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Has anyone purchased this item on here? I have a 1972 Cutlass that is getting a substantial power upgrade and would like to support the weak frame as much as possible.
As an aerospace engineer specializing in structures design, I fail to see the benefit of adding that. It does nothing for bending and any improvement in torsional stiffness is negligible compared to the weigh increase. If you are making a "substantial" power upgrade, weld in a properly designed cage that improves both bending and torsional stiffness. You want a 3D truss, not more rungs in a flat ladder frame.
Outside of boxing the frame I see no advantage. I also don't understand why they are making a solid connection to the floor as the rest of the body is isolated with rubber pads to allow flex.
As an aerospace engineer specializing in structures design, I fail to see the benefit of adding that. It does nothing for bending and any improvement in torsional stiffness is negligible compared to the weigh increase. If you are making a "substantial" power upgrade, weld in a properly designed cage that improves both bending and torsional stiffness. You want a 3D truss, not more rungs in a flat ladder frame.
Yeah, that is what I was probably thinking. The car is a convertible and it will be for street only, so maybe I won't need it, but I just wanted to prevent any long term damage with the added torque. Won't be adding a cage.
Originally Posted by oldcutlass
Outside of boxing the frame I see no advantage. I also don't understand why they are making a solid connection to the floor as the rest of the body is isolated with rubber pads to allow flex.
Yeah I didnt really like that idea either. Crap!
Are there any other ideas besides a totally new chassis? I can't afford that!
Add bars from the cowl to the front of the horns. Of course that might just rip the cowl apart if you don't make it a real cage.
You won't damage the frame, or at least, certainly nothing that the "reinforcement" kits help. Those kits are (hopefully) to improve suspension performance. Actual "damage" would be things like the lower front control arm mounting cup ripping off the frame, the rear shock mount tearing, body mount points rusting through, etc. None of which are addressed by kits. Just go over your frame with a fine tooth comb and make any necessary repairs.
The rear bars that go from the forward lower control arm mount to the upper control arm mount are generally useful, also cheap and easy to install.
Those kits are (hopefully) to improve suspension performance.
Except that they don't. The only thing that kit does is increase the bending stiffness of the frame rails in the direction parallel to the road surface. There is virtually no load in that direction, so deflection in that direction is not an issue. The biggest problem with the A-body frame, especially with a convertible, is torsional stiffness. This is what causes cowl shake, and also negates suspension functionality and handling as the frame and body deflect torsionally. Unfortunately, the only effective way to increase frame and body torsional stiffness is with a 3D truss (ie, a cage). Ladder frames just suck in resisting that type of loading - especially with rubber body mounts tuned for low NVH, not for stiffness. This is why monocoque cars are so much stiffer than body-on-frame cars. The extra depth of the body from the floor to the roof is essentially a big torque box.
Add bars from the cowl to the front of the horns. Of course that might just rip the cowl apart if you don't make it a real cage.
You won't damage the frame, or at least, certainly nothing that the "reinforcement" kits help. Those kits are (hopefully) to improve suspension performance. Actual "damage" would be things like the lower front control arm mounting cup ripping off the frame, the rear shock mount tearing, body mount points rusting through, etc. None of which are addressed by kits. Just go over your frame with a fine tooth comb and make any necessary repairs.
The rear bars that go from the forward lower control arm mount to the upper control arm mount are generally useful, also cheap and easy to install.
Thanks. I have completed full UMI suspension and chassis parts, including the parts you listed above.
Originally Posted by joe_padavano
Except that they don't. The only thing that kit does is increase the bending stiffness of the frame rails in the direction parallel to the road surface. There is virtually no load in that direction, so deflection in that direction is not an issue. The biggest problem with the A-body frame, especially with a convertible, is torsional stiffness. This is what causes cowl shake, and also negates suspension functionality and handling as the frame and body deflect torsionally. Unfortunately, the only effective way to increase frame and body torsional stiffness is with a 3D truss (ie, a cage). Ladder frames just suck in resisting that type of loading - especially with rubber body mounts tuned for low NVH, not for stiffness. This is why monocoque cars are so much stiffer than body-on-frame cars. The extra depth of the body from the floor to the roof is essentially a big torque box.
Good to know. Looks like I'm just SOL.
Basically, the new SBO350 block being installed in the car is 530hp/580tq, dyno'd. I just don't want to tear the car apart and was hoping to do as much precautionary work as I could.
Are there reinforcement mounts for LCA mounting cup/engine mount locations to prevent that wear and tear?
Are there reinforcement mounts for LCA mounting cup/engine mount locations to prevent that wear and tear?
Joe, that's why I said "hopefully".
No. It's to prevent the lower forward mount from twisting. That mount is effectively only anchored at the frame rail, with the inside left hanging, and the mounting bracket isn't anything impressive. So the bar helps locate the inner end of the mounting bolt. And that's for suspension performance to keep the lower control arms working in the plane they're supposed to.
Seriously, you won't damage the frame from engine power. Frame damage will happen even with a 100hp engine if the thing rusts through. And if you've built the car for, say, <10sec quarter mile times, then there's a ton of other stuff going on and any frame weaknesses will already be taken care of.
If you have street tires and are driving on the street then it doesn't matter how much power you make. Most of the power will go to smoke and won't have a chance of hurting anything.
Note that there's a severe lack of quality motor mounts. Anchor (AFAIK) makes all the rubber mounts, so buy them from the cheapest place (generally rock auto). Buy extras, as some aren't made right. Took me a while to realize the mounts weren't lining up because one of them apparently wasn't in the mold correctly when it was made. It is possible, even likely, to tear the driver side engine mount, so some guys put a bolt vertically through the middle through the rubber to prevent it from ripping apart. Your only other option is getting solid mount(s) from the specialists.
Basically, the new SBO350 block being installed in the car is 530hp/580tq, dyno'd. I just don't want to tear the car apart and was hoping to do as much precautionary work as I could.
mind sharing some parts you installed to achieve that number from your 350sbo? My favorite part is the designing and testing.
Basically, the new SBO350 block being installed in the car is 530hp/580tq, dyno'd. I just don't want to tear the car apart and was hoping to do as much precautionary work as I could.
mind sharing some parts you installed to achieve that number from your 350sbo? My favorite part is the designing and testing.
Mark R from thsi forum built the engine. It's bored/stroked to 434ci!
Originally Posted by oldcutlass
There are a great many products out there that can help with performance, don't buy into some of the hype for bling.
Fair enough. I got them for free with other purchases, so figured it couldn't hurt?
If there's anything out there besides caging or buying an entirely new aftermarket chassis, let me know!
I used the kit directly from HPI. That summit is a rip-off of the HPI stuff (small company in Canada). Hopefully they're paying HPI something for the design?
Joe will tell you the same thing again. The K members are pretty pointless. The boxing bars are useful if you have a hard top frame.
I still like it because the trans cross member gives you more flexibility than the stock and the exhaust mounting points are nice. Also a built-in driveshaft loop. There's still a ton of nose droop from where the front section meets the main frame rails.
My particular combo still required trimming the rear crossmember so the exhaust cleared under it, and I had to drill some extra holes in the trans member due to my trans and pan combo.
That's good to know - I understand there's only so much (or little) a ladder-frame can accomplish for torsional stiffness. But, I figured every bit helps unless it literally doesn't do a thing...
Saying that, what are some proven ways or ideas to strengthen the front section (where it meets the frame rails), since that is where the engine will be torquing the most? Triangular strut tower brace?
Again, the only thing that makes sense structurally is a 3D truss. There are front frame bars like this, but unless you have a cage inside the car for them to attach to, they won't do anything. You certainly can't just bolt them to a sheet metal firewall on a body that is mounted on rubber bushings.
Saying that, what are some proven ways or ideas to strengthen the front section (where it meets the frame rails), since that is where the engine will be torquing the most? Triangular strut tower brace?
The A body front suspension is down low, so no need for tower braces like you see on Mustangs and similar cars. Some larger GM cars have braces that run from the cowl to the core support, but that's really to keep the core support from wobbling like a noodle.
SC&C and a few others sell a brace that dies the bottom of the front horns together. Also quite pointless as it only, potentially, helps steering response, but only in seriously extreme circumstances.
The A body front suspension is down low, so no need for tower braces like you see on Mustangs and similar cars. Some larger GM cars have braces that run from the cowl to the core support, but that's really to keep the core support from wobbling like a noodle.
SC&C and a few others sell a brace that dies the bottom of the front horns together. Also quite pointless as it only, potentially, helps steering response, but only in seriously extreme circumstances.
Seriously, box the frame and call it good.
Thank you. I have an OEM boxed frame since it is a convertible - so I'll just call it good I guess.
I used the kit directly from HPI. That summit is a rip-off of the HPI stuff (small company in Canada). Hopefully they're paying HPI something for the design?
Joe will tell you the same thing again. The K members are pretty pointless. The boxing bars are useful if you have a hard top frame.
I still like it because the trans cross member gives you more flexibility than the stock and the exhaust mounting points are nice. Also a built-in driveshaft loop. There's still a ton of nose droop from where the front section meets the main frame rails.
My particular combo still required trimming the rear crossmember so the exhaust cleared under it, and I had to drill some extra holes in the trans member due to my trans and pan combo.
HPI makes the kit and sells it under the Summit brand, Summit did rip it off. HPI mentioned this on their Instagram when about 6mos before Summit started selling it.
You are overthinking this. That engine will not tear apart your car, especially the convertible frame. The engine in my Chevelle puts out way more than that on a stock non convertible frame that’s been boxed. The frame is probably still weaker than convertible frame and it’s been just fine for years.
Unless you are planning going to the track often, just don’t worry about it. There are plenty street cars out there making way more power on stock frame without issues. You won’t have enough traction to break anything. JMO.
1972 Cutlass Frame Brace Kit?
