master cylinder and hydraulic hose The dual mass flywheel, clutch and slave cylinder with throw out bearing. And a oil change in the 6-speed.
The test drive was amazing.
The clutch engaged smoothly with no vibration. The new flywheel spun like it was supposed to with no low speed vibration. The transmission is so smooth I can shift easily.
Which brings me back to the purpose of this post. NO CRANK.
I could not crank the engine from the key switch. The new clutch master cylinder comes with a new interlock switch. When everything was replaced I ended up fixing the original problem that started almost 3 months ago.
After years of working on vehicles this is the best.
David

[More Power]

I have no idea what the torque might be on reused bolts. Contrary to common myth, you can not determine tightening torque by measuring removal torque. If it were me, and I were required to reuse them (emergency, etc.), I would mark the bolts/flywheel, count the removal turns, and put them back where I found them (using Loc-Tite). NOT an easy task, with 8 bolts in symmetry.

The flywheel bolts used on the 6.5L diesel are torqued to 65 ft/lbs - they are not TTY. The Duramax uses larger bolts, so it's a guess what non-TTY bolt torque might wind up being. Someone installing them could find out by using a torque wrench when making the final angle tightening... But, like you suggested, the best course of action is to just use new bolts.... ;)

Jim