STP Dot 3 brake fluid ok for clutch?

[techspy]

Hi guys...my clutch started feeling a bit less responsive lately and I kinda thought it was just because of the cooler weather, but it is actually low on fluid. Is STP dot 3 brake fluid ok to use for the clutch? If not, any suggestions? I am not sure why it is low, but the red hose was replaced about 4k miles ago and I don't remember even checking the level since then. I dont have any signs of it leaking on the garage floor but I will definatly keep an eye on it from now on.

Thanks,
John
94 S4
www.skynetworks.gotdns.com

[jk1]

John,

STP DOT 3 should be fine.

If there are no leaks I would think it is probably the Master Cylinder on it's way out as that seems to be a somewhat common occurrence when replacing the braided hose on an older system, due to the increased pressure on the old seals.

As you probably know the manual recommends DOT 3 or 4 for the clutch but nothing other than DOT 4 for the brakes. Why don't you just go with a DOT 4 so you can use the same fluid for both?

Jim

[techspy]

Thanks Jim. Yeah, I will go ahead and get some DOT 4.

John
94 S4
www.skynetworks.gotdns.com

[bojangles]

can you explain how a new hose can change the pressure. the pressure come from the resistance to push on the pressure plate. It should take the same force to disengage the clutch. I can see if the red hose swells a bit that you need to push a bit more fluid into it to get the clutch to move, but the force should be the same.

Not sure how a bad master cylinder can make fluid disappear also? where would the fluid go?
Bruce

[Esprit2]

bojangles said:

Not sure how a bad master cylinder can make fluid disappear also? where would the fluid go?

Bruce,
It leaks out past the seal and the rubber boot around the push rod. In the Lotus installation, it usually drips into the footwell.

Regards,
Tim Engel
Lotus Owners Oftha North

[jk1]

bojangles said:

can you explain how a new hose can change the pressure.

Bruce,

No expert here and I'm not sure that it does. But I think the logic would be that whatever additional force (over and above the force needed to move the pressure plate) that expands the red hose would be exerted on the diaphragm and seals of the master cylinder from the non-expanding braided hose. Of course that reasoning may very well be flawed.

There are quite a few owners who swear the red hose is not a problem and vice versa, so who knows. I just know there have been reports of MC's going bad not long after replacing the hose. May be just coincidence.


YMMV,

Jim

>> Edited by jk1 on Monday 8th November 20:55

[cnh1990]

Oh guys, I would use Castrol LMA for clutch fluid.

There is a rumor that using other brands may cause the rubber that Girling uses in the seals to soften up and fail over time.

How true this is, is unknown, but why take the chance. Anyone else ever hear about this rumor? Dot 4 is fine for the brakes as they use a different rubber.

[cnh1990]

jk1 said:

bojangles said: can you explain how a new hose can change the pressure. Bruce, No expert here and I'm not sure that it does. But I think the logic would be that whatever additional force (over and above the force needed to move the pressure plate) that expands the red hose would be exerted on the diaphragm and seals of the master cylinder from the non-expanding braided hose. Of course that reasoning may very well be flawed. There are quite a few owners who swear the red hose is not a problem and vice versa, so who knows. I just know there have been reports of MC's going bad not long after replacing the hose. May be just coincidence. YMMV, Jim >> Edited by jk1 on Monday 8th November 20:55

Heat seems to make the problem worse, maybe softening up of the red hose. My problem went away after hose replacemnt, maybe it had to do with aggresive bleeding of the system.

Whatever the problem Lotus for years denied the red hose was the problem but it should be noted in later cars the red hose was replaced by the Lotus factory with the SS hose from what I understand.

What Tim pointed is true and also there might be leakage under the master in the boot. If it leaks in the front boot slight flaking of the finish will be the result as brake fluid will cause the paint to lift.