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Discussion Starter #1
guys, I'm really having a hard time deceiding what to do tire-wise. I am in the process of getting the brakes wrapped up, which has always been the weak spot of the car, next to the driver and cheap tires that weren't really made for what I was doing with them. with 13" brakes up front, discs all the way around, and a new set of hp plus pads, the brakes should not be the problem anymore. I've been working pretty hard on the driver, to that leads me to tires.

Here are the specs on the car, for those that don't know:
'86 Mustang GT
Maximum Motorsports caster/camber plates
Tokico illumina struts/shocks
H&R Race Springs (800#)fronts only
Steeda 350# rear springs
Steeda 5-link-2
Cobra 13" front brakes
11.65" rear brakes
car usually runs about -2.75* camber, can't remember caster or toe, but as much as possible
oh, stock sway bars

car has great turn-in and minimal understeer with this setup, which I like, but has ZERO rear traction, even with staggered size tires (245/40F, 275/40-17R). needless to say it's a handful.

I got a great deal on some 99 Gt wheels, which i plan to use for track time. they are 17x8's and I'm unsure on the backspacing.

Here's what I'm contemplating:
Should I go with the nt-05 street tires, or the nt-01 R-comps? should I continue to run staggered sizes? Both tires seen to do well for what they are, as well as being worlds better than what's on the car. I've gotten a really good price on both particular tires, so price is not the issue. in the decision.

Tell me what you guys think, and anyone that has driven my car is more than welcome to chime in with their experience as well.
Thanks!
 

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Discussion Starter #2
need to rephrase that ZERO traction bit... it does have some, but doesn't seem to be as composed as other mustangs I've seen. Most of my instructors I've had in my 4-plus years autocrossing have applauded me on how well I handle the car,especially after driving it themselves. It's usually mid-pack of our numerous street-tire group locally, so I do know I have a lot left to learn, but the tires are in definite need of improvement.
 

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I take it you're referring to autocross usage, and I don't think you're going to get enough heat in an NT01 autocrossing them to get good use out of them. My guess is you'd be better off with the NT05, although I haven't driven them yet. I will soon.

But it seems to me any underlying lack of traction at one end of the car will still exist in relative form when you change all 4 tires. In other words, you might gain traction on the rear, but you'll gain it on the front too, and your rear end will likely still feel like it has little traction.


I would look into any adjustability you can get out of the 5-link that would improve your Instant Center, or perhaps try a softer rear spring.
 

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Local guy has used the NT01's for autocross and even on a hot day, the tires don't get really hot. Certainly not "in the range" for their optimal traction.

Don't get me wrong, there is traction there, good traction. But nothing that would mirror the traction levels on a road course or extremely large/fast(like 1 minute + ) autocross event.

I haven't used my NT05's for autocross...yet, but I was impressed with the grip and wear level while at the road course this past Saturday. Great tire, little to no fade-out towards session end. They talk to ya', though. ;)
 

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Discussion Starter #5
MFE, you are correct. I havent quite gotten the funds to afford full-on track time, so autocross is where I'm at for the moment. I am running a pretty soft rear spring for my setup, which is why I am confused about my lack of traction. Part of it may be my trac-loc needing a rebuild, which I just did about 10 months ago. I wish I had funds for both tires and a new diff, but the cards havent fallen that way. I need tires at the moment, so the differential will wait until later this summer or fall. I will try and back my rear shocks down and see what happens. I'm currently running the Illuminas at 2F/4R.

As far as temps go, our region usually runs 50-80 sec courses, so I really dont know how the temperatures would run.

2k2, Im actually glad you chimed in. What was the tendency for the tire to get greasy at the end of session? How many laps did you make on them in each session? I really dont mind a noisy tire, I like for my lady to let me know how I'm doing :evil:
 

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Honestly, they never really got greasy or at least from my non educated feel. I did end up over driving them towards my final sessions but that was mainly just to try where OVER the limit was.

I think I did around 6 or 7 sessions with about 12 laps each session....purely an educated guess on that. It was about 90* that day.
 

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Discussion Starter #7
That sounds pretty good to me... what made you decide on the nittos, rather than some of the others? I've got a couple guys from my local region suggesting the Kumho XS's or the Direzzas. Have you tried either of them?
 

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Price/size was the determining factor. I'm only comparing these tires to some Falken Azenis. At my driving level, i'm pretty sure I wouldn't be able to tell the difference between those other two you mentioned.
 

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I'll chime in too, I haven't run autocross like you but I do participate in road course (called high speed) autocross as well as HPDE's.

I have run staggered and non-staggered size tires and I'd say put as much tire on the ground as you can. I noticed a difference in running a 245/40 and 255/40 front to rear as opposed to a 245/40 front and rear. I took off the staggered set when I replaced them and lost two seconds per lap (on a 1.8 mile course) with the smaller rear tires. Eventually I was able to get better at driving but it took nearly a year to get back to the speed I had seen the year before with the staggered tires. I imagine if I had stuck with the other tires I would have ended last year two seconds faster than I did.

Also, my car also understeers much more than oversteers so your results should be better than mine. This was all with my stock suspension (minus struts/shocks and springs). The stuff in my signature is in process of installation so I have no experience with it yet. I do plan to run a 245 (or 255 if they'll fit) up front and a 275 on the back.
 

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Discussion Starter #11
well, removing the rear sway bar has crossed my mind, but I'm probably going to attempt to follow MFE's thoughts of adjusting the 5-link first and see what happens. probably try changing the anti-squat first, then adjust panhard bar height. what do you guys think?
 

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I guess its just me but I don't really understand the question. Sometime I can be a little dense and look past the obvious. When you say "no traction" what does that mean? On corner exit under throttle what is the car doing? Sliding, pushing, spinning?

I've got my five link set to the lower holes in the axle mount and the passenger side of the phb all the way to the top and used the play in the driver side to the bar to level.

If you wanted to increase rear traction. lowering the phb would increase rear grip, using the upper holes on the axle mounts will yield a higher Anti-Squat %, although I am not exactly sure what that number is. That too should help to contribute to better grip on corner exit.

I'm not sure what removing the rear sway would or wouldn't do. It depends on how effective that thing really is in stock form. That should help increase your rear grip too if the bar is effective at all at the expense of more push.

All of the above stuff should help with corner exit traction, I think. But the car will be more likely to understeer so you will be back to a point and shoot type of car.
 

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Discussion Starter #13
thanks for the input bullitt, you are thinking correctly. the car has pretty good balance, but could stand to gain a little more traction on corner exit. I still get quite a bit of on throttle over steer at exit, resulting in some assout antics. it's a hoot to drive, but not as fast as I feel it should be.
 

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Discussion Starter #15
My PHB is set all the way down on the right side, and most of the way up on the left (this was about the only way to get the bar level). Anti-Squat is set where steeda recommended it for non-abs cars-i forgot to double check before I left the house this morning. I'll have to check on the sways, too.
 

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As I understand it, the lower the intersection between the phb and the vertical midpoint of the rear axle, the higher the rear grip but at the expense of some added understeer. In your case, it sounds like that would be a welcome addition. It sounds weird that you could be all the way down on the right and all the way up on the left. I don't know it would be more important to have the bar level or to drop the driver side of the bar to gain a lower roll center.

Also, I think moving the mounting point up increases AS I guess, but that can be a PITA too.
 

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Discussion Starter #17
If I do any adjustments, I'll definitely be on a lift. I realized this weekend just how spoiled having one of those available made me, after finishing my brake swap on the fox. I'll try and take some pics the next time I have it up in the air, and see what you think.
 

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Discussion Starter #18
here are those pics for ya... Sorry for the lack of detail, these came from my phone, which for some reason took terrible pics this afternoon, which is rare

Here is where my UCA's are mounted:


Driver's side PHB:


Pass Side:


Yes I know the paint looks terrible... I should have painted it before I installed it, but was unable to spend time doing so, as I was using a borrowed lift. You can also see where I grafted the rear hardlines from the SN95 Car to work for the rear disc brakes.
 

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Discussion Starter #20
a poorly prepared paint job I think... it was painted when I got it, but it looked like a he didn't scuff up anything before he whipped out the rattlecan. I am still running dumps, but the turn away to the sides, rather than straight down, keeping the roaring exhaust and blowing dust to a minimum. I still haven't found anyone I trust to mangle my magnaflow tails, so they are still on the shelf. one of these days I'll get em back on.

on the subject of adjusting the 5-link, I think I'll just move the upper control arms to the upper mounting hole and see what happens. Anything else you would suggest?
 
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