How tight on the splines should the driven plate be?

[Waynebaby]

Hi All,

I'm changing the clutch on my Mk3 GT6 for the first time and, following the instructions that came with the Borg Beck 3 in 1 clutch kit, I've tried a trial fit of the driven plate onto the splines of the gearbox input shaft. To start with it wouldn't go onto the shaft at all and I began to think I had a miss-match of some kind until I found that the old driven plate was equally reluctant to mesh with the splines (only doing so after a lot of cursing and jiggling) The shoulders on the splines at the engine end of the shaft seem designed to encourage disengagement of the mesh rather than engagement.

I find that I can now get the new plate started on the splines but have to drive it up the shaft with a large socket. Hardly a sliding fit. All I can say is that it's not surprising that installing the gearbox in the car is so difficult if spline-engagement puts up this much of a fight with the gearbox on the bench!

My question is whether or not what I am experiencing is normal or if there is something amiss with the shaft or driven plate?

Any suggestions will be as usual, greatly appreciated.

Wayne

 

 

 

 

[Colin Lindsay]

The plate should be a straight slide-on fit; it has to be to move freely under pressure of the clutch pedal / cylinder. No way should it need hammered along the input shaft.

Silly question but are you sure it's the right clutch plate ie same number of splines as your GT6? Or: is it the original gearbox? Mine runs on a Dolomite 18/50 box and therefore needs the Dolomite plate, rather than the original GT6 version. 

Can you post a photograph of the splines?

I'll post one, unfortunately from a Herald box, but it will let you compare to a certain extent in case there's something glaringly obvious.

 

[Pete Lewis]

echo Colins reply,  definitely  must be free to float easy back and forth on the splines

the early has 10  cut splines the later have 18 and its a rolled formed spline , so very different

you could use a stone to fettle the spline and even the disc , for any burrs that have happend  if both disc are reluctant to slide then the shaft seems the common culprit.

but a rattling good fit is better than a tight one 

Pete

 

[Waynebaby]

Colin and Peter,

Thanks for your thoughts. I think it is the correct clutch for a GT6 (HK 8910) Both the new plate and the one that came off the car have 10 splines like the shaft and as far as I can measure with calipers the dimensions are identical. In the attached photos the new plate is on the right. Once I get the plate ~1 cm onto the shaft it frees up, so I'm assuming that that must be the normal operating range of the clutch in service. I'll try fettling the splines to see if that helps the plate onto the shaft..

The suitability of the new plate is now academic. When I got it onto the shaft I spun it to check for run-out. I'd got out my dial gauge but didn't need it as I could tell straight away that it has a run-out of 2-3mm. Another case of buy in haste on flea-bay and repent at your leisure - there's usually a reason why an item is so cheap isn't there but at ~half the price of the club shop it seemed like a good idea at the time. 

I'll see how I get on with the new plate and let you know.

Wayne

 

[dougbgt6]

"a rattling good fit is better than a tight one" 

Wrong web site again Pete!

[Gully]

If there's something wrong with what you've bought then return it - makes no difference whether something is cheap: faulty is faulty and your statutory rights apply. Irrespective of who owns Borg and Beck now (or then, if you bought old stock), there should be quality control. That's assuming you didn't damage the disc getting it over the tight spot on the shaft! ??

Gully

[Pete Lewis]

I will try to upload a cause effect of clutch failures but not from this silly tablet 

Clutches can easily suffer from poor handling  which disturbs the factory setting especally old stock thats been humped all round the country

Especially on recons where anything is added to return stuff to look  near new spec

Spent years on warranty work with recons and if you want a nightmare i can write a book on them

Pete

 

[dougbgt6]

Ooo! Gully, tight spot on the shaft! I'm going to have to go and have a lay down in a darkened room

 

 

[Adrian]

Here is a pic of my gt6 splines

 

[Waynebaby]

Thanks for all the replies and suggestions.

I'm pleased to say that fettling the splines did the trick. Half an hour with a needle file and 2000-grit oil and emery and the driven plate is now happy to slide up and down the shaft like a very slidey thing. What was interesting to note was the difference in the willingness of the three driven plates I now have to slide smoothly on the fettled input shaft. The original (a Luk) was the smoothest, presumably because it's had several thousand miles already on the car. The new (and flat!) plate from James Paddock (a Taiwanese Powertune) was reluctant to slide before fettling but happy afterwards, whereas the warped Borg Beck was still only begrudgingly doing what it was designed to do. I guess the difference is down to manufacturing tolerances.

Just need to get the g/box down to Mike Papworth for his tender ministrations and I can start thinking about putting things back together.

Wayne

[Clive]

I would suggest the LUK is smoothest as it is a properly made bit of kit.

Borg and Beck, anybody know who actually makes them? Frontline (I think) bought the name, but certainly not made in the same way as the proper old B+B stuff. And then we have Powertune, another natty sounding name. Hopefully well enough made  that will enable our cars to keep going for many years. But I think we need to cross our fingers!

[Pete Lewis]

and more modern design will be plated , these must not be greased designed to run dry

most old spline grease is a paste type so it wont get flung around.

Pete

[lincolnsix]

For what it's worth I bought a 3 pcs Borg & Beck kit from a Motor Factors on Ebay for around £70 for my GT6

It included instructions and a satchet of Grease and fitted with no problems.

John