Clutch Unit

Clutch Unit

Author
Discussion

QBee

20,985 posts

144 months

Friday 10th July 2020
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Ask for advice and you should get some good recommendations - remember to say what you use the car for.

gruffalo

7,525 posts

226 months

Friday 10th July 2020
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Bogsye said:
The optimistic bit in me says give it a go, but my experience on the initial build and the drag I got from the secondary plate with it's 0.3mm clearance makes me think I'd be on a hiding to nothing.

I went to buy a clutch yesterday only to discover they'd sold out and were awaitng new stock.

On a more psoitive note I bled the brakes last night. A bit heat and cold spray had all the bleed nipples out without any drama. on checking the front pads noticed they are green - EBC Green stuff I assume. These don't seem to be well recieved in Cerbera circles, and I can't say I've ever thought the brakes were good. In my mind they seemed to lack bite, which may of course be that these need a bit of heat through them.

Probably add something more appropriate to my shopping list..
Brake pads, go for Pagid RS14, work from cold, rip your face off sort of performance, quiet and never fade. Not cheap though but you get what you pay for with brake pads.


Bogsye

Original Poster:

391 posts

152 months

Friday 10th July 2020
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Thanks both - yes Pagids look quite pricey.
I looked at a couple of PH threads on this so I think I’ll try and figure out something from that.

Between the clutch, a set of tyres and pads it should feel quite different. Bit like my wallet...

QBee

20,985 posts

144 months

Friday 10th July 2020
quotequote all
Bogsye said:
Thanks both - yes Pagids look quite pricey.
I looked at a couple of PH threads on this so I think I’ll try and figure out something from that.

Between the clutch, a set of tyres and pads it should feel quite different. Bit like my wallet...
....most weight reductions are good.... whistle


(Though I did get a vicious glare from the guy who was banging on endlessly at a TVR meeting about buying things that would take half a kilo here and there out of his road going Cerbera. Perhaps it was a bit tactless to suggest that three months in the gym would achieve far more for far less cost)

Bogsye

Original Poster:

391 posts

152 months

Friday 10th July 2020
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I think we are on the same wavelength.

I had someone at a party banging on about their personalised plate (amongst many other things) Had even been stopped by the police for it’s dodgy spelling of her name.
She was less than impressed when I pointed to my own car and suggested I could just change my name by deed pole to W663MAP and have a more accurate and cheap match. That halted the conversation.

Bogsye

Original Poster:

391 posts

152 months

Friday 17th July 2020
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My new clutch arrived today! Hopefully I'll get it built over the weekend.

In the meantime I'll take some measurements between old and new and see how the leaf/butterfly springs compare.
Hopefully I should be able to put together some form of guidance to prevent anyone else going through this rather torturous process.

billybradshaw

352 posts

148 months

Sunday 19th July 2020
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B*gger, I was hoping you’d crack this. I haven’t had any chance to work on my car in months to try and suss things out. Looks like I may as well not bother messing about and simply follow your lead and take the plunge on a new clutch.

Bogsye

Original Poster:

391 posts

152 months

Sunday 19th July 2020
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Well, a good bit of spannering yesterday.
With just the bell housing on and hydraulics booked up we seem to have a functional clutch.

Spent the rest of yesterday putting it back together. Just got the exhaust to adjust before firing it up to see if it’s all good or not.

I took photos of old and new clutch units and a selection of measurements.

Also dropped the exhaust on my face whilst wrestling it into position. It’s heavy at the best of times, but more so resting on your face. Suffice to say my eyes watered today when I blew my nose!!

My general thought is the springs between flywheel and the driven plate are the cluprit. The new clutch seems to have a different spring and it’s spaced up.

Fingers crossed. New tyres to collect tomorrow.

billybradshaw

352 posts

148 months

Monday 20th July 2020
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Sounds like great progress, nice one.


Bogsye

Original Poster:

391 posts

152 months

Tuesday 21st July 2020
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Fired it up and all gears engage nicely. Absolutely no crunch, so that’s good. It was still up on stands so I’ve still to get a feel for the bite point.

Sealed up the master cylinder cover which I think was my source of a rainwater leak, so an improve the.

Threw on the wheels with new tyres which look good. Can’t wait to take it a run!!

Bogsye

Original Poster:

391 posts

152 months

Friday 13th November 2020
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It's been a little while, but I managed to get an MOT and have put 800 odd miles onto the car.

I thought I'd update my experience with the clutch to perhaps help other decide whether to go down the refurbish route rather than buy an outright replacement. Hopefully it gives others a feel for the pro's and con's of clutch refurb versus replacement.

As a brief re-cap, I had to pull my engine out due to a shattered valve shim, which of course led onto having the heads completely refreshed, and then the bearings and rings replaced etc.. As I was that far committed, it seemed prudent to check the clutch linings and decide if these needed replaced. Looking at the history alone it seemed like they would need a refresh, and measuring their thickness confirmed that to be the case.

The dilemma was whether to refurbish the plates or replace the entire clutch unit. With the backdrop of significant outlay on the engine it's quite natural to look for efficiencies in other areas. I was always brought up on the basis that any fool can throw money at something. However, I also am mindful of buy cheap, buy twice.

I decided to try the refurbishment route. What I received back was a nice-looking unit. Everything looked decent. The plates looked good, the diaphragm spring looked fresh. All in all I was pretty pleased.

I duly fitted the clutch and got the big day of firing up the engine. Reverse and 5th were impossible to engage without much crunching. I bled the clutch a few more times. Having bought 5 litres of fluid to cover both the brakes and clutch I was horrified at the volume I have consumed on this affair!
However, despite this, no luck. It still was poor on 5th and reverse. So, out came the starter motor so that I could observe the clutch movement. At this stage it became obvious that the clearance for the plate furthest from the flywheel was insufficient. With hindsight this was because the pins with the star washers had not been correctly tightened by the remanufacturer. So, out came the gearbox.

The clutch was sent back to the remanufacturer, at their own cost for inspection.
On return the pins weren't tight, and I suspect there was a lack of understanding of how it actually worked. To resolve this I had to buy new star washers, split the clutch, tighten the pins and reassemble. This was gleaned for the good folk of this forum.

In went the clutch and gearbox, and the result was much the same. 5th and reverse, not happy. TVR owner also far from happy...

By this stage, I was fairly grumpy, and decided that a new clutch was the best course of action. This also gave me the opportunity to set the two units side by side and see what the issue could be.

The following photographs show the two units.
The upper is the refurb and the lower is the new AP unit. The profile of the spring is clearly different. You can also see the wear on the old spring


This view shows the units sat side by side on the ground - not the best photo, in terms of their respective height.


The new spring certainly looks to be at a better height than the old one. The gauges of the springs seemed to be the same. The primary spring - nearest the flywheel - was heavier than the secondary, on both units.

Similar photograph, perhaps better illustrates it.


Stepping back for a minute. The refurbishment process sorts out the friction lining and, I believe the diaphragm spring. The main problem is the 'leaf' springs that open the clutch at the primary and secondary plates. Those are not available as spares. As far as I understand AP will take the unit back and replace those, but the timescale is not too predictable. I suspect the desire is to supply a whole new unit.

The second issue that prevailed was flywheel wear. This corresponds to the wear on the springs noted above. When refitting the clutch, the key is to ensure that the springs are mated onto a 'fresh' part of the flywheel face. In my case I rotated the clutch round by one mounting hole. However, if the car has had a few clutches then the chances are that the flywheel is showing wear at either side of every clutch mounting hole.

Here's the wear either side of one hole.



Whilst that wear doesn't seem like much, when you couple that with tired/worn springs and a very small distance to open and close the clutch. it spells disaster. As I understand the clutch plate clearance is about 0.5-0.75mm. Tired springs and a worn flywheel are soon going to wick up that and give you a dragging friction plate.

cont....

Bogsye

Original Poster:

391 posts

152 months

Friday 13th November 2020
quotequote all
In my case I have a new clutch mounted up on the best portion/orientation of the flywheel. If I'm lucky enough to be fitting the next clutch, then I'll be ordering a fresh flywheel for it, as it's likely going to be showing some wear.

At the end of the day the refurbishment route didn't work out for me. It's worked out for others, which is great. I'm hoping that the above helps fellow Cerbera owners gauge whether a refurb is a good route or not.

On the face of it, if you are doing your own spanner work, then £150+vat for re-ling the friction plates looks pretty good. If it's a known good clutch, then perhaps one refurb on a good flywheel is possible.

However, if you're paying someone else for their time to pull the gearbox and replace the clutch, then I'm not very sure the economics are all that good. Yes, it's a lower parts cost, but if the refurbishment doesn't work out, then the additional labour of removing the gearbox once more will wipe out any saving, plus you'll have the joy of buying a new clutch.
In this case I returned the clutch unit and received a full refund. It was still painful doing this work on my driveway, but on the plus side, I’m now pretty good at pulling the gearbox and clutch out.

Ultimately it seems a pity that for the sake of some pretty cheap springs the main clutch components have a relatively short lifespan.
Anyway, hopefully this is food for thought for anyone else contemplating a clutch and flywheel change.

Cheers,
Brian