centering a manual steering rack

cwitt · cwitt's Garage

Hi all,

When I was installing turbo tie rods the other day, I couldn't help but notice that my original tie rods were about 1/4" different in length. My car drove nice and straight with the steering wheel centered, so I suspect that the wheels and the steering wheel were centered, but that the rack was actually off center from both of them.

The shorter of the two tie rods only has about 1/4" left on the adjustment threads before it's at minimum length. This not only bugs me, but I suspect that one ideally wants the pivoting parts of the tie rods equidistant from the steering arms on the struts for optimal steering.

(As a side, I did need to install the washers with the turbo tie rods, as the threads bottomed out in the rack without them. Both tie rods would certainly have a little more adjustment range with no washers or thinner washers.)

Does this logic make sense, and if so, what's the best procedure for centering a manual steering rack? I'm thinking it goes something like this:

loosen the steering shaft clamp
pull the boots off the rack
center the rack
while keeping the rack centered, center the steering wheel and tighten the clamp
lengthen the shorter tie rod by 1/8"
shorten the longer tie rod by 1/8"

I know this isn't going to leave me with perfect alignment, but I need to get it aligned anyway, since I just refreshed all bushings and tie rods.

Thanks!

steely · 08:04 PM

If your 85 is like my 87, there is a groove in the steering shaft that goes in the split clamp - and they have to line up. If I understood your proposed method, the groove and clamp may misalign and prevent the clamp bolt from insertion.

Short of stripping the rack and adjusting the pinion, I'd say pulling the steering wheel is your only option to get you close, and then you would need to make only minor changes using the TR ends.

Also, I think you need those big TTR washers.

Flieger · Flieger's Garage

If the car is aligned, then you do not have to worry about the pivots being in different places- different length arms. The adjustments are on the inside of the pivots, correct? So then the rack is just closer to one side than the other. It does not effect the steering as long as the threaded portions are short enough to be considered "rigid".

cwitt · cwitt's Garage

Quote:

Originally Posted by Flieger

If the car is aligned, then you do not have to worry about the pivots being in different places- different length arms. The adjustments are on the inside of the pivots, correct? So then the rack is just closer to one side than the other. It does not effect the steering as long as the threaded portions are short enough to be considered "rigid".

Nope - the adjustments are on the *outside* of the pivots.

Flieger · Flieger's Garage

OK, now I see what is going on. The procedure you described in the beginning would be adjusting the threads inboard of the pivots, the ones inside the boots. The ones that are asymmetrical right now are the ones connecting to the steering arms.

Yeah, I would do what you outlined, then get it to an alignment shop.

I suppose the thread pitch is the same on inner and outer? If so, then just count the turns, otherwise a DIY string alignment would be good enough.

wildcat077 · wildcat077's Garage

String alignments are a good reference point when you're replacing the tie rods,especially on vehicles where you replace both inner and outer tie rods ... EX , my Ford F150 ...
Had to replace my inner and outer rods four times since owning the truck and although there's a lifetime warranty on MOOG parts i didn't want to spring for an alingment each time and the string method was always spot on ...

Cheers !
phil

cwitt · cwitt's Garage

Quote:

Originally Posted by Flieger

OK, now I see what is going on. The procedure you described in the beginning would be adjusting the threads inboard of the pivots, the ones inside the boots. The ones that are asymmetrical right now are the ones connecting to the steering arms.

Yeah, I would do what you outlined, then get it to an alignment shop.

I suppose the thread pitch is the same on inner and outer? If so, then just count the turns, otherwise a DIY string alignment would be good enough.

There's only one set of adjusting threads on each turbo tie rod -- the inner portion of the rod just pivots in the ball/socket joint. The outer section stays still (once it's connected to the strut steering arm), and a jam nut fixes the adjustment in place.

And yes, nothing inside the boots would be adjusted -- I just need to remove the boots to see if the rack itself is centered.

KTL · 03-22-2011, 10:24 AM

Instead of disconnecting the steering shaft at the u-joint, you can disconnect the steering rack coupler flange and reindex it on the splines of the pinion. That's what I did when I regreased my rack years ago. See this exploded view diagram from a Clymer manual I scanned back then

http://forums.pelicanparts.com/porsche-911-technical-forum/85404-steering-rack-rebuild-procedure.html

Between the splines on the pinion and the splines on the upper shaft at the steering wheel, there's enough fine adjustment to get the rack reasonably centered. The fine tuning at the tie rods finishes it off.

In all honesty, what's the big deal if the rack is not precisely on-center? Is there really a noticeable dynamic effect? I understand that your steering wheel rotation from center to left or right lock will not be the same, but so what. Who applies that much steering input to turn these cars? The ratio is quick enough that rarely is more than one rotation needed, even in the tightest of spaces.