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I just ordered a 3.5 suspension kit from them, UMI. I didn't order the front brace because I saw one from another company I like better. SC&C if I remember correctly. It ties the frame rails together and attaches to the crossmember under the oil pan. I am either going to make one like that or buy that one.
As a structural engineer, I can tell you that the only "improvement" you will get from that brace is a weight reduction because your wallet will be lighter.
This part does exactly NOTHING for the car. Think about this. It is bracing across the sway bar mounting points. These mounting points are rubber and there is NO LOAD carried crossways in the frame from those attachments. This brace is so compliant as compared to the factory frame as to be completely worthless, and the oversize holes that mount it using the sway bar mounting bolts carry no load. This is the stupidest part I have ever seen. What a crock.
Again, exactly what loads or deflections are that brace supposed to be resisting? There isn't exactly a load on the center of the crossmember, and that brace looks impressive but I can't see where there are any load paths that use it. The GM engineers weren't stupid when they designed the chassis. They analyzed the suspension loads and designed the structure to accommodate them. That's what engineers do.
The other thing you need to understand is the difference between stiffness and strength. Improving the stiffness of the chassis is a worthy goal to improve handling. The torsional stiffness of the A-body can definitely use improvement. The problem is that the load will always take the stiffer load path. Any bolted joint has slop, which makes is inherently less stiff than a welded joint. The result is that no bolt-on brace will carry load like the welded factory frame. Now, if you were to weld a brace on so that there were no bolted joints, it would provide some benefit. Unfortunately, the flat brace in the link above simply prevents the frame horns from deflecting side-to-side in the plane of the chassis. It does almost nothing to improve torsional stiffness - it just isn't designed in a way that will help that. As currently designed, it does a REALLY good job of making sure the bumper doesn't deflect side-to-side.
The rear comtrol arm braces are the only parts in that link that add value, and these are just beefed up versions of the factory-installed braces used on big block cars. I have no idea what the rear shock brace does, but again, what load is there crossways at the top of the shocks?
These alleged suspension houses need to hire some structural engineers. This is why Herb Adams was such a standout. He WAS an engineer and worked magic with A-body and F-body suspensions.
That is about as useless as the other brace they make. There is already heavy cross structure connecting the frame rails that this and the front brace are trying to reinforce. I can see using a doubler plate at the rear shock mounts as that area is prone to cracking over time. I asked the UMI rep on another site for documentation to support their claim, they had none. In my opinion they are just pretty bling.
Awesome, some good info, thanks Joe. I have replaced both upper and lower A-frame bushings and the rear trailing up bushings. I did notice some improvement. The improvement I noticed more then anything was adding the rear sway bar.
Awesome, some good info, thanks Joe. I have replaced both upper and lower A-frame bushings and the rear trailing up bushings. I did notice some improvement. The improvement I noticed more then anything was adding the rear sway bar.
Appreciate everyone's input, Joe
Ensuring that all worn or damaged suspension parts are replaced with new is the most important part of "improving" handling on a car that's half a century old. Unfortunately, many people do that in conjunction with these aftermarket "upgrades" and then attribute the improvement to the expensive aftermarket parts, when actually it was replacing the worn stock parts that made all the difference.
I would agree Joe. My suspension was completely worn out and I felt like that was the best time to replace everything. No A-frame bushings left at all. If everything had been nice and tight I would have spent my money elsewhere. But one thing, these frames and suspensions were not engineered the same way today's are. They were engineered more by trial and error. The new suspensions correct the engineering mistakes made in the 60's and 70's.
That is absolutely untrue. The problem with the suspension geometry on the 60s cars was not the engineering, it was the philosophy. Roll center and caster angles were selected for smooth ride and ease of steering - even with manual steering. These cars were absolutely engineered with the best tools available then. Of course the computing power and modelling tools are far superior now. but the older cars were NOT designed by "trial and error".
I've said this many times, assuming the suspension is not worn, crank in as much positive caster angle as possible (3-4 degrees, or more). You'll be amazed at the difference in road and steering feel on an older car.
I have the front brace on my Cutlass. I installed it with the understanding it helps during high-load steering situations. Every action has an equal & opposite reaction, so any force the steering box is putting out while corning, the box itself it putting the same force into the driver side frame rail. Connecting the rails together close to the gear box "should" then share the load equally with both frame rails. Yes I know the big metal from bumper ties the frame rails together. For the price and I was already having some other frame work done on the car, I purchased the brace and had them throw it on.
I feel this brace does nothing to strengthen the frame from moving/twisting movement during suspension travel.
I am not an engineer.
Last edited by Mr Nick; September 7th, 2017 at 06:00 PM.
Apparently neither are the people who designed this brace.
The load will react through the stiffest load path. That brace is much less stiff than the other load paths and will provide nearly no benefit. Again, the engineers who designed the frame knew what the steering reaction loads were going to be and designed for them. All this brace does is add weight with no real functional benefit.
September 2nd, 2017, 06:17 AM
