Clutch replacement

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McCall Pinz
Switzerland
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Clutch replacement

Post by McCall Pinz » Mon Jan 23, 2017 3:31 pm

I posted a while ago about a mystery clunk on startup. The loud clunking occurred when starting the engine with the clutch depressed, but the truck started silky smoothly in neutral. There were lots of good suggestions- motor mount, rear gearbox mount, shifter linkage, loose starter, loose solenoid, etc. After making sure it wasn't any of those things, I decided to pull the gearbox and clutch. When looking through the inspection cover, there were shiny aluminum shavings visible in the dust... not a good sign. The inside also looked oily... also not a good sign.

There's a lot of info in different threads about the clutch and gearbox, but I didn't find one about pulling it out and working on it. Maybe this can become one spot for all that knowledge? Feel free to add ideas and this can become a tech article.

Step 1. Remove the seats, doghouse, and rear access panel in the bed of the truck
Step 2. Carefully support the engine under the oil pan with a floor jack
Step 3. Support the gearbox with another floor jack or with a strap from above. This might also be a good time to drain the gear oil and use it as a chance to refill it with Redline MT90 per all the suggestions on this forum.
Step 4. Put the gearbox in neutral and disconnect the shifter linkage on top
Step 5. Remove the 4 large nuts around the bellhousing and the 2 bolts at the starter. In my case 1 of the nuts came out with the stud, but that's not a big deal.
Step 6. Remove the 6 nuts and bolts at the cardan shaft at the rear of the gearbox.
Step 7. Verify your supports or straps and then remove the 4 bolts fastening the rear gearbox mount to the center tube. The gear box should be loose now.
Step 8. Pull the gearbox rearward to clear the studs and carefully lower it to the ground.
Step 9. Block the clutch from turning with a wrench against one of the studs. Loosen the 6 bolts around the perimeter of the pressure plate and remove the clutch assembly. If necessary, tap the clutch assembly with a rubber mallet or gently pry along the edge with the flywheel.

So it is now removed and I've found the source of my mystery clunk...
Attachments
Access panel removed.jpg
Access panel removed.jpg (1.06 MiB) Viewed 2896 times
Ready to pull.jpg
Ready to pull.jpg (1002.95 KiB) Viewed 2896 times
Throwout bearing.jpg
Throwout bearing.jpg (728.42 KiB) Viewed 2896 times
Leak from clutch slave.jpg
Leak from clutch slave.jpg (890.15 KiB) Viewed 2896 times
Exposed flywheel.jpg
Exposed flywheel.jpg (594.5 KiB) Viewed 2896 times
Last edited by McCall Pinz on Mon Jan 23, 2017 5:50 pm, edited 2 times in total.
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McCall Pinz
Switzerland
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Re: Clutch replacement

Post by McCall Pinz » Mon Jan 23, 2017 3:34 pm

My mystery clunking was from a broken pressure plate- sheared in two.
Attachments
Broken pressure plate.jpg
Broken pressure plate.jpg (884.45 KiB) Viewed 2893 times
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McCall Pinz
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Re: Clutch replacement

Post by McCall Pinz » Mon Jan 23, 2017 3:39 pm

What do you guys think about the inside of the bellhousing? I think they should be dusty, but dry in there. I'm sure my clutch slave is leaking a tiny amount. Could the oily residue be from the slave cylinder? Should I pull the flyweel and look at the main bearing seal since I've gone this far?
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edzz
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Re: Clutch replacement

Post by edzz » Mon Jan 23, 2017 10:38 pm

McCall Pinz wrote:What do you guys think about the inside of the bellhousing? I think they should be dusty, but dry in there. I'm sure my clutch slave is leaking a tiny amount. Could the oily residue be from the slave cylinder? Should I pull the flywheel and look at the main bearing seal since I've gone this far?

The only time I did a clutch job and didn't surface the flywheel I had clutch chatter afterwards.

Since you have it this far apart if it were me I would replace the rear main seal, resurface the flywheel and replace or rebuild the slave cylinder.

Good time to replace the dog-bone bushings if you haven't done them yet.

73 Ed
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TechMOGogy
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Re: Clutch replacement

Post by TechMOGogy » Tue Jan 24, 2017 8:23 am

Looks like this could be moved to the Tech Sessions area!
Thx for posting
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waterdog
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Re: Clutch replacement

Post by waterdog » Tue Jan 24, 2017 11:17 am

do you think is absolutely necessary to remove the rear Access panel to remove the tranny??? or you can get away removing all bellhousing bolts from underneath??? im asking cause my floor is furnished and carpeted :? :?
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McCall Pinz
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Re: Clutch replacement

Post by McCall Pinz » Tue Jan 24, 2017 11:25 am

It might be possible, but I think it would be VERY difficult to detach the shift linkage which is located on top of the gearbox. One bolt is accessible from below, but I don't know if the 2nd one is accessible from the engine compartment. The previous owner spray-lined the truck bed area and it took a while to remove the coating from the screw heads, but I think it was worth it- especially because I only have 1 real floor jack.
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pinzinator
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Re: Clutch replacement

Post by pinzinator » Tue Jan 24, 2017 7:59 pm

What is the torque specification for those 6 bolts that hold the flywheel to the crankshaft? Are they hard to loosen?

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Hotzenplotz
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Re: Clutch replacement

Post by Hotzenplotz » Wed Jan 25, 2017 2:47 am

Pinzinator

take an impact wrench; or use a pipe on the wrench.

Installation is easy

use NEW bolts, fasten with 30 Nm in the first go, then 50 Nm, then turn each bolt another 60°.
I placed a mark with a felt tip pen on each bolt that was done

Image

yes, make sure you block the front end of the crankshaft if you don't have that blocking tool ...
Cheers
Albert
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pinzinator
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Re: Clutch replacement

Post by pinzinator » Wed Jan 25, 2017 10:17 am

50 Nm is about 38 ft-lbs of torque, adding the 60 degrees might double it. I am curious as to why the bolts should be replaced with so little torque applied, and torque stretches the bolt. Not arguing with the guys who design this kind of stuff, just wondering out loud.

I also assume Loctite should be used.

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McCall Pinz
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Re: Clutch replacement

Post by McCall Pinz » Wed Jan 25, 2017 11:32 am

I'm having an internal debate to do this further work right now. For any leak to be properly fixed, the flywheel should come off, the seal replaced, and the bolts replaced too. I'm trying to verify if there's a leak in the seal now.

PS- $14.63/bolt at SAV or they have USED ones for $11.00. I'm not sure if that means I can re-use them?
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Haf-e
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Re: Clutch replacement

Post by Haf-e » Wed Jan 25, 2017 1:27 pm

The torque being applied to move the bolt another 60 degrees will be high since it is starting out at 50 Nm already. Reusing old bolts is probably OK but there is a risk of them breaking which would involve extracting broken off part... hard to know if its worth it or not. $100 USD to prevent a problem!
Haf-e

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Hotzenplotz
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Re: Clutch replacement

Post by Hotzenplotz » Thu Jan 26, 2017 5:54 am

There are different ways of reading a manual ...

there are stretching bolts you can easily access like the ones in the drive housing.
if you regularily have a look at them, the risk of reusing a stretched bolt is acceptable to some

try that with the flywheel ,,,
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rmel
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Re: Clutch replacement

Post by rmel » Thu Jan 26, 2017 10:58 am

A 60 degree turn amounts to 0.25mm "stretch" (I think these bolts are 1.5mm thread).
I wonder what the hardness of these bolts are 10.9?
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McCall Pinz
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Re: Clutch replacement

Post by McCall Pinz » Mon Jan 30, 2017 11:49 am

Very little progress this weekend, but it was interesting...
After making an extremely simple version of the flywheel locking too, my son and I pulled the flywheel. The "tool" is a scrap of aluminum and 2 random holes. Per an old Jim L. thread, we heated the bolts to soften the Loctite and they came right out quite smoothly. There was no real "breaking" of the bond just a smooth pull with the torque wrench. The markings on the head are RIBE 12.9 and the manual indicates they're 14mm x 1.5 pitch. 12.9 is the Extreme Strength rating. Also, they're 50mm long under the head. In addition to that big size they have an interesting profile. It really looks like they're designed to stretch a very specific amount. In the old post Jim L. mentions re-using them with a drop of loctite on the threads and under the head, but I think some new ones from SAV are in order.

The rear main seal looks fine to me. You can see that the "oil" in the housing is coming from the slave cylinder (above the starter). All the parts are on their way now.

FWIW, the stock flywheel weighs 27.5 lbs (12.47 kilos) on my bathroom scale. Classic SuE runs a lightened one that looks like it is 8.86 kg or 19.53 lbs. Anyone running a lightened flywheel here? Based on past results with aircooled VWs that can make a big difference to the torque curve and how quickly the motor revs up... usually at a cost to the top end or fuel economy though.
Attachments
HeatingFlywheelBolts.jpg
HeatingFlywheelBolts.jpg (126.16 KiB) Viewed 2598 times
BreakingLoose.jpg
BreakingLoose.jpg (145.87 KiB) Viewed 2598 times
RearMainSeal.jpg
RearMainSeal.jpg (137.24 KiB) Viewed 2598 times
UniqueBolts.jpg
UniqueBolts.jpg (268.21 KiB) Viewed 2598 times
Stock Flywheel.jpg
Stock Flywheel.jpg (62.51 KiB) Viewed 2598 times
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