Rover lt77 gearbox, Suitable Clutch Fluid?

[retroracing]

Hi there, was wondering what a suitable clutch fluid to use in my mgbV8 is??. Its got a v8 hooked up to a lt77 gearbox.

Its just had new master cylinder, slave cylinder and braided cluch hose, and new gearbox fluid too as its a freshly built car. I am however finding it hard to get all the gears all the time. All the seals look fine,its not loosing any fluid, and I have bled the system about 5 times now!!!

I used (dare I say it) ''Halford'' performance clutch fluid'' which is rated at dot 5.1. If I pump the clutch a few times before each change its easier, but just if i go to change normally, fairly often it snags on the gate like the clutch hasnt quite got enough pressure.

Would I be better off just using some good old dot 4 and is this modern stuff to advanced for an old rover hydraulic system ??????

cheers Phers!

[stevieturbo]

Dot 4 works for me.

ALthough if you need to pump, it sounds like there is still air somewhere, or maybe another issue.

Edited by stevieturbo on Saturday 31st July 19:38

[retroracing]

stevieturbo said:

Dot 4 works for me.

ALthough if you need to pump, it sounds like there is still air somewhere, or maybe another issue.

Edited by stevieturbo on Saturday 31st July 19:38

ok think i'll try some different fluid. I thought it might be the cycncros gone but definately the clutch as differrnt gears do it at different times,

[Steve_D]

How long has the fluid been in there?

Has been known for DOT 5 to react with older style seals and badly degrade them. If it is all new then probably not that.

Can you remove the slave cylinder and bleed the system with the slave just hanging on the pipe? If so then get a G cramp and make sure the piston is right back in the cylinder. Bleed the system with the slave held with the bleed nipple pointing vertically upward. This will ensure all the air will be at the top and come out of the bleed. Using an easybleed is best.

Steve

[retroracing]

Steve_D said:

How long has the fluid been in there?

Has been known for DOT 5 to react with older style seals and badly degrade them. If it is all new then probably not that.

Can you remove the slave cylinder and bleed the system with the slave just hanging on the pipe? If so then get a G cramp and make sure the piston is right back in the cylinder. Bleed the system with the slave held with the bleed nipple pointing vertically upward. This will ensure all the air will be at the top and come out of the bleed. Using an easybleed is best.

Steve

well it was sat in there for a few months when the car was being assembled, and the seals did go on the origonal master cylinder I had in there so that could be it?? I can remove the slave if I get the car in the air so i'll give that a shot, thanks

[gog]

Could it be a missmatch between the cylinders ie; bigger bore master or smaller bore slave cylinder needed, to increase travel at fork?

[blitzracing]

Have you got ATF in the LT77? They dont run well on EP80, the synco cant cut through the oil, so Rover recommended ATF in its place but thats awful stuff. Look for a site called Difflock who do a full sythetic oil for these box's, or you can try a light modern synthetic gear oil.

[Steve_D]

blitzracing said:

Have you got ATF in the LT77? They dont run well on EP80, the synco cant cut through the oil, so Rover recommended ATF in its place but thats awful stuff. Look for a site called Difflock who do a full sythetic oil for these box's, or you can try a light modern synthetic gear oil.

What does the gear oil have to do with clutch issues?

Steve

[retroracing]

Steve_D said:

blitzracing said:

Have you got ATF in the LT77? They dont run well on EP80, the synco cant cut through the oil, so Rover recommended ATF in its place but thats awful stuff. Look for a site called Difflock who do a full sythetic oil for these box's, or you can try a light modern synthetic gear oil.

What does the gear oil have to do with clutch issues?

Steve

yea i doubt that would affect the clutch, but yea got castrol syntax which is supposably the best stuff!

[Incorrigible]

gear oil, you'll be reccomended a GL4, as the old school GL5 trans fluids caused problems with the particular yellow metal used for the synchros. The modern synthetic GL5s don't have this problem though. Talk to a oil tech if you're in any doubt

The clutch issue sounds like it'snot fully disengaging which could be;

fluid leak - obvious
air in the system - bleed
mismatched master/slave - can you get a smaller bore slave or a bigger bore master. check against the old ones

Or something more sinister

[tempus]

Dot 5 is a completely different fluid,you have 5.1 fluid which has no known reactions to rubber seals,sounds like you have air in the system.

[blitzracing]

Steve_D said:

blitzracing said:

Have you got ATF in the LT77? They dont run well on EP80, the synco cant cut through the oil, so Rover recommended ATF in its place but thats awful stuff. Look for a site called Difflock who do a full sythetic oil for these box's, or you can try a light modern synthetic gear oil.

What does the gear oil have to do with clutch issues?

Steve

Only that it wont go into gear!

[Steve_D]

tempus said:

Dot 5 is a completely different fluid,you have 5.1 fluid which has no known reactions to rubber seals,sounds like you have air in the system.

Another learning day.
Just assumed 5.1 was a small variation on 5.

Steve