Car grinds going into reverse

[Dave R.]

I have a 1969 4 speed that grinds horribly whenever I try to put the transmission in reverse; so bad that I have to turn the car off, put the tranny in reverse and then start the car up again in order to back up.
I have been told by members on another forum that this may be caused by a throw out bearing being installed incorrectly.

I would appreciate any opinions that members here may have and any solutions that they may have to offer. I am considering selling the car and would like to get this repaired before putting the car up for sale.

Thanks

[Joe C.]

Re: Car grinds going into reverse

Rear synchro.



Check clutch freeplay.
Put it into a forward gear, then reverse, before letting out the clutch.

If you overhaul transmission, be sure to replace the reverse idler gear, which is probably "toast".

Joe

[Dave R.]

Re: Car grinds going into reverse

So you are leaning more towards a transmission rebuild and not a throw out bearing issue.

[Jim L.]

Re: Car grinds going into reverse

I have a 1969 4 speed that grinds horribly whenever I try to put the transmission in reverse;

This could be caused by many different things. The fundamental problem is that the transmission input shaft continues to turn even though you've depressed the clutch pedal.

Here are some possibilities:

1. The clutch is misadjusted. One clue to this would be that you have a lot of free play at the top of the clutch pedal's travel. Opinions vary on how much is the proper amount.... I shoot for something around 3/4" to 1".

2. The bellhousing isn't properly indexed to the block. Indexing means several things: That the transmission mounting hole is concentric with the engine crankshaft, that the transmission mounting surface is parallel with the crank flange, and that the flywheel doesn't have excessive surface runout. Checking for any of these involves removing the transmission and using a dial indicator (and perhaps some shims) to measure and correct any problems.

3. Someone installed a roller bearing style pilot bearing, and did so in such a way that the bearing is damaged, and seizing on the tip of the transmission input shaft.


Whatever the cause, it's affecting more than just your ability to get the transmission into reverse. It's also causing more rapid wear on the synchros for the forward gears. This needs to be fixed whether you sell or keep the car.

Good luck.

Jim

[Dave R.]

Re: Car grinds going into reverse

Does anyone know of a shop they can recommend to address my transmission problem in the So. Jersey (Atlantic City) area?

[Edward S.]

Re: Car grinds going into reverse

One place you can try is I think the name of his shop is Restoration Conne ction in Egg Harbor ask for Rob English. I have home phone number but can't get to it until Tuesday. Good luck.

[Duke W.]

Re: Car grinds going into reverse

Why not start with the most common and easiest condition to correct - clutch drag due to excess freeplay.

So how much freeplay does the pedal have?

Take an analytical approach:

How long has this condition been present?

Did it happen suddenly or gradually?

Is there any problem engaging the forward gears?

Was any work done on the car about the time it started?

Reverse is a non-sychronized sliding gear. If you declutch and immediately engage reverse, there will usually be a gear clash. This does not happen in the forward gears because of the synchronizers. If you wait a couple of seconds for the countershaft to spin down after depressing the clutch, there is usually no clash unless the clutch is dragging, which prevents the countershaft from spinning down.

Another method is known as "clearing the gears". Depress the clutch, engage a forward gear, then reverse. The forward gear sychronizer action stops the countershaft allowing the reverse sliding gear to be engaged without clash. (I was taught this procedure on a '49 Chevy with the three speed non-synchro first gear column shifter at about age 12.)

Occasionally the reverse sliding gear will not engage because the tooth crowns are aligned. In this case - just reclear the gears.

[Dave R.]

Re: Car grinds going into reverse

I have owned the car for approximately 2 years now and the problem has gotten increasingly worse with time. Engaging the forward gears is not a problem although I occassionally feel a slight scratch going from 1st to 2nd gear (not always and it's not something you can hear, I really just feel it though the shifter).

I have tried clearing the gears by shifting into a forward gear before trying to shift into reverse and it makes no difference.

There was no work done to the car prior to this condition starting although the previous owner did say he installed a new clutch before I bought the car.

I think I need to locate someone I can trust to diagnose, and repair, the car before I consider selling it.

[Stuart F.]

Re: Car grinds going into reverse

Using Duke's analitical approach: Clutch, Clutch, Clutch!

Duke; Those "H" box shifters on the old Chevies were a piece of art. I had that set up on a 50 Chevy w/my 58 Fuelie engine and a truck 3 speed for a while. I made a relay lever mounted off the normal clutch mount on the side of the engine and cobbled up some shifting rods. But the neat thing about the "H" box was it's adjustability. You could set up the interchange between the 1st/rev and 2nd/3rd so you could really slam a fast 1st to 2nd shift. I went through 3 truck boxes, busting out the countershafts on 2 of them until I got smart and went to an open drive shaft.

Again: Clutch, Clutch, Clutch.

Stu Fox

[Bill M.]

Re: Car grinds going into reverse

I haven't personally had this problem, but I would guess that your clutch disc is stuck on the input shaft due to corrosion and is not free to properly release from the flywheel.

[Stuart F.]

Re: Car grinds going into reverse

Dave;

I think Bill has it right. I spoke with a fellow at last nights cruise with a 64 Fuelie and his is so bad he can't get the clutch to release at all any more. It too just came on gradual over time and he was having to let the car sit for upwards of a month some times.

Stu fox

[Dave R.]

Re: Car grinds going into reverse

If the clutch disc is stuck on the input shaft how do I correct this? Why wouldn't this affect shifting into the forward gears?

[Bill M.]

Re: Car grinds going into reverse

If the clutch disc is stuck on the input shaft how do I correct this? Why wouldn't this affect shifting into the forward gears?

You'll have to pull the trans and clean up the splines on the input shaft and the disc.

Synchros act on the input shaft to match its speed to that of the output shaft.

[Stuart F.]

Re: Car grinds going into reverse

Dave;

Right now it is just hanging up - binding/sticking - and not frozen in place. Mine has had this "early" binding/sticking condition for a number of years now. The longer the car sits, the more acute it is. I usually "pop" the clutch pedal a few times when I first start it after a lengthy layover. Even then it may give me some grind into reverse, specially the second time I go into reverse in the drive way. As a matter of routine I start in reverse to try and avoid this. After driving for a while, it works fine. How about yours? Does it get better after/during a drive or stay the same? Also, even if your clutch linkage play is adjusted properly, if you have more than one floor mat like me, you may be affecting it's action. I have carpeting, plus a carpeted floor mat, and a rubber mat on top of that. So, I usually have to stand on it pretty good.

Stu fox

[Dave R.]

Re: Car grinds going into reverse

Stu,

I always start the car in reverse simply because the car needs to be in reverse in order for me to get the key out so when I get back into the car the next time I want to go for a drive it's already in reverse.
Unfortunately the condition does not improve after a lengthy drive or after driving the car more frequently. I don't drive the car a ton but, I try not to let it sit longer than a week before I take her out.

I am thinking about calling the Corvette Paramedics in Mt. Holly to take a look at the car since I am not equipped with the tools or knowledge to try and make the repair myself. Does anyone have any experience with these guys and/or can you recommend someone to check this out for me?