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Silicone vs Dot 4/5 in new CLUTCH hydraulics?

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Brosky

Brosky

Great Pumpkin
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I'm reposting in the event that others may not have seen the discussion within the previous thread about the clutch, which has taken on a bit of another life. My clutch pedal hit the carpet with no resistance yesterday and there was fluid on the garage floor. I have no complaints after 32 years and I'm happy that it wasn't on a trip or in rush hour traffic.

Today I ordered a brand new "complete" hydraulic system for my TR6 clutch from Moss, including master & slave cylinders, braided stainless flex line, steel pipe and joint fitting and new silicone fluid, mainly to protect my paint under the hood. There will be nothing old left to fail or to contaminate the new fluid.

After doing so and reading various posts with comments to my situation it was brought to my attention that I may have issues with swelling and possible premature failure that may be caused by using the silicone fluid.

Moss tech support was rather non-committal one way or the other about what may or may not happen, so I'm curious to see what other experiences or thoughts are out here supporting either one or the other.

I'm open for suggestions BEFORE I put the fluid in, so fire away.
 
My guess is that if you are using new, not NOS parts, the seals will be fine. Is is possible that some of the older seals in NOS parts may be affected in some way by the silicone fluid and cause premature seal failure. I would not hesitate to put in silicone using new parts, especially since every part is new, now is the time.
 
I have never used Moss hydraulic parts. I have used TRF and VB with silicone. TRF has held up quite well while VB has been garbage.
I also have silicone in the original hydraulics in my TR3. I bought the car with 22,700 miles on it coming out of 22 years of storage. There was no evidence of work done in that area. After 13 years, everything still works great.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

Hello paul,

I have used Silicone brake fluid in all my cars for twenty odd years, I would use nothing else.

Alec
 
Hi again, Paul.

I completely rebuilt or replaced every component and line in my brake and clutch systems when I restored my car 1996-2001, so I can't comment on the old discussion about whether it's OK to switch from "regular" fluid to silicone without changing other parts. My clutch master cylinder, rebuilt by me, did end up pooping out a couple of years ago, and I replaced it with a new one. I did not see any signs of darkened silicone fluid or degraded seals when I took the old one apart. I suspect that I did not do a very good job honing it or whatever. It worked, I just had trouble getting enough stroke to reliably engage first or reverse. New master cylinder = no more problem.

I had Apple Hydraulics resleeve my brake MC with brass, and my brakes have always worked great from day one--I'm just now coming up on changing my front pads for the first time since the rebuild. I have put miles on that car! I have never noticed a soft pedal response or anything like that at all, although I don't really get a chance to compare driving my car with driving other LBCs.

Incidentally, I do have the "Magic Clutch" parts in my car, although I did not source them through TRF. Seems to work fine.

I guess I'm taking a long time to say: go with silicone. There's not much downside, at least none I've experienced in five years.

Good luck,
 
I've been running silicone for at least 15 years and never had a problem. It's nice not to have to worry about the paint and moisture issues. Go for it.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

Im replacing my leaking clutch slave this weekend. The master is leak free. I ordered a replacement from BPNorthwest. Is there any reason not to switch to silicone? I like the idea of not being as concerned about corrosion.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

Paul,

All hydraulic components in my 3 are Girling.
I have used silicone Dot 5 with no problems for twelve years now.

You may want to stick with Dot 4 if you are leaving your brake fluid system to Dot 4. This means no excuse or reason to possibly put in the wrong type fluid in the wrong master. Unless you plan on replacing the entire brake system I wouldn't add any dot 5 to the brake or clutch system for the reason previously mentioned.

That being said here's my story,

I replaced new all brake and clutch lines as well as the rear brake cylinders. I Rebuilt master brake, master clutch, clutch slave, and both front brake calipers. I Bought all parts from local supplier of British parts twelve years ago who I will not recommend unless you live close enough to harass weekly for the the parts you ordered. I originally installed Carter Silcone DOT 5 brake fluid. Bled all lines of air and so far have never had a problem. When I flushed the system this last time I bought the DOT 5 silicone fluid from NAPA and all is still fine. Now that I have totally cursed my hydraulic system to fail this winter due to the Triumph Girling Gremlins I wish you luck with your clutch hydraulic system install.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

Thanks Harry, but I think that you get a pass on the curse, at least for this year.

Before I ordered the parts from Moss, I asked to verify that they were all Girling parts and the sales confirmed that to be true.

I will go with the silicone and will make a very nice label for the cap stating what is in one versus the other. I may redo the entire brake system this summer anyhow, so at that point it will be silicone all around,

Thanks to all for the advice.

And Mike, come around more often!
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

Here we go again with the sales guys who say anything to get your order. When I called Moss to order the parts yesterday, I specifically asked for Girling cylinders and I asked if the steel line was preformed for the m/cyl to slave and he said yes. WRONG! The line wasn't pre-bent and still cost $26.95. I hate being BS'd! Just tell me the truth.

The good news is that I got all of the Moss parts today (overnight, but no extra charge since it came from NJ to RI), even though one was wrong. The cylinders are Girling and they did end up having the SS flex hose as well.

I just called Dave at TRF and they have the pre-bent lines in stock, so I should have it by Friday. If Moss had been truthful, I could have ordered it yesterday and had it tomorrow.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

Paul:

I did not intend to put you off using silicone by telling you my own story of woe in the other thread. I would not use anything else myself - even if I had to rebuild the M/C each year! The current setup I have (girling kit from TRF and stainless resleeved M/C from Apple) is working fine. Just wanted you to be aware that if the clutch does start to "stick" after rebuilding the hydraulics, it may not be the throw-out bearing/forks assembly (which was my initialy thought when it happened to me), but in fact the M/C.

Anyway good luck with the rebuild, and let us know how it goes.

Rob.
Rob.
 
Paul,

I'll make this brief.

Silicon.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

Like Ned, Mike and Alec, I have used silicone for many years. My TR3 has used silicone for over twenty years. All cylinders were new or rebuilt at that time. The only problem was a failed brake switch which I replaced with a mechanical switch -- the TR4 mech switch lasts the longest. My TR8 has used silicone since I bought it five years ago. I flushed out the system with denatured alcohol, replaced the MC and one wheel cylinder with new, rebuilt the clutch slave cylinder and haven't had a problem since.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

Hi Guys,

How often do you change your Dot 5 fluid? I was reading about Silicone fluid and when/if water gets into the system (heat/cold causing condensation, through the rubber hoses, reservoir vent holes, around cylinders bores etc.) the water will tend to settle to the lowest point. Potentially this could cause corrosion in wheel cylinders or lines and cause pedal fade if the water starts to boil.

I'm not trying to start a debate about Dot 3/4 vs Dot 5. I've used both over the years. Just wondering if you still change it on a regular basis or test it somehow.

Cheers,
John
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

I change mine about every four years. The stuff isn't cheap, but I feel it is well worth the price. It has saved my paint on a couple of occassions (I spilled it while bleeding) and has been trouble free.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

I bleed the brakes every year - although this may not help get the moisture out if it is in the system. Water will accumulate at the lowest point, but bleeding only takes fluid from the highest point of the master cylinder being bled. A full empty and refill would be needed to get the water out of a silicone filled system.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

Silicone it will be.
 
Re: Silicone vs Dot 4/5 in new CLUTCH hydraulics

I had to remove DOT 5 from my TR3. Apple Hydraulics charged me for rebuilding my front calipers twice. Once the restoration was done and when the DOT 5 ran out of the caliper pistons adn kept the wires sprayed with oil. Apple said that the seals were not compatible with DOT 5. I did not have issues with the rear brakes suing the DOT 5 though, however the slaves were new.
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