4-Link Question

The 4-Link bars on my car are adjusted a little over 1/4" shorter on the drivers side than on the passenger side. Also, the rear axle is not centered to the chassis/body. Distance from the axle face to the chassis centerline is close to 3/8" longer on the drivers side than the passenger side.
This is how it was set-up when I bought it. I have had it out to the track a couple times to workout bugs & have made two semi-hard runs. It drove OK. After these two runs I noticed the drivers side rear tire was rubbing on the body. I was measuring things before changing 4-Link settings to get a little more clearance on the drivers side.
Should The 4-Link bars be equal length & rear axle be centered?

Probably....Are you saying both upper and lower bars on the dr side are longer than the pass side bars? Does it have a wishbone in it or a diagonal link? My guess is it was someones attempt to preload the car?!? Do yourself a favor and start over. Get the rear squared and get it on some scales.

I only measured the lower bars. It has a wishbone. The wishbone arm rod-end on the drivers side is screwed all the way in.

string line it

Does the car launch straight now?? If so it may have ben adjusted as it is to make it go straight.

If it were me I would get the rear squared, possible make sure the housing is not bent as well and start over with scales. It SHOULD be in the car square but you never know how it was built. Possibly it is where it is to make it go straight? But I would want to star over. Square the rear and have Zero preload on the bars. Set the pinion angle and work from there.

Rather than type it all out here is a link to some 4 link basics. It is a good reference point for someone new to them.

http://www.racingjunk.com/forums/showthread.php?17130-4-Link-Basics-Theory-amp-Help-Instructions

Is this a back half car or full tube chassis...
make sure the front bar is square in the car then
start from the beginning.. if the other guy set it
up like that to drive straight on the launch he did
it all wrong and if it drives straight now.. something
is built wrong

Thanks for the replies.
PlyCuda - I did the plum-bob/string layout to get these measurements.
Al_A - Thanks for the link. I saw that google-ing around but did not read it all. I will now.
Mr. P - It is a back half car. I have only made a couple trans-brake launches at part throttle & eased on the gas pedal. It did go straight.

did you try a string line down each side of the car get it straight with the rear wheels and see how it measures to the front wheels. that can tell you a lot. if the rears in crooked or if the rear is bent. but you need to make sure the toe is right first.

Since its a back half car I would check to make
sure the front cross bar is square in the car

I did not check from the front wheels. just got centerline points from the front chassis and at the crossmember for the 4-link. Laid a string out on the floor for the centerline and took rear axle measurements from there. I did not measure from opposite corners but I will now to see if the whole thing is square.

FIRST thing to do is make sure the 4 link crossmember is square in the car. Does no good to square the rear to the chassis, if chassis isn't under the car square.

Assuming the brackets are square, placed on chassis and housing correctly.........meaning holes are same distance from housing centerline on both sides, clocked equally and brackets right on chassis, then you start squaring. First you make both bottom bars the same length and hang the housing and center it in wheel opening. Put upper left bar on and use this bar to set pinion angle. Then center housing from side to side under body and install wishbone. Upper right bar is last and with car on ground or platforms under tires, driver weight in seat, will install and be loose(no bind to get bolts in). The car is now square and has no preload. This is where you start. If it wants to go one way or another at launch, THEN you add positive or negative preload with upper right bar.

Thanks for the info.
Looks like I'll be measuring & squaring up this thing this weekend.

I took Roy Hills 4link class almost 20 years ago and the procedure they taught was exactly the same as Monte explained. The Haas chassis they used had reference points built into it to measure the axle location from

Yep, check the chassis and the brackets. I have had to make bars different C-C lengths, had driveshafts not run exactly parallel with the chassis centerline, fool around with housing locators, etc., because chassis or housing brackets were on wrong, body panels were not right, pinion C/L location in the housing was wrong or whatever. All to get the housing square and straight to the centerline of a car that the owner didn't want to cut apart and make right. Some people just can't read a tape measure and a level.

Get the car up and level on a clean floor and start measuring and stringlining or lasering. Time consuming, but the alternative is to just center the tires between the fenders, get the housing squared close by stringlining the sidewalls forward and run it. Not what I would recommend

I got it sorted out. Stringlined the chassis. All the points looked correct. Starting measurement pic attached. I positioned the rear axle like Monte said. I think the whole problem was a misadjusted wishbone. It took a while to get it adjusted so that the bolts to the rear axle brackets would line up. I think whoever did this last moved the rear axle to fit the wishbone rather than adjust the wishbone to fit the axle position.
Thanks.