Webineer

Need some advice.
I have a 72 vert with a mildly built 350 and I am about to install a high performance suspension kit from Mid America Motorworks. The kit does not come with control arms and my mechanic is telling me to purchase all new upper and lower control arms with ball joints installed. Besides looking nice, why would I do this and spend all that money vs. replacing the worn rubber with new rubber for a fraction of the price? I appreciate any input and if you guys see it the way my guy does, I'll go with the replacements.
Thanks for your help.
Paul

teamo

Most people upgrade to the tubular control arms vs. stock for a performance type suspension. The stamped steel GM control arms are not as strong and have a certain amount of flex as compared to newer tubular arms that are built to withstand more vigorous driving. It depends on what you plan to do with the car. I'm just restoring my suspension as a cruiser so I will be restoring the original control arms with new ball joints and bushings. If I was going to race it or do competition type driving I would upgrade.

henrikse

I just rebuilt both control arms with bushings, ball joints and they turned out great. I bought mt Bilsteins off a guy who had used tubular on his but was going back to stock. He used them for racing.
I got all moog parts from Rock auto for I think was a great price compared to some of the kits available.

cagotzmann

Waste of money to replace the upper or lower arms unless they are damaged. Street use.

if you plan on autocross and using street tires, this would be better with poly bushing everywhere and still ok with stock arms.

if you are running very sticky tires for track days then it may help to have other arms. I have a complete vb&P street & slalom with poly everywhere running 275 Nitto NT01 track tires and using SPC Upper arms with stock lower arms. Upper arms only to aid in alignment adjustability. I ran with stock upper arms as well. But since switching the NT01 tires the suspension has more stress than before.





Replacement of ***** joints should be checked before the suspension is removed. Easy to check if they are worn. All new ball joints isn't a big expense, and are not that difficult to replace with the arms out of the car.

Also before you purchase the kit from Mid America check the brand of rear spring, you may end up with very high ride height.

Some of the kits are similar to VB&P kits which are known to provide proper ride height.

vb&P kit
https://www.vbandp.com/c3-corvette-p...77-detail.html

mid America kit
http://www.mamotorworks.com/Corvette...ystem-618080-1

both have a non factory rear sway bar mounting system, which may cause some binding of movement of the rear trailing arms.

The only other reason to replace the upper arms is because you cannot get enough front end caster alignment you desire. Even then there are options to re-use the upper arms as well.

OldCarBum

I talked with several performance suspension tubular A arm manufactures and purchased my upper tubular A arms through Van Steel. I plan to use my Corvette as a cruiser, however I live in Northern California where there are awesome coastal, foothill and mountainous twisting roads where can carve up the curves like I did on my Ducati. Dan at Van Steel advised me to replace the upper A arms to gain the built in 6% added caster to better set up the suspension for straight- a-ways and for cornering. Dan added that I Would gain nothing swapping out the lower OEM A arms except for some weight savings. He also strongly advised to install a spreader bar which he said will greatly increase stability and reduce or eliminate much of the twisting of the frame in cornering or even day to day cruising.

Metalhead140

I also have tubular uppers and stock lowers (with poly bushes and moog ball joints), as the aftermarket lowers are all (to the best of my knowledge) the same geometry as stock. The uppers allow more caster and a a better camber curve.

No reason not to to stay with stock arms for a street car, but you'll probably want to do ball joints as well as bushes. If you're paying a mechanic to change them (it's not difficult to do yourself) the complete arms will cost you quite a bit less in labour than swapping bushes and ball joints in your current arms, as that takes a fair bit of time. Whether it would be cheaper overall to have a mechanic swap out a complete replacement arm I couldn't say.

ignatz

One advantage of the adjustable arms is that there are no shims. So if you have a spreader bar you don't have to change its length for each and every new alignment.

jb78L-82

If you are not racing, stock control arms rebuilt with upper and lower new ball joints and poly control arm bushings are terrific. I was shocked when I installed the poly control arm bushings in place of rubber....BTW-they ride great with very little ride degradation, at least the poly I used. Add a front spreader bar with that kit and you will have nice handling C3....

Webineer

All fantastic advice, thank you all. The suspension kit I bought is not a racing setup but it will be a huge improvement over the worn out stock components. I don’t plan to race, just cruise so I’m going to stay stock and simply replace the worn rubber with nice new part.
Thanks a million
Paul

Webineer

I forgot, the spreader bar I have read multiple threads that all swear by them. I plan to add that to the list as well.
paul

OldCarBum

You will be happy, have fun.

2airtime2

I was wondering how stronger A arms helped knowing how much our stock frames bend. Then a couple of you mentioned "spreader bar".


What is that and where does it go? Strengthening one part of the suspension doesn't make a whole lot of sense to me but making the whole car stronger does.


Nevermind, I just did a search. Now my search is on for a spreader bar for my '80. Too many on here have raved about them, I gotta have one.


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Just ordered my spreader bar from Ecklers thru Ebay, $100 free shipping. Do I just install it, adjusted out til snug, thereby eliminating any additional sag? Or is there a spec somewhere so I can adjust the length to reposition everything back to factory specs? Maybe it comes with instructions??? That would be nice.

OldCarBum

I haven't installed mine yet. I believe that you just make sure all your alignment is fully adjusted, then hand tighten by twisting the bar snug between the mounting points, then tighten the locking nuts. I read in a couple posts that some, once snug twist the bar back about 1/2 to 3/4 turn, then tighten the lock nuts. Check the installation instructions that should come with it.

jb78L-82

Once installed, tighten the spreader bar with the weight of the vehicle on the ground. You will need a wrench to tighten it sufficiently...not overtight but not hand tight.....snug with a wrench

Mine has been on the car for about 8 years now.........

71coupe

In my opinion, replacing the front upper control arms with increased caster is one of the best things you can do to a C3. They drive so much better with 6 degrees of camber vs stock 2-3/4. I can take my hands off the wheel at freeway + speeds.

These are the ones I installed. Note, your spreader bar wont fit these, & you will need power steering. I don't think spreader bars are worth the money.

http://www.vansteel.com/index.cfm?fu...p=3044&ID=3697

Other than that, my suspension is all stock with OEM rubber bushings & no rear sway bar.

My front alignment is set to VB&P advanced street specs, but with 6 deg pos caster & 1/32" toe in. My rear camber is .75-1 neg.

There will be a slight variance on each side when doing an alignment, they wont be exactly the same.. One side will be slightly less. Back off the other (high) side to match the low side.

GUSTO14

Paul, it would be useful to post a link to the kit you purchased. The actual components included and quality of them varies widely between vendors. This would tell us exactly what you'll be working with and how appropriate it might be to go to adjustable control arms, rather than just rebuilding the ones you have.

As for the spreader bar, if the car has recently been aligned you do not want to adjust the bar beyond what jb78L-82 suggested. To do otherwise would necessitate another alignment. What the bar really does is stiffen the frame between the left and right upper control arms. The normal movement of the control arms as the car travels over irregularities in the road actually result in a certain amount of flexing of the frame where the control arms attach. This results in some amount of undesirable variation in the alignment specs. By stiffening the frame in this area, the alignment specs become much more stable, and handling becomes more predictable.

Good luck... GUSTO

Webineer

I got this kit from Mid America
http://www.mamotorworks.com/Corvette...ystem-618080-1
It ticked all the boxes I was looking to address. I also went out to Ecklers and got a spreader bar for $89.
Once it is all together I will post some pics and let you know how it rides.
Paul

GUSTO14

Paul, I purchased a similar kit more than 20 years ago from a different vendor for my 1973 convertible. I was autocrossing it at the time and was very pleased with the results. I did rebuild my upper and lower control arms and used poly bushings. I had access to a pretty sophisticated hydraulic press at the time which made the job much easier. I bead blasted all the components and then primed and painted them. I wouldn't say that buying new, adjustable control arms is a waste by any means, but I also don't think you will need them to get the most out of what you have either. If you want them and have the funds, by all means go for it.

If you decide to rebuild your current control arms yourself, do be careful when removing and installing the bushings. You can twist and bend the control arms if you do not support them correctly while R&Ring the bushings. If you're not comfortable doing that on your own, by all means take them to a good machine shop and let them do it. The cost should still be less expensive that buying new.

Also when installing the spring on the differential, be sure that there is room for the bolts they have provided. If the front two are too long they can bottom on the blind holes and can punch through the housing. Most folks will also tell you not to torque the spring bolts until wheels are on the ground and the weight of the car is on the spring. With the fiberglass springs this is not nearly so critical as they don't have nearly the arc unloaded of the metal spring. It's still probably a good habit to practice however.

Good luck... GUSTO