Wheel drilling

  1. Wightsparks

    Wightsparks Forum Supporter

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    Engineering input please!

    Upgrading the rear suspension of my Sandrail to IRS using the back end off a Porsche 944 S2 Turbo.

    This leaves me with a problem in that the Porsche wheel studs are 5 x 130 PCD

    2017-09-26 18.13.12.jpg


    and the steel wheels with my big mud tyres on are 4 x 130.

    2017-09-26 18.12.58.jpg


    I have looked at lots of options - I don't want to mess with the Porsche studs and disc, converters are non existent and it seems no one is keen on selling just two 15" Porsche wheels from the 1980's.

    My plan that I would like some input on is to drill and then re-enforce the existing wheels.

    First I would have a template made (CNC/waterjet cut) with a combined 4x130 pattern M14 holes (for bolting to the wheel) and 5x 130 pattern with M5 holes for pilot drilling (one would be shared).

    Then I was thinking that as the wheel would then have a few extra holes in it and the centre hole is too big for the Porsche centre, I can buy readily available 5mm steel, hub centric spacers to use as backing plates and sandwich the wheel in between.

    Any reason this wont work?

    Do you think I need the backing plates/spacers?

    Better ideas?

    Anyone make me a template (for beer tokens of course!)
     
  2. gordon stephenson

    gordon stephenson Forum Supporter

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    Cant you cut the centre out of the wheel and weld in another that suits the studs?
     
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  3. octo0072000

    octo0072000 Member

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    remember the wheel rim is located on the 3 tabs on the hub this takes the load not the bolts/studs
     
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  4. pod70 Member

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    Location:
    Kent, England
    I'm fairly sure that fitting the Porsche hubs & brakes was quite a common upgrade for beetles so I'm guessing that the beetle hubs will fit the 944 suspension arms.
    This does mean that you end up with drums but from memory there are plenty of rear disk conversion kits available for aircooled VWs. Might be a bit more expensive but certainly easier and you could re-coup some of the money selling off the 944 bits. Been a while since I messed with old VW's so I could be wrong.
     
  5. colnerov

    colnerov Member

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    Nr Gatwick UK
    Hi, More or less, the three lugs are the spigot to centralise the wheel. The studs and nuts supply the clamping force and the driving load is taken by the friction between the wheel and hub face.

    Colin
     
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  6. Wightsparks

    Wightsparks Forum Supporter

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    I can't do that with the sort of accuracy needed.

    Good point - the Hub centric spacers (71.6mm for some strange reason) that I plan to add will locate on the 3 tabs and spread the load out - So that answers one question - yes I need those plates
     
  7. gordon stephenson

    gordon stephenson Forum Supporter

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    Skelton in Cleveland U.K.
    There are several ways of maintaining accuracy.Weld in new plates then have them drilled and centre hole machined by CNC etc. What sort of accuracy are you needing with big mud tyres?
     
  8. Wightsparks

    Wightsparks Forum Supporter

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    Sorry I meant with my machinery (and skills!) - any external CNC will require tyre removal and re-mounting.
    This way I bolt on the template to the existing wheel bolt holes (so it is centred by them), mark and drill the 4 new holes, then re-assemble with a 5mm steel backing plate that has the correct centre bore (£25 for 2 plates).
     
  9. knighty Member

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    why not drill the disk and hub instead ? then you won't lose any strength from the wheel rim

    disk and hub should be more than strong enough with a few extra holes... and you can always weld up the old holes if you want?

    you can re-use the old studs (or use new ones) they're just pulled into a countersink on the back anyway
     
  10. Wightsparks

    Wightsparks Forum Supporter

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    That is certainly an idea and I did look at this (and lots of other options!). You can't see in the pic but the hub is actually quite thin and only locally double thickness at the bolt holes. I would still need a template to drill, some of the holes would be crossing the local double thickness so would need grinding back and it would not centre the wheel. Also that means I go from 5 bolts to 4.

    I think 4 (extra) holes in the 8mm wheel plate with an extra 5mm backing plate would be stronger. I could weld the backing plate to the wheel but with it sandwiched tight by 5 wheel bolts I don't see welding it adding any strength, just the possibility of distortion.
     
  11. gaz_moose Member

    Messages:
    937
    Location:
    tamworth staffordshire
    looks like the disc sits proud of the hub face. I would just machine up a top hat spacer and press it onto your spigot on the hub.heat it up cool it down or something like that.

    draw the PCD's in autocad then print it out and glue it to your wheel then drill them out.

    do your wheels have a taper and a raised bit for the wheel nuts.
     
  12. knighty Member

    Messages:
    1,696
    Location:
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    what size are your big mud tyres ?

    is it not easier to get some new rims ?


    or... get some 4x130 spacers from ebay and re-drill them to suit the 5x130 hubs ?

    there's loads on ebay... if you pick one to match your wheels (so the center would be right) and then re-drill to suit the hub?
     
  13. Wightsparks

    Wightsparks Forum Supporter

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    Then there is no way to make that drawing central to the wheel. That's why I need the template to fit on the existing holes then pilot drill the new holes.

    Nope. As per original post! Been looking for weeks.

    But that is an excellent idea. I'll check that out. I don't want to add too much extra width as the Porsche back end is already slightly wider.
     
  14. Wightsparks

    Wightsparks Forum Supporter

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    Alas spacers not going to work as none of them have the correct centre bore (no VW wheels made with the same bore). Lots of the reverse conversion - which I knew- but strangely people wanting to put VW wheels on their 944 is not so popular, can't think why:whistle:
     
  15. knighty Member

    Messages:
    1,696
    Location:
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    will no local engineering place make you a couple ?

    I've got a mill, and I'd offer to give it a go for you... but I've never used it before - you're welcome to have a go if you're up this way at all
     
  16. gaz_moose Member

    Messages:
    937
    Location:
    tamworth staffordshire
    draw the centre bore and original PCD on the template and 'eye-line' it. I drilled out some old weller steel wheels this way, only issue was had to but the wheel nuts on backwards as the rim did not have enough 'meat' to put a taper on.

    or..

    bolt your 5 stud disc to your wheel using 1 of the wheel bolts, then knock up a spacer that fits in the centre bore to align the two. then drill out the other holes through your disc. you could knock up a bit of steel bar with the same diameter as the stud hole in the disc with a sharp point on the end then use that as a centre punch to ensure you are centred.
     
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  17. Wightsparks

    Wightsparks Forum Supporter

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    Thanks for the offer Knighty - bit far for me though! I could get them made, a great idea as an alternative if readily available but I don't think they are a better or worse solution than bolting the wheels on directly with 5 studs, and they would be much more expensive.

    Thanks Gaz - I'm going to use your idea of a paper template to make the actual template - actually I am going to make 2, and drill out the 5x130's in one of them so I can fit it and make sure it's perfect.

    Lots of useful input got a couple of extra ideas and confirmed the need for the backing plates. Thanks all.
     
  18. gaz_moose Member

    Messages:
    937
    Location:
    tamworth staffordshire
    just make sure you modify your spare wheel.

    could you not just turn up a collar and tack weld it to the centre bore of your wheel?? (assuming your wheel has a larger hole than the hub centric part of your hub) making stonking big wheel spacers out of steel don't sound very good, I had some 10mm thick ones someone else made and they were pretty weighty.
     
  19. Wightsparks

    Wightsparks Forum Supporter

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    Spare wheel ? Not on this car!
    2017-09-19 09.59.00.jpg


    There isn't a big spacer? The 4 extra holes are drilled in the wheel then a 5mm steel plate with the correct holes/PCD/center bore is added to the outside of the wheel before the nuts are added. I have just started learning Fusion 360 (having spent years on Rhino 3d) so I'll rustle up a sketch...

    http://www.ebay.co.uk/itm/PORSCHE-997-5mm-STEEL-WHEEL-SPACERS-X-2-BRAND-NEW-5x130-PCD-71-6mm-Bore/253092598754?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908131621%26meid%3Ddedadeb871604744b1b56e5a1ca16b91%26pid%3D100678%26rk%3D1%26rkt%3D5%26sd%3D253092598754&_trksid=p2481888.c100678.m3607&_trkparms=pageci%253A3808d5b6-a488-11e7-8140-74dbd18016d0%257Cparentrq%253Aca170d6415e0aa14438cf687ffff5e4e%257Ciid%253A1
     
    • s-l500.jpg
  20. addjunkie

    addjunkie Member

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    5,167
    Location:
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    Once youve fitted the 5 hole disc for re drilling can you not just tack to the wheel for strenght and weld the old holes up from the back

    A nice bead of tig around then a smoothing of filler, bit of paint....
     
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