Clutch fixed!!

[srubrn]

Well I think so anyway. I took my truck in for the hard pedal and they were going to only put a slave cylinder/throwout bearing unit in. After really thinking about the issue, it happening only in the warm months. I came up with this. The problem is that there is DOT 4 fluid in the clutch and it has a lower boiling point than DOT 3, plus mine was very dirty and probably full of moisture and that even lowers the boiling point more. I suggested they only change the fluid over to DOT 3 by sucking the old out.

Anyway I took it in and they called and told me they were going to put in a flywheel, clutch, pressure plate, and slave cylinder/throwout bearing unit. They also told me there was a new flywheel out that fixed the noisy flywheel issue. Since it was under warrenty, I told them to knock themselves out. They over-nighted a flywheel from Canada and it is all in and no hard pedal so far. I have not towed with it yet to further test it. I am willing to bet that if they would have only changed the fluid to DOT 3 that would have fixed it. They did however put DOT 3 bck in it due to the fact that did not have any DOT 4.

So if you got the problem, try changing the fluid yourself and see what happens. Really cheap fix.

[Jelisfc]

Thanx for the update. The million dollar question is the new flywheel used in production and after what date? My 03 doesn't rattle but it was built in Oct 02. Since your dealer seems in the know maybe you can find out.

[chuntag95]

There are some really good Dot 3 fluids out there. ATE Super Blue is inexpensive and had a wet boiling point that is way up there. It is usually higher than the dry boiling point of the cheap stuff. I changed out my brakes and boy was the fluid nasty in there! :eek: It is also the stuff they use in sports cars and some race cars. Overkill in some cases, buy the properties make it worth the extra money IMO.

[srubrn]

Jelisfc,

Next time I go up there I will ask. he said there was something on Techline about it.

[Jelisfc]

Sounds good. I'm leaving town for two weeks in June. This may be the right time to get all the little bugs worked out.

[jbplock]

DOT-4 actually has a higher boiling point than DOT-3. The problem is that both DOT3 and DOT4 absorb water (hydroscopic) which lowers the boiling point. See the following link for some interesting brake fluid info.

http://www.rpmnet.com/techart/fluid.shtml#fluid

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[a64pilot]

OK glad it was not just me. I thought the higher the DOT#, the higher the boiling point, Besides if you actually get it hot enough to boil it should result in a soft-spongy pedal and maybe even a slipping clutch, not a hard to press one.

[srubrn]

Well where did i get that info from. Your right and I am wrong. Maybe all the new prts is what fixed it. I would try just changing the fluid for a cheap try.

[Jelisfc]

The ATE fluid is DOT 4. Can you do a brake fluid analysis like for oil and fuel? If there is a high level of water in the fluid it will lower the wet boiling point. Going to a high quality fluid should do the trick, as long as nothing else has been damaged due to a dragging throwout bearing etc.

With brakes you get spikes of high heat soak. A hyd clutch will not see high spikes but a continous heat soak. If all the fluid is heated during a long drive and the water content is high enough that may explain the condition we see.

I'd be curious to see the specs on the OEM fluid.

[srubrn]

Are all of ya'll familiar with the slave cylinder throwout bearing unit.

It's a one piece unit that goes around the input shaft in the transmission bellhousing. It looks like a dounut with a hose attached.

[RealBigTruck]

If it really is a fluid issue, it might be worth a few guys chipping in together and getting a tin of Castrol SRF. It's $75/half liter, but it hardly absorbs any water at all, giving it a wet boiling point of 519F.