Just finishing up my 4th gen rearend swap. Anyone know how to properly center and align the rearend. Is this something that can be done at home, or do I need to take it to a shop?

 

the adjustable panhard bar that i see you have should have enough adjustment to get it on center...i dont have one but i know the car has to be supported in the air and the suspension needs to hang...so pretty much you cant have the jacks on the rear axles to hold it up lol....if you have SFC you can just support the rear from the back of those

 

i assume you have adjustable control arms and panhard bar?

You want to adjust them with the suspension loaded, dont let the suspension hang, it will be a disaster. Put a straight edge across the wheel up to the quarter panel lip, measure both sides and adjust until its centered. As for front to back, center the axle in the wheel well.

 

haha oooppss.....i knew what i ment but i typed the EXACT opposite...thank you for fixing that one lol

 

So basically I'd unbolt the LCAs and Panhard bar and rest the rearend on jack stands before bolting everything up. I'll try this and see how it works.

 

To recenter left to right - just adjust the adj panhard bar - no jacking required - just turn it! It's amazingly easy, you could almost do it by hand!

 

if its a single adjustable bar, you cant do that.

 

no no no, jack up the axle buy the center section, leaving the car in that position, or you can put jackstands under the axle and remove the jack. You just want to make sure the suspension is loaded, if it isnt, your adjustments will move once it is. Adjust the panhard bar for side to side. If its a single adjustable, measure both sides, then unbolt the rod end side, adjust is accordingly, re-attach and repeat.

LCA's, measure the location of the wheel in the well. Unbolt the adjustable side of the LCA on one side of the car, and adjust it accordingly. Re-attach and re-measure. Keep track of how many times you rotated the adjuster. Once its right, unbolt the adjustable side on the other side of the car, turn the adjuster the same amount of turns as you did the previous side and re-attach. This way both LCA's are the same length when you are done.

Whatever you do , dont remove both LCA's at the same time. The axle will move and it will be hard to re-attach them, or worst case, the axle could come out of the car, the LCA's are what hold the rear in the car. Without them, the axle has no stability and can fall forward or rearward, or if the car is supported by the axle, the body would move away from the axle and you could cause serious damage and even hurt/kill yourself depending on where you are when it happens

 

i do it the same way, aswell as centering the axle, then i always do some tests. i like to burn the tires out of the hole both on dry and wet surfaces. if the car keeps pushing straight your good if not you may need to tweak your panhard or control arms, afte a few times of doing it i can tell if its the panhard being of center or the control arms throwing off the thrust angle, it usually take me a little while to dial it in, took it to an alignment shop once and the thrust angle was off less than 1 degree and everthing else was good and this was after swapping in LCA relocation brackets panhard relocation on both side and and the adjustable parts on both sides. and 2-3 hours of dialing it in,


if the panhard isn't centered you will feel the rear tring to come around when you're spinning the tires, if the control arms are off you will leave the line sideways but keep going straight, but then again it could be the other way around it been a year or so since i played with it

 

Center and align it to what? The chassis? Or do it the correct way and align it to the front suspension since the front is not adjustable?

This is very complicated- i would HIGHLY recommend just spending the $100 and have a 4 wheel alignment done on a flat sysmetric alignment rack with computer analysis.

Wow. this will take a real novel- it is basically chassis setup 101. you will need a perfectly flat section of concrete to work on (for a race car, I mean "perfectly flat" because scales would also be involved but I would do a street car backwards from a racecar because the front is not adjustable- racecarshave adjustable front a-arms and generally coilovers.)

The car now has to be jacked up and the suspension loaded to normal ride heights staticly but off the ground all four evenly.

Wheels need to be pointed straight, steering wheel needs to be centered- if this is off? check position of pitman arm and clocking of steering wheel on hub- if pitman is straight and wheel is straight, BUT tires are turned one way dramatically- we have a problem will someone originally assembling something wrong- we will not deal with this and just assume it is very close to correct(does not have to be prefect right now, we will get back to --------

you know what, Like I said before, this wil take a major novel and every car faces its own problem to try and list everything.......Take it to an alignment shop for a $100 4 wheel alignment.

On a garage floor it involves plumb bobs and tape measures squaring 3(2)x4(2)=5(5) and then diagonals multiple times with markings on the floor all being dead accurate to the 1/32" minimum. It takes me about 6 hours to disasemble and reassemble a complete race car chassis like this, check bump steer through suspension travel, set corner weights and check Ackerman on toeplates. They can do ALL of this for you on a good 4 wheel alignment rack in about two hours without the scaling part or stting chassis heights (since a street car for the most part is fixed in position on these factors without technician adjustments)

Dean

ps- If your track width is not parallel front and rear the car will not handle optimum. you can and most probably do dogleg very slightly and have thrust steer anyways due to deflection bushings and or improper alignment with the front suspension/wheels. I can not possibly write down everything here for people to read this and try to do their own cars- there is so much hidden for people to know and learn to get this as good a a simple $100 alignment would do. Most technicians only learn to run the machinery and do not even know what to look for mechanically- the computer alignment machines now days pretty much tell them what to do.

to do this yourself in a garage floor you will have to go back and forth stting the back then the front, then the back then the front again many times till you have the chassis squared not only to the suspension, but to the body so wheels do not rub fenders and sit underneath it sysmetrical you hope (I say that becasue the car could be bent from a prior accident or such)