Author Topic: Flywheel mounting bolt torque predicament (Read 3716 times)

jackbombay · « **on:** April 18, 2005, 09:35:00 pm »

I am installing an older Turbo Diesel into a VW quantum syncro and the audi motor had "non-shouldered" bolts that held on the flex plate. I used the flywheel from the motor that was originally in the Quantum, thoes bolts are shouldered.

When I installed the flyheel on the Diesel I looked at the torque spec in the Audi manual, 53 Lb/Ft. I used the red loctite (271) as reccomended.

Today I was looking through the Quantum manual and I found 2 different troque figures for the flywheel, 53 for non shoulderd bolts and 72 for shouldered bolts. Well I used the shouldered bolts because there was no oil on them, but I only torqued them to 53 lb/ft like the Audi manual said, that manual does not have a spec for shouldered bolts, and the Audi motor did not have shouldered bolts to begin with.

I can see where the clamping force of the bolt is spread over a larger area with the shoulder and why they would need more torque, but damn I really don't want to pull the engine again, probably 2 hours in and out at this point

What would you do?

dieselweasel · « **Reply #1 on:** April 18, 2005, 09:41:06 pm »

I think I'd leave it, especially since you used red loctite.

racer_x · « **Reply #2 on:** April 19, 2005, 04:42:04 am »

That's a tough call because the torque spec is significantly higher on the shouldered bolts.

If it was my own car, and I was going to be the only one mad at myself if/when it became a problem, I'd probably run with it and not bother.

If that was someone else's car (a friend or neighbor) and I did that, I'd be taking it back apart and doing it right.

If/when those bolts fail, it can really tear up the transmission bell housing and damage a lot of stuff (including the end of the crank).

Mark(The Miser)UK · « **Reply #3 on:** April 19, 2005, 03:29:16 pm »

Quote from: "jackbombay"

I am installing an older Turbo Diesel into a VW quantum syncro and the audi motor had "non-shouldered" bolts that held on the flex plate. I used the flywheel from the motor that was originally in the Quantum, thoes bolts are shouldered.

When I installed the flyheel on the Diesel I looked at the torque spec in the Audi manual, 53 Lb/Ft. I used the red loctite (271) as reccomended.

Today I was looking through the Quantum manual and I found 2 different troque figures for the flywheel, 53 for non shoulderd bolts and 72 for shouldered bolts. Well I used the shouldered bolts because there was no oil on them, but I only torqued them to 53 lb/ft like the Audi manual said, that manual does not have a spec for shouldered bolts, and the Audi motor did not have shouldered bolts to begin with.

I can see where the clamping force of the bolt is spread over a larger area with the shoulder and why they would need more torque, but damn I really don't want to pull the engine again, probably 2 hours in and out at this point

What would you do?

:twisted: Do you have another engine nearby with a flywheel exposed? If you have then use that for an experiment if not then find a similar sized bolt and hole..Torque experimental bolt up to the 53 lb ft using the loctite... Leave 24 hrs and then check torque needed to release. Keep yourself busy sorting out your battery location?? Experiment with different torques and with/without loctite. Post results for me to assimilate :twisted:

jackbombay · « **Reply #4 on:** April 19, 2005, 06:13:25 pm »

I got some non-motor related stuff done today to avoid making a descision on this. I think I am going to pull the motor and retorque the bolts, it would eat at me forever if I didn't...

veeman · « **Reply #5 on:** April 20, 2005, 01:23:25 pm »

I know what you mean... why risk it, right?

While you're in there this time, did you replace that rear main seal ? Grease the pilot bearing (it's in the flywheel in the Audi's) for the input shaft?

Cheap insurance. Those are two things that would definitely rain on your parade if they fail...

jackbombay · « **Reply #6 on:** April 20, 2005, 01:29:46 pm »

New rear main and a new pilot bearing already installed.

I am going to pull the motor and retorque the bolts...

Mark(The Miser)UK · « **Reply #7 on:** April 20, 2005, 02:07:49 pm »

Quote from: "jackbombay"

New rear main and a new pilot bearing already installed.

I am going to pull the motor and retorque the bolts...

For scientific interest; check torque to undo :lol:

jackbombay · « **Reply #8 on:** April 20, 2005, 03:07:34 pm »

My torque wrench does not work in reverse so to speak, they seemed to "crack" easier than I was expecting, but they were fairly difficult to "spin" out thanks to the locktite.

All better now, just need to reinstall the motor....

EDIT- 2 hours total to get back to where I was, worth it considering all the future hours I would have worried about it had I not done it right...