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I still have to get it to an alignment shop, but it should be close to -0.5.
 

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Discussion Starter #22
Thanks @Knapper and @vegasloki ! Do you guys mind if I post your roll center and camber gain results on this thread? Won't be until tonight or tomorrow morning but I put all the numbers in this morning, the only number I needed was your camber setting, which you guys just provided, so we are good to go.

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Do you get more access to information if you join corner carvers as opposed to not?

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I forget, on some sites links and pictures don't show up without logging in, or downloading information. They have a search feature just like this site, or you could use Google. Here's a related thread here:
 

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Thanks @Knapper and @vegasloki ! Do you guys mind if I post your roll center and camber gain results on this thread?
Fine by me. This is way beyond my level of understanding at this time. I did my own alignment with the Longacre bubble tool. I do want to bring it to a shop to see how close I came.
 

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Discussion Starter #25
I forget, on some sites links and pictures don't show up without logging in, or downloading information. They have a search feature just like this site, or you could use Google. Here's a related thread here:
Thanks @stephen_wilson !!! I was able to download the pdf's from those drop box links. I'll do some reading later and compare them to my measurements. I also see there is a thread linked that discusses the 65 to 67 differences, so I should get most of what I need.

That will be good to compare my suspension dimensions but I still needed some good ride height and tire size information, which I now have. This is all pretty sweet!

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While maybe not relevant I thought I'd share my experience on my 66. I don't do automotive work for a living nor race. I'm a electrician by trade, been to trade school as well as some electronics schooling which means I have some understanding on how angles work and there's more then meets the eye. So when I really became serious about making my Mustang handle well on the street it had to ride pretty much like street car and not a unloaded dump truck. I bought a good suspension book more geared for stock car racing along with asking a lot of questions here. I understand what you're doing but everything is going to be a compromise in the end. At least on the 65/66 the upper control arms are going to be mounted higher then the upper balljoint. Right away you know this is bad on several counts. Roll center below the road surface and positive camber gain. With the stock upper arm, it needs to be lowered by 1.75" to get negative camber gain. You can't lower the stock arm that much because the angle of how the ball joint is mounted will break the balljoint. The most you can do is 1" and that's right at the limit. A aluminum wedge kit was sold to correct the balljoint angle but it was expensive for that it was, like $250. It blocked off the grease fitting and bent the bolts holding it all together. You still had a flexing arm. The next problem with the arm is that they are designed to be used on either side which means zero caster built into them. These cars were designed for maybe 2° + caster. It can get tough getting more caster. To be it seemed the best solution was a purpose built, aka, aftermarket control arm. This could fix all issues at once.

As you lower the control arm, you increase the distance between the 2 mounting points for the spring which lowers the front. On the 65-66 the 1" drop will lower the front by about 5/8". Going to 1.75", I never bothered to figure it out but fair to say more then 5/8". Let's say 1" for argument sake.

Since the Mustang suspension is rear steer it means on extension of the suspension the tires will toe in and toe out on compression. They also have a lot of travel! That means a big change between toe in and toe out. Once you lower the car by what ever means you now have a much greater range of toe in and less range of toe out compared to a completely stock suspension. This comes back to bite many people. You will read guys saying after going over something like a rail road tracks the front end is going to stay up in the air with the front tires squealing until they hit the brakes to settle the car back down. The excessive toe in binds the suspension.

So you start to make compromises on all these things to make them all work as best as possible together.

So what did I do? I started to look for a control arm with a altered ball joint angle, added caster and could be rebuilt with readily available off the shelf items, no proprietary items. It also had to be shorter to help negative camber gain. While I was free to lower the arm more then 1" I stayed at 1" to minimize other unforseen effects. For me the best fit for my needs were Street or Track. Their control arms use rod ends that can be adjusted for increased caster. As shipped, they're set for 3° +. At the time I don't believe there was another brand that offered the feature for caster. I ultimately went for their strut rods with rod ends that are adjustable again for caster. Followed up with their lower arms that use a mono bearing instead of a bushing.

I run 4° + caster, 1.125° negative camber and 1/16" toe in. Tires are 215/60/15. With steel bearings the ride is actually quite compliant. They remove a lot of binding of the rubber bushings. So much so springs that were firm on a stock suspension become too soft. I actually had to move up to Scott Drake. .620", 600#. With stock GT spec coils I would be on my bump stops sitting still with just a second person in the car. The ride is firm but not at all harsh or uncomfortable. I would say similar to a modern Mustang.
 

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@7T02S feel free to post the calcs with those specs. Unless a suspension is engineered for the app like SoT or OT you’re going to be pretty constrained on what you could do with stock geometry and parts. I didn’t mention in the previous posts I’m using roller perches.
 

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These cars respond really well with a few simple tweaks. Just lowering the upper arm 1" makes a dramatic difference. I don't believe it puts it into a true negative curve but helps a lot. It also gets the roll center above the road surface. Add a 1" front bar, good quality shock and some caster with a little bit of negative camber. I'd suggest adjustable struts as one of the first non stock suspension component. Getting rid of the rubber bushings does wonders for stability and better feeling. The car will stop much straighter. I'm a fan of the roller spring perches.

As @vegasloki said Opentracker Racing or Street or Track are two excellent, well respected vendors.
 

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Discussion Starter #29
These cars respond really well with a few simple tweaks. Just lowering the upper arm 1" makes a dramatic difference. I don't believe it puts it into a true negative curve but helps a lot. It also gets the roll center above the road surface. Add a 1" front bar, good quality shock and some caster with a little bit of negative camber. I'd suggest adjustable struts as one of the first non stock suspension component. Getting rid of the rubber bushings does wonders for stability and better feeling. The car will stop much straighter. I'm a fan of the roller spring perches.

As @vegasloki said Opentracker Racing or Street or Track are two excellent, well respected vendors.
Thanks Huskinhano, good advice. One thing though, from everything I've read and from what I've seen in the calculator, is that the mustang's roll center never goes below the ground (at least for the 67 geometry), whether it's with or without the Arning drop, original or extreme lowered ride height, tire diameter, etc. I can get it very nearly on the ground if using the following: without arning drop, small diameter tires, and an extreme drop but I don't think that's a likely combination and it would probably need high static negative camber. I looks like the stock geometry might give around a 2.25" roll center height and then typical mods raise it to around 4.5" to 6.0". Don't quote me on that though, just some observations from the calculator.

Regardless, it's more about how the car feels to the driver than anything else. You're right though, most of the common modifications on this suspension raise the roll center and thus will make the car roll less by getting it closer to the CG, but most importantly, help the camber gain curves which help the inside and outside tires maintain grip while cornering. I think a lower roll center might work well if the camber gain curves could work out and springs, shocks, and sway bars were adjusted accordingly (stiffer as the roll center goes further from the CG); but the only way to do that would be to do some major modifications to most of the pivot locations. I talked with Mike Maier sometime back and he said that a roll center very close to the ground seems to work very well on the track as it helps the forces on the tire's contact patch. I've read that elsewhere too. It's just really hard to do that without non-typical modifications like changing all the pivot locations at the chassis and spindle (x and y) and arm lengths. It would also probably need three degrees static negative camber to work to keep from going positive, since the camber gain curves aren't as good from what I can see. I'm not an expert on this by any means, learning as I read more and play with more settings in the calculator. It all doesn't mean much unless I were to actually try it for myself on the track...
 

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Thanks Huskinhano, good advice. One thing though, from everything I've read and from what I've seen in the calculator, is that the mustang's roll center never goes below the ground (at least for the 67 geometry), whether it's with or without the Arning drop, original or extreme lowered ride height, tire diameter, etc. I can get it very nearly on the ground if using the following: without arning drop, small diameter tires, and an extreme drop but I don't think that's a likely combination and it would probably need high static negative camber. I looks like the stock geometry might give around a 2.25" roll center height and then typical mods raise it to around 4.5" to 6.0". Don't quote me on that though, just some observations from the calculator.

Regardless, it's more about how the car feels to the driver than anything else. You're right though, most of the common modifications on this suspension raise the roll center and thus will make the car roll less by getting it closer to the CG, but most importantly, help the camber gain curves which help the inside and outside tires maintain grip while cornering. I think a lower roll center might work well if the camber gain curves could work out and springs, shocks, and sway bars were adjusted accordingly (stiffer as the roll center goes further from the CG); but the only way to do that would be to do some major modifications to most of the pivot locations. I talked with Mike Maier sometime back and he said that a roll center very close to the ground seems to work very well on the track as it helps the forces on the tire's contact patch. I've read that elsewhere too. It's just really hard to do that without non-typical modifications like changing all the pivot locations at the chassis and spindle (x and y) and arm lengths. It would also probably need three degrees static negative camber to work to keep from going positive, since the camber gain curves aren't as good from what I can see. I'm not an expert on this by any means, learning as I read more and play with more settings in the calculator. It all doesn't mean much unless I were to actually try it for myself on the track...
It's like fixing bumpsteer on these cars. There is the right way and making lemonade out of lemons. I have 72 spindles which have different geometry, the same as Granada. I started to make my own bumpsteer gauge. I began to question how effective this would be since you're only measuring a small percentage of the travel on these cars. So I did it the redneck way, I drove the car and kept adding spacers to the bumpsteer kit. Hey it worked, don't judge me, lol. I played with toe, even going a little toe out. Going toe out makes is going to reduce net toe in but then it makes the tie rod assembly shorter which is the wrong way to go especially since the tie rod arms on the later spindles are angled in more.

I was having a little twitchy feel off center just as I started to make a turn. I was getting a sudden oversteer. I would start a turn, let it settle the it was fine. I felt like it was more of a issue with the rear suspension. I still had original leaf springs. Since I'm cheap and look for bargains I got a great deal on some SD 4.5 leaf mid eye springs that were hardly used, literally brand new from @ophthos I thought they were going to be way too stiff at 195# but hey, they seem to work ok. It fixed my twitchy feel. I had set my toe to 1/16" before the new springs. It must have been the magic number. Anyway at least with street tires, the car drives great. I don't claim to be a expert at all on this stuff just that I can get persistent on something until I get it where I want it. I had many guys here on the forum help me too
 

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I was having a little twitchy feel off center just as I started to make a turn. I was getting a sudden oversteer. I would start a turn, let it settle the it was fine. I felt like it was more of a issue with the rear suspension. I still had original leaf springs. Since I'm cheap and look for bargains I got a great deal on some SD 4.5 leaf mid eye springs that were hardly used, literally brand new from @ophthos I thought they were going to be way too stiff at 195# but hey, they seem to work ok. It fixed my twitchy feel. I had set my toe to 1/16" before the new springs. It must have been the magic number. Anyway at least with street tires, the car drives great. I don't claim to be a expert at all on this stuff just that I can get persistent on something until I get it where I want it. I had many guys here on the forum help me too
My car had the exact same feeling, I think it's the rear axle "taking a set" with lateral load. A distinct lurch in my case. Stock bushings/springs allow the axle to shift to the side quite a bit, there is probably also a bit of roll steer.
 

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My car had the exact same feeling, I think it's the rear axle "taking a set" with lateral load. A distinct lurch in my case. Stock bushings/springs allow the axle to shift to the side quite a bit, there is probably also a bit of roll steer.
That's exactly what it was doing and what I thought as well. Thanks for the verification. Now I know I was on the right track.

After I got the new springs in the back I took it out for a quick trip around the block. The transformation was unreal! I was back from my quick trip around the block 40 minutes later. I was having a great time.
 

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Discussion Starter #33
I spent some time digesting the information from the links @stephen_wilson posted with drawings of the 65 suspension. Thanks again Stephen!

The thing that threw me was the 65 spindle drawing had a ball joint axis angle of 6.3 degrees. That just didn't jive with my early 67 spindles. I went to my shop and measured the angle and it comes out to around 7.7 degrees on both spindles, which is the average of what is show in the pictures with the bar pushed down and then up to cancel it the two diameters.

I had read that this wasn't one of the differences between 65-66 and later spindles. What it does is it pushes the upper ball joint outward or the lower inward by 1/4 inch. Assuming the lower stays at the same spot, that gives 1/4" more wheel clearance at the top.

Either they are different, or the drawing of the 65 spindle is wrong. Regardless, I'll stay with the dimensions I measured in my spindles.


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