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Unbearable Arch Rub!

Discuss problems you have had or are having with your Z4
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bmwaddict
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Unbearable Arch Rub!

Post by bmwaddict » Thu Feb 09, 2017 7:39 pm

Currently zedless :(

'07 Mugello Blue Audi B7 RS4 Saloon with added goodies
'94 Black/Silver/Green Honda CBR400RR
Previous:
'07 Ruby Black Z4MC
'07 Sapphire Black Z4C 3.0si Sport

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tominator
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Unbearable Arch Rub!

Post by tominator » Thu Feb 09, 2017 7:46 pm

idej_jedi wrote:
Dav the wheel nut wrote:What is the offset of your wheels? It could be the most significant point in all this and yet no one has mentioned it :o
Not sure what my offset is (or how to check it). From the sounds of things this could be the problem. Any ideas what they should be?
Are your wheels the Riva DTM'S? If so the offsets are fronts 34, rears 37 :D

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mr wilks
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Unbearable Arch Rub!

Post by mr wilks » Thu Feb 09, 2017 7:57 pm

bmwaddict wrote:
idej_jedi wrote:
Z4M-2006 wrote:I had 235's on the front and lowered on Eibachs with no issues..

I dare say the wheels are the incorrect offset..
Thanks for this...how do I get the offset changed?
You can't, offset is how close the mating face of the wheel is in relation to the front/back of the wheel. All alloys have an offset, usually stamped into the back of the spokes.
Not strictly true as a higher offset can be made lower with spacers , a lower offset however is far trickier to deal with although machining off the rear is not impossible , Machinemonkey has done this i believe :?
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Buckz
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Unbearable Arch Rub!

Post by Buckz » Thu Feb 09, 2017 7:59 pm

What wheels have you got?
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Unbearable Arch Rub!

Post by tominator » Thu Feb 09, 2017 8:10 pm

Buckz wrote:What wheels have you got?
What set up do you have Buckz, are they 19" on your coupe, what offsets are they, is it lowered, and what size tyres?
I'd like to lower my coupe, and fit 19" cls's without rubbing issues!!

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Unbearable Arch Rub!

Post by bmwaddict » Thu Feb 09, 2017 8:36 pm

mr wilks wrote:
bmwaddict wrote:
idej_jedi wrote:
Thanks for this...how do I get the offset changed?
You can't, offset is how close the mating face of the wheel is in relation to the front/back of the wheel. All alloys have an offset, usually stamped into the back of the spokes.
Not strictly true as a higher offset can be made lower with spacers , a lower offset however is far trickier to deal with although machining off the rear is not impossible , Machinemonkey has done this i believe :?
True Mr W, just explaining to the o.p. that in terms of immediate effect offset can't be changed, as in the wheels are that offset and they always will be, but as you say spacers have the effect of altering offset, as can machining the wheels.
Currently zedless :(

'07 Mugello Blue Audi B7 RS4 Saloon with added goodies
'94 Black/Silver/Green Honda CBR400RR
Previous:
'07 Ruby Black Z4MC
'07 Sapphire Black Z4C 3.0si Sport

Dav the wheel nut
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Unbearable Arch Rub!

Post by Dav the wheel nut » Thu Feb 09, 2017 8:40 pm

idej_jedi wrote:
Dav the wheel nut wrote:What is the offset of your wheels? It could be the most significant point in all this and yet no one has mentioned it :o
Not sure what my offset is (or how to check it). From the sounds of things this could be the problem. Any ideas what they should be?
The offset, as someone has mentioned, is stamped on the inside of the wheel rim. It is shown as an et number. For example it will be stamped as et35 or et38. If you find this number and give the width of the wheels eg. 8 inch or 8.5 inch wide, it will be a starting point to try and sort it.
I run 8.5'' on the front, offset et35, lowered on eibachs without any issues.
I always say to people you are playing with very small margins when you change wheel sizes and one or two millimetres can make all the difference

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Unbearable Arch Rub!

Post by Raj_UK » Thu Feb 09, 2017 8:41 pm

I machined wheels once upon a time to increase offset by a few mm. Was a major fail :o I didn't take into account after machining the part of the wheel mating to the hub would be wider and it was fouling against the brake caliper!!
Z4less :?

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Unbearable Arch Rub!

Post by idej_z4 » Thu Feb 09, 2017 9:38 pm

Buckz wrote:What wheels have you got?
Riva DTMs

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Unbearable Arch Rub!

Post by idej_z4 » Thu Feb 09, 2017 9:42 pm

Thanks for this!!! Reading it sounds like my offset is too high as I'm getting arch rub. It also sounds like I can fix it with spacers. Just need to work out what size to get. :)

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Unbearable Arch Rub!

Post by idej_z4 » Thu Feb 09, 2017 9:48 pm

Dav the wheel nut wrote:
idej_jedi wrote:
Dav the wheel nut wrote:What is the offset of your wheels? It could be the most significant point in all this and yet no one has mentioned it :o
Not sure what my offset is (or how to check it). From the sounds of things this could be the problem. Any ideas what they should be?
The offset, as someone has mentioned, is stamped on the inside of the wheel rim. It is shown as an et number. For example it will be stamped as et35 or et38. If you find this number and give the width of the wheels eg. 8 inch or 8.5 inch wide, it will be a starting point to try and sort it.
I run 8.5'' on the front, offset et35, lowered on eibachs without any issues.
I always say to people you are playing with very small margins when you change wheel sizes and one or two millimetres can make all the difference
I'm running 8 inch at et34 on the front - as you've got 8.5 could the answer be to get some 5mm spacers??? Cheers.

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Unbearable Arch Rub!

Post by jamie_z4 » Thu Feb 09, 2017 9:52 pm

You won't fix it with spacers mate it will make the problem even worse It will make the wheels more prominent which will rub the Arches more. Only resolution is wheels with a higher offset or raising suspension
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Unbearable Arch Rub!

Post by idej_z4 » Thu Feb 09, 2017 9:53 pm

jamie_z4 wrote:You won't fix it with spacers mate it will make the problem even worse It will make the wheels more prominent which will rub the Arches more. Only resolution is wheels with a higher offset or raising suspension
Gutting! The article that I just read said that if the offset was too high it could be fixed with spacers. :(

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Unbearable Arch Rub!

Post by jamie_z4 » Thu Feb 09, 2017 9:55 pm

The problem is your offset is too low. The lower the offset the further out from the hub the wheel is
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Current: 2.5i Titan silver

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Unbearable Arch Rub!

Post by Ducklakeview » Thu Feb 09, 2017 9:57 pm

Just a point..

You haven't got staggered wheels have you, ie different offsets front and rear? If so, is it possible you have a rear wheel on the front, or vice versa??

Mike
Last edited by Ducklakeview on Thu Feb 09, 2017 9:57 pm, edited 1 time in total.

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