I am basing it off the up and down movement of the suspension, where I notice the ride tends to be stiff on soft bumps and rather harsh on more severe bumps. Unless the bilsteins I was shipped was not designed for stock height, the dampening seems a bit much. I seriously doubt, from my memory, that rubber bushings would tame what I am feeling. I could be wrong, maybe what I was feeling is indeed the front and rear control arms binding up badly despite no squeaking or anything to support the hypothesis. If the polyurethane bushings are not squeaking then arguably they may not be binding either. So, I have to assume my shocks may be the problem, the dampening seems too stiff. This is just my take on it.

If no shop in the past was willing to diagnose my suspension when I expressed these concerns then how was I to know?


Then I am best to shoot BMR an e-mail regarding this matter. There has to be a way to get O.E. bushings to fit in BMR control arms, or any aftermarket for that matter. All I can do is ask at this point, ask BMR and if it comes down to it, asking the mechanic.


Is it a matter of patent rights? It seems like everyone selling bushings needs to make them different somehow. I fail to see how sap-like liquid rubber can bond to the metal casing used in the control arms as a bushing yet liquefied polyurethane can't do the same thing when allowed to cool and solidify in the exact same way. They do make softer polyurethane that is equal in hardness to rubber used as bushing material. How the bushings are made now "stiction" is going to result; if they were made the same as O.E. rubber bushings I seriously doubt they would behave differently and in all honesty not require greasing like their high-performance counterparts that stick and bind.

For now, I have to wait and find out what happens on Tuesday and what the mechanic manages to find. It is better I learn about this now rather than having waited to do this later on with a brand new custom car.

 

I should be able to use rubber bushings in my aftermarket BMR control arms. I have sent both BMR and Summit Racing inquiries about this, so I will get the final verdict and whether I can use the O.E. bushings for my car in the BMRs.

So, pretty much I need rubber bushings in my upper and lower front control arms and the rear control arms. What about my BMR panhard rod? Is there any problems in having polyurethane bushings for that?

As far as my car's anti-sway, had I known back in 2013, perhaps swapping bushings over to polyurethane would have given me a bit of what I was looking for. For my current set-up, I need that 21mm rear sway bar and will get aftermarket polyurethane bushings for it. I can salvage my polyurethane end links from the BMR sway bar.

 

That could very well be due to the bushings (binding) and that bigger rear swaybar. Ive never heard anyone say bilstiens dampening is too much, if anything people say its on the soft side of he spectrum.

All factory bilstiens (not custom) were made for the stock springs.

They definitely do NOT need to squeak when they bind.

Searching here would have helped. You gotta remember 95%+ of the shops out there are not used to/don't want to work with aftermarket stuff, and sure as hell won't diagnose anything based off aftermarket suspension.

At one point in time I think they made some rubber bushings for their rear LCAs, but doubt their front. I don't see why you are pushing so hard back against just replacing the things and doing it right this time around. Take em off, sell them and chalk it up as a learning experience, move forward with parts that are better suited for what you want to do instead of bandaid fixing things.

IDK, like it said I would assume if it were possible and it was that simple (and cheap) it would have already been done by now.

 

That is my fear. I have been looking up binding cases where squeaking was not prevalent and yes, it does happen.

Another thing that dawned on me which you mentioned way back, there is a high probability that the grease I was using was also trapping moisture at the bolt holes and with time it rusted the metal and weakened them. This is another reason why the rubber bushings are looking more attractive now, although I wish I could buy polyurethane equivalents set up no different and just as soft as the rubber.

I bought mine from Summit Racing. You are probably right, my polyurethane bushings in the control arms are probably binding badly.





The only reason I first signed up to this forum was to inquire about problems I had noticed with my car. At the time I was spending this kind of money to switch my suspension to total aftermarket I was also buying into the marketing of K&N air filters. The sad thing is, I have to learn the "hard way" and be proven wrong then swallow my pride and admit I was wrong. This suspension problem of mine is unique, only the control arms with their polyurethane bushings seem to be the clear problem and everything else, aside from the 25mm rear sway bar, was a decent investment for handling upgrades. I just need to figure out if you can swap O.E. rubber bushings into aftermarket BMR control arms both front and rear on my car. As per Summit Racing, I should be able to, I just need a definite verification by both Summit and BMR and whether those replacements are the original factory bushings for the factory stamped control arms.


I am going to see if I can salvage this mistake of mine. I refuse to throw those stamped factory control arms back on my car if there are ways, even if cutting is needed, to fit factory O.E. rubber bushings onto BMR control arms.


Well, then perhaps doing it at home and using spent rubber control arm bushing cases will have to be something I consider down the road... The way I see it, perhaps making soft rubber-like polyurethane control arm bushings is not going to result in more purchases of the product. Polyurethane is supposed to have better wear and tear than rubber and it doesn't oxidize, is not affected by road salt, and any oil contamination won't lead to it's expedited degradation. These days, it is not profitable to make products that last for decades like they used to. For now, rubber bushings will have to do, I simply don't have a choice. So long as the rest of my suspension is not in need of bushing swaps to rubber.

 

No. For the front, you only need rubber for the caster bushing. It's the rear bushing in the front lower arm. You can leave the poly in every other location in the front arms. I am running delrin in my front uppers and they are even harder than poly. I still run a stock bushing in that rear location of the stock lower arm it works fine. Even if you gave me the choice to run a BMR part there I would choose stock 10/10 times.

For the rear, you either need stock rubber in the LCAs or rod ends or roto-joints. You could buy an used set of stock arms and have a shop press new Moog bushings into them. Stock arms are lighter than all the steel aftermarket ones and it's not a location that needs much strength.

Even though you see no signs of your parts binding, I promise you they are.

 

landstuhltaylor & JD are spot on about poly. The caster bushing, and lca's accommodate much more than rotational movement around the bolt. Those bushings locations need to compress to support proper movement. In fact the caster bushing doesn't rotate around the bolt at all, it's entirely dependent on the bushing material's ability to compress. Something poly is designed to resist.

You can get lower durometer poly, but what's the point? There's no juice in that squeeze at all. Lower durometer poly will cold flow and wear out faster than rubber, and you lose the alleged benefit (low deflection). If you want low deflection go with arms that use rod ends or johnny joint style bearings.

Different application, but same idea below in this video. As with the caster, and lca bushings on an f-body, the C4 trailing and camber rods arms are multi axis joints. Poly is a bad choice any time you have a joint that needs to support movement in more than a rotational axis . Grease won't make a poly joint compress, it only helps in rotation

 

Understood about the caster bushing for the lower front control arm. My concern though is that the upper fronts are also binding, so I might as well have those bushings replaced with rubber as well.

For the rear control arms, there are many things that could have caused the bolt hole to expand, and I can no longer ignore polyurethane bushing binding as one reason, and the greasing possibly trapping moisture at the very edges of the bolt holes on the brackets which rusted them over time and permitted the widening of the hole. I chose these aftermarket suspension parts for my car to help reinforce it along with improving the handling for those times when I want to zip around expressway on/off ramps at speeds deemed unsafe for standard vehicles. Later on I will likely autocross given my joy for tight turning.

Anyways, I am not concerned about weight, the rear of my car needs more weight anyways although the difference here is minuscule at best and for what I need for winter traction purposes. The real practical aspect of having these tubular control arms is pot holes. They can take more abuse than factory parts, and again, the bracket holes probably pulled out over time during pot hole strikes. The question I have is, can you swap O.E. rubber bushings in to aftermarket control arms, be it BMR or UMI or what have you. I should be able to but I am waiting on confirmation and whether those bushings are the same for factory control arms.



You brought up a good point about cold flow, although I have been reading that polyurethane has a high resistance to temperate extremes in general. For example: http://www.precisionurethane.com/urethane-advantage.html
Also, you probably could alter the chemistry a bit to make polyurethane more resilient to the effects of the cold if it somehow lacks this in some form with lower durometer rating. With rubber we have had around a century or so of all of the research and development that can be done with regards to automotive application. Polyurethane still demands more R&D before we poo poo it as unable to compete with rubber as a bushing material or even for use in basic road car tires.

I understand grease only helps in one movement of polyurethane bushings. Now that I realize what the problem is with my current suspension set-up, I aim to fix it and hopefully my shocks are still good that I can experience them the way they are supposed to be in my car. [ Post edit: Thank you all! ]

One last thing, are polyurethane bushings in the panhard rod, good? I read that the extra stiffness is welcome, is that true?

 

The front upper arms don't have significant multi-axis motion so if it already has poly in it just isn't worth the effort or money to change it. While rubber will help with impact harshness, it's not going to be significant. Assuming the suspension is allowed to move the way it needs to your primary control of ride quality will be from the damper. Even with rod ends most of the degradation will be from high frequency noise transmitted to the cabin. Because they have no give it also won't allow the wheel to move rearwards when hitting a bump but that is a much more subtle difference.

I have poly/delrin in everywhere in the front including the steering rack with just the OEM rubber caster bushing, then rod ends on everything in the rear. The only single part I would change if it was a real street car would be to use rubber or roto-joint rear LCAs. The rod ends in that location aren't harsh, they just transfer a lot of gear whine into the cabin.

FWIW, this is EXACTLY what I did for 3 years of my life at an OEM. Half of that time testing purely NVH, the other half in suspension kinematics and compliances and how that affects NVH. In other words making cars soul-sucking.

 

Okay and thank you! I am glad you already did the research so I should be assured. This is welcome news, budget wise and it seems performance wise in my perspective, if only the lower front control arm bushing at the caster needs the replacing. The steering may need work too if the rear control arms are not the entire problem I am feeling.

Well, I dropped my car off at the shop. The mechanic seemed to be giving the cold shoulder and didn't sound happy that I was dropping the car off. I know my car is in a sad state, especially when you pop the hood to discover my make-shift modifications for the LS1 air box, but she won't stay like this forever. Regardless, I am eager to get the phone call on the fix and for whatever else they happen to discover.

Post Edit: I got an e-mail from BMR's GM suspension specialist and they do offer rubber bushings for the rear control arms, nothing else. There has to be a way to fit my BMR lower control arm with a rubber caster bushing.

 

if it were me, i would pull those front lower control arms off and sell them. then you have two options IMO; use that money to find a set of used set factory lower control arms and just put new moog rubber bushings in them (for peace of mind) and install or use that money to go towards a new set of BMR lower control arms that have a front poly bushing and rear rotojoint/rod-end castor bushing to keep it from binding. i happen to have the latter installed on my car because i like the adjustability of the aftermarket arms, but obviously that is going to be more expensive. you should easily be able to break even selling your current arms and going back to factory or even make money. my .02

 

I would prefer to not put the factory front lower A-arms back on my car if I don't have to. I am very happy with my BMRs although I wish I had found out about the caster bushing issue when I had these put on years ago. Pretty much it is a dead end from BMR. They suggested a spherical rod end. The best summit could suggest was to put on the factory O.E. rubber bushings meant for the factory lower A-arms. You are suggesting the rotojoint/rod-end.

I guess two out of three, I have my answer if I wish to keep my BMR arms.

CAR FIX UPDATE: Apparently the problem was that my rear control arm bolts were so loose that the retaining nuts were ready to fall off and drop the control arms. The shop inspected the brackets and found them structurally sound and no issue with the bolt holes expanding, even the polyurethane bushings were fine. Firestone was so damn sloppy and lazy and carefree that they couldn't replace the washers and tighten the bolts back up. They allowed me to drive my car in this condition. They too have now lost a customer who would have been loyal... It is no wonder I get paranoid that these guys are out to see my car get totaled or put into a position where I am going to get involved in a serious automobile collision due to failed components on my car. They were nice enough to grease the bushings back up before bolting them back on.

The mechanic also mentioned that the welded subframe connectors were not well done and recommended I upgrade to bolt-ons in the future, which I will! For now, though the car is rather stiff up front, it is so much more improved now and solid feeling. He recommended I get an alignment which I feel the car is in need of and maybe I can fit in having those rotojoints installed, depending upon how much the projected service, in-full ,will cost.

I am just relieved that I have my car back, but the next service may be a punch in my gut with the cost.

 

You keep talking down on the "stamped steel" factory parts like they were bad or weak in some way, don't let the marketing hype fool you again, most of stock parts were actually more than strong enough and the real advantage to the aftermarket stuff is the weight saving and in some cases giving more adjust ability. Going back to the stock parts is not a downgrade for a street car, there have been plenty of times aftermarket parts(control arms, torque arm, Kmember - you can search for this there will be a handful of threads about it) have cracked/failed on the street when the stock parts have not.


Im telling you, if you have a garage buy a set of race ramps and some simple tools and start working on your car yourself, its going to save you a ton of money and headaches. The chances of a generic (non speed shop) getting aftermarket parts setup correctly on your car is slim to none.

If you are going to go through the trouble of cutting out the welded in SFC's then do yourself a favor and drive the car with them off for a while and I'd bet you'd be hard pressed to tell the difference without them.
When you get an alignment DO NOT GET A "STOCK" ALIGNMENT - or just have the shop get it in the "green"(good enough). TELL THEM the specs you want.
Go with the following or close to it:
NEGATIVE 1 degree Camber (-1) [stock is 0 to positive camber, that is bad for tire wear and handling]
As much caster as possible (+4 to +5) [this improves steering feel]
ZERO Toe. [lessens tire wear]
*The camber and caster settings might come up "red" on the alignment machine - this is fine - the alignment machine just wants it to be as close to stock settings as possible, which you do not want. Get a print out of the alignment and make sure it matches this or is at least close to it.

 

absolutely nothing wrong with the factory front suspension components for a street car. as JD said, stock can in some cases be stronger than the aftermarket tubular stuff, namely the kmember. like i said, if i were in your position I'd pull the BMR lower control arms, sell those and use that money to get a set of stock lower control arms, press in some fresh bushings and be done. you will probably make some money back doing so.

 

This thread is going to have to come to a close at some point. With this said, whatever the shop did to my car it feels so much better now than it did before. There is no way that tightening my rear lower control arm bolts somehow made my ride quality more tolerable, I just can't believe it. They had to have done something more. I hit some decent rough patches and the ride quality is now more tolerable, I am happy as can be yet in disbelief at the same time. With regards to an alignment, I think I will go through them and even have my inspection at their shop since they clearly know what they are doing.

Right now I am going to keep my suspension the way it is albeit wait for the late spring and after college to install that 21mm rear sway bar myself. I can't do it now and with frigid temperatures and expected snow storms. If my lower A-arms are binding, it is not something I am going to mess with nor concern myself with given the new ride characteristics of the car.

With regards to box frame lower A-arms, if I really were concerned with binding, I would go with UMI heavy duty boxed lower a-arms with roto-joints. From there, I might even consider the delrin bushings for the upper A-arms. For my rear lower control arms, those would have to be UMI with roto-joint/poly combination. However, as I mentioned before, I really shouldn't be complaining about my suspension now that the shop did their fix and I suspect some tweaking to it. It is way better now!

@JD_AMG I have ramps I just don't have a garage to pull the car into and work on it, while also being angled on the ramps. I have to work outside, exposed to the elements, on the driveway.

@hokeplaya05 I won't be going back to the stock lower A-arms especially when UMI sells a superior replacement, their heavy duty boxed a-arm with roto-joints. For now, I am happy with my BMRs and for winter driving, the extra stiffness of my car comes in handy for managing sliding. It dawned on me how excessive body roll in a slide can make it worse which is why there is something to be said about stiff suspension for winter driving.

Everyone, thank you for this discussion! I have learned a great deal from you all and it will be something for me to consider in the future if I decide to go overkill with rotojoints, polyurethane, and delrin bushings using some of my BMR components with newer UMI components. A custom shop will have to remove the welded sub-frame connectors that came with the car when I bought it and put on bolt-on subframe connectors. FantomWorks is not that far away to have my car shipped there for Dan's crew to work their magic. Who knows at this point but it would be cool to see my car on the show. Thanks again guys!

 

[UPDATE:]
I ended up blowing out my rear shocks and my fronts were leaking per the shop that worked on my rear lower control arms. They have since been replaced with Monroe OE Spectrums both front and rear, with new rear springs. The ride quality is just the way it should be from the little I remember when I originally bought the car to how my 6-cylinder base Firebird felt.

The car is not as firm as before but I certainly enjoy the trade-off for more comfort. Running over bumps is less jarring as it was before. I can still corner hard though I need to accommodate for when the car does bounce but that only improves my driving skills with this regained dynamic. I am actually happy with the shocks and I am glad my rear tires now have more traction for hard starts from a green light.