Frame straightening

[steve from staten island]

when I broke into the trade we would get fired if we used bondo glazing putties we metal finished and used lead

The guy who did the bodywork on my car used lead. He leaded the quarters and was really something to watch

 

[Cornpatch MO]

Thanks for the thread. Until this day, I did not know that unit bodies could be straightened..............................MO

 

[Bladecutter]

The guy who did the bodywork on my car used lead. He leaded the quarters and was really something to watch

Lead is a pain, hard to work, time consuming, HEAVY, non structural & will check over time just like mudd. I'll put my epoxy/glass fill against it anytime. 18 ton load on a puck of it in a hydraulic press without shattering, fracturing. The press leaked & couldn't get past 18 tons.

 

[bm02tj]

Half the battle with frame straightening is the tec being able the read the damage
30 Years ago I bought a 72 GMC short box that did not look right but price was to good to pass up
Took to a friend that did straightening on highway trucks on down
after poking around the truck he told me the frame was straightened improperly
well undoing what the last guy did on the final twist the box was 1/2 way up the back window
when he released the pressure it drop down perfect

 

[Bladecutter]

Takes knowing the threshold of flex & moving just past it.

 

[mopar 3 B]

Lead is a pain, hard to work, time consuming, HEAVY, non structural & will check over time just like mudd. I'll put my epoxy/glass fill against it anytime. 18 ton load on a puck of it in a hydraulic press without shattering, fracturing. The press leaked & couldn't get past 18 tons.

What you using for epoxy/glass fill and what you doing to prevent poop out?

 

[WileE]

Thanks for the thread. Until this day, I did not know that unit bodies could be straightened..............................MO

Sure. Don't forget he unibody cars we repaired going back to the 60's Mopars, some Ford's, etc. Then, the structures were mild steel. We could heat & pull. It's not the same with high-strength and ultra high strength steel in modern cars.

 

[Bladecutter]

What you using for epoxy/glass fill and what you doing to prevent poop out?

Not sure what You mean by poop-out.
I buy from a glass house in San Diego called Aero Marine Products.
Their 300-21 epoxy resin/catalyst. Res is 300, catalyst is 21.
2 parts res to 1 part catalyst. Ratio is critical to keep close to exact.

1/32nd milled fibres...uniform ground glass.

Cab-O-Sil, fumed silica. A stiffener plus gives structural integrity along with the milled fibre.

By volume, if I mix 4 oz. of 300-21, I add 4 oz. milled fibre, & 4 oz of Cab. The Cab stiffens the mix & in that ratio the mix is stiff enough to spread upside down & it will stay exactly where You put it.

Epoxy resin is 6 times as strong as polyester resin, ABSOLUTELY water proof & minimal shrinkage. Polyester resin has a shrink rate of 10% of its volume. Epoxy resin does not get near as hot as polyester resin in the kick process so the danger of resin boiling at center is not as critical. However it should not be spread on in applications more than a 1/4" thick per spread to avoid any resin boiling. But You can spread another app right behind 1st spread after 1st one kicks & cools as long as 1st coat does not become contaminated by airborne particulates.....no intermediate sanding required. If it does get contaminate on it, wash with acetone well & then apply second coat.
The drawback, You must allow a good cure window before working. 24 hours is MINIMUM. Have to be organized enough to rotate the work, so while You're sanding a spread in one area, another is curing in another area.

Kick & cool time is about an hour in 80 degree temps, which allows a very generous window for spreading....very helpful if one is doing expansive skim coats.
1st., spread very thin with pressure over entire area for full coverage. Then roll back pressure to apply in desired thickness. It has a much different feel than spreading bondoe(which is just poly resin & talc). Even with a stiff mix, the stuff will spread thin under a lot of pressure. You have to develop a feel for how to roll it on. Primary thin pressured spread is to insure a good bond to substrate.

Aero Marine has all kinds of supply & instructional videos on YouTube.
Richard is very Friendly & helpful to questions via email or phone.

 

[mopar 3 B]

Poop
Debond
Brake loose

 

[Bladecutter]

Poop
Debond
Brake loose

Uh Uh!! Raw metal grind with 80. If an already etched & epoxy sealed surface, cut the sealer open with 100-120.