TR6 Sticking TR6 Clutch

[Webb Sledge]

I recently put in a new B&B clutch, and have been having trouble with it when the car gets hot. Once the car warms up to normal temp, the clutch begins to kind of stick when released, like you're rolling your foot over small square pipes that don't want to roll. It's hard to describe. It will stick in different places and the release is just rough in general. I've replaced the master and slave cylinders, bled the system, the fork and TO are fine, and the clutch is installed properly. It engages and disengages just fine, it's just the inbetween that's rough. And it ONLY does this when the car is hot. When it's cold, the action is smooth and linear, like it should be. It's a mystery to me. Any suggestions?

 

[Dugger]

Welcome to my world.

I did the same change out this past summer and I have the same problem. When cold, the clutch operation is smooth as silk, but as soon as the system reaches operating temperature, the clutch doesn't seem to want to engage/disengage smoothly. It takes a full throw of the pedal to release the clutch - meaning clutch pedal against firewall! When cold, this is not necessary.
I am not sure what the cause is and I have no answers for you, but if you do find the problem please list it or contact me.

I installed new MC and Slave, replaced the nylon hose with braided SS, checked the movement (cold) approximately 9/16" (center hole, checked for hole wear at the pedal and the radius arm - all checked out fine. Now that winter is coming on, I will again pull the tranny to re-inspect everything that I did inside. I have driven the car this way since June and it appears to be getting a bit better which leads me to believe that there must be a binding situation between the front cover and the TO carrier (all new also) The original TO bearing carrier was bronze (and somewhat worn - ergo the change)but the new one (Moss) is steel with some type of protective coating. I removed the coating on the inside and polished the cover prior to assembly, but did not measure the clearance between. I will do that when I pull the tranny again. I coated the interface with a bit of white lithium high temperature grease hoping this would not degrade and find its way to the clutch plate.
Another possiblity that was mentioned to me was that the clutch plate may be spreading apart when reaching temperature, but there would be no way to verify that unless I develop some sort of xray vision.

Also, during the original install I opted to use a cross shaft from a TR4A with the grease fitting and the shorter bushings - two on each side, which seemed to to provide a "truer" fit. A new fork/shaft pin was installed and the TO pins in the fork were also replaced. Like I said earlier, everything was replaced for new with matching(or so I was told) parts.

I sure hope you find the source because I have scratched my head until I have no hair left.

 

[martx-5]

Maybe the clutch driven disc is binding on the splines of the tranmission input shaft.

 

[piman]

Hello Webb,

my guess is that it is to do with the clutch release bearing carrier sticking on the input shaft sleeve. To prove it get the car hot and operate the clutch relese lever by hand. (disconnect the push rod and use a short tube, for extra leverage, over the release arm. You should be able to feel if it is rough and also, proves if it is a hydraulic problem or not.
Mart, I don't believe this will make any difference as the centre plate doesn't really move on the splines when the clutch operates.

Alec

 

[trboost]

I agree with Alec. This kind of symtom is usually caused by the bearing carrier binding on the front end cover (out put sleeve ). Over time the front end cover develops slight ridges & a burr at the tip. The bearing carrier also wears & eggs. These components are rarley if ever replaced in a normal clutch service , so they can have many , many miles on them & are 30 years old.

Special attention should be paid to the end cover by using 400-600 sandpaper & dress the shaft . A light coating of a moly based grease should be applied. I have had great success with the Gunst bearing kit. It comes with a new bronze bearing carrier, which in itself is a great improvment over the steel one originaly used for this application. Bronze is a naturaly lubricating material that has excelent wear characteristics. The bearing itself is also a realy nice piece. This has made all clutch release problems a thing of the past, leaving you with a very smooth & almost lighter feel. It has become so popular that TRF sells it & BPNW has their own version.

On a side note, I had installed a "rebuilt" B&B pressure plate years ago & never had good clutch operation until I replaced it with a new unit. I'm not sure of the reason or what was incorrect in the rebuilt unit but I stick with new now.

P.S. Make sure the stop pins are in the carrier so it dosen't spin and the fork pins are replaced when serviced.

 

[Webb Sledge]

I'll use Alec's idea with the steel tube to work the lever by hand and see if that's it. Mitch, my B&B clutch and pressure plate are nearly new, only a year old, and that leads me to believe it's not a wear problem with the clutch unit. darn I hate pulling trannies.

 

[trboost]

Webb,
Nothing sucks more than doing the same thing twice (or even three times /ubbthreads/images/graemlins/cryin.gif ), ask me how I know. Right now I'm dealing with drive line vibration that I have had on & off for over a year. I have pulled my driveshaft at least 6 times, replace several U-joints, my diff twice & now I'm gonna pull it again to install a diff I'm rebuilding.
IT SUCKS. Oh, but the feeling when it's fixed is priceless !

Unfortunatlly it comes with the territory when you have a passion for old British cars. You will solve the problem , along with many other problems , and it will make those days when everything seems to work perfectly worth every hour under the car.

Pay attention to the parts I described, it's usually the cause of the problem you describe. Leveraging the clutch shaft arm should expose it but sometimes it starts after the output nose has heated up after running a while.

 

[Webb Sledge]

Would it be possible that a slightly bent input tranny shaft or a slightly bend throwout bearing could be cause my sticking clutch release? I recall that I had to use quite a bit of force to get the tranny to drop onto the engine, and I'm wondering if it wasn't maybe a little to much.... but hey, live and learn, right?

 

[trboost]

Webb,

I'm sure your a strong guy , but it takes alot to bend the shaft. Besides it would vibrate pretty badly at speed.

 

[SpannerMan]

I recall seeing a warning, probably in one of the manuals, to not let the transmission weight hang on the input shaft while you're putting it in. If you're working alone, I think it's pretty hard to avoid- I think mine was hanging, and I don't have any clutch disengagement issues. I did have the hanging up clutch when hot as you describe but it went away after I worked on it- I changed everything in there though - different transmission, new 3 piece clutch, front cover/TO bearing carrier, cross shaft+ bushings, release fork+ taper pin. I used white lithium grease on the input shaft splines and TO carrier. Good luck. Pete


[ QUOTE ]
Would it be possible that a slightly bent input tranny shaft or a slightly bend throwout bearing could be cause my sticking clutch release? I recall that I had to use quite a bit of force to get the tranny to drop onto the engine, and I'm wondering if it wasn't maybe a little to much.... but hey, live and learn, right?

[/ QUOTE ]

 

[71tr]

I know this is a continous topic with our cars but here are my thoughts. The clutch fork has two pins in the arms which actuate the throw out bearing. These pins wear at different rates and likely operate the fork in a non-symetrical fashion. I'll bet this causes the throw out bearing to bind on it's carrier. Heat from operation may aggravate this problem as the various parts expand at different rates.

I've torn down my tranny for rebuild and the pins in my fork are significantly different in their wear pattern. I'm replacing with a gunst throw out bearing. Interestingly the gunst TO bearing utilizes square inserts which ride on the fork arm pins to actuate. As previously stated the pins can be replaced or simply rotated to provide a fresh operating surface.

 

[Webb Sledge]

Hmm, that's a good thought 71tr, considering I haven't check those. I don't know how signifigant it is, but my clutch does not bind at all when the car is off, no matter how hot it is. If I were to sit in traffic all day and let the temp gauge get nearly into the red, I could shut the car off and the clutch would operate smoothly, in and out. Would you still suspect the pins in the fork?

 

[71tr]

Hmm, that is an interesting observation, no problems if the engine isn't turning. That implies to me that the throw out bearing is binding on its carrier due to the lateral forces of the spinning pressure plate. As the TO bearing engages the spinning pressure plate a sideload is transferred into the TO bearing and if there is play in the setup then it binds on the carrier. My theory anyway with two fixes; remove the TO bearing and sleeve from the carrier and champher the inside edge of the bearing sleeve, this might ease the tension between the two moving surfaces. Second is to address any play in the fork arm pins. Again, if they are worn unevenly then the bearing and sleeve can wobble on the carrier. This is one feature of the gunst TO bearing that I like, the square inserts which fit on these pins ride in a channel on the bearing sleeve thus not allowing excessive wobble. My 2cents.

 

[Webb Sledge]

Maybe its just a crappy TO. This is the second one it's had, and it started squeeling quietly withing 6 months.

 

[bkkiser]

The clutch is sticking due to the misalignment between the engine and the transmission. On the 6-cylinder Triumph engine two 3/8" bolts align the transmission to the engine. These bolts are located at about the 2:00 and 8:00 positions. These two bolts are difficult to install and people often use 5/16" bolts instead of the 3/8" bolts.

I've recently fixed a TR6 that had one of the two 3/8" bolts. The other bolt was a 5/16" bolt. By moving the transmission as little as 1/64" and installing the correct 3/8" bolt the problem was fixed.

NOTE: The 3/8" bolts I'm talking about are NOT the bolts for the starter. The starter bolts are also 3/8" but do not align the transmission to the engine.

For more info see the article "Laycock or Not to Laycock" on the "Tech Info" page on the Minnesota Triumphs web site. www.mntriumphs.org

 

[bkkiser]

Squealing throughout bearing.

A squealing TO bearing is usually due to the bearing NOT turning at the same speed as the pressure plate. The TO bearing MUST be in constant contact with the pressure plate and turning at the same speed as the pressure plate.

The stock bearing has a LIP seal that DOES NOT contact the inner race of the bearing. This reduces the torque required to turn the bearing and allows it to turn with the pressure plate.

"Heave Duty" aftermarket pressure plates (i.e. The Magic Clutch) have bearings a SEALED bearing with a lip seal in direct contact with the inner race of the bearing. The sealed bearing takes too much torque to turn and will not turn at the same speed as the pressure plate. Then when you step on the clutch, the bearing must increase in speed until it turns at the same speed as the pressure plate. The squealing is due to the differential speed between the pressure plate and the bearing.