Rear control arm bushings

[BuickMike]

I pulled all of my rear control arms out to box them and am having a hard time deciding which bushings to get. I've got some questions and am looking for answers from those with experience with different styles of bushings.

I don't really want to go all Poly in the rear because of possible binding issues. I drive this thing on the street quite a bit more than on the track. I don't want to autocross, just handle good with some GNX style rims on the street without knocking my teeth out.. I also don't plan on making a wheels up launcher out of it. mid 11's is my goal for quite some time.

I was going to put Polygraphite just in the lower end of the rears and rubber in the rest, but....

If I user rubber bushings, which ones are best, factory?

How are the HR Parts N Stuff Poly bushings?
--They claim to have a different sleeve design to get rid of
binding.

What about Global West Del-a-lum bushings?
--I have heard that they work great, but what about harshness of
ride and road noise?

Thanks in advance for any input.

Mike

 

[GNVAIR]

You wont find Del Alum's for the rear unless you buy Global West's lower control arms. And even still they only have them in one end.
Your best compromise would be Energy suspension in the axle housing (Jeg's sells these as a pair for like $25 and they are super easy to install only requiring you to remove the rubber your originals). Use GM 1LE's on the control arm. Lowers you can use pretty much anything. I have 1LE's in my lowers.
Also note there is no need to box the uppers as they are not under the same stress the lowers are.

 

[BuickMike]

Thanks,

What are the 1LE's out of?

 

[BuickMike]

Nevermind, 1LE is Camaro. I got the part # for the lowers from GNTType.org. They don't have the part # for the uppers. Is it the same part #?

 

[turbofish38]

Originally posted by BuickMike
Nevermind, 1LE is Camaro. I got the part # for the lowers from GNTType.org. They don't have the part # for the uppers. Is it the same part #?

The 3rd gen F-body doesn't use upper control arms. The bushings are different between upper and lower. For the uppers use the poly's. You wont notice to much of a difference in the ride. I think the stock replacements in the MOOG catalog are about the firmest you can get with a stock style rubber bushing.

 

[BuickMike]

Anyone use HR Parts N Stuff poly bushings and have any feedback?

Since they're geasable, would this prevent binding?

 

[urhstry]

I have H&R's Bushings and control arms on my car and I have no binding and I swear it was one of the best improvements I have done to my car. And they are greasable.

 

[Louie L.]

In my opinion the binding issue is non existent. I really would like to to know where that came from. Sure if you install poly bushings on all 4s and over tighten the bolts with the car jacked up in the air is going to bind, but so is rubber.

I have done 2 cars with Polys on stock control arms, to include my own before going to full drag race suspension.I have also installed several Metco uppers and lowers. I never ever had any binding issues. Metco control arms and HR parts all come with Polys , none of them say anything about binding....

 

[BuickMike]

Alright, well I called HR today and ordered my bushings. Way less confusing that deciding what combo of rubber / poly to go with, which duroeter, etc. I'm pretty confident I won't have any binding problems since I can keep 'em greased up.

 

[PEACHS]

HRs are the way to go, have them in all 3 TRs

 

[HRpartsNstuff]

You will be VERY happy with them, on street & racing

We also make a special tool to remove & install the ones in the upper rearend housing. Part # 0599 for $85 in case you run into trouble there. Makes it a 5 min job

PS- Also, it's a good time to box them in too. Our kits make it easy, but adding just about anything to them will help.

 

[Ormand]

I really would like to to know where that came from

The binding can occur because the rear suspension design uses lower control arms that MUST twist in order for the axle to lift on one side. The LCA pivots are simple hinges, not ball joints, so that the axle can't twist without either the bushing deforming, or the LCA twisting. If you box the LCAs, you reduce the ability to twist. If you go with solid bushings, you further reduce the ability to twist. The axle can still go up and down, but both sides have to go up/down together, the axle can't tilt relative to the car, to allow for lean in a turn, for example. It's pretty much basic geometry. You can stiffen the LCAs, and get a good, straight launch on the strip, but it may ride rough, and corner poorly- with sudden oversteer.

 

[DeltaT]

I ran the PolyGraphite bushings in boxed, stock control arms for over 50K miles with no problems and no squeaks. They really helped firm up the rear end feel. Less squirm. I recommend the HRPartsNstuff for the upper rearend bushings. Get the tool as well. Excellent quality, and it is really easy to use on a pain-in-the-butt job.

I did not have any of the problems mentioned in the above post. The suspension felt great. I do not believe the LCA 'twist' theory. The arms are angled so that wheel elevation or depression on one side of the car happens and the axle is allowed to rotate in one vertical plane.

The 4-link has a separate purpose for both the UCAs and the LCAs. The LCAs keep the axle from moving forward or backward in relation to the chassis, while allowing it to move up and down and pivot. The UCAs keep the rearend from moving side to side in relation to the chassis, again while allowing it to move up and down and pivot.

Jim

 

[MAP]

Hi Folks,

Ormand's caution about the tendency toward rear-suspension bind is spot-on correct. One point that had me stumped for literally a few years here at this BB and others, was how the word "binding" was (and still is) applied. I always understood it to mean a condition of interference of some kind that would prevent any motion of the suspension; i.e., that "binding" was the equivalent of "seizing," and was therefore a yes or no, go or no-go kind of condition.

I've since learned that "binding" is commonly used by posters to mean a tendency toward ultimate seizure, and not seizure itself.

That out of the way, Ormand's points are all correct. The bushings and arms twist and deform in a complicated way because of the inherent nature of a converging 4-link rear, with a very high roll center (roughly 18") from the factory. All four CA's have stresses imparted to them as the suspension works over bumps, that induce a twisting deformation. Box the arms, and the bushings will exhibit higher strain rates. Or use stiffer bushings, and the arms will twist more. Since bushings have non-linear compliances, a higher strain rate in the bushing is generallly undesirable because it tends to make the rear handle in a "twitchy" way that decreases driver control. PU bushings are especially undesirable in this regard because of their long-term creep characteristics which tend to worsen their non-linear compliance under rotation about any axis perpendicular to the bushing's axis of symmetry.

The worst scenario is a combination of the two, namely, boxing the arms and using PU bushings. If the car is driven hard over bumpy surfaces, such a combination will do anything but instill confidence on the part of the driver because the rear simply reacts unpredictably, and the effect worsens with the passage of time, as I've learned over 15 years with various G-body cars.

Linear systems rule!

Best,
MAP

 

[BJM]

The upper arms definitely twist

That's how they work. If anyone disbelieves this its because they haven't really looked carefully at the suspension. That's why the bolts only slip in with the axle in one specific position. Lift and lower the axle and you can see the misalignment occuring. Once the bolt is in place the arm/bushing twists instead. The stock upper arms allow the twist to occur along the whole length of the arm. Boxing them forces all the twist to occur in just the end of of the arms and mostly in the bushing itself. The use of a stiffer bushing puts large loads into the cross member as well as making the ride harsh.

A lot of people equate a harsh ride with good handling. Its just not true.

 

[GNVAIR]

Originally posted by turbofish38
The bushings are different between upper and lower.

That is incorrect. The G bodies use the same bushings in all 8 positions on the rear axle. The f bodies share a lower control arm with the G bodies and as such, the stiffer 1LE bushings can be used in the upper AND lower control arms of a G body. As of 2-3 years ago, GM was still selling the 1LE F body bushings individually. I bought a complete set and that is what I currently have on my car.

 

[GNVAIR]

Maybe the proper terminology would be "bushing induced travel limitations". The "bind" as people were refering to is not noticable to a drag car as the rear suspension has no where near the articulation that a road car would encounter.

 

[BuickMike]

HR bushings installed!

Well I boxed my UCA's and LCA's last week and installed my HR Parts grasable poly bushings. So far I am very happy. I can now feel my tires grab when I hit corners opposed to before when I could actually feel the rear arms flexing which would make the rear end feel like it was swaying horizontally. There is a little more road noise on large bumps, but it is almost unnoticable. The rear end is not skating around on bumpy roads or corners. I even got into some boost around a few corners with the intention to get the car sideways. I have to say it was very predictable and came back nice and straight unlike before when the rear would slop around a little during a recovery.

I'm very pleased with my HR bushings!!!

 

[HRpartsNstuff]

THANKS!

We found that the "binding" associated with standard "poly" bushings comes mostly from the center steel sleeve being WAY too tight in the poly & not being greased. What happens is that you go into a corner, the poly flexes & things take a "set". When coming out of the corner, if the center steel sleeve can't move easily in the poly, then it restricts movement & binds up. Then once it has enough pressure, it jumps & moves all at once, causing understeer/oversteer and unstable conditions. On small turns/movements, there is so much resistance/bind on a standard poly bushing that it doesn't even let the suspension move to follow the road & steer where you want it to. Mass produced & cheaper upgrades are usually not the best way to go.

Making our new arms with new poly design, we cured all that. Our replacement bushings have that same design & benefits. We HIGHLY recommend boxing the arms at the same time, since the added stiffness of poly over stk rubber may just flex the stock arms more. A little side stiffness in the poly helps the car handle better, AS LONG AS IT MOVES FREELY.

In drag racing, that extra resistance of std poly bushings slows or stops weight transfer, making traction much harder & inconsistent from one run or one track to another. Some cars if you blast it hard enough off the line, it covers this issue up so you don't notice.

Hope that helped!

 

[HRpartsNstuff]

Went to EDIT & add stuff to above post, but it took longer than 10 min, so here it is

We found that the "binding" associated with standard "poly" bushings comes mostly from the center steel sleeve being WAY too tight in the poly & not being greased. What happens is that you go into a corner, the poly flexes & things take a "set". When coming out of the corner, if the center steel sleeve can't move easily in the poly, then it restricts movement & binds up. Then once it has enough pressure, it jumps & moves all at once, causing understeer/oversteer and unstable conditions. On small turns/movements, there is so much resistance/bind on a standard poly bushing that it doesn't even let the suspension move to follow the road & steer where you want it to. Mass produced & cheaper upgrades are usually not the best way to go.

Making our new arms with new poly design, we cured all that. Our replacement bushings have that same design & benefits as our new arms. We HIGHLY recommend boxing the arms at the same time, since the added stiffness of poly over stk rubber may just flex the stock arms more. A little side stiffness in the poly helps the car handle better, AS LONG AS IT MOVES FREELY. You also have to start looking at the next weak link, the frame brackets for the LCA's. That's why we made a HD brace kit #0251 that ties the frame bracket on the forward end of the lowers into the frame MUCH better. Added stiffness = more stress transferred quicker thru the frame & brackets. That's why you usually see a lower 60ft time with rear susp upgrades.

In drag racing, that extra resistance of std poly bushings slows or stops weight transfer, making traction much harder & inconsistent from one run or one track to another. Some cars if you blast it hard enough off the line, it covers this issue up so you don't notice. Our setup lets the arms move fast like a rod-end would, but have way more side stiffness (over rod-ends) to help handling & help keep it straight & level off the line. Best of both worlds! Only down side is, at about 1.40 60 ft times & faster, our HD poly is starting to loose the ability to take the stress without flexing too far. We make a super HD Delrin upgrade which cures that, but it's more of a race only setup. There are a few in the super fast street class (high 9's & quicker) that we are looking into a special setup for. Really, our poly covers 97% of applications, and Delrin for the top 3%.

Hope that helped!