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Clutch Disengagement issues - t5 swap

Old 01-03-2019, 12:38 PM
  #1  
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Clutch Disengagement issues - t5 swap

Hi Everyone,

I have searched the forums for answers but nothing I could find was specific to my situation I've checked everything i've found in the forum and it all looks good...

I've recently converted a 1987 IROC-Z 305 TPI/700R4 to a SBC 350 Carb (for now) T-5. I have everything installed and the hydraulic system completely bled with a MittyVac bleeder. I am getting 0.6" of travel at the slave rod which is within the spec outlined by GM but the clutch will not disengage. With the clutch fully depressed I was able to get under the car and use a pry bar to increase the travel of the clutch fork and disengage the clutch, I could spin the slip yoke with my hand while prying and the pedal pressed but the fork needed to move quite a bit, about an inch by eyeball.

When I installed the trans it went in flawlessly, I did not have to pull it in with the bolts or anything like that. I triple check that the clutch fork is aligned properly with the T/O bearing as well. When i cut the hole in the firewall for the master I used the holes in the factory carpet as a guide, along with the stabilizer bars that are attached to the pedals and go down to the master bolts. There was one thing that I should mention that happened during the initial clutch bleed process. While bleeding the first time the clutch got really hard to press, then suddenly a "snap" sound and the pedal felt more normal. Nothing was broken after taking it all apart again, I assumed the sound was linked to the fingers on the pressure plate breaking free, it had sat for a while but wasn't rusted or anything.

**Disclaimer** Parts Used or Re-Used:
New pilot bearing (National)
New T/O (National)
New Master (LuK)
New Slave (LuK)
Nodular Iron 16lb Flywheel, turned. (Clutch not hitting bolts)
Used Clutch Disc (appeared good condition)
Used Pressure Plate (appeared good condition)
Used Clutch fork
Used pivot ball.
Donor car was a 1985 IROC-Z 305 T-5.

Any help would be appreciated, this isn't my first car build but my first experience with a t-5. I'm not sure what else could be causing my issue.

Thanks.
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Old 01-03-2019, 04:35 PM
  #2  
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Join Date: Jun 2002
Location: North East GA
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Car: 1989 Firebird
Engine: 5.7 LS1
Transmission: T56
Re: Clutch Disengagement issues - t5 swap

I ran into similar issues with my t56 swap. The clutch would drag and not fully disengage. I came to the conclusion that I didn't have enough pedal travel with the 4th gen clutch pedal and the 4th gen master. But in your case I'm assuming the clutch pedal and master came out of a 3ed gen.

I've seen post where people have had the clutch disk in backward and also the T/O bearing not shimmed.

In my case I replaced the master with a aftermarket clutch master with a bigger bore and adjustable pedal arm so now I have a lot more pedal travel and absolutely full disengagement... I could also dump the clutch and blow my 10 bolt so I have to keep that in mind LOL.
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Old 01-03-2019, 08:31 PM
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Transmission: `95 T56 \ `88 200-4R
Re: Clutch Disengagement issues - t5 swap

https://www.thirdgen.org/forums/transmissions-drivetrain/353275-how-install-throw-out.html

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Old 01-04-2019, 05:45 PM
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Re: Clutch Disengagement issues - t5 swap

Thanks for the reply. Yeah the pedal assembly is from an 85 Camaro so it "should" be good there. I also bought a new MC for an 87 Camaro Iroc.

Even though i've never done the flipped clutch thing in my life, I did double check that when i had the transmission out.

Last edited by ZCanuk; 01-04-2019 at 05:50 PM.
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Old 01-04-2019, 05:48 PM
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Re: Clutch Disengagement issues - t5 swap

Thanks,

As I noted though, that is the first thing I checked. The clutch fork is installed correctly on the T/O bearing. The ears are inside the lip as intended.
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Old 01-04-2019, 06:11 PM
  #6  
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Car: 1989 Firebird
Engine: 5.7 LS1
Transmission: T56
Re: Clutch Disengagement issues - t5 swap

Only thing I can think of is either bad slave cylinder, wrong slave or master, or the shims on the TO bearing assuming no air in the line which can be real hard to blead out.

i found the technique where you use a vacuum pump to pull a vacuum and let the fluid back flow works the best on the clutch.
​​​​​​
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Old 01-04-2019, 06:16 PM
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Re: Clutch Disengagement issues - t5 swap

This technique (didn't watch entire video just found it as example)

​https://youtu.be/b28CahjQd48​​​​​​
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Old 01-04-2019, 06:39 PM
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Re: Clutch Disengagement issues - t5 swap

Yeah that is similar to what i did but I used an actual brake bleeder;
https://www.harborfreight.com/mityva...ump-39522.html

I actually held 20 inches of vacuum from the reservoir for about 30 minutes and no air came out, rules out leaks too. I'll have to check on the master and slave but they were both new when installed. I'm also not familiar with what you mean by shims on the T/O bearing, I wasn't aware they needed to be shimmed.
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Old 01-04-2019, 06:44 PM
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Re: Clutch Disengagement issues - t5 swap

https://www.speedwaymotors.com/the-toolbox/how-to-install-a-hydraulic-throwout-bearing/28841
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Old 01-04-2019, 07:01 PM
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Re: Clutch Disengagement issues - t5 swap

Oh I see, you're talking about a full hydraulic release bearing. I'm still using the stock t-5 set-up with a clutch fork.
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Old 01-05-2019, 12:53 AM
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Car: 1991 Z28 5spd
Re: Clutch Disengagement issues - t5 swap

I have a 92 Z28 T5. All stock. Decided to replace the clutch master and slave and line at the same time.
I had a hell of a time getting the system bled. After trying the shop manual procedures And other procedures, and just pulling hair out for 2 days, I found a solution that finally worked. And it's really simple and clean.
1. remove the slave from the trans and let it hang from the line.
2. Have a second person watch the resivoir with the cap off and keep the resivoir full.
3. Push the slave piston in fully by hand, ( yes it takes a lot of force). Do this slowly both in and out. Hold the piston in for a few seconds to let the bubbles rise up the line. Don't let the internal spring push the rod out too fast or it could suck some bubbles back in from the line. This was the mistake I made the first time.
4. Keep the line side of the slave tilted slightly up, so air can go upward.
5. Do this until your helper sees no more air come out of the master resivoir. Took me about 10 to 15 pumps.
6. This worked great for me. Even after I had to replace the failed Rock Auto slave a few weeks later.

Hope this helps.
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Old 01-05-2019, 01:01 AM
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Re: Clutch Disengagement issues - t5 swap

I should have mentioned, It doesn't take much air at all in the system to keep the clutch from disengaging. We say just a few little bubbles come out. But it made all the difference. That's why I suggest trying this procedure first before spending any more time or money if you're pretty sure everything else is right.
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Old 01-05-2019, 12:12 PM
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Re: Clutch Disengagement issues - t5 swap

Originally Posted by jczoka View Post
I should have mentioned, It doesn't take much air at all in the system to keep the clutch from disengaging. We say just a few little bubbles come out. But it made all the difference. That's why I suggest trying this procedure first before spending any more time or money if you're pretty sure everything else is right.
Thanks,

I'll this a try before I buy any parts. I've had some private messages saying to replace the clutch fork and pivot ball as well. I'll try bleeding with this method and if that doesn't work i'll get my hands on a new fork and pivot. They don't cost much so it's worth a try.

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Old 01-05-2019, 06:53 PM
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Car: 1991 Z28 5spd
Re: Clutch Disengagement issues - t5 swap

Let us all know what you find. A Clutch is my next big job. If you find something odd it could help us T5 guys in the future.
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Old 01-05-2019, 10:14 PM
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Re: Clutch Disengagement issues - t5 swap

Originally Posted by jczoka View Post
Let us all know what you find. A Clutch is my next big job. If you find something odd it could help us T5 guys in the future.
Well I tried bleeding the clutch gain and no bubbles were coming up through the reservoir so i removed the trans again. Upon further inspection it looks the the flywheel i have has been turned before and isn't allowing enough clearance to the bolts, even though i have the ARP small head bolts. I didn't realize it before because when i installed the clutch everything looked good but the disc spring move around a bit and it was binding. I ordered a new 15lbs flywheel and a clutch kit to be safe. I'll let everyone know the results.

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Old 01-06-2019, 03:23 PM
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Car: 89 IROC
Engine: 6.8 HSR N2O
Transmission: TKO 600
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Re: Clutch Disengagement issues - t5 swap

I had the same problem with my install. I pulled my master cylinder and made it adjustable. This allowed me to get a little extra stroke. I also may have mounted my master a little low on the firewall which loses some stroke. Make sure your braces from the pedal bracket to the master are in place and tight. The adjustable rod has come in handy many times. Check that your pivot points are tight too. I made a bronze bushing for my pedal to master joint cause the plastic one would wear out quickly.
I've gone through 7 different clutch sets and noticed that different clutch/pressure plates need more stroke and the high clamp PP may tend to flex the parts (fork, linkage etc) I have used stock, Zoom, Ram and Centerforce clutch sets. Most didn't hold up for my combo and the Ram was so stout that my hydraulics eventually blew out. I ended up with a McLeod dual disc RXT and it holds the power. The only problem is it is super expensive and tends to warp the floater plate if slipped too much.
I have also seen some adjustable pivot ***** for the T5. This could help if the fork position isn't ideal but it won't give you extra "stroke".
One other tip, the clutch pedal has to return high enough for the master to return to it's top position. I speculate that when it's held down just a bit it can't let more fluid into it from the reservoir. Even if the pedal has some slack it may still be holding some pressure on the fluid. I believe it has to return to the top to give all of available stroke and/or allow air to escape to the reservoir. You can bend/tweek the upper stop and the lower stop. This allows you to maximize the pedal travel too.

Last edited by antman89iroc; 01-06-2019 at 03:34 PM.
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Old 01-13-2019, 11:16 AM
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Re: Clutch Disengagement issues - t5 swap

Doubt this is it, but figured I'd throw it out there.
When istalling my TKO, I used a Lakewood bell, which required an adjustable pivot ball. Took me little while to figure out why the clutch wouldn't fully disengage. ...doesn't sound like that's your issue, but keep the geometry of the linkage in mind too. You're using a used fork, pivot, and presumably stock bell. And chance something is maybe bent? -or somehow changing the geometry? Likely not the case, but something to look into.
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Old 01-13-2019, 04:09 PM
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Engine: A brand new 350 with a forged lower
Transmission: 5 speed, TKO600.
Axle/Gears: 10 bolt 373 modified
Re: Clutch Disengagement issues - t5 swap

The master cylinder is extreemly hard to bleed on these cars because the way it is mounted. The rear sits above the fluid port from the reservior. What l did was used a hand vacuum pump on the reservior and then pushed and released the clutch pedal several times. Check to make sure the vacuum is there & keep the reservior full.
Once the master has no more air in it, gravity will bleed the slave. Once the master is bled, you will know by how it " feels".
Somebody mentioned an adjustable pivot in the bell housing. That is real possablity, but only usually used on a blowshield .
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Old 01-13-2019, 04:11 PM
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Car: Got me a nice little '86 Z28.
Engine: A brand new 350 with a forged lower
Transmission: 5 speed, TKO600.
Axle/Gears: 10 bolt 373 modified
Re: Clutch Disengagement issues - t5 swap

By the way, l went through 4 . T5's before l went TKO600. Too light of a trans.
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