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Discussion Starter #1
My 87 Shelby z k-frame has a crack. I'm wondering if I should repair or upgrade. I keep hearing about 89 or 90 k-frames etc. What are the advantages of the newer k-frames/a-arms? There's an 89 lebaron t1 automatic at the wreckers I could pull the k-frame off of, but is that any improvement over what I have? I realize I'd have to re-weld the tranny bobble strut brace onto it.

Would a Caravan k-frame fit? There may be a mini-van I could grab a k-frame off of.

Let me know my options and what I should go with.
 

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suposedly the 89-90 controls wheel hop better with the rear piviot instead of the stub strut at the back mounting point of the control arm
though the whole K frame looks less ridged to me - the 89-90 is kinda hollow lookin from the bottom

your shelby sway bar will fit - use it it's better & bigger

also just read the other day the 89-90 puts more of the car's weight on the springs - the stub strut on the 87 carries some of the weight

don't think the van one would fit
 

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van one won't fit. The dual pivot kmember is actually stronger than the early k. You'll notice if you drop both on the ground, and one you get the later k in the car it just feels a bit more rigid. Some of that could be that the dual pivot doesn't exert a twisting force on the kframe and chassis like the stub strut will.

89/90 lets you use your current sway bar and spindles with no issues of geometry changes. Also Energy Suspension makes poly bushings for the 89/90 arms as of about 3 years ago, they're superior and cheaper than any other poly bushing out there.
 

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I got an extra and have been thinking it is time to bust out my band saw I've never used and make a dual pivot L body K member lol.

I am beginning to think it is pretty easy to break the old ones in a G body lol. It isn't that uncommon
 

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Discussion Starter #6
Okay, so it sounds like the 89 lebaron K-frame will work and I can re-use my control arms?

In the future what needs to be done to upgrade to the 11" front brakes? control arms/spindles/calipers/caliper brackets/rotors/pads?
 

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you mean the 87 control arms ?
no they won't fit - the mount for the control arms changes at the back from a strut -or stud if you well , to a piviot like at the front of the arm - that's the advantage of the 89-90 style

the back of the 87 works like a lever in the bushing prying it up and down whereas the 89-90 has the piviot that allows a more fluid motion in the suspension

it's the deformation of the bushing on the 87 that contributes to the wheel hop

mo perf used to have a stiffer bushing but I could never find those

to do the brake upgrade you'll need the knuckles with the brakes
not sure if you need to change the struts - mount point to knuckle might be diff but I'm not sure on that

consider upgradeing to the 89 rear disc too - you'll eliminate the back out screw for the caliper piston that's usually seized if you do - then you won't need calipers every time you want to do the back brakes
and you'll loose the hokey parking brake deal on the caliper too as the 89's &^ use a mini drum brake inside the rotor for the parking brake
 

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that one is going up on the fridge lol
 

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Discussion Starter #11
I was actually on the polybushing site and I could see the differences. So 89 K-frame with control arms. Are the 89 big brake spindles specific to those brake packages (ie they made two different type of spindles in 89 - one for regular cars and ones for big brake cars)? Just wondering what I should pull if I'm taking the 89 lebaron k-frame from the wreckers.

I already did the newer vented rear brake upgrade many years ago as I had an 88 Shelby Z donor car that I stripped a while ago and took those brakes.
 

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if the baron dosent have the big brakes leave the spindles ( knuckels) behind and scoop those with the brakes when you find them later

pretty sure the caliper mounts are diff for the big ones

for now you can get away easy with the struts and brakes in the 87 - won't need to do more then pull the ball joint stud out of them and let em hang while the new K frame and arms go in
 

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89/90 11" brakes use a molded in caliper bracket. Not a bolt on like the other cars.

88 ShelbyZ's didn't have vented rear brakes. only 89+ cars. But if you got vented rears I hope you got the MC and the prop valve as well. You'll need those to run a proper working setup.

As the Doc said you need the kframe and control arms. Your stock spindles and sway bar bolt right in.


Doc, you couldn't find MP stub strut bushings? We ordered them from the dealer back in 98. Not sure when you were looking for them. I'd rather get ES bushings for either the stub strut or the 89/90 kmember setup.
 

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Discussion Starter #15
89/90 11" brakes use a molded in caliper bracket. Not a bolt on like the other cars.

88 ShelbyZ's didn't have vented rear brakes. only 89+ cars. But if you got vented rears I hope you got the MC and the prop valve as well. You'll need those to run a proper working setup.

As the Doc said you need the kframe and control arms. Your stock spindles and sway bar bolt right in.


Doc, you couldn't find MP stub strut bushings? We ordered them from the dealer back in 98. Not sure when you were looking for them. I'd rather get ES bushings for either the stub strut or the 89/90 kmember setup.
Well I guess the car I parted was an 89, but I swear it was an 88 Shelby Z as the car had the 87/88 body mouldings (89's changed did they not)? Regardless I got the vented rears with the internal drum e-brake setup. I did not swap the prop valve or the MC (my 87 shelby Z already had 4 wheel disks just the older rear setup) so I figured no other changes were necessary.
 

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sounds like ya might have striped the brakes from an 89 CS

it would have the body side moldings but no areo kit

prop valve wouldn't make a diff either way
rear disc cars tend to get tail happy in panic stops

both my 87 shelby z and the 86 turbo z have the same problem
turbo z still has the drum prop valve

I did read somthing about newer cars haveing a prop valve with a yellow tag that is supposed to solve this - but I think those cars would also have the bigger front brakes

I still think the bigger front brakes may be the solution to this as increaseing the grab at the front should act to ballance out the excessive grab at the back discs
 

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Discussion Starter #17
I don't think it was a CS as it had a full shelby z body kit (front lower bumper kit, rear spoiler, fiberglass door panel kit, side plastic mouldings, intercooler, t2 turbo etc.) Anyways, doesn't matter. I have never really noticed any braking issues with the rear vented disks, but then again I don't rally race or do any emergency brake stops to really test it out. Lately I've noticed some uneven braking when braking hard (I think one side is grabbing harder than the other) perhaps one of the calipers is sticking a bit, but it's to be expected as I haven't driven much in the last 3 years. It was only out once last year and zero times the year before so things seize up if you don't use them.
 

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My new yorker has full 11" setups with the MC and prop valve from an R/T The car stops hard and fast and just barely locks the rears under about 2mph just as you come to a stop. I just about knocked the wind out of my sister doing a panic stop from 35MPH in about 20ft or less.
 

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Discussion Starter #19
Finally got around to pulling that subframe. Went quite smoothly to tell you the truth considering it's a 20+ year old part. Time to clean it up, paint it, polybushings throughout and back it goes.
 

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there are 3 different k frame types. there is the early rear stub single pivot with stamped steel arms. 87 and older. 88-89 have stamped steel dual pivot arms. those use the same front ball joint in the arms and your existing spindle and brakes will bolt right on. that type will lower the front of the car about 1 inch.it gives the car a nice lightly raked stance.
the 3rd type is 90 up which is dual pivot cast aluminum arms. those bolted on the pre 90 will cause the caster angle to change. its like a 23 or 24 degree change and thats not good, makes alignment almost impossible. most of the 90 up vehicles hae the shock tower placed in a slightly different position to accomodate the different strut mounting point.
 
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