How to put the front clip back on after a subframe?

hey guys,

weve all gone threw the "how to subframe/swap frames" thing a million times but something i havent realy seen all that much information on is how to reatach the front sheetmetal groupe.

just for the hell of it lets use late 40s early 50s cars for examples. do most of these just bolt together and then just anchor them to the firewall and the radiator suport or???

pix would help

tia
tim

 

It's all about lining up the sheet metal nice and straight.

Try putting the entire car up on stands so that you have anough room left to be able to crawl under the frame and work. Put a level to it so that you have a good reference point for measurements.

Then bolt/clamp/prop-up/duck tape/whatever all the front clip up to where it more or less belongs - stand back - way back if possible, and give it all a good eyeballing and keep working to get everything - body lines - gaps, etc. to line up perfect. Take lots of measurements, make sure it is all just right. Then crawl under and see where the best places are to make new support brackets/tabs and tac weld them on.

After you have it all tacked in enough to support the clip, remove all the clamps, props, duct tape etc. do more eyeballing and measuring and final adjustments before finish welding.

 

Most of the GM cars that typically get subframed originally had all the front sheet metal mounted to the radiator support, which was bolted to a small "crossmember" (which was really more like a spreader bar). This spreader was mounted to the frame very close to the front of the rails. Depending on which model and year, there were usually one or two bolts holding the rad support to this spreader. The sheet metal group was kept from rocking or twisting by the way the inner- and outer fenders were mounted to the cowl.

Now, looking at the subframes that get used so often, some had a similar spreader built-in, and others require a spreader to be attached to the subframe. This is often a pretty simple piece made of rectangular tubing, or by cutting the one off the OEM frame and reattaching to the new sub. On the subs that already have this spreader, you typically need to make a simple adapter bracket to bolt the original rad support to the "new" sub.

Basically, you'd bolt the front sheet metal group together, and attach it to the cowl and get everything re-aligned. You'd use a floor jack or some stacked pieces of lumber, etc. to hold the front of the sheet metal together while setting all this up. Once it was aligned to satisfaction, you'd fab the new spreader or adapter to fit the sheet metal.

Once you had the sheet metal ready, you'd have to get creative on mounting the bumper...but this was the 80's and early 90's. Everybody left the bumpers off and painted their cars to look like Easter eggs and put "I Want To Be Like ZZ Top" graphics down the sides!

There's my 1000 words, now somebody give us a picture!

 

Like they said, the location of all that stuff is usually determined by the radiator saddle, which everything else attaches to.

Easiest way is to do some work BEFORE you hack the old front end off. Take off the sheetmetal/rad support, then build a jig out of tubing/angle iron or whatever. This jig should attach to the firewall at at least 3 points, and bolt to the radiator saddle's mount on the chassis. This locates that mounting point in relation to the BODY, not the frame.

When the subframe is on, just bolt the jig back on the body, and you now have the exact location of the old rad support mount. Fairly simple matter to build a bracket off the new front crossmember that meets up with the jig.

Steve

 

Yeah, Steve, I forgot we did that on a couple cars too. Worked out pretty decent.

So is this the next street rod fad? 80s Nostalgia? Now where did I put those Centerlines?

 

Good question. And a LOT of these are done rather poorly.
Whether you utilise the original mounting style, which is the center bolt/'Y' yoke type as on Fords, or make your own using two mounting points as a late-model, you MUST mount with rubber and shims.
Why???
Because you are not going to be able to weld the mounts that perfect that you won't need a shim or two to make it line up perfect, AND the rest of the body is mounted with rubber. If you mount half the body in rubber, and half solid, can you guess what will happen after a couple three good potholes??
It's called doing crack, and it's bad, mmm Kay??
What I do is fab it up as stated (I prefer to utilise the original if at all possible), then add a couple shims and my rubber insulator (cut a piece from an old tyre's tread), then I aim for as close as possible, knowing that I have a couple shims I can subtract, if too high, and I can always add a couple if I'm too low.
Cosmo

 

[ QUOTE ]
Like they said, the location of all that stuff is usually determined by the radiator saddle, which everything else attaches to.

Easiest way is to do some work BEFORE you hack the old front end off. Take off the sheetmetal/rad support, then build a jig out of tubing/angle iron or whatever. This jig should attach to the firewall at at least 3 points, and bolt to the radiator saddle's mount on the chassis. This locates that mounting point in relation to the BODY, not the frame.

When the subframe is on, just bolt the jig back on the body, and you now have the exact location of the old rad support mount. Fairly simple matter to build a bracket off the new front crossmember that meets up with the jig.

Steve



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And if you add a little more planning you can add the bumper mounts to the jig and everything bolts up the way it was intended.

 

[ QUOTE ]
Easiest way is to do some work BEFORE you hack the old front end off. Take off the sheetmetal/rad support, then build a jig out of tubing/angle iron or whatever. This jig should attach to the firewall at at least 3 points, and bolt to the radiator saddle's mount on the chassis. This locates that mounting point in relation to the BODY, not the frame.

[/ QUOTE ]

Crap, I wish I had read this a month ago. Thats some great advice. I'm swapping frames, but the idea is still relevant to that type project, too. Looks like I may be putting my cab back on the Stude frame so I can do the "front clip mounting jig".

 

Good f'ing question. I have a ford truck that was subframed and when I took off the fenders they sprang off the truck they were being pulled down so hard. I guess the radiator support is too low. The back of the hood has a pretty wide gap too. . . hmmm.

That jig idea is smart. much easier than bolting it all back together twice.