I've been helping a buddy with his hot-rodded Miata. It has a 215 Buick engine and a T5 transmission. We've installed a RAM hydraulic throwout bearing and it won't release the clutch. There are a couple of holes in the bell housing where I can see the bearing and I'm able to push it back until it's fully compressed. At that point it's got roughly 3/16" clearance between the bearing face and the fingers of the clutch. To me, who has no experience with this stuff, this is too much and should be next to no clearance. What say the members of the hive?
Bearing should just/almost touch the fingers. Probably out of travel before it I even hits the fingers.
https://grassrootsmotorsports.com/forum/grm/hydraulic-throwout-bearing-questions-gm-t5-related/130872/page1/
The clearance might need to be tighter, see the instruction sheet for the throwout bearing being used.
EDIT: Also, are you sure it's been bled properly?
In reply to Ranger50:
That's kinda what I was thinking. With a full stroke of the clutch pedal the bearing expands about 0.410", so it's contacting the fingers but certainly not getting the full benefit.
In reply to DeadSkunk:
If you are pushing it back and get ~3/16" that is about right as the fingers will move toward the gearbox as the clutch disc wears. Let the hydraulics do their thing and press the pedal, release. It should leave the throwout bearing up next to the fingers. Then the next time you push the pedal it does not have to start from so far away.
Worst case, you have to shim the pivot/slave cylinder to make up the gap.
In reply to stafford1500:
I'll have to try the clutch myself and see if pumping it twice will allow it to release. This all makes sense , but it wasn't working for him. I want to figure out what might be wrong before we go nuts and rip it all out to start over.
DeadSkunk wrote:
In reply to Ranger50:
That's kinda what I was thinking. With a full stroke of the clutch pedal the bearing expands about 0.410", so it's contacting the fingers but certainly not getting the full benefit.
That seems like an awfully short stroke. It takes about .5" of pushing on the clutch fingers to fully release a sprung clutch (on the few that I have measured).
I wouldn't be surprised if the clutch master "rod" is already engaged in the master cylinder too far which is reducing the effective stroke.
Also, I would be bleeding the crap out of that thing about 3 different ways.
We had to on our T5 equipped RX7 (behind a GM 3400 engine). It seemed like it released, but it was not enough.
I had to push fluid one way, vacuum it the other, and manually pump and bleed this thing until it was right.
The hydraulic axial slave that I installed on a customer's car last fall had to be shimmed out to .150" clearance plus or minus a small tolerance.
In reply to Knurled:
This one says .150-.200 in the instructions, so we may have to go closer to the .150.
video here.
Ram has videos on youtube that tell you exactly what it should be and how to measure it.
Unfortunatly, I do NOT think you can measure it installed.
In reply to wvumtnbkr:
We'll check that today. We installed a brand new Wilwood master cylinder. I don't think he had to push the rod in to get it to fasten to the clutch lever, but I don't know for sure. I'll check that.
In reply to wvumtnbkr:
Bleeding will be first on the list to try this morning, since it's the easiest to start with.
