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Mcleod Hydraulic Clutch issues "losing pedal pressure while driving"

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mdavidthomas

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Discussion starter · #1 ·
I am using the Mcleod hydraulic clutch conversion kit for 67-69 Camaros. I recently was able to get the car fired up and I have taken a couple of trips around the block. I have been having issues shifting into first gear when trying to shift while slow rolling in a parking lot. I assumed it was either a bad synchro or the clutch not releasing when pressing the hydraulic clutch system. Yesterday, I used a mityvac and was able to get all the air out of the system, I think. I had good pedal pressure and it seemed to go into gear easier when at a stop; however, the first time I tried to shift when rolling at slow speeds the transmission grinded again but when at a full stop it goes into gear with no issues. So, I took it for a 25 min drive to get some HP tuner data. After about 20 mins, I noticed when at a stop it started slightly grinding into first and the pedal release seemed to be getting closer to the floor. I do not seem to be losing any clutch hydraulic fluid but I am losing pedal pressure. The only thing I can think of is a damaged seal in the clutch master cylinder. Any thoughts?

Thanks
 
#2 ·
Sounds like you have not yet gotten all the air out of the system. McLeod uses the Wilwood compact MC. Yeah like any part maybe it itself is faulty but given this is the first use, I suspect air due to incomplete bleeding.

Does your setup have a speed bleeder near the T.O. bearing?
 
Discussion starter · #3 ·
SoCal805 said:
Sounds like you have not yet gotten all the air out of the system. McLeod uses the Wilwood compact MC. Yeah like any part maybe it itself is faulty but given this is the first use, I suspect air due to incomplete bleeding.

Does your setup have a speed bleeder near the T.O. bearing?
Click to expand...
I have the tick speed bleeder extended up to the Reservoir. I went for a ride today and I started off with a pretty good pedal and the trans would shift into first even while rolling. However, as the vehicle heated up and the further I drove it started grinding when rolling in a parking lot a low speeds (<5mph) but would shift into gear at a dead stop. Also, reverse is always hard to get into gear and never feels as if it is fully engaged.
 
#4 ·
Hard to get into first and reverse means clutch is not disengaging completely. Typically due to hydraulics needing bleeding or there is not enough travel in the TO bearing because too much gap (need more shim).

If pedal feels firm...you sure gap was set right?
 
Discussion starter · #5 ·
Here is a video of the air bubbles that come out of the system. I have a plug with vacuum down in the reservoir with about 20 in of HG. Nothing comes out until I press the clutch then I get some bubbles. If I put the vacuum hose on the speed bleeder, I get nothing unless I press the clutch. (i.e. no fluid, no bubbles). It seems as if there is no leak in the system because I see no fluid and the vacuum stays constant on the gauge.


1969 Camaro Mcleod clutch bleeding
 
Discussion starter · #6 ·
Just an Update. I let the vacuum stay on the reservoir line overnight and this morning I started pumping the pedal and a bubble started coming out on every pump. After 50 or so pumps, I decided to release the vacuum and try to put the tick speedbleeder into the reservoir to see if I get any air bubbles out. I did not see any bubbles come from the speedbleeder and pumping the clutch at least 50 times. I currently have a good pedal feel but I have nothing to compare it against. My thought is the vacuum is pulling air past the cup seal in the master cylinder which is why I see air bubbles almost continuously with vacuum applied to the reservoir side of the master cylinder. I will try to drive it today and report back but my gut is telling me after a 15+ min drive, I will either lose my clutch (i.e. the engagement point will get closer and closer to the floor) or 1st gear will start grinding at a slow roll and maybe when at dead stop.

Thanks for any and all input.
 
#8 ·
Jack rear of car up. Both wheels off ground( jack stands) have the car running and put car in gear. Then slowly let the clutch out and see where the clutch grabs. If high off the floor air is not ur problem.
Syncros in a trans are tapered. They when u shift, put pressure on the gear and cause it to stop spinning. Then u can smoothly put it into gear. If it’s too loose (worn) the gear keeps spinning and grinds when you put it into gear.
The slower you shift gives the gear more time to stop spinning. Once car is hot let the clutch out. See where it grabs.
 
Discussion starter · #9 ·
Here is my setup:

TR6060 with LUK clutch and pressure plate for a Corvette Z06
LUK Slave Cylinder for a 2013 Camaro SS with TR6060
Mcleod 67-69 Camaro hydraulic clutch kit
Tick Speedbleeder line kit

I spoke with Billy @ Mcleod Racing today and he said that if my clutch lines run close by a heat source (i.e. headers) that I may be boiling the clutch fluid causing it to turn into a vapor. When cold I do leave with a higher clutch engagement point than after a 15 minute drive. He recommended Wilwood EXP600 Dot 4 brake fluid and DEI heat sleeves. My clutch lines do run within 2-3" of my #7 header primary and over top the collector area before entering the bellhousing.

I did jack the front of the car up to get the try and help get the air out of the master cylinder when bleeding with vacuum.

He also told me that 20" of Hg was too much and may roll the seal out of the groove in the master cylinder piston. I am not sure this has happened but I do think it is possible to pull air past the o-ring or cup seal with too much vacuum on the system.

I originally used a lift and checked that my tires stopped spinning when pressing the clutch in and checked where the clutch grabbed. While I remember it being closer to the floor than I had hoped for it seemed to be ok. I can try the engagement point when cold and hot to see if there is a change.
 
Discussion starter · #10 ·
Yesterday afternoon, I decided to flush the system again with new DOT 3 fluid because I have had the system open a lot and I have seen something in the fluid that looks like white particles. So, I pumped the clutch until the fluid was just at the bottom of the reservoir and kept adding fluid until I had flushed the system through two reservoir's of fluid. I original had my mighty vac on the speedbleeder end but could not get much fluid out. It almost felt as if there was some kind of restriction in the system but since I was doing it by myself I couldn't really watch the bleeding while pumping the pressing the clutch pedal. At some point, I placed a container on the floor and put the speed bleeder by the door so I could see and when it was pumping the fluid out. When the system started pumping a constant amount of fluid with no bubbles, I closed the system. I was able to drive the car last night and I never lost the pedal feel but I still get some grinding when trying to downshift to first at slow speeds. I also tried waiting longer between pressing in the clutch and shifting into first and it seemed to work. This may point to a bad/worn synchro in first gear.
 
#11 ·
Billy has some good points about heat insulation given the routing of your line close to headers. Vibrant Performance makes a split tube heat sleeve, so you don't need to break lines apart to slide it on. Comes in various widths in 4" lengths. Summit has it

Yes it is possible given the vacuum pressure, 20, you rolled the seal out.
 
Discussion starter · #13 ·
Update: I decided to flush the hydraulic system one more time and I started by putting vacuum 10" of Hg on the speedbleeder but it did not pull anything out of the system. So, I took a bottle and dropped the speedbleeder into it on the floor and it seemed as if nothing was going to come out at first and finally I am pretty sure some air came out and I flushed the system with two reservoir's full of Dot 3 fluid. I feel like there may have been blockage in the system. Regardless, I can now shift into first and I am holding pressure on the pedal. I do still get grinding if I am rolling and downshift from second to first immediately. If I give it time between shifts I can normally shift into first without any grinding. Maybe synchros in first? I did buy the wilwood DOT 4 and some DEI heat reflective shielding.

Thanks for the feedback,
 
#14 ·
Is your MC rod adjustable?

Do you have a pedal stop on clutch pedal?

Have you raised the rear end off ground, car secure on jack stands, started car, put in 1st gear and hold clutch down...do rear tires move?

What trans fluid?
 
Discussion starter · #18 ·
Currently using Royal Purple Synchromax for manual transmissions. Did some research and some people have been running it. Could switch to the GM version for it. Finally, flushed the system with the Wilwood EXP600 with the DEI heat wrap but I don't have enough drive time to tell if it has helped.
 
#19 ·
mdavidthomas said:
Currently using Royal Purple Synchromax for manual transmissions. Did some research and some people have been running it. Could switch to the GM version for it. Finally, flushed the system with the Wilwood EXP600 with the DEI heat wrap but I don't have enough drive time to tell if it has helped.
Click to expand...
Old school 4 speeds need gl4 gear oil. It’s thicker and stickier. If everything is too slick the synchro can’t work.
anything with brass in it get the old school gl4.
 
Discussion starter · #20 ·
Tremec recommends Dextron III in the T56 Magnum/TR6060 transmissions. The Gen 5 Camaro owner's manual states use GM part number 88861800 which is for Manual transimissions and transfer cases.

I also see people recommending Royal Purple Synchromax, Redline ATF D4, and Amsoil ATF Torquedrive. 🤷‍♂️

I am planning to use the Dot4 with heat wrap on the hydraulic lines to see if this helps first but I am not beyond changing fluids.

Anyone on here using Royal Purple Synchromax on a TR6060?

Thanks,
 
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mdavidthomas
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