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Clutch problem

Postby Simon Mason » 08 Sep 2017 07:22

My son and I are very pleased with the GTV8 ,Which we converted with an SD1 engine and gearbox,We put in a V8 clutch master cylinder as per the book "How to give your MGB V8 power", but find the clutch bites very near the bottom and just feels uncomfortable but works ok. The clutch has been bled many times but is no better.Has anyone else had this problem? Also the gearbox works fine and is quiet but jumps out of third gear going down a hill? Any advce would be most welcome.
Simon Mason
 
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Re: Clutch problem

Postby Nic Houslip » 08 Sep 2017 09:22

Simon

If you can reply to the questions below we may be able to figure out what can be done.

Does the clutch bite as you release the pedal, in the first few centimetres of travel?
Does it then take up the drive in a very short travel, rather like an on / off switch?
Is the clutch plate new or was it with the engine when you installed it?
An extra question; does the clutch cylinder get air in [spongy feel] or remain hard?

Nic Houslip
Nic Houslip
 
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Re: Clutch problem

Postby Mike Howlett » 08 Sep 2017 09:57

A thought about jumping out of gear. How close is the gear lever to the front edge of the hole in the tunnel? Could it be possible for the lever to be nudged by the edge of the tunnel when decelerating? If that is the case you have an easy fix by just opening the hole a small amount.

I have the R380 gear box on my conversion and have also used an MGBV8 master and a GSY101 Rover SD1 slave cylinder. My clutch is fine, if a little heavy.
Mike Howlett
 
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Re: Clutch problem

Postby Paul Gill » 08 Sep 2017 10:29

Hi
Many years ago I had these problems, when running without the gear lever gaitors, it would not jump out of 3rd, with the rubber gaitor it would not jump out of third, so I shopped around for the 'leather' gaitor that was 'slack' or not such a tight fit over the rubber one.
Under load you should not be able pull it out of gear, while on over run it can be pulled into neutral, possibly if the detent springs are worn it will make the shift into neutral that much easier!

For clutch disengagement I remember fiddling about with the length of the actuation rod and putting a smaller slave cylinder on, from memory I went from 1" to 7/8" diameter to give me more travel, seemed odd to have to do this when I renewed the clutch as I was using stock items.

Paul
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Re: Clutch problem

Postby Simon Mason » 08 Sep 2017 14:18

Hi, Thanks for replies, The clutch seems to take up normally but very near the floor, clutch does not seem spongy and yes it had a new clutch fitted on assembly, And we will take off the gear lever Gaiter and see if there is a problem there.
Simon Mason
 
Posts: 34
Joined: 11 Jun 2014 08:05

Re: Clutch problem

Postby Nic Houslip » 08 Sep 2017 15:54

Simon
OK, that rules out the clutch plate being worn thin, it probably now down to matching the master cylinder diameter or the slave cylinder diameter or adjusting push rod lengths. If you need more info on what parts are used in SD1, GTV8 I may be able to look them up. See also Paul Gill's reply. Did you fit the SD1 gearbox, I can't see it mentioned. I have a BGT Roadster with SD1 gear box, and an RV8 with same box and they are not prone to dropping out, but the MGB GT box may do that.

Nic
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Re: Clutch problem

Postby Simon Mason » 08 Sep 2017 16:17

Hi there, Yes,both engine and box are SD1.
Simon Mason
 
Posts: 34
Joined: 11 Jun 2014 08:05

Re: Clutch problem

Postby Simon Mason » 12 Sep 2017 11:15

Hi, I have taken off the gaiter completely and still jumps out so am assuming i will need a recon box, Although i don't know where i could get a recon box for such an old model.
Simon Mason
 
Posts: 34
Joined: 11 Jun 2014 08:05

Re: Clutch problem

Postby Nic Houslip » 12 Sep 2017 15:32

Simon
The gearbox is almost certainly the LT77 version and I am pretty sure that all the parts are available, so having a gear box specialist dismantle, replace worn parts and rebuild is possible. You might talk to Clive Wheatley as I'm pretty sure he knows someone who can do this, if he hasn't got a solution ready in the way of a rebuilt box at hand. See http://mgv8.homestead.com/index.html

The RV8 workshop manual has complete detailed instructions for repairing the LT77 and R380 gearboxes which are in the same case as the SD1 box. The job however isn't for the faint hearted. The LT77 was used in Range Rover, Discovery and Defender models [with variation on gear lever selector mechanisms, transfer case [for 4WD vehicles] and some other vehicles. The jumping out of 3rd is probably only matter of replacing the 3rd gear synchro clutches and the detent mechanism. And if you want another solution, I have a complete SD1 engine and Automatic box in my garage...
Nic Houslip
 
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Re: Clutch problem

Postby Mike Howlett » 12 Sep 2017 17:50

I don't know where you live Simon, but up here in SW Scotland we have companies like this one https://www.neilengineering.co.uk/index.php/5. There ought to be someone similar near to you I would have thought.
Mike Howlett
 
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