4+3 trans problem
Thread Starter
Advanced
Joined: Mar 2004
Posts: 75
Likes: 0
From: West Des Moines IA
4+3 trans problem
Thanks in advance for any input. 4+3 trans in low mile 86 shifts hard into forward gears and will not go into reverse unless quickly shifted from a forward gear due to grinding. I replaced master and slave cylinders although old one didn`t leak and bled to the best of my ability. Problem remains. Any type of information on this subject would be greatly appreciated.
Burning Brakes
Joined: Mar 2013
Posts: 1,131
Likes: 5
From: Illinois/Wisconsin Line
I would think ur first step is to get it up in the air somehow and have someone push the clutch pedal to the floor while someone else gets up under there and measures ur actual disc to flywheel air gap and first with just 1 push to the floor and thenl then after that a pump of the pedal and get a measurement of that also to start to find out whats going on before u get real worried.
Low or hardly any Disengaugement/air gap Hyd's or bent something
Good air gap Clutch time although cant remember, exactly what it was but if it starts grinding in rev { the first sign } it could be something else in the 4 plus 3 that goes bad causing this
Low or hardly any Disengaugement/air gap Hyd's or bent something
Good air gap Clutch time although cant remember, exactly what it was but if it starts grinding in rev { the first sign } it could be something else in the 4 plus 3 that goes bad causing this
Last edited by cudamax; Jul 19, 2014 at 04:34 PM.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
You more than likely still have air in the system. I use a pressure bleeder and get it all out when I do them.
If you fighting to get it into gear...regardless if the engine is running or not...You have a hydraulic problem...or a problem in the clutch...and if it is low miles on it. I would make sure it bleeds out. All it takes is a small bubble to mess it up.
LOOK for ANY sign of fluid leaking.
EDIT: It is possible that the clutch disc is stuck to the flywheel or pressure plate and not releasing. This will cause eh main shaft of the transmission to keep turning...and make it darn near impossible to get it into gear WHEN THE ENGINE IS RUNNING. IF..you can shift it perfectly when the engine is NOT running...and crank ti and it will not shift...I would think that is is in the clutch area. OR...the input shaft is seized to the pilot bushing and it is doing the same thing...the input shaft is turning when the engine is running...which is NOT good.
DUB
If you fighting to get it into gear...regardless if the engine is running or not...You have a hydraulic problem...or a problem in the clutch...and if it is low miles on it. I would make sure it bleeds out. All it takes is a small bubble to mess it up.
LOOK for ANY sign of fluid leaking.
EDIT: It is possible that the clutch disc is stuck to the flywheel or pressure plate and not releasing. This will cause eh main shaft of the transmission to keep turning...and make it darn near impossible to get it into gear WHEN THE ENGINE IS RUNNING. IF..you can shift it perfectly when the engine is NOT running...and crank ti and it will not shift...I would think that is is in the clutch area. OR...the input shaft is seized to the pilot bushing and it is doing the same thing...the input shaft is turning when the engine is running...which is NOT good.
DUB
Last edited by DUB; Jul 19, 2014 at 06:30 PM.
Instructor
Joined: Oct 2007
Posts: 188
Likes: 3
the line
Hi, no expert here, but I had a lot of issues bleeding the master and slave. I solved my issues with 2 changes:
- It took me a lot of time to realize the rubber and steal pipe from the master and slave was bad. I replaced this with a hose you can make at any hydraulic line shop - it made a lot of difference. Slicing the old hose in half showed that the outside looked good, but the hole was reduced and not clean. The hose deteriorated. Cheap
- Two threaded shafts and a fence gate turn buckle with 2 nuts can make you an adjustable slave to fork push rod. This allowed me to change the shaft length to be slightly tight - no slope and worked much better.
http://forums.corvetteforum.com/c4-t...od-length.html
I am not a transmission guy, others know a lot more than I do, but these 2 things help me.
- It took me a lot of time to realize the rubber and steal pipe from the master and slave was bad. I replaced this with a hose you can make at any hydraulic line shop - it made a lot of difference. Slicing the old hose in half showed that the outside looked good, but the hole was reduced and not clean. The hose deteriorated. Cheap
- Two threaded shafts and a fence gate turn buckle with 2 nuts can make you an adjustable slave to fork push rod. This allowed me to change the shaft length to be slightly tight - no slope and worked much better.
http://forums.corvetteforum.com/c4-t...od-length.html
I am not a transmission guy, others know a lot more than I do, but these 2 things help me.
Last edited by Frank-in-San-Diego; Jul 19, 2014 at 07:45 PM.
Racer
Joined: Dec 2003
Posts: 277
Likes: 3
Thanks in advance for any input. 4+3 trans in low mile 86 shifts hard into forward gears and will not go into reverse unless quickly shifted from a forward gear due to grinding. I replaced master and slave cylinders although old one didn`t leak and bled to the best of my ability. Problem remains. Any type of information on this subject would be greatly appreciated.
Melting Slicks
Joined: Jan 2008
Posts: 2,054
Likes: 120
From: AZ
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Racer
Joined: Mar 2014
Posts: 330
Likes: 48
From: Poconos PA
Hmm, I can't get my 85 with a rebuilt transmission into first gear without putting it into 2nd gear, then pushing up to first. Also can't get it into reverse without grinding unless I put it in another gear first, then move it to reverse.
I really do hate this transmission, I will be following this thread to see what becomes of it as I need to tackle this problem next.
I really do hate this transmission, I will be following this thread to see what becomes of it as I need to tackle this problem next.
Drifting
Joined: May 2006
Posts: 1,428
Likes: 7
From: Chewelah Wa
If any of you guys had your flywheel ground, you most likely need a new (longer) clutch pushrod. And you may have some wear on your clutch pedal pivots. I made a new rod a quarter inch or so longer out of an 8mm allen wrench. Solved all my problems (going on 7 years now).
Safety Car
Joined: Oct 2007
Posts: 4,426
Likes: 229
From: Pennsylvania
Hmm, I can't get my 85 with a rebuilt transmission into first gear without putting it into 2nd gear, then pushing up to first. Also can't get it into reverse without grinding unless I put it in another gear first, then move it to reverse.
I really do hate this transmission, I will be following this thread to see what becomes of it as I need to tackle this problem next.
I really do hate this transmission, I will be following this thread to see what becomes of it as I need to tackle this problem next.
Last edited by FOURSPEEDVETTE; Jul 22, 2014 at 10:44 PM.
Racer
Joined: Mar 2014
Posts: 330
Likes: 48
From: Poconos PA
Sounds like you have a slave cylinder problem. Not a transmission problem. Turn off the ignition and see if it goes right into gear with no problems. If so, look at your slave cylinder for leaks or it may just need bled. Like bleeding your brake line for air. Simple to do.
Safety Car
Joined: Oct 2007
Posts: 4,426
Likes: 229
From: Pennsylvania
Just went and checked, the transmission shifts into gears pretty easily with the car off, and when it's on it doesn't want to shift. It say for like 10 years before I bought it, so I guess it's time to change that fluid and bleed the slave as you mentioned. I've only bled subaru's before so if this is anything like that, then I should be able to fix it with my brother, thank you for the tip!
Burning Brakes
Joined: Mar 2013
Posts: 1,131
Likes: 5
From: Illinois/Wisconsin Line
If any of you guys had your flywheel ground, you most likely need a new (longer) clutch pushrod. And you may have some wear on your clutch pedal pivots. I made a new rod a quarter inch or so longer out of an 8mm allen wrench. Solved all my problems (going on 7 years now).