front wheel scrub, can i have them machined?

[mxmattd]

I got 15x7 torque thrust II's all around about a year ago, and i think they may have suggested the wrong backspacing for me. the wheels scrubbed a bit, so i rolled the fender lip and did the shelby drop, which helped i great deal. i've noticed that there is a bit of room behind the wheel, and was wondering if it is possible to have the back of the wheel turned down a bit so it will sit further back in the wheel well. has anyone ever done this? or is it unsafe to take any material off the wheels?

thanks,

-matt

 

[dodgestang]

What is the backspacing you have on there now (and the size of the tire)?

 

[rbohm]

yes you can trim the mounting surface, but only enough to true the surface. there isnt enough material to change the backspacing more than about .030"

 

[zookeeper]

I've regularly milled as much as .250" off the mounting pads of various wheels with no problems. All the street wheels I've ever seen had a ton of material back there anyway. A local custom car shop has trouble measuring backspacing, so they bring the wheels to the shop I work at and I set them up in the CNC machine. I've also cut them in a lathe, but it's hard not to mark the edge of the wheels, so I have a quick program to do it. It only takes me about 15 minutes per wheel including setup. You do need to be aware that removing material off the mounting pad reduces the caliper clearance, so if it's tight now, you may also need to machine a bit off the spokes, which I've also done with no issues.

 

[mxmattd]

thanks guys. does anyone know of a machine shop in the socal area that would have the ability to do this as well as the experience to know if its safe with my wheels?

i'll measure the backspacing today and get back to you, i don't remember exactly what it was.

 

[mxmattd]

the backspacing looks to be 4.75, and the tires are 225 60R15

it looks like there is more than an inch of clearance between the spokes and the calipers.

from reading dodgestang's chart, it looks like i should have gotten 4.25 backspacing with those wheels. i wish i had seen the chart first! shame on me for trusting a wheel shop.

i'm guessing .50 is way too much to take off the wheel, any other ideas besides buying new ones?

 

[zookeeper]

Yeah, I don't think I'd try to take off 1/2", but you could try having 1/4" cut off (assuming your mounting pads are thick enough) and see if it helps. It's really a minor machining job, and that may well be enough.

 

[dodgestang]

Do you know what happens when you have a wheel with 4.75 backspacing and you mill a 1/2 inch of? You end up with a wheel that has 5.25 inch backspacing.

 

[mxmattd]

wow i'm such a noob. i was measuring from the mounting pad to the FRONT flange of the wheel. its dark and cold so i'll have to figure out the real backspacing tomorrow. i'll let you know how thick the mounting pad is too so you could give me an idea of whether or not this will work.

 

[mxmattd]

i haven't physically checked out the backspacing yet, but the invoice from the wheel place reads:

TORQ THRUST II 15X7 5-4.5 3/4 BS

does this make sense? i assume the backspacing is encoded in there somewhere?

 

[zookeeper]

It looks like it's indicating you have a 15x7 wheel (which you already knew) with a 5 lug wheel with the bolt circle of the lug holes being 4.5" which is the standard Ford pattern. As far as the 3/4 BS goes, I don't have a clue, but my best guess (it's just a guess) is this: a 7" wide wheel would have a centerline of 3.5", right? If you add 3/4" (or .75") to this, you come up with 4.25" backspace. Maybe that's what you have on the car now. Does this sound right?

 

[dodgestang]

If you purchased these of the shelf and did not get custom backspacing most of the time with American racing they are 3 3/4 back spacing. This is a popular wheel size and when paired with a 215 60 15 tire having them rub the front fender on occasion is quite common (more common I believe than many people with these wheels admit too ) However if you do have 3.75 backspacing and then, if you can mill 1/2 of you will get 4 inch of back spacing, but I don't think you will find enough material there without compromising the integrity of the wheel. Get your alignment checked and have them put in a little more tip (negative camber IIRC).

 

[mxmattd]

now that you mention it, i do remember the problem getting worse after replacing my worn out upper ball joints. maybe this affected the camber?

 

[dodgestang]

When you have a ball joint replaced, you should get an alignment.
1. Did the shop align the car
2. If 1=no then get an alignment
3. If 1=yes then what specs did they use (most likely standard mustang specs which would be incorrect for your setup)

 

[bnickel]

have them set teh camber to .5 or 1 full degree of camber and that will help some. if it wasn't too bad (read livable) before you changed the BJ's this should get you back into the same are or pretty close. lot's of people run the same wheel/tire combo as you and it was basically the same combo that people back in the 60's used as well since that is (and als was in the 60's) the standard backspacing for the Torq Thrust series wheels. worst case scenario is you might have to go with a 215 tire instead of the 225

 

[ron67fb]

Have you seen where it's rubbing? With 225/60s it's most likely rubbing on the lower front edge of the fender, where the fender curves in. This is heard when the wheel is turned from straight ahead, and goes away when the wheel is turned further. The usual fix is shorter tires.

 

[mxmattd]

you were right dodgestang, they are 3.75

and you were also right ron, the paint is worn on the lower front edge of the fender on the passenger side, but the driver's side looks like its rubbing it the top of the fender.

what about removing some material from the disc rotor where it contacts the mounting pad? i think i could get away with 1/4 inch easily without running into problems with the calipers. that and a bit of negative camber would probably take care of it.

what do you think the cost of doing this would be? i'd like to compare it to the cost of going with 215 tires.

thanks for the help guys!

 

[02MGGT]

have you considered selling your wheels and getting a new set with different backspacing? You would have to run the numbers but it may be cheaper than the other alternatives. Just a thought....

 

[mxmattd]

i did consider it, but i think i'll try getting a realignment first. if that doesn't work, i guess i'll have no choice but to get either new wheels with more backspacing or skinnier tires. i hope the difference between 215's and 225's is not that noticeable, i love how agressive wider tires on the front look. personally i can't stand those super skinny front tires and fat rear ones.

 

[ron67fb]

Not much difference, take a look at this page:
http://www.miata.net/garage/tirecalc.html

I've seen 215/60-15s on '65/'66 cars and they fill the wheelwell nicely. 225/60-15 rubbed on my '67 so I can't imagine getting them to work on a '66. Machining anything is most likely going to cost more than a set of 215s, not to mention the safety issues that may arise from removing material from the hub and/or wheel.