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Wheel offset hassles


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#26 mugginz

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Posted 15 September 2017 - 05:18 PM

After all that you may then want to widen the front track by the same amount to keep the front to rear ratio the same? SL/R track measurements had the front 0.9" wider than the rear; L34 specs had the front 1.1" wider than the rear.
 
But if you take the L34 front track, add 1" and apply it to an SL/R front end, you're gonna end up with a massive scrub radius. That would also affect the handling, perhaps more noticeably than having a lesser front track compared to the rear?

I want to run the same offset front and rear.

I whipped off the front passenger wheel this arvo and measured. So the front standard track with 255s hanging off them is fine as far as filling flares go with a +6 offset. Cause the rear track is smaller this is where the trouble is starting :)

#27 mugginz

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Posted 15 September 2017 - 05:27 PM

So to achieve your goal you should need a 10" rim (which actually measures 11") with a 5" backspace?

255s seem to look best to me on a 9 1/2" so that's what I'd like to run.

that's a long way outside the 1" allowance if a copper refuses to accept the L34 figures on the side of the road!

Unfortunately any non-stock wheels are subject to the unreasonable copper knocking them. Some will stare at a completely legal mod and still happily fill out paperwork.

At this stage I'm thinking the flares might be a no-go for a car equipped with legal rubber and wheels/offset. Fine at the front, a bit dorky at the rear.

#28 mugginz

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Posted 15 September 2017 - 06:04 PM

At this stage my problem is max legal rubber on rims appropriate for that rubber (max 10") and +6mm offset on standard rear measurements is probably no go. Fine on the front, dorky on the rear.


It's been noted here and there that the A9X ran -6mm offset wheels. This could help explain the L34/A9X front track anomaly. If Holden deemed -6mm as OK, then so would I (though I don't think it'd necessarily be OK to push that out another 25mm without further investigation.) Problem is that there's some doubt as to the -6mm figure.


This is where access to a real car would be handy. If the A9X's front BUFs are the same as the L34's, and the Cams amendment 21/12E as quoted by The Baron is accurate, we can probably assume Holden deemed negative offsets as safe.

If the A9X's front BUFs are actually wider than L34 due to bearing mounts sitting out further than L34, then the extra listed track width for A9X wouldn't necessarily be due to offset differences.


The reasons that A9X track width is listed as different are important. If it's just due to negative offsets then I think it'd be reasonable to use those offsets on other Toranas as HQ bearings are the same as Torana ones. If HQ bearings can support say -6mm offset, so can Torana ones.

#29 rexy

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Posted 15 September 2017 - 10:21 PM

Dude, you are way overthinking this.
Just fit what you want that you think looks good and get out driving the thing...
Thousands of torries have had big wheels and tyres shoved under them without falling to bits.

As long as you behave yourself on the roads the coppers will leave you alone.

#30 mugginz

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Posted 15 September 2017 - 10:26 PM

When you're looking at spending 3 grand on a set of wheels is be nice to get a set that's legal. If one cops having a bad day and puts you off the road because of your wheels, everytime he sees your car again he'll probably do the same.

But it's also be nice to get to the bottom of this because it's an issue that affects anyone that wants to fit a set of flares to a non L34 or A9X

Edited by mugginz, 15 September 2017 - 10:27 PM.


#31 hotlx8

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Posted 16 September 2017 - 07:41 AM

Here's how my car looks with 17x8 and 225 tyres and 17x10 with 255 tyres

Nice looking car LS1 74. Looks familiar!! I've got 215/40 on 17x8 the front and 275/40 on 17x10 on the rear, but the 215s are just a bit narrow for the 8" rims. Are your fronts 225/40 or 225/45, as I couldn't find the first option anywhere!

f2229a435bad4f20fbc86ab0cec839f9.jpg

f5a79677c06af4c69e687d6b46b01737.jpg


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Edited by hotlx8, 16 September 2017 - 07:42 AM.


#32 dron

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Posted 17 September 2017 - 08:04 AM

In sa there is a list of track size post 1970 from the Ezyreg sight Here http://www.sa.gov.au...k-list-2.15.pdf

 

That is the information the local inspectors will use(I hope) I am about to go down to the workshop and test fit  my little 14x7 wheels, 225-60 front tires and hq disk brake on tory drum stubs and find out if it all works on my uc. By the way the regency inspection center told me I can use a9x specks for this build.



#33 Bigfella237

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Posted 17 September 2017 - 08:15 AM

Just to save everybody searching that document, this is all the information related to a Torana...

 

SA_Track_Specs.jpg



#34 Bigfella237

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Posted 17 September 2017 - 08:23 AM

P.S. Those figures are all over the place, and they seem VERY generous.

 

But the heading does say "MAXIMUM TRACK" so do we assume these figures have already had the 1" allowance added?

 

That's the only way they even come close to what I have?



#35 StephenSLR

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Posted 17 September 2017 - 08:28 AM

But the heading does say "MAXIMUM TRACK" so do we assume these figures have already had the 1" allowance added?

 

My guess is 'Maximum' covers the cars that came out with thinner rims. i.e. the LX figure would be the SL/R track width, the SL was smaller, etc.

 

s



#36 Bigfella237

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Posted 17 September 2017 - 08:40 AM

Looking closer at the LH L34 figures, which had only one sized wheel as an option, the GMH Service Bulletin says;

Front: 57.89" (1470.4mm)

Rear:  56.82" (1443.2mm)

 

If I add 25.4mm (1") to the GMH specs we get:

Front: 1495.8 (rounded up to 1496)

Rear:  1468.6 (rounded up to 1469)

 

Their figures are:

Front: 1496mm

Rear:  1469mm

 

So I can only assume they've already added the 1" allowance to all those figures?



#37 Bigfella237

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Posted 17 September 2017 - 08:43 AM

DOH!

 

I should've just read the first page of the PDF...

 

The vehicle details in this Fact Sheet specify the maximum allowable wheel track for each vehicle including the 26mm tolerance allowed under the Regulations.



#38 dron

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Posted 17 September 2017 - 04:58 PM

   Just to complete my last post. UC style front calipers with the hz (I think) pad retainer will not bolt up to the CRS drum to disk adapter plate.

 

     They would fit if the plate had the caliper mounting holes 4 to 5mm lower rotating the caliper slightly lower to the front. With the mount as is the caliper hits the top of the stub and only 1 bolt will fit. The caliper will clear everything lock to lock at full suspension travel using the uc upper arm.

 

       I have a set of WB front calipers that will bolt up to the adapters so I will try to fit them next. It was necessary to use the Left caliper ( alloy part) on the Right side with the RH (cast part) mounting bracket to get the bleeder to the top where it needs to be. I suspect that I would need to grind off metal to clear the steering arm, I will not use them if that is the case. 

 

  From what I have worked out so far I think the best way would be to have 2 plates made locally with a slightly different mounting position for the caliper but then it would not be an off the shelf part and I could not tell the inspector it is a CRS part. May then need an engineer and all the extra cost.

 

 



#39 mugginz

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Posted 17 September 2017 - 08:08 PM

Got some more figures just to confuse things more. My understanding of the standard 4.5" rim was it had a +19 offset and the 5.5 had a +32, which would mean the 4.5" equipped cars had a wider track than the 5.5" ones, but not according to the figures from this book.
 

 

LHManualCover.jpg

 

LHManualTracks.jpg






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