[Leo41]

Hey guys, as some of you know from my post in the general section I am having some hydraulic issues with my clutch (sticking to floor at times under aggressive shifting), and I am swapping to a McLeod stainless line and adding the Steeda assist spring. I also want to flush the fluid and that is where I am having trouble.

I tried to call a few Ford dealers as I want to do a BG ultra dry DOT 4 flush (normal BG flush done on just about every car out there). Both dealers I talk to tell me they use BG, but waffle when asked directly my question. One worthless serv writer tells me they don't do brake flushes on GT's unless they are automatics (WTF), the other I talk to the shop foreman, and worth noting this guy has a great reputation around town.

I have to say he took a lot of time with me. He says they avoid doing the clutch portion when doing a brake flush (how awful is that), and that they would only use DOT 3 in the car. Now he agreed DOT 4 is better, and replaces but fell back on they would use DOT 3 because that is what Ford says. Then again he also says he hasn't really heard of Mustang clutches sticking to the floor... uggghh. He starts going down the symptoms list for the nearest complaint to that listed and of course mentions nothing hydraulic, only mechanical, then of course he agrees with me the issues does in fact sound hydraulic... round and round.

So.. guys, what are you or have you done for brake/clutch fluid? Have you gone to DOT 4 or stayed with 3? Have you ever flushed the system?

 

[noldevin]

I am full DOT4 due to road course usage.
That being said, DOT4 most likely won't fix your clutch issues. I'd try pulling your assist spring, but if that doesn't work then it's probably a pressure plate issue.

I did notice a slight improvement in clutch pedal feel when i swapped the fluid, but i think the importance is more just that it is fresh fluid, and not that it has to be 100% pure DOT4. It will be hard to get ALL the fluid out of the clutch cylinders since they are self-bleeding.

 

[MustangLife]

The clutch pedal sticking to the floor under aggressive shits appears from what I found to be a VERY COMMON problem. The dealer I took my Boss to completely agreed. I put the Mcleod clutch line in and then actually replaced the clutch under warranty and haven't had any issues of that since. *knock on wood*. I am not 100% sure the clutch needed to be replaced that is what they wanted to do. I had read the line fixes it so I had them put that in during clutch install.

Noting wrong with going with DOT 4 in replace of DOT 3, but I don't think this will change your problem any. From my understand and you might want to confirm this, but it is safe for DOT 4 to mix with DOT 3 just if it calls for DOT 3 you can use either. If it calls for DOT 4 you can only use DOT 4. NEVER mix either with DOT 5. Again confirm all this as it is just what I am recalling when I researched the matter a while back.

 

[Leo41]

I am full DOT4 due to road course usage.
That being said, DOT4 most likely won't fix your clutch issues. I'd try pulling your assist spring, but if that doesn't work then it's probably a pressure plate issue.

I did notice a slight improvement in clutch pedal feel when i swapped the fluid, but i think the importance is more just that it is fresh fluid, and not that it has to be 100% pure DOT4. It will be hard to get ALL the fluid out of the clutch cylinders since they are self-bleeding.

Sounds good, see I just want to go to DOT 4 understanding it will not help the clutch feel or anything but I'm trying to be sure it won't mess anything up.

 

[noldevin]

DOT4 will not mess anything up but does need to be flushed more often due to collecting moisture faster than DOT3

 

[Leo41]

The clutch pedal sticking to the floor under aggressive shits appears from what I found to be a VERY COMMON problem. The dealer I took my Boss to completely agreed. I put the Mcleod clutch line in and then actually replaced the clutch under warranty and haven't had any issues of that since. *knock on wood*. I am not 100% sure the clutch needed to be replaced that is what they wanted to do. I had read the line fixes it so I had them put that in during clutch install.

Noting wrong with going with DOT 4 in replace of DOT 3, but I don't think this will change your problem any. From my understand and you might want to confirm this, but it is safe for DOT 4 to mix with DOT 3 just if it calls for DOT 3 you can use either. If it calls for DOT 4 you can only use DOT 4. NEVER mix either with DOT 5. Again confirm all this as it is just what I am recalling when I researched the matter a while back.

In going through tons of old threads I did see a few cases where the clutch was replaced because of this, but even more where the spring and/or the line fixed it completely. I figure I want the best clutch possible so I'll start here, replace the clutch later if needed it just does not feel clutch/pressure plate. As I was telling David (the shop foreman guy) this morning mechanically there feels like there is nothing wrong, it is just a flat loss of hydraulic pressure.. the pedal goes soft.

Ok.. good good both of you running DOT 4 with no problems.

 

[Leo41]

DOT4 will not mess anything up but does need to be flushed more often due to collecting moisture faster than DOT3

No problem there as I will be flushing every 2 years like clockwork.

 

[dusman59]

Dot 5.1 works for me. Zero clutch problems with stock line and spring to redline shifts. Not saying 5.1 is the fix for problem clutch not returning. I don't track which would require flushing often. 5.1 for street is 2 years. Dot 4 is one year. With the high AZ temps I wanted better brake fluid. I use it in my DD as well.

 

[Leo41]

Dot 5.1 works for me. Zero clutch problems with stock line and spring to redline shifts. Not saying 5.1 is the fix for problem clutch not returning. I don't track which would require flushing often. 5.1 for street is 2 years. Dot 4 is one year. With the high AZ temps I wanted better brake fluid. I use it in my DD as well.

DOT 4 usually was 2 years on most cars I dealt with, but better safe than sorry as it ties the clutch in too, seeing you are not the first one to say 1 yr on DOT 4.

BTW... how do you like your 3.55 gears? I am running the stock 3.31 which I do like but DD'ing the car I'm thinking with a little more gear 6th would be more usable. Most of my local running around is in the 50 mph range which means I am either at 2400rpm in 5th or a (too low for my taste) 1400-1500 rpm in 6th.

 

[XRacer]

Federal law requires that the various grades of brake fluid be compatible so changing to DOT 4 won't be a problem. This federally mandated compatibility is a good thing since in order to avoid any possibility of contamination from the previously used fluid would require replacing the entire brake system and the hydraulic throw out bearing [ otherwise known as the clutch slave cylinder ] with all new parts. Some amount of old fluid will always be present after flushing. OK, if anyone wants to pick nits, I suppose you could flush the system with alcohol before adding the new and different fluid. Good luck with the throw out bearing. Ford seems to be a bit confused regarding what to use. The master cylinder cap says to use DOT 3, my owners manual calls for DOT 4. The dealers seem to prefer DOT 3. The only way I can see the hydraulic clutch system causing the pedal hang up would be if there is a some sort of restriction in the line or a defective throw out bearing. Pushing the pedal down would generate enough pressure to overcome a minor restriction, but if the fluid can't return unrestricted when the pedal is released it MIGHT cause the pedal to hang up. Generally when a clutch pedal hangs up at high rpm it's due to the pressure plate. Diaphragm type clutches have had issues with this for over half a century. At 73 I am old enough to remember when Chevy guys in the '50's & '60's would replace their Chevy diaphragm clutches [ they really were crap ] with Chrysler Borg & Beck style clutches since they used the same bolt pattern and the Mopar clutches were pretty darn good for a factory clutch. Most modern diaphragm clutches, both factory and aftermarket seem to work pretty well. I use a Sachs diaphragm in my '72 'Cuda and I've never had any problems with it. Of course being an old classic it has a mechanical pedal linkage. The rather stiff clutch assist spring COULD possibly be the culprit or at least contribute to the problem. That said, I never had any problem with mine. The main reason I went with the Steeda spring was for the better feel. The best rear axle ratio depends on how the car is used. For a 1/4 mile drag racer using larger than stock diameter rear tires the 3.73 would be best so long as you can still reach the finish line in 4 th. and avoid the final shift into 5 th. On a tight road course or autocross with short straights, 3.73's would still be good. Longer straights and 3.55's or 3.31's are the way to go. IMO the 3.55's are the "Goldilocks" choice. There is a big difference between 3.73's and 3.31's, not so much when going from one of them to 3.55. I have the standard 3.31's in my '14 GT and I wouldn't bother changing them to 3.55's for the minor difference involved unless I found a complete low mileage rear end somewhere for a killer price.