The bushing survey...

[MAP]

Greetings folks,

I've not visited turbobuick.com in quite some time; nice to see that there's a new forum specifically devoted to chassis, brakes, and suspension!

On to the topic at hand:

There have been many great discussions here about bushings for the suspension and body/frame. I'd like to survey you folks for two very specifically opposite bushing schemes: first, hard bushings in the suspension but soft bushings between the body and frame; and second, the opposite: soft bushings in the suspension, but hard bushings (or better, a completely solid coupling) between the body and frame.

Polyurethane really falls close to the middle between a hard and soft material, IMO. If it's in the suspension, it can be counted as a hard bushing. If it's between the body and frame, I'd disqualify it completely for the purpose of this survey.

If your ride qualifies according to one of these extremes, then please describe, briefly, 1.) the overall suspension condition (e.g., sagging springs? loose front end?) of the car prior to modification, and 2.) the current condition and bushing configuration of the car. Include tire, spring, and shock information before and after modification.

Then please rate the following metrics before and after modification:

A.) Ride smoothness: 1=tooth-jarring, bare rims ride; 10 = 1973 Cadillac "I don't feel the road" boatiness.

B.) Steering stability over abrupt, jarring bumps: 1 = no effect; 10 = spontaneous lane changes.

C.) Handling predictability when pushed near extremes of traction in a turn: 1 = it tracks like it's on rails; 10 = what zip code are we supposed to be in?

D.) Rear-axle wheel hop in a straight line, if car can break traction in the rear: 1 = no hop; 10 = boing, boing, boing...

E.) Overall sense of "connectiveness" between driver and road: 1 = Vulcan mind meld; 10 = 1973 Cadillac "Road? What road?"

Thanks for taking the survey!

Best,
MAP

PS: This survey was started a little earlier over at: montecarloss.com >rolling chassis, if you'd like to see other responses from G-body owners.

 

[BJM]

Complete replacement of all front bushings with new stock style rubber. Used MOOG 5660 front springs (400 lb/in went to 640 lb/in). Rear MOOG cargo coils (not sure of #). Also went to 16" GNX clone rims and Michelin XGTH4 Pilots from "T" wheels with crummy Radial T/A's. Body bushings all original but missing bushings were added using stiff lowers. All braces added. 1LE lower bushings in rear, uppers original. Shocks changed from stock Delcos to Bilsteins.


A.) Ride smoothness: 1=tooth-jarring, bare rims ride; 10 = 1973 Cadillac "I don't feel the road" boatiness.

Before 8 After 5 - Delco shocks were newish but did nothing


B.) Steering stability over abrupt, jarring bumps: 1 = no effect; 10 = spontaneous lane changes.

Before 5 After 3 - Was never bad, used to float all over but tracked well.


C.) Handling predictability when pushed near extremes of traction in a turn: 1 = it tracks like it's on rails; 10 = what zip code are we supposed to be in?

This should be 2 questions. I have seen highly capable yet unpredictable cars.

C1 Predictability 1 Does exactly what I expect, 10 Random responses.

Before 6 After 3

C2 Capability 1 Corners on rails, 10 Only goes straight

Before 7 After 3


D.) Rear-axle wheel hop in a straight line, if car can break traction in the rear: 1 = no hop; 10 = boing, boing, boing...

Before 1 After 1 - I have a peg leg


E.) Overall sense of "connectiveness" between driver and road: 1 = Vulcan mind meld; 10 = 1973 Cadillac "Road? What road?"

Before 8 After 2

 

[Racer X]

It has been a looong time since I did my upgrades so I don't really remember the differences.

The rubber bushings will give a softer ride and they also help to insulate the car from road noise. Not as predictable at extremes.

Poly's can be good ONLY if they are greasable. Otherwise they squeek, but they are a good comprimise as you state.

Solid bushings give the best predictability but they will be harsh and you will get a lot of road noise.

 

[MAP]

Thanks BJM and Racer,

BJM > thanks for your numbers. About handling "predictability" versus "capability," I was really solely after the predictability part; I'm not trying to ascertain maximum centripetal acceleration. Thanks for drawing attention to the apparent ambiguity in that metric; hopefully this clears it up.

Racer> I mostly agree with your theory.

Best,
MAP

 

[Racer X]

Originally posted by MAP
...Racer> I mostly agree with your theory....

Thanks, but it's not my theory. I haven't had an original thought in years.

 

[MAP]

Hi Racer,

LOL!

Folks, for your curiosity, here's a direct link to the montecarloss bulletin board, where the survey has more history and responses: http://www.montecarloss.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=18;t=001565

I'm looking forward to many more responses here - thanks.

Best,
MAP

 

[Matt Weiser]

I can't answer the "before" part because I tore my wagon apart soon after buying it to do the drivetrain swap and suspension upgrades. My goal was to build a firm road-trip car also good for auto-xing and track days, so I wanted to make it ride on rails without beating me up.

So I have Global West front upper and rear lower control arms, Del-a-Lum bushings in front control arms, new rubber bushings in the rear uppers, Bilstein shocks and Moog 5658 springs in front. I haven't touched the stock frame bushings or the rear springs. I figured the stock rubber frame bushings would insulate the driver/passengers from the harshness of the Del-a-Lums, and that seems to be the case. However, I get a lot more road noise in the rear, probably due to the spherical bearings in the Global West rear control arms. And also the wagon body probably amplifies this effect somewhat (vs. the coupe). Wheels/tires are 16x8 GTA rims with 245/50 Yoko AVS dB tires.

The DAL bushings give absolutely fluid motion, great road feel without a lot of harshness, and they eliminate any bushing-related feel of looseness or wobble.

IMO, a problem with our cars that's hard and maybe impossible to fix is the general steering "numbness." There's very little road feel through the steering wheel on our cars. I'm wondering if the rack & pinion conversions now available would fix this...?

My ratings:

A.) Ride smoothness: 4

B.) Steering stability over abrupt, jarring bumps: 1

C.) Handling predictability when pushed near extremes of traction in a turn: 2

D.) Rear-axle wheel hop in a straight line, if car can break traction in the rear: Can't say, my posi is nearly blown so I've been babying it.

E.) Overall sense of "connectiveness" between driver and road: 3

 

[MAP]

Hi Matt,

Thanks for your response! Just to clarify a little - Global West makes three different kinds of control arms for the G-body lower rears. Which one do you have?

About the steering response, I suspect that R&P is ultimately the way to go, but I have a Saginaw 800 box built by Guldstrandt Engineering, with their high-effort 35PSI valve, that communicates far better road feel than the stock 800/650 boxes.

Best,
MAP

 

[Matt Weiser]

I have the Global West #TBC-8 rear lower control arms, with spherical bearing in the front bushing location and Del-a-Lum in the rear.

I didn't know about that Guldstrand steering box. Sounds like a nice unit. Is that a bolt-on and how painful is the price?

 

[MAP]

Hi Matt,

The Guldstrandt box was purchased back in mid-'97, as I recall, and cost somewhere between $300-$400 (I don't have the receipt, unfortunately.) At that price, I hesitated before buying it, truth be told, but I've been happy with the results. If you already have an 800 box, the unit is a direct swap. If you're starting with a 650 box, you'll have to swap the Pitman arm for the one used with the 800 unit.

Thanks for clarifying about the Global West arms. I have to share one reservation that I have with these units, that I described to the technician when I called GW: by using a cylindrical Del-A-Lum bushing in the rear of the LCA, the arm is constrained against rotation about a vertical axis. Since the roll center of the rear is about 18" high (near the top of the differential case,) and since the LCA's are located some 11" or so below this point, any rear roll must be accompanied by sideways deflection of the LCA's at their rear attachment points. This requires rotation about a vertical axis. Since the Del-A-Lum's constrain against this motion, they tend to put the suspension into bind. This may impart unusually high stresses to the suspension/chassis in either a condition of high roll in a turn, or when one or the other rear wheel traverses a significant road irregularity. Since the LCA's, rear, and chassis are less than infinitely rigid, one would at least expect the same result as adding a very thick rear sway bar: rear roll stiffness should climb significantly.

I take it you've experienced no adverse effects?

Best,
MAP

 

[Matt Weiser]

MAP,

No ill effects yet, but to be honest I haven't really pushed the car beyond about 90% so far, as I'm still sorting out bugs from the swap (it's not my daily driver, and the wife has me chained to a long list of honey-dos!). But I see your point and I'll be on the watch for this issue.

 

[Racer X]

Hey MAP,

I see what you are saying about having the four link articulating, now, who sells the LCAs with spherical bearings at both ends? I have checked around and all I could find were spherical bearings at the top/body mount.


Racer(wishing his bearings would articulate)X

 

[MAP]

Hi Folks,

I believe Matt Adams VSE installs spherical bushings (at both ends) into these LCA's. I found two telephone numbers (one or both may be out-of-date,) and no listing for a web site. The numbers are: 1-831-659-7660 and 1-408-649-8423.

HTH,
MAP

PS: Any more people out there willing to participate in the survey? May I suggest that people with 12-pt or higher roll cages, and who actually drive their cars on the street (if even once in a while,) may have meaningful data to add? Thanks.

 

[wileecoyote]

reply

MAP, I've read many of your posts and noticed you seem to know quite a bit about the theory and principles of suspension movement and allowable tension. In all your research and discussions on the boards, what is your conclusion for the best setups?? It would be great if you could give us a budget setup, a midrange setup, and an all out/change it all, Watts/ all out setup. Also there are those of us who are 1/4 milers and road runners(pardon the pun!) so one for each side would be a great definitive!

 

[wileecoyote]

ttt

ttt

 

[Gary Wells]

Started suspension work/parts replacement on my '87 turbo-t at about 17K miles, it now has about 19K miles on:
Bilsteins all the way around.
Installed #'s 3 & 4 lower body bushings & GNX upper body bushings with Kirban's factory replacement (rubber) body bushing kit.
Kirban's lower front frame brace & the lower 2 trianglular ones that hook to it.
Kirban's front & rear stock height replacement stiffer spring set.
Upper rear BMR tubular control arms, spherical bearings front(body) side, & left factory rubber bushings in place at the rear.
Lower rear Global West tubular control arms, spherical bearings front side & Del-A-Lum bushings at the rear.
FTS&S 1 3/8" rear sway bar (solid), but I would have liked to try a 1 1/4" solid rear sway bar if one was available. Neither 1 1/8" nor 1 1/4" rear solid sway bars are available for these cars.
16" GTA (GNX replica) rims and Michelin Sport Pilot on all 4 corners.
----------------------------
My only regret so far is that I did not sit down the minute that I bought the car 3 years ago (8K miles) and buy and have installed the stuff.
---------------------------
The Global West Del-A-lum bushings are only a part of the suspension package and dependent upon what is installed at the other 3 corners of the suspension
Next: Savitske (SC&C) Street Comp II fully adjustable front upper control arms & tall upper & Lower ball package. Awaiting receipt soon hopefully
--------------------------
My suspension set-up does not show any bind at any of the 4 control arm hook up points. I was told by Global West, BMR suspension, & my installer that the suspension would not bind unless I went to a solid mount at the 4th, or upper location, and that is why everybody recommended using the factory rubber at that location.

 

[Jon B.]

Hi Matt,

The Guldstrandt box was purchased back in mid-'97, as I recall, and cost somewhere between $300-$400 (I don't have the receipt, unfortunately.) At that price, I hesitated before buying it, truth be told, but I've been happy with the results. If you already have an 800 box, the unit is a direct swap. If you're starting with a 650 box, you'll have to swap the Pitman arm for the one used with the 800 unit.

Thanks for clarifying about the Global West arms. I have to share one reservation that I have with these units, that I described to the technician when I called GW: by using a cylindrical Del-A-Lum bushing in the rear of the LCA, the arm is constrained against rotation about a vertical axis. Since the roll center of the rear is about 18" high (near the top of the differential case,) and since the LCA's are located some 11" or so below this point, any rear roll must be accompanied by sideways deflection of the LCA's at their rear attachment points. This requires rotation about a vertical axis. Since the Del-A-Lum's constrain against this motion, they tend to put the suspension into bind. This may impart unusually high stresses to the suspension/chassis in either a condition of high roll in a turn, or when one or the other rear wheel traverses a significant road irregularity. Since the LCA's, rear, and chassis are less than infinitely rigid, one would at least expect the same result as adding a very thick rear sway bar: rear roll stiffness should climb significantly.

I take it you've experienced no adverse effects?

Best,
MAP

While I agree with the binding that is inherent to poly or any other bushing, the "compromise" that most people want and/or need is to have said bushing and a rod-end type on the other side. 99% of the drivers on the road do not need a rod/rod type combo for their cars.

Now, I dont know how this applies to cars like the G-body, since it has the body bushings to factor in. But with a car with a unibody, like my Trans Am, the above holds true. I'm also not taking into account the four-link type setup binds inherently.

My $0.2,
Jon

 

[BJM]

Most people treat rubber bushings like a poor cousin. The big assumption is that whatever compromise you have to make with poly (binding, harshness, excessive roll stiffness, squeaking) is worth it because rubber is mushy and won't give you good handling. The truth is everyone is replacing worn out rubber with new parts. Moog's normal rubber bushings sold today are as stiff as the high durometer stuff sold when these cars were young (1LE rear LCA bushings are the exact same as the normal Moog rubber). Several years ago I fully rebuilt my Buick's front suspension and replaced all the rear LCA bushings. I refuse to use poly except maybe on the sway bar links. In all cases I used Moog replacement rubber. My Buick had slot car handling after all that work. How many people who upgraded to poly first tried all new rubber? Nobody wants to do 2 complete rebuilds so they never know how good new rubber actually is.