Front end shop says I need to replace the FFR supplied spindles

[CJBergquist]

I took my Gen I Coupe (complete kit + IRS) to Custom Alignment in Mountain View CA. Highly respected in the Mustang & Cobra racing community. They inspected the car and told me I needed to replace the early SN95 spindles (FFR supplied) with later (97 - 2004) SN95s that don't have the dog leg. (He isn't trying to sell me spindles or labor to install...he sent me on my way to fix myself and return later.) This is correct the bump steer. I asked about a "bump steer kit" and he wasn't sure the kit would fit with 15" wheels and said the later SN95s was the best way to fix this problem.

What's FFRs thoughts on this? Will the FFR bump steer kit clear the 15" FFR wheels?

This a photo of my spindles.

[CJBergquist]

Not pin drive. Interesting comment on the control arm. I'll wait for FFR expert to comment.

[CJBergquist]

Henry, I think I figured out the issue with the position of the upper control arm. The "new" build manual has two options...donor supplied and FFR supplied spindles. Mine were supplied by FFR...three years ago...and they do not look like the new FFR spindles. So I think I have them in the correct position.

Let's see what FFR say.

FFR, also, can you tell me if I have 87-93 or 94-04 spindles (per old hard copy build manual)?

[frankeeski]

Chris, a lot of things can contribute to bump steer. Bump steer isn't just the relationship of the up and down motion of the suspension translating into toe-in and tow-out. It is also that force that seems to just about rip the steering wheel out of your hand when you hit an uneven area of the road while going straight or in a turn. Managing these reactions can be addressed in a number of ways. First we need to know all of the specifics of your front suspension. Whether you are using manual or power steering and the position of the steering rack. Did you use offset bushings to mount the rack? If power steering, are you using the rack extenders supplied by FFR? A bump steer kit may help and should fit behind the 15" wheels but the 95 spindles you have should also be a good fit. The SAI mod will also be an option you can explore. While I applaud the interest your front end guy has, the bump steer can not be determined by just looking at the parts. Have him set you up with a good basic alignment with the parts you already have and see where it is as far as bump steer.

[Jeff Kleiner]

Your control arms are mounted in the correct location for the configuration you have, that being Mustang spindles (of any vintage) without the SAI adapter. If you were using the FFR proprietary spindles or SN95s with the SAI mod you would use the vertical mounts. The spindles you have appear to be the '94/'95 model year versions which are supposed to offer BETTER geometry in regards to bump steer than the '96 and later ones.

...the bump steer can not be determined by just looking at the parts.

YES! Precisely! Thank you, thank you, thank you Frank! One of my pet peeves is the builders who want to throw a bump steer correction at the car but have never measured to see if they even HAVE bump steer. Set it up, including a baseline alignment, then measure to determine if a correction is necessary. Doing otherwise is akin to asking your doctor to perform a kidney transplant just in case yours is bad!

Jeff

[CJBergquist]

Thanks for the comments and suggestions.

Manual steering, no offset bushings...everything is straight out of the FFR boxes.

The car was put on the rack and all (front and back) initial measurements were taken and recorded. His concern with bump steer was after the measurements were taken.

Anyone from Factory Five going to chime in???

[Jim Schenck]

Chris,

The 94-95 spindles you have are the best donor parts to use as far as bumpsteer for the MKIV chassis. The newer spindles mount the outer tie rods lower than optimum and even with a bumpsteer kit will not allow as good of adjustment as the older ones. Your caster setting also has a big affect on the height of the outer tie rod so make sure it has been set before checking for bump.

[CJBergquist]

Thanks Jim.

Not a MKIV. I have a Gen I Coupe, complete kit with IRS purchased in 2009.

Do I have the spindles and upper control arms mounted correctly?

Upper control arm mount on TOP.

Spindle mounted in the LOWER position on the adapter.

Thanks in advance for your help.

[frankeeski]

Thanks Jim.

Not a MKIV. I have a Gen I Coupe, complete kit with IRS purchased in 2009.

Do I have the spindles and upper control arms mounted correctly?

Upper control arm mount on TOP.

Spindle mounted in the LOWER position on the adapter.

Thanks in advance for your help.

Yes, it appears you have everything mounted properly. Your coupe front end geometry is nearly identical to the MK3 Roadster. Mine is just like your and has very little bump steer. I do however have offset bushing to mount the rack thus lowering it. Like I said, have a basic front end alignment done and see how the car reacts. If you are not please, take baby steps to correct it. Throwing $$$$$ at it may just make it worse.

[Someday I Suppose]

Chris, its interesting to me that the shop felt the newer spindles would fix the bumpsteer, did he give any reason for that? They would also move your wheels out a bit, which for most people is not something they want.

As Jim said, it is pretty well accepted that the 94/95 spindles are the best option for our cars.

I tend to agree with Frank and would do a little driving to see how the car feels. I am also wondering if the shop gave you a measurement for the bump steer, how much is it changing and over what range of motion?

-Scott

[Jim Schenck]

Chris,

Agreed with others that everything looks to be mounted correctly. The donor spindle geometry is slightly different from the first Gen coupe to the MKIV in terms of steering rack location but not in a way that would alter the bumpsteer, everything else is the same. The other thing to be sure of when a shop is checking the car is that they are in the correct range of ride height/travel, if they removed the whole coil-over to do the test and not just the springs it could be that they were assuming a higher ride height that the car will actually have. Also if you want to dial the car in more than the stock tie rods allow, the bumpsteer kit will fit inside a 15 inch wheel.

[CJBergquist]

Thanks everyone for all your input and suggestions. I think I'm going to take baby steps here and just get the alignment done as is and see what I get and go from there.

[CJBergquist]

One last question Jim. What is the official recommendation on ride heights?

[SStrong]

I have a new Mk IV kit. I installed my 94 GT SN95 spindles like you did, in the horizontal plate, following the book. I soon found that the upper control arms had to be shortened to the max, then the camber and toe in could not be adjusted where it needed to be. Had to reinstall in the vertical plates, which puts my adjustments in the middle of their range.
Been my history on this project - take things apart and put back together. I put the brake booster in before the steering rod (as in the manual) then had to redo to put in the bearing at the aluminum cover. Part of the fun!
Ride height is recommended at 4 1/2" according to the build school (3 2x4's stacked is what we used).

[SStrong]

Also, the ride height will change as the suspension settles in.

[Jim Schenck]

Set the ride height to 4-1/2 in the front and 4-3/4 in the rear. When you are setting the height make sure that your spring collars are roughly even side to side (or better yet have the car scaled), to make sure you are not uneven on your corner weights. This will make a considerable difference in how the car handles and even more so in how it stops.

[CJBergquist]

Thanks Jim.

[myjones]

Set the ride height to 4-1/2 in the front and 4-3/4 in the rear. snip .

Jim
How far can I raise the ride height in the front of my 33 (with the coil overs) before the geometry goes bad?
Is there any other spindle etc. that would improve the stance?
I'm running fenders and running boards and that drops the 4-1/2 to 3-1/4 I do plan on a little taller tire
but here in the midwest we have curb gutters everywhere and 5" under the body is about the minimum driveable hgt.
Thanks
Dale
HR431 with a 426 Hemi

[myjones]

Jim
How far can I raise the ride height in the front of my 33 (with the coil overs) before the geometry goes bad?
Is there any other spindle etc. that would improve the stance?
I'm running fenders and running boards and that drops the 4-1/2 to 3-1/4 I do plan on a little taller tire
but here in the midwest we have curb gutters everywhere and 5" under the body is about the minimum driveable hgt.
Thanks
Dale
HR431 with a 426 Hemi

Bump TTT again