Topic: Improving Traction

[Jeff73Mach1]

I would like to make some changes to get my car to hook up better.  Right now if I use anymore than about 1/2 throttle when letting the clutch out in first, I just light the rear tires up.

The current tires are BF Goodrich Radials 235-60-15 on 15x8 rims

My current thoughts are 

lower air pressure as much as possible but how low can I go?  26 pounds? less?

Go to wider tires.  How wide can I go without interference and what is the widest tire I can fir on an 8" rim  285's?

add Subframe connectors (don't expect this to help much, but it needs them)

Add under ride traction bars.  I've seen a set of plans to make some myself-anyone have experience with this?

I don't want to go to a custom rear suspension set up, but even when I get moving without spinning the tires, when I mash the throttle in first, I can  always expect wheel spin.  It is fun, but it doesn't do much for acceleration.

[ol dirty doug]

well first of all do you have a posi or lmited slip rear end?  and i run 17lbs psi in my tires on a 17 inch wheel, i imagine you can do the same.  also one little trick you can do is install an "airbag" above the passanger rear leaf spring. air it up a little at the track to get more traction on the passanger rear wheel, that is the first one to spin most of the time.  as for traction bars, those really only help if you hare wheel hop or spring wrap. if you have slicks and leaf springs i highlt recomend those. sub frame connectors are a great upgrade and will help with traction due to the twisting motion of the body, and puts more torque to the ground and not thru the body.

[Jeff73Mach1]

Thanks Doug

I have the Track Lok rear end (posi) and dropped back from 4.11 gears to 3.50 gears as I do drive on the interstate a little bit and the 4.11's were a bit excessive.

I currently do not have any wheel hop, so I am going to leave traction bars on the bottom of my list of things to try.

I found 275-60-15 BF Goodrich radials that match my current tires (except for size and I think I can run that width without a problem.  At $70.00 a piece they are cheap enough to give a try.

Since my rear end is 28 spline axles, I don't think I'll be running slicks anytime soon.  I suspect my horsepower and the centerforce dual friction clutch might make it possible to twist an axle running slicks.

Hopefully I'll get the car dyno'ed in January after finishing up an ignition upgrade and getting the timing and fuel mixture both dialed in. 

Bigger back tires should also drop my effective gear ratio down and besides

Muscle cars look cool with big fat tires in back!

[Soaring]

A lot of guys use drag radials on the rear.  They are not slicks, but stick to the pavement better than street tires.  Go around the water trough before entering the staging area. Also, do a burnout before the tree lights up.  17 lbs on the tires seems a bit too low to me, but if it works, it works.  I agree about the sub-frame connectors.  Also, a lot of guys try to get as much weight moved from the front of the car as possible, threfore, moving the battery to the trunk. 

[Jeff73Mach1]

Thought about moving the battery, but the fastback trunk is so small already that I am reluctant to do so.

ANyone have experience with tinman subframe connectors?

http://www.tinmanfabrication.com/index.cfm/page/ptype=results/category_id=60/home_id=59/mode=cat/cat60.htm

[Soaring]

To move the battery to the trunk, you have to completely level the floor of the trunk on a fastback.  Here is what it should look like when finished.

[Jeff73Mach1]

One of the issues with locating the battery in the trunk is that with the trap door and fold down seat, the trunk area is not sealed from the passenger compartment.  A proper battery box takes care of that, but the other issue is the spare tire mounts on the passenger side leaving only the driver side available unless I want to cut the hold down sheet metal piece away and remount it to the opposite side.  I really would prefer not to do that, and a battery and my 200 pounds of driver weight would really make the car a little lopsided and unfortunately it would be to the wrong side for traction purposes.

I suppose I could use a really light battery for the drag strip, but for the day to day street use, I want to improve traction as well.  20 pound tire pressures don't seem to me to be a good solution on the street, but maybe 22-24 pounds would be better.

Or I could just spray the tires with 3 M adhesive before driving LOL

[ol dirty doug]

dude i love the 3m idea!!!!!!!!!   i want to see a video when you do it!!!!!

[Soaring]

Why need a spare tire if your purpose is to move weight to the passenger side of the rear while dragging?  I hope you don't stop to change a flat during a drag race.     You don't need to be racing from light to light in the city anyway, so why worry about the weight on the fat butt driver's side?     What I have shown you is a way to move the battery to the passenger side in a fastback, and it has been done many times, but only if you are serious about drag racing.  For street use, this procedure is a costly and worthless waste of money.   The weitht of most batteries is about the same, so using a 4 lb. less weight battery during racing situations is folly.  If the weight of your body on the driver's side makes your car sag to the driver's side, then you have a lot more suspension issues than the weight of a battery. 
If you want more weight on the rear during drag racing situations, throw in a sack of sand on the passenger side.   

[Tim175]

When i raced my truck i used bags of cement in the bed, but after the first pass they made me get rid of them so i just spun the tires at the line for several seconds before i could move haha. But yes the 70s mustangs always had the traction issue. I have the same problem on mine but seeing as i don't race in on a regular basis and during street driving it seems to be ok i havent really tried to fix it.

[Jeff73Mach1]

Well I really don't expect to play at the drag strip more than a couple times a year so I'm leaving the battery as is.

My car does not sag, thank you very much, in fact it has 200# rear springs and they are fresh and the rear end is pretty stiff.

I do not intend to drag from light to light, but there are some places where I drive still that have almost zero traffic, and it is fun to be able to use the power that I built into the car.  Without traction, power is somewhat wasted.

Besides, you never know when society may collapse and the ability to accelerate from 0-60 in under 5 seconds may mean the difference between life and death.   Come to think of it I need a blower LOL

[Tim175]

I know what ya mean about the power being pointless with no traction haha. My buddy and i put a 383 stroker in his el camino and now its wasted power because he can't even move when he punches it. He just sits there spinning his tires haha. Blower would be a nice addition too

[Konrad]

Besides, you never know when society may collapse and the ability to accelerate from 0-60 in under 5 seconds may mean the difference between life and death.   Come to think of it I need a blower LOL

lol yes society may collapse!

don't just add a blower, add armour plating and a missile launcher too.

[Boss351Dude]

The problem is the BFG TA tires. Any tire with a soft compound is what you need. The 28 spline axles are just fine with slicks. If you worry about twist, increase the air pressure and dial in a bit of spin. Ran slicks on the street for years with an 8 inch. Raced it every Friday night at the track. Never any problems. This was in a 66 that ran 12.7@107 mph at 3400 feet altitude.  Drag radials or MT ET streets are the best choice for a street car. Try some Comp Engineering drag shocks at the back. 50/50 ratio.

[Jeff73Mach1]

Thanks!  That is good info.  I was looking at a set of street legal drag radials.  I'm still torn on the size issue though.  I have room for bigger tires and since I'll still do most of my driving on the street, I'm thinking of getting a second set of rear wheels for the Drag Radials.

Hopefully Tim 175 will tell me about the size of the monster meat on his 72 when he bought it.