ZF 4HP22

I think the lock up point of 80 KMH from the discovery box is probably the way to go with lightness of the p6 body and the available low rpm torque, it seems to me that the standard 100 KMH of the Beema box would be as good as useless for fuel efficiency and reduced rpm.

Graeme
 
Can you actually express it in terms of particular speeds, Graeme? Those values are going to be affected by everything in between the gearbox and the road; i.e. the diff ratio and the wheels/tyres. But regardless of that, I'm using the Rover torque converter, so theoretically I'll get lockup at a lower road speed than the Beemer unit provides. As far as the change-up to fourth goes, the Rover valve body will cause upshift at a lower speed than the Beemer, and that suits both me and Brown Rover.
 
I would think that the discovery road to rpm speeds would be relatively close, as you say the lower rpm in the p6 would suit you as it would me.
 
KiwiRover said:
The Rangie (which has the ZF) simply will not select 4th below 50mph so it's effectively a 3spd around town but once on the motorway it will sit at about 2200rpm at 65mph. Lovely.
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What sort of hysteresis is there, Al? What I mean is, once in 4th, how low will it hold the gear before changing back down to 3rd?
 
I think it's pretty much set to 50mph and will drop back to 3rd if the speed drops below. It does suggest in the owners handbook that if a faster getatway is required, you should manually select 3rd so I'm not sure if this affects the shift points but it does seem to take off better.
 
WarrenL said:
Yes, the BMW box is my primary donor, Chris, due to its low mileage and tail cone configuration. The current plan is to transplant the Rover valve block into it.
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If you use the rover valve block to replace the BMW valve block, you will also have to change the governor, as they are different.
Also if you have not already looked at them, the oil pump,"A"clutch and "B"clutch should be looked over, as these seem to bear the brunt of the majority of worn items that I have seen.
If all is well with them, the most it will set you back is time and a front cover gasket.
 
Thank you, eightofthem, that is very good advice. I'm planning to strip the Disco box as a kind of practice run, and if it proves to be within my powers I might even transplant the Beemer guts into the Disco case. This would save me having to have the Beemer case machined for the inhibit switch. There will be ample opportunity to inspect clutches, etc, if this is so.
 
Always good to practice :wink: .
The only real issues in stripping it down are-
Removal of the circlip that holds "B" clutch in place
And the removal of the eight or nine rubber seals that lurk under the valve block, you cannot remove anything
Aft of "B" clutch without removing the front four, and "F" clutch will not come out without removing the rear four or five.
They are a real git to remove without the correct tool, but there is a way, and I will send you a P.M on how to.
( you will need new ones though )
I do not know what BMW the box came from, but the gear sets do also differ from the land rover/ range rover ones.
You will have to check them out if you are stripping them.
 
The box came from a '92 BMW E34, a 525. Just over 120,000 kms when it was squashed. In what way are the gears different? I did a bit of scratching around and found the ratios are the same on the Disco and E34 boxes.
 
You have to remember these boxes were fitted to the whole range of bmw models
From 318, 535 , so the ratios did change, i think i still have a set from a csi highline, i will have a
Look at that and compere it to a land rover, and post some pics to show the difference

One more thing to remember, if you put the bmw internals into the rover case
You will need to change the park pawl arm
The rover pawl is thicker than the bmw, so the tail cone will not fit.
The rover is a heavy beast, so they gave it a bit more strength.
It is an easy swop.
 
You sure about those ratios? A couple of years ago, when first embarking on this train of thought, I compiled this list from various sources:

2.39 1.45 1.00 :( BW-35
2.48 1.48 1.00 0.73 Discovery
2.48 1.48 1.00 0.73 RR Classic
2.48 1.48 1.00 0.73 BMW E30 318
2.48 1.48 1.00 0.73 BMW E34 525i
2.48 1.48 1.00 0.73 BMW E34 535i
2.48 1.48 1.00 0.73 Jaguar XJ40 3.2 auto
2.45 1.45 1.00 0.69 Volvo 940 (1)
2.73 1.56 1.00 0.73 Volvo 940 (2)

With the notable exception of the Volvo, the differences were all in the final drive ratio.
 
I know there are variations in the part numbers, as i said i wil take a look at the ones i have and compere
It is no problem to swap some parts over , as most of the internals are the same
You do have to check the number of clutch plates qnd frictions, as these vary,mainly in the front clutch packs
But you only need to check those if you are ordering new ones.
If you have info regarding ratios in black and white for varios models, then dont worry yourself over my comments.
 
I was wary of questioning your far greater knowledge in these matters, but most of those ratios I gathered up from the Haynes manuals and their like, down at the city library one night when I took my son in for some kids' thing and had time to kill. As I said, the principal difference between the various Beemers appeared to be the final drive ratio.

My present plan is taking shape as thus: open up the Disco box and remove the valve body for transplant. I'll then play with it a bit and decide if I'm up to the task of transferring the BMW guts into the Disco case, or whether I should just get the BMW case tapped for the inhibit switch. If transferring, I'll pay attention to clutches etc, and decide if they're worth replacing while everything is apart.
 
Question away, I am no expert.
I am always keen to learn new things, and this is what the forum is for.
Don't be afraid to take them apart you will feel better for it knowing that all is well after all your graft getting it all this far
If I get time on the weekend, I shall send some pictures your way :wink:
 
Alright lads, here's a matter that brought me to a temporary halt while dismantling my ZF gearboxes (see my "step by step" thread). The little rubber washers in the galleries above the valve body won't come out. We've already established that they cannot be removed intact and must be replaced, but I can't shift them at all! Even with a newly and specially acquired pick I can't get enough purchase under the edge of the damn things to pop them out. It appears to me that I have more chance of accidentally scoring the side of the shaft than getting the washer out.

I've thought of trying to squeeze or tap the head of a flat head nail into the washers, which might allow me to lift them out. Before I try this, is there anybody with a better idea, or who thinks this is a bad one?
 
Maybe your pick is at fault? but I can not really say as I have not seen the insides of the box yet. There ate different styles of picks or potential picks out there from different industries, mechanical, electrical and even dental perhaps it is a specific head shape?
I am sure wise hands on auto box people will have the answer for you.

Graeme
 
A poor workman always blames the tools, Graeme. It's a proper mechanic's pick, bought yesterday. However being a point, you can only get it under the inside lip of the washer at one point, and this isn't enough to lift the washer free. They're damn tight in there. The pick just pulls out and jerks upward, running the risk of gouging the bore. I figured a flat nail head of the right size might do the trick if it could be persuaded under the inside lip of the washer. The even pressure all around the circumference might assist in lifting.
 
Warren,
The Pick will lift them out, try piercing the seal from inside.
IIRC they are about 6 mm thick.
I also had success with a self tapping screw.

Jim.
 
Don't know why I didn't think of a self-tapping screw, Jim. I've got a whole ice cream container full of the damn things. I'll give it a go.
 
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