alxltd1

I am replacing the control arms on my 2000 coupe and after researching have decided to go with rubber bushings instead of poly or delrin or solid to preserve the ride for a daily driver. However, learning that you cannot buy the rubber bushings separately as they are bonded to the control arms, I am replacing the arms. One alternative is the T1 arms from GM (now Chevrolet) Performance. I found the following part numbers (front only as it seems the T1 arms with heavy duty bushings are only available for the front):
T1 Control arm part numbers:
12480072 Arm - T1 Front Upper LH
12480073 Arm - T1 Front Upper RH
12480077 Arm - T1 Front Lower LH
12480078 Arm - T1 Front Lower RH
I can find all the above part numbers on the GM parts sites except for the T1 Front Lower LH (12480077). I have posed email questions to the vendors but have not yet gotten a response. Does anyone know if there is an alternative part number for this particular control arm or is it discontinued?
Thanks.


UPDATE: heard back from two of the GM parts vendors that the T1 Front LH Lower control arm is discontinued. Does not make sense to discontinue one arm and continue to produce the rest but it is what it is. So will either have to use the standard control arms or rethink the Delrin or Poly alternative. Thanks.

Fast one

If you can't find the a-arms: Delrin is hard for the street but poly is almost as good as rubber and should hold up fine, the durometer rating or hardness is what counts so ask the bushing vendor what that is compared to the GM rubber; the sticky marine grease is a must use for either.

Sam Handwich

It may be discontinued, but someone might have one in inventory. I am having a hard time finding a certain piece of rubber molding/weatherstrip, but it seems like i found it, and have a backup as well. Maybe try Corvette Central and/or zip-corvette.
Also, you might consider rebuilt T1 control arms. I would guess they can be rebuilt.
Good luck.

neutron82

I would consider poly bushings over buying brand new control arms... a poly bushing set is around $500, I can only imagine what a complete set of new gm control arms would cost... surely you would be able to sell your current control arms to recoup some of that money but in the end you would probably still be in it for much more than a poly bushing set... in my experience polyurethane bushings are slightly harsher over bumps when compared to rubber but when on a good surface are much tighter/smoother feeling... the only slight drawback is if you drive the car daily and they get wet they might be a little squeaky when they dry out, a shot of silicone spray/wd40 or grease as suggested above will keep them quiet

Gordy M

Check with Froggy on the roadrace autocross forum. he had a set of slightly used ones for sale. $about 500.

alxltd1

In researching the choices it becomes obvious there are pros and cons to all. I have eliminated the solid bearing route as the car is not a dedicated track car and will see street use more than track. Though it may see an occasional auto cross or HPDE event but more frequent spirited driving on twisty roads.
Poly it seems has a reputation of enhancing performance by reducing deflection and improving steering response but at the expense of increased ride stiffness or harshness and a tendency to squeak if not kept lubricated well enough. It looks like there is also a wear factor that over time reduces the original benefits they give to the suspension.
Delrin it looks like is more durable than poly, does not have the noise factor that poly has, but that they increase the stiffness or harshness of the ride even more.
Stiffness or harshness is somewhat a subjective term and most may view it differently. Do I want a luxury car floating suspension absorbing every bump and ripple in the road with a numb steering wheel? NO. Do I want a rock hard ride that while is like being on rails will shake the fillings from my teeth at the slightest imperfection in the road? NO.
Unfortunately unless you can ride in a representative example of each, and that sample also has the other suspension mods similar to your own car, it is a crap shoot. Also, the bushings are one component of the suspension and together with the other components will effect ride and response.
So, my ride is a 2000 coupe with Stance Coil Overs (on the standard rate springs for their offering on the C5), with C6 Z51 sway bars on OEM rubber bushings and all metal end links. The spindles are the LG drop spindles and their spherical bearing in place of traditional ball joints, with OEM hubs, and it sits on C6 GS wheels (18 X 9.5 fronts on 275 X 35 tires and 19 X 12 rears on 325 X 30 tires all with C6 Z06 brake calipers and rotors). All tie rod ends are original and in good shape. The current control arm bushings are the original OEM rubber that came with the car. While not showing any significant visible wear, they are now 16 years old and while I was doing all these other mods I thought to freshen them up with new rubber replacements, or an alternative.
Given that the rubber bushings are not available except as part of complete control arm replacement, and that cost is relatively high (approx. $2400 new from a GM parts supplier), I was leaning towards the Delrin as I would like to not have to worry about constant lubrication and eventual wear issues. I would love to ride in a car with them in, and with similar suspension mods as I have already done, to gauge “stiffness or harshness” but I doubt I will have that opportunity.
The question is: How harsh would you describe the ride as a percentage as compared to stock with either Delrin or Poly bushings? For example is the ride 25% more harsh, or 50% more, etc. Again, I understand that all answers are subjective, just trying to get a feel before deciding to change, if at all, or just buy new control arms with new rubber bushings already installed.
Thanks.


Thanks I will check it out as well.

MySR71

Here's the link:

https://www.corvetteforum.com/forums...ale-c5-c6.html

Fast one

After several years of use or about 30,000 miles, the poly bushings remain squeak free and continue to provide the same ride quality as when they were new; the marine grease was only added once for the initial installation. Pfadt coil overs and Z06 sway bars were installed about the same time that the bushings were changed and the bushings were from Pfadt. I once put Delrin bushings in another the car and could feel every defect in the road, the ride was harsh like a hammer hitting the frame when going over bumps. Think of a sine wave as rubber bushing performance and a sawtooth as Delrin bushing performance, the poly bushings would be closer to the sine wave than the sawtooth.

alxltd1

Thanks. It looks like the poly are more inline with what I would require for how I use the 'vette.

Solofast

Poly bushings can be a PITA

Here is a thread from the Autocross and Roadracing page that talk about the topic in detail.

https://www.corvetteforum.com/forums...s-options.html

The easiest and best solution for a street car is to flip the rear upper bushing on a new set of arms. If you do that they won't walk out and you'll never have an issue with control arm bending. That is the easiest and least expensive fix. You'll be surprised that the stock arms aren't that expensive and if you flip the rear bushing it will never walk out.

OE replacement arms are around $160 each on ebay and you may be able to find them cheaper if you look hard. Replacement arms from Rock Auto are only $79 each

alxltd1

Solofast, thanks for all the information and links (the links were both the same thread, was there another thread you were referencing as well?). I respect your opinion and insight. I have read a ton of threads on multiple sites regarding the Poly, Delrin, and solid bushings, pros and cons. I also saw the info on flipping the rubber bushings. As in all things there are varied and differing experiences and opinions. Those who have had absolutely no issues with whatever choice they made to those who swear it was the worst thing they ever did. Sort of like opinions on getting married.

The research I did on pricing control arms is just as varied. New OEM arms from the main GM parts vendors were expensive. New front uppers ranged from $366 to $445. Ebay from $160 to $199 and aftermarket (Mevotech) from $80 to $95 (I am assuming these from Mevotech are acceptable quality).

I wanted to refresh all the bushings on the car so if I did the rubber bushing flip on the front uppers I would still be looking to replace the front lowers and all the rears. I did not see aftermarket arms available for the front lowers or any of the rears but I may have missed a source. So it still may be a more expensive option to do the rubber flip and then have to also buy OEM arms for all the others. I would also think mixing new rubber and Poly on different arms is not advisable?

I can replace all the bushings in my current arms with Poly for about $400 depending on which ones (VBP, Pfadt/AFE, Energy Suspension) and even if I wanted to purchase used arms for all and just swap them out it would add about another $400 or so for all the used arms. Labor would be my own and adding zerks would be a minimal add on if that would avoid the squeak issue from the Poly.

So back to the original question which was, how harsh would the ride increase with Poly bushings expressed as a percentage increase over stock (again given the other mods already on the car as in the original post) and knowing it is still somewhat a subjective answer?

It may be in the final analysis better to just bite the bullet and replace all the control arms with fresh arms with rubber bushings and do the flip on the front uppers.

Solofast

Rock Auto has aftermarket lower arms as well for a very reasonable price.

Unless your rears are cracked and rotting the rubber doesn't deteriorate that much, most of the problems with these arms are related to the front arms bending and coming off of the rubber bushings due to high forces generated by braking with sticky tires like Hoosiers. I realize that these bushings are getting old and I replaced my upper arms four or 5 years ago because they had deformed and walked off the bushings. But unless you're looking for the very last increment in handling on the track with sticky tires it's a lot easier just to flip the rear bushing, change out the arms and be done with it.