ZF 4HP22

Brown Rover completed what in essence amounted to the maiden post-ZF run yesterday, with its attendance at the combined Canterbury car clubs Xmas rally. Unfortunately there was no real opportunity to stretch the ZF's legs and find out what difference the new 4th gear is going to make to the fuel consumption. The route to the destination was hilly, twisty and slow, and I was carrying a substantial back seat cargo of overweight male flesh - about a quarter ton of it in total. I brim-to-brimmed the tank and I'm actually embarrassed to tell you what the final figure was, but the ZF was responsible in part due to the fact that I was gunning it up the hills just to savour the new experience of a gearbox that shifts up and down to suit the occasion. No more "you're moving, you shall have top gear".

Still some niggles to solve, though. I've got 4th gear using the LR valve body now, which is a relief, and I'm experiencing very nice shifts up and down the range. But having had torque converter lockup at about 65mph with the BMW valve body, I now appear to have lost it again. Still something not right with the LR body? I'm appealing to higher authorities before I proceed, but I've resigned myself to pulling the damn thing out again at least one more time. Secondly, I think I might have to install a proper oil cooler instead of relying on the original P6 in-radiator cooler. It was a hot day, high 20s, the gearbox was working hard, and towards the very end of the journey there were gentle indications that it might have been getting a little overwarm. A couple of delayed upshifts and one clunky downshift on the home stretch ruined what was otherwise a perfect performance (torque converter lockup excepted).

Nevertheless, the ZF is rapidly proving to be a huge advance over the BW35. The car is quite transformed.

994059_10200899755003099_597379045_n.jpg
 
Oh grumble! Good to here that you can now test run all the changes you make, though.

Who did the work on the LR valve body - and what was found wrong? Valve bodies truly are a black art to me! I can follow what you've done to the innards of the box and might just be able to do that myself; but the valve body...

Chris
 
Hi, Warren, I think that is a good call on the separate oil cooler. In a Range Rover which has
a 4 row core rad they still kept the oil cooler out of it, plus with the bigger pan on the box
may allude to the ZFs Achilles heel, oil temperature affecting change quality.

Colin
 
I have a 75 cooler sitting in the garage, so I'll see if it fits in the space available and go from there. Plumbing the lines up to the existing in-radiator cooler was always meant to be a short term solution, just to keep things simple whilst I was trying to get the car back on the road.
 
Hi Warren,

Why don't you omit the inbuilt cooler within the radiator and give your ZF a dedicated radiator of its own. I run a dedicated cooler for my Rover's uprated transmission, makes a big difference when you are driving around in traffic on a hot day, both to the transmission and to the engine temperature.

Ron.
 
That's exactly what I'm doing, Ron! Piecing together the parts as we speak and attempting to mount the ex-75 cooler. I might not get it finished this weekend though - I've come down with a rotten cold, damn it.
 
Hi Warren,

Regarding your ZF not shifting into 4th. I had a bit of a squizz to see if I could find out some information, so as to narrow down what the cause might be, and came across this Land Rover thread. The OP was having similar issues, and in his case the cause was the torque converter, which required overhauling.

http://www.4x4community.co.za/forum/arc ... 89511.html

There is also a discussion on the lock up facility, and the circumstances that will allow it to occur.

Hope it might be of some help to you,
Ron.

P.S : Hope that you shake your Summer cold soon!
 
Summer colds are at epidemic proportions in Christchurch at the moment, just about every one I know has had or has one including myself (twice) however I am sure the worst part of it is that Warren wont be able to enjoy his P6 to the same extent he might otherwise have, though having found his 4th gear maybe some compensation....just needs to sort out that lockup. The best victories are always hard fought so they say.

Graeme
 
Hi Ron, and thanks, but I've solved the 4th gear problem in the last couple of weeks, and it didn't have anything to do with the torque converter, which was professionally rebuilt before installation. A process of elimination unearthed a valve body setup problem: now sorted. I pushed through the pain and installed the oil cooler, but damn this summer cold!
 
Well, a flat road cruise this time, and mixed results. During a 100 mile round trip the car ran like clockwork, but there was still no sign of torque converter lockup. It was there at about 65mph with the BMW valve body, so a smart cookie can see where this is leading. The other disappointment was the fuel economy. A brim-to-brim fill calculated out to 20.5 mpg, which makes me unhappy. Dunno why, the last open road trip with the BW35 gave me 25.5, and the engine hasn't been touched since. Anyway, that gripe belongs in the Engine section.
 
Summit don't add up in there Warren, lockup cant be blamed at all as after all the BW doesn't have it either, mmm a bit of head scratching sounds in order.

Graeme
 
I'll start with the basics there: timing, air filters, etc. The engine seems to be running beautifully, but something has gone awry with the fuel consumption since that last trip with the BW. The fuel pump is leaking again from the temporarily bodged up inlet, but I don't believe it dribbled a gallon or so onto the road in a 100 mile trip.

The lack of lockup is pissing me off, but I'll get to the bottom of it yet. I know the torque converter does lock up, so it's down to the valve body again. I've sought advice from the forum's ZF guru and we'll go from there.

That's a Rover for you. Lots of pain for a little pleasure, but I can tell you it is nice to be out on the open road in a P6. The ride quality is unmatched, and sailing along with the V8 thrumming is hard to beat.
 
You've given me a sense of hope, Chris! It might have been the cold getting the better of me, but I was feeling a bit despondent when the calculator returned that result. It was piss-poor consumption for such a flat, straight trip. I was checking the oil cooler connections at our destination when I noticed the dribbling fuel pump (there's some history here, so no, tightening the connection won't do!). Thinking about it, the block was a bit damp behind the pump, so perhaps it was spraying backwards under pressure? A certain amount was dribbling onto the cross member, but it's hard to estimate exactly how much petrol is being lost because it evaporates so quickly, especially on such a nice warm day.

Anyway, I hope you're right. All else being equal, the ZF should be returning BETTER fuel economy, not worse! I've dropped at least 5mpg though, and this is with an engine that was thoroughly tuned just prior to the BW35 shedding its innards.
 
Could the increase in fuel consumption be down to the fact that the gearbox shifts down the gears in corners so you're accelerating harder in a lower gear on the way out than with the BW?
 
Hi Warren,

Maybe the ZF absorbs more engine power, but then you won't know for sure until the fuel pump stops leaking petrol. The seal is between the olive and the seat, so have you tried using Permatex #3 on the olive? It is fuel resistant and will fill any irregularities thus leading to a fuel tight seal.

Ron.
 
Hi Ron, at some point in the dim dark past, the fuel pump was vandalised by a careless somebody who cross-threaded the inlet. It held for an unknown number of years until I noticed it leaking and attempted to tighten it and discovered the crime. At that point I took it out and temporarily bodged it up with Permatex and thread tape, which has lasted a year or two, but it's now leaking again, which I noticed on the weekend when checking my newly installed oil cooler, and possibly badly. It's via the thread, rather than the olive and seat. Anwyay, it's the first thing to eliminate in the quest to get to the bottom of the poor fuel consumption.

As for the ZF, things should have been much better on Sunday, which involved a straight flat run with the car sitting at a steady speed in 4th gear nearly the entire distance. Remember, we're dealing with a much more modern transmission, the efficiency of which should be better than the BW35. This is borne out by the behaviour of the car in the lower gears. It feels much more responsive and is noticeably quicker off the mark than with the BW35 (ghce will verify my claim). Torque converter slip is much reduced compared to the BW35. Accelerating out of a bend with the BW35 involved the car staying in top gear and using torque converter slip to accelerate; the ZF changes down to the appropriate gear and maintains a much more direct connection between the engine and rear wheels. This will improve efficiency, not reduce it. In this respect, think of the ZF as sitting halfway between the BW35 and a manual transmission. The BW65, from my small experience, occupies a spot on the line somewhere between the 35 and the ZF.

As you will all have experienced, it doesn't take much to upset the fuel consumption of an elderly carburettored V8. It's possible, going by the damp block, that quite a lot of petrol was leaking out of the connection at high speed, so I'll place my faith in Chris's claim that this could be enough to ruin my mpg figure. It has to be fixed, anyway! If the fuel consumption doesn't improve after that, I'll start working through the rest of the checklist.

As for my other outstanding ZF-related problem, the lack of torque converter lockup on Sunday was annoying and rather disappointing. Having narrowed it down to the Land Rover valve body (i.e, lockup was present at 65mph when using the BMW body), Andy (eightofthem) and I are working towards a solution in the background and I'll report here when we have it sussed. This project is determined to fight me to the very end! However, I wouldn't have learned anything if I hadn't encountered problems, and the knowledge I've pieced together is freely available to help anybody else who wishes to undertake the conversion. It's a pity I'm so far away from most of the Forumites. It's an open invitation to anybody passing through to come and sample my much transformed car (but do wait until I've got the lockup icing slapped on top of the ZF cake).

Yet again, I'd like to draw attention to the key people without whose help I wouldn't have got this far. On the forum, I can't sing the praises of eightofthem highly enough. Andy stays pretty quiet around here, but in the background he has been the font of all knowledge and advice when it comes to the ZF 4HP22, and I simply don't know where I'd be right now without him. I'd like to nominate him for Member Of The Year. Dakota Digital must be mentioned too. Their customer service was outstanding. The original speedo adapter unfortunately had a faulty output motor, and Dakota immediately had another one on its way to me, no questions asked. They provide a very effective, easily installed solution to the ZF speedo problem, and they stand by their product. The third essential link in the chain was John Weir, my mechanic, who built the very clever custom crossmember that allowed the ZF to be bolted to the existing transmission tunnel brackets (trimmed just a little for clearance) and then sailed through NZ's strict modification inspection process. Just remember that John has all the details on file and will build a replica for anybody who wants one.
 
WarrenL said:
I can tell you that at 65 mph with the torque converter locked up, the car is sitting on about 2100-2200rpm. Third, the same 1:1 as the old third (top) gear, has now been relegated to roaring revs kickdown overtaking duty. It's an amazing difference with the new top gear - a quick kickdown to third is enough to demonstrate the difference between old and new.
Click to expand...

Having just purchased a 1987 E32 BMW 730i, a can vouch for your claims of 2100-2200rpm at 65 mph for the ZF 4HP22. Indeed at 70 mph I noted 2300rpm on the tachometer - very impressive 8) It was great for me to finally test out the ZF 4-speeder in a coventional car, instead of a Land Rover. As you say Warren, gear changes are almost imperceptible, unless you really concentrate of course. On the BMW I found that the torque converter 'lock up' is variable to where the throttle is, and also what type of road is being used. Sometimes it would lock-up at 45 mph, and sometimes at 55 mph - both on part throttle input in economy mode.

Naturally as the BMW has an engine of completely different character to the Rover V8 (6-cylinder, 197 bhp@5800rpm, 203 Ib ft@4000rpm), I suspect the ZF would be more suited to the high torque at lower revs of the RV8. Though I'm guessing the BMW was really engineered for high-speed autobahn cruising, as I noticed it coming alive from 90 mph upward :shock:

But overall a delightful gearbox is the ZF 4HP22 - which must surely be a boon to any car.
 
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