custom control arms,need an opinion

[speedfreak]

hey just signed up on here i've been visiting for a while its a really sweet site, im looking for some opinions on these control arms i had made. They were made by a well know suspension shop up here in Mass. the guy split the upper arms to make installing/removal easy, im just questioning the strength in a 4000lb+ car<going into a '78 bonneville, g-machine of course> he said hes done this alot, i should probably trust his experience, just wondering what you all think

[MrQuick]

ahh uhhmmm, I wouldn't run them but then again I don't run with sissors. I would have gone a little further into the arm and used 2 bolts. Or maybe a sleeve and pin design. Anyone eles?

[dennis68]

I don't know that I want to be fender to fender with the guy running those. They would probably be OK for a fairgrounds cruiser or maybe even straight line duty, I just wouldn't trust that bolt during a hard braking off-camber turn.

"POP", what was that sound sound.......Oh *****.

[Conekiller13]

Mmmmm...............interesting. I don't think it's somthing I would use in a Pro-Touring aplication. I'm also curious what the camber gain and overall geometry on that arm is. Is this guys experiance in building road race cars or dragsters or cruisers?

[David Pozzi]

That looks like circle track stuff, almost like the Pole-Position arms but not identical. It is probably OK but not what the Pro-Touring crowd is used to.

[dennis68]

I'm OK with running speedway parts, most are better constructed than the stockers. I just don't like the looks of that 1 bolt holding arm to the cross shaft. I wonder what the shear value is on the joint vs. whatever bolt that is...hardware, grade5, grade8?

I also don't like how little material seems to remain of the UCA arm itself, it seems quite a bit was removed to create the clevis arrangement.

[wally8]

I'll jump on the bandwagon and say that it's too small too. Particularly if the shank length isn't properly sized for the application which judging by the hardware store look of the fastener and lack of washers, I'm guessing it's not.

Of course my unsubstantiated opinion is as worthless as everyone else's. :-)

Put it on a race track and you'll find out very soon if it's good enough......


Wally

[speedfreak]

thanks for the imput im taking this all in..slowly learning

Heres a little background info on the arms...
i wanted to go the tubular arm /coilover route, but i couldn't find anyone who made a bolt in application for Gm B-Body's-at least not of this year-so i made the decision to have this guy build me a set using the original arms as a guide, he never told me he was going to do it this way and when i question it he showed me his car and assured me it was ok, even in this heavy of a car, i figured if he trusted it it must be ok.It is all GRADE 8 hardware holding it together

Anyway ive decided to scrap the original frame and build a 2x3 frame for it but id like to use these arms-seeing how there paid for- just need to figure out optimal mounting points, as opposed to stock...at this point having them modified to a standard solid arm configuration wouldnt bother me as long as it makes it strong and safe..any ideas other that going that route...?

oh yeah a few motnhs after having them made i figured out '94 t0 '96 impall/caprice arms would have fit.an a couple differnet companies make them....doh! ya live ya learn..when is the aftermarket going to embrace the beauty that is the GM B-Body???

[Marcus SC&C]

Speedfreak,out of curiosity what size are the bolts?

I`d be MUCH more concerned with the penetration of the welds than the bolts. If the welds are good I`ll bet you could shear the tiny 1/4" bolts off the UBJ before the larger bolts on the cross shaft give way.
For that matter think about the tiny thin strips of mild steel that hold the bushings in the stock UCAs. I don`t have the numbers with me at home but the shear strength of even a 3/8" grade 8 bolt in double shear is much more than it would take to bend a stock UCA like a pretzel.
As for the PPR adj. upper arms,they use bolts in the same location but in a different configuration. They`re 7/16" grade 8 bolts in double shear and the mounting ears are actually the ends of a strap that runs *completely around* the cross shaft. I`m told circle track racers often mangle the wheels and bend UBJ studs in crashes without damaging the Pole Position UCAs. When you handle a set you can immediately tell they`re very beefy and strength just isn`t an issue.
Now,they`re a mass produced UCA with a long history in both motorsports and street use. I can`t say how well the shop built UCAs being discussed here may hold up without seeing them for real but the bolts would be the least of my worries. Marcus

[Fuelie Fan]

Grade 8 proof strength = 120 ksi

shear strength for alloy steels = 0.58 * tension stregnth = 69.6 ksi

Assume 3/8" bolt with shank (x-sectional A = 0.11 in^2)

Max stress = P/A

69,600 lb/in^2 = (max load)/(2*0.11in^2) (the two is for double shear)

Max load = 15,300 lbs.

[dennis68]

ah nevermind

[speedfreak]

alright, i found a link in a old post about the Pole Position arms...nice setup wish i saw them before..anyway is the bushing side of those arms billet or is the tab welded on-like mine is- i was looking at mine and thining of machinig it out of a solid piece of steel, seeing as how that seems to be the weak link...other wise i think mine will hold up nicely..im gonna contact my guy and make sure the double tab is on the end of a plug that was inserted and then welded

[Marcus SC&C]

The PPR arms are welded BUT the steel brackets aren`t just butted against the bushing sleeve and welded on. The bracket *wraps all the way around* the sleeve. The welds really just keep them from sliding off the ends,well they add to the strength too but the real strength is in the design and not dependant upon the welds alone. Scott`s Hot Rods makes a line of street rod UCAs that use machined billet stainless units like you`re describing although I`m pretty sure they won`t work for your application. Their male and female are opposite of what yours are,like the PPR UCAs are. As long as the welds on yours are sound (and the rest of the arms that we can`t see in the pics are okay) I think you`ll probably be fine. Marcus SC&C