blownmiata

I am afraid that I pulled a real bonehead move. While putting together my LS1/T56, I bought an LS7 clutch, a brand new flywheel and hydraulic clutch slave cylinder. As I recall, the slave, flywheel and clutch assembly bolted up nice, and the trans shaft slid into place.

The problem is, after bleeding the system, the clutch doesn't disengage. I am wondering if I failed to buy and assemble some critical piece (pilot bearing? throwout bearing?). The clutch did not come with an alignment tool, which I thought was strange, but maybe that comes with one of these bearings that I didn't buy. Please don't tell me that I need to drop the engine and remover the trans to resolve my stupidity.

bczee

iTrader: (12)

can you inspect or watch the throwout bearing as someone steps on the clutch pedal ?

Using a mirror or tv scope.. ?.. and see if the throwout bearing is engaging the clutch arms ?

Yes, you should have or need a pilot bearing in the crank. Not all Clutch manufactors ship there clutches with alignment tools.. I just use an old input shaft or buy a Clutch Alignment tool.. they are pertty cheap anyways and you can always use it on almost all cars.

I would think that if you were able to slide the Trans in, all sould be ok!? see if you can check to make sure the Throwout bearing is really engaging the Clutch and is traveling enough to dis-engage the clutch !?

Keep us posted !

GlennNo50

Did you actually put a throwout bearing in it. Mine came with my new slave but it's possible yours didn't. The picture below shows the 2 separated. Throwout is on the left in the first picture. Assembled in the second picture.

mmmchickenboy

If you don't have a pilot bearing in the crank, you have to pull the tranny regardless of anything else.

alocker

iTrader: (10)

Im guessing you dont have a pilot bearing installed. There is no way you could install the trans without a clutch alignment tool if the bearing was installed.

Second-Something else is wrong if your not dis-engaging the clutch. Im afraid you will have to tear it apart.

blownmiata

my slave was like the one on the right, so I must have the throwout bearing. I do not recall installing any other (pilot) bearing, and the trans shaft went in without any problem. So I need to find a pilot bearing and take the transmission off?

What else could be wrong to prevent the clutch from disengaging? We have bled it several times, and the pedal pressure is quite firm.

LS1-450

iTrader: (33)

What did you use for a clutch master cylinder? Could be that the master isn't displacing enough oil. A 0.75" bore is best; Wilwood adjustable clutch master. I've seen a lot of Miata guys try a 0.625" bore or even a stock Miata master. They don't displace enough oil for the GM slave. You're gonna have to pull the tranny & install the pilot bearing as well.

blownmiata

I went back and checked my shopping list - I installed a complete slave cylinder assembly (with throwout), and I am using a Wilwood 3/4" master cylinder with a braided line. I bought an LS7 clutch kit LS2 Y-body flywheel from SpeedInc.

Sounds like my problem is the (lack of) pilot bearing? Would this be the cause of it not disengaging, or is there something else going on?

bczee

iTrader: (12)

as far as the pilot bearing, lets step back and ask where did you get the engine from ?.. was it a A4 or M6 car/truck...

If it as a A4 car, there would not be a pilot bearing in the end of the crank by default. If it was a Crate engine, same think, doesn't ship with one install.

If it cam from a M6, it should have one unless someone took it out.

stealth71

iTrader: (15)

The clutch not disengaging has nothing to do with the pilot bearing. Two separate issues. Are you sure the clutch is really bled. I had to bleed mine several times before the pedal get hard and the clutch was actually moving. Sounds like there still might be air in the line.

LS1-450

iTrader: (33)

As noted above, the pilot bearing is a completely different issue. Since you have to pull the tranny, clutch & flywheel anyway, should definately have the pressure plate/ flywheel assembly balanced (if not done).


Did you use the shim behind the throwout bearing? It's not always needed, but, seems like it was in your case. I have no trouble w/ my spec 3+ to T-56 assembly. Different clutch pressure plates have different dimensions, as well. Did you use a stock bell housing? Sounds to me like there is a dimesnional issue w/ your set-up. When you take it out, pull the tranny back an 1/8" or so & look to see if there is a gap between your slave & pressure plate. If you used the spring on the slave/throwout assembly, there will not be a gap between the slave & the pressure plate.


Once removed, check the flywheel to pressure plate finger dimension, the retracted slave cylinder dimension, the slave cylinder shim & the flywheel thickness (where is mounts to the crank shaft, add them up. Then measure from the splined end (not including the small diameter that sticks out for the pilot bearing) to the slave cylinder mount on the front of the tranny. These dimensions should be close. Then measure from the slave cylinder mounting surface to the end of the bell housing. Use the numbers to determine if the splined shaft location ends up just ahead of the crank shaft when the bell housing is bolted up.

Anyway, sounds like a lot, but it isn't. What is meant is to look @ the assembly as you remove the tranny & you will find the dimensional problem. Swaps aren't always assembled the same as a stock application. So, maybe you did something to change the slave cylinder to pressure plate relationship.

blownmiata

My LS1 is a rebuilt engine out of a firebird, and I used a stock bellhousing with no shim behind the hydraulic cylinder. We have bled the line a couple times, and the pedal pressure is quite firm. We are in the process of dropping the engine/trans, as we can't get to the bellhousing bolts when mounted.

Russ_B_10

iTrader: (3)

Any chance you put the clutch disk in backwards?

blownmiata

I think the clutch is made so that will only go one way.

Another thought - I wonder if adjusting the position of the threaded rod between the master cylinder and the clutch pedal might make a difference. If it was too far out or too far in, you would not get a full stroke. I will see if I can adjust this...

LS1-450

iTrader: (33)

Yes, that is the adjustment on the adjustable master cylinder. Back the rod out of the pedal hole (toward the master) until you feel resistance, then the cylinder is pretty much adjusted.

Pop N Wood

iTrader: (1)

Just went through all of this on my build. My HTOB needed two shims to ensure the proper clearance between it and my LS7 clutch. Then I had to adjust the clutch pedal clevis to get get enough stroke for the clutch to fully disengage.

BTW, I actually over extended the first HTOB. It is only once I ordered a replacement HTOB that I got an instruction sheet telling me how to measure for the clearance. I needed a half inch of shims. I had a Keisler unit, so not the same as yours.