Topping up clutch fluid?

[CerbWill]

Is it usual for these cars to naturally lose a bit over time? Having tackled the slave cylinder last Christmas, putting in the upgraded RP slave, I'd rather hoped I'd seen the back of clutch issues but it felt a bit odd today so thought I'd check the fluid, sure enough there wasn't much in the master cylinder, so I've topped it up and bled it for now. Did seem to be quite a lot of black crud in what came out, presumably from a seal somewhere so it doesn't look good, unless that as the new slave seals bedded in a bit (hopeful thinking there)?

[CerbWill]

I didn't change the master. Fluid level dropped overnight and some kitchen towel I left underneath it is soaked in clutch fluid. Not good news.

[CerbWill]

I've got some original TVR cats in mine. It's leaking from the joint between the bellowing and the gearbox, which suggests its the rear seal that's failed, rather than the seals internal to the slave. TVR's idea of using the bellhousing to deliver fluid to the slave is fairly ridiculous in my opinion. It just adds an extra layer of complexity that isn't required. When I've got it all disassembled, which will be some time from now, I'll measure it all up and see if I can get a Tilton 6000 series to fit.

[CerbWill]

Crypto, did you need to change the master cylinder for a larger bore when you put the Tilton clutch in? Looking at their website their slave cylinders all have the same hydraulic area and same maximum throw. If I've done the maths right it seems that a 7/8" master cylinder is needed provide the required volume of fluid for maximum slave travel.

[CerbWill]

Well its all off the car now. Looks pretty terminal for the slave after 8 months and 4000 miles, done with Dot 4 fluid and cats in for reference, although as the cats are positioned further back down the transmission tunnel I'd have thought the airflow underneath the car when its moving would have kept a lot of the cat heat away from the bellhousing.




Anyway, having had a quick measure up there's not enough space in the bellhousing to fit an aftermarket slave without modifying the housing. My plan is to remove the centre of the housing that the standard slave bolts to, and fit one of these.

http://tiltonracing.com/product/6000-series-hydrau...


As part of all this I'll have to get some new clutch hoses made up, so does anyone know what thread TVR used for the connector in the offside wheelarch?

Edited by CerbWill on Wednesday 22 September 08:29

[CerbWill]

ukkid, my RP slave doesn't feel like its supposed to come to pieces by hand so, at least it didn't pretty much fall to pieces like my original TVR one, so I assume its probably best to send it back for refurb.

Irritatingly the input bearing retainer on my gearbox is broken.



Could someone with an intact one please measure the OD of the bearing retainer shaft so I know which variant of the slave cylinder I need to buy? Obviously my one needs replacing, so if anyone knows the correct part number I need that'd be great. I'm going to try googling the numbers that are on my bearing retainer and see what I can find. TVR Parts want £100 for it which seems a joke as they're available for $70 USD inc shipping, just need to know I'm ordering the right one!

Edited by CerbWill on Wednesday 22 September 08:30

[CerbWill]

Bit of an update. Master cylinder has had it's seals changed. Ukkid has kindly sent me his spare gearbox input shaft retainer which arrived today.


Clutch Bellhousing altered with a 114mm hole saw.



And cleaned up a bit.



Input bearing retainer fitted, and threaded mount for slave cylinder in place.



Its here that I've hit a problem. When screwing the slave cylinder onto the threaded mount the mount hits the inside of the slave piston before I've wound it on enough to achieve sufficient clearance, so I need to cut the mount down a bit. That's tomorrow's job. From there I'll be able to figure out the best place to drill a hole in the bellhousing to pass the hydraulic pipes through, and then it'll be time to battle the gearbox back onto the car.

Edited by CerbWill on Wednesday 22 September 08:33

[CerbWill]

I got the 52mm radiused bearing 60-6000 from Competition Supplies, which has actually given me another problem. Some photos of the 6000 series show it coming with an anti-rotation bolt but mine didn't. I need to drill and tap a hole in the bearing retainer for an anti-rotation bolt to stop the whole slave assembly rotating. I can't use the mounting holes for one as the bolts are too big. Also, my dremel has just died. Seems TVRs aren't meant to have clutches today! I'm not fitting a clutch stop (yet) because the master cylinder shouldn't be able to move enough fluid to max out the available slave piston travel.

Edited by CerbWill on Saturday 22 August 13:22

[CerbWill]

And its done. Hopefully I'll get it back on the car tomorrow.

Edited by CerbWill on Wednesday 22 September 08:35

[CerbWill]

Thanks guys. Gearbox is back on now. Time to find the best way of routing the clutch feed pipe. I've got the standard pipe wit an adapter to join to the 30cm hose that came with the slave so I've got a bit of slack to play with but now much.

I think it cost about an extra £120 over a raceproved slave, so we'll see how long it lasts.

[CerbWill]

And we have (possible) success! With the car in gear I cant turn the propshaft with the clutch out, but can spin it freely with the pedal in. Pedal feels lighter but less movement is required so I think I'm going to end up drilling another hole higher up the clutch pedal arm to increase the pedal ratio. I need to finish off the reassembly and try it out whilst driving first though.

Also had a 'Classics from the Mrs' moment trying to bleed it. She's been well trained in clutch bleeding through her fascination with Wheeler Dealers but she jumped in and pressed the pedal. No clutch fluid being sucked into the master cylinder. "Oh dear" thought I, worried I'd messed up rebuilding the master cylinder. But I thought I'd check she was actually pressing the clutch pedal, "yes, the middle one" she replies. She's been driving for 10 years.

[CerbWill]

Victory is mine! Its all back together and, after a protracted battle with TVR's legendary electrics, its all working. As mine is an early car it has the bulkhead connector in the engine bay and that did not like being disturbed. First it wouldn't even turn over as the starter solenoid wasn't getting 12v, so I replaced that wire. Then it wouldn't start because the ECU thought the throttle pots were remaining at 9.4% regardless of position, so I re-seated the plug, and then it ran, but on 1 bank only because the o/s injectors were only getting 8.5v instead of the full 12v, a quick clean up of the plug with a dremel and a soft wire brush, and finally all was well. The clutch does indeed work as a clutch, however the pedal travel feels quite limited so I'll measure up my other cars and see if I can adjust the pedal ratio to make the travel distance more normal.

To quote James May after sorting his BMW's head gasket in the Middle East Special 'He's made his point. I have triumphed over him. So he can sod off, frankly. Cerbera clutch designer, take note!

If anyone needs part numbers or any advice to help them do this on their car PM me and I'll help if I can.

Edited by CerbWill on Sunday 30th August 17:17

[CerbWill]

I could do. Willwood & Girling both make 0.625" diameter master cylinders, the Cerb being 0.7" as standard, so that would seem to give an extra 25mm pedal travel. It takes about 10cm of travel to disengage the clutch, vs about 15cm in my other cars (admittedly both run of the mill Renaults) so my options are, move the pushrod 17-18mm up the clutch pedal arm with the standard master cylinder, fit a new 0.625" diameter master cylinder, or fit new master cylinder and move the pushrod about 8 or 9mm higher.

[CerbWill]

It works fine and I've adjusted the clutch pedal so it hits the trim panel behind the pedals just after the clutch is disengaged to prevent excess movement which could damage the fingers, it just doesn't feel 'right'. A 0.625" master cylinder is on order.

[CerbWill]

Martin, as I'd adjusted the clutch pedal so that the threaded rod would hit the trim panel just after the clutch had released there was no possibility of over-extending the clutch but the total pedal travel just felt too short. I've since changed the master cylinder for one of 0.625" diameter and the pedal feel and range of movement is much better. I've now completed roughly 200 miles on a trip to the in-laws and back without issues.

[CerbWill]

Well a year and 6000 or so miles later and mine is still going. I've changed the fluid a couple of times but its not losing any.