GM AUTOBOX

[Deleted]

;
Hi,
Does anyone know if a GM 400 autogearbox as used on Rolls Silver Shadows will fit a Rover 3.5 engine ?
Cheers,
Mike

[harvey]

Later V8 SD1's used a GM box, but it was the GM180.

[Deleted]

Thanks Harvey, That's very interesting information.
regards,
Mike

[Deleted]

My son and I bought a P5 3.5 each from the Club web site back in October. Generally we're quite happy, although as can be seen on various topics on the forum, we've had a few problems.
One car was claimed to have only done 46000 miles, and the other 83000 miles.
On both cars the owners said that they had replaced the autogearboxes with re-con ones, a fact which I found difficult to understand considering the low mileages. ?? That being so, it is also difficult for us to understand why the boxes lack the smoothness of gearchanges ?? Changing up and down is felt very distinctly, particularly going down to 1st when stopping ?? Is this the same for others ? I've owned a few Classics in my time with autoboxes, and I don't recall any that were as bad as these.
I once owned a Rolls Silver Shadow with 125K miles on it with it's original autobox, and it was as smooth as silk. It was impossible to detect gear changes. The box was a General Motors GM 400 3 Speed.
I understand that a GM 180 was fitted to the SDI Rover 3.5's ?? Does anyone have any experience of these ? or know why Rover changed from Borg-Warner on this model ?? Clearly it may be possible to substitute a P5 autobox for a GM 180 from an SDI ?? It could be a better solution ?
Any thoughts anyone ?
Mike

[harvey]

The harshness of the change of the 35box has been covered on here before, it always has a noticable change, but a noticably harsh downshift into first is a classic sign of the pressures being set too high. After setting the linkage correctly and getting the fluid level correct, I would re set the kickdown cable.
A GM180 will give a smoother change, but it's still only a 3 speed, so if you're getting that involved with changing boxes go for a ZF 4 speed overdrive box.

[Deleted]

Thanks Harvey, but we don't want a manual gearbox.
Mike

[Deleted]

Whoops ! Sorry Harvey. I mistakenly thought the ZF was a manual gearbox.!
I read the thread about changing the box to a ZF and it seems very complicated. I'm not sure if that's the answer for us. Is it possible to find out what the gear ratio is on the SDI GM box ?
Mike

[Deleted]

WOW !! I read back on all the related gearbox threads and it is very revealing. It would seem that our
experience is quite common, and lots of alternatives have been sought. Perhaps we'll stay as we are and adjust the pressures etc., and see how we go. It seems a shame that such a quality car was supplied new with a less than perfect gearbox.

[harvey]

What you have to remember with the 35 box is at the time of its introduction to the 3 litre and then the 3.5 is that there was very little other choice available at the time UK wise. America had vastly more experience with autoboxes and we only outdid them when the AP box came out (mini) running on the engine oil.The yanks couldn't really believe we'd been able to make that work.
In the mid 1960's most UK RWD autos were fitted with 35 boxes, from the small stuff, early ford escorts, cortinas corsairs etc., right up to the XJ6 and plenty inbetween, even the FWD wedge princesses had a transverse version.
As for the 35 box in the P5B, a good road test by someone who knows what they are doing adjusting the kickdown cable should be able to get the box running and changing fairly smoothly.
As for the GM box, top gear will be the same ratio as the 35 box (1:1) and the intermediate ratios will be set to match the V8 so no real advantages there.

[Deleted]

Many thanks Harvey, You have been most enlightening.
Whererabouts are you in Essex ??
Perhaps we could meet when the spring/summer comes ??
Mike and Richard.

[harvey]

Hi, Mike and Richard, I've sent you a personal message.

Harvey.

[dorsetflyer]

The P5 3litre DG auto gearbox when set up correctly, is much smoother than the BW35.
The BW35 was also used by Rootes in the Singer/Humber range of both medium and large saloons.
It was also used on all the models of BL's 'Landcrabs' which came before the 'Wedges'. I had one of the 'Landcrabs' with auto, and suprisingly it was the smoothest of any type of 'classic' car I have driven with auto fitted.

[harvey]

The DG box is definately far smoother than the 35 box, but being cast iron it's bl**dy heavy, and I've found it a pain to work on although I only have limited experience with them. I'm sure once you get to know them they're OK although having said that the last one I sorted had been recently overhauled by a so called specialist.
The list of vehicles fitted with the 35 box is surprisingly long once you start looking and includes lots of BL, ford volvo mazda taxi and scimitar to name a few and all with the same basic box

[Deleted]

Hi Harvey, message not yet received Mike

Hi John in Weymouth. Yes, you are right. Also the Triumph Stag had a BW 35 on MK I's, and a BW 65
on MK 2's. The workshop manual says it was changed because the 65 was much 'lighter'. The Stag in fact drives very similarly to the P5. And yes, again you are right on the landcrab models. I have a Wolsey 2200 Auto, and that drives very nicely, although it's only done 26000 miles. (Please don't think I'm bragging, but I also own a MK 2 Stag.) Mike

[harvey]

]Hi Harvey, message not yet received Mike

Well it has been sent, check your private messages (not email) next time you're on, if still lost in cyberspace I'll re send

All the best, Harvey.

PS, as for stags I know someone who restores those and he keeps trying to drag me into working on those for him, so far I've resisted but he's so d**n persistant I just have to keep away.He does make a good job of them though.

[Deleted]

Hi Harvey,
I don't know how to find your e mail

[Deleted]

Hi Harvey,
I don't know how to find my private e mails ??
Mike

[harvey]

If you look on the index page in the Info centre, forum statistics, down on the RHS is "your private messages", click on to find.

[dorsetflyer]

Nice to now you have a Wolseley 2200 Mike. One of my local local club members has one and they are nice. I have not long moved my 'Landcrab' on as I had someone who wanted it, and I couldn't refuse him.
Like yours my one was low mileage (27K) from new, having covered only 5K in the first six years.
There are quite a few Wolseleys in this area and some of them are absolutely mint. You only see them at 'Landcrab' meets.

[Deleted]

Sorry Harvey - I must be thick !!!! Where is the info centre ?? Forum statistics I'm lost !!
Mike

[Keith - Portsmouth]

Hi classicgreendogs,
go here... roverp5.proboards31.com/index.cgi

scroll to bottom of page
at the bottom of the page you will find 'Info Center'
within 'Info Center' is a box headed 'Forum Statistics'
to the right of this 'Forum Statistics' box it says 'Your Private Messages: 0 New: 0'.
Click on either of the numbers (zeros in this example).

Happy New Year, Keith.