BW35 vs ZF4HP22

rockdemon

rockdemon

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Staff member
Hi all (especially harvey :D )

As i've just posted in another thread, i'm a little worried by PAE's BW35 behaviour so the time could be coming quicker than i anticipated that i have to do something about it.

Given this I'd like to have a bit of a compare and contrast between these 2 (and any other i've not thought of) replacement options.

BW35 - reliable? standard fitment, would probably be able to get something that is fully recon'd.

ZF - Better ratios, lock up (so better mpg)
I have the BMW version of the ZF with the tailshaft.
Read about some reliability issues.
fitting not straighforward.
couldnt afford to recon, so would be dependent on getting a good discovery/range rover front end and torque converter.
Does it take the standard prop?

What thoughts do other people have on this? Just want to consider all options before i do anything on this front!

Thanks a lot!

Rich.
 
Reconditioned (properly) the BW35 will be perfectly fine, but it will never have 4 speeds with o/d top and a lockup converter.
ZF's give you all that but aren't a straightforward fit, and in most cases they will just be fitted as is, rather than reconditioned first. Costs vary so widely dependent on how much you can do yourself, but I reckon you might get an LDV secondhand box fitted by someone else (including the price of the s/h box) for round about what you'd pay to have a BW35 removed/overhauled/refitted, but that's not really comparing like for like. Personally if you want to go ZF I'd hold on for the LDV box, it makes life so much easier. Going rate seems to be about £400 at the moment for one complete with all (or most) of the bits you'd need.
Your 35 might just need a repair that could be done without removing the box, and continue perfectly for years.
 
Hi Rich

Only bit to add to Harvey's response is that, yes, the ZF does need a shortened prop. However, I do happen to have one in my garage, which you can have on loan to keep the initial cost down. You can replace it later when you have the funds. (I too want to fit a ZF when my BW35 expires!) The other difficulty with the ZF is sorting out the speedo. If you get a box with a mechanical speedo drive (LDV) then I see no difficulty in getting a cable made up to link to the Rover speedo, but there will be a recalibration required. If electronic output then it is simple enough to find a convertor box to drive the mechanical speedo head. I'd take both tasks to a tachograph fitting centre. I've had to do this once with a rather unusual Merc 308 van that I had fitted a reversing gearbox (ie same speed backwards as forwards) a hydraulic drive and a limited slip diff in. It went to Tappin's at Didcot and the whole process was completely routine for them. Lorries tend to be so custom built that this sort of thing happens all the time!

Chris

PS, use the standard selector, if necessary altering the throw ratio by adjusting the drop link.
 
Thanks Chris that's a very kind offer. I'll let you know when I've worked out my course of action. I can't really afford to go the full hog yet so if I can get the bw35 to soldier on I will!
 
LDV is a van manufacturer, which fitted some models with the rover v8. With the right alterations they can be made to fit.

Rich
 
We didn't get a lot of LDV badged vans down here but they were a development of the Leyland Sherpa and we got quite a few V8 ambulances badged as Dafs. The ZF from them seems to be basically a Land Rover/ Range Rover type (it is cranked slightly and has a really deep sump) but it's main advantage over the 4wd and Bmw/Jag versions is that it has an output shaft with a speedo drive and a flange that matches the P6 driveshaft.
 
So the one I'm looking at is out of a jag, are the output shaft flanges interchangeable with 35 or 65 box or am I better of waiting for something else to come up?
 
Could u tell me the modifications needed to fit rich? Is it just output shaft flange and speedo or is it modding driveshafts floor plans and mounting brackets?
 
Believe you need at least the following:

Bell housing and torque converter from range or landrover new mounting bracket needs making.
You need a rwd box for the rear part new prop and probably some adaptor plates too.

I was only starting to get some bits together so don't have all the details...

Harvey or Chris York will know more I think...

Rich.
 
Hi Nick

The ZF box is a real advantage thanks to having an overdrive 4th gear and lock up on 3rd and 4th. Both things that the BW's severely lack.

There are only a couple of cars running with this box so far, so not all the wrinkles are ironed out! The hazards known to me so far are as follows: First you need a cable control box - unless you are seriously into electronics. Some are cable control some are electronic. This applies across all the main sources - namely Rnage Rover / Discovery, BMW and Jaguar. So check whether your Jag box is electronic or cable. Then you need a RWD tail shaft casing. That on LDV vans is the most suitable, it already has a mechanical speedo drive and a compatible prop shaft flange, and the support bracket is the most easily dealt with. But Jag and BMW boxes should be fine provided you get the box end of the prop to go with them. The prop will have to be custom, minimum attention is with the LDV box where it simply needs shortening. Engine end equipment is straightforward - a complete transplant of drive plate, bell housing and convertor from a Range Rover / Discovery. You would be well advised to use the valve block from a Range Rover as that has a lower change up speed setting than other applications. Clearly things like sump, dip stick tube and dip stick may need customising. The bell housing gets very close to the firewall at one location only, this is solved by taking a few ribs off with a grinder. A custom exhaust is also needed at least as far as the first silencer as the box is wider than the standard. Change lever in the cabin is reckoned to be best by lightly modifying the BW one to get the correct throw, although there is one car out there with a Discovery set up - I think it is too wide for the P6 transmission tunnel. My plan for dealing with the speedo would be to give the problem to a Lorry tacho-graph centre. They have systems to convert a prop driven electronic pulse generator into a mechanical drive for the standard speedo head, and I don't think it's worth getting more complex than this.

None of the above is that difficult, but there's relatively little experience out there to draw on for problems.

Regards

Chris
 
I did post details a long while back of somebody offering a complete conversion for 1500 quid. I'll have a search later when I'm not on the phone and see if I can find it.
 
http://www.trademe.co.nz/motors/car-par ... 623227.htm
Thanks a lot for the advise, if u follow this link and check out the q and a at the bottom could u tell me if this would be ideal, I'm not sure about the bell housing of this just yet, I will ask thou.
If its not right if a lt97 bell housing would fit I could put my landrover project on hold for a bit and pinch that, the rest sounds pretty straight forward, what's this I read about adapter plates and spacers? Will these be necessary for what I'm getting and want to do? Also is the torque converter any good to me or could I use a 35 or 65 one? Or even a bell housing?
 
On the face of it, that lot should drop straight in - well nearly! He appears to have everything for the engine back, although i don't know what the prop shaft flange is going to be like on the Jag.

So if you bought this what would you need to do?

1 Swop timing cover for timing cover from your existing P6 engine (the later cover is too long to fit behind the rad)

2 But you'd have had to have that off anyway to change the cam. Now you buy a cam to suit the early cam cover and distributor drive! Good opportunity to change the timing chain for a duplex with steel sprockets too.

3 Swap injection manifold for existing P6 carbs linkage etc. The SU's are amply big enough and nuch easier to set up for a "foreign" engine set up.

4 obtain replacement rocker cover. Wise to expect to change rocker shafts and rockers and hydraulic lifters at the same time.

5 Seller says box is mechanical, so you should just need to modify cable lengths for selector and kickdown to suit new installation plus modify box sump and dip stick arrangement to suit P6 engine bay.

6 Shorten existing prop to suit new installation - poss need new box end coupling?

7 Make bracket to support end of box in tunnel. possibly grind off bellhousing ribs to fit under bulkhead.

8 Make new exhaust from manifolds (ex P6) to front silencer of P6 to fit round box

9 sort out speedo - ?get taco-graph centre to make toothed wheel detector for prop and adjustable electric drive for existing mechanical speedo?

Hows about that - simples :)

Check with local freinds as to whether this work would need engineer sign off for your local rego requirements.

You need to use the ex Land Rover crank spigot, flex plate and TQ convertor. The ZF TQ convertor is not the same as a BW, not least because of the lock up. Make sure that the bell housing offered is a Land Rover V8 to ZF, if so no probs, if not then you need to buy one, but I read it that he had these.

The only thing I can think of that could trip you up is the starter motor installation. I have a nagging feeling that LR bell housings place the starter motor in a diiferent place to the LDV ones I've seen previously. I can't believe that isn't soluble though.

One thing you may find is that a Jag box is likely to have the change up speeds set higher than a LR box. So you might not get access to 4th below around 50 mph! If you come across a scrap LR box a valve block transplant shouldn't be difficult - they invariably fail on the front clutch or lock up arrangement so a valve block is almost certain to be OK in a scrap box.

If the workload on the 3.9 looks a bit pricey, you could always put that to one side until funds allow and use your existing P6 motor in the meantime.

Hope that helps.

Chris
 
There are various lengths of tailshafts, so if you have to change that as well as the tailshaft housing then the box has to be entirely dismantled to do it, plus the main casing may be different and have no provision for the P6B dipstick tube, the valve block will be different as well, it certainly won't have a range control valve, and it may have a vacuum modulator as well as a kickdown cable, which you'll need to plumb in. You're digging yourself into a bigger hole.....
 
Nickthelomas said:
Thanks Harvey, is there a website with listings and prices for overhaul kits for 35 and or 65 box?
Click to expand...

I did list prices in a very recent thread on here.



Gasket, seal & teflon ring kit £60.45
Rear band £37.50
Flexi front band £46.35 (You can use a solid one like the rear band if you have an early servo and want to cut the price down.)
Filter £7.18
Friction plates £2.66 ea, (5 for front clutch, 5 for rear)
Front steel plates (5) £9.50
Rear steel plates (5) £9.50
Diahragm spring for front clutch (wasn't on that invoice) about £12 IIRC.

All plus VAT
 
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