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post #1 of 18 Old 09-03-2011, 02:29 PM Thread Starter
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Help an idiot sort his suspension combo.

This is going into my 1991GT Mustang. The car has 0 options from the factory, so is quite light compared to other GTs. Full length subframe connectors/jacking rails/rocker triangulation braces/seat pan brace/driveshaft safety loop are all going in this coming weekend. What I have in parts so far:

Front:
Maximun Motorsports tubular k-member/G-load brace
AJE SN95 length tubular A-arms with spring perches
Steeda X2 ball joints for the AJE arms
AJE upper spring perches for the K-member
Steeda caster/camber plates
Steeda SN95 bumpsteer kit
.250" milled bosses on my steering rack
Racecraft SN95 2" drop spindles
M-2300-K brakes
Tokico Illumina struts
Heavy duty steering shaft with heavy duty rag joint
Engine set back 1" and down 3/4"
Stock GT sway bar
Energy suspension sway bar bushings/endlinks
3-point strut tower brace/firewall brace

Rear:
Mathis anti-squat mod (1&1/2" lengthening) on the rear lower control arm mounts
Aluminum FRPP diff girdle/ARP cap studs
Steeda Weight-Jacker lower control arms
Evolution Motorsport 3-link
Fays2 Watts Link
M-2300-K brakes with Fox axles/North Race Car brackets
Tokico Illumina shocks
Stock (for the moment) rear sway bar

Car sits 1&3/4" lower than stock right now, and I would like to keep it there. Note I didn't mention springs; this is where I REALLY need your help and advice (although, any input you have on the rest of my parts pile will also be greatly appreciated). What do you believe would be my best bet for springs, to both handle the increases roll in the rear from the 3-link and maintain the lowered stance/street manners (as the car is my all-around daily driver)? Also, sway bar diameter; any thoughts and/or suggestions.

I have spent the better part of my weekend searching here for info; I found quite a bit of useful info but am still lost on this. Thanks for the replies.


"Speed doesn't kill people, stupid people who can't handle speed kill people."

Last edited by 86GT2go; 09-03-2011 at 03:13 PM.
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post #2 of 18 Old 09-03-2011, 07:04 PM
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Quote:
Originally Posted by 86GT2go View Post
Steeda SN95 bumpsteer kit
Tokico Illumina struts
3-point strut tower brace/firewall brace

Rear:
Mathis anti-squat mod (1&1/2" lengthening) on the rear lower control arm mounts
Evolution Motorsport 3-link
Fays2 Watts Link
Tokico Illumina shocks
First thing I noticed is that you are spending a lot of money to not go with coilovers at the same time. Ditch the Tokicos and get some real shocks (Konis, Bilsteins, ASTs). Front conventional spring rate recommendation: 750ish (I used to have 1000 lb/in on the front of my car and it was brutal). Rear springs rates should probably be conventional 400#+ torque arm spring rates. Why the Mathis anti-squat brackets with the 3-link and Watts link? Have you done the math to figure out that your anti-squat would be too low? Too much anti-squat is just as bad as not enough. Also, the SN95 bumpsteer kit may not work unless you have changed out the steering rack. SN95s used a different thread pitch for the tie rod stuff, iirc. Someone here can correct me if I am wrong on that. Ditch the strut tower brace. With all the other bracing, you don't need it and it just gets in the way of working on stuff in the engine bay (plus it's weight that is up high and towards the front).

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post #3 of 18 Old 09-04-2011, 03:35 AM Thread Starter
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Thanks for the reply, and your honest opinion (both of which I need). Correct me if I am wrong, but niether the Watts Link nor the 3-Link have any real changing effect on anti-squat (as the Watts can control side-to-side movement and be used to dial in roll center while the 3-Link adds axle compliance and ease-of-rotation over rough surfaces/uneven pavement). The car will still need some anti-squat dialed in, and considering that I have the car lowered 1&3/4" it takes away from the already poor anti-squat in the rear. By moving my pick-up points down the 1&1/2", I can regain some of the anti-squat lost by lowering.
The reason I am not going coil-over (at this time) is front rim-to-strut clearance will be tight as it is. Any more bulk form the strut will likely interfere with the wheel.
Tokico Illuminas won't be enough to control my required spring rates, huh? Bummer as they are new-still-in-the-boxes. Could you suggest a certain series of shock/strut that would work (I see you mentioned Koni and Bilstien, perhaps I should give them a call and talk to them about what I have/am planning).
Thanks again for your honest input. Anyone else have any input on my junk?

"Speed doesn't kill people, stupid people who can't handle speed kill people."
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post #4 of 18 Old 09-04-2011, 09:17 AM
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Be careful how you go about dialing in anti-squat, because when you alter the side view inclinations of the LCAs you are also altering the axle roll steer effect. Generally, lowering the axle side pivots results in a shift toward, and possibly into, oversteer. There is a tiny roll center height change due to LCA orientation because the PHB or WL cannot lie precisely on the rear axle line.

With a 3-link, you can alter the A/S without screwing up the rollsteer by playing with the inclination of the upper. I'd (roughly) set the RC with the PHB/WL, then set the rollsteer with the LCAs and then tune the A/S with the UCA.


Ditto on the dampers - I have Illuminas on two other cars (little else above the OE replacement level being available), and they ride more harshly than they should for the control that they offer. I would expect that the same design team was involved with the entire Illumina line and that they would have continued to think inside the same box when it came time to do the valving for the aftermarket Fox pieces.


Norm

Mine: '08 GT, 5MT, black/light graphite, un-Fstock (DD, occasional track day)
Wife's: '10 Legacy 2.5GT (DD, six-speed manual)
Spare:'01 20AE Maxima, 5MT (also my bad weather alternate)
Various Loose Parts: '79 Malibu

Last edited by Norm Peterson; 09-04-2011 at 09:20 AM.
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post #5 of 18 Old 09-05-2011, 06:39 PM Thread Starter
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Thanks Norm, and I think I get what you are saying about anti-squat. Being that I have the weight-jackers, do you think I could still do the Mathis mod, but drill 2 or 3 sets of holes in the bracket to help set anti-squat initially, then use the jacking of the arms to fine tune it? Being my upper link only has an adjustment for length (to set pinion angle, all adjustments to anti-squat will have to come from the lower control arms/attachment points to the rear axle.

I will give Bilstien or Koni a call on my days off and see what they would recommend for damper rates.

Thanks guys, and keep the comments/info coming. I do not want to put a car together that I will be unhappy with. This is my daily driver/project car/HPDE car and I am asking a lot of questions so that it can do admirably at all 3 tasks (even if the driver sucks ass!).

"Speed doesn't kill people, stupid people who can't handle speed kill people."
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post #6 of 18 Old 09-07-2011, 06:11 PM Thread Starter
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Any more thoughts, guys? This car will be going down for the winter and I will be performing most of the chassis swap-over then, along with rebuilding the engine/tranny.

The rims/tires I will be using are 18"x8.5" front with a 245/40-18" tire, rear are 18"x10" with a 295/30-18" tire. Quad shocks will be eliminated at the same time the Watts/Tri-link go in. Fender lips will be rolled/pushed just a hair to get the clearance I need. Same with the inner wheelhouse areas, worked for some clearance. I have FOX length axles and the M-2300-K brakes. Front fenders already have a slight roll in their lips (guy before me did it), but I will be further rolling/pushing them as needed.

Help me out; I don't know a whole lot about this suspension set-up stuff and am asking the more knowledgeable so that I can learn (beyond just book-learning and theory) and properly set up my car.

"Speed doesn't kill people, stupid people who can't handle speed kill people."
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post #7 of 18 Old 09-07-2011, 06:58 PM
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That's an awful lot of tire size stagger - it will tend to make for heavier understeer.


(I haven't forgotten about the other post)

Norm

Mine: '08 GT, 5MT, black/light graphite, un-Fstock (DD, occasional track day)
Wife's: '10 Legacy 2.5GT (DD, six-speed manual)
Spare:'01 20AE Maxima, 5MT (also my bad weather alternate)
Various Loose Parts: '79 Malibu
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post #8 of 18 Old 09-08-2011, 12:13 AM Thread Starter
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I was also thinking of a 255/35 series up front. I already have a set of 275/35s sitting on a second set of 10" rears, so I will try to dial the car in on these. Like I said, this will be my winter upgrade for this car, and I am wanting honest thoughts as to what I am doing wrong/could do better. From late spring until middle fall, this car is daily driven. I have my truck for cold/snow/ugly weather duty. The 245/40 and the 295/30s will be my driver tires, I have a set of 94GT Tri-bars with 245/45s all the way for 'spirited' driving duties.

Norm, thank you for the info you have provided so far. I have already put the Illuminas up for sale (as well as another set of SN95 KYB AGXs) and the FOX Steeda sport springs (as they will not be enough spring for this combo). I am now in the hunt for some good springs and struts/shocks based on what you two have told me so far.

"Speed doesn't kill people, stupid people who can't handle speed kill people."
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post #9 of 18 Old 09-08-2011, 08:53 AM
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I also run a fays2 with a EVM 3-link. I removed my HPM lca mounts when I installed this. From memory it seems like the EVM was around 90% AS without relocating the rear lca mount. I did not use my drop spindles with my MM k-member as I do not believe you can get a good bumpsteer number with that setup (per Jack Hidley)
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post #10 of 18 Old 09-08-2011, 08:55 AM
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Oh and the EVM does have AS adjustment

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post #11 of 18 Old 09-08-2011, 12:31 PM Thread Starter
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Thanks for the info, CSG. I know the 3-link is adjustable for length, but did not realize it was adjustable for anti-squat too (unless length adjustment is anti-squat adjustment as well). What all did you notice about your car when you installed the 3-link and the Watts Link? I know rough theory of what to expect, but how did the car behave in the real world?

Thank you guys, helping me sort my junk will lead to a happy Mustang (as I won't constantly be fiddling with it).

"Speed doesn't kill people, stupid people who can't handle speed kill people."

Last edited by 86GT2go; 09-08-2011 at 12:37 PM.
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post #12 of 18 Old 09-08-2011, 01:28 PM
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There is a small amount of vertical adjustment at the rear mount. Although mine would hit if I put it at the bottom, I still ended up with a small amount of adjustability.
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post #13 of 18 Old 09-08-2011, 01:32 PM
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I have only driven around 30 miles with the setup and personally do not feel like the "quadrabind" setup really acts up during street driving so I don't expect much gain on this street car with the 3-link/watts. My car rides well and handles MUCH better than I will ever take advantage of on the street. Handles better then my "race car". I run 275lb/in front coilovers on Koni DA's and 200lb/in rear coilovers on Koni SA's. Full MM front end. I see no need for stiffer springs on a street car.
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post #14 of 18 Old 09-14-2011, 09:32 AM Thread Starter
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Thanks CSG. I am getting around to assembling the 3-link on my 1991 Lincoln MKVII LSC rear-end housing. I am also getting the Watts bar stand-offs on the rear-end today, along with finishing the install of a completely rebuilt (alternate stack method used) Trac-Lok unit, and 1994 Cobra axles/brakes. I will have to bend up some brake lines to clear the 3-Link bridge/Watts towers though.

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post #15 of 18 Old 09-14-2011, 09:55 AM
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Wait, you're using 8.5" wide wheels with 245 or 255 tires and are worried about front wheel to spring clearance on coilovers? I have 9" wheels with 275/40 tires on my '91 and I don't have any clearance issues. Granted, I am using a 17" wheel instead of an 18" but the wheel/tire are both at level with parts of the spring and I have no issues. Are you running some crazy offset? If you were I'd imagine you'd have other clearancing issues too like rubbing on near full lock turns which makes the DDing the car not real fun.

I can tell you from experience, coilovers with better control than conventionals will also give you a much better ride and tunability.

Last edited by MJ91GT; 09-14-2011 at 10:24 AM.
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post #16 of 18 Old 09-14-2011, 03:10 PM Thread Starter
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Right now, the car has 17"x8" wheels with 245-45s and the rim will rub on stock arms going into full-lock. I have 96 Cobras hooked to 94 spindles on FOX arms and dropped almost 2". The only problem I have now is the rub-close-to-lock. I know that the tubulars will give me some needed turning clearance. The wheels I will be putting on when I swap the suspension over are SN95-style 18"x8.5", with the extra .5" to the inside. I will be hooking them to the Racecraft 2" SN95 drop spindle and either running FOX-length a-arms (because I already have them) or getting the mentioned SN95-length arms. I wanted to keep the conventional front spring location as it will be inside the rims turn radius and allow me to run the wider wheel with the deeper backspacing without hitting the coil-over. I can do some more measuring, but trying to stuff all of this under the front fender will be a mechanical juggling act. THESE are the reasons I asked for everyones' opinions/real-world experiences. I am glad for the ones that have answered, but am somewhat let down by the low comment/experience sharing this thread has generated.

I may just bite it and order a full coil-over set anyway, and do a slight mini-tub in the rear to better tuck the wheels/tires. I still want to retain my interior plastics, so with careful axle/brake selection, I should be able to get the 18"x10" wheel with some nice meats to be streetable.

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post #17 of 18 Old 09-14-2011, 03:44 PM
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FWIW, I'm running sn95 a-arms on my 86. These expand my front track by 2.5" over stock but only 1.5" wider than the equivalent 87-93 v8 car due to the 86's narrower k-member a-arm pick-ups. I run MM's C/O for Bilsteins and a stock 96 Cobra 17x8" wheel. There are no C/O or a-arm clearance issues at full lock at my ride height of 25.5" ground to lip (however, the arms are the later design with more back-sde clearance built-in). this extra front track reduces understeer tendancies. I'm running a PM3L with MM PHB in the rear with other MM supporting pieces. This rear set-up made a huge difference in how the rear articualtes and rides (ride was 100% better except for a little gear noise transmitted into the cabin). Rear traction is greatly improved. I also added .5" spacers on Fox length axles which helped control oversteer. In combination, the front and rear work very well together with a neutral feel in A/X and agressive street driving.
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post #18 of 18 Old 09-14-2011, 06:05 PM
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My experiences are short here but I have tried a few different combos on my car.

I have '00 GT 17X8s that I run the street tires on. They rubbed before full lock with conventional springs (lowered 1.5") and stock control arms/k-member. I also have the R58 17X9 1995 Cobra R wheels, they also rubbed with the stock setup (lowered 1.5"). I even had the S197 17X8 stock wheels that are offset deeper inside the wells, they fit and worked but rubbed just a bit more on the control arm and inner fender on hard turns than the other wheels with the same setup as above.

I sold off the S197 wheels before buying my MM stuff so I have no experience with the combination. I can tell you that the 17X8 SN95 wheels and the R58 Cobra R wheels have zero contact to anything up front now. I did roll the fender lip and did the fender stretch on the front (though I really don't think I needed it for wheel clearance, it looks cool and it moves the air around the wheel instead of into it). I also have the different offset rear Cobra Rs (M179, I think). I accidentally put those on the front once, they did contact the spring.

My front setup is as follows:

MM k-member
MM fox arms standard offset- mounted in higher position (for 2" and more drop)
MM bilstein sport struts/10" 400lb hypercoil springs
MM swaybar mount reinforcement braces
MM aluminum rack bushings
AGR rack
MM bumpsteer kit
MM solid steering shaft
'96 and up spindles
Toyo RA1 275/40/17 tires
1995 Cobra R (FRPP R58) 17X9 wheels up front

The car's ride height is 2" lower than stock.

I've actually had much more issue with rear clearance than front, I think I've mostly resolved that, I'll know more on Saturday at the track.

I have no idea what those drop spindles are going to do to your wheel placement, I have no experience but I'm not so sure they're a good idea with an MM k-member since they specifically recommend the '96 and up spindles and the k has provisions to lower the car with a-arm placement.

There's a million 18" wheels that will fit with the MM setup, if the wheels you own are that close, I'd sell them off and look for some others that will work better. I'm assuming the wheels you have are S197 wheels? They were offered in 18X8.5 with more offset. Either way, if they are offset .5" more inside, you may still make it. My M179 wheel is half an inch wider than yours and was also offset about .5" more than my R58 wheels, they only made contact when the car was lowered onto the wheels (didn't make contact when the car was raised). Also don't forget many aftermarket struts are slotted so you can adjust it's placement, otherwise you can slot them yourself. Unless you're in absolute love with your wheels, I'd be ready to divorce them if they don't work and get something that does. You can probably sell them off to one guy and buy another set for the same price that will work for you from another. You'll hate not having coilovers IMHO.

Last edited by MJ91GT; 09-14-2011 at 06:09 PM.
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