Clutch fork travel

[DanEC]

Originally Posted by lippy

Dan, it shouldn't matter what gear it's in or even if the engine is locked. When I press the clutch with the trans in gear it should disengage the trans from the engine and I should be able to roll the car (or turn the wheels if they are jacked up). I can turn the wheels when it is in neutral, so I know there is no problem on that end. Thanks.

Lippy - you're right - other than what Jerry added in my defense my thinking took a detour.

Parking brake is off - right? I'm out of here.

Dan

[patrickt]

Originally Posted by DanEC

Parking brake is off - right?

I'm now waiting for the "oh yeah, parking brake, uhhhh wait a minute while I run out to the garage and check.... ahhh, jeez, I can't believe it...."

[DanEC]

double post

[Jerry Clayton]

Well---------------it does matter what gear your in because you are dealing with a new clutch with dual discs and a first time install-------- possibility of bent disc center, disc facing wrong way, hub not clearing bolt heads, etc, etc--------without the engine running/car rolling ot is a fairly common occurrence---there isn't enough movement to free the dual discs completely and you are dealing with the rear end ratio times the gear ratio of the gear the trans is in when you try to turn them-for example---a 3.90 rear gear times a 3.xx first gear would mean that you would turn the clutch discs aprox 12-14 revolutions for one rear tire turn-------

Also ---does the car have a posi???? both wheels off the ground???????
I would suggest getting under the car with a strap wrench around the drive shaft and see if you can turn the shaft with trans in the direct drive gear (what trans???? might be 4th with a overdriven 5/6 speed)

And you also can also try rotating engine with starter while clutch depressed /trans in gear

[blykins]

It could be that easy, but my only concern is that it's a stacking of tolerances between the bell, the trans, the block plate, etc, and that when he bolted the trans up, it mashed everything together. In that scenario, I wouldn't want him bumping the starter or starting the engine, just in case it's got the crank up against the thrust bearing.

[frdfver]

Its been my experience over the years if you have to pull the trans in with the bolts something is to tight or not right in the clutch, pilot bearing input shaft clearance, clutch hub spline interference, etc. I would also check the total travel on the slave by itself. It looks like the slave mount is held on the slave with clamp bolts, are they tightened down to tight deforming the cylinder?

Paul T.

[lippy]

Originally Posted by frdfver

Its been my experience over the years if you have to pull the trans in with the bolts something is to tight or not right in the clutch, pilot bearing input shaft clearance, clutch hub spline interference, etc. I would also check the total travel on the slave by itself. It looks like the slave mount is held on the slave with clamp bolts, are they tightened down to tight deforming the cylinder?

Paul T.

What I keep coming back to is that I get almost an inch of travel from the slave right now. Even more when I preload it. McCleod says I only need 0.35-0.4" at the clutch, and the fork ratio is 1.75:1. I should have more than enough travel. I'm suspecting it's something else, as you point out.

[lippy]

At Brent's suggestion, I pulled the trans mount bolts, supported the car and engine, loosened the trans bolts about 0.25", and pulled the trans back about that far. Everything worked fine. The clutch released, and there was plenty of travel at the throw-out bearing. As a check, I then pushed it back in so there was only about 0.1" between the bell and the trans mount, and it didn't release. It seems like there is something up with the pilot bearing. I also rechecked the clearance for the trans input shaft and it seems like I'm fine there. After that, I pulled the trans.

[lippy]

Originally Posted by frdfver

Its been my experience over the years if you have to pull the trans in with the bolts something is to tight or not right in the clutch, pilot bearing input shaft clearance, clutch hub spline interference, etc. I would also check the total travel on the slave by itself. It looks like the slave mount is held on the slave with clamp bolts, are they tightened down to tight deforming the cylinder?

Paul T.

Kudos to frdriver and Brent. I should've listened earlier. It turned out to be the bearing retainer jamming the clutch hub spline on the rearmost disk. I had a machine shop take off 5/16" from the end of the input shaft (3/32" interference I measured, plus 0.100" for clutch wear, plus a little safety) and got the whole thing back together. It seems to work perfectly. My only consolation is that I can now pull and reinstall the trans in this car relatively easily, and by myself.

[patrickt]

Originally Posted by lippy

My only consolation is that I can now pull and reinstall the trans in this car relatively easily, and by myself.

... and dead lifting a hundred pound anything, while standing/squatting in the car is nothing to sneeze at.

[tkb289]

lippy,

Sounds like you have found the problem area, seems like the transmission input shaft is engaging too far into the crankshaft / pilot bearing and bottoming out. Not sure which bell housing you have, but on page 12 of the ERA FIA manual (same as the 427 manual?) it states for the TKO 500/600 that some bell housings require a 5/8" spacer.

I used a quicktime bell housing & TKO 600 and had no fitment issues on my 302. What bell housing are you running on your 427?

If you pull the transmission all the way out, you should be able to measure how far the input shaft protrudes past the bell housing / engine block mounting plane. There should be a spec for what the maximum length is for that dimension. If it's too far, then you need the spacer.

[blykins]

No spacer needed here as it's a standard length TKO bellhousing with an RM-6056 Quicktime.

At least he's finding more clues though.

Here's a couple of thoughts that I have:

The portion of the input shaft where the pilot end meets the splined end is hitting on the pilot bushing, or the bearing retainer on the trans is hitting the pressure plate. A couple of quick measurements can rule both out.

He's already measured to make sure that the pilot end is not bottoming out in the crank, and a pilot bushing is thicker than 1/4", so I think the pilot is still in the bushing, even when he scooted the trans back.

[DanEC]

Originally Posted by blykins

or the bearing retainer on the trans is hitting the pressure plate.

Brent - do you mean hitting the outer clutch disc instead of pressure plate?

I notice that the bearing retainer is .6 inch longer on the GM version versus the Ford version. I don't guess you managed to get a GM version by chance?

http://www.jegs.com/p/Hurst-Drivelin...13608/10002/-1

[blykins]

Anything's possible. This is a collection of a bunch of aftermarket parts coming from 3-4 different manufacturers....

I've had issues with bearing retainers rubbing against fingers before, but yes, since there's another disc in the mix, it's possible the bearing retainer could reach in that far.

[lippy]

I will double check my clearances, but for now it looks like I damaged my pilot bushing during trans installation and that is causing the problem. I will replace it and reinstall everything carefully and we hope it will be ok.

[DanEC]

Lippy - I went back and skimmed this entire thread and I didn't see where the type of flywheel you are using was mentioned. I'm kind of assuming it's a McLeod flywheel that is typically paired up with this dual-disk clutch. But, there are several quality aluminum flywheels out there that various builders get attached to. I remember reading that sometimes dual disk clutches are paired with flywheels that are thinner than what is usually used for a singe disc clutch - to offset the additional thickness of the pressure plate and disk assembly. It's possible the root cause of this is a flywheel that is possibly a little too thick for use with this clutch - which would set the clutch pack to the rear in the car - thus possible interference with the bearing retainer. Even if this is so, by shortning the retainer the problem should be solved.

I don't envy you having to muscle that transmission out and back in again.

[Jerry Clayton]

when you make up the dowels out of long bolts , make them different lengths so its easier to start the trans sliding over them--its easier to hit one hole at a time

[frdfver]

Slip fit that new bearing on the input shaft, Check the input shaft, not machined right, scored, end mushroomed-bent, maybe dropped or during shipping.

Paul T.

[lippy]

All good tips, thanks. I'm sure this was me and not Brent, btw.

While I had the trans off and waiting for parts, I checked the fork movement at the input shaft with a dial gauge and I got 0.40", so I should be good to go there. I also adjusted the slave rod and know that the throw out bearing won't be resting on the clutch. I also checked clearances at the end of the input shaft, and at the end of the splines and there doesn't seem to be a problem with either. Hopefully I can get this corrected this week, with a little luck.

[lippy]

I'm totally bummed. I removed the trans, removed the clutch, installed a new pilot bushing, and reinstalled everything, which wasn't super easy by myself. I checked all of the clearances twice, and everything seemed ok. Put it all back together and with a lot of work I got it to align and slide all the way on without using the bolts to pull the trans in. Still, the clutch doesn't release. I'm getting 0.9" of travel at the slave, which is more than enough according to Bob and Doug at ERA, and the tech guys at McLeod. But... when I back the trans bolts out 3/32" and move the trans back on the bolts, it seems to work. I don't think it's an issue of needing an extra amount of travel for the fork, because I preloaded the slave rod by more than that amount, and it still didn't work. Does this imply there is some sort of interference issue with the input shaft?