1G OEM vs Aftermarket: clutch master and slave cylinder

[kilo4]

I've been having clutch disengagement problems for some time. I've pretty much replaced the entire drive train. Every parts listed below has than 200 miles. I finally gave up and replaced the after market clutch master and slave cylinder. I figured it must be good, since it's lifetime warranty. I took it apart and compared it to the OEM parts I received from STM. The OEM parts in the photo is from a used OEM part but it's exactly the same dimensions from the new unit I received from STM. I was surprised to see the difference, see the attached photo's. The master cylinder was purchased at Vaca autoparts (made in Japan) and the slave was purchased at Autozone (made in Taiwan).

Problem:
Hard to shift from 1st to 2nd gear above 3K rpm, hard to go in 5th and reverse gear

Solution:
replaced after market clutch master and slave cylinder. Also installed the SPEED BLEEDER 10 x 1.0 mm from Summit Racing part# RUS-639560 (made bleeding a breeze) = 100 % air free

Parts replaced:
- Jacks tranny w/transfer case
- Sheptrans pedal assy
- OEM shift cables
- STM shifter bearings
- OEM shift bracket bushings
- rebuilt OEM tranny cable select assy (bushings and pad)
- bushings under shifter plate assy
- OEM tranny fluid
- After market clutch master cylinder (at first)
- After market clutch slave (at first)
- rebuilt drive shaft (might as well)
- switched to 4 bolt rear with rebuilt axles (might as well)

1st Photo:
- Aftermarket master cylinder left--OEM on right

2nd Photo:
- master cylinder internals aftermarket on left and OEM on right
- notice the difference on the seal location (about 10 mm further back, therfore the aftermarket pushes smaller volume

3rd Photo:
- aftermarket master cylinder adjustment rod lenght (71.35 mm)

4th Photo:
- OEM master cylinder adjustment rod lenght (71.92 mm)

5th Photo:
- OEM slave (top)
- aftermarket slave (bottom) = *same diameter, different springs, different design but close

 

[2GeNTSi]

I was just thinking about replacing my master cylinder as well. I picked up one from O'reilly back in October '10 after my rebuilt OEM one started to leak after about 6 years, it has a lifetime warranty as well so I figured it would be okay. From day one I've had issues with it, sometimes the pedal would be too firm, and other times it would be normal (it never is consistent or predictable).

I've adjusted it to the suggestions of those on the forums (just enough so that the slave pushes in without too much effort), but the rod is almost completely screwed into the pedal assembly which I don't think is right. I recall comparing the two and the rod seemed just about the same length so I don't it's different in that sense. I believe it might be the piston and spring itself that is not as good as a design as the OEM which is in turn causing me to have these issues.

Have you seen a difference so far in the engagement and pedal pressure?

 

[kilo4]

Before this aftermarket was a rebuilt kit for my OEM master cylinder that failed with in 4 months. The rebuild kit would bleed pressure with pedal held to the floor. It was difficult to visually see the bleed down but it was enough to cause issues. Basically, I had a buddy hold the clutch pedal to the floor, and I attached a dial indicator on the clutch fork/tranny. The bleed down was clear with the dial indicator. You would think I learned my lesson and buy OEM, but instead I purchase new aftermarket.

I had low engagement issues with the after market master cylinder. The clutch engaged in less than 1" off the floor. After comparing the two units, it made sense due to the piston design (see pics above). I'm not saying all after market master cylinders have the same design. This particular brand was designed this way.

Your issue seems to be more like "air in the system" because of the inconsistency. Before spending $250, I would try installing a $14 speed bleeder from Summit and bleed it with a clear hose. See if that makes any difference.

 

[RoasT BeeF]

This is pretty good info. Thanks for sharing.

 

[kilo4]

Everyone always recommended OEM but no hard data. I'm hoping this would help others having clutch issues. I've had clutch issues since I purchased my car. So finally my car shifts perfectly.

Here's a list of my "Lesson Learned"
*1. Good pedal assembly (1G)
*2. OEM master and slave cylinder
*3. Properly bled clutch (speedbleeder help)
4. Steel braided hose to slave
*5. Properly shimmed pivot ball (close as possible to my clutch cover)
6. Correct flywheel step height
7. Serviceable clutch assembly
8. Serviceable transmission

*indicates critical steps for proper clutch engagement/adjustment

This is what it took to resolve my clutch engagement issues. Like I stated before, this post was meant to provide some ideas to others experiencing the similar issues.

 

[GsxEcutioner]

Bump for a question. Seeing that the Internals of the Master and Slave are the only things different from the Kragen/Autozone/Oreilly parts, does this mean that I can get a OEM Rebuild kit for each Master/Slave cylinder instead of buying a whole new unit? Please correct me if I am wrong, but the OEM Rebuild kits come with a new piston, clip, Rod and all that for the master cylinder correct? and same goes for the slave? Thanks for anyone that can help me right now in solving this stupid disengagement issue
-Shane

 

[bertrenolds]

After reading about a few people that have rebuilt their master and slave only to have them fail a few months later I would suggest that you just get a new master and slave. Orilies has the master for $21 and autozone has a slave for $14 so they are cheap enough that rebuilding makes no sense. The stuff is made in china so that sucks but maybe it is still better then a rebuild.

 

[GsxEcutioner]

After reading about a few people that have rebuilt their master and slave only to have them fail a few months later I would suggest that you just get a new master and slave. Orilies has the master for $21 and autozone has a slave for $14 so they are cheap enough that rebuilding makes no sense. The stuff is made in china so that sucks but maybe it is still better then a rebuild.

I am always on the last thread of the master with clutch drag, and slave is using a extended rod now. Overall I've had three slaves on the car and three masters. All were aftermarket and I want to know since I've read this thread if a oem rebuild kit would work for me.
-shane

 

[9!'clipseDOHC]

After reading about a few people that have rebuilt their master and slave only to have them fail a few months later I would suggest that you just get a new master and slave. Orilies has the master for $21 and autozone has a slave for $14 so they are cheap enough that rebuilding makes no sense. The stuff is made in china so that sucks but maybe it is still better then a rebuild.

Did you not read the thread at all? The whole point of it was that the OEM and parts store parts are different and the parts store parts are inferior in the way they perform. In the very same thread, here you are telling the guy asking about an OEM rebuild to buy a parts store part to save money?

GsxEcutioner, are you asking about rebuilding a parts store unit with an OEM rebuild kit? If that is the case, I personally would just go with new OEM part. I have never rebuilt my slave or master so take that in to consideration.

 

[bertrenolds]

I was replying more to GSXExicutioner so sorry. I was just letting him know that after reading several threads about rebuild kits and having them fail 4 months later it would probably be better to get an aftermarket master and slave then to rebuild even and OEM part. And I did read the OP comments and yes paying through the teeth at the stealership for a new OEM master/slave seems like the best route but who has money for that these days? It seems that the only 2 real differences are the price and the rod is a little shorter on an aftermarket master, as long as your clutch fully disengadges does it really matter?

I was going to suggest the longer slave rod to make up the difference http://www.maperformance.com/dsm-extended-clutch-slave-cylinder-rod-ex.-clutch-slave-rod.html but apparently it is a band aid.

9!'clipseDOHC, I was just saying that a POS after market master and slave would at least be better then a rebuild.

 

[GsxEcutioner]

I was replying more to GSXExicutioner so sorry. I was just letting him know that after reading several threads about rebuild kits and having them fail 4 months later it would probably be better to get an aftermarket master and slave then to rebuild even and OEM part. And I did read the OP comments and yes paying through the teeth at the stealership for a new OEM master/slave seems like the best route but who has money for that these days? It seems that the only 2 real differences are the price and the rod is shorter on an aftermarket master and since you can buy a new longer slave rod and put it in your aftermarket slave cylinder is there really a difference other then feeling good about a lighter wallet? Here is the link for the upgraded push rod for the slave DSM Extended Clutch Slave Cylinder Rod - Modern Automotive Performance

I stated that I already had a Extended rod that did NOTHING about my clutch drag. After reading this thread, and comparing the OEM to Aftermarket, I ask the question of a OEM rebuildkit since it comes with the Piston that pushes more fluid (First pic) and a Longer Cylinder Rod so that I will not be on the last teeth. The OEM Slave has a different spring than that of an aftermarket. if I can get away with that slave and an extended rod fine.After reading Rebuild DIY threads it doesnt seem to hard. The only reason Im thinking of rebuilding the Master and Slave myself is because its a good $130 cheaper if the housings are the same.
-Shane

 

[kilo4]

I would stay away from the OEM rebuild kits from part stores. I forgot which store I purchased the kit from but one kit looks physically identical to the OEM. I failed to take pictures and post my measurements, but the the piston lenght was shorter by thousands of an inch. The spring tension was also less compared to the OEM. My freind works at a tool calibration shop and measured it for me.

 

[bertrenolds]

Although this is starting to steal the OP thread to help GsxEcutioner, I Kilo4 made a good point that you should make sure you are properly bleeding your clutch.

9!'clipseDOHC posted this
Here are some how to's:
How to Bleed a Hydraulic Clutch - Team Rip Engineering
http://www.dsmtuners.com/forums/articles-drivetrain/213503-how-properly-bleed-your-hydraulic-clutch.html
http://www.dsmtuners.com/forums/articles-drivetrain/60319-how-bleed-your-clutch.html
Slave Cylinder for the Clutch[/QUOTE]

 

[97gst_spyder]

This is a great thread.

I also used an OEM rebuild it in my aftermarket master, no issues after 3 years.... Hit or miss I guess.

 

[GsxEcutioner]

I've done the bleeding, done the adjusting, still clutch dragging.
-shane

 

[kilo4]

Shane I might be in your area this Saturday. If you want I can come by and see if there's anything I can do to help. I will look for my old notes, but I do remember the master/slave housing cylinder stroke different by 1 mm. I have a good used OEM master cylinder w/ OEM rebuild kit that you could use to help you troubleshoot.

Just for the record, we have someone in Nor Cal running 10's on one of these parts store rebuild kits.TsI believe its the same guy that rebuilt your tranny.

 

[GsxEcutioner]

Shane I might be in your area this Saturday. If you want I can come by and see if there's anything I can do to help. I will look for my old notes, but I do remember the master/slave housing cylinder stroke different by 1 mm. I have a good used OEM master cylinder w/ OEM rebuild kit that you could use to help you troubleshoot.

Just for the record, we have someone in Nor Cal running 10's on one of these parts store rebuild kits.TsI believe its the same guy that rebuilt your tranny.

yea thatd be great,you have my number and I have yours. LMK when you come down. I was talking to Dave , and he told me me to go OEM.
-Shane

 

[mitsubishikid]

Not meaning to revive an old thread or anything but, the 5h picture that you show of the slave cylinder spring is the wrong spring.
I know because I ordered a rebuild kit from auto zone, the small one with the red piston, I told them they ordered me the wrong one so I returned it, then I went online and snagged this part number off of the web and ordered it. see link
http://www.autozone.com/autozone/pa...t-Clutch/_/N-6o2o0?itemIdentifier=227019_0_0_
I did some other research and it turns out the small spring is for the non turbo fwd models, so whoever made the aftermarket slave cylinder for auto zone must have used the wrong spring, but don't get angry just order this from them and rebuild your awd 1g slave with it.
I will post up on a new thread if anything goes wrong, I do agree that the Mitsubishi dealer parts are the best, but I just want an even playing field, so I am gonna try the aftermarket kit first, hey its only $20 bucks, and if it won't work ill just get the oem kit and try that.

thanks for posting up the photos and the info.

 

[TrevorS]

Everyone always recommended OEM but no hard data. I'm hoping this would help others having clutch issues. I've had clutch issues since I purchased my car. So finally my car shifts perfectly.

Here's a list of my "Lesson Learned"
*1. Good pedal assembly (1G)
*2. OEM master and slave cylinder
*3. Properly bled clutch (speedbleeder help)
4. Steel braided hose to slave
*5. Properly shimmed pivot ball (close as possible to my clutch cover)
6. Correct flywheel step height
7. Serviceable clutch assembly
8. Serviceable transmission

*indicates critical steps for proper clutch engagement/adjustment

This is what it took to resolve my clutch engagement issues. Like I stated before, this post was meant to provide some ideas to others experiencing the similar issues.

FWIW -- My slave cylinder died 4/2009 and I replaced both master and slave with PBR aftermarket parts. Following flushing the OE hard line, bleeding, and adjusting the rod, the clutch has been as good as new.