Hello All,

I'm installing a rebuilt rack and need to know the best way to tell if it is centered. My theory is measure from the back edge of the boot, I'm call the back edge the large end that is fixed to the rack. Measure from there to the end of the tie rod, when those are equal that should be centered. Then make whatever adjustment is needed to get the pinion flat to the point it needs to be. Does this sound reasonable?

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Bruce S. near D.C.

Uncle Art B. (near Baltimore) uses a method by which he aligns the wheels to the straight line parallel to the rocker panels.

It is a start.

If you look at the rack, it is not centered at the rack end where the large end inner tie rod boot secures and that distance to the, say, outer tie rod.

You would be best served by biting the wallet and getting a proper steering thrust alignment from your local trusty tire store that is alignment rack equipped.

cheers,

dud.

"Uncle Art B. (near Baltimore) uses a method by which he aligns the wheels to the straight line parallel to the rocker panels."

Need to use the rear-wheel-parallel-string method to check against the rocker and see if the rearend is perpendicular to the rocker first....most times they aren't. And if they're not - alignment should be relative to the rearend, not the rockers.

Just did this today on mine. I measured the mounting holes - on mine almost 12" exactly between mounting holes. Center of the rack is halfway between those. So I measured 6" from driver's side rack mounting holes and marked the center of the rack. I then turned the pinion until measurement from the center of the rack to each tie rod end was the same (right around 23.25" as I recall). Once the rack was centered, I centered the steering wheel using a bungee wrapped around the seat slide bar.

Steering wheel centered, rack centered - then set up a string on jackstands parallel to back wheel. Use that to set toe. I put it at zero -- I'll recheck/re-adjust after I've driven it a bit.

I be this is a lot harder on the 240 with the rear track narrower than the front.

"then set up a string on jackstands parallel to back wheel. Use that to set toe. I put it at zero -- I'll recheck/re-adjust after I've driven it a bit."

For race cars we set FWD cars a little negative and RWD at about zero toe. For the street, if everything else is even close to factory, I a pretty sure you will want a little positive toe or the car will be to "darty".

"I bet this is a lot harder...." ? Not at all - just means once you get your string (I use very fine black sewing thread) set up parallel to the back wheel, the measurements to the front wheel rim are a bit shorter than those to the rear wheel rim. It's a bit more complex with IRS -- you have to know the track difference between the front and rear. You measure to the center of the rear hub, and then must add/subtract the half the difference in track to set the distance to center of the front hub. That gives you a parallel string to measure front AND rear toes against.

Forces acting on the front tire as the car rolls down the road tend to force a car to go toe-out. The faster you're moving, the higher the forces are. And the softer the front suspension bushes are, the easier it is for the front wheels to be forced into more of a toe-out condition. Typically, it takes a bit of static toe-in for the car to achieve a bit of toe-out when cruising down the road

I'm running much stiffer than stock poly bushes in the control arms, and no rubber at all in the coil-over struts, so I don't get a whole lot of rolling toe-out. When I aligned it last, I set toe at 1mm-2mm toe-in each side. And that seems to work great. Perfectly stable at cruise. No 'dartiness' at all.

Setting it at zero was just to allow a low speed test drive. I did it with front end of the car about 6" in the air, supported under the control arms - so the suspension isn't perfectly at ride height. If all is well with no leaks/noises, I'll restring it and set it back at 1mm-2mm toe-in with all 4 tires on the ground.

BTW, you can make your own swivel plates to go under the tires to allow adjustment of toe. 12"x12" VCT floor tiles from Home Depot (about 75 cents a piece) with a bit of table salt sprinkled between then. They're only 1/8" thick - put 2 or 3 under the front wheels with salt sprinkled between them. The salt crystals act like little ball bearings and allow you to adjust toe without trying to overcome the friction of the tire on the garage floor. They're also great for leveling up the car when you're setting caster/camber or doing corner weighting.

"BTW, you can make your own swivel plates to go under the tires to allow adjustment of toe. 12"x12" VCT floor tiles from Home Depot (about 75 cents a piece) with a bit of table salt sprinkled between then. "

We use masonite and baby powder...effect is the same. We have a "Toe bar" that we use for the race cars but for street cars I am lazy enough to pay for the laser alignment...especially when the locals offer lifetime checks and adjustments.

I suppose my issue is that I just don't trust 'em with the car. And I'm good for lifetime checks/adjustments as well. ;)

Read the part about "lazy". It is not so much laziness as too many other things going on. I needed to get the winter tires on and having to replace the rack to do it (see earlier threads about truly frozen rod ends)...just took the easy way out.

On my truck it is more about the need to have it up on the rack because of the archaic steering system (recirculating ball...really!) and the shear size of things makes even a 1/2" breaker (with 3' cheater) and 3# hammer seem inadequate.

Thanks for the string tip, I'll have to try that.
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Bruce S. near D.C.

you're over thinking it.

as you'll see when you actually have the new rack in your hands and old one is being unbolted there is really only one way to install it with minimal slop to either side.

I think you misunderstood my question. I'm referring to the side to side travel of the rack in relation to the pinion position. In other words having the rack centered in its path of travel, before I attach the wheels, so you don't wind up with a 1/4 turn to the left and 3 turns to the right. Get it?
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Bruce S. near D.C.

Turn it all the way clockwise, then all the way counter-clockwise, counting the turns. Then turn it clockwise half the number of turns and it should be near the centre. When you connect the u-joint coupling, I think there's a flat between the splines where the bolt goes, so you just connect it the way it fits.
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1992 745, >500k km

Thanks,

Doing it the way you suggest is going to be the only true way to tell.
I thought there would be some practical way to measure it but no such luck. I now have the old and new racks side by side and they are both centered differently. So I'm about to get busy turning and counting, once again thanks.
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Bruce S. near D.C.

One word of caution. Keep the steering wheel centred and secured with a bungee cord or something. Without the rack connected, there are no stops and if the wheel is out of position by a turn, then you can strain and damage the clock spring at full lock.
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1992 745, >500k km

OK, maybe I am understanding...did you pull the old rack already? If not:

Center the wheel
Put the seatbelt through the steering wheel
Break the tie rod ends free
remove the old rack
install the new
Look inside and make sure everything did not get all turned to one side or the other
Install both tie rod ends

I do not want to say it is idiot proof but assuming the splines are keyed on the u-joint on a 240 as they are on the 7/9 seiries, this works and your steering wheel will be centered a well as it was before the replacement.