I have a umi adjustable torque arm and bmr lcarbs. first time out I didn think the car was planting the back tires as hard as it should. I was running 8 psi in my slicks and had some tire spin off the line. I put the control arms in the bottom hole on the brackets and moved the front of the torque arm up a hole. umi guy suggested this. this week at the track I think it was hittin them to hard causing the rear end to unload and really spin. so which adjustment would be better to change back?

 

you need to find pinion angle. I believe it should be set between -1* and -3*.

 

what tires? 8psi is WAY too low for any tires on the market today that might be used in a stock wheel well. how old are said tires?

torque arm height adjustment should do nothing in theory as that plane is not involved in IC on torque arm cars. IC is found where the plane of the lca's intersects the *vertical* plane of the front torque arm mount. (ie: perpendicular to the ground) i'm sure the lca's being in the lowest hole has them hitting the tires way too dang hard also.

but seriously, details on the tires, ie: manufacturer, construction, size, and age first man. typically bias plys will want 12-14 psi, radials will want 18-22 psi.

 

the tires are mickey Thompson et drag slicks. 28x10.50 on the size. the lcarbs only have two holes and I figured I would try the bottom. I thought by moving the front of the front of the torque arm up it would move the ic up. the tires look to be maybe 4 or 5 years old. they were on the car when I bought it and I have had it for two years and only had it out twice.

 

buy new tires, yours are dried out. i only use my tires for 1 season typially, though i know those who will go 2. also put 12-14 psi in them, they will cup with 8 psi. when you get new ones, be sure to get the stiff wall version. the m/t 3055S would work perfect for your car. put the lca to the middle setting and put torque arm back to where it was.

 

the lcarbs only have two settings. i will set everything back to where it was. my converter that i just had built for the car is to loose so its coming out tomorrow and while i have it on the rack i will change my stuff back.

 

as said, you need to get tires. my 28x10.5 hoosiers would hook no matter what at 12psi. lca's can probably run in the next to bottom hole unless you are lowered. front hole on the torque arm wouldnt change much, i wouldnt think.
after each change you need to check the pinion angle and make sure its still 2-3 degrees. and dont just measure the angle on the rearend- you need to compare it to the driveshaft and put them 2-3 degrees in relation to one another.

 

Alright when I get it back together I will add tires to my list. I always check pinion angle when I get it off the rack. Thanks for the help

 

Rule of thumb for tire pressure. Approximately 1 PSI per second ET. A 12 second car should run well with 12 PSI in the tires. Increase tire pressure until the 60' times slow down.

My 32x14 slicks run 9.5 PSI.

Just because the slicks still have rubber left on them doesn't mean they're any good. The rubber will dry out and won't get sticky enough after a burnout. Even a track with lots of prep will still get tire spin.

 

that's a terrible rule of thumb. my car runs mid 10's and runs better at 13psi. where is this rule of thumb coming from? tire pressure has much more to do with size, rim width, and weight of the car. your big tires probably do like to be in single digits. small tires, it don't work that way.

 

there are 3 settings. stock, middle, and bottom

 

i run m/t 3055S 28x10.5 and found they like 13-14psi for my application. been a best of 1.36 60ft.

 

thanks for all the help guys. I will try that whenever I get the converter back. the car went 12.44 the first night out and I know it has a lot more. I mean I lifted the throttle two or three times. I went thru the 1/8 at 88mph and went thru the traps at 88 mph. thanks again

 

yup, lots more in her! keep us posted