Bolt-in frame stiffener enough?
 

Hey guys.

I'm going to pull the current 383/700r4 and use my TSP LS7 (because the camaro project is dragging too long so may as well "borrow" it) and a built 6l80/l90. I am currently on Ridetech coilovers and sway bars front and rear. I have several of the "bolt in" tubular cross members. There is a TON of flex in the frame though. I plan to slowly get into autcrossing with the truck and have a wood bed floor (hinged) so that is working against me as well.

My whole goal is to reduce chassis flex when cornering.

I can't afford to go full bore and do full chassis, yet, so need to work with my factory rails to get me by. From what I understand, it is wise to not weld on the rails if possible so that eliminates me boxing in the rails unless bolted in.

That leaves me with basically 3 options:
Nate at porterbuilt is awesome and extremely helpful, but 50% higher than the other version (now on summit) I was originally looking at
$1500: https://pbfab.com/inner-frame-stiffe...-boxed-1-piece

I have no experience with Tin Works but they look nice
$1400: https://tinworksfabrication.com/prod...ame-stiffener/

Unit offered at summit:
$1000: https://www.summitracing.com/parts/sum-770820

Have any of you used these, and will this eliminate most of my flex or will I still need to do more? if so, where else on the frame should be addressed?

Thanks in advance.

Re: Bolt-in frame stiffener enough?
 

first 2 links don't work for me, Summit one does

My $.02 is the bolt in is fine assuming the holes are dead nuts (read not bigger than they need to be). Welding after bolted would likely add some more stiffness...if measurable (read butt-o-meter may not be sensitive enough to notice)

Re: Bolt-in frame stiffener enough?
 

Sorry about that, try this one
https://pbfab.com/inner-frame-stiffe...-boxed-1-piece

And this one
https://tinworksfabrication.com/prod...ame-stiffener/

I'm thinking about trying to connect the front rails to the firewall too, if it'd help at all.

Yes I agree that any "slop" in the bolt holes is no good and needs to be as "on" as possible.

Re: Bolt-in frame stiffener enough?
 

Short of going full custom frame from someplace like the Roadster Shop or Art Car...any of the 3 frame stiffening kits will provide more frame stiffness to a stock frame. How much of a difference, if any, between the 3 IMHO would be a fine line

Yeah firewall to front frame triangulation is also going to help

Re: Bolt-in frame stiffener enough?
 

Why are you set on using a truck platform? Why don't you spend the money on a more suitable base and use the truck to tow your new race car?

Re: Bolt-in frame stiffener enough?
 

I doubt it needs to be said, but road course/autocross and pickup truck are kind of oxymorons.

As such, if this is for anything other than fun, the prebuilt chassis are really the only way to be competitive, considering how far the other vehicles in the field have come.

That being said, the cheaper option will probably give you the most bang for your buck, and the more expensive options may have the law of diminishing returns playing against them.

Think of it like sound deadening. Covering 25% of a panel will give you the most benefit for the cheapest amount. Adding more sound deadening is adding significantly more cost vs reward at that point.

Adding a frame stiffener on a stock chassis makes a massive difference. A more expensive option may have calculated the absolute best weight, material, balance, and stiffness, which may gain you a small amount of benefit. However, you're still limited to that stock chassis and all of its drawbacks to begin with, versus a better-suited chassis option.

Re: Bolt-in frame stiffener enough?
 

On my 68 I added some bracing to the frame. I made my own parts. I have a pic of the rear frame section. What you can't see is the tubing that I added from the the trailing arm to the trans cross member. One on each side of the drive shaft.
I got the idea from an article in Hot Rod magazine where they featured a 68? C10 that was modded to run on the road course. Truck was read. I do not recall year or the month of the feature.

Re: Bolt-in frame stiffener enough?
 

If this is the direction u want to go then either pb or tin works are the way to go.you need to tell us more about the whole suspension set up u plan to have . This is but 1 piece in the puzzle. The summit 1 will give you some benefit but not like the other 2. I have the tin works version and I can say it is very well made. His is designed as a bolt in due to a lot of people not have the skills or just no having a welder to weld in. I mounted mine by using the corners to bolt it n then welded the outer rail that fits inside the frame in. It was welded in n spots and not the whole length. Couldn’t see a need to unbolt it, so I thought this would help with flex as well. What you can’t see in pics on his site is each outer rail has an access panel bolted on. You could put your fuel filter setup behind it giving you direct access and not worrying about something from the rd hitting it. His tranny crossmember adjust so if u want to change out trannys n the future, it takes some of the hassle out. With Labor Day coming up I would suggest that u wait and check back on his site as he usually runs a sale about that time. You haven’t said much on the rest of the setup but if you are gonna do some auto crossing, u will need a better set of trailing arms than what came from the factory. Also….u can’t run long tube headers with a set up like this. They won’t line up with the holes for exhaust in stiffener and they will come close to touching it so there isn’t room for a flex pipe to make it work.
I hope this helps and good luck on your project.

Re: Bolt-in frame stiffener enough?
 

Any triangulation of/for the outer rails will help.
Summits version of the others is cheaper because it's a copy of one of them.

For the rear rails, some sort of gusseting is not a bad idea (the rails as well as the bed floor cross sills).

Later frame rails had heat treated steel & that's where one has to be aware & have the ability to properly weld that material. The 63-87 rails can be welded (boxed) but again one needs to know what they're doing to make it effective w/o being detrimental.

Re: Bolt-in frame stiffener enough?
 

For reference, the truck currently has ridetech coilovers, front strongarms (tubular upper/lower control arms) and muscle bar swaybar, rear CPP tubular trailing arms, adjustable rear sway bar, and rubular cross members for the shock mount and trailing arm crossmember. Wheels are 20x8.5/20x10 with 255 front tires are 295 rear tires.
I'd like to maybe rob parts from my camaro and run 335/30r18 rear and a 285 or 295 front tire on Forged wheels.



Prefect, thanks for the feedback. Tin works and PB have similar designs so between the three I'd imagine those two would offer about the same, if not more than summits.



I'm petty deep into a '69 Z/28 project for this, but I could finish the truck a lot sooner.

The camaro has a full Schwartz chassis, 13" rotors with 6p/4p calipers, ls7, t56 magnum, forgeline wheels, and quite a few carbon fiber body panels.

Thanks for the feedback. I know to do this "right" it would be on a full chassis, probably one from Brian Finch or Rob MacGregor as I think everything they build gets raced.. honestly I just can't commit to one though right now. I'm already pretty deep into mine and feel like I have decent suspension, just need to get a little more rigidity.

There are some pretty dang fast trucks out there and there's something cool about making a truck a racecar I guess?


I'm going to see if I can find that, thanks!
I bet that did help a lot and can't tell for sure if these braces add support to the area you added tubing unless you ran back passed the trailing arm cross member.

That's cool you actually own one of the three and have experience - thank you! All 3 accommodate the "common" auto and manual trans options, but his does look well made.

It's almost an exact copy of PBs original style it looks like. Bummer, and I hate that for Nate.

I'm also thinking about doing some major bracing for the cross sills as well like you mentioned. I need to raise the bed floor 2in so this will be a good time to go about it.

Re: Bolt-in frame stiffener enough?
 

Traut811 I get the modifying bug. I was bit by that bug decades ago, and still have a case of the infliction to this day. I found it to be way better to pick a class you want to run in, and build to that rule book. Other wise you will find yourself modded to a point where you fit into nothing but the unlimiteds, and well, that's a money pit. If you have not done so, check out NASA Pro Racing. Very grass roots and lots of info on the site about starting out. HPDE, Time Trial to full wheel to wheel. A really fun organization. Most regions are well organized. I think the one in your area is pretty active. Best of luck to you.

Re: Bolt-in frame stiffener enough?
 

I didn't know these were a thing until I saw your post. Good timing as I was looking into getting a trans crossmember and rear trailing arm cross member so I could tuck my exhaust.

Money no object, I'd get the Tin Works stiffener, I like that it has a long single bolt in piece for the frame instead of multiple smaller pieces.

However, I'm on a budget and have nothing fancy on my truck suspension, so I bought the Summit one. I also had some Summit bucks to use, so that also helped the decision.

If it's worth anything, Summit has changed the design. They updated the picture on their site after I received mine.

Re: Bolt-in frame stiffener enough?
 

Thanks a bunch for the reply!
I still haven't ordered one yet.
Does it look like HPI still makes them for Summit? Does it still include the motor mount stands? No damage upon arrival?

Please keep in touch when you install, curious how it all works out.

Re: Bolt-in frame stiffener enough?
 

What was changed?

Re: Bolt-in frame stiffener enough?
 

Everything, looks like a complete redesign.

Still includes the motor mounts, I had one bent ear on the very front of the pass side tube-to-frame mount, you can kind of see it in the pic I posted above. The box was very beat up, it's basically just tossed into a box with no protection. Shouldn't be a big deal to bend it back.

Looks like it's still made by HPI, I found this on their IG:
"We’ve completely redesigned our popular 63-72 C10 frame bracing kit to increase floor and transmission clearance, maximize rigidity, and provide easy routing for up to 3.5” exhaust WITHOUT JOINTS that can drop out from underneath, all while tucked up for the guys who want to lay frame!"

They have a new install video for long wheelbase trucks on YT, which is what they redesigned it for. Thankfully, no music playing over the guy talking.

https://www.youtube.com/watch?v=ON7yyIwRcss

I do like that you can install/remove an exhaust without having to feed it through tubes/cutouts but I wonder if any rigidity is lost (they say it's more rigid than the previous version)

Re: Bolt-in frame stiffener enough?
 

FYI this thing won’t work with a shortened frame. The front c channel will interfere with the frame splice. I have to call summit tomorrow and probably return it unless HPI has some other option. If you did a DIY splice with a fish plate it would probably fit. The old version fit but this one doesn’t.

Re: Bolt-in frame stiffener enough?
 

Thank you very much for that insight.
Mine is shortened, but was done as a z notch with a plate welded in the center. I assume interference comes from a "bolt in" shortening kit where you go back and weld it, and a thicker top and bottom section of the frame channel causes issues?

Re: Bolt-in frame stiffener enough?
 

Some basic observations over the years with NASA. The little league of motor sports. As a instructor for NASA, I post this with all respect. Over many years i have come to observe two approaches by individuals entering into auto sport. Those who will build and build and build with little track experience. The other method is the owner/driver who develops their skill and realize early on that throwing all the hardware in the world t thier race car won't make them fast if they have not first learned how to control/drive the car. Do your wallet a huge favor. Stop all development and get the truck, car, or whatever platform you have onto the track and learn real car control. Then after you have developed the nut behind the wheel you won't need any input from us. You will know what you need to go faster.
The previous statement may sound a bit conseaded but I am telling you with 100% confidence a owner/drive who does not have at least 2 full seasons of running and loosing has no idea what it takes to make a platform fast. Anyone attempting to steer you in the direction of some aftermarket Ricky Racer product is not likely to have ever been on track.
Close your wallet to anything except track time for at least 2 years. After 2 years, be prepaired for a life of poverty because it takes a ton of cash to really be fast. This is from a national podium finisher with many regional titles to his name.
Sorry too much Sunday tequila.

Re: Bolt-in frame stiffener enough?
 

Yep exactly. Porter built looks like the only one I see that will work with a kit shortened frame. I’m wishing I did a z cut too as the kit I used was a nightmare and I would have been better off just doing it DIY.

Re: Bolt-in frame stiffener enough?
 

I'm still in the process of my build, but I bought the Summit version.
It's basically the same configuration as the more expensive ones.

Reading the reviews, there seemed to be some fitment issues with the hole alignment which didn't really concern me much.
Also there were a couple of reviews that stated that the cab wouldn't fit after the brace was installed.

During the install I did discover that some of the holes indeed did not line up correctly.
This was easily remedied with a sharpie and a milling machine.
When I set the cab back on, it fit fine with ample clearance.

I'll be running a stock 5.7 LS1 and coil-over suspension front and rear so I think it will be more than adequate to stiffen my frame.

Attachment 2268203

Attachment 2268204

Attachment 2268205

Re: Bolt-in frame stiffener enough?
 

Thx for the photos. Looks like you have the original version. So they apparently corrected the potential cab interference and in the process made it not work with shortened frame rails. Makes me question how much attention they are paying when they design these things. I kind of get it as they boxed in a longer section of the frame rail in the new version which is what is creating the problem. I'm just surprised they did it because, from my understanding, there were very few original short beds. The Tinworks version boxes the rails the entire way from trans X member to trailing arm member so would have to be modified as well to fit a shortened frame. Only one I see that would work is PFab. GSI used to make one for 67-72 but it is no longer on their site.

Re: Bolt-in frame stiffener enough?
 

Attachment 2268242
Okay, I texted with HPI who makes the product for Summit. See the attached photo for their recommendation if you have a shortened frame. I added the red marks where I intend to weld 1 inch sections to secure that portion of the channel to the frame once I have it completely test fit and centered. That c-channel is designed to slide in/out to be able to center the entire assembly within the frame rails. I might see how stiff it is and if, okay I may not weld that section just to make sure I don't screw something up. I'll post some photos when I get it mocked up and modified.

Re: Bolt-in frame stiffener enough?
 

For those of you that installed the Summit brace kit, did you mount it in the forward or rear holes?

I installed mine in the forward position as the instructions say to do for greater than 4" drop.

But, as expected I guess, it pulled the axle forward an inch and now a bunch of things are off (C-notch, spring perch alignment, panhard bar alignment, etc) and I have a feeling the wheel will be off-center in the wheel well as well.

Looking at pics of other lowered trucks, the wheel looks fine in the wheel well, pulling the wheel forward an inch just doesn't seem like a good idea.

Re: Bolt-in frame stiffener enough?
 

huh, that's interesting. I never really thought through that impact. What hole are you using on the trailing arm mount? I have Qa1 full coilover kit so my trailing arms are adjustable so I can fine tune it when I complete the install.

Re: Bolt-in frame stiffener enough?
 

I'm also using the QA1 coilover kit in the rear and I bolted the trailing arm mount in the rear set of holes. That's where the axle looks to be best centered in the C-notch that was part of the QA1 kit...
but, like bikeguy0 stated, it does have quite a bit of adjustment in the trailing arms.