Suspension Mods..What to do?

[68poncho]

Hi, i got a few questions that i hope someone can help me get out of my mind.

As some may remember im restoring/modding a GTO, and i just got interested in modifying the suspension on this car, as i stated on another post i already have the following parts:

*1 1/4" Trans Am Front Swaybar
*`80 Trans Am Disc Brake setup
*`80 Trans Am Steering Box
*Unknown brand "lowering springs"(looks more like sagged originals)
*Energy Suspension rear control arm bushings

I don`t want to build a track car, just a fun cruiser that can keep up with the wife`s `02 WS6 on the twisties, i know it can be done on a budget(at least i hope), at first i was thinking about Hotchkis parts, but after reading some posts im not sure...

So right now this is sort of a wish list i have:

*BMR Front UCA designed for the f-body spindle
*BMR Front Springs(1" lowering)
*BMR Rear Springs(2" lowering)
*BMR or Hotchkis Rear swaybar(not sure on size yet)
*Polyurethane bushing all around


Now for the questions:

1.- What other mods do you recommend for my GTO?
2.- What shocks should i run, Bilsteins or Edelbrocks?
3.- What parts do you think i may need for the f-body spindle swap?
4.- Any input on BMR`s product quality?
5.- Since im taking the body off, should i box the frame?

As i said before, ANY info is welcome, just keep in mind the purpose i want to give this car... THANKS IN ADVANCE.

John.

[LowBuckX]

first things first Do the best brake system you can affford. I had factory discs and thought they where great till I did my $360 4 wheel big brake build and now I know how lacking the factory set-up is.

[Rod]

1.- What other mods do you recommend for my GTO?
2.- What shocks should i run, Bilsteins or Edelbrocks?
3.- What parts do you think i may need for the f-body spindle swap?
4.- Any input on BMR`s product quality?
5.- Since im taking the body off, should i box the frame?

WOW ok!
1. a four wheel disc brake setup power boosted, vacuum or hydra depends on you're budget
2. neither run and adjustable shock for a better tuneablity (yes even on the street) every bodies idea ride stiffness is different and you will be less disappointed that way
3. I'm sure a GTO website exist with that info
4. BMR's products seem to be of good quality (i just started putting some of there stuff on a shop car and will carry it soon if it stands up) I have heard just good stuff
5. yes box the frame add some gussets, ditch the poly bushings put in solid, no it wont stiffen the ride terribly, remember most new cars the frame is welded right to unibody, it just makes the suspension do its work

[6'9"Witha69]

+1 on the solid bushings, both body and LCA/UCA. As Rod stated it doesn't make the ride too harsh, in many ways the Poly stuff makes ride harshness worse due to bind. Make sure you can grease as many bushings as possible, including the sway bar pillow blocks.

Honestly, for a GTO, call Marcus @ SC&C http://www.scandc.com/
He has packages for every budget, and comes highly recommended for both knowledge and service.

Top it off with a budget minded brake system from someone like Kore3.
http://kore3.com/

[wmhjr]

I'd first ask where you live and where you're gonna be driving. I do NOT like solid body mount bushings on a street car. Around here, what they're good for is shortening the lifespan of your body work and giving you new squeaks and rattles every mile you drive.

Yes, SOME new cars don't have bushings. To say that MOST don't is maybe an overstatement. Most relatively high end cars do have isolator bushings. That includes some pretty highly regarded sports cars. Beyond that, those newer cars are engineered from the ground up to be different.

Just my 2 cents. There's a local guy with a '67 Chevelle that has solid mounts. He regrets using them every time he drives the car.

For some fitment advice you could try the performance years forums, however they really don't do much in the way of pro-touring over there. Just keep in mind that the idea of good handling over on PY is if you can turn out at the exit of the drag strip.

I would also question how poly bushings could make "ride harshness worse due to bind" over solid bushings. By their very definition, solid bushings would be completely "bound" at all times and obviously have less elasticity.

If you live on really smooth roads, no problem. Just remember it's a street car and you'll want to enjoy it.

[6'9"Witha69]

I would also question how poly bushings could make "ride harshness worse due to bind" over solid bushings. By their very definition, solid bushings would be completely "bound" at all times and obviously have less elasticity.

Poly is usually stuck and bound all the time. I have worked on quite a few cars, and over the years have learned to stay away from Poly. It is meant as a compromise between the compliancy of rubber and the lesser deflection of solid. Everything seems tight and easy to move for the first few months, but as the white grease dries out from the outer face the bushing starts to bind against the frame, adding resistance in bump AND droop, effectively incrersing spring rate and creating a harsher ride. The solid bushings articulate smoothly through bump and droop, creating a more linear effective spring rate.

Or you could have misunderstood my first post and are attributing the bind comments to body mount bushings.

[Roadbuster]

+1 on the solid bushings, both body and LCA/UCA. As Rod stated it doesn't make the ride too harsh, in many ways the Poly stuff makes ride harshness worse due to bind. Make sure you can grease as many bushings as possible, including the sway bar pillow blocks.

Honestly, for a GTO, call Marcus @ SC&C http://www.scandc.com/
He has packages for every budget, and comes highly recommended for both knowledge and service.

Top it off with a budget minded brake system from someone like Kore3.
http://kore3.com/

x2 on calling Marcus.

What condition are the current parts in? If it is anything like mine was I had to replace everything! Set aside some budget for the tie rods, center link, and idler arm. Just about every suspension redo will need those parts no matter whose parts you go with. Also look into replacing the rag joint with a new one or a universal joint.

Also the rear frame stiffeners really tighten up the back of the car.

Jon

[JRouche]

I'd first ask where you live and where you're gonna be driving. I do NOT like solid body mount bushings on a street car. Around here, what they're good for is shortening the lifespan of your body work and giving you new squeaks and rattles every mile you drive.

Yes, SOME new cars don't have bushings. To say that MOST don't is maybe an overstatement. Most relatively high end cars do have isolator bushings. That includes some pretty highly regarded sports cars. Beyond that, those newer cars are engineered from the ground up to be different.

Just my 2 cents. There's a local guy with a '67 Chevelle that has solid mounts. He regrets using them every time he drives the car.

For some fitment advice you could try the performance years forums, however they really don't do much in the way of pro-touring over there. Just keep in mind that the idea of good handling over on PY is if you can turn out at the exit of the drag strip.

I would also question how poly bushings could make "ride harshness worse due to bind" over solid bushings. By their very definition, solid bushings would be completely "bound" at all times and obviously have less elasticity.

If you live on really smooth roads, no problem. Just remember it's a street car and you'll want to enjoy it.

Good points....

Im not sure what the makeup of many new cars are. I imagine alot of them are uni- bodies so I would assume they dont have body bushings. But even with cars with body bushings I would leave them in. I dont imagine much gain is gotten for the possible loss in isolation. But most of my cars are uni-body so there isnt any rubber between the body and the frame, no frame.

Now for control arm bushings. I would stick with the stock rubber or go with delrin af. And even with the delrin af bushings that are teflon impregnated delrin I would still do what I do and drill and tap for zerks to grease them occasionally. Even though the delrin af doesnt need it.

Rubber bushings are the best IMO. They do exactly what they were built to do. But the rubber compounds used have too much rotational stiffness for some folks. But a properly set up suspension with rubber bushings is the best for a street car IMO.

Poly??? I dont think it should be used in control arms. It has durability, strength, and is mostly impervious to all the elements of the road. So why dont I like them?

I think poly was a quick fix for some guys that wanted more stiffness (control arm control) with the suspension. They are not a direct replacement for rubber bushings, even though they are marketed like they are. They dont operate the same way as a rubber bushing. I kinda think if they were used in place of the rubber exactly they might be better. But they are not.

Rubber bushings are bonded to metal sleeves so they dont rotate in the sleeve. And the metal sleeve is held tight to keep from rotating in the bore that they go in. So the rubber acts like two resistive loads.

One, that many folks dont like but it works is the rotational spring load that bonded rubber bushings have. The other is the fore and aft, up and down resistive load that the rubber provides. Thats the main resistance load that folks are trying to increase. Cause the soft rubber allows the control arms to move around and even a compression of the rubber by an 1/8" will allow the alignment to change alot during hard driving.

So here comes poly, not as compressible. So the control arms stay in place. But they are not bonded to the sleeves!!! So you have a new bearing (sliding) surface in rotation. So it needs to have some grease, cause poly is NOT a good bearing (sliding) material, pretty sticky. So they get greased on the install. Work great till the grease oils out and becomes dry. Then the friction starts. And we really know it when we hear it. Yep, the noise.

So I have done some poly bushings. But I always modify the housing for zerks grease fittings. And I always put a grease groove in either the bushing or the housing. A spiral grease groove that will grease the entire sliding surface.

Delrin bushings dont need the grease groove. Delrin AF really doesnt. But I dont think the makers of delrin bushings use delrin AF, its more expensive. But delrin is a superior plastic for bushings. And with Delrin AF the teflon really helps.

Im thinking I need to market some Delrin AF bushings LOL. IMO they are the best route to go with. JR

[wmhjr]

Poly is usually stuck and bound all the time. I have worked on quite a few cars, and over the years have learned to stay away from Poly. It is meant as a compromise between the compliancy of rubber and the lesser deflection of solid.


The solid bushings articulate smoothly through bump and droop, creating a more linear effective spring rate.

Or you could have misunderstood my first post and are attributing the bind comments to body mount bushings.

No, I think I did understand and just don't agree. I've used poly plenty of times. It's not possible for solid bushings to "articulate" smoother than poly. They don't articulate at all. That's the point. With solid bushings, you force the BODY to articulate. I do agree that the poly bushings are a compromise. That compromise is between the very quiet but compliant ride of rubber, and the very harsh and non-compliant performance of solid.

Another thing. If you're not doing a frame off but are just replacing bushings on a 60s car, solids can also result in your mounts themselves being destroyed.

60s A-Body cars were not designed to have so much tension applied to the body mount areas. After 50 yrs of wear, they're even less capable of sustaining that load. I know of one very nice Elky that the owner installed (over numerous objections) solid bushings and then after 1 year had to repair body mounts that got destroyed AFTER the car was painted. Roads are too rough here, and the combination of a stiff suspension, solid bushings, rough roads and 50 years of wear found the weakest point. The body mount. Even poly can provide just enough compliancy to prevent damage.

[wmhjr]

Good points....

Im not sure what the makeup of many new cars are. I imagine alot of them are uni- bodies so I would assume they dont have body bushings.

JR - agree with lots of your points.

A clarification. I find it interesting that so many people think that because new cars are often unibody, they don't have rubber body bushings. They usually do. It's just that the bushings are between the subframes and the body rather than between the body and a perimeter frame. Same thing. Just slightly different execution.

Some examples right of the top of my head:

Ford Taurus: Yep, the family mainstay is a unibody that has rubber bushings. There are solid aluminum replacements that some Taurus fans can buy on the aftermarket, but OEM is rubber.

Mercedes AMG E63: The $105K 500+hp german battleship has subframe bushings.

Just a couple examples of either end of the spectrum.