devilinblack

Backstory:

1978 US 5-speed. Purchased in August of this year and driven intermittently since then due to catching up on maintenance and repairs. Car has had a bad vibration at 4000 rpms since I purchased, but otherwise it shifts fine and the PO claimed to have recently rebuilt the clutch.

While diagnosing a poor running/stumble condition the other day I started to get a new noise from the clutch area, similar to marbles in a metal bowl. Fixed the stumble (bad EGR FWIW) and jacked up the front end to see what I could find about the new noise.

Found a hole blown in the lower bellhousing. Pulled out the slave cylinder and found an odd wear mark on the shaft. I've got the starter unbolted and I'll drop the bellhousing tomorrow, but I wanted to see if anyone had any ideas of what I'm likely to find when I get it apart.

The clutch still works, aside from the odd rattling noise it seems okay.

Here's a couple photos. I'll update with more details and photos as I go. Wish me luck!

SharkSkin

Pull the airbox and look at the release arm pivot ball at the top of the bellhousing -- it's 180° away from the clutch slave, visible from the driver side. The ball may have broken off or beat up the threads until the ball popped out, allowing the release arm to twist around and slam against the lower BH. Then, being out of position, it may have allowed the starter ring to grind on the clutch slave rod. Look on the bright side -- you're halfway to having an inspection hole for adjusting your clutch!

I'm knee-deep in my own clutch, when I gave my first tug on the release arm to disengage it from the pivot ball the ball slid right out of the threaded hole. Well, the hole used to be threaded anyway; it's now more of a conical shape from what I can tell from below, trying to fit the ball back in place.

Time for a new upper BH and of course a new release arm in my case. PO or PO's mechanic seem to have installed late TO bearing with early release arm, which probably didn't help matters... TO bearing seized but fortunately it only seems to have damaged guide tube and PP fingers.

Moral of the story -- you never know who's been monkeying with it. Check everything carefully and refresh with ALL of the correct parts.

devilinblack

Okay. got the lower bellhousing off this morning and found this bolt rattling around in there.



Looking at the clutch I'm pretty sure where it came from.



Is the silver collar the guide tube? The PET does not seem to show those bolts but I'll look in the WSM and see what I can figure out.

Anyone have a good photo of what that area is supposed to look like and an idea of what else I may be missing?

Thanks.

Mrmerlin

the bolt looks like a bolt for holding the pressure plate, spin the engine by hand and check for a missing bolt, if you dont find anything then the bolt may have dropped in from the top pivot hole on the release arm.
The guide tube bolts are both missing these need to be refitted 6mm bolts with 10mm heads you might have to loosen the clamp bolts ( to slide the connecting clamp back) to fit the bolts in from the back to secure the tube to the housing. You will probably need a new lower housing

devilinblack

Yes, I'm thinking the bolt I found is one of the guide tube bolts as it does fit in the guide tube. I'm guessing both fell out and one made a quick exit through the bellhousing and the other stayed behind to rattle around?

I found the correct page in the WSM so I'll post again when I know more.

Mrmerlin

from the pictures the bolt you found does not look like the it came from the guide tube

devilinblack

The bolt in question is a 6 x 16 Hex head (10mm head). I don't see any other bolts that size in the PET. The ball pin is also 6mm, but that would have a ball head attached to the bolt, wouldn't it? I rotated the engine by hand and don't see any other obviously missing bolts in there. I replaced the two 6mm bolts with new stainless 8.8 bolts. I also re-torqued the clamping sleeve bolts.

After reassembly it still seems noisier than it should both with the clutch released and while it's pressed in. I'm going to bleed the system tomorrow and check the adjustments per the WSM and see if that helps. I was about to say I could start it with the lower bellhousing off to see what might be rattling, but obviously that's not possible since the starter is on the bellhousing. Duh!

SharkSkin

That's a guide tube bolt. Is the guide tube well lubed? Did you check the release arm pivot? Bleeding and adjusting will have no effect on the noise you're hearing.

It looks like there is a crud buildup under the arm on the rear face of the TO bearing. A guess -- maybe the TO bearing has dried out? Either way, TO bearing is suspect if you have noise with pedal up or down. Be sure to mark all rotating parts so you can get them back in the same orientation on reassembly. Check the pilot bearing WYAIT(I'd replace it unless it looked brand new. In fact mine feels new and I'm replacing it; it has 30K on it minimum) and look for wear on the short shaft splines. Lube per WSM recommendations on reassembly.

Can you see any evidence that a guide tube bolt got wedged between the clutch and the housing? or any other evidence as to what may have caused the damage?

Something is definitely wrong, it looks like the release arm has been dragging on the PP fingers.

You should be able to push start the car with the lower bellhousing off, but you'll have to bolt the large B+ leads together and insulate that and the other wires. Then getting it back in the air and safe to get under, plus getting into that limited space with a meat grinder spinning overhead all carry risks. You can probably find out what you need to know by having someone turn the crank via the crank bolt and by reaching up in there and pushing things around to see what has play. I find it hard to imagine how a loose guide tube(alone) could hole the BH and cause the damage you saw on the slave rod. You need to either find out what really happened and/or examine the individual parts.

Jim bailey - 928 International

The forward bearing carrier in the torque tube has probably migrated back to the middle of the tube .That leaves the clutch unsupported and it vibrates out the guide tube bolts ..... I wish I had looked at this thread sooner.

mark kibort

yep, guide tube bolts. (quick verification is that they will have the 10mm socket head)
dont worry about the pressure plate marks, thats normall wear. dont worry until those marks become deep grooves. Ive seen that on all the clutches ive pulled out.

mk

SharkSkin

Mark, I disagree about the marks on the PP being "normal wear". Those are not from the spring washer, those are far up the fingers and IMHO indicate that the release arm has been dragging on the fingers.. Bad as my clutch was, with seized TO bearing, badly worn guide tube and beat to **** ball pivot threads, it has no such marks. They may have been caused recently by the lack of guide tube and migrated TT bearing as Jim speculates but they are not at all normal IMHO.

Mrmerlin

sorry about the mis diagnosis on the bolt
It does sound like a guide tube bolt. you should pull the cluthc out and check the TOB see if its dried up if so then a new one will be in order plus what Dave said about the pilot brg and if the input shaft isnt perfect this should also be replaced as well.
Make sure to use the Hi temp grease on the input shaft it will make it last longer before it starts to corrode.
A new lower bell should also be fitted ( used will work ) and if you can please post a picture of the PP fingers both sides.
take a mirror and look inside the TT see how far back the front bearing is IIRC it should be aboout 8 inches from the front

devilinblack

Okay, thanks for all the pointers everyone. I'll pull the clutch for inspection today and also check on the forward bearing in the Torque Tube.

Lizard928

you can actually measure the location of the forward bearing without dropping the clutch etc.

Jim bailey - 928 International

Just see how far down the tube you can poke a coat hanger wire....