I have a 66 vert with factory suspension wheels and 205 70 14 tires. I am unable to tell whether it is untouched but to the my untrained eye, it looks that way. The car appears to be well taken care of and I have no reason to believe it was customized/modified. I see no bent pieces and the steering appears to be tight and the rear wheels are tracking behind the front. I have not seen any sloppiness in the rubber or control arms but notice the front suspension is not very compliant compared to the rear (rear is bouncy and can really get the back end moving up and down wherreas the front end does not move more than 1 inch up and down). I have no experience with anything other than GM mid size muscle cars (coils front and rear). I bought the car to drive on road trips and do drive in a very spirited manner. Anything close to spirited in this car scares me. The car gets unsettled by potholes on highways or surface streets mostly when in a gentle turn. For instance, if I am in a gentle left corner on the highway, any potholes result in the back end slightly jumping to the right which I tend to not have to correct but this behavior unnerves me. In a gentle right hand turn, any pothole results in the back end jumping left. I do not notice any of this when tracking straight ahead.

I've read about bump steer. It appears that slight bump steer was in factory mustangs but was adjusted out. What I'm experiencing appears to be mild bump steer. I dont have alignment rack access but I did some crude checks with a lasar attached to the wheels to look for significant toe changes. It appears that when the suspension is unloaded that both sides toe in (I'd be surprised if it was 1/16 inch or greater). I could not really load the suspension but tried to rock the front end up and down, I noticed that both sides toe out upon compression (again, I doubt more than 1/16 of an inch or greater). I was looking for gross difference or toe change but didnt find anything. Both wheels were consistent. It may well be that my 71 442 does the same thing but I have never performed this test and do not know what is to be expected. Comments from the experts here...

I read more web articles on alignment. It appears that the factory called for positive camber and negative caster whereas modern/performance settings call for around 0.5-1.0 degree negative camber, 1.0-2.5 degrees negative caster and everyone agreeing to 1/8" toe in. I read a particular web article by someone that installed granada discs which apparantely really add bumpsteer. They complained that this car had become a city only car despite 3 alignments due to scary manners on the highway. After suggestions on numbers were made, a 4rth alignment achieved tracking straight as an arrow at 100mph. I dont recall them adding a bumsteer kit. I dont know that a bumpsteer kit would help me due to the toe behavior described above (bumpsteer kits would help for someone that had opposite toe behavior which necessitates lowering tie rod mounting points or some other mod that either lowers the vehicle or in some way alters the original geometry...suspension experts, please correct me as needed).

Does anyone have any thoughts? Is this the dreaded bump steer? My first priority is to get rid of this whatever it is before I look at sway bars, springs, shocks, shelby 1", etc. I would prefer to stay with factory suspension until this is worked out but have also entertained upgrading pieces such as the spring perches and the strut rods (I cant see how any of these would worsen the current situation). My plan is to find an alignment shop that deals with customs/rods and then tell them what to set camber/caster/toe...the theory being that these shops know bad suspension when they see it and have probably seen very unusual stuff and they are also likely to have heard of bump steer. I wonder if a good shop will tell me the current setting?

Any suggestions are welcome. I did not find anything specifically dealing with a factory suspension and also wanted to put enough description which presumably if I get good tips will help out the next guy...There is a plethora of aritcles for shelby drop, granada disc, cut coils, etc but I have not found anything dealing with a factory setup. Thanks.

Fred

 

Can't help you from a personal experience standpoint, but Mustang Monthly had an article about how to correct bumpsteer in Feb 2006 issue page 56...

Maybe you could provide cliff notes for those of us with attention deficit disorder...[sm=joke.gif]

 

The only thing I can see you didn't mention was whether or not you have power steering and a V8.

My first suggestion would be to take the car to a good alignment shop and have a complete inspection done. Stock suspension in good shape will steer pretty well. They still race with pretty much stock front end components (just stiffer springs and shocks).
Bump steer will cause the car to dart to which ever side gets compressed. Let's say you hit a speed bump with the right side only, the car would want to pull to the right as it hits the bump and the suspension compresses. If your strut rod bushings or lower control arm bushings are shot it will make it do the same thing to a lesser degree. Same goes if your idler arm bushings are shot, or your steer box is sloppy. If the suspension has not been modified, I doubt you have an issue with bumpsteer, unless your springs are really sagged out.

I've got a '66 vert 6 cylinder. I've done a lot of suspension work to it, front and rear. There is a poor write up on the web page in my signature. At least it shows what I've done.
The only rubber I have left in my front end is the two polyurethane sway bar bushings. The car handles incredibly well (I'm hitting just short of 1G lateral w/o pushing the car too hard). The newer alignment specs work better with radial tires, The patch of tire contacting the ground moves rearward more on radial tires than bias ply, so it really helps keep the car stable at speed. It needs even more caster with Rack and Pinion. I'm at 3.5 degrees caster with my rack setup to get a good return to center feel.
Front and rear suspension is another area that pays to really do your research. There are more different ways to go than you can imagine.

For a weekend cruiser that you want to keep fairly original, my recipe would be:
1" sway bar, cut the stock springs to drop car about 1" (or go up to about a 480# rate and remain at stock height with a 6 cylinder, or 580# stock height with a V8), lower the upper control arm mounting points 1" (ala the Klaus Arning/Shelby drop) this will drop the car about 1/4"-3/8". Roller spring perches, and KYB Gas-a-just front shocks (or Koni's if you've got the bucks).
V8 car w/o power steering, I'd do a 19:1 box and a quick steer kit. With P.S. just rebuild the box, valve and cylinder as needed, maybe revalve the pump relief to decrease pressure and flow. Either way add a roller bearing Idler arm.

Don't forget to inspect the rear end as well. Worn out spring bushings will also cause the car to float around on you.

Good luck,

 

Scott,

Thanks for the reply. I thought I covered everything...its a 66 V8 with power steering. I appreciate your comments on "what to check". Your weekend cruiser comments are spot on. Later down the line, I was thinking 620 springs and hipo leafs (had not thought about doing the drop but am reconsidering after your recomendations). I wish I could ride in something similar to know what it is like but will likely take the plunge any way and will go with the additional recommendations you had. Meanwhile, I'm gonna scour your web...

Fred

 

The down side to the stock power steering is that it takes a good 1/4" movement on the pitman arm to activate the valve lever, so you feel there is about a 1"-2" play at the top of the steering wheel (16:1 ratio). This can be lessened by going to a smaller steering wheel. Like an aftermarket wood or leather wheel, which also gives a slightly heavier feel (which is much needed in my opinion).
The key to make the stock system work well is to make sure everything is built to very tight tolerances, so that the play is limited as much as possible, and run the updated alignment specs.
Before buying new springs, measure the distance from the center of the wheel to the top center of the fender lip, it should be 13.5" if the springs haven't sagged. If they haven't I'd cut the stock springs to lower the car 1" and run either the Koni's or the Gas-a-just. Cutting the springs is free, and you'll keep the same shocks even if you go to a stiffer spring. Cutting the springs increases the spring rate as there is less coils to compress.
My experience with unibody convertibles is they need a slightly softer spring than a hardtop to keep the cowl shake down, and the body from twisting, that's why I'd recommend the 580s over the 620s. Convertibles are different animals when it comes to handling. I'd shy away from the status quo and think carefully, or be willing to try different combinations.

I wish there were more performance oriented convertible owners out there to share tips with. I've only seen one 1st Gen Mustang on the track that I thought worked well. Unfortunately I don't know who he is.

Are you anywhere around Northern California? If so, we could meet somewhere and you'd be welcome to drive my car. You'd just have to promise not to give me any crap about my poor little 6 cylinder engine.

Scott

 

I went through your web and immediately noticed your Lafayette frames and black plates (I really notice them these days since mine has black plates as well). I'm in Walnut Creek and am pretty excited to meet someone nearby.

One of the first things I looked at first was the "play" at the wheel. I was expecting something in a car this old with 100's of thousands of miles and then was gonna have someone help me wiggle the wheel till I found the source of the clearance (sorta deja vu...as a kid, I helped my dad with this issue his 46 ******...as I recall, 1/4 turn play which made for adventurous off road trips!). The wheels responded so well to steering wheel input I didnt go any further.

I will probably go with cutting my springs or find a source for the 580's (I'm short on those types of tools). I will measure the front as you suggested. I definately value experience and would rather not experiment with springs (too much trouble to remove and replace). As for the back, I am fairly certain the springs have sagged (I looked at details from your web for a reference and I'm definately sitting about an inch low in the back...it will look bad with 3 or 4 adults in my opinion). But, slight lowering of the front might make the back end not so noticeable.

I will go ahead and email you as I'm not sure anyone else is interested in this thread continuing... Thanks for your comments!

Fred