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Technical DEEPER DISH WHEELS versus AXLE BEARINGS.

Discussion in 'The Hokey Ass Message Board' started by twenty8, Jul 15, 2021.

  1. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    [​IMG]

    Low backspace wheels at the rear give a deep dish and a great look, especially when they have some width to them. The question I have is, are there any limits we should be aware of with regards to possible problems. Will extra deep dish wheels place too much load on the bearings and lead to premature failure, and could this be a possible safety issue.

    I am planning to use 15 x 10 inch wheels on the rear of a build, and would like to use as little backspace as reasonably possible. Rear end can be narrowed to suit.

    Thoughts ??????

    [​IMG]
     
    Last edited: Jul 15, 2021
    wicarnut likes this.
  2. spanners
    Joined: Feb 24, 2009
    Posts: 2,073

    spanners
    Member

    Entirely up to you but to me wheels that are too 'deep' look like they are about to come adrift. A 10" looks good with a neutral backspace with the tyre doing the talking. Too deep a dish sometimes looks like a garbage can attached to the axle. 8" on that rod would be as wide as I'd go but ''that's just my opinion". On a lightweight rod, bearing strain probably wouldn't be an issue like on a full body custom.
     
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  3. Mike VV
    Joined: Sep 28, 2010
    Posts: 3,029

    Mike VV
    Member
    from SoCal

    As long as the wheel center and the rim are of good quality and thickness material, you "should"...be ok.

    Now, back in the early 1970's my Dad put a set of "chrome reversed" wheels on my Moms 62 Impala. Well...knowing my Dad, he bought wheels that he could afford, meaning, that they were most likely NOT of the best quality.
    That said, when you looked at the wheels/tires from the front or rear...all four had a good bit of negative camber ! While on the car, there was no problem, cracking, breaking, wise, but also as I recall, they weren't on the car very long before a set if US, aluminum slotted wheels went on the car and the chrome wheels disappeared !

    So...there you go, both side of the issue.
    If your deep wheels show NO indication of having negative camber (it's easy to measure !) from being bent from the weight of the car, you should be safe enough.

    Mike
     
  4. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    Thanks @spanners and @Mike VV .
    After some further research I tend to agree that too much dish starts to look a bit odd. It also does put extra stresses on the axle bearings, and may lead to more frequent replacement. I guess it is a better option to determine the required rear end width to make it all work with more mainstream wheel offsets. And perhaps you are right, 8" is probably enough................:):):)
     
    Last edited: Jul 16, 2021

  5. You may find there are allowable limits to offset when it comes to registering a modified car. Each state is different, but I have build guidelines from two and they both address the subject of wheel offset.
    There have been bearing/axle failures from severe offsets and spacers in the past.
    Your state TAC rep should be able to answer questions. (I have no idea of what you are building or what rego method you are using so just giving a general heads up)
     
  6. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    Thanks @X38
    This is all I can find, and bearing tolerances is only eluded to in 7.4.3.
    This is from the Street Rod Manual.............as I am sure you know....;)
    I have not started the build yet. Just organising the build plan/application for ASRF.

    7.4 TRACK

    7.4.1 Axles may be widened or narrowed providing the change in track remains within the dimensions specified in Clause 7.4.3 and 7.4.4. The track following the axle modifications is called the revised track. The revised track may be determined by either of the two following methods. (a) Where the original track dimensions of the vehicle are known, add or subtract the amount the axle has been modified from the original track dimension to calculate the revised track, or (b) Where the either the original track dimension is not known, or by how much the length of the axle has been modified is not known, fit the original manufacturer’s wheels to the modified unit and measure the track. This measurement is the revised track.

    7.4.2 A differential may be shortened for the purposes of enabling the tyres to fit inside the Street Rod mudguards. Differentials that have been narrowed for the purpose of accommodating rims wider than 10” must not be used.

    7.4.3 Suspension unit or axle track measurements may be increased or decreased from the original manufacturer’s specified track, or the revised track as determined in Clause 7.4.1, by up to 50mm provided the alteration is within the design tolerances of the bearings.

    7.4.4 The difference between front and rear track must not exceed 75mm.
     
  7. Reidy
    Joined: May 13, 2016
    Posts: 221

    Reidy
    Member

    Try this, you may need to cut and paste into google

    Section LS - Suspension & Steering - Transport and Main Roads
    https://www.tmr.qld.gov.au › Safety › NCOP

    4.2.9 Passenger Car Wheel Track The wheel track of passenger cars (or derivatives) must not be increased by more than 25mm beyond the maximum specified by the vehicle manufacturer for the particular model. This means that the rim offset must not be changed by more than 12.5mm. Reduction in wheel track must not be performed without approval of the relevant Registration Authority. On vehicles with diagonally split brake systems, the front wheel offset (and front wheel track) should remain as original, except where the original manufacturer specifies differently with optional rims for a particular model.


    4.2.11 Off-Road and Goods Vehicle Wheel Track The wheel track of off-road four wheel drive vehicles and goods vehicles (MC, NA, NB ADR category) must not be increased by more than 50mm beyond the maximum specified by the vehicle manufacturer for the particular model. If a solid axle from another manufacturer is used, the wheel track may be increased by 50mm beyond the maximum specified by the vehicle manufacturer for that particular axle, provided all other requirements such as clearances and the tyres do not protruding outside of the vehicle bodywork. Note: This clause does not apply to passenger vehicles that are four wheel drive or all wheel drive and certified as MA ADR category.
     
  8. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    So, that would mean that the track width can only be increased by 25mm over the standard track width of the donor axle used for the project ??? That makes rear axle width and choice very important, as I said in post #4.
     
  9. IN New South Wales (Australia) you can go to any width or offset if you're prepared to go down the Individually Constructed Vehicle route.

    Otherwise getting anything over 8"wide is near impossible.

    I run 10"on two of my ICV's
     
  10. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    @Zuffen ,

    Street Rod Manual
    Section 7—Rims and Tyres PDF: 88 KB


    7.1 RIMS

    7.1.1 Double-sided safety rims must be used on Street Rods intended for road use.
    7.1.2 Wheel rims must be not less than 5” wide.
    7.1.3 Wheel rims must not be more than 10” wide.
    7.1.4 Modifications to wheel rims must only be carried out by a competent person.
    7.1.5 Steel wheels shall not be widened by having inserts welded.
    7.1.6 Slotted stud type multi-fit wheels must not be used.
    7.1.7 The front wheel rim width must be at least 60% of the width of the rear wheel rim. For 5” front rims the maximum rear rim width is therefore 8”, and if 9” or 10” rear rims are to be fitted, the front rim width must be at least 6”.
     
  11. Reidy
    Joined: May 13, 2016
    Posts: 221

    Reidy
    Member

    My understanding is the regulations I supplied are what you can do without an engineer having to sign of on the modification. The moment you start to widen or narrow a diff you are getting into certification territory.

    By carefully choosing a diff you may be able to get one that suits your needs. A lot of older differentials ran deeper dish wheels.

    The attached website gives the maximum allowable track for a large number of cars. It is a South Australian document so the regulations wont be relevant but the details are. https://www.sa.gov.au/topics/drivin...-standards-and-modifications/wheels-and-tyres

    Once you work out what track you want it is a case of looking at diffs that will give the track width and come with the deepest dish.

    Steve
     
  12. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    Am I missing something here? Is the 'Street Rod Manual' not relevent any more?
     
  13. Maybe I should have put "okay."
    I haven't memorised the manuals so am assuming what you posted is all there is. I could go and dig them out, but I'm taking your word for it.;)
     
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  14. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    Thanks Steve.
     
  15. Reidy
    Joined: May 13, 2016
    Posts: 221

    Reidy
    Member

    Again this is my take, someone may have a more educated response. When building a Street rod it must be signed of by an authorised examiner. Therefor the Street Rod Manual is guidance. You can argue all you want but if your examiner will not sign of you either have to find someone who will or do something different. I have been involved in aircraft engineering which is totally different in a lot of ways but shares one important principle. That is you have to prove how you can justify your decision.

    In this case if you are following a recognized standard it is easy to justify with no risk to the examiner. If you choose to go your own path you or your examiner will have to find a way to justify their decision that the modification is safe.
    An experienced examiner may have been down this road before and has evidence on file. If you want something that has not been done before, be prepared to pay someone who can do the engineering calculations to prove it is a safe modification.

    The short version is to first work out who is going to examine your modification. Ask them what they will accept.
    Work with them to achieve an outcome you are both happy with.

    Steve
     
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  16. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    Oh........OK. What I posted is copied and pasted directly from the Street Rod Manual - National Guidlines for the Construction and Modification of Street Rods in Australia, Second Edition. Link below........
    https://www.infrastructure.gov.au/vehicles/vehicle_regulation/bulletin/street_rod.aspx
    Not questioning anyone, especially you X38. I have an idea of your history here. Just trying to clarify if this is correct...:)
     
  17. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    The build idea I have is all relatively straight forward, and should not give any TAC examiners much reason for concern. Simple, basic construction. The only thing that may be out there is that I would like to fabricate my own body, either early woodie or early panel delivery style.

    Anyway, we may wear out our welcome with all this Aussie talk. My initial problem with wheel backspacing has been solved. A picture I saw let the imagination go a bit wild. Like has been said, we down here need to keep it relatively simple...;)
     
    Last edited: Jul 16, 2021
  18. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    @Reidy , how is the truck coming along? I saw a pic of it on a tilt tray from my neck of the woods (your avatar). Where exactly did it come from?
     
  19. Reidy
    Joined: May 13, 2016
    Posts: 221

    Reidy
    Member

    I am sure if we outstay our welcome we will find out. In the earlier standard I quoted it stated 25mm track increase for passenger cars and 50mm for commercial. The street rod manual states a maximum of 50mm if bearing design allows. So if we look at a ford 9 inch diff. This was used in some falcons as well as F100's. As the F100 is a commercial it is allowed 50mm. I am guessing whoever wrote the guidelines were pretty smart and attempted to provide a lot of flexibility.

    In your case if you were to use a diff from a commercial vehicle, maybe F100 and found a model that had a lot of negative offset from the factory you can get a very deep dish.

    Steve
     
  20. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    Hilux..........:D
     
  21. Reidy
    Joined: May 13, 2016
    Posts: 221

    Reidy
    Member

    The truck is making progress. It came from west of Warwick on our family farm. The long version is here https://www.jalopyjournal.com/forum...ruck-41-chev-long-read.1195381/#post-13606588

    I have a 115" 1942 chassis to put it on. I am putting a 261 in it which I have. For the diff I am using a BT50. For the front I am using an early international truck I beam with 6 stud hubs to match the rear. The international trucks had 12" X 2" drums but 5 stud. As it turns out I can get caravan drums in 12" X 2" with a 6 stud pattern.

    Steve
     
  22. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    Yep, thought that was Mark's tilt tray. How far out of Warwick?
     
  23. Reidy
    Joined: May 13, 2016
    Posts: 221

    Reidy
    Member

  24. WB69
    Joined: Dec 7, 2008
    Posts: 1,958

    WB69
    Member
    from Kansas

    I know I'm not in the discussion, but just wanted to say that is a great looking car!
     
  25. Elcohaulic
    Joined: Dec 27, 2017
    Posts: 2,212

    Elcohaulic

    Deep dish wheels only look good on full fender cars like from 49 up..

    Dyno Don had the best looking wheels on his 62.. You get to narrow the rear end too.


    dyno don deep dish.jpg
     
    loudbang likes this.
  26. My memory is not perfect, but I looked up my Queensland TAC guidelines and this is from the section on wheels.
    6.1.9 is the relevant part. That says to me anymore offset than 25mm from what the OEM wheel was needs full floating hubs. I take any of this with a grain of salt as the inspectors take on board build quality, sound engineering etc. when assessing what they see. If you think you might be colouring outside the lines, it doesn't hurt to ask first. The TAC people are reasonable, but are also aware that the transport dept. could potentially close down the game if people don't play by the rules that have been agreed to.

    And just so everyone is aware, the TAC is an arm of the Australian Street Rod Federation, not government. But the guidelines have been agreed to by the government.
    IMG_2705[1].JPG
     
  27. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    Thanks @X38 . Much appreciated. Trying to get organised to put in a proposal to build and want all my ducks in a row.
     
  28. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 9,214

    mgtstumpy
    Member

    TMR (Q'ld) hasn't adopted the national guidelines so the ASRF guidelines (LH9/10) apply. You also need to factor in track width during construction
     
  29. twenty8
    Joined: Apr 8, 2021
    Posts: 2,318

    twenty8
    Member

    Thanks mgtstumpy.
    So regarding rear track width, would the starting point before any changes be the standard track width for the donor vehicle that the diff was sourced from?
     

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