New here - a bit out of my element and I was unable to find my answer over on the GMT400 forums. I've owned my 94' C1500 with an LM7 engine mated up with an NV3500 5-Speed Trans for about 3 years now and I thought I was in need of a new clutch since it was getting really hard to get it into gear; no grinds, just took some force to get them in.

I apologize in advance for beating a dead horse here - I've been searching the forum/web for a few days now and am unable to find what I am looking for.

Issue/Problem - my clutch pedal feels "odd". Very short, very soft at 1st but then gets excessively hard to push the last bit in: it seems like it has a "secondary push" once you hit the 1st "bottom". I'm unsure how else to explain it...when engaging the clutch, it bottoms out easy but won't go into gear unless you give it another "thrust/hard push" and continues to sink another 1/2 inch, at which point, the gears will go in smoothly. However, you go too far (perhaps the last 1/4" to the floor) and it will not go into gear.

Current Setup - 94' C1500, LM7 5.3L and NV3500 w/external salve cylinder.

by https://www.flickr.com/photos/151789831@N04/
Clutch Master/Slave Cylinder - Duralast Clutch Slave Cylinder PFHK064 (this is actually my 3rd one as the pervious 2 have failed: one started leaking at the reservoir while the 2nd one just seemed to quit internally). It's an all in one system, pre bleed and just install and go. Upon further investigation, is does have a bleeder screw and we've actually tried bleeding it but it didn't help.
For Reference: https://www.autozone.com/drivetrain/...064/274730_0_0

Here's the most recent parts list for the clutch job last weekend:

by https://www.flickr.com/photos/151789831@N04/
Upon taking out the old clutch/fly, it showed very little signs of wear and/or usage. The only thing we noticed that may have been a cause for concern was the throwout bearing:

by https://www.flickr.com/photos/151789831@N04/
Regardless of the condition of the old setup, everything new went in but my problem with the weird clutch pedal engagement was still present. Syncromesh was used to fill up the NV3500.

by https://www.flickr.com/photos/151789831@N04/
I'm a bit lost here but I'm essentially seeking advice on how to combat this issue - I'm open to suggestions/advice/upgrades/etc such as a Wilwood custom setup or anything of that nature. As long it properly functions, I'm all ears. Even if I have to utilize one of those aftermarket pedals they sell for hot rods.

I look forward to hearing from some of the gurus and anyone willing to help me out here.

(Edit: Unsure why pics are double posted and/or linked to album - doesn't show multiple post when i try and edit...)

 

Huh, and no one over at 400 had any ideas?

(welcome by the way, another PNW guy here)

 

Forums aren't what they use to be unlike 10 years ago, when I started using them - it's not entirely dead over there but just didn't get many responses.

 

Yup. I'm a member there too, but not much going on. I was surprised there aren't many (good) swap threads, then I realized its all mainly younger kids and they're all on Facebook. PerformanceTrucks.net is a ghost town too, I'll go hit "new posts" and there'll be like 8 posts with new stuff after a day.

 

You nailed it with the FB comment - everyone is over there but riddled with mostly nonsense.

I've reached out to Wilwood; hopefully they can piece something together for me.

 

Nice. Upgrade for sure with the Wilwood setup. And yeah, I bet fb could be helpful, but the crazies over there and the nonstop bullshit, no thanks.

 

I'd call McLeod and Tick Performance and see if either of their clutch master cylinders would work on your application. It could also be a slave issue.

 

Thanks for the lead - I'll check them out! I hope it's just the slave and not have to drop the trans again but we will if we have to.

 

Been prowlin' the interWebz in search for some answers. As suggested, I got in touch with Tick Performance - someone over there recommended the following:

https://www.tickperformance.com/adju...ct-description

Upon watching the installation video, it looks like it'll take a fair amount of work to get it to work on the GMT400s since the F-Body master is installed at a slant and not straight like our OE setup. I did like the features/build quality of it tho - I wish we had a direct setup for our application.

I did come across some universal setups that I may give a try, depending on being able to source the correct braided SS line that would mate up to an off the shelf slave cylinder:

https://www.tickperformance.com/tilt...r-compact-3-4/

https://www.tickperformance.com/tilt...inder-3-4-dia/

I did also find this Slave Cylinder that is made out of aluminum vs most of the plastic ones on the market - I'm just unsure what kind of insert it has to accommodate for the clutch line:

https://www.rockauto.com/en/moreinfo...=2044&jsn=5462

Perfection also has a braided clutchline already made but it out of stock :/

https://showmetheparts.com/Perfection2/

Wilwood recommended their 3/4 master but hasn't clarified if i can purchase a line and threaded adjustable rod to connect to the factor pedal:

https://www.wilwood.com/MasterCylind...emno=260-15098

I also checked out Wilwoods clutch pedal combos but it looks like getting the OEM pedal off is a bit of a pain lol

https://www.wilwood.com/Pedals/Pedal...%20%20&appid=0


That's about where I am at - waiting to hear back from Tick about using one of the universal ones they have listed, along with their speed bleeder clutch line and see what it takes to get it hooked up to a factory slave.

Wish me luck!

 

I have a 1992 5 speed LM7. I just used a stock replacement clutch master cylinder. Mine has been great since 2013 when i replaced the original one that had my clutch half engaged when it went bad. The old one was all shot inside. Never could tell until i replaced it. It was full of rust.

I used a nitrous line for mine and swapped the master and slave to an fittings for the nitrous line. I think someone on the S10 forum had a thread on this.

 

Over on GMT400, I spotted a thread about another member having issues with his clutch - he posted a link to a YT video from Perfection Clutch and after watching it, I'm inclined to believe that I perhaps missed a few things. Mainly, I'm hoping I simply installed the throwout bearing incorrectly along with a worn fork/pivot ball and/or the bearing retainer on the trans itself. Time to order some replacement parts and go from there - if that doesn't do it, I'll try going the route I mentioned above to eliminate all factors.

Thanks for chiming in y'all.

 

You went from a short style throwout bearing to a medium length and mention it, but don't say if you kept it?
Fork travel should have the 2 tine surfaces -X degrees at rest, and +X degrees at release. This is for fork to bearing interaction, and for fork to ballstud interaction, mainly. The whole fork can have a bend, but we're looking at the fork where it sets in the TOB groove. A taller or shorter TOB can cause what you describe, with the fork hanging up on the groove, or on the ballstud. And a taller one won't "just release it more." It will cause problems.
Sometimes, you gotta start with "stock," figure out what changed, and go from there. I refer to stock locations when modifying a lot of things.
It worked before for 3 years. When you serviced it, what changed?

 

We went with the taller style TOB vs the shorter one that was originally in there - according to the LM7/NV3500 combos out there, the taller TOB is an absolute necessity to make up for the crank depth deference. I had a bunch of different speculations to believe this based on the fact that I'm on my 3rd Master/Slave cylinder which is a result for over extending the clutch pedal due to the shorter TOB? In addition, the old fly/clutch were in excellent condition, with minimal wear - I figured, another tall tale contributed by the shorter TOB? Again, just speculations on my end; I'm far from a certified tech.

Frankly, the TOB is the only thing that changed/different aside from a fresh master/slave, fly/clutch and pilot bearing.

I recently ordered a new fork, pivot ball and bearing retainer - we'll give it another look and see if perhaps we installed the TOB incorrectly or something else that may catch the eye.

 

For whatever it is worth - it was the fork. Some hardware was actually missing entirely. There are still some concerns with the clutch master cylinder as it is SUPER soft but it is operating. I'll continue to explore clutch line options and such to improve engagement in the future. That is all.