planmgb
GT Owner
Looks great! NO rub or anything right. I already lowered mine like that, ironically mine is the same color. My wheels will be brushed with chrome outers. Doing the same 345/30/20 275/30/19
Lets talk wheels.....
- Thread starter txviper
- Start date
FBA
GT Owner
Your front should be a 35 profile at that size if you want to stay at stock wheel/tire height.
HOOKED ON GT
GT Owner
19 front and rear combo
I'm 40 and I just wet my pants.....+ my prostate is good to.
That unit there is so me.. dam boy!
More pics please...
Stuart
2112
Blue/white 06'
sahlman
Ford GT Team Alumni
2112; Glad to do it! Sorry I have been absent until recently. Had a blast at Rally 6. Will do my best to interact here more.
I have a lot of comments on wheel offsets. Has there been a lot of discussion on the functional/performance impact of wheel offsets? I was the guy who had to shove Camilo's concept car front wheel offset out from zero to 50 mm outboard for many reasons. And shove the rear out 40 mm.
Scott
2112
Blue/white 06'
Great!
So if a guy was to go to a 20"x13" rear wheel and 19"x10" front wheel, what does he have to do to keep the offsets correct (assuming he wanted the widest stance and fullest fenders?)
So if a guy was to go to a 20"x13" rear wheel and 19"x10" front wheel, what does he have to do to keep the offsets correct (assuming he wanted the widest stance and fullest fenders?)
Mullet
FORD GT OWNER
I just ordered a set of these in 18/19 sizes. Weight is the same as the BBS optional wheels. Price was in the ballpark that you would pay for 2 optional BBS wheels.
Picture them in matte black
Picture them in matte black
BlackICE
GT Owner
2112
Blue/white 06'
Who makes (made) the GTX-1 SEMA wheels? Were (are) they forged? Safe at high speeds?
What are the widths and backspacing of these? Are they still available?
What are the widths and backspacing of these? Are they still available?
2112
Blue/white 06'
Well a search provided this much;
Wheels; 6061 Alloy Corporation 19-inch front/20-inch rear
These are the wheels I am thinking of, seems there might be 2 variants and I prefer the deep dish style
Wheels; 6061 Alloy Corporation 19-inch front/20-inch rear
These are the wheels I am thinking of, seems there might be 2 variants and I prefer the deep dish style
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Mullet
FORD GT OWNER
Mullet
FORD GT OWNER
KJD
GT Owner
sahlman
Ford GT Team Alumni
I assume with the correct tire sidewall height to maintain the stock tire OD... From a function/performance standpoint I would maintain the stock wheel offset of 50 mm positive in the front and 40 mm positive at the rear. This will keep the same wheel center position, which is important to maintain what we call scrub radius and spindle length. I will describe the importance of the stock scrub radius and spindle length, but I can't say if this stock wheel offset and these widths you note will fill out fenders as much as you want (versus a reduced positive offset and deeper dish). And I am not sure on clearances to suspension components. For sure, as someone noted the tire profile can vary a lot between tires so you must look at that as well for clearances. The stock rear tires nearly rub the clamshell when pushed hard on a banked track like Texas World.
Scrub radius and spindle length are the lever arm length the wheel/tire has on the suspension/steering under braking/steering and just the tire free rolling (no brakes). More scrub radius will make the car less stable on the brakes, give you more kickback in the steering wheel while braking, increase the loads in the tie rods and toe links and increase the toe change while braking front and rear and affect resultant car balance. Also, the larger the scrub radius, the greater the tire "scrubs" making steering efforts less linear and increasing tire wear and making it less even.
Increasing spindle length (through less positive wheel offsets or otherwise) will increase wheel kickback/fight when hitting bumps when not on the brakes and increase rear toe change when accelerating. All bad for balance/stability, bad for tire wear and bad for tie rod end and toe-link life.
Example front wheel torque about the suspension in braking at 1G at 100 mph- the stock GT puts about a 44 ft-lb torque on the front steering axis in this event. Decrease the stock positive wheel offset by ½” with stock tires and the torque doubles to 88 ft-lb. Wider and/or grippier tires quickly change the ½” offset reduction to 100 ft-lb torque on the steering system. The original concept car wheel offset would have resulted in a torque in the front steering system near 200 ft-lb in this event.
I understand the desire to fill the wheel wells as much as possible. It definitely looks good…these are the functional tradeoffs (beyond package issues) with adjusting wheel offset to help get there.
Scott
2112
Blue/white 06'
Wow, great response. :thumbsup
So, if we went with a wider wheel, say 1 inch and split the difference putting 1/2" in the inside and 1/2" on the outside, would the torque created be the same as stock? And you have already answered the clearance question.
sahlman
Ford GT Team Alumni
I deleted my prior post on this topic because I screwed up a few numbers...mainly camber gains. I am very sorry for throwing anyone off that read it. I had pulled race car numbers out of my head instead of the GT.
Re-alignment- For sure re-align toe, and it depends on how much you lowered it and how aggressive you want to be on camber on the street. For sure, the safest bet is go back to stock alignment, but I thought you might want to know some of the tradeoffs. The two primary downsides of much more camber on the street than stock is rut follow/wander and tire wear (inside edge). More negative Camber increases cornering capability quickly, but it also tends to hurt straight-line performance (braking or power down) The stock GT static cambers we designed at -0.5 deg front and -1.5 deg at the rear. Negative camber is top of the tire inward from the front view.
The camber relationship front to rear HEAVILY influences the handling balance of the car so, the following is for those adjusting ride heights and resultant cambers.
The GT geometry has just over -0.5 deg/inch of camber gain in the front and -0.75 deg/inch at the rear. It has a little more camber gain at the rear to make the car more stable as you get more aggressive (more roll and travel) with the car. Therefore, if you lower the car 1 inch in the front, then the new static front camber (without re-alignment) should be about -1.0 deg. If you lower the back about 0.75", like many have done, then your new rear static camber should be about -2.1 deg. These new static cambers should make the car have a very slightly tighter balance (more understeer- a little less chance of spinning out) at the new lower ride height if not adjusted, because the rear camber has gained a little more negative camber than the front, as noted. Although I would leave this camber split alone if you intend on keeping this much camber...with the tradeoffs noted above.
As noted above, GT's balance (and most any car) is fairly sensitive to camber, so I would at least maintain the stock camber split front to rear at static ride height of -1.0 deg more at the rear. Less than this -1.0 deg camber split front to rear will make the car spin out easier, more than this split will make it less likely to spin. Hope this helps your re-alignment decisions. I believe the T/A shock guys recommendations for camber options maintain this camber split with various levels of camber for street versus the track.
Scott
2112
Blue/white 06'
another good one. Copy and past into the FGT file.
Thank you
I had this copied from an earlier post;
Front Camber -0.7
Front toe L/F -0.03 R/F-0.03
Rear Camber -1.5
Rear toe L/R 0.10 R/R 0.11
Thank you
I had this copied from an earlier post;
Front Camber -0.7
Front toe L/F -0.03 R/F-0.03
Rear Camber -1.5
Rear toe L/R 0.10 R/R 0.11
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sahlman
Ford GT Team Alumni
Glad you like the number example. The torque gets way worse if you start hitting bumps while braking.
Yes, if you split the difference you will maintain the wheel center position from stock and stock torque on the steering, which means you will keep the stock offset since offset is measured from the wheel center to the mounting face.
Note, I just deleted and reposted my ride height- camber alignment stuff because my memory failed me and I screwed up some numbers. High priests in the Temple of Syrinx made me do it...:biggrin
Scott
Yes, if you split the difference you will maintain the wheel center position from stock and stock torque on the steering, which means you will keep the stock offset since offset is measured from the wheel center to the mounting face.
Note, I just deleted and reposted my ride height- camber alignment stuff because my memory failed me and I screwed up some numbers. High priests in the Temple of Syrinx made me do it...:biggrin
Scott