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Thread: Discovery Td5 Torque Converter Options for ZF Transmissions

  1. 23rd July 2012, 08:44 PM #1
    RoverNova Guest

    Discovery Td5 Torque Converter Options for ZF Transmissions

    Hi all,

    One of the first things i noticed with my Td5 Auto Discovery was the stall speed on light throttle. The stall needs to be lower to allow better low RPM drive ability.

    I have searched this forum and have found that importing a converter from the UK is a popular option. But i cant see why the same job cant be preformed here by a local torque converter shop.

    I have set a task to find some converters and strip them down and see what what.

    Firstly I found a 1998 V8 P38 Range Rover, I then found a Td5 Discovery converter (with the help of gazk).

    First impression is the main issue with using the larger V8 converter is the bolt up pattern has 4 bolts and the diameter of the plat that to hit the ring gear is alot small than a Td5 and also protrudes further than the td5 converter.

    I then stuck the Td5 unit in a lath to cut the weld and have a look. Now i found something interesting on the main converter cover. The fins have a large angle on the outer section which is mostly seen on HI-RPM stall converters. Bending these straight would allow more oil to pass hence push the impeller with less revs.

    Ill cut the V8 one this week and have a see what it looks like. Also if anyone has photos or links to photos of the UK converters i would be interested in seeing the spigot face.

    Cheers
    Rhys
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  2. 23rd July 2012, 08:59 PM #2
    justinc's Avatar
    justinc
    justinc is offline Swaggie Vendor
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    rhys, it seemed to me that the v8 internals were very close to the uprated td5 ones, a new spigot and mounting points were added to the front face and possibly that is all? the v8's bigger lockup clutch and vane angles were the major improvements.

    jc
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  3. 23rd July 2012, 09:27 PM #3
    RoverNova Guest
    With all the threads on the converter's i thought there was no hope for the Stock Td5 unit it terms of lowering the stall. But if your where going to get your standard unit rebuilt the vanes can be straightened and you could drop the stall RPM 300 rpm (Total stab in the dark) This is common practice for the LS1 commodores but you actually bend them to gain an extra 300rpm higher stall.

    If there gearbox in the discovery was a piece of P|ss to R&R i would give it ago with just the vanes to see what difference it makes.

    Ill know more about the V8 unit once i pull it apart.
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  4. 23rd July 2012, 10:22 PM #4
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    Slunnie
    Slunnie is offline Swaggie Gold Subscriber
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    Reading the Ashcroft tranmissions website, from what I can gather one of the problems is the TD5 (small) torque converter can barely prevent slipping during lockup. So they adapt the V8 (medium) to mount to the TD5 flex plate and benefit from the larger lock up clutch and lower stall speed.

    Ashcroft Transmissions - ZF4HP22
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~
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  5. 24th July 2012, 01:39 PM #5
    Tombie Guest
    Quote Originally Posted by Slunnie View Post
    Reading the Ashcroft tranmissions website, from what I can gather one of the problems is the TD5 (small) torque converter can barely prevent slipping during lockup. So they adapt the V8 (medium) to mount to the TD5 flex plate and benefit from the larger lock up clutch and lower stall speed.

    Ashcroft Transmissions - ZF4HP22
    And it works bloody brilliantly...

    Had ours in and running for 6 months...

    VNT + Ashcroft TC = Best thing I've done to the TD5
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  6. 24th July 2012, 10:11 PM #6
    RoverNova Guest
    I still haven't cut the V8 unit as it looks like ill need to machine up an adapter plate to weld to the V8 housing to allow it to bolt to the Td5 Engine.

    The main thing i cant get my head around is the setup of the Td5 converter. It looks like some performance Hi-Stall unit ready to hit the race track.

    Ill post some images up when i have the V8 apart so you can see the difference.

    Quote Originally Posted by Slunnie View Post
    Reading the Ashcroft tranmissions website, from what I can gather one of the problems is the TD5 (small) torque converter can barely prevent slipping during lockup. So they adapt the V8 (medium) to mount to the TD5 flex plate and benefit from the larger lock up clutch and lower stall speed.

    Ashcroft Transmissions - ZF4HP22
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  7. 24th July 2012, 11:07 PM #7
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    Jason789
    Jason789 is offline Master
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    I spoke to one of the Ashcroft blokes about 15 minutes ago on the subject of these 'uprated' torque convertors.

    If you have a motor that is modified for higher HP, then the bigger torque convertor is great.
    If you have a stock motor, then stick to the stock torque convertor. I appreciated the honest reponse from the fellas(they didn't go the hard sell). I won't be needing one myself, but for the higher output motors they sound great.

    Cheers,

    Jason
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