Grassroots frame straightening

Hey guys, this one is new to me so I was hoping you'd have some decent advice. We need to do some chassis/frame straightening on our LeMons car (the Achieva SCX) and of course, in the spirit/rules of the event, we aren't just going to drop it off at the frame shop and have it done. We're all pretty clever guys and handy with tools, but none of us have done any framework before, so some basic tricks and tips would be handy.

For reference, the majority of chassis tweak is in the metal between the front bumper and strut tower-ish area. The car is a unibody, of course, but the engine/trans subframe attaches between the front and back of the engine bay, and the subframes locate the lower suspension mounts. The biggest question mark for us now is where to grab the metal to pull, how to pull it, and what to pull it with. Here is a list of tools we have at our disposal:

• Chain
• Tow straps
• Bridgeport
• Welder
• Hilift / farm jack
• Winch
• Trucks
• Tree(s)
• Tractor
• Front end loader on tractor

So, we have all the tools we need to make more tools as necessary if some special attachments are necessary. We have plenty of pulling power between the winch, tractor, trees, etc. I've been googling this for a while and found a lot of gee whiz $$$ frame equipment for shops, but not much on methods like using a 2x4 piece of wood and a mule or other such grassroots type ideas. We're thinking it seems logical to bolt something up to where the bumper bolts up, attach a strap of some sort to that, hold the car still (foot on brakes? chain to heavy object?), and pull on the bumper attachment point. We don't know if we need to focus the load a certain way so you don't end up stretching things that weren't supposed to be rather than pulling the bent stuff straight.

Thanks for any tips, links, words of wisdom, etc.

Bryce

There should be dimensions in the factory service manual. I doubt if a Hayes manual will have them. I know my Mazda RX-7 FSM has dimensions of basically every conceivable measurement on the car.

You have all the tools you would need, I have done this kind of work with less.

The important thing is to have the correct reference measurments. When I have done this I was lucky enough to have an unbent car to measure off of.

Plan carefully so that you don't end up bending something else while straightening a part. I usually had two or three tie down points for every pulling point.

The bent stuff will likely straighten before you stretch anything else as long as you have good tiedowns.
To straighten a tweaked rear frame rail on our miata- I chained it to the driveway using the front baby teeth and anchor bolts, chocked all of the wheels, and had my wife in the car with her foot solidly on the brakes. Then I pulled on the appropriate rear tie down hook (happened to be perfectly placed for this job) with a 93 T100 in 4L. It took quite a pull but everything dropped right back into place-was really cool!

A couple of friends did the job you want with a chain, some bolts, a pine tree, and reverse. Took backing up fast enough to get the car airborne about 5 times but it eventually straightened out.

I have use a large oak tree and chains before ,at my old house there are two trees prefectaly spaced for pulling unibody damage

Unfortunately, I don't have any advice on frame straightening. However, having put an SCX through paces on a road course, I recommend having a set, or 5, extra front wheel bearings. N-body cars are rough on bearings. Granted the car I ran was on R-comps, but it wasn't unlikely to have to replace a bearing (and subsequently an axle) or two after only a 30 minute session. I'd hate to see such a cool car finish part-way through the 24/Lemons due to a faulty wheel bearing.

Yeah, bolt directly to the bumper mount which is generally the end of the frame rail. Chain that to a tree. Chain the 'pull' vehicle to the rear bumper mount on the same side and pull in a straight line. It helps to have a no E36 M3 hammer (like a drilling hammer) and watch the 'wrinkles' as they pull out. Smack the top of the wrinkles as you are pulling, that helps straighten it quick. Beware: the 'hump' in the frame rail from the firewall may try to straighten (flatten out) as well. If this starts to happen, stop. At that point, you'll probably need to use a torch to soften up the wrinkled stuff so it will pull out before the factory hump does.

As far as measurements: use a tape measure, check diagonally from the lower control arm mount to the bumper mount on the opposite side. If you can get that within about 1/4" side to side be happy.

Alright guys, sounds fairly straight (ha!) forward. I'll look in the factory service manual to see if it's got specs on what things are "supposed" to be, but if we can't find them we can get them from another car.

kcbhiw wrote: Unfortunately, I don't have any advice on frame straightening. However, having put an SCX through paces on a road course, I recommend having a set, or 5, extra front wheel bearings. N-body cars are rough on bearings. Granted the car I ran was on R-comps, but it wasn't unlikely to have to replace a bearing (and subsequently an axle) or two after only a 30 minute session. I'd hate to see such a cool car finish part-way through the 24/Lemons due to a faulty wheel bearing.

We already upgraded to the later N-body aluminum knuckle with 5x115 hubs in the front, so hopefully we've minimized the chances of losing the front bearings. This also allowed us to use the bigger front brakes that came with the knuckles. Gotta love cheap parts bin upgrades, thanks GM! We managed to get through 14 hours or so at Flat Rock on Azenis without any wheel bearing troubles, unfortunately the engine let go with 10 hours left in the race. Hopefully we can keep the car together this time around, the car was haulin' the mail when it was running. :)

Bryce

I'm glad everyone else has had good results trying to straighten frames with trees and chains.

My one shot at it was unsucessfull. A '78 Buick Regal roundy-round car taht I managed to shorten one frame rail significantly (and make a trapeziod out of the frame in general).

We took it to a buddy's farm. There he had all the necessary (we thought) tools to tear the car completely apart (but we hoped not to go that far). To say the tractor was big is an understatement...a big understatement.

We chained the framerail to a tree, the other end to the tractor, and proceeded to pull, many times. The car looked like a ragdoll...but the frame never came straight (nor did it partially straighten, to our knowledge).

I decided that impulse type force wasn't going to do the job and we needed slow-steady pull...Hydraulic.

We didn't end up trying any other methods besides the big tractor...we just raced the car all bent up...no problem ;).

Bryce...let us know how your experiments go! I'd like to see how it works out for you.

Clem

Well, the guys gave it a shot last weekend. I wasn't around for the action, but I'll post up what they said to share our experience:

DONE! We chose the Jimmy+towstrap+locked brakes on achieva method. It worked out pretty good. Did 3 pulls with increasing speed, then added ballast to the achieva and did 3 more high speed pulls. The group here seemed pretty satisfied with the results. The section that collapsed originally has been reinforced. The original plan was to reinforce all the way forward to the bumper mount, but after a group discussion, we realize that we're going to collapse this somewhere, it might as well be ahead of the motor. Pictures and video below. Enjoy!

Here are some before and after pictures:

http://img.photobucket.com/albums/v401/blizazer/2008-07-19%20TA%20frame%20straightening/P7190151.jpg

http://img.photobucket.com/albums/v401/blizazer/2008-07-19%20TA%20frame%20straightening/P7190153.jpg

http://img.photobucket.com/albums/v401/blizazer/2008-07-19%20TA%20frame%20straightening/P7190167.jpg

And of course, the best part...video!

http://smg.photobucket.com/albums/v401/blizazer/2008-07-19%20TA%20frame%20straightening/?action=view&current=P7190165.flv

My favorite part of the quote above is "high speed pulls"...I really got a kick out of that.

Bryce

ClemSparks wrote: I'm glad everyone else has had good results trying to straighten frames with trees and chains. My one shot at it was unsucessfull.

That's two of us. Bent things that were straight, didn't straighten the bent things. Ripped some new holes in the chassis and such. Went so badly I decided to not try that any more.

A good logging chain is pricless!

for sheet metal repair? Along the side of the road or late night dirt track pit repair? Don't forget a pistol to stategicly place pulling holes ( I use a .357 Mag for 3/8 bolts ) Just double check where the slug is going.

Then double the chain around your sledghammer and do you best Hank Aaron impresion

I tried a 1 ton dually and a winch one time to straighten a 944 Turbo frame.....it didn't work. I ended up taking it to a bodyshop and paying 500.