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Thread: A 'Pumpkin Chain' proposition.....

  1. #76
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    pardon my ignorance but is there a thread that summarizes how this works?
    I am in the midst of trying to start up an insurance company (workers comp) so time and money are presently limited. Many of the upgrades, from Brembos to Eisenman exhaust, are enticing but not within my current budget. But this...if I understand correctly, seems a very inexpensive way to get the benefit of LSD. Any other parts needed? Labor estimate would also help. Lastly, I am in MI and the weather will likely keep my car in storage until late April so I would not be able to get involved until then.

  2. #77
    Administrator thegunguy's Avatar
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    This is merely a group that is sharing a blank final drive housing as a build-up medium for the purpose-made Quaife LSD in an effort to save time, not the differential itself. To participate, you must have been part of the purpose-made Quaife LSD group purchase last year. If you were not a part of this group, the thread does not apply, and you will have to source an alternative LSD solution. There are several alternatives on the market. Expect parts and labor to range from $3k to $6k.
    thegunguy

  3. #78
    Administrator thegunguy's Avatar
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    Quote Originally Posted by KenZ8 View Post
    Bavauto has a Quaife differential for the Z8 on their website for $1500, available in a week's time.(part #30.309.170)
    "This unit is a direct replacement for the factory differential. Basically remove the differential cover, remove the differential, take
    the ring gear from your existing unit and mount it onto the Quaife and then shim it as necessary for proper gear mesh. "
    Is this similar to what you are doing with the pumpkin? Thanks for helping me understand the process.
    Ken,

    As Quaife does not normally produce a LSD that is a direct-swap for the open-diff in the Z8, I doubt their claim. It certainly warrants further investigation, but the Z8 final-drive is a bit of a mis-match of parts. Many people assume that since drive-train is akin to the M5 that the same applies to the final-drive. Not so. The final drive in the Z8 is actually more like the E65 7 series, from which it derives its gearing. However, the diff and housing are specific to the Z8.

    There are companies that are fitting 5 series compatible LSDs into the Z8, but this process required milling the interior of the final-drive housing. So, this is not a direct-swap.

    About a year ago, Brett at Koala indicated that he was developing a diff to fit the Z8, but I am unaware of his progress. Metric Mechanic had also mentioned developing one.
    thegunguy

  4. #79
    Team Z8 KenZ8's Avatar
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    I think I understand...

    Are you installing your Quaiffe into the empty "pumpkin" before putting your cars up on a lift, allowing you to do a swap once the car is up rather than wait with it disassembled while the quaiffe is fitted into the pumpkin? If so, the first guy got a new housing installed into his car, the second got to keep the housing from car #1, and so on??

  5. #80
    Administrator thegunguy's Avatar
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    Exactly.

    When I did mine last summer, I purchased a spare final-drive to do the build. That way I will always have the original one in it's unmodified condition.

    The group here just did the same with one spare shared by all participants.
    thegunguy

  6. #81
    Z8 Addict Z8doc's Avatar
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    Ken....

    Quote Originally Posted by KenZ8 View Post
    Bavauto has a Quaife differential for the Z8 on their website for $1500, available in a week's time.(part #30.309.170)
    "This unit is a direct replacement for the factory differential. Basically remove the differential cover, remove the differential, take
    the ring gear from your existing unit and mount it onto the Quaife and then shim it as necessary for proper gear mesh. "
    Is this similar to what you are doing with the pumpkin? Thanks for helping me understand the process.
    Read the LSD thread carefully as it is all explained there. IF.... you were not part of the LSD group buy, too late for that. The Quaifes on that buy were made to a specialized lightweight specification and made to fit into the Z8 housing without modificaition. Unless Quaife is now selling the specialized design (US owners patented change) through BAV, it is doubtful that a Quaife they will sell you will do what they claim. More likely, the Quiafe will be a standard size Quaife, ones that are used in the e39 5 series, and then have to mill out the housing to fit it in the Z8's final drive housing (this is what Koala Motorsport first did and can still do). Metric Mechanic can do the same and should not affect the pumpkin chain.

    The other choice is that MM sell their own Variable % Salisbury type LSD, which also can be made to fit a Z8 housing. It is a clutch style and works with similar results but the clutch packs do wear out over time, which compared to the Quaife, is not as good but.... will accomplish what you want as far as traction gains. Talk to Jim (or for those who have spoke to him - he talks, you listen ! ) and he will explain your options.

    I too would recommend the Quaife AND the 3.64 gears. I like the increase in torque provided by the 3.64 gears as judged by the "seat of my pants" feeling!! I do not think you would regret the choice.

    Hope that helps!
    Best Regards,

    Jeff
    61995 Silver /// Rot - Original Owner
    Z8 Club of Germany e.V. #102

  7. #82
    Team Z8 KenZ8's Avatar
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    I can't imagine

    even more torque than I have now- it sounds like a blast!

  8. #83
    Have any of you guys noticed a feeling of there being some slack in the driveline since fitting your LSD's?

    I noticed it quite a lot on the drive back down to LA, especially when you are gently rolling on and off the gas in 3rd & 4th in the 4-6000 rpm range. I find it interupts the flow of the driving experience, and I'm not really happy about it. However I'm not sure if it is just my unit, or if it is something that is common to all the others out there too.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  9. #84
    Administrator thegunguy's Avatar
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    I don't recall anything like that. Although, mine is from an earlier lot.
    thegunguy

  10. #85
    Z8 Madness 2112's Avatar
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    almost sounds like a bad u-joint .

  11. #86
    We'll have a chance to look into that more carefully at Buttonwillow.

  12. #87
    What would cause a U joint to go bad, and is it hard to fix?
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  13. #88
    Sport Button On - DSC Off Dogsbreath's Avatar
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    Andrew - no slack here

    Ken - get the different ratios - it is impressive

    Dave P

  14. #89
    Z8 Addict Z8doc's Avatar
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    It is....

    Quote Originally Posted by KenZ8 View Post
    even more torque than I have now- it sounds like a blast!
    The torque improvements with the 3.64 vs the oem 3.38 are as follows:

    Stock 3.38 gears -- 364 lb-ft torque

    3.64 gears ---- 408 lb-ft torque (as measured when I dyno'ed my Z8 -- 5 pull average). The only other improvement I have is stage 1 Dinan software.

    That is definite "seat of the pant' improvement!! And, as we all know -- it is torque that leads to acceleration!!
    Best Regards,

    Jeff
    61995 Silver /// Rot - Original Owner
    Z8 Club of Germany e.V. #102

  15. #90
    Z8 Madness 2112's Avatar
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    Quote Originally Posted by macfly View Post
    What would cause a U joint to go bad, and is it hard to fix?
    Not hard to replace or relatively expensive. I wrecked a few on various vehicles. Usually by doing burnouts/drag racing stunts. I have outgrown most of that.

  16. #91
    Since I have babied this car I doubt its that, sadly I suspect it is something within the LSD, but since I won't be doing high miles with it I may just learn to live with it, and not worry.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  17. #92
    Z8 Addict Z8doc's Avatar
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    Hey Mac,

    I would call Jim at MM to discuss it with him -- IF.... it is "slack" within the final drive itself because the backlash of the pinion / ring gear is off and not adjusted properly, that will lead to premature failure and if that occurred, your Z8 could look like the alternative rock musicians "Smashing Pumpkins" had been driving your Z8! IF.... the "slack" is within the Quaife differential itself (which I doubt) same thing can happen!

    I would talk to Jim to see if he can instruct you on how to test / examine your Z8 to see if there is any play. This could involve removing the rear cover on the rack.

    It could be a factor of inadequate lubricant (either amount or type/weight) as PeterPan may have not adequately filled it or used the correct type/weight of gear lubricant as the high rpm may not be letting adequate lubircation when you are at speed and your "pumpkin" and gears may be overheating. The Quaife requires 75W90 fully Synthetic Gear oil. Don't forget that your new Quaife requires the same restrictions that your Z8 required when new, no greater than 4000 rpm and 100 mph for the first 1500 miles then change the gear oil, just like when it was new. Then let 'er rip

    Hope that helps -
    Best Regards,

    Jeff
    61995 Silver /// Rot - Original Owner
    Z8 Club of Germany e.V. #102

  18. #93
    I did speak to Jim, and he gave me some tests to do, but I've already forgotten what they were! I'll call him again next time I'm about to take the car out to jog my memory. I know that Peter Pan put the right oil in, as we discussed it at length, and they have installed about a dozen of the different units from Brett and our group combined.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  19. #94
    Z8 Addict Z8doc's Avatar
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    Peter Pan I am sure is competent but... human error is possible, so just to be complete, I would independently check the fluid level while you're evaluating, just to be sure, it is easy enough to do.
    Best Regards,

    Jeff
    61995 Silver /// Rot - Original Owner
    Z8 Club of Germany e.V. #102

  20. #95
    4,000 RPM for 1500 miles. That could easily be a half year.
    I'm curious, where were we supposed to get those instructions from?

  21. #96
    Z8 Addict Z8doc's Avatar
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    Ted, I posted it in the original Quaife.....

    Quote Originally Posted by The Bender View Post
    4,000 RPM for 1500 miles. That could easily be a half year.
    I'm curious, where were we supposed to get those instructions from?
    posting. I spoke with Quaife America, as well a Koala Motorsport (recommended 1,200 miles) when I was doing my original research on the subject. Since we had that same original restriction, I asked them if the same would apply to this, and they recommended it. Metric Mechanic also agreed. Rifle and I drove the heck out of ours after doing the upgrade so we would be in great shape for the MITM last summer, as we both got ours done just before that.

    As a new owner, there was a sticker between the radio head opening and the string of buttons on the console that stated "1500 mile service mandatory". When I took mine in for that, I asked my service advisor what that was for and was told, to service the rear final drive, i.e., gear lube change. Now, I know lots of racing folk as well as my experience with other differential rebuilds (my son and I have done several American 4x4 mods) and never limited it like the above -- so, could you let it rip -- probably. But, the gears/bearings/seals may mesh/seal better after a break in period so, who is right -- not sure.

    My advise, drive it daily for now to get to the 1,200 miles, change it and go.
    Best Regards,

    Jeff
    61995 Silver /// Rot - Original Owner
    Z8 Club of Germany e.V. #102

  22. #97
    Thanks, Jeff. I guess no .

  23. #98
    Sport Button On - DSC Off Z8-NL's Avatar
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    Koala Motorsport gave me smilar advice, drive easy for 1500 km (seems a difference if you drive in KM you need less) and change lubs after that. then you can give it what you got!

    Still very happy even after 2 years no regrets whatsoever

    Good luck and enjoy

    Z8-NL

  24. #99

    The pumpkin is headed back to MM

    So who ever is next let me know.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

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