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420A New clutch not disengaging all the way.

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Brad Bell

Proven Member
192
5
Aug 15, 2014
Levant, Maine
I just replaced my clutch on my 2g eclipse 420a with a stage 2 southbend clutch. Along with all new clutch components, throw out betting, clutch fork, slave and master cylinder. I bled the clutch for what seemed like forever and all I got was a soft pedal. I couldnt even get the car into to gear so I adjusted the master cylinder rod length to it's absolute maxi and I can just bsreba get it into gear. When driving, sometimes it will shift perfectly but sometimes I get stuck at a red light cause it literally won't go into first gear. The clutch also engages probably a half inch off the floor. I'm not sure what else could be causes this. I just ordered a new hydraulic hose that goes in line between the hard line hydraulics because I heard those can let air in the system if they are bad. There is no leaks anywhere and my clutch fluid does not go anywhere, never had to refill it. Maybe I am not bleeding correctly, I didn't stick the bleeder screw on the slave cylinder into a bottle of brake fluid, I heard those can let air back in the system as well while bleeding. Not sure what to do besides these two things. Any help is much appreciated. This is driving me crazy.
 
You either have air in your line, or you over-adjusted and are not filling up the master cylinder all the way.

You should have a disengagement range around 0-2" with a new SBC clutch, even with the modular clutch for your car.

Give this a try, loosen your clutch master cylinder rod lock nut, adjust the rod back into the pedal assembly several revolutions to take all the load off the master cylinder at full pedal-up, and make sure the piston fully moves to its full volume position. Then, you will start by pumping the pedal slowly for let's say, 20 times. Visually inspect that the piston is full out, and verify you have no fluid seepage around the outer piston seal of the master cylinder piston (there are two seals; inner and outer; if the inner seal is flawed/damaged it will have inconsistent pedal feel and potentially ghost pedal or pedal pump-up issues; if the outer piston seal is flawed/damaged it will have visual seepage at the dust boot if you pull it back).

Now that you have verified that the piston is able to do full movement and is hopefully full fluid volume, you will start the bleeding process several times.

Go grab some silicone tubing and some poly tubing (use the silicone tubing to put firmly on the bleeder fitting barb; and use the poly tubing sleeved inside the silicone tubing; then have the tubing running into 1 quart bottle -- 32oz; with at least a two foot length on the poly tubing so it can be easily done with one person.

With pedal UP, open slave bleeder valve, go and slowly push down the pedal to the floor.
Tighten bleeder valve.
Pull the pedal back to the UP position.
Open slave bleeder valve, and slowly push down the pedal to the floor.
Tighten bleeder valve.
Pull the pedal back to the UP position.

Do this protocol for like 3 or 4 times. Then with the pedal UP, manually adjust the slave cylinder adjustment rod until the rod contacts the master cylinder piston and there is no free play in the pedal at that spot. Tighten the lock nut.

You should have alot of adjustment range at the pedal to start doing the clutch adjustment process.

Start by pushing the pedal and seeing how it feels, then where the disengagement range is currently, then if the clutch is disengaging high or mid pedal, then adjust the master cylinder rod back into the pedal starting with 1 or 2 revolutions, and test again. If good, then stop and try with car running and see if it is consistent.

If the clutch is disengaging at the floor or not fully disengaging, then try adjusting the adjustment rod towards the master cylinder 1-2 revolutions and see again where the disengagement range is at.

Again, the SBC stuff should have about 0-2" of disengagement range off the floor when installed.

Your slave cylinder should have around 0.75"-1.00" of full range of motion for reference. If you are getting less than that, you likely have air in your lines/cylinders, or a master or slave that is flawed internally and needs a teardown to find the problem.

Give this a try!

Thanks,

Tim Zimmer
TMZ Performance
 
Did you torque the pressure plate bolts down properly? That actually matters alot.

Did you get the flywheel step height checked?

Check all the bell housing bolts and make sure they are in place / tight. Check to see if the transmission moves away from the block when you push the clutch.

Did you bench bleed the master cylinder properly? Air can get trapped in there that no ammount bleeding will get out if you didn't

I believe all these should apply to a 420a as they would a 4g63.

Edit: If sometimes the car goes into first perfectly at a dead stop, then you can probably ignore the step height / pressure plate torque comments and target a bleeding issue as twicks stated.
 
Last edited:
Did you torque the pressure plate bolts down properly? That actually matters alot.

Did you get the flywheel step height checked?

Check all the bell housing bolts and make sure they are in place / tight. Check to see if the transmission moves away from the block when you push the clutch.

Did you bench bleed the master cylinder properly? Air can get trapped in there that no ammount bleeding will get out if you didn't

I believe all these should apply to a 420a as they would a 4g63.

The OP has a 420a clutch, it is a modular clutch meaning that the clutch pressure plate, disk and flywheel are all as an assembled unit that get put onto the transmission first like a torque converter with 4 bolts, then it gets attached to the flexplate/ring gear that is already bolted to the crank with 6 bolts.

There is no flywheel step height to adjust or check. It is not like 4G63 flywheels.

The slave cylinder and master cylinder bleeding processes and adjustment processes are the same.

The 2G DSM 420A clutch slave cylinder OEM is M04670065 (04670065 mopar part number), or Exedy SC761. The OEM slave cylinder may be discontinued. There is no rebuild kit for the OEM slave cylinder for this application.
The 2G DSM 420a clutch master cylinder OEM is MB911650, or Exedy MC401. The rebuild kit for the OEM master cylinder is MB870511 for this application.
 
The OP has a 420a clutch, it is a modular clutch meaning that the clutch pressure plate, disk and flywheel are all as an assembled unit that get put onto the transmission first like a torque converter with 4 bolts, then it gets attached to the flexplate/ring gear that is already bolted to the crank with 6 bolts.

There is no flywheel step height to adjust or check. It is not like 4G63 flywheels.

The slave cylinder and master cylinder bleeding processes and adjustment processes are the same.

The 2G DSM 420A clutch slave cylinder OEM is M04670065 (04670065 mopar part number), or Exedy SC761. The OEM slave cylinder may be discontinued. There is no rebuild kit for the OEM slave cylinder for this application.
The 2G DSM 420a clutch master cylinder OEM is MB911650, or Exedy MC401. The rebuild kit for the OEM master cylinder is MB870511 for this application.

The more you know. I wasn't sure if it was the same so I probably shouldn't have posted.
 
Well, I am sort of an expert on the subject and I run a business rebuilding drivetrains and doing custom clutches for our application. And

Learning is sometimes done through reading or hands-on; just as long as you continue to learn, that is what matters!
 
Thank you all for your replies, it really just seems like there is air in the system somehow, I know its not my transmissions (synchros), because sometimes it shifts like butter, other times though I can't even get the car into first completely. I ordered that rubber clutch hose that goes in the hydraulic line today and should be here by this weekend so I can throw it in. Hopefully that and bleeding correctly should fix it. Ill let you know asap.
 
You either have air in your line, or you over-adjusted and are not filling up the master cylinder all the way.

You should have a disengagement range around 0-2" with a new SBC clutch, even with the modular clutch for your car.

Give this a try, loosen your clutch master cylinder rod lock nut, adjust the rod back into the pedal assembly several revolutions to take all the load off the master cylinder at full pedal-up, and make sure the piston fully moves to its full volume position. Then, you will start by pumping the pedal slowly for let's say, 20 times. Visually inspect that the piston is full out, and verify you have no fluid seepage around the outer piston seal of the master cylinder piston (there are two seals; inner and outer; if the inner seal is flawed/damaged it will have inconsistent pedal feel and potentially ghost pedal or pedal pump-up issues; if the outer piston seal is flawed/damaged it will have visual seepage at the dust boot if you pull it back).

Now that you have verified that the piston is able to do full movement and is hopefully full fluid volume, you will start the bleeding process several times.

Go grab some silicone tubing and some poly tubing (use the silicone tubing to put firmly on the bleeder fitting barb; and use the poly tubing sleeved inside the silicone tubing; then have the tubing running into 1 quart bottle -- 32oz; with at least a two foot length on the poly tubing so it can be easily done with one person.

With pedal UP, open slave bleeder valve, go and slowly push down the pedal to the floor.
Tighten bleeder valve.
Pull the pedal back to the UP position.
Open slave bleeder valve, and slowly push down the pedal to the floor.
Tighten bleeder valve.
Pull the pedal back to the UP position.

Do this protocol for like 3 or 4 times. Then with the pedal UP, manually adjust the slave cylinder adjustment rod until the rod contacts the master cylinder piston and there is no free play in the pedal at that spot. Tighten the lock nut.

You should have alot of adjustment range at the pedal to start doing the clutch adjustment process.

Start by pushing the pedal and seeing how it feels, then where the disengagement range is currently, then if the clutch is disengaging high or mid pedal, then adjust the master cylinder rod back into the pedal starting with 1 or 2 revolutions, and test again. If good, then stop and try with car running and see if it is consistent.

If the clutch is disengaging at the floor or not fully disengaging, then try adjusting the adjustment rod towards the master cylinder 1-2 revolutions and see again where the disengagement range is at.

Again, the SBC stuff should have about 0-2" of disengagement range off the floor when installed.

Your slave cylinder should have around 0.75"-1.00" of full range of motion for reference. If you are getting less than that, you likely have air in your lines/cylinders, or a master or slave that is flawed internally and needs a teardown to find the problem.

Give this a try!

Thanks,

Tim Zimmer
TMZ Performance

What do you mean by "full volume position" with the master cylinder? When I press the clutch in the rod goes into the cylinder and about a 1/4 inch still sticks out. It does not completely into the cylinder.
 
The master cylinder is composed of a fluid reservoir, cylinder, a piston, an inner and outer piston seal, a retainer clip (stopper for piston), the piston actuator rod (master cylinder adjustment rod), the clevis (the part that attaches to your pedal assembly) and a dust boot.

You want to make sure your piston has complete travel in the cylinder, and that it is not currently adjusted partially into the master cylinder when you were doing your initial installation, fluid filling and bleeding. Otherwise you are not going to fully fill the master cylinder to full fluid volume, especially when you have your adjustment rod all maxed out towards the master cylinder at pedal up. Adjust the rod back out so you can actuate the master to get the piston to move further out, then bleed to fill the chamber, and then do your adjustment.

Make sense?
 
The master cylinder is composed of a fluid reservoir, cylinder, a piston, an inner and outer piston seal, a retainer clip (stopper for piston), the piston actuator rod (master cylinder adjustment rod), the clevis (the part that attaches to your pedal assembly) and a dust boot.

You want to make sure your piston has complete travel in the cylinder, and that it is not currently adjusted partially into the master cylinder when you were doing your initial installation, fluid filling and bleeding. Otherwise you are not going to fully fill the master cylinder to full fluid volume, especially when you have your adjustment rod all maxed out towards the master cylinder at pedal up. Adjust the rod back out so you can actuate the master to get the piston to move further out, then bleed to fill the chamber, and then do your adjustment.

Make sense?
So what your saying I should back off on the "maxed out" position of the adjustment rod so there is some play in the pedal. Do the bleeding, and then make the adjustment again? That makes sense I just don't know how that would cause the madtee cylinder to push more fluid.
 
Yes, you should. Bleed it and CONFIRM you are getting full travel, and not just 75% of travel because the piston is starting out sitting a 1/4 the way in the cylinder already. You get that?

I have seen this enough over the last 20+ years of screwing with these cars and hydraulic clutch systems to deal with partial disengagment issues, over-extended rods causing fluid bypass or partial cylinder volume, and over-disengagment issues from over-adjustment, bandage fixes (longer slave rods, shimmed pivot balls, modified clevis, modified master cylinder rods, etc.

As well, if you are using a crappy cheap parts store master or slave cylinder, you also may be dealing with a part that is not working 100% even if it is brand new. It happens, I am just saying so you know.
 
Yes, you should. Bleed it and CONFIRM you are getting full travel, and not just 75% of travel because the piston is starting out sitting a 1/4 the way in the cylinder already. You get that?

I have seen this enough over the last 20+ years of screwing with these cars and hydraulic clutch systems to deal with partial disengagment issues, over-extended rods causing fluid bypass or partial cylinder volume, and over-disengagment issues from over-adjustment, bandage fixes (longer slave rods, shimmed pivot balls, modified clevis, modified master cylinder rods, etc.

As well, if you are using a crappy cheap parts store master or slave cylinder, you also may be dealing with a part that is not working 100% even if it is brand new. It happens, I am just saying so you know.
Alright yeah that makes sense. Thanks so much for your input, you seem to have a lot of experience. Ill do that and get back to you.
 
Yes, you should. Bleed it and CONFIRM you are getting full travel, and not just 75% of travel because the piston is starting out sitting a 1/4 the way in the cylinder already. You get that?

I have seen this enough over the last 20+ years of screwing with these cars and hydraulic clutch systems to deal with partial disengagment issues, over-extended rods causing fluid bypass or partial cylinder volume, and over-disengagment issues from over-adjustment, bandage fixes (longer slave rods, shimmed pivot balls, modified clevis, modified master cylinder rods, etc.

As well, if you are using a crappy cheap parts store master or slave cylinder, you also may be dealing with a part that is not working 100% even if it is brand new. It happens, I am just saying so you know.
Okay so did everything you said and still nothing. The only way I can possibly get into gear is if I have the adustment rod on the master cylinder way maxed out. And even with it maxed out it isn't smooth. I bled the hell out of it today untill zero air bubbles, adjusted the rod, and nothing. Pedal feels decent, there is definitely pressure. I am stumped I have no idea what to do haha.
 
hmmmm, are these OEM or aftermarket clutch master and slave?
 
hmmmm, are these OEM or aftermarket clutch master and slave?
They are aftermarket. Also I found on other forms that possibly the master cylinder may possibly have an air bubble trapped in it. I did not bench bleed either master or slave. So I'm thinking if I press and hold the clutch pedal down and crack the line that goes into the master cylinder I can get more air out of the system.
 
Ok give it a shot. Alot of aftermarket ones are remanufactured or poor tolerances, or have faulty seals right out of the box. I have had the best luck with exedy brand replacement master and slave cylinders, both of which I stock for 420a and 4g63 applications.
 
Ok give it a shot. Alot of aftermarket ones are remanufactured or poor tolerances, or have faulty seals right out of the box. I have had the best luck with exedy brand replacement master and slave cylinders, both of which I stock for 420a and 4g63 applications.
Alright I think I am going to guy buy a new set of master and slave cylinders. I bought my other set from Rock Auto for a cheap price so I'm thinking those just may be bad. Rebleed the entire system and see what happens. I'll keep you posted.
 
Give yours a shot first of course.

Just PM me.
 
Give yours a shot first of course.

Just PM me.
Alright bleeding the master didn't do anything haha. So I'm on my way to pickup a good master and slave cylinder. Hopefully that fixes it, do you have any tips for brand new master and slave cylinder parts? Should I bench bleed any of them before installing? Bleeding techniques?
 
fill it up and bench bleed it with fresh fluid. Attach a braided line between them and make your own sealed system, it will work out easy, then install it in the car and it should be easier to finish bleeding / adjustment stuff.

Also take a close look at your clutch pedal assembly for wear point issues (the pivot bushings).
 
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