Flat Out Engineering

[STOCKISH]

Hey guys, I have a 54 Im putting together and was interested in the Flat Out crossmember for the C4 front IFS. However, it is out of my price range and it looks like it could be made pretty easily. I was going to just take a bunch of measurements from my C4 front IFS clip I have but would love to have the dimensions of a Flat Out crossmember as well to compare to. If anyone has one they would be interested in sharing the dimensions from I would really appreciate the help. Thanks ahead of time guys.

[FarmerSid]

I'm in the same boat. I'm trying to find the same info for the same reasons. I will update you with what I come up with.

[fabguy]

I am in a similar boat and would love to have all the measurements to fabricate my own. I did take some measurements from a C4 I have here and figured out that the rear body (in front of the rear tires) will be about 12" off the ground at the rear of my wifes suburban. I would prefer it to be 9-10" and am not sure if I can pull the rear brackets up a bit as I don't fully know how far they hang below the bottom of the frame.

This is from progreesive's site.
Our 1984-87 C4 Kit Tech Data:

11” brake system, clears most 15” Aluminum wheels

58.5” Hub width

Ride Height Data: Center of wheel is 1.5” above the bottom of the frame.
http://www.progressiveautomotive.com...acket-kit.html

hope this helps

[STOCKISH]

Thanks guys. I would like the dimensions of the actual front crossmember itself ideally so I can build my own as well. I would love to buy one but feel I could spend that money a lot of other places. I have plenty of 2x4 steel and welding is not a problem so I figure its worth a shot. Anyone have one they would be ok measuring and sharing info from?

[STOCKISH]

Anyone? Would consider buying a crossmember from an abandoned project pending pricing.

[Number 9]

Get a cross member with all the suspension on it. I have built c4 subframes and it was ok for me as I have done a lot of fab work. To get track width measure and adjust pivot points. You will have to notch the frame for steering rack and get the correct geometry to get the Akerman effect right. Corvette runs a deep 4.5 inch backset on the wheels so if you put 3.5 inch backset wheels it makes the tread width 2 inches wider then stock corvette. That also changes the Akerman. Otherwise do your home work.

[FarmerSid]

Number 9, "Otherwise do your home work" is a bit harsh don't ya think? Part of doing "home work" is asking questions. It would be easy to measure a flat out cross member and duplicate it if someone had one to share the dimensions with. I don't know if I'd be so quick to buy from flat out, measure it up and post it all over the net. A lot of work went into what flat out came up with and I can appreciate that. Me, I have the stock C4 cross member with everything on it so I could measure it all up and come up with a cross member design of my own for my own use. I'd have no problem sharing what I come up with as long as it's for your own use and not to make money off of my design. I could only enforce that so much so I would have to be selective in who I share my info with. I've chatted offline with a few members from here and they have been more than helpful and willing to share. That's what it's all about. I have no intentions of cutting into flat outs market. I can't afford what they offer so I have to come up with something on my own and that is what I am going to do. I am not in the stage yet of my build to start making my cross member but when I am, I will post on here how I did it. Maybe a bunch of us will put our heads together and come up with something. Who knows.

Number 9, Since you have built C4 subframes, do you have any info for those that want to build a cross member other than "do your home work"?

[fabguy]

Myself and another member here were discussing ( awhile back) purchasing both front / rear and sharing the cost to copy them for us.

[Number 9]

You don't build a crossmember as much as you make the parts and box your frame. I wasn't trying to be harsh. I was trying to help. I gave you some information I think you need. If I were approaching building it I would leave the parts on one side of the crossmember and take the a-arm spindle assembly off the other. I would think you would have to narrow the tread width some. I'm sure you have seen the flat out upper a-arm mounts and noticed the back of the upper a-arm hole is lower then the front. The purpose of this is anti dive when you brake. If you mirror the mounting points of the a-arms and steering rack it will work. The steering rack pivot joints have to line up to the upper and lower a-arm pivot points. Akerman effect is when you turn both wheels turn and one doesn't skid. The direction you are turning the wheel is at a greater angle. This is adjusted by moving the rack forward or back. It takes a bit of doing to get it right but worth it in the end. Don't forget from the start measure and record and draw. If you have single piston calipers 15" wheels will work. I think up to 1988. After that you need bigger wheels for the dual piston calipers. Any other Questions I can help with I would be glad and try to help. I say go for it. You don't need to be ready to do it to start making parts. The lower crossmember would have the lower arm pivot point's and the motor mounts and the uppers would the upper arm plates welded to the top of the frame.

[STOCKISH]

i have the complete front and rear assemblys from the C4 donor car. Both are still totally together and I have no problems taking measurements as I stated in the first post. What I was looking for is Flat Outs measurements to compare mine to. Maybe they have done something slightly different with the ackerman angle based on the longer wheelbase of the truck vs the Vette. Who knows, thats why I was asking. And as far as I recall, asking questions is part of doing my homework. I also cant afford Flat Outs crossmember (well, I can but dont want to) so I figured I will build my own. If I do, and it works as I hope I will share any and all info with whoever can use it. Im not trying to build 20 crossmembers and jump in their market, just one or two for my stuff.

[Number 9]

You can do it. There was a flat out for a ad truck on cl a few mos. ago out of Fresno I think. Not worth mentioning now but they are out there. Good luck with your project.
Your truck in the avatar looks nice.

[FarmerSid]

Josh. If you want to work together on building one, let me know. I have a C4 IFS from a 1990 to go by. It's still altogether with rack. Hopefully Number 9 will chime in with his experience as it appears he knows what he's talking about. I may have a line on getting the stock cross member digitally measured so I will see how that works out.

[STOCKISH]

Sure man, just let me know. My front is still totally together so I will jump on it this weekend. Number9, I wish that truck was mine, maybe one day!

[1949 gmc project]

How's it going I'm also like many I see are looking for ideas how to make a crossmember to fit parts from a corvette. Like everyone else on this thread I'm also on that boat I'm going to flat out engineering business in orange county to purchase the crossmember straight from mike he said he could cut a deal if I pick it up in person or if I place an order over 3k or 6k I do not recall. I well keep everyone posted on (some) helpful mesuments cause it's true flat out put alot of time an money making this product right so it would be cool to copy the complete kit or is it

[1949 gmc project]

Bobco auto.com check this site out he explains some what how the corvette suspension works

[1949 gmc project]

I ment wouldn't be cool (my bad)