Griff Clutch replacement (Sods Law!!!)

[737flf]

My Griff 500 clutch started slipping today, oh joy!! Just as I am in the middle of three weekends of Lowland Championship sprints and hillclimbs (Five events). I am about to embark on replacing it myself, unless anyone knows of somone decent in west/central Scotland who can do it for me without charging like the cavalry. As time is of the essence, I would be grateful for any advice regarding pitfalls to be aware of as the subject is not particularly comprehensively covered in the "Bible".

I am a better than averagely able spanner man and I do have access to a pit, which helps a bit, but any advice would be much appreciated as I have to get this done by Friday night.

TIA

Al

[350Matt]

Hello Al

1st question T5 box or rover?

[737flf]

Hi Matt, it's a T5.

[DarkMatter]

I've recently changed my clutch (and gearbox) - it was quite straightforward.

I bought parts (AP) from TVR Power (other suppliers are available).

Some people say you can detach the remote control from underneath, but I can't see how because where the remote control mechanism is fixed to the gear leaver there is a plastic sleeve which is hard to remove/replace - and it's worth replacing that sleeve and plastic washers to remove slack from the gearchange. So, to separate the remote you I found it easier to remove the tunnel 'T' cover inside.

To remove the tunnel cover you need to fully slacken the handbrake to get the lever in a near vertical position. Underneath the tunnel cover is a fibreglass panel which is screwed/sealed to the transmission tunnel. You may want to have some sikkaflex to hand for re-sealing afterwards.

You'll need to remove the exhaust and propshaft, so you may want to replace the prop to diff flange bolts while they are off.

It may be easier to separate the box from the bellhousing first. This also makes it easier to get to the part of the remote gearchange which is at the top of the bellhousing.

It would be worth replacing the clutch release fork as these have been known to fail - I believe that strengthened ones may be available somewhere.

May as well fit a new release bearing too.

If your tempted to replace crankshaft spigot bush then beware - it will 'shrink' when fitted so you may want to ream it out with a 15mm straight reamer.

Good luck!

[2Munkys]

If you have means of getting underneath then it's a nuts n bolts job and to be honest, one of the least unpleasant Griffy tasks to undertake. You just need a bit of dexterity, basic tools and strong arms and shoulders.

Note in the first shot that the selector gubbins has been left in situ. Check a few items over whilst it's all apart such as: excess wear in the spigot bush (which'll need greasing before reassembly) and the clutch actuation mechanism for damage/wear (the lever has been known to crack). Change the thrust bearing and gearbox rubber mountings.

[lewis_sharman]

DarkMatter said:

If your tempted to replace crankshaft spigot bush then beware - it will 'shrink' when fitted so you may want to ream it out with a 15mm straight reamer.

Good luck!

When you say it will shrink, what do you mean? I will be doing this in the next few weeks and am trying to gather as much info as possible. Was there a 'nack' at all to getting the old spigot bush out?

Pics if possible

[350Matt]

I'd echo previous comments about leaving the gear lever in place and undoing the 4 bolts holding the plate to the top of the selector housing.
also you can leave the bell housing in place on the engine, just undo the four big allen headed bolts ( a long 3/8 extension helps here)and then withdraw the box.

Getting to all the bell-housing bolts is then easy if you need to get to the clutch.

As to replacing the spigot( although I'd be very surprised if you needed to) the easiest route is to pack the hole full of grease and then drive a tight fitting bar down the middle to hydraulic the bearing out.

They should only be a light interference so you may not need to ream out after fitting a new one, its a good precaution I suppose.

[lewis_sharman]

The clutch is fine, the spigot has been diagnosed as the horrible grinding noise on mine which is why it has to come out.

[crackedfinger]

May as well change the rubber fuel line too (looking at that pic it's dead easy to get to the usual tricky end!)

[DarkMatter]

lewis_sharman said:

When you say it will shrink, what do you mean?

The spigot bush is an interference fit. Because the bush is an interference fit it will compress when fitted.

lewis_sharman said:

Was there a 'nack' at all to getting the old spigot bush out?

I drilled through my old one until there was just a thin wall left and then collapsed what was left with a screwdriver. I didn't try the hydraulic method as mentioned below by 350Matt.

350Matt said:

As to replacing the spigot( although I'd be very surprised if you needed to) the easiest route is to pack the hole full of grease and then drive a tight fitting bar down the middle to hydraulic the bearing out.

They should only be a light interference so you may not need to ream out after fitting a new one, its a good precaution I suppose.

lewis_sharman said:

The clutch is fine, the spigot has been diagnosed as the horrible grinding noise on mine which is why it has to come out.

I found the new bush (from TVR Power) hard to refit. I asked on here and was told to hit it hard, so I did (protecting the bush with a block of wood). When I refitted the gearbox the input shaft felt like an 'interference' fit in the bush but I carried on regardless. This was a bad move.

After a couple of hundred miles I started getting a horrible graunching noise when changing gear although the gearchange itself was smooth (no synchro problems).

Subsequent diagnosis showed that when the engine/transmission heated up the input shaft had seized in the spigot bush, enough to start the bush turning in the crankshaft. The bush wore itself away enough to just drop out of the crankshaft when I later removed the clutch. The graunching was due to the spigot bush moving and coming into contact with the clutch plate when changing gear.

I sourced my replacement spigot bush from the very helpful TVR Shop (Racecar Direct http://www.racetechdirect.co.uk). They provide me with a slightly tapered bush to make fitting easier.

I borrowed a T5 input shaft from the very helpful Gearlink Services http://www.gearlink.ukf.net to align the clutch plate and check the fit in the spigot bush.

I had a drift made up with a shaft the same diameter as the input shaft and used that to protect the new bush as I tapped it in. It went in easier than the first bush, however, the bush had compressed enough to be a tight fit for the input shaft. That's why I then used a 15 mm reamer to open out the bush to prevent it binding on the input shaft.

Not everyone experiences the same problems that I did when fitting a spigot bush.

(edited to correct typo and to add that I'm referring to the Spigot bush used on my Griffith with a T5 gearbox. The spigot bush for an LT77 box has thicker walls and may not compress so much when fitted.)

Edited by DarkMatter on Wednesday 17th June 17:42

[lewis_sharman]

I hope not

Cheers for the heads up though i will definately look out for this

[737flf]

Well, by 15.00 last Friday I had everything stripped down to the extent that, in theory, all I had to do was to undo the four bolts securing the remote input and the four bolts holding the gearbox to the bellhousing. Could I get at them?(The ones on the remote) not a chance. The plate on the remote has an upward swaged lip which, although one can get a small socket on to them (but not be able to swing ANY sort of ratchet) also precludes the use of any spanner, ring, ratchet or otherwise. I then took off the transmission cover only to be faced with acres of GRP, so, using my trusty angle grinder I cut away the relevant bitsonly to find a remote which defied all attempts to dismantle it. Not knowing what bolts onto what (In the absence of a proper workshop manual, or photographs), I was loth to proceed any further as previous experience has taught me that, in ignorance, something expensive will be broken.

So I put it all back together so as, then at least, I could compete at the weekend.

If anyone has photos which would be of help, ANYTHING!!, I would appreciate it if they would post them as my only alternative is to throw myself on the mercy(Hah!) of (That rare beast in Scotland) a TVR specialist.

TIA

Al.

BTW Thanks for the help from all you guys so far.

[shpub]

Did you try the remove the gearbox mounts propshaft and letting the gearbox drop a little? This increases the clearance.

The bellhouse bolts need a LONG extension with a wobble end and a decent allen key bit.

[350Matt]

seconded, you need to support the engine on a jack and allow the back of the box to droop down a bit you can then get a tiddly 1/4" drive ratchet and socket onto the bolts