Choices for new auto gear box P6B

mrtask said:
Quattro, you needed to alter the passenger side mount on your RHD car; Ragnar, you needed to alter the driver's side engine mount on your LHD car – correct? Either of you got any photos of what needed to be done and why?
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viewtopic.php?f=21&t=4843&st=0&sk=t&sd=a&start=60#p31196

Have a look here.

I was just wondering if I was the only one with this problem. The engine mount (the welded piece on the cross member) collapsed and the rubber of the engine mount got so hot that it allowed the engine to sag to one side

It was the O/S on my car, i.e. the right hand side viewed from the drivers seat
 
Blueman

I would appreciate a couple of photos please,

1st - the bell housing to body work gap, how close & how much space is there

2nd - the rear gear box mount ( once you have made it up ! )

I'm about to start mine, at least I'll taking the engine out over easter.

A general follow up question, perhaps one for Harvey. Should I fit a separate oil cooler or keep the internal radiator system ?, I read some where that in addition to cooling the hydraulic fluid the radiator also acts to warm the fluid up to the correct temperature when you 1st start the car, not sure I follow that - I would have though the gearbox oil would have got warm enough on its own.

Thanks
 
keanej said:
Blueman

A general follow up question, perhaps one for Harvey. Should I fit a separate oil cooler or keep the internal radiator system ?, I read some where that in addition to cooling the hydraulic fluid the radiator also acts to warm the fluid up to the correct temperature when you 1st start the car, not sure I follow that - I would have though the gearbox oil would have got warm enough on its own.

Thanks
Click to expand...


My personal choice would be to fit a seperate cooler, as the ones in the rad are prone to failure, and the damage that causes to the transmission makes it by far the best thing to do IMHO. The internal one doesn't really heat the trans fluid until the stat opens anyway.
 
I agree Harvey; but I'd also want to see an oil thermostat in the transmission fluid lines to the cooler.

There are some practical issues looming when going down this route though. Anyone upgrading their car to the extent of wanting a separate transmission fluid cooler is almost certain to want an engine oil cooler as well. At that point the limited space at the front of a P6 engine bay is well and truly exhausted. I took two actions to address this.

First up was to remove and discard the radiator cross member. This is bolted in by two bolts only each side and is of such a shape and construction that it is extremely unlikely to add any strength to the shell. I'd welcome any suggestions as to why Rover went to the trouble of installing this cross member in the first place. In practice it seems to act to support the radiator structure after it has aged and started to sag. The solution there is to use an alloy rad of proper construction - not difficult to get knocked up by your local radiator specialist or available off the shelf from Classeparts. It is also likely to be much more efficient at cooling a big engine! The space liberated here is just right to accept a Jag V12 E Type oil cooler which is unusally long and shallow. I angled mine backwards at about 45 degrees.

That leaves a space requirement for the trasnsmission cooler. I produced a revised front undertray by grafting the end sections of a 4 cylinder undertray onto the centre section of a V8 undertray. This provides a couple of lumps outboard of the main radiator air intake which you can then open up to provide a couple of extra intakes. The effect is not dissimilar to the three element undertrays to be seen on modern VAG group cars, and I think improves the appearance of the P6B front end markedly. The extra space at each end of the undertray is then sufficient to mount a couple of small oil coolers in series, again angled backwards to get the maximum size. These draw air through the new undertray openings and exhaust up through the headlamp boxes which already have suitable apertures pressed into them.

With big engine, big radiator and the two sets of coolers all contributing to engine bay heat I took the view that there was then a need to help get rid of all this heat from the engine bay. The circuit racer does this by raising the back edge of the bonnet on its hinges. I didn't think this was acceptable for a road car as engine bay fumes are then able to be drawn into the heater intake. I therefore had a set of louvres pressed into the bonnet down each side. That particular solution is expensive as you have to find a body shop firstly with the vintage style press tools for the louvres and secondly with a fly press big enough to accept the complete bonnet. I went to Aston Martin Restorations in Derby..... I'm sure there must be other solutions along the same lines though.

Chris
 
Reading Chris's comments re. engine bay heat I'm reminded of means used by US muscle car enthusiasts, esp. with big-block applications that generate some seriously high temperatures under-bonnet. They usually wrap the headers in heat-insulating silica-based fabric 'bandage' to lead the exhaust heat, which accounts for most of it, down and back under the vehicle. There are also claims that this improves power and fuel consumption. With very handsome headers like Ragnar's that might not be esthetically pleasing, but then he might not need to take that much action for optimum cooling in the Nordic climate?

I'm also a bit stunned by the idea of a 5,5-litre. What's the estimated output there Ragnar?

In terms of the general gearbox discussion - maybe someone else can shed light on this: I believe ZF 'boxes used with diesels are set up to engage at lower RPMs than petrol ones, which at least in BMW applications are generally revvier than 'our' V8s and thus will have seen less hard action. I don't think this observation is explained by diff ratios. I'm fairly clueless about electronic settings and programming though...
 
Have a chat with Ashworths! I think the Range Rover box has a change up into 4th at a lower engine speed than other boxes. If relying on the valve block, then RR settings are desirable, if using an electronic brain then you can set whatever you like!

Chris
 
Hi

I still haven't come any futher with my project, but I have some comments and answers:

Headers
The pictures below is from when I began to reinstall the 4.6L engine to the car, with the headers and the zf-box, after having driven it with the 4.6
with the BW35 and standard manifold and pipes.

RHS
IMG_1428.jpg


LHS
IMG_1430.jpg



I have never driven the car or even startet the engine with the set up pictured. I got the 5.5L before finishing the installation an startet with that project instead.

Engine
The engine is exciting, and was bought from V8Development some while ago on ebay. I do not know the output, but it shoulf be more than 300bhp and 400-500nm I guess. It depends on the injection/carb setup. The camshaft is a Stealth which is said to have very good idle, excellent drive ability, moderate mid range, good bhp. I used to have a Piper 285 in the 4.6 and the idle was poor, very irritating with an auto.

55Ltop.jpg

55Lbunn.jpg



ZF Gearbox
The rear mounts is done in the similar way that BBLongman used on his car som years ago. But in my case I do not need to increase the size of the tunnel. I'll take pictures when finished.

http://www.geocities.com/bblongman/Gearbox.htm

I have had much use of BBLongmans site when planning and doing this.

Radiator
When driving the 4.6 I used the original radiator, with oilcooler. It was ok, but got a little warm staning in queue in warm days. I then had the standard exhaust manifolds. I have now rebuildt the standard radiator using the original frame, but got it made to a 3 row. Still with the oilcooler. The company that did the job meant it should bi ok for the 5.5L too. The nordic climate includes some days warmer than 30 deg celcius.
 
NZ's TradeMe auction site has a plethora of ex-BMW 4HP22s available at cheap prices. Are these a good starting point for a conversion, having a 2WD back end?
 
Yes indeed, but of course you will need the bell housing, flex plate etc from a Range Rover or Discovery to complete the front of the box. All 4HP22's are cheap to buy. The expensive bit is an overhaul before use! You could try one as found, but auto's are notorious for not liking being stood out of use for any length of time.

Chris
 
I was also looking at an ad for a wrecked Discovery - $400 or thereabouts could secure me 2 4HP22s, a BMW one and a Disco.

When investigating this topic a while back I discovered the following ratios for various permutations of the 4HP22:

2.48, 1.48, 1.00, 0.73 (US spec Rangie Classic)
2.73, 1.56, 1.10, 0.73 (Volvo 940)
2.48, 1.48, 1.00, 0.73 (BMW E30)

Compared with the BW35 ratios:

2.39, 1.45, 1.1 (from Rover factory manual)

I'm not too hot on ratios, and while I can clearly see the difference between the BW35 and the 4HP22, how critical would the difference between the BMW/RR and Volvo versions of the latter be?

And would the valve body off the hypothetical Disco box be required to provide the correct change points?

I'm very interested in the possibility of a new gearbox but of course I need to do my PAS conversion first, and that's been on hold lately due to insufficient funds.
 
The Volvo is lower geared in the three lower gears. So acceleration from rest will be better, but, on the basis that it probably doesn't change into 4th until 40mph ish, the economy round town will be worse. With the Rover V8 low down torque these lower ratios are a bit wasted. I'd go for the BMW box and use the front end and valve block of the Disco.

Chris
 
The three lower ratios of the Volvo are lower geared. So it will be quicker off the mark. But on the basis it doesn't change into top until around 40 ish, the economy and fussiness around town will be worse. And with the low down torque of the Rover V8 that's a bit of a waste. I'd go for the BMW box with the rfont end and valve block of the Disco.

Chris
 
Great reply. Thanks Chris. In any case there are a few of the Volvo boxes about, but it seems that here in NZ by far the easiest to come across is an ex-BMW item. The LR version isn't too hard to find from what I can see, and as I think I said earlier, $400 would land me both. But of course that is only the start...
 
I've come across a number of 4HP22 boxes for sale, quite cheap, with switchable modes (economy, sport, etc).

What's the gas with these? Can they be easily used in the P6 (assuming the correct valve body, tailpiece and bellhousing are in place)?
 
Bit of a brave option. The difficulty is that the electronics to control them is generally buried into the cars wiring loom and or black boxes. It is possible to buy bespoke transmission controllers, but they will then need extensive programming to make your transmission behave as you want it to. An extremely satisfying and worthwhile result, but you need to understand how the transmission is meant to work in detail. If you are into electronics / computing and techy things I can give you more detail. Plus there have been some other threads on this.

Chris
 
Ooooh, thanks Chris, but for now I think it might be safer to stay with the simple version. But you never know, if the right box popped up at the right price...
 
Can anyone tell me why you guys are all talking about using Range Rover bell housings rather than your existing BW35 bell?
I have adaptor plates for 4HP22 to BW35 (used by a number of Stag owners).....cheap and easy.

Adie
 
Wasn't aware there was such a thing. Does the ZF torque converter fit in the BW bellhousing? Where does one find one and what are they worth? And in my case, will you post overseas and do you take Paypal? :)
 
Now the challenge starts

Just bought a 4HP22 box from a 1987 Range Rover only 150,000 KMs on the box no flex plate unfortunatly and looks like no rear end either. but for the chump change of NZ$31 (about 10 pounds) I hopefully can't go wrong.....go wrong ......go wrong,,,,go wrong :mrgreen: So I guess I will have to now get a bit more serious and start to look out for the other bits I need. Any advice???
Bought off our NZ trademe site (ebay equiv) http://www.trademe.co.nz/Browse/Listing ... =276165480

Graeme
 
Well done that man! Sounds like you now need a BMW box as donor for the rear end. Not sure what they will have in the way of speedo drive, but if the worst comes to the worst use a digital take off with a little motor driving the speedo up in the dash. I'm pretty sure we've covered that before in this post, if not I can supply a link. Can't help with the flexplate issue. Worth buying a new one :shock: ? Consensus has been gained elsewhere that the BW selector can be used, with a bit of judicious fiddling to get the throw right, provided you don't mind not being able to manually engage first. Only remaining hazard sounds like getting the control cables made up to the correct lengths.

Keep us posted!

Chris
 
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