Topic: New MC Clutch Slipping

[dtc81]

1999 4runner 5VZ-FE 4x4 with 212k. Stock engine, gearing, and trans, 33" tires.

This is my 3rd Marlin 1200lb clutch kit install between 2 different 3rd Gen 4Runners. The average lifespan of these for me has been ~100k miles. Nothing but awesome things to say about the kit MC has put together. A year ago I swapped in a "new" transmission because the original was getting a terrible bearing whine. I had a known good trans in a parts truck, so I swapped that in as well. I replaced clutch kit and related bearings with a trail gear kit because the MC was backordered. I used a new flywheel purchased from MC. Fast forward 10k miles, the clutch started slipping BAD. Almost impossible to drive daily. I thought maybe the TG clutch kit wasn't up to snuff so I replaced it with the Marlin kit this weekend.

The clutch still slips a little under heavy load or when short shifted. I always install following my factory service manual and set the clutch pedal height and throw according to the manual.

Is it possible the slave cylinder is not letting the clutch fully engage? A friend told me to unbolt the slave and start the truck in gear and rev match it up to third gear to see if it still slips. That would rule out the slave. I haven't tried this yet, but figured I would try to get some ideas.

Thanks!

[gnob]

If you are immediately having an issue with a new clutch id suspect the slave(maybe) or the TO is hanging on the hub.


Or you suck at clutch driving. (you should get well over 100k on a stock clutch/rig)

[emsvitil]

Push the slave cylinder rod into the slave cylinder.

You should get a bunch of free play at the rod.   

Report back.

[dtc81 [OP]]

If you are immediately having an issue with a new clutch id suspect the slave(maybe) or the TO is hanging on the hub.


Or you suck at clutch driving. (you should get well over 100k on a stock clutch/rig)

It’s the same issue as before installing new clutch. I may have misdiagnosed a bad clutch as a problem with the slave. I generally do get a long service life on them. Previous clutches have just been changed as preventative maintenance while other non clutch related issues were being addressed and clutch was accessible.


Sent from my iPhone using Tapatalk

[dtc81 [OP]]

Push the slave cylinder rod into the slave cylinder.

You should get a bunch of free play at the rod.   

Report back.

Thanks, will do. I’ll be in the shop tomorrow with some free time.


Sent from my iPhone using Tapatalk

[Gnarly4X]

I’m having trouble with this issue.

A quality clutch disc, in normal driving AND frequent 4-wheeling, should easily go 100K miles.   A clutch disc slipping at 10K miles obviously indicates a failure somewhere.  If it isn’t contaminated with oil – either from the rear main seal or the input shaft seal on the housing  - then it’s a style of driving (very heavy clutch feathering when engaging the clutch) or the clutch pedal adjustment is way off.  I can’t imagine the slave cylinder is pressurized to the point that it’s pushing against the clutch fork with enough force to disengage the clutch disc without pressing down the clutch pedal.

Have you completely bled the clutch master cylinder and the slave cylinder?  The slave cylinder only has a very small movement distance in order to release the clutch disc when the pedal is pressed.

If the clutch disc is not fully disengaging, you would know it during shifting.

How much free-play is in the clutch pedal?  Where in the clutch pedal does the clutch engage and disengage?

I’m not sure that you can install a clutch disc in that vehicle backwards?

Gnarls.

[Pat]

Silly question,  but did you put the disc in the right direction?  If this is done they normally slip right from the get go..

Also any issue with the hydraulic system will make a clutch that will not fully disengage.  So that is not you issue..

[dtc81 [OP]]

Silly question,  but did you put the disc in the right direction?  If this is done they normally slip right from the get go..

Also any issue with the hydraulic system will make a clutch that will not fully disengage.  So that is not you issue..

I installed it per the service manual, and directions MC posts on their site that call out the direction for my vehicle.


Sent from my iPhone using Tapatalk

[dtc81 [OP]]

I’m having trouble with this issue.

A quality clutch disc, in normal driving AND frequent 4-wheeling, should easily go 100K miles.   A clutch disc slipping at 10K miles obviously indicates a failure somewhere.  If it isn’t contaminated with oil – either from the rear main seal or the input shaft seal on the housing  - then it’s a style of driving (very heavy clutch feathering when engaging the clutch) or the clutch pedal adjustment is way off.  I can’t imagine the slave cylinder is pressurized to the point that it’s pushing against the clutch fork with enough force to disengage the clutch disc without pressing down the clutch pedal.

Have you completely bled the clutch master cylinder and the slave cylinder?  The slave cylinder only has a very small movement distance in order to release the clutch disc when the pedal is pressed.

If the clutch disc is not fully disengaging, you would know it during shifting.

How much free-play is in the clutch pedal?  Where in the clutch pedal does the clutch engage and disengage?

I’m not sure that you can install a clutch disc in that vehicle backwards?

Gnarls.

I couldn’t agree more. My driving habits have been the same over countless manual Toyota’s, and I’ve never had this issue until recently. I have about 3/8” of free play in the pedal, and about 1” of stroke until resistance is felt. The pedal height is set at 6” from the actual floorpan. The truck shifts fine and doesn’t feel like the clutch is staying slightly engaged. I should have time to re bleed the system tonight, so we can take that out of the equation. Attached is a photo of the flywheel in the condition it was in when I first exposed it. Rear main seal, and input shaft seal were replaced 10k miles ago.

Thanks for the help.


Sent from my iPhone using Tapatalk

[dtc81 [OP]]

Bled the slave, loosened up the pushrod a little to give it some more free play. No difference, still slips.


Sent from my iPhone using Tapatalk

[Gnarly4X]

Hmmmm......

Typically a slipping clutch will smell and once the flywheel is inspected, it usually has hot spots on the surface.

When does it slip?

Gnarls.

[dtc81 [OP]]

Sometimes starting in 1st, but generally if I short shift or try to pull a higher gear at lower RPM. Highway cruising in 5th if I roll on the throttle fast it will slip sometimes too.

These instances were MUCH worse with the previous clutch than the newly installed one. But it’s still doing it.

I’m tempted to pull it back apart and have the flywheel machined or install a new one


Sent from my iPhone using Tapatalk

[79coyotefrg]

I couldn’t agree more. My driving habits have been the same over countless manual Toyota’s, and I’ve never had this issue until recently. I have about 3/8” of free play in the pedal, and about 1” of stroke until resistance is felt. The pedal height is set at 6” from the actual floorpan. The truck shifts fine and doesn’t feel like the clutch is staying slightly engaged. I should have time to re bleed the system tonight, so we can take that out of the equation. Attached is a photo of the flywheel in the condition it was in when I first exposed it. Rear main seal, and input shaft seal were replaced 10k miles ago.

Thanks for the help.


Sent from my iPhone using Tapatalk

she's been slipping but not bad.  Adjust the slave push rod so that only maybe a  1/4 inch of play is there then make sure the pedal isnt adjusted so that it is tight at that point.  You want a new clutch to be a little difficult to get in gear the first couple times but have adequate free play when the pedal is at the top.
did you have your flywheel turned?  if so did you shim it that amount?  AND did you have it stepped .025"

[emsvitil]

Does it slip just after a shift or if it's been in gear for awhile?

I've noticed that the self-adjusting slave cylinders seem to take awhile to fully disengage after a shift.....

[dtc81 [OP]]

she's been slipping but not bad.  Adjust the slave push rod so that only maybe a  1/4 inch of play is there then make sure the pedal isnt adjusted so that it is tight at that point.  You want a new clutch to be a little difficult to get in gear the first couple times but have adequate free play when the pedal is at the top.
did you have your flywheel turned?  if so did you shim it that amount?  AND did you have it stepped .025"

Is there an adjustment for the slave pushrod? I thought the only adjustment point was at the pedal pushrod. The flywheel was not machined this time. It was a new MC flywheel 10k miles ago

I do notice that the slave pushrod pushes just slightly on the fork. Not to the point where it moves it sitting static, but there’s 0 free play at the slave/fork interface.



Sent from my iPhone using Tapatalk

[dtc81 [OP]]

Does it slip just after a shift or if it's been in gear for awhile?

I've noticed that the self-adjusting slave cylinders seem to take awhile to fully disengage after a shift.....

After it’s been in gear a while. I can make it do it any time by either lugging a gear or stabbing the throttle.


Sent from my iPhone using Tapatalk

[79coyotefrg]

Is there an adjustment for the slave pushrod? I thought the only adjustment point was at the pedal pushrod. The flywheel was not machined this time. It was a new MC flywheel 10k miles ago

I do notice that the slave pushrod pushes just slightly on the fork. Not to the point where it moves it sitting static, but there’s 0 free play at the slave/fork interface.



Sent from my iPhone using Tapatalk

well there is on my 1979 rig but perhaps not on your v6.  is it a straight pin?  maybe you could shorten it maybe 1/8 inch

[79coyotefrg]

I see it isnt adjustable on yours so before you modify your slave pin/rod adjust the Master cylinder rod
I am 99% sure you are not fully releasing the clutch even when the foot is off the pedal.

[emsvitil]

If you can shove the slave rod back into the slave cylinder temporarily giving you a bunch of free play at the fork, you don't need to change the rod length.

The self-adjusting slaves work by not fully retracting the rod into the slave cylinder.    The clutch diaphragm springs push against the throwout bearing and clutch slave.   Then a little bit of runout and vibration gives you a teeny tiny amount of free play at the clutch diaphragm.

Unlike the older adjustable rods and spring where the adjustment was made with the rod fully bottomed out in the slave cylinder.


The only other thing I can think of at the moment is a clogged compensating port on the master cylinder.

last paragraph:  http://4mechtech.blogspot.com/2014/10/master-cylinder.html

[emsvitil]

Not fully releasing would do the same thing as a clogged compensating port.

[79coyotefrg]

After it’s been in gear a while. I can make it do it any time by either lugging a gear or stabbing the throttle.


Sent from my iPhone using Tapatalk

I can idle along in first gear on a gravel road and with my left foot outside on the slider so people can see my foot is not manipulating the clutch and stomp the go pedal hard and send rooster tails into the air.   It weighs 4400 pounds and those are 106 pound PtBull Rocker radials.   Marlin 1200 clutch installed in 2002 and a very modified 22R.

[79coyotefrg]

got to get some winks,  be back later

[dtc81 [OP]]

I can idle along in first gear on a gravel road and with my left foot outside on the slider so people can see my foot is not manipulating the clutch and stomp the go pedal hard and send rooster tails into the air.   It weighs 4400 pounds and those are 106 pound PtBull Rocker radials.   Marlin 1200 clutch installed in 2002 and a very modified 22R.

That’s why I’m so confused. I’ve NEVER had a problem with clutch slip before and this is way more clutch than this truck needs


Sent from my iPhone using Tapatalk

[Gnarly4X]

So you have a brand new clutch and pressure plate, and flywheel.  What are the part numbers?  Are you sure they are the right parts?

One way to eliminate the hydraulics factor is simply remove the slave cylinder pin so there’s no pressure on the clutch fork.  Move the clutch fork back and forth to make sure it has free play - moving the throw-out bearing on the input shaft housing freely.  Start the truck in gear and drive it, shifting with RPM/gear meshing and see if the clutch slips.

Then you know it is mechanical and is in the clutch disc, pressure plate, or flywheel.

Once a clutch disc starts slipping, the flywheel, pressure plate, clutch disc can get "glazed" and probably will continue to slip until cause is fixed.

Gnarls.

[dtc81 [OP]]

So you have a brand new clutch and pressure plate, and flywheel.  What are the part numbers?  Are you sure they are the right parts?

One way to eliminate the hydraulics factor is simply remove the slave cylinder pin so there’s no pressure on the clutch fork.  Move the clutch fork back and forth to make sure it has free play - moving the throw-out bearing on the input shaft housing freely.  Start the truck in gear and drive it, shifting with RPM/gear meshing and see if the clutch slips.

Then you know it is mechanical and is in the clutch disc, pressure plate, or flywheel.

Gnarls.

Thanks Gnarls, I pulled the slave quick last night and the fork does have free play. A friend recommended that I do what you just said and drive it with the slave unhooked and just rev match to see if it slips. I’ll try that tonight.

MCCL-129 clutch kit
MCCL-222A flywheel


Sent from my iPhone using Tapatalk

[Gnarly4X]

dtc81...

You have a real mind-bender there!!!?? 

Gnarls. 

[dtc81 [OP]]

dtc81...

You have a real mind-bender there!!!?? 

Gnarls. 

I sure do. Bringing it to a friend who is a Toyota master tech tonight so he can get a feel for it and hopefully some insight. I’ll report back


Sent from my iPhone using Tapatalk

[dtc81 [OP]]

Didn’t make it to my friends’ to have him help, but did pull the slave cylinder to the side and drove the truck just rev-matching. No difference. Still slips.

The only part of the equation that is “old” is the flywheel. With 10k miles on it and less than a year, I wonder if it’s possible it wasn’t correctly machined from the factory? It’s a stretch


Sent from my iPhone using Tapatalk

[OOPS]

Anytime you put a new clutch you should have the flywheel re-surfaced, also make sure it have the right step machined in it, I cannot remember what size step Marlin machined into mine!!

[Gnarly4X]

MCCL-129 clutch kit
MCCL-222A flywheel

dtc81.... is it possible that the clutch kit and/or the flywheel that you received from MC is NOT the correct parts for your vehicle?

Perhaps they shipped a wrong part(s) by mistake? 

Gnarls.