triangular four link & 72 firebird sub frame on a 56 chevy truck
 

any thoughts on installing the triangular four link & sub frame under the 56 Chevy truck. I have a disc brake rear end out of a 09 ish Camaro. Its 65" wide. The old six lug is 62". the four link will give me clearance to bring the wheel closer to the frame. I believe this will work. Up front I seen the sub frame welded straight to the frame & under the frame both make it sit low. Any thoughts & ideals on this? thanks!!

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

I'm confused what rear end you are talking about, as an 09 Camaro uses an IRS. If you mean '99, then, sure - but be aware that you can put those brakes on a different / narrower 10 bolt, too.
The front sub frame... I'm sure it's been done with great results but it's been done poorly, I'd say, at least as often. You don't want it welded in cockeyed even a little bit, and you want good welds in there. Not "That should stick.."
In addition to execution concerns, the '72 Camaro sub frame is a ~45 year old design. Yeah, it's better than the kingpin shenanigans that came under a '56 pickup, but you can aim higher. If you want to spend the money you can update the Camaro spindles to something using 2004-ish Corvette bearings and brakes and with improved steering geometry, which isn't a bad way to go

but to me, if I was going to the trouble of serious frame mods to improve handling / performance, I would be looking at (in no real order)
A kit that puts C4 Corvette suspension in the car
Industrial Chassis' Dakota based kit (brakes / spindles still old school but it's rack and pinion, too, and you could use Viper spindles / unit bearings / brakes)
A Crown Victoria front clip - less fabrication than the Camaro junk, rack and pinion, much better brakes. Tad wide but not a big deal.

Orr, by the time you take the body off, cut part of the frame off, weld another frame stub in, fabricate body mounts etc... why not do a frame swap onto a newer pickup frame and take advantage of the lowering parts available for them? C10, square body, GMT-400 - it's all been done, they are all built on newer or comparable vintage design work as the Camaro clip, they are all heavier duty than the F-body (if you intend to use your truck as a truck, that matters)

Etc.

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

My $.02 is the triangulated suspension is a good choice for that axle.

I 'm not an MII or Camaro clip fan. Most Camaro clips look like an after thought when not kept short and spliced instead of laid up under and welded.

I much prefer the Kimbridge front clip, is a slide in clip. lop off your existing front clip and slide this one into the rails line it up and weld it. You don't even have to take the sheet metal off to do it. In fact it lines up easier if you don't.

It uses S10 G-body parts, which are a dime a dozen anywhere. down side the clip is about $1200.


This one has a unsteer G-Body rack Wilwood disc front and back. On the rear I did a swing arm or truck arm suspension, about $1450 without the rear end

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

I believe its a 99 it was given to me when I bought the truck. I kind of like these other options with the corvette. yossarian- your saying I can buy bigger corvette rotors & calipers to fit the spindle on the sub frame? I like you others options too about another frame.

DWCSR- I don't yet which way am going I picked up the sub frame recently but haven't tore it apart yet. a lot of head scratching too! thanks for this info it gives me a light at the end of the tunnel!!!

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

As much as I respect your work Dave, that steering setup looks like it might have a lot of bind up built into it.
The cost of the rack alone would pay for the Industrial Chassis crossmember and refreshed Dakota donor pieces with manual or power rack and the brakes and shocks with change left over. I Can't find a viable link for Kimbridge but I see well over 1K in that front end plus another 1400 for the unisteer plus another 2 or 3 hundred for the G body donor pieces.
Sorry but I see far too many $$$ in that for most guys when there is a simpler way.

On welding on a Subframe, I have done it twice with great results in both situations. First on my 48 and then on my 51 Merc coupe. Both would run down the big long roads at 80 straight as an arrow and drove great around town and rode great. That said it is 70s/80s hot rod technology from when we didn't have much else to work with. Add to that on most AD or TF trucks you are going to have to do some serious trimming on the inner fenders, change the radiator support and maybe even run a different style of radiator to make them work . Then you run into that thing of getting the sheet metal to line up and figuring out how the hay you are going to mount the front bumper.

On that 4th gen Camaro Rear, even the Camaro boys aren't found of them. They are as wide as a mid 70's C10 rear and on most rigs the tires will be outside the rear wheels in a redneck 4x4 fashion unless you run some rather ugly positive offset wheels.

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

[QUOTE=mr48chev;8055371]that steering setup looks like it might have a lot of bind up built into it. QUOTE]

not sure what you mean "built in bind up"

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

Maybe the angles will be smoother after it is all hooked up but it just does not look like there is going to be a smooth transition from the column to the rack.
The whole setup looks like it was designed to use a Saginaw box mounted to the inside of the frame rail and standard G body steering links with maybe longer tie rod ends or sleeves if needed. I can't find any link to the maker of the crossmember to find that out even though it does appear they make several setups for different rigs.

If it were me I'd notch the crossmember with a piece of tubing or rounded piece of steel to straighten out some of that steering link.

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

The subframe welded under the stock frame makes the truck sit lower than the subframe blended into the stock frame. I did the camaro clip on my truck. I plan on a parallel 4 link when I get to mounting the rear end. I went with a 10 bolt Posi out of a 78 Firebird to match my camaro front clip. The width is almost exactly the same as the truck rear.

To pick up on what other's have said:
- Yes, it does require a fair bit of welding
- you will need to figure out the core support and trim the inner fenders.
- You will need to figure out a way to mount the front bumper.

With that said, I choose the camaro clip because it was the most economical option for me. I like the challenge of fabricating all these things and making it look like it belongs there. The steering linkage is almost a straight shot to the steering column.

I wanted to keep an old school look to my truck and did not want a steering rack.I also like the fact that parts are easy to come by and if I every want to upgrade there is alot of aftermarket support for the 2nd gen camaro. I also like how much drop I got using this method ( 6+ inches ).

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

Good point, I believe the recommended maximum u-joint operating angle is 35 degrees.

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

I know that there are higher quality/newer technology crossmembers out there, but you have to pay for them. I think that an F-body sub frame is a pretty good option. I used a '79 subframe in my '59 Apache and am happy with the outcome. The No Limits DVD is well worth whatever Rob @ No Limit Engineering charges for it and will pay for itself many times over in time saved. I personally am not a fan of welding the sub frame to the bottom of the frame, as it looks liie a blatant after thought. Lower, yes, but I would rather spend the money on a set of drop spindles and or springs/bags and have a cleaner graft. I think that triangulated 4-links are the way to go. The satchel links are also worth looking into. Depends on what you want to do with the truck. A parallel 4 link would probably be easier to fabricate and perhaps a little more forgiving than designing your own triangulated 4 link, as far as fabricating mounts goes. Good luck!

Nik

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

One of my running buddies has done about 25 subframe jobs over the past 20 or so years.

Here is how he does it. This puts the truck real low but by blocking the subframe off the shop floor at stock Camaro ride height (about 6-1/2 inches give or take) and blocking the frame up behind it at the static ride height you want it to be at when you are done you can end up with the desired ride height with stock springs and spindles. I did my 51 Merc that way and it came out exactly where I wanted it. A bit of compensation for tire height might be in order if you are planning on real tall tires. Cutting the back end of the subframe rails off and butting it into the frame might be cleaner but this method gives a full solid frame that isn't going to fail. Note that the frame rails and the subframe rails are exactly parallel. This is an absolute must when you do a subframe job no matter what some self styled experts expound about adding caster by tilting the subframe. The guys that say that never built and drove one.

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

I see what your talking about, The steering shaft isn't fix to that position its just laying there, We put it on so we could get an idea of where it would go when the engine is set in.

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

hey dwcsr, does that rack set up give bump steer? by the pics it looks like the inner tie rod pivots are pretty close together compared to the control arm pivots. might be the pics though. that front and rear set up looks beefy.

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

I think its the angle of the picture. when I lay a straight edge on the upper and lower A arm bolt pivots it does intersect the tie rod pivot. this picture is a little better

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

dwcrs, do you think the steering shaft will eventually line up better when finishing or will you need a c notch in the cross member maybe?
looks like a tough built unit overall.

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

The angle as it is is to tight so we will do something with it once we get to a column placement and the engine is set. but like I said its just laying there at the moment. The lower angles are fine but may not be the final placement.

Re: triangular four link & 72 firebird sub frame on a 56 chevy truck
 

isn't it nice working with new stuff? clean, straight, haha.