Thread: ZF 4HP Lock up converter

Tony, and all others interested,

I have just spoken with the owner of the last vehicle we modded with 3rd lockup, a D1 4.6, and I was mistaken when I said it didn't unlock from the shift 3rd to 4th.
When driven in 'D', it will shift through 3rd, 3rd lockup, 4th, 4th lockup and is fantastic he says.

The only time it'll stay locked during shifting, is when manually shifted through 3rd to 4th when already locked, IE 85 odd KMH.

I'm reporting this to Andrew tomorrow, so he can get on with fitting these to other vehicles

I'm sending my valve body over shortly.

Hope this clears things up, as I mistakenly said it didn't shift how it should initially, but as usual, my memory is like a sieve


JC

Originally Posted by justinc

Tony, and all others interested,

I have just spoken with the owner of the last vehicle we modded with 3rd lockup, a D1 4.6, and I was mistaken when I said it didn't unlock from the shift 3rd to 4th.
When driven in 'D', it will shift through 3rd, 3rd lockup, 4th, 4th lockup and is fantastic he says.

The only time it'll stay locked during shifting, is when manually shifted through 3rd to 4th when already locked, IE 85 odd KMH.

I'm reporting this to Andrew tomorrow, so he can get on with fitting these to other vehicles

I'm sending my valve body over shortly.

Hope this clears things up, as I mistakenly said it didn't shift how it should initially, but as usual, my memory is like a sieve


JC

Woohoo! What about the $$ (PM if more appropriate)

Only thing is - does the manual shift under lock up present a problem at around 85? Is it damaging or anything? Only reason I ask is because this is a crucial manoeuvre for Tdi owners - when it flags in D on a freeway hill and needs to be pulled back to 3. (I'd assume provided you lifted your foot during the shift it'd be fine)

Also, what speed does the 3 lock up occur? Is it the same speed as 4th lockup or lower?

I'm dropping my auto in about 3 weeks when funds suffice and if its not ball breaking $$ to have the mod done - I'm in!

Originally Posted by justinc

Tony, and all others interested,

I have just spoken with the owner of the last vehicle we modded with 3rd lockup, a D1 4.6, and I was mistaken when I said it didn't unlock from the shift 3rd to 4th.
When driven in 'D', it will shift through 3rd, 3rd lockup, 4th, 4th lockup and is fantastic he says.

The only time it'll stay locked during shifting, is when manually shifted through 3rd to 4th when already locked, IE 85 odd KMH.

I'm reporting this to Andrew tomorrow, so he can get on with fitting these to other vehicles

I'm sending my valve body over shortly.

Hope this clears things up, as I mistakenly said it didn't shift how it should initially, but as usual, my memory is like a sieve


JC

No harm done Thanks for follow up. Now sounds promising. I wonder what will happen when driven in anger in low range etc. And as mentioned before banging it down on a hill when over 85kms. Here is hopeing... PM sent.
I should have a spare auto soon so if not to costly I will get the valve body out and send away for the mod. Tony

Im watching with interest.

I had a play in my 300tdi auto disco on the weekend and even at 100kmh, I can get it to kick back down to 4th no lockup and hold to the point where it climbs to about 115kmh before I couldnt hold it in 4th any longer and it dropped into lock up.

This was up a long hill and as much as a 300tdi pulls it felt ok to me.

I wasnt towing or anything though I wanted to see if it would hold 4th.

I would be interested to see how hard it would be to increase pressure on the relief on 4th so it would hold for a higher pressure as I dont believe lockup clutches are the toughest things in the box.

I get what your saying about the clutch not being under any more load due to it being before the gear train though as soon as it is under any load it will drop back into 3rd or else you will be putting more strain on a clutch that isnt designed to have bugger all load on it so Im still not seeing the point.

Even though it is possible it doesnt mean that it wont damage things.

Im watching with interest and Im hoping my thoughts are proven wrong but I wouldnt be doing it to my $1200 worth of lock up converter until ive seen one working for a decent amount of time.

Originally Posted by mcrover

Im watching with interest.

I had a play in my 300tdi auto disco on the weekend and even at 100kmh, I can get it to kick back down to 4th no lockup and hold to the point where it climbs to about 115kmh before I couldnt hold it in 4th any longer and it dropped into lock up.

This was up a long hill and as much as a 300tdi pulls it felt ok to me.

I wasnt towing or anything though I wanted to see if it would hold 4th.

I would be interested to see how hard it would be to increase pressure on the relief on 4th so it would hold for a higher pressure as I dont believe lockup clutches are the toughest things in the box.

I get what your saying about the clutch not being under any more load due to it being before the gear train though as soon as it is under any load it will drop back into 3rd or else you will be putting more strain on a clutch that isnt designed to have bugger all load on it so Im still not seeing the point.

Even though it is possible it doesnt mean that it wont damage things.

Im watching with interest and Im hoping my thoughts are proven wrong but I wouldnt be doing it to my $1200 worth of lock up converter until ive seen one working for a decent amount of time.

Damo,

I have a 130 Tdi auto customer that has had a lockup conversion done about 180,000km ago, and it was this gearbox we copied the lockup mod from after examining it. ( the box was rebuilt after it overheated. The person who converted it fitted the oil cooler BEHIND the 12,000lb winch)

The lockup in 3rd hasn't caused any issues with the vehicle at all, and if it hadn't got hot, would never have been dissassembled!

I have no hesitation doing it to mine.

JC

Has any one got any more feedback on this mod.

Just about to pick up a low kay one owner Rangie. I am keen to get this done if it works as will have a good spare auto to play with.
Tony

Originally Posted by justinc

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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).

just to nit pick, torque converter lock up is handled by the input speed of the gearbox not the output and the gear selection side that handles weather it can or cant lock is handled as part of the gear selection process which is done by the output speed. In later boxes its also got a balancing act setup on the throttle position sensor so it wont lock if theres too much difference between engine power and trans speed.

Originally Posted by justinc

Tony, and all others interested,

I have just spoken with the owner of the last vehicle we modded with 3rd lockup, a D1 4.6, and I was mistaken when I said it didn't unlock from the shift 3rd to 4th.
When driven in 'D', it will shift through 3rd, 3rd lockup, 4th, 4th lockup and is fantastic he says.

The only time it'll stay locked during shifting, is when manually shifted through 3rd to 4th when already locked, IE 85 odd KMH.

WAG, all theyve done is open a gallery that lets 3rd gear pressure spill to the Tc control bit of the box...

In theory you should be able to set it up so that it locks in all gears..
If you get that right it means that, in theory, when your doing engine braking that it should lockup the TC as soon as your in an over-run condition with enough RPM on the front of the box to make it think that it should be locked up..

I havent tested it but on paper it gets better.... IF youve got it all right it will now downshift and lock under the same conditions soooo you shifting would go

1, 1lock, 2, 2lock, 3, 3lock, 4, 4lock when your accelerating and
4lock, 4, 3lock, 3, 2 lock,2, 1lock, 1 when coming down.

itd be pretty hard on the TC lockup clutch but youd then pretty much have all the advantages of the auto with most of the advantages of the manual.. (you'd still be dependant on good oil and cooling tho)

Interesting, I was recently looking at the possibility of modifying the torque convertor to lock up more under normal driving.

I am not sure if this is possible. Reason being is I have a modified TC sitting in my garage that has no lock up mech at all, but it has a one way plate that is constantly locked under rebutle/deceleration.

I am interested in learning if it is possible to get the tc to 'grip' more under normal driving conditions, to make it more like a manual.
I beleive this would be like a low stall mod if possible?

Basically at the moment I think the tc slips a touch too much all the way up the rev range and I want to reduce that (I know this in theory will reduce torque).

So is there any possible way to modify the TC to say be 80% locked at 1200rpm, 90% buy 2000rpm and 95 at 2500 then almost 100% buy 3000rpm???

Sorry for the hijack, just curios is all!