gearbox noise

[pat180269]

Some time ago I posted on here about whining from the gearbox in all gears except top. The consensus was that main bearing was shot in the gearbox.

I happened upon a NOS gearbox; still in the box with rover labels never fitted to a car. I fitted this, refurbished the linkage, fitted a new clutch, rebuilt the clutch master and fitted a new clutch slave. Also adjusted the clutch arm according to the book.

Guess what ? Its exactly the bloody same as the old box.

1) The box is noisy in 1st ,2nd and 3rd
2) When cruising on the motorway its noisy when coming off the power, goes quiet when power is applied again.
3) After a run and going into idle, the release bearing or input shaft is noisy; it goes quiet when the clutch is depressed.

The drive train feels very agricultural. I have never driven another P6 but find it hard to believe this is normal.

What's wrong ?

Pat

 

[harveyp6]

I stick to my original diagnosis, even though it's another gearbox....

 

[SydneyRoverP6B]

Gee that would be seriously annoying Pat having found and fitted a NOS gearbox, only to have it as noisy as the old one that it replaced.

Was the quality control on the manual boxes far less than it should have been Harvey?

Ron.

 

[harveyp6]

Was the quality control on the manual boxes far less than it should have been Harvey?

There were problems with the gearboxes on early cars, but once they were sorted they were pretty reliable.

 

[harveyp6]

The drive train feels very agricultural. I have never driven another P6 but find it hard to believe this is normal.

What's wrong ?

Pat

It shouldn't be like that. Check engine gearbox and diff mounts, make sure all the tunnel access grommets and plates are in place, check the prop alignment.

 

[pat180269]

Logically there are only three possibilities:-

1) They all do it and I am being too critical comparing it to a modern car but it is very unrefined.
2) The source of the problem has nothing to do with the gearbox; maybe diff, prop shaft or other cause.
3) As Harvey says, the new box has exactly the same problems as the one in my car which had covered 66K.

I find it hard to believe that the new box has the same problems as the old one - whining,bearing noise in neutral and general unrefined drive train. I am driving a 2000TC on friday courtesy of Happy days so at least I have a reference point.

 

[harveyp6]

1) The box is noisy in 1st ,2nd and 3rd

That could be laygear bearings, but as they're always totally immersed in the oil, it's more likely 1st motion shaft bearing.

2) When cruising on the motorway its noisy when coming off the power, goes quiet when power is applied again.

That sounds like gear noise, or gears moving around when the load comes off.

3) After a run and going into idle, the release bearing or input shaft is noisy; it goes quiet when the clutch is depressed.

Release bearing will be noisy with your foot on the clutch, what you have confirms the diagnosis of problem 1.

 

[pat180269]

Hi harvey, thanks for your continued support advice with this.

NOS gearbox came with new snub rubber and I set up rear mount and front engine tie bar so that crossbar was in the centre of the snub rubber hole.

Here is a picture of the box on the bench before it went in.

The date code was late 1973 and the top of the bell housing had orange paint on it. ( don't know why )
It was clear it had never been fitted to a car so either NOS or factory refurbished.

The top of the N/S front engine mounting has broken up, I noticed this when I refitted the bolts after tilting the engine back.
One other thing, when you come off the power when cruising it feels like the car is juddering, and smooths out when you apply power. The engine is strong and smooth.

How do I align the propshaft ? I marked it before I removed it at the rear and aligned on reassembly but the box was changed at the front so didn't bother there.
The UJ's looked very good, new nylocs.

Tell me more about the diff and extension tube - bearing and mounting.

pat

 

[harveyp6]

The date code was late 1973 and the top of the bell housing had orange paint on it. ( don't know why )
It was clear it had never been fitted to a car so either NOS or factory refurbished.

The orange marks have been discussed on here previously, my memory being that when there was all the trouble with the early boxes, ones that had been modified got the orange mark, but I would think that would have been done away with long before 1973.

The top of the N/S front engine mounting has broken up, I noticed this when I refitted the bolts after tilting the engine back.
One other thing, when you come off the power when cruising it feels like the car is juddering, and smooths out when you apply power. The engine is strong and smooth.

The juddering could be the prop bolts hitting the pinion crossmember because the mounting has collapsed, or the spacers are fitted incorrectly.

How do I align the propshaft ? I marked it before I removed it at the rear and aligned on reassembly but the box was changed at the front so didn't bother there.
The UJ's looked very good, new nylocs.

There is an arrow on the short yoke, (normally in line with the grease nipple), and another on the front end of the main prop tube. The arrows need to be in line, and when they are the U/J's will be out of line, and that's how they are supposed to be.

Tell me more about the diff and extension tube - bearing and mounting.

The mounting I mentioned above, the pinion bearings don't give a lot of trouble.

 

[harveyp6]

There is a bit missing from the gearlever mounting in that pic, and so if you fitted it like that the gearlever grommet must be missing, and that will account for a lot of the noise.

 

[pat180269]

The lever was just thrown in to aid lubing the linkage; it was fitted properly and the white spherical bush was replaced.

Here is another picture of the gearbox



And another as it arrived just removed from the crate.

 

[pat180269]

The problem I have with accepting it's the gearbox is that common sense tells me that if you change a part and the problem is exactly the same afterwards then you changed the wrong part! I know the counter argument is that if you change the part with one with the same fault......., but is this really likely?

Its not a gearbox off ebay or fitted off the floor having already been removed from a car and sold as "good". Besides its not the most difficult component to test at the factory.I can contact the vendor and get a replacement, but its an awful lot of work and I have serious doubts the result would be any different than the other two boxes.
I stripped the old box to remove the input shaft to use as a clutch alignment tool, and it was in good condition.

The driving experience is exactly the same as before, all the faults I mentioned were on the old box and clutch. The only difference was that with the old box the speedo needle used to wobble but with this one its steady. Also the gear lever rattle is gone with the linkage work.

The new gearbox had the clutch arm fitted incorrectly I needed to turn it on the splines when I adjusted it. Don't know if this is typical from the factory.

Is it possible to put a side load on the layshaft via the output shaft if something is amiss downstream? For example if the engine and gearbox moved out of line with the propshaft or if there was a problem with the differential or a driveshaft ?

 

[harveyp6]

The problem I have with accepting it's the gearbox is that common sense tells me that if you change a part and the problem is exactly the same afterwards then you changed the wrong part! I know the counter argument is that if you change the part with one with the same fault......., but is this really likely?

I agree it's not likely, but that's not to say that it will never happen.

I stripped the old box to remove the input shaft to use as a clutch alignment tool, and it was in good condition.

What was the bearing like?

The driving experience is exactly the same as before, all the faults I mentioned were on the old box and clutch. The only difference was that with the old box the speedo needle used to wobble but with this one its steady. Also the gear lever rattle is gone with the linkage work.

Speedo waver is often the rear flange loose, and that may have been cause or result of the problems with that (the original) box.

The new gearbox had the clutch arm fitted incorrectly I needed to turn it on the splines when I adjusted it. Don't know if this is typical from the factory.

You can't set the drop arm accurately until the box is fitted.

Is it possible to put a side load on the layshaft via the output shaft if something is amiss downstream? For example if the engine and gearbox moved out of line with the propshaft or if there was a problem with the differential or a driveshaft ?

Because the gears are helical cut then driving normally puts side loads on the laygear (and mainshaft), and the same thing will apply from the back forwards when on the overrun.

 

[pat180269]

The only thing that I noticed on both boxes was that the input shaft could be moved side to side by a few mm's. I was surprised by this but a mate said it was normal in his experience with VW's. When the box is installed that end is supported in the spigot bearing anyway so I was happy with this explanation.

On the old box the bearing was in excellent condition. There was a chipped tooth on one of the synchros but I found that in the drain plug and removed it at the last oil change.

I am intrigued about the juddering when cruising and coming off the power. The garage where I keep the car is on a slight incline and the car is very clunky reversing up into the garage repeatedly slipping the clutch and taking up the drive.

If we assume for a minute that the gearbox is not faulty, what other things should I be checking ? Final drive ?

 

[Demetris]

2) When cruising on the motorway its noisy when coming off the power, goes quiet when power is applied again.

Mine used to do that with old and worn out UJs both on propshafts and halfshafts.

Are you sure that what you hear is indeed gear noise and not something touching somewhere that it shouldn't?

You say that the N/S engine mounting was broken. Well, did you do anything about it? A failed mounting will probably cause judder and allow the driveline to bang onto the base unit at various places.

 

[pat180269]

Are you sure that what you hear is indeed gear noise and not something touching somewhere that it shouldn't?

No I am not sure. It seems inconceivable that the new gearbox has the same fault as the old one. The juddering coming off the power is becoming more relevant in my mind. Your point about the UJ's is interesting.

Are the joints either ok or obviously knackered ? I checked the propshaft ones when I did the box by feeling for play whist trying to turn the two halves of the joint in opposite directions off the car. Is this correct ? I also moved the joint through its full movement. There was a slight tight spot ( tighter than at other angles ) but I thought this was the natural angle the joint was running at on the car. Is it ok to change these without having the prop balanced ?

Harvey mentioned the differential mounting. I believe these are known to crack. Also the differential itself but I thought these were very sturdy especially on the 4cyl cars.

Yes I need to change the engine mounting, I presume you can't get these new, so may need to use your vw upgrade!

 

[SydneyRoverP6B]

Hi Pat,

The uni joints should feel consistant throughout their range of movement. If you can feel a tight spot and the joint has been in for a while, then that suggests a potential problem. Do the joints have nipples or are they the sealed for life type?

The n/s rubber diff mount suffers much more so than the o/s. It can also work loose which will allow unwanted differential movement. The differential hanger, the plate to which the diff is attached and which in turn is retained by the aforementioned mounts, can crack adjacent to the mounting points. Again the n/s is more likely.

Is the pinion extension case mount in good order and secure? If you push up on the extension case at this point, does the whole back of the car lift or just the case and tailshaft?

Ron.

 

[pat180269]

Hi Ron

Do the joints have nipples or are they the sealed for life type?

The joints are sealed for life type so presumably original. I have a spare pair of drive shafts off a scrapped V8 ( are they the same ?) ; I'm wondering whether I should change the UJ's and refurb them then swap them over to rule this out ? I could do the propshaft as well they are not expensive.

Its interesting you mention the nearside rear. I have a loud rattling / clunking on rougher roads. The weather here has been very good and I have been driving with the front passenger window open. It can be clearly heard. It almost sounds like the rear wing is flapping about, but its not of course. Could be rear shocks.

I'm going to get under the back end this weekend and have a look. Will take some pictures and have a poke about.

 

[harveyp6]

I happened upon a NOS gearbox; still in the box with rover labels never fitted to a car.

1) The box is noisy in 1st ,2nd and 3rd

If you are in the car with the handbrake on, the engine running, and the gearbox in neutral, and it's noisy right up until you put your foot on the clutch, at which point the noise disappears, then the noise is inside the gearbox, regardless of the fact that it's new. All the other incidentals, like judder and other noises won't have any effect on that and need to be treated as separate problems and dealt with in their own right.

 

[pat180269]

I've only noticed the noise in neutral after a good run after reversing and parking up. The noise is not there on startup or when left idling for an extended period. I've not noticed it driving about but then again I haven't been listening for it.

My overriding thoughts are that either the fault is elsewhere or a large percentage of P6 gearboxes are crap and always have been. A 66K box and a NOS box with the same characteristics.
Illustrating the point further here is a you-tube video of one where the vendor mentions a whining gearbox. http://www.youtube.com/watch?v=fqG1UBLo8Lo

I chatted with a guy at the All Rover Rally at Beamish last month who has a mint 2200TC. I only got a brief chat but he said " they scream their head off in 1st and are only really quiet in top".

I am driving a 2000TC on friday so it will be interesting to compare an earlier car.