Clutch Engagement Variation

[SLC]

Gentlemen,
Upon removal and re-installation of my transaxle I have found the clutch engagement point to be significantly different. All is bled in every way possible so, I doubt air entrapment as the cause.

My next logical area of probable cause is that one or more of the clutch plates may be installed backwards (?)

So my questions are -
Anyone have cause and effect on incorrect clutch disc install?
Has anyone had clutch discs installed incorrectly and found engagement point changed?
Is the center boss of the clutch disc offset?
Does anyone have pictures of both sides of the clutch plates?

The goal here is to try and determine if I HAVE TO pull the transaxle and have a look to confirm the correct clutch disc orientation. :facepalm:

Thank you very much in advance for your input.

 

[Xcentric]

Where is it engaging now and where did it engage before? The engagement point gets higher as the clutch wears. I'd expect it to engage lower with new clutch.

The flywheel side of the loose plate says "FLYWHEEL SIDE." Unless you took the assembly apart, only one plate is loose.

Flywheel side:







Pressure plate side:







Don't know if you can see it, but it says "FLYWHEEL SIDE" between the two top springs, opposite the "7."

The flywheel side center section is almost flush with the friction surface. The pressure plate side is raised about 1/2" above the friction surface. So yes, offset.

I don't know if it can be installed backwards.

 

[nota4re]

The engagement point gets higher as the clutch wears. I'd expect it to engage lower with new clutch.

Actually, just like our hydraulic brakes (where the pedal engagement point in independent of pad thickness), the same is true of our clutch. The should be no change in engagement point based on a new or used clutch - or as wear occurs.

To the op - we have installed dozens of clutches and have routinely found that the system is easy to bleed. If you have made just reasonable attempts at bleeding and the clutch doesn't feel right, you probably need to remove the transaxle again to determine what is wrong.

 

[fjpikul]

There are two spots to bleed the clutch. First up high on the firewall and second one low on right rear side.

 

[Xcentric]

The should be no change in engagement point based on a new or used clutch - or as wear occurs.

Well, there is. If not from clutch wear, then what?

 

[NorthwoodGT]

I don't think you can really install 1 of the clutch discs backwards. I think you would have seen it right away.
has to be air in the line somewhere. you can bleed at the bulkhead connection and at the trans both. jmo
PS: good pics Gary

 

[nota4re]

The "hardest" part about bleeding the clutch line is the very small reservoir - which is all too easy to run low during the bleed process. When we do it, we try to do it with 3 people. One inside the car, one at the bleed nipple, and a third making sure to keep the reservoir topped off. We SELDOM have ever had to use the bleed nipple up on the firewall. Regardless of appearance, we ALWAYS replace the hydraulic throwout bearing with each clutch job that we have done. To your point, it would be no joy to have to go back in there.

 

[NorthwoodGT]

The "hardest" part about bleeding the clutch line is the very small reservoir - which is all too easy to run low during the bleed process. When we do it, we try to do it with 3 people. One inside the car, one at the bleed nipple, and a third making sure to keep the reservoir topped off. We SELDOM have ever had to use the bleed nipple up on the firewall. Regardless of appearance, we ALWAYS replace the hydraulic throwout bearing with each clutch job that we have done. To your point, it would be no joy to have to go back in there.

+1 great procedure for sure

 

[TO AWSUM]

I use the MOTIVE pressure bleeder to change my clutch fluid so you only need one person and never fear running out of fluid. Just choose and install the appropriate adapter onto the master cylinder, the hose, the tank and put some fluid in the tank. Pump up the MOTIVE tank pressure and then open the bleed valves on the rear firewall and the tranny. Super easy. I use this same MOTIVE system to bleed the brakes. Never had a problem.

Also remember there is a specific procedure in the Maintenance Manual that needs to be followed of pumping the clutch pedal a few times after the bleeding is completed to get the clutch pedal to respond correctly.

I've never allowed air to get into my clutch lines, so like nota4re, I don't open the firewall bleed valve and only bleed using the tranny bleed valve. In your case since you changed your clutch and probably got air in the lines, you may have to bleed at both points.

 

[nota4re]

Also remember there is a specific procedure in the Maintenance Manual

I doubt it is what is described in the manual, but the technique for the person in the car pretty much requires that they are not wearing shoes. During the bleed process, once the clutch pedal is depressed, it is often quite happy to stay down on the floor. It takes a small amount of "toe agility" to coax it back up again!

 

[SLC]

Excellent pictures Xcentric! That was just what I needed.
I appreciate everyone who took the time to respond, thank you.

My feeling is that dyslexia may have reared its ugly head and I installed the 'loose' disc backwards. Cwap.

Currently the engagement point is about 3/8" off the stop as you release foot pressure from the pedal, I'd say I have 1" of additional travel before the clutch is fully engaged and full "bite" is attained.

 

[TO AWSUM]

Funny nota4re. Here's the procedure I was referring to accomplishing after the bleeding has been completed:

6. Slowly pump the clutch pedal several times to verify there is no fluid leakage.
Depress and release the clutch pedal 5 short cycles, and 2 full-travel cycles. Repeat both cycles 10 times.

 

[Xcentric]

Currently the engagement point is about 3/8" off the stop as you release foot pressure from the pedal, I'd say I have 1" of additional travel before the clutch is fully engaged and full "bite" is attained.

Yeah, I'd be concerned that the clutch may not be releasing 100%. And shifting can't be fun if you have to mat the pedal.

Conversely, mine grabs almost at the top with 31k miles. It engaged right about halfway when new.

It doesn't sound like a bleed problem, although you may be understandably reluctant to get it hot enough to see if behavior changes. Best you can do before tearing it apart again is double/triple check that all air is out.

 

[nota4re]

We had an ultra-low mileage (<200 miles) Heritage in here not too long ago which was owned by a collector. He asked us to change all of the fluids, install new tires, new oil pump belt, replace the battery, get the car smogged, and generally get the car ready to be driven. Fine, no problem. "Oh, by the way, the clutch needs a little bit of adjustment too as it doesn't seem to disengage properly." Um, ok, we'll have a look.

After taking care of the straightforward items we began investigating this "clutch adjustment issue" on an otherwise pristine, ultra-low mile Heritage. We bled the be-jabbers out of that car and were left scratching our heads when it didn't seem to disengage. You could start the car just fine in neutral.... but you sure as crap couldn't put it into any gear. What the heck? Finally started a closer inspection of the bell housing and saw evidence of either a rat's nest or clutch material. Finally made the decision to pull the transaxle off and take a look. "Holy shredded clutch, Batman!" It was, by far the worst clutch shredding I had ever seen! I guess I have little doubts of WHAT happened, I just don't know the WHO. Someone revved that beast up, inadvertently placed the car in 3rd instead of 1st and dropped that clutch and let her rip. Motor revs, nice smell of burning..... something..... only to discover that it wasn't really the tires that were spinning. Anyway, we installed a new clutch (and slave) and the car was good to go - although the due bill was a tad higher than the original estimate!

 

[mmlcobra]

I believe that has happened more then once!

 

[PeteK]

A couple of my observations:

1. Looking at the pics Xcentric posted, the clutch disc sticks out further on the pressure plate side than the flywheel side, so I don't think you can assemble it backwards. It should have been pretty obvious when putting it on. So, take a closer look at the bleeding procedure. Does anyone have a clutch pack handy to see if you can put the disc on backwards, or whether it interferes?

2. My clutch now has close to 60Kmi on it, and it engages about the same as it did when it had 25Kmi on it. The hydraulic slave cylinder takes up the slack, so no adjustments are needed, and the clutch throw and engagement zone "should" stay the same. However, on another car with a hydraulic clutch, I noticed the clutch engagement changes as the clutch wears, so it's not a hard and fast rule. However, the shop manual says it's self-adjusting.

3. Accidentally starting in 3rd. Yeah I've done that a couple times too. But I tend to be easy on clutches when getting going from a stop. I don't like to rev the engine and drop the clutch. As a mechanical engineer, I just wince when I think about what that does to the the whole drivetrain. So, on the occasions when I've accidentally started in 3rd, I ended up lugging the engine, rather than burning the clutch. I have not worn out a clutch in any car I've owned, although I have replaced the clutch disc while I was in there because of a bad throwout bearing.

 

[BIGFOOT]

+1 great procedure for sure

+2

 

[SLC]

Just wanted to drop a note on this;
As I suspected the disc was in backwards and the center metal ''boss'' was making contact with the center area of the flywheel. The pedal effect was that the clutch stack essentially was thicker than normal and the fiber plate was flexing as pressure plate was engaging. I imagine if pushed hard enough the clutch would have slipped and caused those alarm bells to ring as well, but I wasn't going to push anything like that since I had already suspected foul play (on my part as it were). The flex of the clutch disc caused the pedal throw to be longer than normal to achieve disengagement. Although, I must say it did make for some nice long engagement progression

All is corrected now and things are normal.

Thanks again for all the input.

 

[Xcentric]

Glad you got it sorted and thanks for closing this out. Often, guys don't bother to post resolutions to problems.

Interesting to know that the disc can be installed backwards.

 

[PeteK]

Yes, thanks for posting the resolution.