1966 Front End Alignment Specs- 6 Cyl Convert - Ford Mustang Forum
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post #1 of 9 (permalink) Old 04-23-2011 Thread Starter
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1966 Front End Alignment Specs- 6 Cyl Convert

I took my car to my local Firestone today, for a set of FR380 tires, 195/75R14's. My car is a 66 Convertible, 6 Cylinder.

I also wanted to get the front end aligned, since the car had a pretty major pull to the right and with the old bias ply tires, really handled poorly.

Lucikly(or so I am thinking), they didn't have the necessary shims to do the correct alignment. They were going to align by the Ford factory specs for caster/camber/toe.

I have done enough reading to know that it seems that the Ford specs for alignment with the newer radials and 45 years of knowledge are not maybe the optimal specs.

Currently, the car is pretty out of spec for camber/caster and toe. See my attachment, it is of the shop print out of the current specs.

Here is something I found here on this site that are some recommended settings for my 66 for an alignement. I am going to assume that these settings would apply to the 6 cylinder model also(but not sure of that totally, because an 8 Cyl would have a heavier front end):

Please align to these specs ď1960-1966 Mustang and Falcon Performance Alignment with or without UCA dropĒ.

These specifications are in order of importance.

1. NO more than .25 degrees difference between driverís side and passengerís side.

2. +2.0 to +3.5 degrees caster.
NOTE: for cars with Adjustable strut rods. Please attain as much caster as possible using the shims (at least 1.5 to 2.0 degrees), and then use the adjustable strut rods to increase the caster and make the sides the same. Also, please note that the caster difference between the driverís side and passengerís side needs to have no more .25 degrees difference prior to the adjustment of the strut rods.

3. -.5 to 0 degrees camber. No positive camber, please. There is no problem having a slight variation from driverís side to passengerís side to account for the crown in the road.

4. 1/16" to 1/8Ē toe in

If you run into any problems attaining these specs, please call me (your phone number here).

For my car, would it be reasonable to use this as a guideline to get the alignment to something driveable, versus the Ford specs which is what they were going to go by, if they had the shims today.

Maybe this delay is for the better, if I end up with a better alignment using the above?
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post #2 of 9 (permalink) Old 04-24-2011
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Hello Jeff,

Hope all is good up north. I just finished my build and am planning on getting the front end aligned next week. I have been researching this as well and you are in the ball park.

I have learned that for a good street tune use the following:
+2.5 caster
-0.5 camber
1/8" toe in

Take care,


1966 Coupe - V8 Conversion
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post #3 of 9 (permalink) Old 04-24-2011
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Are you sure those guys at Firestone know what they are doing? Their numbers do say you badly need an alignment but look at the rear axle numbers. Your rear can't be aligned but their numbers say your (car's) rear is in bad shape also. If your rims are straight, the only way I can explain those rear numbers is if the axle housing is mounted wrong and the left axle tube is bent. Do you think that is possible?

If they don't have any shims they probably don't do old Mustangs and you might want to go elsewhere. I have also had an alignment shop tell me my car with shims could not be aligned properly when it really meant they didn't want to go to the trouble of doing the job correctly. That was when I learned how to do my own alignments and properly aligned the car they said couldn't be done.
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post #4 of 9 (permalink) Old 04-24-2011
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I have to agree with IVY66. a lot of these places have no idea how to align an old car much less anything else. When I wanted to have my bias plys mounted I went to one of these tire places, and they told me they didn't have the right tools, yea right!

I would recommend finding an alignment shop that been around at least 20 or so years, they have people probably who aligned the cars when they were new! I am lucky to have found one here in Nashville, he opened shop the same decade the Mustang came out!

I must say though, I've heard all this bad stuff about the bias plys. but I have no problem with mine. After the alignment the car rides wonderfully with them. I can let go of the wheel and she goes straight as an arrow. Now I'm not a speed demon, but doing 70-75 on the Highway, they are great.

1966 Mustang convertible
Born in Dearborn Jan. 17th 1966
Reborn August 2013
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post #5 of 9 (permalink) Old 04-24-2011 Thread Starter
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Thanks to my friends thus far on the replies. Here are my comments in regards to them:

1.John- thanks for the suggestions. The Ford manual spec for 6 cyl cars is Caster 0-2 degrees pos. 1/2 in. variation. Camber -.025 to pos 1 1/4 deg. Toe in 1/8 to 3/8. I am leaning towards the 2 or 2.5 deg Caster. I am only hoping that that spec will work for 6 cyl also. The 8 Cyl Ford spec for Caster is -1 to +1 deg caster. I guess 2.5 isnt all that radial for a 6 cyl alignment. Will go with -0.5 camber. Will go with 1/8 in toe in. Good luck getting yours going, I saw first hand all your putting together, I know you have been busting it to get ready for the spring.

2.Gary- I shared the concern with them about their expertise doing an older car. They have some guys on staff that know how to do older cars, they even assigned a more senior tech to my car because it is a "classic". They used to carry the shims, but stopped in the 90's. I was glad they knew what shims are- they are ordering and will have them in this week. I am going on gut that they are going to be able to do it, just based on talking to them. As far as my rear alignment, I did notice too the left was outta whack. The rims appear perfectly fine, so something is out of adjustment. Honestly, not sure what can be done there to adjust all that.

3.Terry-I am hoping that they can do the work too- I dont know of any other front end places right at the moment- it was more of I am going to take a chance based on gut feeling, since the car was there for the tires anyway. I quizzed them enough on the phone to get a feeling that they might have a clue on older car alignments, unless I wouldnt have let them do it.

In regards to the radial vs. bias ply. I can report that the drive home, in spite of the still poor alignment, the car tracked and did not drift nearly as poorly as before. I am glad I have the radials on and actually was happy to find the Firestone FR380's,as they no longer make them and I wanted an American branded white wall on my classic American car. (unlike one shop that wanted me to put some Japanese whitewall tire on my car, haha)

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post #6 of 9 (permalink) Old 04-24-2011
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I would strongly encourage you to do the "drop" on your suspension before they finish the alignment.

Arning/Shelby Suspension Drop

As for the rear alignment numbers, I had a shop give me a printout one time with something similar. I spent a whole day with the car on a lift measuring the axle housing to find the "bend". I finally decided they were full of beans.
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post #7 of 9 (permalink) Old 04-24-2011
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Its somewhat odd that they would even print the rear wheel data on a solid axle car. It looks to me as if they didn't have the equipment mounted on the car correctly which would help explain the report of the the rear all screwed up.

There are very few owners who understand rear wheel alignment and the shops try to make it out to be terribly exotic and high tech. In reality, many of the shops are only fishing for more, usually a LOT more $$ to do a 'precision 4-wheel', instead of a 2-wheel alignment. The rear wheels are rarely hard to adjust even if they ARE adjustable which they are NOT on almost any car from the 60s, 70s or even most 80s.
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post #8 of 9 (permalink) Old 04-24-2011 Thread Starter
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David- thanks for your input. I have read your comments on the other board Fomoco for a long time, so I know your input is welcome on any topic. For now, I am going to hold off on that good idea to do the drop. Maybe next year on that.

Gary-I am hoping too that the rear is some sort of analomy- but I am going to inquire nonetheless how they got that reading.

My ultimate question regarding if the specs that are being thrown out as good suggestions, in the ballpark of 2.5 degrees positive caster are valid for the lighter front end of a 6 cyl? If we look at the overall variation in the spec from a 8 cyl to a 6 cyl caster wise, setting the caster to +2.5 deg on a 6 cyl with a max tolerance of +2.0 deg caster seems like a very minor change verus setting an 8 cyl caster (which has a max +1 degree max tolerance) to +2.5 deg.

Proportionally, the 8 cyl caster set at +2.5 is a lot more of a deviation from Ford specs(it is +1.5 deg more than the max Ford spec of +1 deg caster) than a 6 Cyl caster set at +2.5 deg (that is only +0.5 deg more than the 6 cyl max Ford spec of +2.0 deg caster)

Am I over thinking that, or does the proportional differnce make a difference between caster on a lighter front end. In the equation above, I should maybe consider setting this caster at +3.5 deg on this 6 cyl car, to mimic the amount of change that is used for an 8 Cyl.

Or maybe the Sunday night funnies have hit and I am overthinking it an should just set the damn thing to +2.5 deg and call it a day.

I would rather do it right once-

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post #9 of 9 (permalink) Old 04-25-2011
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The problem with a lot of positive caster is that when you turn the wheel you are actually lifting the front of the car; the more caster, the more lift. For a manual steering car, or for a heavier car that means the steering effort is more difficult with increased caster. Less caster specified for a V-8 likely only meant that Ford didn't want the manual steering on a V-8 Mustang to feel 'heavy' so that 98-pound grandmothers would still want to drive one. (No offense meant to any of you 98-pound grandmothers. )

With more caster the road feel is more solid and stable since as gravity is pushing the car down to its lowest position its also centering the steering for you. German cars typically use 10 degrees caster but then they all now have power steering. They are also known for much better road handling than a zero degree caster Mustang from the 60s.

I still have to verify the exact numbers, but my two '66 Mustangs, both with manual steering, drive much differently. The coupe is setup with factory zero caster and is rather blah handling. The heavier GT convertible has more caster and is a pleasure to drive compared to the coupe. Hardly seems like I am driving the same car. The quicker GT steering is part of that different feel, but not nearly all of the difference.
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