41 replies to this topic

[GraemeC]

Two gaskets will probably give you far too much clearance. IIRC they are around 0.018" thick and you are looking for 0.005" clearance (from memory 0 figures should be checked!!)

So you may currently be 0.003" undersize so another 0.018" gasket would leave you with 0.015" clearance - ie far too much!!

I think there is a range of around 0.009" differences in the shims.

[Sprocket]

Please tell me you have measured the idler end float and that it is within tollerance. As suggested, gaskets vary in thickness and the only real way to fix a tight or loose clearance is to fit the correct size thrust washers. You can buy a kit that should get the tollerence within limits.

[Clubber Lang]

I have put the original idler gear back in along with the replacement primary gear and put gasket sealer on both sides of the gasket. I have fitted the transfer cover and threadlocked the bolts tightening them gently as my torque wrench doesn't have a setting low enough for these bolts. I have tightened them very carefully and checked gear movement as i have gone. Having checked the first gasket i have come to the conclusion that i may have overtightened it first time (didn't know the tolerance on the idler was so tight) so i have nipped the bolts up as much as i dare. There does seam slight resistance but i can turn the primary gear by hand quite easily. It isn't as free as it was without the cover on but it is a lot better than when i took it all apart. My only worry now is that it may go tight when the engine warms up.
As for measuring end float on the idler gear, i wouldn't know how as you can pull it in and out and once the cover is on then you can't measure it at all (may have made myself sound a little dense here).
Shall i connect everything back up tommorow and give it a go or am i gonna regret it? regards Steve

P.S. I still don't FULLY understand how this was causing clutch/gear change problems i think i have worked out why but if anyone could explain is 'simple' terms feel free to enlighten me, cheers Guys

Edited by Clubber Lang, 23 September 2009 - 12:17 AM.

[Petes.one]

Not difficult to measure the idler end float if the gearbox is split from the block. Do a dry run assembly - fit the idler in place then the end housing onto the gearbox with the new gasket in place. Nip the bolts up to the correct torque readings, then the end float between the casing and the inner thrust washer/shim can be measured with a feeler gauge. Should be 0.10 to 0.18mm according to Haynes.

[Clubber Lang]

Thanks Pete, as i have been doing all this with the engine still in the car i'll give that a miss lol. Ive got it all back together now just connecting everything back up and get up and running tommorow maybe then we'll see. If its still the same its going to the breakers lol. Regards Steve

[Dan]

I suppose you could measure it with Plasti-gauge. It would be unconventional though. If you do, do it with the car in gear so the idler is locked and can't turn as you tighten the housing.

[Clubber Lang]

Hi Dan, what is a plastigauge?

[Dan]

Plastigauge is an engineering tool. It's used to measure clearances on blind, internal or otherwise inaccessible parts. It's a material similar to plasticine that is formed into very precisely controlled dimensions. You place a strip of it into the joint you are checking and close it up. Then very carefully open it again. The ribbon has now been squashed, you compare the width of the squashed strip to the markings on the pack and it shows what the clearance is. It's not normal to use it for this but it might work.

[Sherlock]

Plastigauge should work well in this situation, also what I usually do, with primary gear & seal removed, I can get my finger to the top of the primary gear & see if it will float back & forth, not very scientific, but I can tell whether it's more like .005" or .025". This is something I always do when replacing a clutch seal, just as a check that all is well. This problem interests me, because I can see from the replies that a lot of thought has gone into it, but I have never experienced anything like this due to changing a gasket. You can still try different shims using the plastigauge or my 'finger' method. Not wishing to complicate matters, but the only time I ever had a similar situation which was not clutch related, the flywheel had crept a little too far up the taper & nipped the 'C' washer which locates the outer primary gear thrust washer causing partial siezure of the primary gear on the crank.

[Clubber Lang]

Interesting. When i removed the flywheel (which had only been on for 10 miles) the nut although it hadn't moves was not that tight even though it had been torqued correctly. Then when i put the flywheel puller on the flywheel came off a little to easy for my liking. regards Steve

[Sherlock]

If the flywheel has contacted the 'C' washer you may see evidence of it in the recess in the back of the flywheel, if not, just to prove a point, plastigauge on the outer face of the 'C' washer, bolt the flywheel back on & see how much it has compressed. If compressed to nothing that could well be the problem. In fact you could use ordinary plasticene or blue tack because in this situation, you only need to know whether there is some clearance or none at all, measurements don't matter. If you suspect this as being a problem a small Dremel or similar grinder will take a couple of thou off the surface in the flywheel recess which faces the 'C' washer. Obviously I can't say that this is the problem, but if all else fails, it might be worth a look. Regarding your flywheel bolt not being as tight as you expected, check the surfaces of the tapers for burrs & creep-marks.

[Sprocket]

The flywheel will only contact the 'C' washer if the taper has been reground.

The loose fly wheel will be down to the taper not being seated correctly. I personaly tighten the flywheel bolt to the desired torque, then gently knock the center all the way roundwith a soft faced mallet, slacken the bolt then re tighten. I do this three times. You can see how much more the flywheel moves on the taper by how much further the bolt turns.

Checking idler clearance with the engine in the car has been touched on, however, how it is actualy done is to use a DTA through the opening where the primary gear seal fits, onto the outer edge of the idler gear, you can then see the end float. I have always found the gaskets in the Minispares kits to be overly thick which in this case is a good thing (if there is no end float to measure because it is tight, how do you know how much to adjust it by?). What you need then are some new thrust washers to correct the end float clearance.