Thread: ZF 4HP Lock up converter

Tony,

The mod requires the valve body separator plate to be machined/ drilled slightly, and I am led to believe that there are a few differences in the landrover/ range rover 4HP22 over the years that mean some valve bodies aren't easily modified.
I had one done recently for a customer and it involved using a Jag XJ40 valve body, modified plate etc behind a 3.9V8i. It works well, but will not unlock 3rd when it shifts up to 4th at high road speeds. It shifts a little harshly for my liking (3rd lockup to 4th lockup straight away). This could be a problem in low range, as the shock load could possibly do some damage . This problem will be dealt with with the next one he is doing for my LSE.

Andrew and I were only talking about this today.( Small world) He and I both share the same trans builder in Melbourne, and they have only done a couple so far, 1 of them for me. I'm sending them another valve body for modification so when I finally get round to fitting the Tdi and auto to the LSE....

JC

JC

Originally Posted by justinc

Tony,

The mod requires the valve body separator plate to be machined/ drilled slightly, and I am led to believe that there are a few differences in the landrover/ range rover 4HP22 over the years that mean some valve bodies aren't easily modified.
I had one done recently for a customer and it involved using a Jag XJ40 valve body, modified plate etc behind a 3.9V8i. It works well, but will not unlock 3rd when it shifts up to 4th at high road speeds. It shifts a little harshly for my liking (3rd lockup to 4th lockup straight away). This could be a problem in low range, as the shock load could possibly do some damage . This problem will be dealt with with the next one he is doing for my LSE.

Andrew and I were only talking about this today.( Small world) He and I both share the same trans builder in Melbourne, and they have only done a couple so far, 1 of them for me. I'm sending them another valve body for modification so when I finally get round to fitting the Tdi and auto to the LSE....

JC

JC

Thanks JC Let me know how they turn out. I wan't this mod in the RRC I'm Slowly building up now. Will have Matts old Eaton blower on it with 4.11s MDs ,etc so a very sharp change into 4th in low range would be very bad Lets hope they work out OK. Tony

No Probs Tony, I don't forsee any dramas with the next one, as the trans people can easily sort it now they know about it. (I think I was a bit of a lab rat come to think of it...)
The difference having a 3rd lockup is fantastic, the heat buildup is vastly reduced, and you can tow all day in 3rd gear which is 1:1.
We also fit P38a trans coolers to the D1, they fit perfectly and effectively almost triple the capacity of the cooler.



JC

I am a bit sceptical about it due to the lockup clutch wont take much punishment before it craps itself.

In electronic boxes it is much easier but in a purely Hydraulic box it is hard to control unless you can some how fit an electronic servo to the port which activates the lock up clutch.

This is pretty popular with the Jeep fraturnity but I never thought it to be of that much advantage.

Originally Posted by justinc

No Probs Tony, I don't forsee any dramas with the next one, as the trans people can easily sort it now they know about it. (I think I was a bit of a lab rat come to think of it...)
The difference having a 3rd lockup is fantastic, the heat buildup is vastly reduced, and you can tow all day in 3rd gear which is 1:1.
We also fit P38a trans coolers to the D1, they fit perfectly and effectively almost triple the capacity of the cooler.



JC

Sounds Good I'm almost exited Locking 3rd + big cooler will make it great for my use here. We fry autos very quickly out here. Tony

Originally Posted by mcrover

I am a bit sceptical about it due to the lockup clutch wont take much punishment before it craps itself.

In electronic boxes it is much easier but in a purely Hydraulic box it is hard to control unless you can some how fit an electronic servo to the port which activates the lock up clutch.

This is pretty popular with the Jeep fraturnity but I never thought it to be of that much advantage.

Interesting you say that. I had the same concern at first but should not be under any more pain as is at crankshaft side so torque is similar. Just will cut in more often. Controling is yet to be proven by the looks of it. Would be a huge advantage as mentioned with heat and direct drive when needed for towing duty. Also would make a ZF feel like a six speed box under light use. Tony

When I suggested this a few months back I got a response as if I was some sort of moron.

Interesting you say that. I had the same concern at first but should not be under any more pain as is at grankshaft side so torque is similar. Just will cut in more often. Controling is yet to be proven by the looks of it. Would be a huge advantage as mentioned with heat and direct drive when needed for towing duty. Also would make a ZF reel like a six speed box under light use. Tony

It'll still lock at the same speed as 4th locks up too, so I was told by a ZF builder who said they could do it.

The mod requires the valve body separator plate to be machined/ drilled slightly, and I am led to believe that there are a few differences in the landrover/ range rover 4HP22 over the years that mean some valve bodies aren't easily modified.
I had one done recently for a customer and it involved using a Jag XJ40 valve body, modified plate etc behind a 3.9V8i. It works well, but will not unlock 3rd when it shifts up to 4th at high road speeds. It shifts a little harshly for my liking (3rd lockup to 4th lockup straight away). This could be a problem in low range, as the shock load could possibly do some damage . This problem will be dealt with with the next one he is doing for my LSE.

I'm very interested in hearing how you go with this. Please keep us updated.



Anyone who has had a manual knows that you can pull all day up hill down dale in 4 gear 1:1, It'd be great to have this ability on the autos too.

Originally Posted by Rangier Rover

Interesting you say that. I had the same concern at first but should not be under any more pain as is at crankshaft side so torque is similar. Just will cut in more often. Controling is yet to be proven by the looks of it. Would be a huge advantage as mentioned with heat and direct drive when needed for towing duty. Also would make a ZF feel like a six speed box under light use. Tony

Unfortunately, this is only possible in the electronic boxes, where the ecu tells a solenoid to activate the lockup... In the earlier hydraulic controlled boxes, the lockup clutch is ultimately controlled by the trans governor, or basically the rotational speed of the gearbox output shaft. This means, for example, that you will only get lockup at say, 85kmh. So, if you are doing 85km/h in 3rd, it will lock up (with the modified valvebody).
The other drawback with this system, is that the bigger the tyres, the LATER actual road speed the lockup will engage. Again, output shaft speed is the mitigating factor. If you were to fit Defender high range gearing and use, say 32 or 33" tyres, it would be back to what it would shift like with standard gearing/ tyres. (Well, closer anyway.) I was about to experiment with heavier governor weights etc in my RR trying to get it to lock up earlier when I fitted the Isuzu, but got sick of fitting a gearbox to it every 12,000km...

The major advantage here is that the little 3.9 is way out of its torque band towing at 100km/h in 4th (2200rpm), but is pretty happy at 3000rpm in 3rd lockup (1:1).

JC