Volvo 940 Turbo Diesel - Grinding Gears

Operator error

1st answer is correct. If clutch was gone the car would not go uphill. The driver is simply not skilled at heel and toe on the clutch and brake.

Clutch must be 99.99% used up and the slight difference in weight, gravity force on the pressure plate is making the release not as effective one direction, but better the other! Only possible explaination!!

Oh yeah I forgot the clutch cable stretches more in one direction than the other

Coming to a complete stop may overcome this irregularity...

Bad synchros?

Is reverse synchronized?

Most don't, some do, see link for partial list.

If the vehicle is stationary and the clutch is "disengaged", then for some reason the gears are still spinning. Period.

You may find the thrust bearing on the clutch pressure plate is worn and dry (should be sealed bearing), and different angle plus gravity is causing it to bind when facing downhill.

Your best bet would be to replace clutch plates and bearing. Or use the synchros in a forward gear to stop the gears spinning before selecting reverse.

If the vehicle is stationary and the clutch is "disengaged", then for some reason the gears are still spinning

There is no clutch brake what do you expect...

Have the same problem with my '87 760 Turbo, mechannic tells me that the reverse bushing is worn out. He tell me it easy to fix, I have not done it because money issues.

There ain't nothing wrong with that grey matter. GA.

Thanks Bob.

Nope. . . . ain't drooling yet!

L J

Worn out or contaminated clutch disk. The rivets on the clutch faces tend to hit the flywheel (downhill side) first. Contamination comes from leaking transmission or crankshaft seals.

In addition the input shaft bearings on the transmission may need to be re-shimmed or replaced.

Diesel engines are heavier than gasoline engines. If the rubber engine and transmission mounts have aged, become oil soaked and are softer than originally, the engine and transmission could be moving forward enough to in effect reduce the travel on the clutch release lever. Also, this could be causing a shift forward of your Halogen headlight fluid in a sloshing motion causing your car to lurch forward as you are shifting into reverse. The car should be motionless when engaging reverse gear, if not you are trying to engage gears turning in opposite directions. See owners manual for further instructions.

Welcome to the insanity. Your humor is good to see.

Ive found that most manuals will grind a bit when shifting into reverse on a downhill.

My opinion is , the car will roll forward slightly as your foot leaves the brake and moves to the clutch . This slight forward motion turns the trans. mainshaft in the opposite direction you need to shift into, thus. the slight mismatch of the syncroes, and a little grinding will occure. If you need to shift to reverse on a downhill grade , try using your parking brake to hold the car from rolling , shift into reverse and release the clutch until you notice the car starting to move or until you notice the engine loading down , then release the parking brake and back up. After a few times you will get the hang of it .

I keep my right foot on the brake pedal and clutch with left foot, I then release clutch and move right foot to accelerator.

It does not grind when it is cold.

Thanks for all your help , the car is always stationary when I try to engage reverse.

This problem started just a few months ago and I have the car 10 years.

I have 5 other vehicles without this problem.

If you have a mechanical clutch, it could be that the engine moves because of loose or a broken mounting and that the clutch cable slackens slightly and thus the clutch is not fully disengaged. Or that the moving of the engine slightly offsets the gear mechanism going into your gearbox also producing the grinding of gears. ( This happened to me once)

". . . . it could be that the engine moves because of loose or a broken mounting and that the clutch cable slackens slightly "

Such a condition would be more likely to cause the clutch to "judder" (grab and slip repeatedly). Worn motor mounts do that be he gave no indication of symptom.

L.J.

Engine mountings look good. Hydraulic operated clutch release.

The time has arrived to adjust the shift linkage or replace bushings etc..

Check your gearbox oil level. If the level is too low it may have an influence. Your downhill facing may causes the oil too move forward exposing the gears at the back. Thats if the engine is mounted sideways. I imagine the gears not in oil may spin faster than the others in oil if it is disengaged. I am no mechanical engineer and am guessing here. So due to the low oil level the sinchro may be out when facing downhill. Cold oil is also more sluggish so when facing downward it wont run so fast to the front.

Reverse gears are rarely synchronized so they will grind if the input shaft driven by the clutch is not turning at the same speed as the reverse gear. When you are facing uphill, the movement of the car turns the reverse gear in the same direction as the clutch driven gear, so it slips into gear smoothly. When you face down hill the reverse is true.

There is really no solution to this problem beyond applying the brake strongly when the car is facing uphill and thus minimize the amount of grinding.

And in addition, change the transmission lubricant and follow Volvo's specifications.

Dennis Waller

So far there does not seem to be any reasonable answers to your problem.

Well I am surprised no one else realized this. As you sit in your Volvo on a hill facing down, your weight shifts forward. Because of the extra weight you are exerting on the steering wheel and the pedals, it requires extra pressure to depress the clutch pedal sufficiently to fully release the clutch disc.

While on an upward hill, your weight is now against the seat back. That allows you extra leg power to completely push the clutch down.

Hey! It ain't any worse than any other post. Good luck.

There were 2 suggestions to engage a forward gear first and then engage reverse which works. I hold down clutch pedal, engage 1st gear then without releasing pedal I engage reverse.

I don't know why I did'nt try this earlier, as I remembered I used to do it with another car several years ago.

Right , this is my first post so be nice to me, The most likely reason for the crunch when engaging reverse gear is because the back axle is mounted on pretty soft rubber bushes that allows the axle to rotate slightly when reverse is engaged ,and this slight rotation causes the drive shaft to also rotate quite a bit as the differential has the effect of gearing up the drive shaft , the differential would have approximately 3.7:1 reduction when going forward when being driven by the engine,and the opposite when the diff drives the" propshaft" 3.7:1 gearing up so the mainshaft in the gearbox is rotating a little in the wrong direction for enough time to cause the crunch.