C4 front conversion without taking body off

[hutchenc]

I'll preface this with the fact that I've seen Lazlo's work in person and that he lives about 60 miles from me. I've also spoken to him about this a bit so I know where he stands on this

I have a '56 2 door hardtop. It has pretty much every damn bolt-on suspension part known to man and it still handles like crap in my opinion and I don't really like the steering (has a 500 box). I have a 550 to 600 HP 420ci SBC in her with a Muncie 4 speed so after looking into what kind of abuse a C4 rear will take, I think I'll stick with the solid axle (I have an 8.8 in her, that Lazlo modded for me ). I'd like to put in a parallel 4 bar I think. But the new leafs, poly bushings, and Viking shocks are fine for now.

Anyway, my car is far enough along now that I'm unwilling to take it all apart and remove the body from the frame. I wouldn't mind pulling the motor, tranny and front clip though, no biggie.

Has anyone here done a front subframe swap (preferable a C4) with just taking off the front clip? I don't have the welding experience to do it myself...this would have to be done by someone else (i.e. I'm not screwing around with this sorta thing...I'm paying someone to do it).

[chevynut]

Chad, I don't know if we've discussed this before but I believe it can be done. I'm not aware of any of my customers doing it with the body on the frame, but I have had people ask me about it before. They just didn't go through with it.

Our clips weld on in front of the cowl body mount. We cut the frame further forward on the seamless version than we do on the 2-piece, because they're shaped differently. The seamless frames are about 5 1/2" tall at that point and the 2-piece are about 5 1/8" tall. We cut some wedges out of the frames to match them to our 5" tall main rail tubes, then we weld them back together and grind them smooth. That process would be a little more difficult with the body on the frame, but I think it can be done. We usually cut back to about the middle of the body mount or slightly further back on the seamless frames to get the contour right so the clip doesn't look scabbed on. We also install four 11 gauge reinforcement plates with 6 large plug welds on each side of the frame rail, then make the butt joint weld.

The most difficult part would be getting the alignment right without a jig, but that's how our clip customers do it. I usually recommend either building a quick temporary jig or using plumb bobs and tape measure to get it located correctly.

I would be interested in discussing this with you next time you're down my way. I would build a clip on a spare frame installed in my jig, then attach it to your frame. It would be cheapest if you stripped the car down by removing the bumper, all front sheetmetal, engine/trans, and steering box. I can cut the clip off with the suspension still on it. We could work with you so you could do it right here in my shop if you wanted to or you could trailer the car down.

Once the clip is installed the front suspension can be bolted on. If you have us build the engine mounts, the engine should bolt right up. Then you have to set up the steering shaft and you're pretty much there. All the stock sheetmetal should bolt right back on. I don't know how much of that I would want to do.

It would be nice to have a local car with one of our suspensions to try out.

Here's two of our frames with the frames matched to the clips, showing how we make it so the seam is barely noticeable. The one on the left is 2-piece and the one on the right is seamless. You can kind of see where the cuts are made but it's ground past them a bit.

[hutchenc]

Thanks for the reply Lazlo...I was under the impression that the frame cuts you made were aft of the firewall (meaning that this would be very difficult to do with the body on). I don't have a front bumper on right now so I guess that's one less step. I could probably sell all the other stuff on the car for a good clip of dough (tubular upper and lower arms, Heidt's spindles, 12.19" Wilwoods, sway bar, 500 box, rebuilt steering linkage etc).

Is there any reason I couldn't run C5 front brakes with a C4 front end? I know there are numerous places that make brackets for C4 to C5 brake conversions using stock GM rotors and calipers.

Next time I'm planning to be in FCO I'll give you a ring.

[rustay56]

Hello Hutchenc, Ive just put a Morrison rear end in my 56 chassis (sorry I havent posted the pix yet but they're in my album) and have tubular A arms top and bottom,1 1/4 tubular sway bar,CPP drop spindle and 13in disc brake kit to go on.also power rack.I was hoping for an excellent handling and steering car,(not morrison or c4 standard) but not to far behind.I also fitted a center section. Now Im no chassis or suspension expert (far from it) but my theory is that its no good putting in stiffer springs ,sway bars front and rear and radial tires to increase handling and not do something to stop that poor old chassis from twisting and transferring all that new found movement into the body.Now my question, You obviously think the front end geometry in your car is wrong and by fitting a C4 front clip this will rectify it (not trying to do Lazlo out of a sale) just curious as we have very similar front ends and I thought I had spent wisely. Look forward to your reply.Sorry if this comes across abit arrogant its not my intention.

Regards Andrew.

[chevynut]

Is there any reason I couldn't run C5 front brakes with a C4 front end? I know there are numerous places that make brackets for C4 to C5 brake conversions using stock GM rotors and calipers.

Using C5 front brakes would be a great upgrade. I believe they're 13". You use C5 rotors and calipers with the adapter brackets. I'm sure it's a lot cheaper than going aftermarket. I'll be around the house again starting about 9/25.

[rockytopper R.I.P 5-13-2017]

I would be interested in the 500 box if you sale it.
Rocky

[hutchenc]

rustay56,

I can't comment on the handling that you're going to be happy with because I think we're all expecting something a little different. I have driven a R&P tri-five with mostly stock but rebuilt suspension and frankly, it was so much better than the 500 box (which is what I have) I was pretty surprised...it still handled poorly though the steering was great. I like tight steering that requires some input...there's some slop in my completely rebuilt steering that I guess I just attribute to the linkage (also rebuilt)...I dunno. Now, the 500 box is substantially better than the 605 (I know this from experience), but I'm done changing things with the front end of my car at this point because nothing gets me where I want it to be and I think I'd just be throwing good money after bad.

All the other stuff...I dunno. The biggest difference anything has ever made on this car was simply rebuilding the steering linkage (badly worn out before I did that) and putting on a big front sway bar (1 3/8). The rest has made subtle differences in handling but I'm 100% confident that my mostly bone stock suspension '72 Camaro would just whip my tri-five in autocross so bad that one would probably assume the tri-five was completely stock or had an engine problem. The difference is that stark...it's so much so that when I have both the cars in working order (i.e. I'm not tinkering with something), I hardly drive the '56 because the Camaro is so much more pleasant and fun to drive.

I have good stuff on this car too...no ebay/chinese junk. Global West a-arms, delrin bushings up front, 500 box, Heidt's drop spindles, Hellwig sway bars (front and back), double adjustable Viking shocks, coil-overs up front, Global West rear leafs, poly bushings in back, poly body mounts, rear shock mount...everything. I run 17x8 wheels on all corners with 245/45/17's up front and M/T ET drags out back so I have good tires too...that's not the problem. There's literally nothing left to do at this point except try an R&P (which again, aint gonna happen).

I think for a cruiser, it's fine honestly. It doesn't wallow around corners or anything, it's just not very responsive. I didn't put a 420ci Dart SHP SBC in it to be a cruiser though.

I'm no mechanical engineer, but my assumption is that the geometry and mounting points of the front suspension just limit the ceiling on how far you can take the stock tri-five suspension...especially the front. If you think about it...the suspension is probably something designed in the very early 50's so hey, that was kinda a long time ago. Someone else would have to elaborate on the geometry and mounting points.

[hutchenc]

rockytopper...it won't be any time soon so if you're in a rush, don't wait

Also, I had to grind one corner of the box pretty heavily to clear my headers...I think the Dart SHP block (or the AFR 220 heads) may be a bit bigger than a stock SBC stuff because when I ran my 383 in the car, it fit fine. So, it aint perfect from an aesthetic point of view.

[hutchenc]

Lazlo...yep, I think I would go with C5 brakes. Looks like an easy upgrade...lots of stock GM parts available vs the J55 stuff from the C4 (which looks to be pretty hard to find and expensive too). If it stops anything like my '05 GTO I'd be damn happy.

[rustay56]

Hutchenc, Thanks for the reply and specs on your car.I know you said you were done throwing money at it but........
I lifted this article from an old super chevy magazine feature.It's from Doug Nordin from Global West
Camaros, Novas, and Chevelles are very popular amongst the ProTouring crowd but with the right parts you can get a Tri-Five to handle just as
well. Not a lot of people actually autocross their cars, so some basic upgrades is
all it takes to vastly improve a car’s street handling. At Global West, our parts are
designed for people who want bolt-on simplicity using the stock frame. We offer
tubular upper and lower control arms, sway bars, coil springs, leaf springs, and
steering boxes. Together, these parts substantially improve driveability and
cornering. For the best bang for the buck, upgrading the front control arms is
where it’s at. They add much more caster for improved stability and corner entry,
and change the camber curve for improved grip. Next on the list should be an
upgraded steering box. We offer a Borgeson 12.0:1 unit that has much better
steering feel and a quicker ratio than stock.

Dont know anything about borgeson box's but you need to try this or a rack then you exhausted all avenues and you can go to a C4 clip.It seems like you are so close and it's just the steering thats annoying you. Sell that 500 box to Rocky to offset some cost.If it doesn't work out you will always be able to sell all your front end parts off,they are good quality. Your not getting soft driving around in that 05 G.T.O. with the climate control on are you.

P.S If you have any trouble getting any little parts,clips ,switches or even literature for that G.T.O that might be nil stock in the U.S. I would be happy to assist,we have a large Holden dealership in my town......And I know a guy.

Regards Andrew.