Project "Payback" - Lateral-g Forums

Vegas69 · #1 06-18-2011, 07:47 PM

With anticipation of the event at California speedway next month, I started my pre race inspection and I'm doing a rear brake conversion. It didn't take me long to find a problem.

My frame is cracked on both sides.

I'm really not sure if it's from the SCCA event or the drag race last month. I'm leaning towards the drag racing but it broke at the triangulated mounts which makes me wonder.

My question to chassis and fabrication guys on the forum. Can I have it welded up(Reinforcing) and what type of welding? I still want to make the race in California next month. What would you do?

coolwelder62 · #2 06-18-2011, 08:14 PM

I would clean the frame rail to bare metal passed the OEM Galz.coating.Use a small grinder and bevel the crack to the inside of the frame rail.I would use a tig welder to control the heat in the weld zone.Then metal finish the weld smooth.Trying not to remove any of the frame rail material.Fab a small diamond shaped gusset(3in.tall x4.5 long) for the outside of the frame.Then I fab surport gusset the shape of the frame from the lower bracket to upper on both sides of the the frame.This should spread out the load from the upper link's thur the side of the iner frame back to the shock cross tube.Todd good luck.If you were closer I could help you out.

Scott M.

**GregWeld** · #3 06-18-2011, 08:16 PM

Clean it - grind it out a bit so it's clean - weld it up - then FISH PLATE it.... I'd tie into the crossmember - which is the origin of the crack. That crossmember was welded with too much heat and caused the metal to become brittle right next to the weld area. Poor welding - plain and simple.

**GregWeld** · #4 06-18-2011, 08:28 PM

BTW --- Welcome to the world of high horsepower and big sticky tires... on 42 year old metal. The too high of heat caused "carbonization" of the base metal... in other words - it became brittle.....

It's really not uncommon nor is it a "big deal" now that you've discovered it. Just make sure you go to a REAL chassis shop that knows how to weld stuff correctly. Lots of people can stick two pieces of metal together -- but that ain't all there is to welding.

ironworks · #5 06-19-2011, 04:57 PM

Quote:

Originally Posted by GregWeld

Clean it - grind it out a bit so it's clean - weld it up - then FISH PLATE it.... I'd tie into the crossmember - which is the origin of the crack. That crossmember was welded with too much heat and caused the metal to become brittle right next to the weld area. Poor welding - plain and simple.

Don't ask how I know. But we worked on a car

with the same issue, only worse. The problem is the brackets are alot thicker then the stock frame rail material. And when you weld it in it needs more heat on the thicker material to make it actually penetrate the thicker stuff. Those parts are actually designed to be bolted in and one of my customers who has an engineering masters degree and a degree in welding inspection looked at the car here at the shop and said it might not have broken had we just bolted it in. CRAZY?? So on said car we just plated the outside frame rails with 1/8inch plate to spread the load over more of the rail.

Let me see if I have some pictures

g356gear · #6 06-18-2011, 08:20 PM

Wow, with that much torque, and that much tire, there must have been a ton of twist on those rear rails to cause a stress crack. It almost looks like the welding in of the 4-link may have weakened the frame rail and made it brittle along the weld edge.
If it were me, I would think the best way to repair would be to get the cars weight supported so that the cracks close up and then re-weld the crack. I would then probably section out the outside of the frame rail and add steel to the inside of the channel to re-inforce the rail. After that, close up the outside of the rail and maybe add another plate of steel to match the rail profile and give it some more thickness.
Without removing the 4-link, the access is pretty limited. Grafting in heavier rear frame rails might be in order during the off season.

skatinjay27 · #7 06-18-2011, 08:32 PM

just get some beefed up art Morrison frame rails in there!!!!1

what greg and mock said above will be good to go.

no way it was solely the drag racing... seeing your 60s you didnt hook hard enough to cause that instantaneously, im sure its been a slow process. by the location of the crack you can deffinatly tell it was weaken due to the bracket being welded in...

as far as having someone local do it, Im pretty sure russel still does work at his home shop and for your anal azz he's the only person local i can think of that will work for you. call curtis i think he has his contact info.

BBC71Nova · #8 06-18-2011, 09:42 PM

Wow. Now you've gone and done it

.

for those pre-race inspections. I'm guessing those don't happen enough for many people. This is a good reminder for everyone.

Vegas69 · #9 06-18-2011, 10:36 PM

I was actually kind of proud of myself.

I've always kept a close eye on the rear frame rails. They are original and in very good shape but I was never impressed with the welding that holds the cradle in the car. It's definitely happened within the last 2 events. I get on a creeper and go from nose to tail with a flash light on a regular basis.

John is absolutely correct. It's very important to stay on top of these cars, especially when you run them at the limit like I do. 6000 miles and over 20 races. I'm not surprised but glad I found it before my trip to CA next month.

Thanks for the advice guys. Maybe I'll swing by Ironworks on the way to the event. I wanted to drive the car, but I may end up just trailering to Ironworks and having them fix me up and on my way. If I can't find someone local I trust, which is not likely at this point. Greg, I was thinking the same thing. Tie it into the cradle.

coolwelder62 · #10 06-18-2011, 10:42 PM

Quote:

Originally Posted by Vegas69

I was actually kind of proud of myself.

I've always kept a close eye on the rear frame rails. They are original and in very good shape but I was never impressed with the welding that holds the cradle in the car. It's definitely happened within the last 2 events. I get on a creeper and go from nose to tail with a flash light on a regular basis.

John is absolutely correct. It's very important to stay on top of these cars, especially when you run them at the limit like I do. 6000 miles and over 20 races. I'm not surprised but glad I found it before my trip to CA next month.

Thanks for the advice guys. Maybe I'll swing by Ironworks on the way to the event. I wanted to drive the car, but I may end up just trailering to Ironworks and having them fix me up and on my way. If I can't find someone local I trust, which is not likely at this point. Greg, I was thinking the same thing. Tie it into the cradle.

That sounds like the best way to handle it Todd.the crew at ironwork's can fix correctly.