Jump to content

IGNORED

grinding into reverse


Recommended Posts

So ive had my car on the road for three years and for three years ive had to deal with it grinding into reverse. The throw on the pedal has been played the master and slave cylinder replaced and the clutch and pressure plate taken out and looked at. if anyone out there has any advice no matter how strange it may sound please pass it along i'm quite desperate to save reverse. thanks, sam

Link to post
Share on other sites

So ive had my car on the road for three years and for three years ive had to deal with it grinding into reverse. The throw on the pedal has been played the master and slave cylinder replaced and the clutch and pressure plate taken out and looked at. if anyone out there has any advice no matter how strange it may sound please pass it along i'm quite desperate to save reverse. thanks, sam

Usually one would start with the basics. Be a little more specific about what you've done with regard to the pedal free play. Make sure the clutch master and slave have the correct bore sizes . Make sure the system is properly bled. When the clutch was out how exactly was it "looked at" to determine that it was ok to re-install? Was the pilot bearing checked?

Steve

Link to post
Share on other sites

we tried to adjust the amount of throw on the pedal by moving the hole fro the pin that connects to the master cylinder because it didn't feel like it was completely engaging but it really did nothing except make it even more difficult to put into the other four gears. the system has been bled several times and i'm quite sure that the master and slave cylinders are no longer the problem. My father looked at the clutch to check if it was warped and had it looked at by a local technician, He also tried to gauge as best he could to see if the pressure plate was ok and from what he could tell (he is quite mechanically inclined) it all seemed to be fine.

Link to post
Share on other sites

How many miles are on this transmission?

If your clutch works fine in all forward gears - it is most likely not your clutch.

Reverse is not synchronized - - when the transmission are well within factory spec - this is not a problem, because you have to come to a full stop, before engaging reverse.

As these transmissions acquire 100,000+ miles the bearings/shafts and synchronizers wear - and it takes reverse gear a bit longer to stop spinning.... this is not all that uncommon.

Could be your transmission is simply in need of a rebuilt.....

FWIW,

Carl B.

Link to post
Share on other sites

My 4 speed transmission did that every time that I put the car in reverse. I ended up replacing it (for other reasons) with a 5 speed, and the new one does not grind going into reverse. I didn't even touch the clutch when I changed the transmission, so my experience agrees with Carl's advice.

Link to post
Share on other sites

A slight clutch drag will cause grinding going into reverse but the synchronizers will overcome the drag and forward gears won't be a problem. That's what synchos do. Slow down or speed up the input shaft so gears can be shifted without grinding. Something has to cause the input shaft to be turning in order for reverse to grind. A worn out transmission can't do that. Transmissions don't turn themselves. A dragging pilot bearing will do it or a dragging clutch. If he's whipping it into reverse too quickly before the input shaft can stop then that's driver error not the fault of the transmission.

Walter, I assume you cleaned the input shaft when you installed the transmission. You may have been dragging the pilot bearing or the disc couldn't move on the splines and stayed in contact slightly with the flywheel when the pressure plate released with the old trans. Cleaned up, those things would be less likely to happen.

Sam, try these things:

Try shifting into a forward gear before quickly shifting into reverse.

As Carl said be at a full stop.

Wait a moment with the clutch pedal depressed before whipping it into reverse.

If it still grinds your clutch is dragging.

Link to post
Share on other sites

I have a very similar problem with mine. I know its not correcting the problem but it stops mine from grinding. Step on clutch, shift into first then go into reverse. don't move the car though, just work the shifter through 1st gear first before going into reverse. it stopped my grinding completely. like i said it doesn't correct the problem but it stops that awful grinding.

Link to post
Share on other sites
I have a very similar problem with mine. I know its not correcting the problem but it stops mine from grinding. Step on clutch, shift into first then go into reverse. don't move the car though, just work the shifter through 1st gear first before going into reverse. it stopped my grinding completely. like i said it doesn't correct the problem but it stops that awful grinding.

This is what everyone should be doing with just about every manual tranny.

Your tranny does not have a reverse synchro. Therefore you should shift the lever into first before engaging reverse. This matches the speed of the transmission to the speed the engine is spinning.

You should really throw it into first and not a different gear though because reverse and first are the most closely matched ratios. You don't have to move the car forward in gear, but you can. Just going through the motion will shift the fork and allow the first gear synchro to do it's job. You shouldn't need to 'quickly' shift into reverse either. Normal speed will do.

If you're regularly grinding reverse because you don't let the transmission match speed, you're destroying your tranny.

Edited by JonnyRock
Link to post
Share on other sites
I have a very similar problem with mine. I know its not correcting the problem but it stops mine from grinding. Step on clutch, shift into first then go into reverse. don't move the car though, just work the shifter through 1st gear first before going into reverse. it stopped my grinding completely. like i said it doesn't correct the problem but it stops that awful grinding.

Shifting into a forward gear before quickly shifting into reverse is a common trick to stop grinding. It was used much more back in the day when we had transmissions that weren't synchronized in first gear in addition to reverse. You'd push in the clutch, hit second, then into first. I still often do it out of habit.

Steve

Link to post
Share on other sites

Most all manuals do not have a reverse synchro. Therefore you should shift the lever into first before engaging reverse. This matches the speed of the transmission to the speed the engine is spinning.

Not even close. In gear, at a standstill, the transmission isn't moving at all. Nothing is turning. The engine is turning but the input shaft is not. That's why the clutch must be pushed in in order to idle at a stop. At a standstill shifting into any gear stops all movement in the transmission.

You should really throw it into first and not "any forward gear" though because reverse and first are the most closely matched ratios. You don't have to move the car forward in gear, but you can. Just going through the motion will shift the fork and allow the first gear synchro to do it's job. You shouldn't need to 'quickly' shift into reverse either. Normal speed will do.

Any gear is fine. It just has to stop the gears from turning. There's no reason first is "better" than any other. They all stop the gears from turning so there's no "matching" going on.

If the clutch is dragging and you slowly shift from a forward gear to reverse the input shaft may begin to spin again and grinding will result. If the clutch isn't dragging then feel free to take your time.

Steve

Link to post
Share on other sites

i wasnt taking credit for it, LOL, just suggesting it to samzhot240 since no one had. I'm new to z's and not a mechanic by any means so I figured I would throw in my two cents to see if i could help him out.

Link to post
Share on other sites
i wasnt taking credit for it, LOL, just suggesting it to samzhot240 since no one had. I'm new to z's and not a mechanic by any means so I figured I would throw in my two cents to see if i could help him out.

It's good, your description was more complete and spot on.

Steve

Link to post
Share on other sites

wow thanks for all the tips this should keep me busy for awhile in a good way. the car has always done it ever since i bought it and i can't say for sure how many miles except that i assume it is 180,000 and hopefully not 280,000. i have gotten it in reverse using the first to reverse method i just honestly didn't know if it could be bad for anything so i tried to limit it. I am pretty new at this stuff as well so all the advice is very welcome also if anyone out there knows of anyone that sort of specializes in Z's in like the Central NY area please leave me a note, i don't really trust taking it to the locals.

Samantha

Link to post
Share on other sites

Hi Samantha, FWIW, when I first got my '73 it, too, ground going into reverse. The original owner said he couldn't figure it out. What I did was to make sure the clutch pedal distance from the floor was up to spec (there is no adjustment on the slave cylinder on later models). It was not and after I adjusted it to spec (in the service manual) using the adjuster that attaches to the pedal up by the firewall the problem went away never to return. Good luck, it requires some serious contortion of the body to do.

Cheers, Mike

Link to post
Share on other sites

Ok so there is adjustment on the pedal itself? because neither my father or i could find any kind any we actually tried changing the hole that the master cylinder piston attaches to but it didn't help at all. My dad really felt being able to adjust the throw on the pedal would make a difference but we couldn't figure out how.

Link to post
Share on other sites

It's fixed finally! With a little custom work on my dad's part we made a small extension for the rod to where it connects to the pedal in order to give the piston on the slave cylinder more throw and finally got dome results.

Link to post
Share on other sites
It's fixed finally! With a little custom work on my dad's part we made a small extension for the rod to where it connects to the pedal in order to give the piston on the slave cylinder more throw and finally got dome results.

Sounds good. Just make sure you still have some pedal free play. If the throwout bearing is in constant contact with the pressure plate it will prematurely wear the bearing out.

Steve

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.