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Unks37 11-29-2012 09:00 PM

37 Chev with Mustang II Alignment Question
I recently bought a 37 Chev 4 dr sedan with Mustang II front suspension and 4 bar coil over narrowed Ford 9" in the rear. Previous Owner said it had just been aligned, but Camber looked positive on one side and negative on the other side. Took it to a good alignment shop and it was way off all around. They were able to set up front end and rear all except getting positive Caster on the front. Currently at -3.2 on left and -3.5 degrees on right. The upper A arms are hitting frame on rear of arm preventing getting positive Caster. In driving it it seems to drive OK. I read one post about rake also affecting caster settings. With 29x18.5.15's on the rear it has a bit of a rake. I know it is possible to add adjustable upper arms, but what are problems for this amount of negative Caster? Your kind opinions would be appreciated!

timothale 11-30-2012 09:07 AM

welded wrong ?
When a suspension swap is done the frame should have been set at the planned ride height and angle that results from the tire sizes used. Castor angle has to work with King pin angle (a line thru the centerline of the ball joints) and the anti dive angle . When you turn the combination of those angle produces a chassis lift. different for each side. with the wrong castor angles, the chass is lift on the front corners is the opposite of the original intended design It can drive just fine straight ahead, but Might get to be a handfull on bumpy roads or when braking. With the anti dive angle, the front suspension adds castor when the front end comes down during braking. the goal is to have the effective castor the same. when the front end comes down the frame comes down reducing the castor angle , BUT the upper ball joints moves back because of the anti dive angle, adding positive castor back in. another question is how does it handle on fast hard corners ? does it want to over steer- or understeer or want to get away from you ? changing front to rear spring balance can help correct over-under steer ? an old friend is the retired head of Ford Racing, has written a lot of suspension design stuff on the Club Cobra Forums. just search bruce cambern's posts or #3170 ( His original Cobra number). HE smoked the 2009 optima With his much modified Cobra, won 3 Firsts and one second in the competition

timothale 11-30-2012 09:20 AM

Mustang II attachment
The original mustang II crosmembers are serrated at the upper A arm bolt areas and the mating parts also were serrated to minimize movement when hitting potholes. Most after market kits do not deform the metal to match the original design, and things can change, It is very important the the A arm bolts be retorqued after an alignment.

MARTINSR 11-30-2012 10:26 AM

What are the rest of the specs? Many alignment places are really not very good at this stuff, if it isn't in the computer they don't have a clue. I am asking because I have to wonder could the camber be lessened to give you the caster? Could a better happy medium be found in other words.

Do you have photos of the suspension? How about the locator/strut bar, does it have one (some Mustang II front ends are modeled after the original car with them some aren't) or does it have a full A arm that eliminates it? That bar can be adjusted to change caster if it has one.

Does it have adjustable lower control arms?

I am amazed at how some "pro" alignment guys don't see where adjustments can be made when it's not in the computer! We have an alignment system at work but have to farm out the alignments once in a while when the rack is tied up or we simply have too many to do. We have a very well known shop near by. It has happened a couple different times when we are told it won't align, sorry there are bent components. I go over there and have to show them where some point is adjustable that they didn't even see! I was told "Hmmmm, it didn't tell me you could adjust that" like I'm making it up or somehting. :rolleyes:

The guy may be looking at something very simple but not seeing the forest for the trees.


Unks37 11-30-2012 06:08 PM

Many thanks for all the help!! I hope to attach some photos to help answer questions. The front end is from a 1976 Mustang II not an aftermarket. It has the strut rod and I don't know if it was moved during the alignment. They wouldn't let me under the car but I could see in rack from the waiting area along with the computer screen of the adjustments and readings. The first photos is of the front end showing the strut rod. I will have to take some more to show the rubbing of the rear of the upper A Arm on the frame. The second is a photo of the alignment screen showing the computer readings. I took it with my phone. I have a paper copy if any questions. I couldn't help by add the third photo of the car.

I haven't really driving it much since the alignment as I am getting some knocking noises that I am trying to track down. I did find that the track bar on the rear makes a noise when you rock the rear of the car. I am also looking at the rubbing of the A Arm on the frame. This has to be making some noises especially when a wheel drops downward from normal ride height.

There are some other issues to deal with, but I wanted to get the "foundation" (alignment, suspension, brakes, etc) right before working on the rest of it.

I really appreciate all the comments and help!

MARTINSR 11-30-2012 06:46 PM

There you go, you need to move the strut/locator bar forward to increase the caster. Now, how you will go about that is another story. I have found many times in the past that the hole the bushings are in at the front is bent back pushing the rod back a little, we are usually talking a half of a degree so that isn't going to be the case here. But how about what those bars are mounted to, is it bolted in or is it welded in? what about the crossmember it's self, is it bolted on? Maybe it could be tilted back?

This brings back memories of a Model A sedan I was collecting parts for but never built, I had a Mustang II front crossmember I had cut out myself to install in it. :D But I never built it, damn I wish I had that body now, it was real nice.

Anyway, making that bar pull the wheel forward can get you quite a bit but depending how much and where it's at now you can also bind the bushings up trying to get too much. I just called my supplier and it doesn't seem that there is any offset upper control arm shafts or adjustable strut/locator bars.

If you post some photos of where the upper control arm shaft mounts and the strut/locator bar maybe we can put our heads together and come up with something.

You do have a little positive camber, I forget how that upper control arm shaft mounts on the back side or outside of the rail but could that rear inner be brought in to get the caster?


MARTINSR 11-30-2012 06:51 PM

I was looking around for you on the net and there is a CRAP LOAD of adjustable hot rod stuff for those cars. There is bound to be an upper control arm or strut/locator with adjustment, I'll try and find one tonight.


Unks37 11-30-2012 08:11 PM


Many many thanks for all your comments and effort. I am now wondering just how good the guy was who aligned the car. It was done at a performance shop that does a lot of work for several car builders in the area. I had to tell him to make adjustments to the 4 bar to get the rear right with the front. At the time I thought it was because more time (money) was involved. I will take some photos tomorrow of the top of the A Arms and the strut bar bracket that is welded to the frame. I think from memory that the bar has room for adjustment with threads still showing on the back of the rod. I will take a good look tomorrow.

I looked and there are several people offering adjustable A Arms both upper and lower. My first thought was to identify the problem and then modify if required.

Again, many thanks!

MARTINSR 11-30-2012 08:48 PM

I am not kidding Unk, when it comes to alignments I have had the damnedest conversations with "experts" on this subject. Let me make this straight, I am no Yoda either, but I have been blown away at guys who don't even know what a particular angle is, or how you can move stuff that has "no adjustment" like a rear end or sub frame to align a car just because it doesn't say so in the computer they can't pull it off. They do normal old alignments when putting new tires on and all, that is fine. But when it comes to something out of the ordinary, something like your car or a damaged car like I work with everyday, they often are quite a bit short in the semi advanced stuff.


Unks37 11-30-2012 11:19 PM


I got some more photos showing the strut rod and the upper A Arm situation. The strut rod brackets are welded to the frame. I think the PO had been throwing parts at it as it has a new Front Sway Bar and he said he had put in new springs with one coil cut to get ride height.

Thanks for all your help,

First set are Right Side

Here is Left Side, it looks the same.

MARTINSR 12-01-2012 11:26 AM

Well, this sucks, not only is there no adjustment (your alignment guy did everything he could and was correct) but it looks like your upper control arm is actually even hitting the frame on the rear! That is where we wanted to go in to increase the caster and decrease the camber, bummer. Ok, the only thing you can do at this point without major surgery is to bring the lower control arm forward with the strut/locator bar. That bracket is welded in too, so getting an adjustable one, or making that one adjustable is all you can do.

Now, let's get back to the specs you have to put things in perspective, it's not good having negative caster, you need caster for high speed stability. To give you an example a S-10 pickup has something like 2 + degrees caster while a BMW 7 series has 4.5 + degrees and a bonneville 200 mph car will have as much as 18 + degrees. Having negative caster is going to do some funky things with handling making the tires bit pretty hard with a little turn of the wheel. I would think you need to do something about this and correct it.

Like I said before I am also concerned that the crossmember was welded in wrong and now if you move the lower control arm forward to get that caster needed you are going to be binding up that lower bushing. So take a good look at it and see if by chance the lower control arm is actually back to far at the spindle and maybe moving it forward will make it "happy", you can only hope. Because if it's where it should be in relation to the crossmember, pushing it far enough forward to make up for a misplaced upper control arm shaft may bind that bushing and cause you problems.

And by the way, that strut/locator bar mount looks a little funky, is that rust I see right at the weld to the frame? That could mean it isn't welded well and water got into the joint.


timothale 12-01-2012 12:25 PM

suspension installation.
Welder series Makes weld it yourself Hot rod components. Their catalog and web site, U tube video's show how to install their pieces, It is a good reference to use when installing a stock M II crosmember like yours. You might be able to pull the wheels, get a string, plumb bob. level and start checking all the pieces on yours, Your car is down in the weeds. does it have dropped spindles? . Usually when one is that low the upper A arms are above the frame rails. There are kits to Bolt in custom M II crosmembers. That would have been the easiest way for the original builder. The upper A arm spring pocket Might have been welde in too low. Those old chevy Frames are not as sturdy as other cars. I would have used a long plate with the strut rod bracket welded to it, then weld the plate to the frame. I have seen some frame bottom piece start to buckle when welded like yours on the frame. a 6 to 8 in plate would give more weld area, spread the load along more of the frame.

timothale 12-01-2012 12:42 PM

possible fixes
the MII crosmember should be level front to back. and the upper A arm mounts sloped to the rear, usually 5 to 7 degrees. depending on front end weight, and how much the front springs compress and drop the front end during braking, Stock M II angles work good on most street rods. You might be able to make some spacers, lengthen the mounting slots to get the upper a arms high enough to clear your frame and have enough adjustability. with the springs removed you could move the suspension up and down to make sure you wouldn't be binding up your ball joints , strut rod, tie rods etc. Shelby moved the locations of the A Arm mounting points to get better handling on the 65 mustangs. but most street rods won't be road racing.

NEW INTERIORS 12-01-2012 12:57 PM

The strut rod on a mustang front end is to stop the bottom arm from moving front to back... It turns the bottom arm into a true a-arm.. You don't want to be pulling the arm back or forward.. It's to center the arm where it is... And to support the forward and backwards motion..They are not ajustable..:nono:

NEW INTERIORS 12-01-2012 01:29 PM

Both arms should be inline with each other.... Run a straite line side to side with the crossmember.. Them arms need to fall on this line.. You can't be having one arm back or forward from this line..:nono: That's why the strut rods don't have any ajustments on them.. From ball joint to ball joint should be in line with each other..

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