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Tips
Tips

the clutch pin??

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Adrio

Jedi Knight
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My TR4A clutch started acting up last night. I am now wondering if I have the dreaded clutch pin broken. Can anyone tell me what symptoms I would see/feel if the pin that holds the throw out bearing fork to the cross shaft were to break.

What I have happening is some times it seems like my clutch is not working fully. As in I am at a stop and it will not let me move the shifter into 1st or reverse (without grinding a lot of coffee). But other time it works just fine.

I am at work and over luch I have been thinking about it. I realized I should check the fluid level before I panic, but I am worried I have to pull that tranny a third time in 1000 miles. The joys of a shake down after a five year project.
 
The first thing I would check is for air in the line. Clutches can be a real pig to bleed. Bleed it 'til you can't bleed it no more, then do it again.
 
Could be... my understanding is that the symptoms of the dreaded (always dreaded) clutch fork pin breaking can vary depending perhaps on whether the break is jagged enough that it catches and still gives some movement.

There isn't much difference (in terms of TOB movement) between 'works fine' and 'grinds for 1st and reverse'.

Certainly look at the movement of the slave & arm to verify you're getting decent (about 5/8") action there before taking the plunge again. Guess you know to install a cross-ways Grade 8 1/4" bolt with locking nut once you have it out... whether the pin is broken or not.
 
Tell me more about this grade 8 bolt. Where should that go?
 
[ QUOTE ]
Tell me more about this grade 8 bolt. Where should that go?

[/ QUOTE ]

It would go through the fork and shaft in a hole you drill from front to back - in the middle of the fork there may or may not be a flat circle, about 3/4 inch diameter (at the back, I think). Drill through the middle of that and you are in the right area.

Just a word of warning, I (foolishly) drilled using a 1/4 inch drill bit, and couldn't then find a 1/4 inch bolt that was a snug fit - they were all too sloppy for my liking. I didn't want to drill a bigger hole, so I went to Fastenal and picked up a pack of roll pins (1/4 diam x 1.1/4 length) which fit right, as they are a bit oversize anyway, so the 1/4 inch hole was still a tight fit. If you want a couple of roll pins, by the way, PM me your address and I'll put a few in the post - Fastenal only sells them in bags of 50! The roll pin isn't the best solution, I don't think, but it seems to work, and I have never read of a failure with any kind of backup to the taper pin (no doubt someone will have a horror story, though!)

If you decide to go for the bolt option, I found that a 2 inch long bolt gave the right length of thread (so the threads aren't wearing away at the hole in use) though you will then have the fun job of cutting 1/3 inch or so off the end of a grade 8 bolt...

I hope that some of this is helpful. Let me know if you would like the roll pins. (same goes for anyone else reading this!)
Alistair
 
Thanks Don. I am curious about the raised rear end though. The bleed nipple is at the front of the slave, so why do I want that lowered? I would have thought I wanted it high.

I did try to bleed it with a vacum pump and it seemed like I got a lot of air (more then could posibly be in there) so much so that it never stopped. I will have to try again the od fashion way once I have my wife or kids in the right frame of mind to sit there and push on the clutch.
 
Something I read somewhere which helps if you don't have a helper for bleeding is to remove the slave cylinder at the mountings, let it hang almost vertical (with the nipple slightly higher than the hose inlet, if that makes sense), open the bleed nipple and then push the push rod into the ground (or a block of wood, depending how high the car is). I did this after my wife had been kind enough to help bleed until we thought there could not possibly be any more air in the system, and sure enough I got a few air bubbles out. It gave slightly more travel (barely measurable) but I still had to pull the gearbox because my pin was broken.

Hope that helps
Alistair
 
Thanks Bash. When you say the pin was broken how 'obvious' was it. In my case now that I have tried to bleed it once, I took it for a drive and out of the 100 or so times I stoped and tried to put it in gear it only once gave me a problem going into first. And in that case it did not go at all, but if I pumped the clutch twice it went in. I really want to be sure before I pull that tranny again (there are so many other things I need to do on the car that I would rather spend the time on - like the top!)
 
Hi Adrio

It wasn't obvious to me that the pin was broken, since the operating lever seemed to be "solid". Actually even after pulling the gearbox I didn't think the pin was broken - the shaft seemed to be solidly attached to the fork. I decided to replace the pin as all the advice says to do so, and only when it came out was it clear that it was broken. I drove the car only a very short distance before I started work on it, and the clutch seemed to work fine, but once I disturbed things by rebuilding the hydraulics I found no clutch engagement - though from a few tests (pushing in gear etc) it seemed that the release bearing was almost moving enough to release the friction plate.

The real giveaway (which I tried to deny to myself) was the push rod in the slave cylinder, which had been lengthened by 2+ inches. Given that the gearbox couldn't have moved 2 inches, there really was no logical explanation for the long push rod other than a broken pin. If you want the long rod to try, let me know and I'll send it to you! It looked like it had been working for a while before the car was parked up - might get you through the rest of the summer?

Alistair
 
Thanks Alister,

Given it drives OK now but I am not confident in it, I will order me up a new pin to have on hand. I will try your push on the ground test one night to see if things change but I suspect a tear down and new pin (plus cross bolt) are in my future.
 
Adrio - As you are sitting in neutral, don't try to put the gear-stick into first. Put it into the 2nd gear gate. Then flick it forward into the 1st gear gate. This "synchronizes" the 1st gear speed. It should go in as smooth as silk. I don't know how many recent TR2 - TR3A owners I have told, and after they try it, they smile with amazement. Let's hope you try it and that you are amazed.

Let us know what you discover.
 
Don,

Thanks for the tip, but unfortunatly I have been doing that in my TR3 for 25 years and it has become a habbit that I do with all my cars (even the one made two years ago). In this case though even doing that I get the inability to go into first one time in many now.

I agree with you on this point. I too have told several owners about the 'trick'. In fact I don't see the great need to go through the trouble of changing tranny to get a full synchro box unless you are going to have to remove the old one anyhow. If you recall last year I opted for an overdrive box without synchro over a non overdrive box with synchro.

If only I had x-ray vision and could tell without a doubt the status of my clutch pin without taking the box off the car.
 
Well I tried everything before I had to pull the tranny and it paid off (so far). As best I can tell when I assembled the car I may not have tightened the jam nut all the way because there was about 3/4 inch of play on the slave push rod. I readjusdted the push rod to speck and it seems to work fine now. My hope is that is all it was. The test drive was a couple of hours and tons of start and stops. The car ran well enough that I was able to convince my wife to drive it for the first time (other then the first day it was on the road two years ago, and it ran so terribly that she swore she would never drive it again). The joy of a shake down after a frame off restore I guess.
 
Good for you... if it seems okay for now it should be able to stay that way. If it was a broken pin you would have never got that result with just an adjustment at the slave.
 
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