Unlimited DFW Adjustment

[Old Geeezer]

While tuning my Unlimited for next Saturday I ran into a strange problem. I can start with about 2" of drift on my 6ft. tuning board and increase it about a inch each time run the car down the board until I get to about 5" of drift then when I try to tune 5 1/2" or 6' of steer the car start drifting straight and as I continue to turn the axle counter clockwise it drifts to about 4" of drift then jumps to about 8 or 9 inches and is tunable to about 14 inches.

The problem is it won't tune in the area I need 6 thru 8 inches of drift. Just by shear accident it will tune some where close to 7" which is close but not fast enough to be in the hunt. I spent 5 hours trying to get it close to 7" of drift today.

Any one have any ideas on what the problem is or have seen the same symptoms.

 

[DerbyDad4Hire]

Are you rotating it into a negative cant? You don't have any drilled cant on the FDW do you?

 

[Old Geeezer]

Positive cant and No drilled cant. Really strange you can watch the wheel visually point in on the front side of wheel (9 o'clock position) go thru straight (12 o"clock) and then point in on the rear side of wheel (3 o"clock) while turning axle with the car in your hand. All while the wheel has a positive canted. If you start with the car going straight down the board and then adjusting slightly each time for a about a half inch more steer each time down the board until get to about 5 1/2" all of a sudden it starts running straight down board again (you can see the positive cant) then comes back out of it as you keep turning at about 8 or 9 inches. When you do get close to 7 inches of drift you can breath on it and it changes about 2 or 3 inches to about 10 or 11 inches of drift. The com is a little over 1/2"

Will a bad (bent) axle cause this?

 

[DerbyDad4Hire]

Don't think it is the bend. Rear end issue? You shouldn't need that much steer anyway...

 

[renegade]

It may be the tuning board. I have that problem with mine if I put a lot of steer on an unlimited the front will slide down the tuning board and not turn.

 

[Quicktimederby]

Great minds think alike, that is what I was thinking. I would tune that one on the track.

It may be the tuning board. I have that problem with mine if I put a lot of steer on an unlimited the front will slide down the tuning board and not turn.

 

[quadad]

Might you be too aggressive on the COMh ? Would you consider shifting some weight forward and going with less steer ? My Unlimiteds don't have near that much drift.

 

[OPARENNEN]

Take it from me. You don't want the drift to be over 3 inches over 8 feet for unlimited. Forget the COM, just start at 3 inches and work down, not up. Are you able to time your car after each test? My record holding car has a drift of 1.5 inches, but I have two other unlimiteds, and each has a different drift. HOWEVER, be sure the rear wheels are ABSOLUTELY parallel to the body and track. Measure with a caliper, not a ruler. When measuring, there should be no wheel gap (to eliminate the slight wobble while measuring). Set the gap after you are sure the rear wheels are in line. The unlimited axles are often not 100% true.

While tuning my Unlimited for next Saturday I ran into a strange problem. I can start with about 2" of drift on my 6ft. tuning board and increase it about a inch each time run the car down the board until I get to about 5" of drift then when I try to tune 5 1/2" or 6' of steer the car start drifting straight and as I continue to turn the axle counter clockwise it drifts to about 4" of drift then jumps to about 8 or 9 inches and is tunable to about 14 inches.

The problem is it won't tune in the area I need 6 thru 8 inches of drift. Just by shear accident it will tune some where close to 7" which is close but not fast enough to be in the hunt. I spent 5 hours trying to get it close to 7" of drift today.

Any one have any ideas on what the problem is or have seen the same symptoms.