8" to 7" TT2's

[nillabu]

Currently running 225/50/17's on 8" TT2's on the front of the malibu. I have done the Bbody brake swap so I needed at least 5" of backspace to keep em from rubbing.

The car sits pretty low and I don't have a problem with rubbing now, except once in a great awhile at a driveway or two. Would like to get the 225's on 7" wheels instead of the 8's. I'll explain why in a later post #-o

I can special order the 7's with a max of 4.75" of backspace from Newstalgia wheel for $302 each. http://www.newstalgiawheel.com/wheel_detail.asp?subcat3=1011103 Alittle high, but I can live with that if it narrowes the track up alittle and gives me alittle more tire to liner clearance.

The way I see it, I would gain about 3/4" of clearance from the outside of tire to the liner and about 1/4" on the backside. Backside is not an issue.

Question is: Am I correct?? What do you think? If so, I should have done my homework better when I was deciding which backspace and wheel to use before I bought the 8's.

Thanks,
Steve

 

[nillabu]

I said I'd tell ya why I want to get the 225/50/17's on a 7" rim or at least a different set.

Like I said I want to get the track narrowed a bit cause it looks alittle wide in the front due to the Bbody swap and I'd like alittle more tire to liner clearance. The 225's should be on 7" rims anyway.

Second, the 8" wheels were ordered with the max stock order 4-3/4" backspace. Much cheaper than custom made backspace. Knew I needed 5" of bs but ordered the 4-3/4" anyway. Thought maybe they'd be okay. They rubbed the liners bad so talked to my local machinist about machining 1/4" off the back of the mounting surface. He thought that was doable and shouldn't affect the strength a whole lot. He's an old gear head also and builds all his own "billet" everything. The wheels had conical seats with about 9/16" of mounting surface thickness. He indexed them perfectly on the milling machine and took the 1/4" off. Wa-La, 5" backspace. They run "true", balanced spot on, index on the hubs and rub only slightly at that odd ball driveway.

The machining left 5/16" of mounting thickness below the conical seat. The machinist assured me that that was plenty of material and strength considering the wheel design. I gamble only occasionaly :roll: so took another step to help me feel alittle better about changing the two wheels intregraty.

The wheels are made with a round recessed area about 1/8" deep around the conical seat.

It's slightly smaller than the washer for a shank style mag nut so they wouldn't work. Found that the late 70's, early 80's Corvette alloy wheel flanged nuts fit perfectly. They're one piece flanged nuts that have the .300" shank.

When mounted up, the nut flange fits in the recessed area perfectly and torques up spot on also. I've put about 500 miles on them since and haven't had to retorque. The flange contact area doubles the size of the conical contact area.

I wouldn't hesitate to drive the car cross country myself and would not be concerned about the front wheels. I have 9 grandkids, the oldest being 16 this summer who already has asked about taking it for an afternoon sometime. That would make me feel uncomfortable knowing he would not know what to expect if something did happen. Now I'll spend more and do what I should have done the first time around. Anybody need two 17x8" TT2's? Will be letting them go once the others get here.

Shouldn't have done it to begin with but like I said, I only gamble occasionally ](*,) Might be alittle lesson learned here huh.

Steve

 

[86GUTLASS]

Intrested in the 17x8's Pm sent

 

[melloelky]

i can't see the lug nuts you described so i have to ask, why did you switch to them?did taking 1/4 off the back of the wheel change any in the lug nut department?

 

[nillabu]

melloelky,

Must have deleted the lug nut pic in photobucket, sorry. Yeah, wheel is thinner at the lug area from the conical seat in toward the hub. 5" backspace now compared to 4.75" before machining. Can still use the conical nuts but felt a shank style w/flange nut would be better (more contact area with flanged nut) I'll try and get a pic up. Wheels are still available by the way.

Found it

Steve

 

[melloelky]

ahh i get it now,thanks.i ask because I'd like another 1/8 or so backspacing and was thinking of talking to a machinist i know about taking a little off the back of my wheels.the wheels are tight but they do clear.another 1/8 would be nice.

 

[LS6 Tommy]

Did you fill in the conical seat with a weld? If not, you REDUCED the area of contact between the lug nut flange & the wheel. Can't post a picture or anything, but think of it as putting a pan head screw into a hole for a flat head. The only contact area is the small circle where the very outside edge of the lug nut flange touches the conical hole. It also over stresses the flange on the lug nut because it's not fully supported by the wheel. Big no-no from back in the days of Unilugs & shanked lug nuts...

Tommy

 

[nillabu]

Nope, didn't fill the conical seat with a weld Tommy. Forgot to mention that the shop drilled the lug holes out to 45/64" (.7031"), standard shanked hole size is .690") from the original TT2's .630-.635 hole size to fit the OEM Corvette shank (.7025') style nut. Yep, as you can see, there is a slight edge remaining from the original conical seat after drilling. All five one-piece flange nuts fit perfectly into the wheel recess, supporting and centering the wheel on the hub. Yeah, probably a NO-NO if you're gonna autocross the car mainly because of the the reduced wheel flange thickness but never a problem driving normally. Didn't necessarily want to adjust my backspace this way but did what I thought I had to at the time.

 

[LS6 Tommy]

I get it. Your picture explains it all. I guess you can "disregard last transmission". :lol:

Tommy