Diagram of P6B diff mount needed

[302Rover]

The differential (final drive) pinion housing mount was changed considerably from the P6 to the P6B models. For the 4 cylinder cars it was a short piece of stamped sheet metal whereas the 8 cylinder cars got a long, heavy weldment that traversed the width of the car. Would anyone have a drawing, perhaps from the service manual, or a photo of the P6B mount and how it attaches to the car? If so, would you be so kind as to scan and email it to me? Any help would be greatly appreciated.

Cheers,
Tom

 

[Demetris]

The P6B transverse diff front extension mounting is also used as pick up points for the rear lower suspension arms. Therefore, the base unit is different between the 4 cyl and V8 cars. Only the 2200 models IIRC adopted the V8 rear suspension.
In any case, as i have done the same modification in my car, fitting a complete V8 final drive in place of the 4 cyl one, i can assure you that this is not the source of your problems, as long as the rubber mounting of the diff nose is in good condition.
I pressume that you have checked the output flange of the new gearbox has ended in the same position as the original one, right? Or if it is further back, it doesn't force the joints in the propshaft to work at awkward angles.

 

[302Rover]

The P6B transverse diff front extension mounting is also used as pick up points for the rear lower suspension arms. Therefore, the base unit is different between the 4 cyl and V8 cars. Only the 2200 models IIRC adopted the V8 rear suspension.
In any case, as i have done the same modification in my car, fitting a complete V8 final drive in place of the 4 cyl one, i can assure you that this is not the source of your problems, as long as the rubber mounting of the diff nose is in good condition.
I pressume that you have checked the output flange of the new gearbox has ended in the same position as the original one, right? Or if it is further back, it doesn't force the joints in the propshaft to work at awkward angles.

Hi Demetris,
I'm really just interested in the design for the V8 model diff mount design, not that I plan to incorporate it into my car. It is for that reason that I'd like to see a drawing of the V8 diff forward diff mount.

Regarding your question about the output flange, a new custom prop shaft has been fitted and I paid close attention to drive line harmonics, U-joint phasing, transmission output shaft angle with respect to prop shaft angle, and final drive input shaft angle, as well as prop shaft length. At the time I thought I had got all that correct but given that there is a vibration present, I'm rechecking all my work to see where I might have gone wrong.

Cheers,
Tom

 

[Demetris]

Hi Tom,
Here is something that might help, courtesy of Rover Classics.
Regarding the gearbox mounting, did you follow the complex route of the 4 cyl cars, or the simpler method of the V8s?
You will remember that in the NVH prone 4 cyl cars the gearbox tail was carefully balanced with a coil spring.
I guess that now you have a much more heavier gearbox, and probably a similarly heavy engine?
Perhaps this would upset things and the factory mounting points are not good anymore.
I remember reading that Rover itself had major problems to cancel various driveline vibrations during the development stage.
Maybe now with the new engine / gearbox you have to do something radical reagarding their mounting.
Sorry if i don't sound very encouraging, but it seems to me that you have already covered the obvious easy ones.

 

[302Rover]

Hi Tom,

Regarding the gearbox mounting, did you follow the complex route of the 4 cyl cars, or the simpler method of the V8s?
You will remember that in the NVH prone 4 cyl cars the gearbox tail was carefully balanced with a coil spring.
I guess that now you have a much more heavier gearbox, and probably a similarly heavy engine?
Perhaps this would upset things and the factory mounting points are not good anymore.
I remember reading that Rover itself had major problems to cancel various driveline vibrations during the development stage.
Maybe now with the new engine / gearbox you have to do something radical reagarding their mounting.
Sorry if i don't sound very encouraging, but it seems to me that you have already covered the obvious easy ones.


Hi Demetris,
thanks for the drawings. I'll look closely at them. A quick scan through didn't reveal any information about the mounting of the crossmember to the car. Would you happen to have anything along those lines or perhaps I missed it in my quick pass.

Regarding the mounting, I had to change all that to accomodate the Tremec 5 speed gear box which is quite a bit lighter (as I recall) than the old Rover gear box. And I needed to move the rear mount aft a couple of inches so had to design and build new rear mount structure. The mount itself is a standard Ford rubber mount, not the spring thing that Rover used.

Overall the Ford V8 is about the same weight as the old Rover 4 banger, thanks to the thin wall casting techniques that Ford used plus the aluminum GT40 heads and the lighter weight ancillary equipment such as alternator, very compact starter, etc. And the center of gravity is a bit further aft than the original Rover motor/gearbox assembly. The front end sits slightly higher than before.

Today I bought a new electronic digital level to take a closer look at the angles of the gearbox output shaft, the prop shaft, and the diff pinion input shaft and have discovered a minor angular problem that could be causing some problems. I think I can get the angle relationships straightened out with some minor adjustment of the pinion housing mount height. Plus tomorrow I will take the half shafts in for balancing. We shall see what happens after the minor 'tweaks' are made.

Overall this is not a serious problem and the vibration isn't as severe as it was with the original so-called '4 banger freeway boom' that I lived with for years when I drove the car daily. But never the less I would like to smooth it out.

Thanks again for your insight.
Cheers,
Tom

 

[Demetris]

Hi Tom,
a quick internet seach turned up this website http://www.britishv8.org/articles/rover-p6-design.htm with photos that will give you an idea.
I have also found this: http://www.flickr.com/photos/psycho_milt/7620443932/in/photostream/
This set up is said to improve the refinement of the car in comparison with early 4 cyl models, and i can see why. Mind you, the halfshafts on V8s (or maybe all late models?) were also balanced.

In the 4 cyl P6 almost all the weight of the engine / gearbox combination is supported by the two sophisticated engine mounts. There is only a very light load on the gearbox mounting.
I am not sure if the V8 models respected this kind of balance, but they cannot be too far off.
Anyway, i guess that soon you will find a solution.

 

[harveyp6]

Regarding your question about the output flange, a new custom prop shaft has been fitted and I paid close attention to drive line harmonics, U-joint phasing, transmission output shaft angle with respect to prop shaft angle, and final drive input shaft angle, as well as prop shaft length.

P6 props aren't phased in the normal way, the U/J's are offset from one another by varying degrees according to model, so if you've had your prop built with the joints aligned in the conventional manner that could well be the problem.

 

[302Rover]

Regarding your question about the output flange, a new custom prop shaft has been fitted and I paid close attention to drive line harmonics, U-joint phasing, transmission output shaft angle with respect to prop shaft angle, and final drive input shaft angle, as well as prop shaft length.

P6 props aren't phased in the normal way, the U/J's are offset from one another by varying degrees according to model, so if you've had your prop built with the joints aligned in the conventional manner that could well be the problem.

Harvey,
OK, this is a revelation to me. I had no idea that Rover didn't phase the U-joints in the 'normal' way. I had my prop shaft built with the U-joints all lined up, i.e. phased per conventional practice. Would you have any hints as to where I could find phasing information on both the 2000TC and the 3500 models? Or for that matter, include the 2200 as well. Meanwhile I'll look in my 2000 service manual to see if there are any hints there.

When I take the half shafts in to my driveline shop, I'll discuss U-joint phasing with them to get their take. Off and on I have been wondering about converting the prop shaft to CV joints. Do you have any thoughts on this?

Cheers,
Tom

 

[302Rover]

Hi Tom,
a quick internet seach turned up this website http://www.britishv8.org/articles/rover-p6-design.htm with photos that will give you an idea.
I have also found this: http://www.flickr.com/photos/psycho_milt/7620443932/in/photostream/
This set up is said to improve the refinement of the car in comparison with early 4 cyl models, and i can see why. Mind you, the halfshafts on V8s (or maybe all late models?) were also balanced. quote]

Hi Demetris,
thanks for taking the time to locate this information. I now see what Rover did; i.e. incorporated a massive cross member that provides not only front diff mount but trailing arm mounting points as well. I bet that they also beefed up the local support structure where the ends of the cross member attach to the underside of the car.

Cheers,
Tom

 

[harveyp6]

OK, this is a revelation to me. I had no idea that Rover didn't phase the U-joints in the 'normal' way. I had my prop shaft built with the U-joints all lined up, i.e. phased per conventional practice. Would you have any hints as to where I could find phasing information on both the 2000TC and the 3500 models? Or for that matter, include the 2200 as well. Meanwhile I'll look in my 2000 service manual to see if there are any hints there.

It's certainly in the P6B WM. ISTR the first V8's had one alignment, then after changes to the diff that figure changed. It's a degree of rotation on the sliding joint from what would be considered the conventional alignment. If you read the book all will become clear as far as the alignment as it should be set, but not necessarily the reasons for it.

When I take the half shafts in to my driveline shop, I'll discuss U-joint phasing with them to get their take. Off and on I have been wondering about converting the prop shaft to CV joints. Do you have any thoughts on this?

The P6 halfshafts follow normal alignment. SD1's used CV joints in the prop. Personally I haven't given them much thought.

One thing I would say, having made my own props for various projects, I've never had vibration problems, but those people that I have known that have used "professionals" to make them have had no end of problems, the most recent having been back 5 times before they got it anywhere near right.

 

[302Rover]

It's certainly in the P6B WM. ISTR the first V8's had one alignment, then after changes to the diff that figure changed. It's a degree of rotation on the sliding joint from what would be considered the conventional alignment. If you read the book all will become clear as far as the alignment as it should be set, but not necessarily the reasons for it.

Thanks, Harvey. I'm at a bit of a disadvantage because I don't have a copy of the P6B work shop manual, hence all the questions about the V8 drive line alignment. But given the info that you have provided, I'll try to scare up one locally.

Cheers,
Tom

 

[harveyp6]

It's certainly in the P6B book, 107degrees angular displacement for suffix A diffs, 144 degrees suffix B onwards, but that's on P6B's, in the P6 book it just says line up the arrows on the prop with no mention of any figures.
If nothing else, you can at least see that they're not how you think they would be.

 

[TokyoP6B]

Slightly OT: if you are looking for a diff; James Dean in FL, who coincidentally owns a Red P6 Rover, has sold several NADA V8 diffs on Ebay in the last few years

http://beerinc.com/rstca/parts.html

and Flying Circus, in Durham NC, are parting out a number of P6's; you'll have to call them to get pricing and availability tho', they don't seem to respond to emails

http://www.flyingcircusenglishcars....nd+`item_application`+NOT LIKE+'%Land Rover%'

Graham

 

[So Cal V8]

Thanks, Harvey. I'm at a bit of a disadvantage because I don't have a copy of the P6B work shop manual, hence all the questions about the V8 drive line alignment. But given the info that you have provided, I'll try to scare up one locally.

Cheers,
Tom

I've got the V8 WSM and the parts book

 

[colnerov]

Hi, in Land Rover circles with raised height suspension on coil sprung vehicles if vibration
is encountered a trick is to move props out of phase by any amount neccesary. Not very
scientific I know but worth a stab to see if this is the cause, may even be a free fix.

Colin

 

[chrisyork]

So simply split the prop at the spline joint and move round one spline at a time until the best result is obtained?

Chris

 

[sowen]

I've got a factory Land Rover propshaft that is about 45 degrees out from what is conventionally normal. It even has a master spline so can only be assembled in one position.

 

[colnerov]

So simply split the prop at the spline joint and move round one spline at a time until the best result is obtained?

Chris

That's about the size of it! Except with a land Rover there are 2 shafts. Although it
is the front one that is the problem because of the way the suspension works, the
front diff stays in line and the joint at the transfer box end works though a more
acute angle. There are shafts available that have a double carden joint one end.

Colin