Georgia Fiero Club Forum

All Things Fiero => Tech Tips, Tech Questions => Topic started by: Budgetman72 on July 29, 2018, 10:56:14 pm

Title: Clutch Problems
Post by: Budgetman72 on July 29, 2018, 10:56:14 pm: Hey folks,
I’ve replaced the clutch pedal, master cylinder “banjo string loop up”, slave cylinder which was leaking and bled the lines several times and it still wont release the clutch fully on my 85 GT! The slave cylinder seems to be traveling full extension which i believe should be 1.2 inches but haven’t been able to measure due to heat shield blocking. All replacement parts are from Fiero Store. What am i missing?

Thx
Title: Re: Clutch Problems
Post by: f85gtron on July 30, 2018, 07:05:08 am: Make sure banjo hole is “down”. Same thing happened to me.
Also, bleeding is tricky. Use every trick you read online.
Title: Re: Clutch Problems
Post by: Budgetman72 on July 30, 2018, 08:25:52 am: That may be my problem then i thought banjo string loop was supposed to be up! I’ll flip it over and hope that will fix it.

Thx
Title: Re: Clutch Problems
Post by: TopNotch on July 30, 2018, 10:52:39 am: Try 2-person bleeding.
1. Open bleed valve.
2. Press clutch pedal.
3. Close bleed valve.
4. Release clutch pedal.
Repeat until no bubbles come out.
Title: Re: Clutch Problems
Post by: Fierofool on July 30, 2018, 11:27:00 am: Quote from: Budgetman72 on July 30, 2018, 08:25:52 am
That may be my problem then i thought banjo string loop was supposed to be up! I’ll flip it over and hope that will fix it.

Thx

The banjo rod should be positioned in this manner:
Title: Re: Clutch Problems
Post by: Budgetman72 on July 30, 2018, 11:52:42 am: Thanks for the photo, thats the position I have the banjo in and i’ve done the vacuum bleed, then the 2 person bleed, then the slave cylinder bleed to a point the fluid coming out is as clean as going in. What’s next?
Title: Re: Clutch Problems
Post by: Fierofool on July 30, 2018, 12:57:23 pm: I have had the most luck with bleeding a good system by using the gravity bleed method. Pumping the pedal can break up air bubbles in the system, only to have them coagulate again. This is a one-man operation and can be a blessing if you have trouble when on the road. Learn how to do it.

Jack up the left front wheel just enough to get it off the ground.

Fill the clutch reservoir to the top. Leave the reservoir cap off and the can of fluid open and nearby. DOT 3 fluid only. DOT 4 in an emergency. Never DOT 5, or transmission fluid.

Using a heavy metal tool, whack the side of the slave several times. This should dislodge air stuck at the pushrod end and allow them to flow up to the bleeder valve. This is the purpose of raising the front wheel off the ground as it also tilts the slave cylinder upward.

Open the slave bleeder valve and notice if there are any air bubbles that come out.

Allow the fluid to flow, keeping watch on the fluid level in the slave. On occasion, whack on the side of the slave again. As it nears the bottom, refill it. At the 2nd refill, allow the fluid to drop to the FULL level, then close the bleeder valve.

If the system is good, you should have a good clutch pedal.

Because the slave fluid line passes close to the coolant hose and exhaust, I insulate it with a length of split plastic wire loom, extending from the flexible portion all the way down to where the line is mounted to the frame. The ribbed plastic acts as a heatsink to keep the fluid from boiling.
Title: Re: Clutch Problems
Post by: Raydar on July 30, 2018, 02:42:28 pm: Did you install Rodney Dickman's master cylinder?
If so, you will probably need to extend the pushrod (it's adjustable) in order to get full extension.
I know of at least two installations (one of which was my own) that required this.

Edit - Ooops... I overlooked the Fiero Store comment.
Title: Re: Clutch Problems
Post by: Fierofool on July 30, 2018, 05:19:32 pm: Even with a TFS slave, Rodney's dual seal kit will fit, or pick up one for an 85 or 86 MR2 at your local Toyota dealer.
Title: Re: Clutch Problems
Post by: Budgetman72 on July 30, 2018, 08:58:51 pm: I believe I’ve done it all now! The pedal feels a lot better now, however still no release. I noticed while pressing the clutch with engine running slowly trying to put in first the car starts rolling no grinding the gear like it does in reverse, is this still clutch hydraulic issue or something else? Will the Rodney Dickman slave cylinder really make the difference or is there something going on machanicaly?

Thanks for all the feedback!
Title: Re: Clutch Problems
Post by: Fierofool on July 30, 2018, 10:47:54 pm: If you can put it in gear, start it and while holding the clutch in, it gradually starts to move, then you have a hydraulic seep. It's probably in the master cylinder. Run your finger way up (Edit)along the banjo rod to see if you might have fluid leaking from the back of the MC. It can run down the firewall and be near impossible to see. (End edit) You can get master cylinders at some of the auto parts stores, but it may be worth the cost of a Dickman unit. The double seal piston on the slave is mostly to reduce the possibility of air being pulled back into the slave. Since you have a new slave with a good bore, you could replace the piston yourself. I think I paid under $10 at O'Rielly. You'll have to use the spring that's in the slave. The Toyota spring is too short.

Reverse isn't synchronized and it's not unusual for it to grind on the 4-speed.

Something just occurred to me. I had a release problem and it turned out to be a cracked slave bracket on my first 85GT. On the second 85GT, when I had the problem, it was the big horizontal bolt that bolts it to the engine. It had worked it's way loose. Observe the slave bracket for movement while someone operates the clutch. If it turns out you need a replacement, I have a couple.

Does the pedal sit about an inch above the brake pedal?
Title: Re: Clutch Problems
Post by: Budgetman72 on August 04, 2018, 10:30:02 pm: Well here’s the update, I've replaced the new master cylinder with Rodney Dickman MC and Still haven same problem! I jacked up the rear end and crawled under to get a better look at the slave cylinder action and noticed what looked like some play in the Clutch Arm where it mounts to the Clutch Fork, i tightened the bolt but looks like there is still movement before the Clutch Fork rod begins to turn. So with that looks like i need to change the arm or the fork or both.
Title: Re: Clutch Problems
Post by: Fierofool on August 04, 2018, 10:54:28 pm: The release shaft is splined and has a place where the pinch bolt passes through the side of the shaft. When tightened, there should be no play. It might be that the bolt has been loose for a while and has allowed the splines to wear a little. Some of the release arms were a problem and were later replaced with cast metal arms. I don't remember what years or transmissions, though. I had 2 85's, but don't remember what style arms they had on the 4-speeds before I changed to an Isuzu transmission in them.

MikeMac has an Isuzu trans that he has removed from his car. The release arm on it is good. He may be willing to sell it to you. I can't help you with the car before the meeting, but if you're available in the morning of Tuesday, the 14th, I am available.
Title: Re: Clutch Problems
Post by: TopNotch on August 04, 2018, 11:07:48 pm: I have a good Isuzu transmission clutch arm in my garage. It doesn't have the pinch bolt, though, because that was missing on the "new" transmission I got from ThaDriver.
Title: Re: Clutch Problems
Post by: Budgetman72 on August 11, 2018, 12:50:14 pm: Final update! Found the culprit the factory clutch arm was cracked in several places so we replaced it with cast iron from The Fiero Store. See photo
Title: Re: Clutch Problems
Post by: Raydar on August 11, 2018, 05:20:47 pm: As I was reading back through this thread, I wondered about that release arm.
Why GM ever thought it was a good idea to manufacture it out of stamped steel is still a mystery to me.

I'm happy that you got it sorted.
Title: Re: Clutch Problems
Post by: Fierofool on August 11, 2018, 05:41:47 pm: I couldn't see the photo or even indication that there was a photo link until I signed in. That's what happens with the third party hosting services like we have on our phones. That's why we urge folks to use a windows based system to post pictures because it public and anyone can see them without registering and logging in.

Next, you might want to replace the slave mounting bracket with Rodney's steel bracket. The factory aluminum ones are prone to breaking with age. I experienced that just before I was about to enter the Tail of The Dragon. Glad it didn't wait until I needed to downshift going into a switchback, or when coming to a stop in I-85 traffic. In an emergency, I have 2 good ones on hand that I can get to someone should they break down in this area.
Title: Re: Clutch Problems
Post by: Fierofool on October 12, 2018, 02:18:44 pm: I have just finished working on a Formula that couldn't be put into First or Reverse without turning off the ignition first. Then when the engine was restarted, the car would try to move with the clutch depressed. It would even pull itself up a slight grade. The clutch pedal wasn't bent and the banjo rod was installed properly. The pedal rested above the brake pedal as it should. The point that the pedal started to give resistance against the pressure plate was almost to the bottom of travel.

Upon inspection, I noticed what appeared to be an extremely short slave pushrod. It only protruded from the slave for about 1 to 1.5 inches, so I got a pushrod from my parts cabinet.

I removed the slave and as I separated it from the mount, the pushrod boot extended. When I inspected it, I found that it actually did have the correct pushrod. It was just fully depressed into the slave, so I reinstalled the slave and pushrod.

Next, I moved the car to an incline, placing the car at a 45* so that the left front wheel was positioned well above the level of the right rear wheel. I then topped up the clutch slave with fluid and opened the slave bleeder valve. Air bubbles galore. Two reservoirs of brake fluid run through it and it's still got air bubbles. Tapping on the side of the slave brings out even more air bubbles that were stuck inside the slave bore.

After a couple more reservoirs of fluid passed through, I closed the bleeder, topped off the fluid and had the owner depress the clutch pedal to the floor and hold it. The pushrod extended way out and I opened the bleeder to find there were a few more bubbles. Closed the bleeder, released the clutch pedal and repeated. On the 3rd press, no more bubbles.

Now the car goes into all gears with the engine running and the owner goes home with a smile on his face.
Title: Re: Clutch Problems
Post by: TopNotch on October 12, 2018, 04:19:45 pm: Quote from: Fierofool on October 12, 2018, 02:18:44 pm
Now the car goes into all gears with the engine running and the owner goes home with a smile on his face.

And hopefully, doesn't disappear.
Title: Re: Clutch Problems
Post by: GTRS Fiero on October 12, 2018, 07:11:08 pm: I see a pattern, here...fix their Fiero, and they leave; don't work on it, and they stick around.

Either way, everyone benefits from these tips.
Title: Re: Clutch Problems
Post by: Fierofool on October 12, 2018, 07:35:31 pm: He won't disappear. He will be at the work session a d meeting tomorrow. He's a dues paying mem er.
Title: Re: Clutch Problems
Post by: GTRS Fiero on January 31, 2019, 06:00:26 pm: Just had to point someone to this thread for help. Illustrations always help.