Fly wheel issue

[Rufus Roughcut]

Today I set about replacing the clutch slave cylinder as over the past few months the fluid drip had grown from a 5P size over the week to a downpour...also I thought it wise to replace the master at the same time.



Apart from the limited space when working in a single garage, all was going well until I removed the bell housing.

From the pic you can see a couple of score marks on the casing, these were caused by one of the clutch pack mounting screws being loose. No problem thought I, just needs tigtening up...Uh oh.. the screw just turned in the hole.



I flicked through some old receipts and found that the clutch and slave had been replaced about 4K miles ago (before I took ownership), part way down the receipt was a charge for a heli coil being fitted to the flywheel. So.. it was either fitted incorrectly or it would prove that heli coils are a bodge when it comes to clutch packs and flywheels.

What are my options now ?

Is it possible the flywheel can be repaired, properly ?
Off the top of my head can the hole be welded up and a new thread cut ?

OR

Do I splash out on a lightened Raceproved jobbie (Not something I'd budgeted for).

Will the lightened flywheel cause any undesirable effects on a road car?

Thanks

Mark

[itiejim]

A properly fitted helicoil will be fine - though I wouldn't automatically assume that it was one loose bolt that caused the problem. Mine bell housing had some scoring when I removed it though all the bolts were tight. TBH I don't think the accuracy of the casting is up to much. I relieved mine a little and it's fine now.

[tvrfan007]

In my experience helicoils are normally only frowned in high temperature applications. I can't imagine it's got hot enough to worry a helicoil, my opinion would be that someone didn't fit it properly in the first place as it's common to helicoil the exhaust manifold on Rover's T series and they can tolerate extremely hot EGTs.

I wouldn't be particularly keen on welding one hole up in the flywheel as it's localised working of a balanced component. You can of course fit a decent second hand flywheel as opposed to procuring a lightweight variety. I'd be inclined to inspect the hole and helicoil it properly, possible even with threadlock if you're worried.

The pros of a lightweight flywheel are obvious, and the cons are usually few with some exceptions. Excessively light flywheels can make the car a mare to drive on the motorway due to speed variation where you lose the inertia effect. I believe the Cerbera flywheels to be quite light as standard. In my Rover I went from a 9.7 kg standard flywheel to a TTV racing 4.4 kg billet flywheel - the only effect is starting is sometimes a little trickier but driving it around there is no problem.

[kevin63]

Would the option of a threaded insert like an E-nut and locktited in be ok, they are stronger than a Hellicoil.

[tvrfan007]

So are these: http://www.timesert.com/

[Rufus Roughcut]

Thanks for the info guys, as always much appreciated

The flywheel is still on the car at the mo, I'll hopefully remove it tonight to get a better look at the problem.

[ridds]

I'd pull it out and check the condition first. A new correctly fitted helicoil should be fine providing there is not too much damage.

Welding up will be fine, TVR is not renowned for it's finely balanced components, plus the tiny amount of weld will my nigh no difference providing it's dressed correctly.

[gruffalo]

I light fly wheel does not have a bad effect on the car, I have one and no oproblems.

[Rufus Roughcut]

I've done a little reading up on TimeSert thread inserts, they do seem to be what I'm after and a better solution than a helicoil.

The lads at work said in the past they've made there own by drilling and tapping a 12mm hole (original screw is an 8mm thread), fitting a 12mm bolt and then drilling and tapping for an 8mm thread, sounds like a good solution.

I've measured the distance from the original thread to the clutch surface and found it to be 2mm, so this puts that idea to rest.

So it's back to the Timeserts......

Since removing the fly wheel I've found another with partially stripped threads, but.. I'm still left with a dilemma.

A kit will cost the best part of £100, which is roughly a third of a new flywheel.

From the pics do you think the wear on the fly wheel plus the need to fix the threads justifys a new one ?






Mark

[sonnylad]

Is that Bellhousing the old style as it appears to be different from mine, if so thats your problem as the old style clutches are no longer available.

[Rufus Roughcut]

sonnylad said:

Is that Bellhousing the old style as it appears to be different from mine, if so thats your problem as the old style clutches are no longer available.

Having trawled through clutch/gearbox threads, I believe it is the later type, the car for info is a 98 4.5

The scouring was caused by the wayward screw, you could clearly see it was protruding 3-4mm further than the rest and it was covered in aluminium dust

[SimonKD]

Rufus Roughcut said:

Thanks for the info guys, as always much appreciated

Hi Mark YHM

[tvrfan007]

Pic has a strange hole, but you can move and redrill the holes. Index them round.

Edited by tvrfan007 on Tuesday 12th October 14:43

[Rufus Roughcut]

These blooming cars are a mine field..

Could someone please take a look at the pic below and tell me which bellhousing is the early casting and which one is the later. I've already had confirmation I've been running the later clutch and the raceproved slave is the same size as the one I took off.