mustang II spindles

zm830101

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May 16, 2005
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warner robins, ga
i have a '66 coupe and i want to know if it is possible to use a mustang II style spindle on the stock suspension and steering components? i want a drop spindle but i don't want to swap out all of my steering and suspension components. i like the stock stuff just fine. unfortunately, all the drop spindles i see are for the fox bodies and MII suspensions.

something like these on a stock suspension and steering
http://www.wilwood.com/Start/New_Product_Release/ProSpindles/index.html
 
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Helmantel

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Aug 9, 2006
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Mustang II spindles are front steer (steering arms point forward) and can consequently not be used on classic Mustangs (unless you don't care about weird steering geometry)

The Wilwood spindle is a possible candidate, since it uses bolt on steering arm, but unfortenately the steering arm geometery is not a good match: the tie rod would end up about 2" too high. Enormous amounts of bump steer would be the result.

Maybe you could fix that with a bumpsteer kit with a very long stud, but that would probably flex a lot.
 

ace_xp2

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Aug 29, 2009
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From what I've read, they can take the same balljoints as stock classic mustangs.
Haven't verified myself, so fwiw.

I'm looking at the same thing, They've got more KIA, so you'd have to lengthen the lca or shorten the uca. They're hub face is further inward then classic mustang spindles, so I'm thinking lengthen the lower. (I'm also thinking limiting rc movement is more valuable than gaining camber curve, as the curve can be made acceptable with stock parts)

Also, the wilwood spindle is still a little shorter than a classic mustang spindle, so you'd have to drop the upper arm holes more than the typical inch to get the rc and camber gain back in the ball park. If you keep the stock uca spring mount this will also drop the car a considerable amount, as both the shock tower mounting and the balljoint position will be lower. Not necessarily a deal breaker, just something to consider.
This won't be a problem with the typical coil over lower arm mount.

The most pertinent part of all this for you is that you'd also need a longer lower arm to make this work. user 5280 here made one from circle track parts that looks easy to replicate.
 

Helmantel

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Aug 9, 2006
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I don't remember exactly how much the UBJ moved inwards, due to the increased KPI, but it was a small amount and is probably within the adjustability range of the suspension (either removing shims from the upper arm for 65-66 or moving the LCA inner pivot outward).
 

5280/4

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May 21, 2009
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From what I've read, they can take the same balljoints as stock classic mustangs.
Haven't verified myself, so fwiw.

I'm looking at the same thing, They've got more KIA, so you'd have to lengthen the lca or shorten the uca. They're hub face is further inward then classic mustang spindles, so I'm thinking lengthen the lower. (I'm also thinking limiting rc movement is more valuable than gaining camber curve, as the curve can be made acceptable with stock parts)

Also, the wilwood spindle is still a little shorter than a classic mustang spindle, so you'd have to drop the upper arm holes more than the typical inch to get the rc and camber gain back in the ball park. If you keep the stock uca spring mount this will also drop the car a considerable amount, as both the shock tower mounting and the balljoint position will be lower. Not necessarily a deal breaker, just something to consider.
This won't be a problem with the typical coil over lower arm mount.

The most pertinent part of all this for you is that you'd also need a longer lower arm to make this work. user 5280 here made one from circle track parts that looks easy to replicate.

Thanks for the bump! The ball joint tapers are the same. Making your own steeering arms is a must. Unless you want to run front steer. As for making your own control arms, my upper was more modular off the shelf parts. The lower was more custom fabrication. The gussets for the tube to ball joint holder are specifically made to maintain a certain ball joint angle. Mine is a seven degree angle to match the KPI. I also ran specific camber gain and designed control arms lengths to minimize roll center movement.

I see this as a plausible option but a lot of work to make it right would be needed. I can help.

























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ace_xp2

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Aug 29, 2009
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I don't remember exactly how much the UBJ moved inwards, due to the increased KPI, but it was a small amount and is probably within the adjustability range of the suspension (either removing shims from the upper arm for 65-66 or moving the LCA inner pivot outward).

Wow, that could change a lot. I knew I should've finished the wishbone model I was working on. I just assumed I'd need new arms and since that step is far further along on my build then where I'm currently at, I gave it no more thought.

5280, I didn't realize you'd altered the ball joint angle. There's a guy who posted his build up long ago on corner carvers:post 157 on. And it doesn't appear he bothered, I wonder where the range would become an issue? If it's in droop it may be acceptable, unless you're prone to jumping the car.
 

5280/4

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May 21, 2009
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they have a different spacing. Check out the TCP rack. There are four holes drilled in the center link. I think 67 was narrower. I can check when I get home I will look at my 65 mustang with a TCP rack and see which holes I used.
 

rbohm

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Apr 12, 2002
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the mustang ll spindles have been used in a rear steer application, but only on a drag car where poor ackerman steering geometry makes no difference. to try and use the mustang ll spindles in an application other than a front steer for anything except going in a straight line you will have steering geometry problems. you can heat and bend the steering arms to match the rear steer spindles, but you need to be, or have, an expert in doing this kind of modification otherwise you run the risk of ruining the steering arms.
 

ace_xp2

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Aug 29, 2009
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The wilwood (and by extension,stock) ones have very near zero ackerman in them.

However, that's actually why I was asking about the center link.Moving in the tie rod mounts in would let me fab the new steering arm in as well to increase ackerman. It would likely be too much at one inch inwards, but if you in turn shorten the arm lengthwise you'll alter the tie rod arm angle in plan view and decrease ackerman. This will hopefully allow me to work out an acceptable value.
(does anyone know how to calculate ackerman change due to tie rod arm angle?)

Doing this would bring the arm further in towards the pin and further in towards the body, both helping to get more tire under the car.

If you could 5280, Though I can't imagine they'd be much different than 1" as that's what the lower arm mount moved in by.
 

5280/4

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May 21, 2009
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sorry i forgot to check, The mustang was loaded on the trailer. Im going drag racing this weekend if it doesnt rain.

I think it is moved inboard about 1.5" on each side.

I have heard the 67 LCA was 2" longer than a 65 but i can not verify this.

As for using a zero ackerman steering arm. The limited reading I have been doing on ackerman states that the line between the ball joint on the LCA and the tierod on the steering arm should point back to the center of the rear end, when lookig from the top.

http://woodwardsteering.com/images/cat05 pdf 64-79.pdf

This is a great link.

The idea of bringing the inner pivot points of the tierod inboard would really mess with the bumpsteer. I would avoid that, unless you plan on also moving the LCA pivot points inboard and lengthening the LCA. Again a lot of geometry you would need to figure out. I would suggest a suspension analyzer program. Like performance trends, they have a 10day freee download.
 

ace_xp2

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Aug 29, 2009
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If you move both points on the tie rod in the same amount,and maintain tie rod angle, I thought you'd maintain the bumpsteer curve. Not that the stock one is ideal anyways.

From what I've read, going for a ackerman more than 100% can often net benefits, especially in autox, but the question is how much is too much? I'll have to work out what I'll end up with by moving the spindle arm mount point around. At least I won't have to get a whole new spindle if my first attempt doesn't work out.:D

I'm thinking that if I work out the acceptable position based on ackerman, I can make a mock up steering arm to work out bumpsteer with, and then get a arm made based on that.Be nice to not have bumpsteer shims.
 

5280/4

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May 21, 2009
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ideally you want the LCA and tierod to be parralel from front view and share the same pivot points. Since this is not usually possibly unless you have a really short steering arm some changes can be made. But i would still keep the tierods pivot very close to the LCA chassis pivot. woodward steering link has a ton of info. It should answer all your questions.
 
The wilwood (and by extension,stock) ones have very near zero ackerman in them.

I measured the MII spindle as having 7 degrees positive ackerman (+/- 1 degree with the tie rod pivot outboard of the lower BJ pivot). The stock 69-73 spindles have 14 degrees negative ackerman (+/- 1 degree with the tie rod pivot inboard of the LBJ). I haven't measured the Wilwood ProSpindles because I have them mocked up with my rear steer arms and I don't want to take them apart just to take a measurement, but I suspect that it's pretty close to the MII angle as well.

Just looking at the shape of the arm is very misleading. You have to look at the relationship of the pivot points.

However, that's actually why I was asking about the center link.Moving in the tie rod mounts in would let me fab the new steering arm in as well to increase ackerman. It would likely be too much at one inch inwards, but if you in turn shorten the arm lengthwise you'll alter the tie rod arm angle in plan view and decrease ackerman. This will hopefully allow me to work out an acceptable value.
(does anyone know how to calculate ackerman change due to tie rod arm angle?)

To find the ackerman angle, measure the angle between the tie rod pivot and the LBJ pivot. As stated by 5280-4, when viewed from above this should form a V intersecting the center of the rear axle. When you say move it in an inch, you need to make sure that ends up putting it near, but outboard of the V line. The only reason you would ever need 100% ackerman is if you had solid tires. The slip angle on the original 14" and 15" balloon tires was huge. Even with modern short sidewall/low aspect ratio tires there is still some slip angle. It's better to make the intersection well behind the rear axle so the steering arm more closely aligns the tie rod with the LBJ, thus minimizing bump steer.
 

ace_xp2

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Aug 29, 2009
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Thanks for the ackerman figure, I've been wondering about it. I'll need a new arm anyways, but I'm curious how much the normal one would need to be shimmed to get to zero or slightly negative.
It's interesting to note that the mustang 2 had a shorter wheelbase along with less ackerman in the arm compared with the early gens.

The only thing with using the arm line to measure ackerman, is that it doesn't take into account rack (or center link, as the case may be) position, which also has an effect on ackerman. That's why I'm hoping that I can find an acceptable position to move the tie rod mount towards the spindle, as that will lower the likely excessive ackerman caused by moving the mount in towards the chassis x amount.

That may lead to bumpsteer issues, but as the arm is still unplaced in a vertical direction, I can put in a place that's hopefully ballpark. Making it perfect isn't a huge goal, just acceptable would be fine.

This in combination with the lower upper ball joint height, and the higher spindle pin will hopefully be enough to get a 17" rim up and over ball joint (and around the steering arm). That will let me both add rim and lose scrub.
 
It's pretty easy to get a 2" drop spindle to fit inside a 17" rim. In fact I've test fit mine in a 17x9" rim and it fits, although just barely. I designed a dropped steering arm with an adjustable offset (nominal is 5.5") that has as much drop as I could get and still fit inside the rim. This is a prototype piece with a -7 degree Ackerman. The factory -14 degree Ackerman would have made it a lot easier to fit in the wheel, but the bumpsteer geometry wouldn't be as good. If my tires squeal too loudly in a tight parking lot maneuver, I'll make a -14 degree arm and test that as well. As soon as my caliper brackets are ready (hopefully next week) I'll post some pics. The machine shop seems to have put my project on the back burner (and the heat down to LOW).

The key to making it work is the placement of the inner tie rod pivot. My center link moves the pivot point much higher than I've seen on anybody else's design (although this causes it's own problem as the increased moment arm causes the centerlink to want to torque over when you change directions). My Cardomain site has pics of the first gen design that uses stock disc spindles and you can see it's higher than most anyone elses.

I've been working on the ProSpindle conversion since August. I had to design a new centerlink, centerlink to rack adapter, anti sway bar mounts, anti torque guide, custom hats, caliper brackets and steering arms. I also changed the hubs and rotors to different Wilwood part numbers and re-drilled the rack mounts to re-clock it. Modifying the front suspension is a pain as anything you do will have an affect on something else (that you didn't intend and may not have foreseen!)

Ideally the rack would be placed so that there is no angle fore and aft on the tie rods so that there is no affect on Ackerman.
 

ace_xp2

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Aug 29, 2009
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Wow, I love that center link!
Before I realized I'd be putting the tie rod through the body, that's the route I was going to take in combination with the stock steering arms. Never is that easy though :(.

So you used the 2" drop prospindle? I was worried that would put my tires into the fenders, unless I in turn used springs tall enough. Which would then throw the geometry off. Are you going to have to do fender work?
I wonder how close the 69 fender to wheel height is to a 65?

I don't know that you necessarily want to shy away from using rack placement to affect ackerman. I just don't know how to measure its effect yet. Time to start searching...

Oh, Did you manage to keep full steering with that rim? or did it hit the a-arms? Do you think you could go any further back then you were?