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Diffs, FAQ

Discussion in 'V6 Development And Modification' started by immortality, Apr 2, 2008.

  1. mrsvr88

    mrsvr88 New Member

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    getting my diff reconditioned and I'm curious if I need to wear it in afterwards?? I need to go on a 12hr drive a few days after getting it done, is it safe to drive it a long distance straight after?
     
  2. immortality

    immortality No more smoky bacon :( Staff Member

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    Best to talk to the person who is doing the rebuild. It should be fine however, the last time I had a diff rebuilt the instructions where to do 2 turns at full lock each way (to work oil into the LSD cones) and then let rip, these instructions were followed closely :driving:

    For those kiwi's that are familiar with the driveway at Steelie gears, most cars depart there leaving twin black stripes up the steep driveway with the tail swinging :D
     
    Last edited: Jun 14, 2015
  3. mrsvr88

    mrsvr88 New Member

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    Thanks mate I'll talk to my mechanic
     
  4. ITOONS

    ITOONS Member

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    Hi can someone please confirm that the VYII V6 Calais has a BW80 diff? I think I am reading the OP right but would like to have that confirmed

    cheers guys
     
  5. _R_J_K_

    _R_J_K_ Well-Known Member

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    VT s2 BW 80, 3.07:1 (auto) 3.46:1 (manual) LS1 and L67 models, V6 models continued with the BW 78
     
  6. immortality

    immortality No more smoky bacon :( Staff Member

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    Probably best to climb under the car and double check the label on the side off the diff as Holden started to make a fair few changes in the later model cars.
     
  7. ITOONS

    ITOONS Member

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    No help whatsoever. If you know the answer why don't you just say it? The sentence you bolded is the very sentence that confused me as it directly contradicts the sentence a few lines above it:
    I just wanted someone to say "Yeah, all models from VTII onwards had bw80" or "No, the v6 models still have the bw78". Not bolding a sentence I've already read.

    Thanks mate, I will.
     
  8. _R_J_K_

    _R_J_K_ Well-Known Member

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    Calm down mate, It was just easier for me to copy/paste rather than write again at the time. Not everbody is out to attack you, remember that next time before you have a whinge. If you think it's conflicting info, ask again if you didn't like my response. Apologies it wasn't to your standard.

    If you're looking to replace with a complete housing, the entire M80 housing bolts in.
     
  9. ITOONS

    ITOONS Member

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    I could say the same to you mate, I was only pointing out why your answer wasn't helpful to me. At no point did I think you were attacking me lol. Anyway, sorry if I offended you and thanks for the clarification.
     
  10. markovr

    markovr Well-Known Member

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    So no chance a vx lsd centre will go into a m78 vl housing. From looking at both centres side by side they are very similar in dimensions except for the boltup face of the crownwheel.
    It looks somewhere near 3/16 difference between housing crownwheel positions. No one has tried to add a spacer behind the crown wheel to put it into the right position or is there some other housing conflict?
    [​IMG]
    [​IMG]
     
    Last edited: Jan 3, 2016
  11. immortality

    immortality No more smoky bacon :( Staff Member

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    I wouldn't think so, with the larger gear diameter it needs to be spaced out further to get the correct gear mesh.

    Nothing wrong with the smaller M78 anyway. Plenty of big HP cars using them. The only down side is the cost of after market centres is higher :(
     
  12. Jaba

    Jaba New Member

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    Hey guys, wondering if you could help me out with a bit of a problem here.

    Currently in the process of fitting a set of VS control arms into my VZ Senator. I've swapped the handbrake mechanisms from a VZ to the VS arms.

    Everythings ready to go, the only problem is the VS driveshafts are too short and the VZ ones are too long. I figured the rear subframes from both VS + VZ were the same, therefore changing to VS arms should mean VS driveshafts would be the correct length.

    The only thing I can think of is if the VZ diff is narrower than the VS unit? Anyone able to shed some light?
     
  13. immortality

    immortality No more smoky bacon :( Staff Member

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    Can I ask why the change (are you looking to alter the wheel track width possibly or rear chamber)?

    Not sure on your predicament TBH. VZ would have a wider wheel track than the VS. Maybe you need to compare the VS and VZ arms side by side and see where the difference may possibly be.

    By the VZ model there had been a number of revisions of the IRS system, I wouldn't think that using the VS arms in the VZ subframe would be a good idea.

    I've not measured the width of a BW78 and BW80 unit but I wouldn't be surprised if the later unit is wider. People have however fitted BW80 diffs in early model Commodores so it must be possible.

    How much to short are the shafts? You are aware that the C.V. do have a little lateral movement in them?
     
  14. Jaba

    Jaba New Member

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    Looking to alter the rear track, to allow for wider wheels / tyres at a more commonly available BMW offset. I also have large 6/4 brake setup limiting my wheel choice due to clearance, something with a high offset to fit a 275/285 isn't possible.

    The only difference I can see is the cast section where the hub / handbrake setup / shock mounting point etc is. The rest of the arms look near identical.

    The VS shafts are now a good 15-20mm too short, I can only just get the bolts to thread, with a large gap between the end of the shaft and the axle hat.
     
  15. immortality

    immortality No more smoky bacon :( Staff Member

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    Fairly sure from VT onward the subframe is wider.

    Also fairly sure by VZ the angle of one of the mounting points as well the matching arm mount are at lightly different angles to improve the wheel camber during the full range of travel so the VS arm probably won't be a good match.

    VP to VR/VS had a different offset but used the same arm, the difference in track came from the different hubs used in the arms. It may be better to try and source a couple of VP hubs to achieve a narrower wheel track.
     
  16. HQH

    HQH New Member

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    Does anyone know if the 7.5" Detroit Truetrac Centre 28 spline (part #912A317) will fit into a VK borg warner (m78) housing? A lot cheaper than a Harrop
     
  17. teocali76

    teocali76 New Member

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    3.45 0575 gears in a VS IRS diff?

    Can 3.45 0575 gears fit into a VS IRS diff centre? I cant seem to find the information I appreciate anyone if you can tell me thanks
     
  18. immortality

    immortality No more smoky bacon :( Staff Member

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    No idea TBH but most likely not.

    Yes.
     
  19. Deuce

    Deuce Super Stock

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    I agree with immortality. I think I read once of someone bringing in the usa truetracks and MODIFYING them to work with the commodore diffs.
     
  20. Sandman

    Sandman Challenge Accepted

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    I was always of the under the impression thats what the Harrops were.
     

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