Front end alignment tools

**Jim K.** · May 20, 2004, 09:04 PM

Re: Front end alignment tools

Forgot to add the part # to the Aamco tool #7825 Also can anyone point me in the direction of some manuals for either of these??? Thanks again!!! Jim

**Terry M.** · May 20, 2004, 10:14 PM

Re: Front end alignment tools

Jim,
We may have something around school, but school just let out an I am in New Jersey. Is the Aamco tool a magnet device that mounts to the center of the drum by the bearing?

**Jim K.** · May 21, 2004, 06:20 AM

Re: Front end alignment tools

Both tools have two adjustable sliding forks (for lack of a better trem). I would assume the top one is the one with one prong, the bottom has two. The ends of the prongs ate notched to seat on the edge of the rim. My guess is you have to set them tightly to keep them on the wheel???

**Terry M.** · May 21, 2004, 10:32 PM

Re: Front end alignment tools

Jim, it will have to wait until I get back to school and can look at the catalogs we have to see if anything fits. Maybe someone else can help in the mean time.

**Chuck S.** · May 22, 2004, 12:38 PM

Re: Front end alignment tools

Jim, I don't know how the new front end machines are, but in the sixties, some of them consisted of a low platform that the car was driven onto. The front wheels rested on circular plates built into the platform that allowed the front wheels to be turned in position.

The tools you are describing sound like the measurement heads that clamped onto the front wheel as you described. I believe this measuring head had spirit levels built into the tool which allowed the operator to read the camber and caster. As you said, camber measurement is pretty straight forward, but I believe the wheel had to be turned on the plate for the castor to be measured. Castor would be the same as "king pin inclination" wouldn't it?

**Terry M.** · May 22, 2004, 05:08 PM

Re: Front end alignment tools

"Castor would be the same as "king pin inclination" wouldn't it?"
Yes Chuck, I believe it is the same thing.

Even modern computerized machines have the turntables to allow easy rotation of the front wheels. Caster is measured by turning the wheels a specified number of degrees (10 or 20, depending on the manufacture of the machine) in each direction. Camber is measured at each position and in modern machines the computer calculates the caster from those readings. The older machines worked with light beams and mirrors, and while I learned on such a machine, I am not sure how it determined caster -- except the same "caster swing" had to be performed.

I have seen an AAmco tool that clamps to the end of the front spindle with a strong magnet. It has a bubble level on it, and also includes an eccentric plate that rotates to level the bubble. By measuring the degrees of plate rotation required to level the bubble one can determine the camber of the spindle. This tool also requires turntables and a "caster swing" to determine caster. I haven't used this tool since my shop classroom days, so I am not sure how caster is calculated from the readings taken at the right and left wheels turned position, but I am relatively sure we have a book on this tool at school. This will give me something to do next week.

**Craig S.** · May 22, 2004, 09:37 PM

Re: Front end alignment tools

Terry - I just had my 81 Chevy C20 pickup in for alignment, it ended up with new to A-arm bushing shafts in the process, I didn't feel like all the heavy spring work at the time. The alignment feels great, it tracks smooth and straight, and the new tires seem to be wearing evenly so far as far as the little nibs from the molding process (31.x10.5 X 16.5 BFG T/A Wrangler AT KO). My question is, the steering centering is off slightly, for the wheel crossmember to be straight the wheel needs to move to CCW left about 10 degrees of rotation. I know I can take it back, but would it still be spot on if I carefully move each tie rod to shift the rotation slightly as long as I am careful to move them eqivalent amounts? The rods are on the front side of the A-arms, not behind as on vettes. Which way would I turn them to move the wheel CCW...and would each side rotate the same way? This is probably obvious when I get under and look at the threaded tie ends to see which are RH and which are LH, I realize I am basicall keeping the overall length of the compostie shaft the same to keep toe identical, but shifing the relative position of the steering arm mount point.......thx, Craig

**Jim K.** · May 23, 2004, 09:16 PM

Re: Front end alignment tools

Thanks Terry & Chuck! I will make a stop at a local "friendly" front end shop that knows about C1's (my local solid axle mentor recommended one nearby). I just hate to give up without figuring it out, logic tells me that here has to be some starting point that s easily defined, I'm thinking you measure from lock to lock and do something with the swing in camber??? When I get it I'll post the board. Thanks for the help, oh yea, I'm told that the king pin inclination is adjusted by shimming the entire cross member, I may just leave that part alone!!!

**Terry M.** · May 24, 2004, 08:58 AM

Re: Front end alignment tools

Craig,
"I know I can take it back, but would it still be spot on if I carefully move each tie rod to shift the rotation slightly as long as I am careful to move them equivalent amounts?"
Yes, the steering wheel can be centered this way....if you can move each tie rod end equal amounts. This could be more difficult than you think. Small incremental rotation can make more change in the toe adjustment than you want. Toe will wear the tires more rapidly than any other adjustment. Why not take it back? Centering the wheel is part of the alignment process that should have been done by the alignment tech. Make him do his job. His next customer will thank you.
"Which way would I turn them to move the wheel CCW...and would each side rotate the same way?"
I'm not sure which way to turn the tie rod links, and would have to look myself. The position of the steering box will also be a factor...look at the threads to figure out which way to go. If the tie rods have never been replaced, or are properly reinstalled, the tie rod links should need adjusting in opposite directions. One needs to be shorter and the other longer in order to center the wheel.
I would take the truck back and make them do the job right. The chances of you getting it right without the alignment measuring tools are low, and once you mess with it they will, rightly, not stand behind their work.

**Chuck S.** · May 24, 2004, 02:19 PM

Re: Front end alignment tools

An old timer once explained to me that he put a little bit of adjustment in the steering linkage to permit the steering wheel to be centered when you are driving straight on a paved road.

A paved road surface typically has a slight crown which means you have to steer ever so slightly into that "crown" to keep the car from running off the road...it's kind of like steering an airplane into a cross wind to hold your course. If you have the steering wheel centered on flat and level ground, say an alignment machine, you will have to turn the wheel just slightly to the left to keep the vehicle going straight down a paved road. He adjusted the tie rods so that you were actually steering very slightly into the center of a typical paved road when the steering wheel was centered.

Craig, 60s vintage Chevys had an index line on the steering gear shaft that indicated "high center"(?) in the steering gear travel. Your chassis service manual will show this mark in photographs. The steering wheel should be centered when this mark is visible exactly at the 12 o'clock position; then if the technician is savvy, a little bit more adjustment in the tie rods for it to be centered driving on the road surface. Toe remains the same.

Front end alignment tools

Front end alignment tools

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Debug Information