I am having problems with my alignment. I took it to the alignment shop and they said that the caster can not be adjusted anymore than it is because I have run out of adjustment. They said that my strut rods are too long. It has been lowered 2 inches by cutting a coil and everyone is blaming that for my problem but I have not heard anyone else complaining about the same problem. Has anyone else encountered this? My only guess is that the upper control arm might not be installed properly. Is there any way that the upper control arms might be on the wrong side. Or could it be the the control arm bar might not be adjusted properly so that it is centered?
Now it's been awhile since I've aligned one so bear with my old memory... If I remember correctly the upper arm mounts like the old mustangs. If I'm remembering correctly once I ran out of adjustment on the bottom cam for camber and strut rod adjustment I'd shim the upper control arms, I'd start with an 1/8 & 1/16 shim in THE FRONT upper control arm bolt. This added camber and caster to the car. This usually allowed me then to go back and adjust using the lower arm cam bolt and strut rod to fine tune. Now realize that your car is a NEGATIVE caster car. Most shops if they don't have specs for it expect it to be POSITIVE castered and then give up when they can't get it to move positive. I'd guess yours is in the -1 to -1.50 negative range factory. I always try to get the caster as positive as it will go on old cars to help them drive a little straighter and I always run a 5/16 to 7/16 more positive caster in the p***enger side wheel to make up for road crown.... ...
Sagging unibody would not be out of the question for a 63 year old vehicle . If your FE shop knows how alignment works , they should be able to get your car driving straight without wearing out your tires prematurely
Thanks I think all this information will be helpful. I will definitely ask if they are adjusting for negative or positive caster
It is possible that lowering the car has increased negative camber, they have then returned this to factory on the lower arm adjustment which has then meant that the strut rod can’t be shortened enough to compensate. I’d ask them what the actual readings are at the moment. A competent guy with a lathe can sort out more adjustment on your strut rods quite easily. Like Lostone says if you can get a reasonable amount of positive caster your car will drive in a much more modern way. Be careful if you’ve not got power steering as it will increase the effort required. I’ve got 4.5 deg caster, -0.5 camber and 0 toe on my Mercury and it goes down the road really nicely and has much improved turn in and directional stability. Slightly different method of adjustment as that’s all on the top arm.
So even if it is a negative caster car I should try to get as much positive caster out of it as I can?
I've got a 61, I ***ume it's the same???my print out sheet says caster should be -0.5 to 0.5 the car was at -3.8 left and -5.1 right when I took it in.... after alignment.. caster is at 1.3 both sides... so, question we're talking positive caster as leaning back??? to rear on top
I'm thinking I'd rather have a couple degrees positive....never once have I owned a car that steered and handled good with neg caster... and for sure now at hiway speeds... I don't think my strut rods are out of adjustment... meaning there's no more adjustment left.... we'll see...
I talked to the alignment shop today. It sounds like they only tried adjusting the caster by adjusting the strut rod instead of giving everything a thorough look over to make sure something else didn’t need adjusting or shimming. I think that they ***umed that an adjustable strut rod for a Thunderbird would be the easiest solution like it would be on other fords without realizing that is not an available part for this car. I am going to bring it back to them next week. He is also of the opinion that positive caster is a better option.
Positive CASTER is the inclination of the upper and lower ball joints. Think of it this way, standing and looking at your car from the side, looking at the front tire. Think of an imaginary line drawn from the bottom ball joint that goes up through the upper ball joint. Now if this line is straight up and down then it's 0 caster, as you lean the upper ball joint forward towards the front bumper it becomes NEGATIVE caster, if we move the line straight up and down again we are back at 0, then as we lean the top back it becomes POSITIVE caster. Now why does things change ? Why negative to Positive caster as car grew newer? Power steering! NEGATIVE caster is easier to turn with manual steering, start adding caster and it becomes harder to steer. So with the old heavy cars and parallel parking with manual steering the factory set up the suspension to have NEGATIVE caster. So in 1970 or so most cars started coming standard with power steering and you seen suspension design change with it designed with Positive caster and most went to the suspension going negative CAMBER when the front suspension was compressed, before this most cars went Positive CAMBER when compressed. So with the new designed suspensions built for Positive CASTER AND Negative CAMBER under compression and power steering we had cars that really drove and handled well for their time. To really see this in an extreme example drive a 69 firebird/camaro and push it hard, then get into a 70-1/2 firebird/Camero (there is no "70" models) and it's a night and day difference. The newer model will drive/handle circles around the older ones... ...
So I took the car back to the alignment shop today. It sounds like they were able to get it to drive straight by using shims on the upper control arms but he said that he had to adjust each side very differently than the other. He said that the pump or the gear box needs to be rebuilt. He said that when he started the car up that he could see the wheels twitch to on side and when it shuts off it will do it again. I did hear a crunching noise when turning the wheel this morning so I am sure something is wrong with the system
If it twitches then it's the power steering control valve. The cylinder that's screwed on to the end of the center link and connected to the steering gear. The crunching noise, which I hear alot of complaints about, is usually the wheels turned to lock and someone either pulling into or out of the driveway on uneven ground and the spindle stop locked against the stop on the lower arm and the noise is just the metal to metal contact as the suspension moves, no big deal totally natural. People never seem to notice it until A: they just had front end work done, B: just had it aligned, C: someone brings it to their attention.... ...
Positive caster- think a "Chopper" motorcycle. Negative caster- think front wheels on a grocery cart. Easy way to remember. We used to add length to the forks on our bicycles back as kids to make "choppers". I still remember how they rode- very stable- easy to ride no handed, but hard to turn when going slow.
Those old Birds were always a chore to align. The a-arm shims are big and never came out or went back in without a battle.
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