60 ft trouble

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hotrod68

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I wrecked the 8 3/4 3.91 gear in my dart last year and replaced it with a 4.10 geared dana 60, I also moved the springs back 1 inch for drive shaft reasons, this car used to dead hook and do 1.39 60 foots with ss springs and a snubber on a 30x9 slick with a best of 10.12 @132 now with the dana I can feel the tires slipping and my 60 is 1.48 to 1.52 did moving the rear end back cause that much weight transfer problems or is the gear difference to much for the ss springs to handle? It has the same pinion angle, snubber clearance and shocks as before maybe its time to upgrade to the caltrac system? even with the crappy 60 ft the car went 10.13 @ 131 so if I can get it out of the hole I'm sure the car will like the new gear ratio. Any thoughts?
 
Spinning? Maybe old setup was on verge of traction limits? Now more gear is making spin? Also moved Suspension pivot point back thus hurting weight transfer
 
I would get someone to video the launch and slow the video down to see what is going on.
As an example, the tires may hit, rear unloads and tires spin; or tires spin immediately.
SS can handle 4.10
How many times have you had the car out? Could it have been track prep? Have the tires dried out?
 
mderoy340 said:
I would get someone to video the launch and slow the video down to see what is going on.
As an example, the tires may hit, rear unloads and tires spin; or tires spin immediately.
SS can handle 4.10
How many times have you had the car out? Could it have been track prep? Have the tires dried out?
Click to expand...
moving the rear-end back took a ''small?'' amount of weight of the rear wheels .
 
testing the car again this weekend and will video to see what is going on, the tires are good and after talking to a few others at the track they were also having issues, I'll see what happens tomorrow
 
How old are you slicks? Could be that your slicks were on the border of losing traction. And with the lower gear (3.91, to 4.10's) put you over the edge of traction...........the track, traction, could have been marginal as well, as you have mentioned.
 
The short front segment of the mopar spring is what gives it leverage to plant the tire....moving the rear end back decreases this effect....food for thought
 
hotrod68 said:
I wrecked the 8 3/4 3.91 gear in my dart last year and replaced it with a 4.10 geared dana 60, I also moved the springs back 1 inch for drive shaft reasons, this car used to dead hook and do 1.39 60 foots with ss springs and a snubber on a 30x9 slick with a best of 10.12 @132 now with the dana I can feel the tires slipping and my 60 is 1.48 to 1.52 did moving the rear end back cause that much weight transfer problems or is the gear difference to much for the ss springs to handle? It has the same pinion angle, snubber clearance and shocks as before maybe its time to upgrade to the caltrac system? even with the crappy 60 ft the car went 10.13 @ 131 so if I can get it out of the hole I'm sure the car will like the new gear ratio. Any thoughts?
Click to expand...
Buy cal trac mono leaf rr springs, cal trac bars, cal trac 9 way Adj rr shocks and cal trac 90/10 frt shocks AND THEN U CAN FORGET ABOUT ANY AND ALL TRACTION PROBLEMS....
 
I would start with there shocks, and keep your SS Springs!:thumbsup:

A video would help a lot. So you can see rear as well as right from tire.
 
Well I ended up buying the whole cal trac set up including springs and shocks, I'm also having the driveshaft shortened so I can move the rear end back forward to where it was, and the slicks only have about 25 runs on them, I'll let you all know how it turns out, thanks for the thoughts.
 
I'd try the cal-trac set up before I spent the money having my driveshaft shortened. IMO if moving the rear end back 1" causes traction problems you were going to spin on mediocre tracks anyway. You could've put a little weight in the trunk too to see if your 60' came back.
 
hotrod68 said:
Well I ended up buying the whole cal trac set up including springs and shocks, I'm also having the driveshaft shortened so I can move the rear end back forward to where it was, and the slicks only have about 25 runs on them, I'll let you all know how it turns out, thanks for the thoughts.
Click to expand...
You did the right thing....with the complete CalTrac setup....shocks, bars and mono-leaf springs plus Cal Trac 90/10 frt shocks.
Be sure and do the following on your Cal Trac Setup:
1) after installing the mono-leaf springs and before you install the 9 way Cal Trac shocks make sure you don't "overtighten" the rear shackles. Getting one guy on each rear fender you should be able to start pushing the rear end up and down and almost "bounce the rear of the car like a basketball".
2) With a foot-brake launch set the shocks on 9, stiffest setting.
3) Call Cal Trac Tech and tell them your set up and they will recommend a settings for the pre-load.
4) Make sure your front A-Arms allow the front end to move up and down easily...I rebuilt mine..
5) You need 5" of free front wheel travel. You want the front end to come up 5" on the launch before the tire lifts off the ground. To get this 5" of front wheel free travel I just loosened up my torsion bars and let the front end "sag". To measure the front end free travel, merely put a yard stick up to the lip on your front wheel well. Lets say it measures 34" at rest...then put a jack under your k member and jack up the car...the car should lift 5" before the front wheels come off the ground...the front tires should lift of the ground when the measurement is then 39".
I did the install exactly like this. I run 16lbs of air in my 28" M/T ET Streets ( you will have to experiment with yours for best tire pressure) and launch at 3000RPM off my foot brake (no trans brake). (Cal Trac recommends launching at 3000 RPM to "shock" the rear end...I have a 5000 Flash Converter).I put a white stripe on the rear tires and made a video of several runs. The rear tires do NOT spin or break loose...it just launches...and it pulls both front wheels about 7" off the ground for about 6 feet..perfect...and this is on a 3640 lb b-body coronet. Reduced my 60' time from the 1.65's to 1.45's. My car runs 10.50's at 126mph. 3640lb B-Body Coronet. 505" making about 675HP on the engine Dyno.
Comp Flat tappet cam, 12.2-1 Comp, INDY SEZ Std Port Heads, Hooker 1 7/8 headers with 3" collector. Edelbrock Victor Single Plane Intake with Super Sucker 4150 t0 4500 Adapter with a new 1050 Dominator. 4.30 Dana with spool.
 
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