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Better 60' times ?

4K views 17 replies 7 participants last post by  Dadstoy 
#1 · (Edited)
Can some of you more seasoned track guys fill me in on how to get my 60 foot times to below 1.8. I currently run a 295 wide rear tire with stock suspension and my 60 foot times rarely reach below 2.5 thus making me run in the 14's, which is garbage. Are slicks the only option? Has anyone seen improvements with Afco coil overs or even the hop not kits. I am a technician by trade and oldschool denotes suspension, slicks etc. I don't want to throw money at this problem. Any help would be appreciated.

09 SRT 6 speed
Rear reso deleted
Roto fab CAI
93 tune with predator
180 thermo.
 
#2 ·
Go for that full-on 4.10 axle, eh? On the 6-spd manual, seems like you need to get as much gear out of 1st as you can get to really put those sticky 295's to work and getting 4200 lbs of car to move.

If you're already breaking them loose, have you tried reducing tire pressure in the rear?...not the best thing for just driving around, but specifically for those instances when you are whittling down the 60 ft time?
 
#3 ·
Better 60' times?

Well I mean the SRT already has a 3.92 gear ratio so moving up to 4.10 isn't a viable option. I have ran my Tires as low as 26 psi with the same results. I would like to know if anyone has just used DOT Drags in place of a normal tire with no suspension upgrade other than lowering springs and seen 60' times of 1.6 to 1.8.
 
#5 ·
Other than the money, why isn't a 4.10 a viable option?

Are you experiencing any wheel hop when launching hard?
 
#6 ·
Oh yea wheel hop is an issue I can't leave the line under power. I have to feather clutch for the first sec or so. As for 4.10 gears increasing a gear ratio by .18 only equate to maybe .2 or .3 on the big end and even more traction issues on the whole shot. Considering my current situation. I have two stock rims that I will put 275/40 nitto dr's and revisit.
 
#7 · (Edited)
Well, there's a pretty significant bottleneck, if you are experiencing wheel hop...don't you agree? If it seems like it is bogging with too much traction, otoh, then the 4.10 axle would have made more sense (otherwise, I would agree that it would just worsen the WH).

Sounds like you might stand to gain with "less" traction, so the tires slip more gracefully, rather than "chattering" in a wheel hop? Aside from just adding a HopNot kit, have you experimented with higher pressures instead of lower? Between the 2 scenarios of grippy + wheel hop vs less grip + some slip, both will lose time, but maybe the latter is a bit easier to control and modulate in order to be get into a WOT phase earlier? If you can't shake the WH no matter what you do, then you just have to ante up for one of those kits, I imagine...

Also note, that just the action of exploring various techniques to ride that WH threshold w/o getting WH, but still yielding WH, can eventually do some damage all by itself, if the WH is intense for too many times. Things back there will "loosen" up to the point that WH then appears at the drop of a hat as well as possible whining diff issues popping up.
 
#8 · (Edited)
I did try various air pressures. I started with 36 went down to 28 then back up in 4 pound increments with 2-3 runs per. I like the idea of the hop not kit but not sure it will fit with my 295/30-22's. I'll have to contact those guys to see if the new wide tire brackets will accomidate. In the mean time I'm going to buy a set of 275/40-20 from Nitto to see if I can pull a better number. If wheel hop occurs then hop not kit or coilovers is the next upgrade. I am assuming the wheel hop is the tire fighting for traction. Which is always the case using a street tire. I hope the drag will allow a small amount of slip and continue to hold traction and hopefully decrease if not completely eliminate it.
Thanks for your feed back. I wish dodge would have taken rear suspension cues from from Ford because the five link system is killing me at the track.
 
#9 ·
Wow!...30 profile tires on 22" wheels sounds like not much sidewall to help cushion the launch jolt. Seems like you should be exploring "fatter" tires as far as sidewall. The 22" rim is also a lot of metal far out fom the axle, which is probably not helping as far as rotational mass and optimal acceleration times.
 
#12 · (Edited)
I'm by no means an authority on the matter, but my curiosity leads me to propose that the anti-squat geometry in the rear needs to be eliminated altogether, maybe stiffer rear springs (and higher damping shocks) to better resist squat, and wide tires that are grippy, but not necessarily the most grippiest of compound.

I suspect that modern tire technology has produced some very grippy tires to the point of behaving like "over unity" levels of grip. That is, generating more traction force than the force that bears down on them (via car weight and weight transfer), whereas a more "natural" relationship is the traction force is some fraction of the force bearing down (albeit, a high fraction to be desirably grippy). When you get "over-unity" style traction, I suspect nasty things happen if/when traction is exceeded. Being that the force bearing down (in order to facilitate the maximum traction force) is not as high as it could be, the tire will be prone to pop up off the ground in response to the rolling friction (grip) overloading (and then collapsing). This cycles rapidly during an overload condition, and from this we observe the phenomenon of wheel-hop. The design of the tire tread for maximum rigidity for optimal dynamic response probably exacerbates the wheel hop behavior, as there is no "give" to allow sudden reactions to dissipate.

Hence, returning back to the idea of a "less" grippy tire...something with a more linear (natural) response of force bearing down relative to traction grip and appropriately wide to assure plenty of headroom in potential grip via "adhesion" properties.

An alternative to relocating suspension points to zero out anti-squat, I am curious if the same thing could be achieved by simply using rear tires that are oversized in tire height (and/or similarly using front tires that would lower the front of the car)? Yes, literally raising the back of the car so the anti-squat geometry goes from x number of degrees back to nearly zero degrees from horizontal. Could that work?...wish somebody was bold enough to give that a whirl! ;) (Mind you, that is different from just jacking up the rear with creative use of springs, as the control arms in such a position is probably causing all sorts of funky things with camber and toe, that would not be typically desirable in the rest state.)
 
#13 ·
Install a Hop Not kit. They offer options for wider wheels and tires. It won't completely eliminate WH on a sticky treated surface, but it's a big improvement. On the street, it's almost a complete cure.

Randy is totally correct - you need more sidewall for some flex. A 30 aspect street tire has a very stiff sidewall - hardly the recipe for a smooth launch with an M6. I recommend a 18" wheel and a 275/45/18 M&H DR and run them at about 20 psi for track work.
 
#14 ·
Also, the point of shorter gearing with the M6 is to avoid dumping the clutch, shocking the drivetrain, and inducing WH because you are trying to get 4400 pounds moving without the aid of a torque converter. A 4.56 gear will allow you to move it off the line with less drama and without blowing off the tires. And it will still wind-up quickly and give you a decent short time.
 
#15 · (Edited)
A 4.56 axle also lets 4th gear to properly stretch its legs in a 1/4 mi run. :) Might be able to go even shorter than that on the axle and still not be getting to redline in 4th at 1320 ft.
 
#16 ·
Thanks for the hints Heminator.Ive got a 2012 R/T with STP,Chromeclads(goodyearF1s) with the 3.92s.Ive only made 3 passes.1st pass 14.25@97.40 mph with a 2.187 60ft.Second pass lowered the rears to 26 pds and went 14.16@ 99.82 with a 2.199 60ft.Third pass went into wheelhop. This was shifting around 5500.Ive got some 18 inch wheels and Im thinking of getting some DragRadials and see what happens.Plus raise the shift point to around 5800.Biggest problem Ive had is launching at the same rpm every pass.Been years since ive gone down the 1/4 miles and its just as frustrating and fun as it was years ago.LOL.
 
#18 ·
post up a timeslip and I will add you to the 392 and top 50 list.
 
#17 ·
I can cut fairly consistant 1.8's on factory good years but I have an auto tranny. try doing a nice burnout and leave at 1000rpm. you have steeper gears than the auto so I can't offer much advice. with my red TA, I lanched at 6500 rpms but the car was built for the 1/4 mile with 4.56 gears and slicks.
 
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