Good suspension setup?

[Beast_TR]

I am going to be doing some extensive mods to my 87 GN when I get back to the states (currently on a 1 year tour in Korea) and had some ideas as to what I want to do to my cars suspension to help it handle the added power as well as making it more fun to drive on the street. I am looking to add a "ATR" bar from fullthrottlespeed, UMI upper and lower rear control arms, and poly bushing. I already have Kirbans rear springs and Bilstien shocks in the rear only but will be adding some to the front as well. I have heard of people adding the braces (both front and rear seat) as well, I have been holding off on those as I have heard that they are not need so much on a hardtop car. Any suggestions would be nice, thanks for your guys time.

 

[bruce]

I am going to be doing some extensive mods to my 87 GN when I get back to the states (currently on a 1 year tour in Korea) and had some ideas as to what I want to do to my cars suspension to help it handle the added power as well as making it more fun to drive on the street. I am looking to add a "ATR" bar from fullthrottlespeed, UMI upper and lower rear control arms, and poly bushing. I already have Kirbans rear springs and Bilstien shocks in the rear only but will be adding some to the front as well. I have heard of people adding the braces (both front and rear seat) as well, I have been holding off on those as I have heard that they are not need so much on a hardtop car. Any suggestions would be nice, thanks for your guys time.

You want the HR Parts n Stuff rear bar. For road use the ATR *binds* the rear suspension too much.

Nope, you all the braces, and polyurethane body bushings.

 

[sailbrd]

For a street car do not use poly bushings on your control arms.

 

[Not Avg 6]

Definitely, get all the braces. I have the exact setup you describing except I have KYB's and added the GNX bushings. I'm very happy and it was'nt that expensive.

 

[Gary Wells]

I think that all of the kirbans bracing, even on a solid roof car, is a good idea. With more hp & tq, you need tha rear seat brace as a minimum. I currently have Bilsteins on the car now, and have Kirbans rear and front springs, missing #s 3 & 4 lower & GNX upper bushings, and the other brace sets going on the car asap. I think that the rear seat braces decrease or avoid the normal amount of cracking behind the front windows upper corners. Even with stock HP & tq, a car without the rear seat braces will seperate up there in time. Just depends on how many stoplight races you come across.

 

[Gbodyolds]

I personally would not use poly bushings they bind, make noise and they are too hard I had them in my last car and did not like them. I do use poly body bushings on the other hand I just cover them to death with synthetic grease to prevent them from making noise. I would recommend the heavy duty high durometer moog bushings the upper a-arm # is K6411 (that does both sides) the lower # is K6421 (that does both sides as well).
one thing you might like to consider for the front is the SCandC stage 2 kit which is what I'm leaning toward (www.SCandC.com)
They describe it as
"The secret is the combination of the tall ball joint and adj. upper arms which markedly improves the camber curves and relocates the roll center. This means more grip and less body lean.

For cars that include a tall lower ball joint it further improves the camber curves and roll center height for even better handling. It also lowers the car .5”-.75” and moves the spindle and steering arm to a more favorable height radically improving the bumpsteer.

For drag racing it minimizes toe change under hard acceleration reducing drag and making the car much more stable on the top end. It can also allow more suspension droop for greater weight transfer and better launches."

I have all the kirban braces except the seat brace which I will be getting
my rear suspension has hotchkis springs, bilsteins, hotchkis lowers and edelbrock uppers with an ATR bar, I love it BUT with everything I have read I am considering an upgrade to the H&R bar, my front has moog 5660 springs, bilsteins, heavy duty moog bushings, 36 mm sway bar and an XH steering box with 245/50/16's all around. the handling difference from stock is remarkable, but like I said I am considering the H&R rear bar and the SCandC stage 2 kit to further improve the handling

a lot of people will tell you that you cant make a G-body handle that's bull $hit there was a mag article about a GM built G body called the FE3X that did 1G on the skid pad
all it had was
255/50/16's, 700 lb/in front springs, koni adjustable's, 1.5" front bar, urethane bushings, stock front brakes, fast ratio box, 3/4" rear bar and f-body rear disc's
a lot of us that like handling have a lot more than this in to our suspensions, could you imagine what they can do on the skid pad with a pro driver?

 

[bruce]

I personally would not use poly bushings they bind, make noise and they are too hard I had them in my last car and did not like them.
I do use poly body bushings on the other hand I just cover them to death with synthetic grease to prevent them from making noise.

"The secret is the combination of the tall ball joint and adj. upper arms which markedly improves the camber curves and relocates the roll center. This means more grip and less body lean.

IMO, the trick to using poly suspension bushings is to clearance them so that the suspension is bind-free when installed. Generally, they come as being press fits, and once you tighten everything down, they bind up the suspension. According to some texts, the oem rubber bushings add 25-50 ft/lb of spring rate, FWIW. IMO, the ideal suspension moves freely, and the springs and shocks deal with the related motion/ dampening. For them to handle those loads, means everthing else must be free to move.

With the lower front arm carrying the spring loads, and to isolate some of the road noise out of the car, I just have the oem lower bushings, and then the PolePosition Uppers.


Do you have a Moog part no for the taller lower Ball Joint?.

 

[Gbodyolds]

I don't know a moog part # for a tall lower ball joint from everything I have read people are using a truck ball joint as a tall ball joint the problem with that is that it will work but it doesn't quite fit the spindle correctly to get it to fit right you would have to ream the spindle hole but at that point you just took away most if not all or the advantage of the tall ball joint.
the tall ball joints sold by SCandC are made by Howe racing and they are of a "modular" design meaning they can be rebuilt and customized for your vehicle by taking them apart and changing the ball stud, when bought from SCandC they are pre assembled with the right ball stud to correct a lot of the incorrect geometry found in a stock G-body suspension. I think the arms sold in the stage 2 kit may be Pole Position parts if they are in fact you could probably have a killer setup with just the addition of their ball joints. I do not have the stage 2 kit yet (but I will have it) so what I am telling you is only being said from what I read and been told not actual experience.

I have read somewhere about clearance the poly bushings I never tried it but it would be interesting if it worked, I have drilled a hole in them and screwed a zerk fitting in to them to grease them which works pretty good and eliminates a lot of squeek.

 

[bruce]

I have read somewhere about clearance the poly bushings I never tried it but it would be interesting if it worked, I have drilled a hole in them and screwed a zerk fitting in to them to grease them which works pretty good and eliminates a lot of squeek.

Gotcha.

It works, ie clearancing the bushings.
I always weld on a 1/4" nut, drill it thur, and then thread in a zert fitting.

FWIW, I have the GW rear lower arms with the Heim/Poly set up, and it really allows for noticeable difference in ride.

 

[bishir]

Jeff when ya getting back? Maybe I'll have mine done by then.

 

[Gary Wells]

Gbodyolds:
............................. duty moog bushings, 36 mm sway bar and an XH steering box with 245/50/16's all around.......................
----------------------------------
What's a XH steering box?
Is this a Saginaw box?
Have you seen this swap done before and know the results?

 

[Gbodyolds]

An XH box is a fast ratio box and is a direct replacment it comes out of a third gen trans am with the WS6 option im sure it can come out of other cars as well but this is what i know it comes out of.

 

[Gary Wells]

What years is the third gen Trans Am, and thank you for the info.

 

[Gbodyolds]

it was about 84 or so to 92 the I-ROC camaro may have the XH box too but im not 100% on that

 

[disco stu]

Gotcha.


FWIW, I have the GW rear lower arms with the Heim/Poly set up, and it really allows for noticeable difference in ride.

Yep, me too (with the Del alum bushings on the other side). With Edelrock uppers which also have a large heim type, "johnny" joint on one end and Poly on the other. NO bind. No noise.

Global Wests are more expensive, but good quality.

 

[GNVAIR]

An XH code box is the steering box used on the 85-92 F bodies with 16" wheels. GM used codes to designate the boxes. The XH has no difference in ratio. The big difference was the internal stops that limited the travel on the box so the wider 16" tires wouldnt rub the sway bar and inner fenders. No other internal difference on that box. A lot of people on the Monte SS site made a big deal about this box, but it offers no performance or drivability improvement over the stock fast ratio box used on the 83-88 performance G bodies.

 

[Gary Wells]

Thanks for the responses regarding the steering box. Now I know.