belgiquebasterd

Clutch burned up and put in new discs and floater plate, now clutch won't disengage fully, I can get it into 1st with some force but something is clearly wrong.

Things I checked:

- disassembled everything to check I didn't mess up disc orientation during install.
- reassembled using an old input shaft not the plastic thing. After clutch installation input shaft slides in and out the clutch without effort.
- double checked the clutch finger height as per ACT instruction
- set floater plate preload correctly
- shimmed the slave cylinder
- installed new master cylinder
- **** still wont work

I'm pretty sure it's not a hydraulic problem, see the short movie attached, you'll see there is plenty of travel on the slave cylinder. Any ideas as to what might be wrong?? Thanks.


Parts list:

- ACT twin disc clutch
- quicktime bellhousing
- viper truck T56 trans

Video:

http://vid292.photobucket.com/albums...psfgnf7oxt.mp4

pdxmotorhead

Did you change the pilot bushing/bearing??
Every clutch Ive burnt up the pilot was dry...
I think the heat just cooks the lube.

The drive splines on the disks, where they slide against their mates both need to be smooth, are there any grooves? and are they installed the same clocking as they were originally?

belgiquebasterd

Did not change the pilot bearing, it's a roller bearing and there was still grease one, looked perfect, when I pull the transmission again (4th time now :-) ) I'll swap it out just to be sure, what type of grease would be ideal for it?

The discs are brand new as is the floater in between, am not 100% sure but don't think the discs touch each other. Either way they are in perfect condition, the splines on the trans input shaft haven't got any burrs or deformation that I can see.

Darth_V8r

iTrader: (4)

I'm not convinced this your issue but it is a habit I have that will be worth doing.

Put some valve lapping compound on the input shaft. Put one of the discs on and go back and forth to polish the input shaft. Then repeat with the other disc. Use several different clock positions. Thoroughly clean the compound off the disc splines and input shaft. Lightly grease input shaft. That will pretty much guarantee smooth engagement and disengagement.

When you measured for slave shim, did you fully compress the slave to take measurements?

BALLSS

I suspect the hydraulics are not completely bleed.

If the pilot bearing looked good, it should be OK. If you are pulling the trans again you can replace it

Given you have a new MC and slave, sounds more like a hydraulic issue, bleed it

Edit:

Agree with Darth comment about having the input shaft splines, and disc, clean and then with a light coating of grease on the input shaft so discs do not bind on the input shaft.

Also confirm splines on input shaft are not tweaked (twist)

belgiquebasterd

Lapping compound is a good tip, will do that for sure! Slave was definately fully compressed, removed the spring and I could feel it bottom out when compressing.

belgiquebasterd

Have you seen the video in the first post? I was in contact with ACT and according to them the clutch fingers need to be depressed about 8mm for the pressure plate to completely disengage, looks to me on the video it's got way more travel than 8mm. I got a cheap boroscope cam ordered once I get that I'll probably be able to film and measure the slave travel at the same time.

I got quite a bit experience with bleeding brakes n stuff, and a bleeding problem was also my first thought. I then changed and bench bled the master, pushed the oil up from the bleed nipple through the slave to the MC, and then did a couple of cycles the old fashioned way by pumping the pedal until I have absolutely no more bubbles coming out. Pedal also feels really good, never say never but I'd be surprised if it was a bleeding problem. Don't really know what else I could do to bleed them better.

BALLSS

yeah video looks like there is way more than 8mm of slave travel.....maybe the PP is over extending??

although if that was the case causing a disengagement issue I would think just partially pushing in the clutch pedal would work if over extending the PP is happening and would cause disengagement issue. IDK if it would

is the slave the same height as the stock one?

stevieturbo

Get the camera...or some form of access to the clutch.

Have someone jam down the pedal and view the actual discs. Whether through the starter hole, drill a hole in the BH, or whatever, but get a good clear view.

You will be able to see if each disc is releasing, or better still poke a thin screw driver through and see if the discs are actually free to rotate.

I used the ACT twin for a few years, and for the first few it was great, but over time it just started dragging.

I'm pretty sure I had too much travel at the slave ( non OEM fitment ), which may have caused part of the issue over time, maybe over-extending the diaphragm spring. But it got to the point where I needed to adjust the floater stops in-situ with the pedal fully depressed in order for it to release properly, and even then it was just borderline.

Eventually had to change the clutch though but I got about 4-5 years out of it and it held far more power than it was rated for, and even when I did change, it was because it eventually started slipping.

So yes you do look like you have plenty of slave travel, but you need to be viewing how each disc is getting released...or in this case not.
Assuming you've installed them the correct way around and they arent fouling each other or something silly.

belgiquebasterd

How did you adjust the floater plate? Maybe I messed up there, I turned up the stops until they were barely touching and then turned it another flat to get some preload.

stevieturbo

As said...I adjusted it with the pedal fully depressed until both plates were released. Through the starter hole in the bellhousing ( Quicktime...so luckily more room than stock BH )

Adjusting as per their instructions, one disc was always clamped tight. But again, the clutch was a few years old at this stage. It had worked fine for the first years as it was supplied from ACT.

It is a ****** to adjust in-situ like this....but still easier than pulling everything apart. Although if you've an OEM BH, I'd say it might be impossible without cutting some sort of access window.

Darth_V8r

iTrader: (4)

What gap did you end up with? My measurements and shims were such that the gap between fully compressed slave and pp fingers was 0.105".

It seems to me that I've read in other threads about the QT housing requiring a lot of shimming. Not trying to second guess, but it's pulling at some cobwebs.

stevieturbo

105 is way too small and leaves almost no room for wear. But all that would do is lead to premature slippage.

Can't see how it would have any relevance to this problem

Darth_V8r

iTrader: (4)

it would have relevance if the gap in question for the OP was in the 0.300 range. i provided my gap for reference. Ive always seen 0.120" as the gap setting.

stevieturbo

The only problem with a gap that is too large...requiring the slave to extend further, is the risk of it popping the seal.

That hasnt happened here. Slave travel will be the same regardless of the initial gap on first installation. Slave travel is dictated by "leverage" whether that's pedal/hydraulics.
And the video shows slave travel seems to be ample, although it is very difficult to measure. But given it's a twin he needs to check it as I described to see if both discs are clamped, or it is just a single disc that is clamped through the floater needing adjusted.

If both are clamped, then there could be a slave travel issue ( or clutch cover issue )

Darth_V8r

iTrader: (4)

Ten four. I was hoping to identify a simple solution. I do realize the .300" gap was too large. That was really the point I was trying to make and doing quite poorly apparently. All I was suggesting was that the gap, while measured, might be larger than ideal, resulting in failure to completely release. but what you're saying is that it isn't that simple in this case.

stevieturbo

The gap has nothing to do with whether it will release or not....simply because the hydraulic system will always take up any slack and in normal use the release bearing/slave will always be in light contact with the fingers.

So it's slave travel...ie leverage that operates the fingers. There isnt the obvious pivot/lever as with an older style slave, but it's all same principals.

The only risk with a large initial gap...is simply over extending the slave, which in these cases would be obvious as it will blow the seal out and **** all will work lol

But he needs to establish exactly which parts are not releasing.

belgiquebasterd

Tip of the day this one!! Cut the hole and immediately saw that the disc towards the transmission wasn't disegnaging. Turned out that the splines on the input shaft were too short and the clutch discs did not have enough room on the splines to disengage. During original installation I had about 1mm play but didn't take into account that things move around a little bit, this is probably also the cause of the first discs burning up.

Ground down the hub of one of the discs and now have plenty of play on the input shaft.

Thanks for the help and tips!!

stevieturbo

I meant drill a small hole to fit a USB bore camera through lol

ALthough obviously that hole will not allow you to adjust the floater stops in-situ very easily.

At the loss of some structural strength from the housing ( doubt it would ever be a concern, but I'm sure it's lost any SFI rating now )

Although I think they offer some BH's with a bolt on window ?

stevieturbo

Which input shaft are you using ?

I think my T56, the spline section is larger than the shaft, so the disc could literally fall off the end ?

Magnums etc use a larger shaft, where this may not be able to happen, and as you've experienced could jam up ?