I have my gearbox out!

[Kneeslider]

Well, here we go, I guess.

 

First of all, I would like to appologise for not being around here much lately, and if clutch issues have been recently discussed, then my appologies.

 

I have a problem with my clutch in that the lever on the end of the gearbox would travel back and forth, but the cluch remained resolutely engaged (and stuck! The car has not run in >10 years!) and when the arm was moved manually, there was a solid clonk noise, but no indication that a spring was being depressed at all.

 

So, after I had got the master and slave cylinders working, my attention came to removing the gearbox to have a look inside the bellhousing.  I found that there was a laycock clutch bolted to the flywheel (good news) but that someone previously had welded the clutch release fork to the spindle which passes through the bellhousing.  I also discovered that the shear pin which connects these two components has sheared in the classic 45deg fashion noted by Roger Williams in his restoration book.

 

Now, I have a bit of a problem. It would seem that the fork has been welded to the spindle in the wrong position and the shear pin was still lockwired in place! DOH!  And as a result of the welding I can't get the spindle out of the box.  Access is a bit limited to get an angle grinder in to grind off the welds, so it looks like my only option is to cut the spindle to get all the bits out, then attempt to recover as much of the fork as possible.

 

Unless of course, anyone has any bright ideas?

[marvmul]

You could weld the outside lever in a new position to compensate the wrong position of the fork, but I wonder if the weld between fork and shaft will last long.

Replacing the shaft and fork seems to be the most sensible solution?

Racetorations and other specialists sell an integrated hydraulic release bearing kit, it works without the cross shaft. It's rather expensive (some 350 pounds).

[Richard Crawley]

Cut the shaft with either a grinder or a hack saw, I had to! It’s not worth messing about with it both as will have to be replaced both in any case; It’s a while ago but I seem to remember the shaft wasn’t that expensive anyway. & don’t forget to lap in the new taper pin & change the cross shaft bushes while you’re at it; & use a good quality release bearing

[tim_trinda]

Have a look at this link, the 'nasty pin' problem is covered in some detail and there are also suggestions to make the thing more reliable without spending lots of money!!

 

========

Tim

[Kneeslider]

Well, after a while sitting and thinking about the problem, I attacked the welds carefully with an angle grinder, but after putting  a couple of bars on the fork and the clutch release arm and heaving mightily, the thing wouldn't free off.  I was concerned that I couldn't quite get the grinder at all of the weld, and there  wasn't even enough space to get a file in, so the only remaining option was the cut through the shaft.

 

After removing the shaft, I found that I could grind away the remainder of the weld and then just had to remove the remains of the pin, surprisingly, I found that the heat from the welding process has sufficiently softened the pin to enable me to drill the pin and weaken it sufficiently so that after securing the fork in a vice I was able to drift the shaft out with a (very) large hammer.    The old pin is now in 3 pieces, but it looks as though the fork is re usable.  There is little wear on the shaft bearings, so they will be fine, but I will replace the fork pivot pins before putting a new clutch in.  Thanks again for the links.  Suffice it to say that I will also be drilling the fork to fit  a secondary bolt and nyloc nut.

[Tom Fremont]

I haven't had problems with the notorious throw-out fork pin in many years and probably close to 100,000 miles of driving on my TR250s. Aside from carefully aligning the gearbox with the engine, the only extra measure taken was to ensure there was no " rock " of the fork on the shaft with the pin installed. To eliminate this it was sometimes necessary to round off the shoulders of the square head where it touched the shaft so as to allow it to go far enough in to jam its taper tight into the shaft. Hardened pins have been available over the years, but one school of thought says these cause other problems, and supposedly the standard pin is up to the job ( and has been for me! ). ::

[Richard Crawley]

but it looks as though the fork is re usable.  There is little wear on the shaft bearings, so they will be fine,

You are obviously going to need a new shaft so why not fit a new fork as well, I think it’s a false economy not to. Do you really want to chance having to remove that great lump of a box again if it don’t work properly? The DU shaft bushes also cost next to nothing & are so easy to change, you may as well replace these as well, even if they look OK! Personally, if I had to haul my box out, I would take the opportunity to replace the whole clutch unit & release bearing as well, particularly if the existing unit had been in there for more than 20K miles

[Andy Moltu]

The reputation for the taper pin shearing probably reflect a large number of substandard pins. The originals wre probably fine as are the new, higher spec ones - it's just the after market standard ones which seem to be the problem.

[Richard Crawley]

The originals wre probably fine as are the new, higher spec ones - it's just the after market standard ones which seem to be the problem.

This is a good point to remember when sourcing & always go for the (so called) uprated pin.