differances in "K" members

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differances in "K" members

Reply #15 – November 30, 2005, 08:27:50 PM

have you driven the car since? how is it working out?

differances in "K" members

Reply #16 – December 01, 2005, 12:53:35 PM

I'm still a bit muddy on some of the k-member specifics...

What I know is 83-85 Cougar/T-birds used the same k-member as '79-'86 Mustangs. In '87, the Mustang k-member control arm mounting points moved outwards 1".

Now, on the coolcats website, it shows the same track width for all '83-'88 cars. Since all wheels use the same backspacing, this can't be. If '86-'88 cars use the same k-member, but '87-'88 cars use 3/4" wider control arms, the track must increase. Anyone have any info on this?

differances in "K" members

Reply #17 – December 01, 2005, 01:00:57 PM

It is indeed possible.

If i remember correctly, the control arm mounting points are spaced farther apart on the mustang k-member, so with the shorter arms, the track width is the same

on the Tbird member, the control arm mounts are closer together, so the extra length in the arms will still give the same track width, that also give a more plush ride, and somewhat "softens" the spring rates

differances in "K" members

Reply #18 – December 01, 2005, 01:05:26 PM

Quote from: Tbird232ci

It is indeed possible.

So '86 Cougars/T-birds use Mustang k-members?
Coolcats says our cars got a unique k-member in '85, but my '85 uses Mustang motor mounts. If the unique k-member didn’t appear until '87, then the track width would be the same (and everything would make sense).

differances in "K" members

Reply #19 – December 01, 2005, 01:31:13 PM

Late 1985 cars have been known to sport the updated 1986-88 K-member. All the other 1983-85 cars, though, have the Mustang K-member from those respective model years. There were some very minor changes made to Mustang K-members between 1979-93 but in general, a Mustang K-member works on any 1983-88 Cougar or Thunderbird.

It is entirely possible that the front track is indeed wider than the published numbers on 1987-88 cars. The numbers are probably wrong. When you take the same wheel (say, for the sake of argument, a 15" turbine wheel) and put it on a 1986 and a 1987, you can easily see the difference in track width, as the 1986 will have the wheel tucked under the fender, and the 1987 will have the wheel flush or even sticking out from the fender. I have always felt that the published numbers for 1987-88 cars were not correct because of the real-world known differences in the suspension and A-arms. Shawn's point is valid and indeed, that could be very true. We'll never know until someone makes measurements between them. For the time being, though, I'm going to go ahead and disagree with the published numbers.

Edit: One more thing about the track width published numbers...those may have been made using the standard 14" steel wheels (with or without the chrome spoke hubcaps). Those skinny ol' spokies are going to be tucked under the car, regardless of K-member. When you get to a wider rim, such as the 7"-wide turbines, the differences are very obvious.

differances in "K" members

Reply #20 – December 01, 2005, 04:56:37 PM

I'll make some measurements (control arm mounting width) when I have the time. That is about the only thing I can measure accurately while the k-member is bolted up.

Would anybody be willing to give me an old stock k-member? I'd pay for shipping. It'd be nice to actually know the differences rather than having vague recollections.

differances in "K" members

Reply #21 – December 01, 2005, 07:37:22 PM

awesome info guys...thank you!...all i have available is my stock tbird k. ill measure it up tonight if i can get it in the garage. im not entirely sure they will be able to move the a arm mounting points in for me. im going to be running a 17X8" rim and i would like it to fit just inside the fender the fender if at all possible whyle using the cobra arms i have on the way. i could have the fenders rolled as an option but outside of that ill be stuck. sticking out something like an inch wouldnt be any good...ive also got bullit springs on the way so the car will be lowered as well. hopefully everything works okay together...thanks again guys....

differances in "K" members

Reply #22 – December 04, 2005, 02:11:01 AM

Quote from: EricCoolCats

When you take the same wheel (say, for the sake of argument, a 15" turbine wheel) and put it on a 1986 and a 1987, you can easily see the difference in track width, as the 1986 will have the wheel tucked under the fender, and the 1987 will have the wheel flush or even sticking out from the fender.

Edit: One more thing about the track width published numbers...those may have been made using the standard 14" steel wheels...a wider rim, such as the 7"-wide turbines, the differences are very obvious.

Well I did just that on my '88 'Bird and they certainly do not stick out flush or past the fenders, in fact they tuck just as nice as the stock 14" steelies. In fact, the only time I've seen 7" wide rims stick out flush or past the fender was with the fox mustang k-member and t-bird control arms. I AM NOT trying to burn you...just not sure whether you meant measurements with tubular k or standard t-bird/coug k member.

I am assuming you're referring to the measurements of stock components. If not, then ignore a large part of this post.

differances in "K" members

Reply #23 – December 04, 2005, 07:59:52 AM

Quote

just not sure whether you meant measurements with tubular k or standard t-bird/coug k member.

I am assuming you're referring to the measurements of stock components. If not, then ignore a large part of this post.__________________

yeah. the tubular k member is originally made for a fox mustang, not a tbird. they will tweak one for me but im not sure how much. if they were desighned for a tbird id have no worries...im going to be running 17X8 with 03 cobra (same length as a tbird arm)a arms. im thinking if i can get them to bring them in to where the tbird ones are ill be alright. im sure thats going to be pretty involved. its not like moving a hole or motor mount or something....well see i guess...

differances in "K" members

Reply #24 – December 04, 2005, 04:59:38 PM

When I swapped to the Mustang K-member, All I had to do is ream the outer rear holes of the body mount location towards the outsides of the car when useing the Mustang bolt plate and didnt require any shims @ the spring perch. I used the T-bird control arms and find that the 16' Turbocoupe wheels sit flush if not out a hair from the fender lip. (I will probably swap in the Mustang contol arms next summer....just too bad i replaced the bushings and ball joints in the Bird arms)

As for engine location...No Idea as Bird was a Turbo 4cyl....BUT i can tell you the 5.0 sits exactly in the Bird as it did in the Mustang in reguards to spacing. As for height, it depends on which mounts you use.....I used new rubber GT mounts and find that the engine sits high (I am hoping they will settle a little).....you can goto the convertable mounts to lower the position if you like.

In Short, if you are able You can go look @ a 5.0 Mustang and take all the measurements you like to verify the spacing from the firewall and the radiator to the engine as well as any other concerns you may have.

Hope something in all that is of some help
Good luck
John

differances in "K" members

Reply #25 – December 04, 2005, 06:37:58 PM

i should still have my cars old k member behind the shed. its yours if ya want.

differances in "K" members

Reply #26 – December 27, 2005, 05:40:59 PM

well...i ordered the k member. its going too be a month though before i see it. that sucks a little. i was going too have them move the a arm mounting points inboared an inch on each side but it would have been way too much money for me because it would basically be a whole new custom unit. i figure ill roll the fenders, stay with a 245 on the 17-8 and see just how bad it ends up being. if i gotta go with the ghey fox mustang arms than such is life....

differances in "K" members

Reply #27 – December 28, 2005, 03:44:17 PM

oh, and by eyeballing the front control arm pivot points with a tape measure it looks like they are about 23 1/4 ish inches appart center to center....stock 88 tbird arms/k....

differances in "K" members

Reply #28 – December 28, 2005, 11:28:17 PM

Good threaD, thought I'd register and throw my two pennys in here for what its worth.

When I was swapping K-members on my 87 T/C to help facilitate the V8 and 5 lug swap I learned a few things, almost all of it the hard way meaning I actually did it. In any case heres what I got.

First, the 83-5 Bird/Cougar Kmember will bolt right into the later (87-8) cars but it WILL move the wheels outboard, ALOT. Especially using the longer 87-8 front A arms. Sooo, unless you like having your wheels stick out past the fenders or you plan on somehow widening or flaring the front fenders and doing something to make the rear match, dont do it. Also, the 87-8 Tbird (and 94-04 Mustang) A arms are 13 3/4" from the CL of the balljoint to the CL of the A arms mount swing axis (where it bolts to the K-member). The 93- older Mustangs (and 83-5 Tbirds) use a very similar appearing A arm but it is 13" from the same measurements described above.

Second, the 87-8 K-member has front control arm mount points that are about as narrow (width wise when viewed from the front of the car) as you are going to ever find in a Fox platform Kmember be it factory or aftermarket. I made this measurement off of 4 different factory Fox Kmembers, a 83-5 Tbird, a 92 Mustang GT, a 87 Tbird, and a 84 SVO Mustang and after calling almost every aftermarket Kmember manufacturer and tape measuring alot of them at Fun Ford Wknd events myself.

Third, since I was converting to 94-up Mustang 5 lug and brakes, and using 18x9 wheels that are fairly wide, and swapping to a V8, I knew that I was going to need a Kmember that kept the track width as narrow as possible. If i didnt, the front wheels were going to stick out of the fenders (unacceptable). The 94-up Mustang brake swap mandates using the newer spindles which also slightly increase the track width. It also requires using either the 94-up Mustang style ball joint or a spacer on the older 87-8 Tbird/Stang balljoint. Since my TurboCoupe was going to be lowered with the new suspension, I had to try to make sure that there was no contact between the tires and front fenders even on bumps (in other words, keep the wheels tucked inside the fenders with some room to spare)

Heres what I used:
1. Stock 87 Tbird Kmember modified as follows: Engine mount
perches cut off flush with K-member and replaced with engine
mount perches from a 92 Mustang Kmember so that the much
stronger 92-3 Mustang engine mounts could be used. The Stang
engine mount perches were welded in the same place as the now
removed Tbird perches. On the side of the K-member where the
upper spring perch is located (nearest to where the strut is, when
on the vehicle) there is a lip of fairly thick metal that will need to
be ground off. It is not structual or needed in any way and must
be removed to make clearance for the strut if you are doing what
I am. Nothing fun about grinding metal but its much easier off the
car the doing it after you have reinstalled the K in the car. No
other modifications to the K-member.

2. 92 Mustang A-arms with 94-up Mustang balljoints installed. ( I
used Moog balljoints available from NAPA) Using the shorter
Mustang A arms cut 3/4" of track width from each side. Doesnt
sound like much but its everything when you are putting 9" wide
SN95 wheels on the front of the 87 Tbird. Doing this will radically
change your camber. As in positive camber where the top of the
wheel will stick out and the bottom of the wheel will be tucked in.
The solution isnt a whole lot of fun but the payoff of having a
much wider front tire is worth it. I'll detail it later.

3. Maximum Motorsports caster/camber plates. 92 Mustang GT rack
and pinion with Baer racing tie rod ends. Russel braided stainless
front flex brake lines. Koni adjustable front struts (no longer using
factory adjustable suspension)

Hope this helps those people that are looking to swap engines or update their wheels/brakes to the 94-up Mustang GT/Cobra setups and the better wheel choices that such an upgrade allows. Remember the wider you go with on your front wheels the harder it will be to keep them from sticking out so you may or may not have to do some of the mods I listed above. Just my experience in having done it. Good luck.

differances in "K" members

Reply #29 – December 29, 2005, 01:04:54 PM

I put a D&D tubular k-member and a-arms in my 84 tbird and everything lined up just like factory. you will be glad you made the switch to tubular after the first time you pick it up and notice how light it is.