Confused about k-member and a-arm swaps...

Topic: Confused about k-member and a-arm swaps... (Read 2819 times) previous topic - next topic

Confused about k-member and a-arm swaps...

January 11, 2007, 04:02:17 PM

Hey Everyone!

I am beginning work on my new project ('88 Sport) and need some help from all of you knowledgeable sorts.

My '88 has a swapped-in '91 Mustang k-member and a full SN95 5-lug swap (a-arms and spindles). I test fit some 17x8 5-spoke Mustang wheels and found the fronts stick out too far for my tastes. The tire (245/45/17) is right at or just outside of the fender lip, maybe 1/4" at most. From what I have read here and on Coolcats, stock '88 a-arms are the same length as SN95's. However, the Mustang k-member is about 1 1/2" wider than the stock '88 Tbird k-member. So this would push the wheels out about 3/4" on each side.

After all of my searching, I think I am more confused than before. Hence, these questions:

1) It seems I could just swap in some Mustang Fox body a-arms to "pull" the wheels back in a little. First, would this work? Second, will the SN95 spindles mount correctly to the Fox Mustang a-arm ball joints?

2) Will a Fox Mustang a-arm cause issues with front-end alignment, strut mounting, tie-rod ends, sway-bar mounting, etc?

3) I also need to replace the steering rack. I'll just get a stock Fox Mustang 15:1 unit and a new PS pump. Any concerns about using a Fox Mustang rack with a Fox Mustang k-member and Fox Mustang a-arms in a Tbird? (LOL!! That really sounds odd....)

Thanks, everyone, for helping me figure this out. It's the first step in getting this old girl back on the road. Albeit a big one! Thanks!

Confused about k-member and a-arm swaps...

Reply #1 – January 11, 2007, 06:00:59 PM

Quote from: bcbickers;123198

1) It seems I could just swap in some Mustang Fox body a-arms to "pull" the wheels back in a little. First, would this work? Second, will the SN95 spindles mount correctly to the Fox Mustang a-arm ball joints?

Yes.
Yes, but you need a 0.330" tall spacer, 5/8" inside diameter , 1.5" outside diameter (or a stack of washers totaling 0.330").

Quote

2) Will a Fox Mustang a-arm cause issues with front-end alignment, strut mounting, tie-rod ends, sway-bar mounting, etc?

Maybe. You might need C/C plates to correct the camber difference caused by the shorter LCAs. I also believe you need SN95 tie-rods to reach the SN95 spindles.

Quote

3) I also need to replace the steering rack. I'll just get a stock Fox Mustang 15:1 unit and a new PS pump. Any concerns about using a Fox Mustang rack with a Fox Mustang k-member and Fox Mustang a-arms in a Tbird?

No concerns. The rack and tie-rods are common between the two models.

Quote

Last edited by bcbickers : Today at 03:07 PM. Reason: Spelling, grammer

Tee-hee.

Confused about k-member and a-arm swaps...

Reply #2 – January 15, 2007, 08:28:43 AM

As I was told here, it's not so much that the K-member itself it wider, rather it's the mounting points of the LCA's. Talk to Chuck W for a better idea as to what will work for your car. Very knowledgable man.

John

Confused about k-member and a-arm swaps...

Reply #3 – January 15, 2007, 11:55:29 AM

Quote from: JeremyB;123221

Yes.
Yes, but you need a 0.330" tall spacer, 5/8" inside diameter , 1.5" outside diameter (or a stack of washers totaling 0.330").

Maybe. You might need C/C plates to correct the camber difference caused by the shorter LCAs. I also believe you need SN95 tie-rods to reach the SN95 spindles.

No concerns. The rack and tie-rods are common between the two models.

I honestly don't know 100% what parts are there. Just what the previous owner told me. I will probably pull it all apart, then evaluate. :)

Quote from: JeremyB;123221

Tee-hee. ;)

Good LORD!! How's that for irony???!! hehee

Confused about k-member and a-arm swaps...

Reply #4 – January 15, 2007, 11:58:54 AM

Quote from: 1BadBird;123961

As I was told here, it's not so much that the K-member itself it wider, rather it's the mounting points of the LCA's. Talk to Chuck W for a better idea as to what will work for your car. Very knowledgable man.

John

Thanks for the tip, John. I will probably ping him. This whole thing is sooo confusing. I really would like to keep the Mustang k-member, since it is already there and lets me use cheaper mounts. All I really want is the wheel and tire to suck in about an inch. I am sure I could correct with backspacing, but then I may have interference problems. Plus, the wheels would be more expensive. (I know...I want to have my cake and eat it too!). :hick:

If I can get some info from Chuck W, I'll post up his recommendations. Thanks again!

Confused about k-member and a-arm swaps...

Reply #5 – January 15, 2007, 12:14:06 PM

No need to "ping" me. This has been covered ALOT on here.
Use the Fox Mustang arms. You may need CC plates to tweak the camber adjustment. It all depends on the car and the ride height.

Confused about k-member and a-arm swaps...

Reply #6 – January 17, 2007, 12:18:37 PM

going from my stock k-member/arms to the mustang k-member/arms wasnt that noticeable. it still sticks the front wheel out a bit.

its better, IMHO, to use the sn95 balljoints and tie-rod ends. there isnt a lot of thread engagement with the fox tie-rod ends.

Confused about k-member and a-arm swaps...

Reply #7 – January 17, 2007, 02:32:02 PM

Quote from: Chuck W;123983

No need to "ping" me. This has been covered ALOT on here.
Use the Fox Mustang arms. You may need CC plates to tweak the camber adjustment. It all depends on the car and the ride height.

Sorry, Chuck. I searched and read every thread I could on k-members, a-arms, wheels, shocks, struts, caster/camber plates, and 5-lug swap on this board, the old board, Coolcats, and Google. Nothing came up where someone had a Fox Mustang k-member and SN95 (or stock 87-88 Tbird arms) that switched to a Fox Mustang a-arm to get back some spacing. I did find a couple of posts where folks had swapped in the updated FMS a-arms and had tie-rod and alignment problems. But they were running the stock k-member (or they didn't say). Just trying to get the best info possible before I tear into the car and find I can't do what I thought.

I still need to finish the interior before I can start on the suspension. Hopefully, I'll have that tackled by summertime and will post up results and pics. Thanks everyone for the help, info, and advice! :bowdown:

Confused about k-member and a-arm swaps...

Reply #8 – January 30, 2007, 01:06:59 AM

Holy hell..unreal how often this comes up.. If u use a stock 87-8 K-member with Fox Mustang (93-older) arms AND C/C plates u can make most wheel/tire combos tuck in but there's usually additional work (see below). If you're doing the 5 lug swap and usin SN95 (94-04 Mustang) spindles, Id suggest stayin with 94-5 spindles as the track width is slightly narrower then 96-up spindles. This will help keep the wheel/tire inboard. I have 18x9 Steeda Ultralites with 275/40/18's on the front of my 87 TC and they are tucked under the car nicely with no rubbing and the car has been mildly lowered.

Now, the fun part. Because the spindle has been relocated significantly inboard compared to stock, the Caster/Camber plates (I used Maximum Motorsports ones) will probably not give you enough adjustment to kill all of the positive camber you just earned yourself by usin the shorter Fox arms. In that case, break out your safety goggles and a die grinder with a good carbide cutter and elongate the C/C mount slots and the large center hole inboard (towards the engine). Have a friend keep the shop vacuum nozzle right where you're grindin so u dont have metal dust and slivers all over. Fun shiznit I know, but its not over yet.

Once you're done with strut towers, get all the stuff put together, install the wheel/tire and then lower the car down on ramps so that the suspension is loaded with the cars weight. Get under it to check strut to tire/wheel clearance and observe tie rod angle and give everything the once-over for tightness. If everything looks good, get the car aligned at a quality shop. If you've done everything above you should now have a degree or so of negative camber and be able to run the common SN95 wheels without havin them stick out of the front fenders east LA style.

* (un?)Helpful Notes *

If you're thinkin you can just elongate the strut tower holes and skip the C/C plates when swappin to Fox Mustang arms, keep dreamin. You'll need ALL of that travel to get the camber back into the negative (top of the tire tilted slightly inboard when lookin down at it from above or from front of car)

If you're thinkin about doin the 5 lug swap usin Lincoln Mark 7 rotors, be aware that the center dust cap will stick out of many of the popular SN95 wheels meaning they either wont fit or will look dumb because your dust cap will be stickin out where the wheel's centercap should be. Also, the old Lincoln brake stuff is ancient and cannot be upgraded like the SN95 brakes can be.

This is serious suspension/brake/steering work, know your limits. I'm the last one to discourage anyone from workin on their own car but dont kid yourself about the work involved or the tools needed here. If all u have is a $20 socket set and a few screw drivers dont expect to get much past gettin the wheel off. Also, this kind of suspension/brake work can get u and others killed in short order if u forget things or have no idea what you're doin. Furthermore, in case you havent already guessed, this is obviously not a 20 minute job. Plan accordingly.

I hope someone makes a sticky on this someday. :shoothead

Confused about k-member and a-arm swaps...

Reply #9 – January 30, 2007, 08:44:53 AM

Quote from: Sumthin Nuu;126553

I hope someone makes a sticky on this someday. :shoothead

I've always wondered why the whole K member/A-arm topic never made it to a sticky.

Confused about k-member and a-arm swaps...

Reply #10 – January 30, 2007, 09:26:46 AM

i used stock 88 mustang arms sn balljoints, and a qa1 mustang k-member. on my car with 99 cobra spindles and 18X9 wheels and i didnt have any fender to tire problems or rubbing. if you want use the 91+93 mustang tie rods they have the increased travel just like the sn ones without the modifications, i went and had it aligned and drove it all summer with no bumpsteer or uneven tire wear.