Reverse grinding, please confirm the cause Options

[malcolm2]

IIRC when reverse grinds, it is probably caused by the clutch cable, right?

Stretching a bit or the nuts loosened up? And of course the dreaded tube.... but lets not go there yet.

Have I remembered correctly?

[ejm]

Grinding in reverse happens because either the car is still rolling or the mainshaft is still turning. Mainshaft turning could be due to several things including bad clutch adjustment for one mentioned reasons, a warped clutch disc, pilot bearing seizing or not waiting for thin gear oil to slow the mainshaft before trying to engage reverse.

[Peashooter]

Grinding in reverse happens because either the car is still rolling or the mainshaft is still turning. Mainshaft turning could be due to several things including bad clutch adjustment for one mentioned reasons, a warped clutch disc, pilot bearing seizing or not waiting for thin gear oil to slow the mainshaft before trying to engage reverse.

All true. Check you're adjustment first, then check that the clutch pedal travel limiter hasn't slipped down limiting the travel. My car needed the clutch release arm shimmed out due to the arm hitting the case. You have to pull the gearbox but it is an easy fix. Hope it isn't the clutch tube but I think that is not the norm.

[BillC]

If you press the clutch pedal and then quickly shift to reverse, you will normally get a grinding sound. As ejm said, the parts are still rotating at that point, and there's no synchronizer on reverse to slow them down.

A "trick" you can try is to shift to a forward gear first, to stop the rotation, and then shift into reverse. Or, you can press the clutch down and wait 5-10 seconds to shift into reverse (friction will slow the shafts, if you give them time).

If, however, you try the shift-into-forward-then-into-reverse trick or try waiting a bit before shifting into reverse and still get the grind, then your clutch may be dragging a little. A dragging clutch will keep the parts from slowing down.

The two most common causes of a dragging clutch on a 914 are loose/stretched clutch cable or a loose/broken clutch cable tube. A warped clutch disk is another cause, but not as likely as the previous two possibilities.

[mgphoto]

Could be the clutch cable but possible the first/ reverse syncro.
Do the clutch adjustment, check the clutch cable tube for movement and see if the engagement fork is hitting the transmission body.
If the clutch is adjusted correctly than it must be the syncro.
Mike

[malcolm2]

All true. Check you're adjustment first, then check that the clutch pedal travel limiter hasn't slipped down limiting the travel. My car needed the clutch release arm shimmed out due to the arm hitting the case. You have to pull the gearbox but it is an easy fix. Hope it isn't the clutch tube but I think that is not the norm.

Thanks guys. That gives me a few more things to check this week.

Clutch tube is easy to check, I have checked it many times. The PO jack-legged a repair with a U-bolt and a 1/4" thick small plate welded to the outer firewall where the tube exits.... plus he cut several holes in the top of the tunnel for my benefit. (IMG:style_emoticons/default/blink.gif)

I have been seeing a bit more oil on my cardboard under the car. I might be seeing Tranny oil. So maybe the seal is a problem. Tranny oil level check is high on the list.

This grinding has really just popped up. It started about 2 weeks ago, maybe once a day. Then yesterday, it seemed to sound off on about every other shift to reverse.

Not really a grind, but a click-click-click... (IMG:style_emoticons/default/headbang.gif) the comment about the gearset not slowing down makes sense with the sound. The clicks are close together at first, then slow as the gear is found.

It has not been too long that Dr Evil has been thru this box, maybe 20K miles. So I doubt it would synchos.

[malcolm2]

MUCH BETTER

Without raising the rear end, I removed the top fill bolt for the tranz. nothing came out, so I added, probably a 1/2 pint maybe a bit more. Of course until it started running out.

Then I checked the clutch cable holding nuts. I found my old picture and there were about 4 threads showing both in the picture and on the car. So I don't think the nuts worked loose. I tightened the nuts for 1 more thread to show. Still had some play at the top of the pedal.

While on the test drive, I operated the clutch while my hand was in the tunnel, on the tube. No movement.

Clutch friction point seemed a bit higher. I let the oil temp get to 200 and tried a few R shifts.... NO GRINDING.

I guess next time I think the friction point is low, and I start hearing some R issues, I will replace the cable.

Thanks for chiming in. I think we got it. (IMG:style_emoticons/default/beerchug.gif) (IMG:style_emoticons/default/beerchug.gif) (IMG:style_emoticons/default/beerchug.gif)

Clark