Wheels-Tires Need Some Help - Brakes Upgrade/Wheel fitment

KRUISR · Mar 22, 2026

I agree with AeroCoupe, put the rear end in as it is - axles and all. The rear brake setup will be done already. Just plumb it. And it the prop valve you put in is from a non-ABS car you can keep the single brake line running to the rear, use the factory style flex hose at the center of the diff. Then use the factory splitter and lines over to each rear caliper.

limp · Mar 22, 2026

The first 9' I had built for my 77 stepside had a 31 spline 3rd member.. Its just 3 splines but it is substantially larger in diameter when you compare one side by side.... When I said 1st, I ended up using " made to order" 9" rears in all of my projects where I could... MUCH better and LOTS of parts available for them compared to the GM 10 and 12 bolt rear ends... Easier to work on and set up too.....
Mustang got 31 spline cuz " while I was in there" ....

jaygee15 · Mar 22, 2026

AeroCoupe said:
Why do you want to swap to Fox length axles? The rear end as is will bolt up under the car and it has disk brakes. Now if you do not want the five lug I get that but if you are going to five lug then just get 94-98 length axles.

As far as 28 spline vs 31 spline axles go are you planning on running slicks? If not then just rebuild the traclok and put good (Moser or Strange or the like) axles in it and move on. I am running Moser 28 spline axles in both my cars but I do not run slicks.

I’m not saying it’s not a good idea but money could be used else where if you are on a budget.

I want the narrower setup of fox length axles so I can runn a deeper dish rear wheel. No slicks, this will be a street car.

jaygee15 · Apr 1, 2026

If I'm needing to replace tie rods, should I also just swap to sn95 lower control arms and anything else like a bump steer kit?

KRUISR · Apr 1, 2026

Depends. How is your front alignment right now? If it is correct, then you could put SN95 ball joint in your fox control arm. Take a picture of your current set up from the front with suspension under load. You will want to see the control arm and tie rods. This can help determine if you need a bump steer kit.

You want the line through the pivot point on inner tie rod and outer tie rod to be as close to parallel as possible to the line through the control arm pivot point and pivot point of the ball joint. I'm not perfect here but I am pretty close. I have a 90GT with 96-04 spindles, I relocated the lower control arm mount inward 0.5" and upward 0.5", and I used offset rack bushings to LOWER the rack (most use them to raise the rack). I am using stock tie rods on both ends and NO bump steer kit. My lowered set up pictured above.

86HO5.0 · Apr 3, 2026

jaygee15 said:
If I'm needing to replace tie rods, should I also just swap to sn95 lower control arms and anything else like a bump steer kit?

Since you're running a 94-98 rear end, I'd recommend swapping to SN95 arms and inner tie rods. You won't need a bump steer kit if running SN95 arms w/94-95 spindles on a Fox.

Buy CC plates and some S197 wheels as well.

AeroCoupe · Apr 3, 2026

I am going to strongly disagree here. Using SN95 front control arms on a Fox has little to do with bumpsteer but more to do with camber. You can get bumpsteer with Fox or SN95 control arms. Bumpsteer is about steering geometry so you have to correct that to eliminate bumpsteer. The whole key to bumpsteer on a street driven car is getting the inner and outer tie rod assembly parallel to the control arm. There are two ways to do this and one is with a tapered bumpsteer kit and the other is with a bolt through style kit. Generally the tapered kit will work on street driven cars with moderate drop in ride height so call it up to an inch and the bolt through are for drops in excess of 1". I have seen a couple of street cars that needed the bolt though with the 1" and less drop and we just chalked it up to the sloppy build tolerances of these cars.

Biggest issue with running SN95 lower control arms in the front will increase the track width 0.75" per side. This will move the bottom of the front tires out creating a lot of negative camber. This can be compensated for but it will depend on your wheel and tire combination. Compensating for this can be one or more of the following:

1) Slotting the holes in the struts
2) Caster/Camber plates (best if you ask most on this board)

Remember that when utilizing SN95 spindles they will increase the track with as follows:

94/95 Spindle - 0.120" increase in track width per side
96-04 Spindle - 0.320" increase in track width per side

On a street driven car why not just run the Fox length control arms with SN95 ball joints? This is what run on both cars with the full SN95 five lug swap. You can even run Fox length control arms with Fox ball joints with a 0.330" stack of washers under the castle nut. This puts the castle nut in the right position to utilize the cotter pin. Washers have to be checked to have an ID large enough to keep from an interference fit on the ball joint stud when torquing the castle nut.

86HO5.0 · Apr 3, 2026

The 94/95 Spindle adds positive camber, 1.7 degrees IIRC. This combined with narrower K-member on the 86 might cause issues with the ability to achieve enough negative camber, even with CC plates. The SN95 arms remedy this. The SN95 arms also improve stock fox bump steer geometry slightly per MM's website.

96-04 spindles make bump steer corrections impossible when using a Fox K-member per Jack Hidley.

86HO5.0 · Apr 3, 2026

SN95 arms will cause negative camber, not positive. Combined with a higher offset wheel (S197) increases tire clearance and turning radius dramatically.

AeroCoupe · Apr 3, 2026

I got ahead of myself as I was focused on the SN95 control arms so I corrected the camber talk so thank you as that was some serious misinformation on my part. In your case (1986 and down cars) I agree that using an SN95 control arm is great but not with the stock 87-93 k-members as the lower control arm pickup points are moved further out.

I have a full MM suspension on my Coupe and a Griggs Racing suspension on the T-Bird and both have Fox length arms. I have been though a lot of this as it took me a few years to piece together the suspension for the Coupe. I fully now know what not to do...the hard way but it all worked out.

KRUISR · Apr 3, 2026

86HO5.0 said:
The 94/95 Spindle adds positive camber, 1.7 degrees IIRC.

How much camber are you trying to get?

86HO5.0 said:
96-04 spindles make bump steer corrections impossible when using a Fox K-member per Jack Hidley.

That's funny, I have 96-04 spindles with fox control arms that have been relocated 0.5" inward (same control arm mount location as pre-88 cars). My issue was too much camber so I slotted the strut mount slots and have camber plates almost all the way up. Alignment is perfect and haven't touched it in 10 years with no abnormal tire wear.

When I first assembled the car I had a pair of SN95 tubular lower arms but took them off as the tire was pushed out too far.

To get the front aligned anywhere close to spec the top of the tire would not tuck into the fender. The lowers were changed out for stock fox lowers and all is good.

EDIT: Rim shown here is a 16x8 with a near 0 offset IIRC.

86HO5.0 · Apr 3, 2026

Agreed with the SN95 arms and 87-93 Members. Even with 45mm offset wheels the track width will cause fender clearance issues.

jaygee15 · Apr 5, 2026

So sn95 inner and outer tie rods with the sn95 control arms? And no bumper steer kit?. I'm not sure what I'm going to do as for as lowering the car yet, or which K member I will be getting. I will be having some custom 2 piece wheels made as far as wheels go.

AeroCoupe · Apr 5, 2026

Again, unless you move the attachment point inboard on your stock k-member it is going to push your front wheels outboard 0.75” with the SN95 control arms.

SN95 rack with Fox control arms you will want to use Fox inners and outers unless you opt for a bump steer kit. If you get a bump steer kit then it is the outer tie rod.

Mustang5L5 · Apr 5, 2026

Unless you actually measure bump-steer, it’s all just a shot in the dark with regards to what modifications do what to bump steer. Keep in mind your caster adjustment can also make a huge impact. Two folks can have the same suspension setup, but different caster settings and your bumpsteer measurements will be drastically different even eyeballing the parallel of the suspension arcs. So what works on one car won’t necessarily work on another.

This is a pretty heavy technical subject.

Measuring bumpsteer is also a huge PITA. I have the kit from MM and did it once. You have to make your suspension adjustments and dial in your alignment, then measure your ride height and pull the springs. Then measure. It’s quite a bit of work. Make one change and you need to redo it all.

When I get back on my PC I can post a snip or two from my working excel file when I did my car showing how much one spacer on the bumpsteer kit changes things.

KRUISR · Apr 5, 2026

jaygee15 said:
So sn95 inner and outer tie rods with the sn95 control arms? And no bumper steer kit?. I'm not sure what I'm going to do as for as lowering the car yet, or which K member I will be getting. I will be having some custom 2 piece wheels made as far as wheels go.

What is your obsession with SN95 control arms? As stated above, you are likely better off overall with foxbody control arms.

AeroCoupe · Apr 5, 2026

I have access to the MM bumpsteer gauges and after I helped my buddy set his road race car up a couple times I told myself hell no on a street car. I had the alignment shop put as much positive caster in both cars (equal on both sides) and just made the tie rods parallel to the lower control arms. It’s worked for over 20 years.

Mustang5L5 · Apr 6, 2026

AeroCoupe said:
I have access to the MM bumpsteer gauges and after I helped my buddy set his road race car up a couple times I told myself hell no on a street car. I had the alignment shop put as much positive caster in both cars (equal on both sides) and just made the tie rods parallel to the lower control arms. It’s worked for over 20 years.

I guess i didn't really finish my thought. I agree with you and that's what i'd tell 90% of folks setting up a car for the street to do.

Splitting hairs on a street driven car to get every single technical measurement dialed in just isn't going to make sense for the vast majority of folks.

jaygee15 · May 6, 2026

I am gettting ready to install the fox length axles into the 94-98 GT 8.8 rear end.

What parts do I need to connect the sn95 GT brake lines to the fox body brake lines?

AeroCoupe · May 6, 2026

Are you going to drums or staying with the SN95 disc brakes?

Wheels-Tires Need Some Help - Brakes Upgrade/Wheel fitment

KRUISR

limp

wrap a little cheese around it and its a done

jaygee15

Member

jaygee15

Member

KRUISR

86HO5.0

Active Member

AeroCoupe

lube between the nut and the face. I know my lubes

86HO5.0

Active Member

86HO5.0

Active Member

AeroCoupe

lube between the nut and the face. I know my lubes

KRUISR

86HO5.0

Active Member

jaygee15

Member

AeroCoupe

lube between the nut and the face. I know my lubes

Mustang5L5

That is…until I whipped out my Bissell

KRUISR

AeroCoupe

lube between the nut and the face. I know my lubes

Mustang5L5

That is…until I whipped out my Bissell

jaygee15

Member

AeroCoupe

lube between the nut and the face. I know my lubes

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Wheels-Tires Need Some Help - Brakes Upgrade/Wheel fitment

wrap a little cheese around it and its a done

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lube between the nut and the face. I know my lubes

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lube between the nut and the face. I know my lubes

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lube between the nut and the face. I know my lubes

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lube between the nut and the face. I know my lubes

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lube between the nut and the face. I know my lubes

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