Can I get schooled on 1/4 mile? Tire - Suspension Technique

[Monera3v]

Hello everyone,

This year I would really like to get my car into shape for 1/4 mile runs ( And maybe some course runs )

Car is a
2005 Mustang GT with a M90 blower making 400hp 400 tq, 5 speed

I am trying to get the car to grip a lot better and lower my nasty 2.1 60'

Setup wize I am running
Tires:
255/40/18 BFG kdw in the front
295/35/18 bfg drag radial in the rear

The results are

SPin spin spin spin city!

https://www.youtube.com/watch?v=PU31tnWXvNc

Suspension wise as follow;

Ford racing K spring (1.5" drop)
UPR HD hem join lower control arm w/ BMR relocation bracket
BMR HD upper control arm *poly bushing* with BMR upgraded bracket
BMR Pan bar
RTR Sway bar
Tokico hp shocks

Will be swapping out to 3.73 unless someone advise other wise?
Rebuilding the rear end and tlock


If i should change anything please advise.


I don't want to switch up to a Big n Small wheel / tire setup.

What tire should I look into getting for the rear? Even if it means buying new wheels I am fine with that.

Any info would be much appreciated!

Best so far I have done is 13.1 ~ 109mph
With 3.55 and full stock weight

7748

[Laffs]

Seat time. Play with launch rpm and technique see what works best. Also try doing a longer or shorter burnout, drag radials don't need to be smoked in to oblivion but you need to put some heat in them. Big diameter drag radials and a stick with a lowered suspension isn't ideal for great 60ft times. Not wanting to go with slicks on bigs and littles limits you so perhaps a 15-16 inch wheel and drag radial.

Gear ratio, you are going to get more spin from a higher ratio so you will have to practice more once you go in. Pick which ever ratio will get you close to trapping close to the top of 4th gear is what I was always told.

Suspension wise if you really want it to drop the 60s ditch the lowering springs and the stock replacement struts for something that will let the car transfer more.

Aside from that put the car on a diet for the track, pull the spare tire, stereo, rear and passenger seats before the track day. A basic rule of thumb is that every 100lbs you pull off the car will net you 1/10 in the quarter.

[Slick_89_Hatch]

I would check instant center or at least play with the different locations for mounting on the relocation brackets.
Play with your burnouts and tire pressure also. I found things worked well for me around 18psi with my 235/55R15 MT ET Streets.
Next would be change rear tires and rims IMO. Nick has good success with his 17" ET Streets. I'd see what his set up is as well.

[Monera3v]

I am hoping that
Rebuilding the rear end + the TLock will give me some tracking
I also think my shocks were blown, hoping those factors are to blame for some spinning.
I am looking at some BMR drag springs? Would it make a difference?

So I was told not to mix bias with street tires?
What kind of tire do I need to look at to continue running my street rubber upfront?

[Slick_89_Hatch]

I really think the MT ET Streets are the way to go, especially since you can drive to the track with them. If the shocks are indeed blown and tloc is not functioning then those are huge factors as well. I wouldn't worry about drag springs until your other issues are sorted out.

And to my knowledge (which isn't alot on this) mixing bias and radial are a receipe for wobble.

[TC86GT]

First off don't fear the gear. To me going from a 3.55 to a 3.73 wouldn't be worth the effort. Step up to a 4.10, especially on a bigger/heavier '05 GT.

Tires, 15" set-up with a sticky slick or DOT type of slick. Bias ply will be your best bet, even if it spins the recovery will be quicker and still push you forward. If you had an automatic, I'd probably suggest a radial but typically the radials and manuals are a tough animal to tame.

Mixing bias ply and radials, yes you may get some "wishy washy" feeling at speed but it's far from an uncontrollable thing. Just keep it pointed forward and run it out the top end. I've done it both ways, bias ply in the rear, radial up front and bias ply in the front and radial in the rear. Never felt unsafe or out of control.

Sure you could swap out the suspension for a better drag oriented set-up but you can't have it both ways. Stiffer for cornering and straight line grip...one or the other or a happy medium for both. If you are satisfied the way the car is now, just gear it up, and throw on some sticky tires. 109mph is good for mid 12's easily, but the 2.0 60' is killing you. Get that into the 1.6's on a sticky tire and you'll be looking at a half second decrease on ET just leaving harder.

My current '86 GT is lowered, stiffer springs and shocks/struts and when it was a 5 speed/4.10 combo, I had 16" radials up front and 15x8 wheels with a 26x8.5 slick out back. It'd go mid/high 1.6 60' times on motor running high 12's and on the bottle it left with a 1.52 best 60' dropping into the 11's.. Definitely not a drag suspension under it, but with enough power and enough traction...it'll go.

[WidowrRacing]

I would recommend starting with a slick mounted on a 15' rim and then you can actually get a decent baseline and mod your car from there. Your car will only get faster with traction not being an issue.

I'm so done with the low profile drag radials.....don't get me wrong they're great for the street but not the track....just not enough side profile for a consistent hard launch.

[Monera3v]

Can anyone recommend a tire I should go with?

[TC86GT]

Full slick, MT or Hoosier 26x10 on an 8-10" rim.

DOT slick, Hoosier Quick Time Pro or MT ET Street bias ply in 26x11.50.

Plenty of tire that will take you well beyond your current level. Toss them and a jack in the trunk and swap them at the track.

Don't forget to put on a driveshaft loop if you don't have one already.

The '05+ cars are 31 spline axles/diff so they will take some power in stock form.

[WidowrRacing]

I think the 35 series profile is the problem for track use with your current DR's

You would have much better results with a 275/60/15 DR or a full slick in 15'.

Latemodel resto offer SVE drag rims and tires in 15x10 for your car with an optional skinny if you want it....these are cheaper than others unless you can find a good deal used.

Mickey Thompson or Hoosier seem to be two of the most common tire choices.

[Monera3v]

I am no expert but someone is selling me 28x12.5x15 tire
I am currently lowered on ford racing K springs

If I get the correct 15x10 wheel with 7.5" spacing I don't know if they will rub.
they are MT ET bias ply *slick with 5 grooves along the surface.

Would that be too much for my car?

[Monera3v]

This is from the sller.
Very confuse what he stating... bout 12.5 but they are really 10"

" Mickey Thompson 28x12.5x15 ET Street Bias Ply. These are the same width as a true 28x10 slick. 12.5" is the section width (it's how they classify et streets).
Lots of tread life left. $260 "

7759

[TC86GT]

28" tire is a lot of tire. You have to accelerate that mass and the height and growth will kill your effective overall gearing. I'd stay with a 26" tire, which when it grows at speed will be very close to your stock tire height and keep your rear gearing unaffected.

Too much tire is not a good thing. Dean's ET Streets are a great deal but very likely more than you need.

[ZR]

-Rebuild / fix the posi unit
-go with more gear
-tire advice above is rock solid

Practice / practice then practice more.

[Monera3v]

28" tire is a lot of tire. You have to accelerate that mass and the height and growth will kill your effective overall gearing. I'd stay with a 26" tire, which when it grows at speed will be very close to your stock tire height and keep your rear gearing unaffected.

Too much tire is not a good thing. Dean's ET Streets are a great deal but very likely more than you need.

Ahh so we are aware of the seller.

Yea, I think ill pass on them and stick to something a bit smaller..

[Monera3v]

-Rebuild / fix the posi unit
-go with more gear
-tire advice above is rock solid

Practice / practice then practice more.

Gear 3.73 for sure
Tire advice has been understood and taken will search for a better set to suit my needs
Will be hitting up the track with a few vets who have offered to help me out

Thanks Y'all!

[Ray721]

Full slick on 12psi 7500RPM clutch dump YOLO!!!

[Monera3v]

Full slick on 12psi 7500RPM clutch dump YOLO!!!

LOL ... my RPM pegs are 6500 LOL

I am no Raul Mr Ray! lol

[Ray721]

#3vproblems lmao!

[allicedout]

I am no Raul Mr Ray! lol

Don't give up..... You'll get there eventually! :D

[Monera3v]

Don't give up..... You'll get there eventually! :D

Rod through the block, no thanks :)

[NickD]

What's the current tire height, and what is your rpm going through the traps as is stands (and which gear) you need to optimize gear and tire height to take advantage of the power you have, it doest help having a steeper gear if you hit redline 50feet before the traps.

Sent from my Nexus 6P using Tapatalk

[TC86GT]

From the online calculators (http://www.wallaceracing.com/Calculators.htm) I'm seeing just under 5000rpm the way it sits now. 3.55 gear, approximately 27" tire if it's near stock size and 109mph through the traps.

Plugging in 4.10 gears, a 26" slick and 109mph is just about 5800rpm through the traps, but doesn't take into account the bias ply growth. So slightly less in reality.

In an ideal world you want to finish up the 1/4 a few hundred RPM past your shift point. So if the shift point is an even 6000rpm, even with 4.10 gears it's still slightly under-geared.

These calculators would be based on no slippage and a 1:1 ratio (typically 4th gear). If it was an automatic set-up, then there would be more RPM due to the converter. I've found them to be pretty close in the past.

[NickD]

I trapped 109 NA and have 4.10s with a 26" tire, I know for sure with boost he's at least 115 or higher (I am anticipating 120 or just above with my setup and am likely going to have to run a 28 or 29" tire.

[ttpinto]

I would run a 15" Et Street R. Its a dot legal drag radial. They are an amazing tire. I have cut a best 60 ft of 1.29 with them. I'd work on getting the car to hook, every tenth in the sixty equals 2 in the quarter. Those bfg's arent helping you, start with tires and then start chipping away at the rest.

[TC86GT]

I trapped 109 NA and have 4.10s with a 26" tire, I know for sure with boost he's at least 115 or higher (I am anticipating 120 or just above with my setup and am likely going to have to run a 28 or 29" tire.

Going by what be posted he's running 109mph with the blower from his original post. Just using the info I was given to plug in the calculators. Plugging in a 115mph trap speed without factoring in tire growth, puts trap RPMs at about 6000rpm with the 4.10's.

Ron, I'd like to try a set of the new R's myself, but the automatic and radials go together so well, my only concern in this case is recovery on a spin. I know the bias ply tires and manual will still push forward even with some spin.

[Monera3v]

I am going to give the BFG a another few tries once my rear end is rebuild and redone
def doing 3.73 during the rebuild process.

- - - Updated - - -

Should I go with a 26" tall tire or 28" tall tire? I have a 1.5" drop in the rear with Ford racing k spring.

[TC86GT]

Not enough power or gear to warrant a 28" tire, stay with the 26" tire, it will work best at this point.

Next time out with the BFG's, drop the pressures low and cook them in the burnout. With my limited experience with them they like to be treated almost like a slick, whereas an MT drag radial like more pressure and less heat.

[Johnny5.0]

Here's some food for thought...when I had my 85 I was at the track almost every weekend. On real street tires it ran 13.20's@109. On drag radials it ran 12.80's@109, on et streets it ran 12.40's @109. This was a stick car as well.
As TC has mentioned....stick with a 26" tall bias tire, you'll get quicker times and they're easier on the driveline when used on a stick car.

[NickD]

Et street r is available in both radial and bias, the ones given as measurements are bias the ones shown as traditional tire sizing are the radial and same compound as the et street pro 275 tires.
I didn't notice the 109 trap speed, was that in the heat? Seems low as I ran the same with 330ish HP. (Trap speed is about power independent from ET)

Go to the track with Ron he'll inspire the f*ck out of you and you will push the car into the 11s, super nice guy with a wicked car.

[TC86GT]

stick with a 26" tall bias tire, you'll get quicker times and they're easier on the driveline when used on a stick car.

Good point worth mentioning, on a radial tire, if they spin and get into tire shake...that's hard on parts. Axles, diffs, wheel studs...pretty much the entire driveline. A bias ply spins, that's pretty much it, slips until it grabs. Radial drag tires are amazing, but they can have drawbacks.

[Monera3v]

Et street r is available in both radial and bias, the ones given as measurements are bias the ones shown as traditional tire sizing are the radial and same compound as the et street pro 275 tires.
I didn't notice the 109 trap speed, was that in the heat? Seems low as I ran the same with 330ish HP. (Trap speed is about power independent from ET)

Go to the track with Ron he'll inspire the f*ck out of you and you will push the car into the 11s, super nice guy with a wicked car.

With all the spinning I do in 1st. I lost a lot of speed.

[Intmdtr]

As already stated, don't change anything except having your rear end built. It may surprise you what the car will do with a functioning rear end. Rebuilt my rear end about 6 yrs ago and took nearly 1 sec off my ET with nothing else changed. If you know the rearend isn't functioning correctly, don't throw money at anything else trying to solve problems. if you do hunt some rear tires down I wouold go with a MT ET street 26x11.5x17 if you already have 17" wheels. best tire I ever had before switching to a big and little setup with hoosiers.

[Speedtospare]

Agreed with the above 15x10" rim 7.5 backspacing, 15x26" Bias ply slick (better for stick car) I do like the feel of MT drag radials on the big end. 3.73 or 4.10 (I like 4.10's). Get your tire pressure right. Mine Hoosier slicks like 11.5 psi. I had a ford racing 31 spline diff with the carbon Kevlar clutches and I wasn't that impressed. Clutch packs lasted a year and then one wheel peel. I put a Detroit truetrac in and maaaaaaannnn do I love it. Car drifts on demand and Hooks nails. Remove any extra weight from the car, lighten the nose if by moving the battery to the trunk. Every -100 lbs is worth about a 10th
in the quarter

Will a 15" rim fit the brakes on a 05 GT without mods?

[Monera3v]

Agreed with the above 15x10" rim 7.5 backspacing, 15x26" Bias ply slick (better for stick car) I do like the feel of MT drag radials on the big end. 3.73 or 4.10 (I like 4.10's). Get your tire pressure right. Mine Hoosier slicks like 11.5 psi. I had a ford racing 31 spline diff with the carbon Kevlar clutches and I wasn't that impressed. Clutch packs lasted a year and then one wheel peel. I put a Detroit truetrac in and maaaaaaannnn do I love it. Car drifts on demand and Hooks nails. Remove any extra weight from the car, lighten the nose if by moving the battery to the trunk. Every -100 lbs is worth about a 10th
in the quarter

Will a 15" rim fit the brakes on a 05 GT without mods?


Yes sir, 15" will fit no problem
06+ will have to grind the caliper.

[Monera3v]

so Ive come to a conclusion.

Hoosier all around (y)
26"
3.73 gears
Sve wheels

might even do runners mid way through tthe season if i feel comfortable =)

[NickD]

I've seen you post about feeling sway at the big end, running bias ply rear with wide radial fronts will accentuate that, get matching bias front from the get go. Also if you figure out your low mph out I'm thinking your going to run out of gear with that combo based off my own experience

Sent from my Nexus 6P using Tapatalk

[Monera3v]

Going to fix everything with 3.73 gears
Adjust tire size after my first track day (y)

[ttpinto]

so Ive come to a conclusion.

Hoosier all around (y)
26"
3.73 gears
Sve wheels

might even do runners mid way through tthe season if i feel comfortable =)

Are you going drag radial or slicks? If drag radial run a MT Et street R, they hook better than the hoosiers. Trust me I've run both. Slick run either, both work good but might want a stiff sidewall to get rid of the sway on the top end.

[Darkhorse]

What is your goal ET with the car?

[TurboFox]

holy shit. These were my tires for sale. Dude they were pretty much new and only $260 LOL...what else do you want.

Sure enough they sold to the first person today after I held them all week for you......

And once again...the bias ply ET streets are labelled by section width NOT tread width

A 28x12.5x15 Bias ET Street is the same size as a 28x10x15 ET DRAG.

[Monera3v]

What is your goal ET with the car?

7852
low 12s?

[Monera3v]

holy shit. These were my tires for sale. Dude they were pretty much new and only $260 LOL...what else do you want.

Sure enough they sold to the first person today after I held them all week for you......

And once again...the bias ply ET streets are labelled by section width NOT tread width

A 28x12.5x15 Bias ET Street is the same size as a 28x10x15 ET DRAG.

Yea even thought they were cheap.

Everyone has ruled 28 out an recommend I stay with 26 due to gearing

and its true. anyone running my setup with an s197 is running 26 with stock 3.55 s/c

[TurboFox]

Sounds like good research you could do BEFORE committing and having me hold them for a week...

My fault for holding them I guess.

[Darkhorse]

If you're at consistent 13.1's at 108-109mph, then to take a full second off your time that's a call for major changes.

I remember your threads from last summer and I feel the car already has 12.70's or 80's just by cleaning up your burnout, stage and driving including the rpm you leave at.

also, a soft sidewall slick on a stick car will be very hard to handle and harder on the drivetrain, there are guys going high 7's and low 8's on D/R's so at your power levels you can easily still go faster without a slick.

[Johnny5.0]

^^^^...please explain how a soft sidewall type tire is going to be "harder" on a stick cars driveline??

[Monera3v]

wrong post (deleted)

[Slick_89_Hatch]

My Fox went from 12.9 to 12.1 just using 235/65R15 ET streets vs 275/40R17 Nitto 555R's and disconnecting front sway bar. Sort out your rear end and a good burnout like Darkhorse said should get you mid 12s at least IMO.

[Darkhorse]

^^^^...please explain how a soft sidewall type tire is going to be "harder" on a stick cars driveline??

A soft sidewall slick will crinkle more wadding up and even roll over on launch and when banging gears. This will cause the chassis to flex more. A stiffer sidewall slick will provide a bit more damping like your shocks do to keep you a bit more planted, but more chance to spin the tires. A stick car will also be naturally harder on the driveline, it's the same reason IRS cars will wheel hop less and break less half shafts with an auto as compared to a stick.

[Johnny5.0]

I agree that a stick car is naturally harder on the drive train than an auto car, but that's why a bias ET Street type tire works better imo. Yes, there's some wrinkle of the sidewall during the launch, but this is what cushions everything from the input shaft back to the axles. At the OP's power level the tire will never wad up or effect/upset the car unless he was to run say 4-6psi which is not required at this power level. It will be a bit of a learning curve to get used to the "sache" of the bias tire down track but that's easily overcome by starting out with a higher psi in the tire and gradually dropping down as the comfort level rises. I don't have any experience with the new MT "R" DRs but I had both BFG and MT DRs and the launch was violent compared to the ET Streets and slower 60' times to boot!! Just my two cents....

[allicedout]

http://www.dragzine.com/tech-stories/wheels-tires/dot-drag-radials-101-what-you-need-to-know-about-drag-radials/

[Rino]

Went to Cayuga quite a few times this past summer.There are so many variables, Tack temp,air temp, tire pressure, reaction time.I ran my street tire, "Michelin pilot super sports",looking for slicks and rims as I type this . Had trouble putting the power down. Spinning tires banging 2nd.My best time was a 12.88,and I spun 1st, and then 2nd.Plan on getting a slick,to get where I should be.Ive drag raced since I was in my teens.Practice ,practice,practice. The other guys at the track will help you, if you talk to them.Ask what tire pressures they are running what rpm ,etc ,etc.The track is different every time you go, from the last time.Be prepared to change things,to get the best out of the day.

[Armen]

^^^ Did you do a burnout?

[Rino]

tires are too expensive to do burnouts,lol
^^^ Did you do a burnout?

[Armen]

tires are too expensive to do burnouts,lol

Ya, that's why I asked, lol.

I have the MT Sport Comps. I did do burn outs cause much less expensive :D

But they've been a really good tire. Road course, strip... Nice grip but still durable.