ZF4HP22 Conversion

[BartStag]

Hi everyone,

I hope that all are well.

I wonder if anyone can offer some advice regarding the ZF4HP22 conversion that I am currently doing.

I would have loved to engaged Clive Tate to do it as his reviews are really good, however the financial effect of the pandemic and the fact that the Stag is a driver not a show piece have led me to take on the conversion myself as I don't think I would ever get the money back.

I have started with a ZF4HP22 gearbox & torque converter from a 3.6 Jaguar XJS, I purchased an adaptor plate and have successfully fitted that. I have successfully fabricated a new gearbox mount, gear linkage etc and have found solutions for the inhibitor & speedo.

The car now starts and runs, selects forward and reverse gears however I am having a problem with the converter hitting the bell housing at the pump end? When I set it up I left a clearance of 2mm between the flex plate and the converter mounting plates. I have 2mm spacers welded on the converter to facilitate the converter clearance and when the box is bolted up without the converter to flex plate bolts fitted the converter spins freely. I am afraid that if I remove the welded 2mm spacers the pump to converter lugs will not engage properly?

I have even gone to the lengths of removing the sump and renewing the crank thrust washers and now have a clearance of 0.004", so I'm right at the low end of the tolerance of 0.003 to 0.011"

I am starting to wonder if the converter for the 3.6 Jag is the wrong converter to use? I understand that there are three versions of the 4HP22 converter available, can anyone offer any advice on the correct converter.

Any help or advice would be much appreciated

Best regards

Steve

[alan_thomas]

I have done a couple of these ZF4 conversions making all the parts required. Did you make sure that when the Bellhousing (I assume one from a BW35) was bolted to the body of the ZF with the new adaptor plate that the TC was not rubbing on any part of the bellhousing.with the TC fully pushed back towards the pump.
The best way of checking this is to stand the ZF on it's Propshaft flange with the TC engaged. With it vertical the TC should be able to freely turn without touching any part of the Bell or it's mounting bolts. The first one I made touched and I had to Flycut amm of the plate I had made and machine down the 5\16 cast bosses on the inside of the bell by a further mm. Only then did the TC miss everything. If you have to change something in this area you will have to respace the flexiplate.

Alan

[BartStag]

Hi Alan

Many thanks for getting back to me.

Yes prior to undertaking the project I did a fair bit of research and when fitting the converter inside the bellhousing I did exactly what you suggested, box upright on the rear drive flange and ensured that all three stages of the converter had engaged. Initially I had to do some trimming but I eventually got it to spin freely with no fouling. When I started the car I could hear it chafing so the box came out again and I reduced the spacing lugs that I had welded to the front of the converter to give a 2 to 3mm clearance between the converter and the flex plate. When the box is bolted in position before the converter to flex bolts are fitted the converter spins freely and you have to lever the converter forward to meet the flex plate.

I have read somewhere that the torque converter from the jaguar 3.6 is just too big? I understand that there are three converters that will fit the ZF4HP22 and I'm wondering if the physical size of the converter is the problem, have you fitted a Jag 3.6 box with a three bolt converter?

Another thought I had was that the flex plate may be weak and allowing excess movement, when the box is out all clearances are good it's only when its under load that the chafing occurs. the crank end float is at 0.004" so at the low end of tolerance so It's becoming a bit of a brain teaser?

Steve

[Seaking]

Steve have a look through this post first picture will give you a clue

https://www.google.com/url?q=https://www.socforum.com/forum/forum/stag-owners-club/soc-forum/24761-my-zf4-conversion&sa=U&ved=2ahUKEwiik_P14LT3AhX_QUEAHQXtDuoQFnoECAIQAg&usg=AOvVaw3g9l7NDiW8F8AQOEQPSE5S

[alan_thomas]

Does the rubbing noise definitely come from the rear of the TC? Because I had another clearance problem between the flexiplate and the engine plate as follows.
Did you use the std holes in the flexiplate and weld new bosses on theTC or did you use the existing bosses on the TC and drill new holes in the flexiplate on a smaller PCD to suit the ZF TC?
If the later I had to buy ‘low profile’ Allen head bolts as the bolts on the smaller PCD were rubbing the engine plate

[BartStag]

Many thanks for your suggestions and the attached link from Glenn. Early on I identified that the converter was fouling near the pump and have done exactly the same and sanded the protruding bellhousing & bolts as per the photos.
It was interesting to see the information about the three types of converter and that the large Jaguar one would not fit, does anyone have any information on the converter sizes, is it a case that the large jaguar one will not physically fit in the bell housing, or will it fit but rub?
I used the existing converter bolt mounting points and drilled the flex plate as per Glenn's photos. I have checked the converter securing bolts are not rubbing on the adaptor plate, rather than cutting the adaptor plate as someone has done in the photos I have used low profile Allen bolts and sanded a small amount from the inward protrusion to ensure a good clearance, I've had it running and there are no witness marks that indicate any chafing.
I have a bee in my bonnet about the flex plate, when I measured up I came out with almost identical data to that listed i.e. with converter fitted 14mm from converter bolt lug to bell housing. I did my city & guilds back in the 70's and at the time remember changing cracked flex plates (on XJ6's I think), having seen this I thoroughly checked mine with a magnifying glass for cracks but couldn't see any. I am wondering if the flex plate is weak and flexing too much, if that makes sense?
I think the thing to do is go back to basics, be methodical, pull the box again and recheck everything, although I am going to source another flex plate. Has anyone experienced any problems with flex plates?

Steve

[DJT]

Hi Steve,

Like others, I did my own conversion back in 2014. I too had problems with chafing, but I cannot remember how I resolved it. I am sure it was a matter of checking the clearances and adjusting. The first box and converter I bought came from a scrap XJ40, but was faulty in that I made horrible noises when reversing. I bought another, also from a scrap XJ40 and that has been fine.

I recently had the engine out and, whilst doing so, replaced the flex plate with one sourced from Tony White. The original (from my BW35) had a worn starter ring. It also had several small (balancing?) holes in various places. The one from Tony was solid.

I will try and post some photos later.

[022Dave]

The first box and converter I bought came from a scrap XJ40, but was faulty in that I made horrible noises when reversing.

Hope you are feeling better now

[Seaking]

Have a search on Google for tourque convertor tcs look for pdf file down load scroll down to zf4hp22 section all info for sizes ect are on there.

Cheers Glenn

[BartStag]

Many thanks Dave & Glen for your help. I will take a look.

Enjoy the Bank Holiday