Bent chassis

[critter]

Having trouble lining up front fenders ,hood etc, car is '37 aussie ute Ive discovered left hand rail is lower than right, and at the rear left is higher than right , the measurements are taken with the car sitting on stands under chassis, It appears to me the chassis may be twisted , Any advice or help would be appreciated.

[JSeery]

A frame shop should be able to get it closer to correct.

[critter]

Unfortunately frame shops are few and far between in Australia, My question is more directed to people who may have had a crack at it themselves, I have a porta power etc, I'm willing to have a go at it and also listen any who may have had a done so. All responses are and will be appreciated---------- thanks critter.

[51 MERC-CT]

You may not need a "frame" shop to do what you want, check auto body repair shops.
I have straightened several 'twisted and bent' frames over the years with nothing more than a floor jack and the most important thing, the ability to chain (anchor) the frame to the work floor.

[David J]

Originally Posted by critter

Having trouble lining up front fenders ,hood etc, car is '37 aussie ute Ive discovered left hand rail is lower than right, and at the rear left is higher than right , the measurements are taken with the car sitting on stands under chassis, It appears to me the chassis may be twisted , Any advice or help would be appreciated.

If you have a toy like mine in pic it's a real simple fix .
Assuming you do not it is still easy to fix .

Like already mentioned holding it down is the key .

RF and LR are high so you need to hold them down .
Holding down should be done AROUND THE MAIN FRAME RAILS at the front and rear crossmembers .
Once secured put a sturdy bottle jack [ or whatever ] UNDER THE MAIN FRAME RAILS directly under the crossmembers LF and RR .
If you have it secured well it will bend fairly easy and go in baby steps as you don't want to go too far .

When level check the X measurement to see if it has any " diamond " to it .

Feel free to PM me if you want as I have had that frame rack for over 25 years and have straightened MANY things on it .

DO NOT HEAT your frame .
Not needed anyway .

A copy of the frame dimensions would be good to have also .

Dave

[jimTN]

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Use a Ibeam some chains and you porta power. My experience is that most of the time you have to go past center when jacking for the frame to come back where you want it.

[David J]

To clarify - What you are describing sounds like crossmember- X issues .
NOT bent side rails .
Completely different problem .

[rotorwrench]

It really could be either bent rails or twist across the center. Modern frame straightening jigs would straighten it either way. Clamp or chain the high areas to the jig frame and start jacking on the low parts. The modern set ups allow for many more supports than the old K-frames did. A person can use a single I beam if only one rail is affected but it would take a double rail frame set up to work a complete chassis. It just depends on what a person has at hand that is strong enough to hold extreme pressures that it can take to do any given job.

[critter]

On closer inspection it seems only one rail is out of wack, Have tied it to the floor just under the seat Put a prop under the rear, And jacked up at the front, I have jacked progressively further until thr jack runs out of travel, After a bit of popping and groaning I have removed maybe 50% of it, i'm concerned about doing damage The rail has got a lot of spring in it ,Makes me wonder how it became bent, Should I keep pushing or try another method ??

[David J]

Make sure it is bending where you want it to .
Where is the " prop under the rear " ?

Should be at the rear crossmember or in front of the rear wheel where the frame is double thickness .

When being jacked around frame rails tend to bend at the weakest point .

Yes there is lotsa flex in frame rails .

[aussie merc]

sound like it was heavily pranged at some stage or its life and either sold off as a right off or / and home repaired sounds like your headed in the right direction but may need to find an older repairer that still has a MAYRACK aligner they just not used any more as it costs more to straighten a modern car than just pay it out just a hint look at those that repair light to medium trucks as they still have chassis

[rotorwrench]

The average U-shaped frame rail will have metal compression on the inside bend flange of the rail and stretch on the outside bend flange of the rail with some buckling of the vertical wall of the rail. How much deformation depends on how much bend deflection there is from true. Compression can be stretched with hammer work and stretch can be shrunk with heat and quench application. If the bend was concentrated in one spot then the one spot is all that needs to be worked if necessary. If the rail has a longer bow in it then the straightening gets a bit more complicated and will require several spaced bend points with the I-beam and jack or whatever is being used for the straightening process until the rail is closer to true. There will always be spring back so straightening force has to go beyond the true point till the rail is getting back to the desired shape. A person just has to apply force progressively in order to prevent going too far.

All this can cause more fatigue so it's not a bad idea to weld a reinforcement on the vertical wall in the area of the bend.

[johnboy34]

You said it's a ute, maybe it got twisted from hauling heavy somethings.

[big job]

As David J said holding it down is the key. No law says you can't dig a hole fill with
concrete with the dead man hook. I did, and it comes in handy

[rockfla]

The frame was bent on our 35 German Ford, we were lucky enough to have a 20' long 12" wide 1/4" thick Aluminum I-Beam that we were able to slide the length of the frame rail and chained it around the frame rail hanging the length of the frame.....Then we used a 20 ton bottle jack between the I-Beam and frame rail and jacked it were we needed!!!!!

[Frank Miller]

It sounds like this is a pretty much together car so you have some obstacles. I would begin by confirming that the frame is equal at all 4 points of the jack stands. From there you need to strt finding some reference points to determine exactly where the frame is out of alignment. I am not familiar with these frames so cannot be specific but in the end you're just trying to make a box square.
Maybe someone with a frame like yours off the car can give you a few measurements. Good luck.
Oh yeah, maybe take a shower. Lot's of good ideas develop there sometimes. We joke about that at work.

[big job]

String lines and a transit....

[rotorwrench]

Don't forget long strait edges. I also measure from the right front frame horn to the rear left end of the rail then check left to right & compare the readings. This will tell you if it's still square front to back. String lines will get a ball park figure but a person can measure the gaps with a straight edge. On frames with a natural bow built in are best checked on a frame table but where there is a will, there is always a way. Sometimes a person needs a known to be good frame or an original factory drawing to check all the dimensions depending on how complex the frame design is.

[David J]

A laser level is relatively cheap and gets rid of much guesswork .
That will also answer the IMPORTANT question about what is really bent .

Your first post sounds like the rails are out of wack with each other = crossmember - x member issue .
Left rail low in front and high in back is a classic example of this . In simple terms this issue is like king kong grabbing the frame rails on both sides and twisting them in opposite directions .
End result one side is low in front and high in back .

A single beam does not properly address this issue .
A single beam will indeed straighten a side rail .

Please don't make the mistake of bending stuff before you are sure where the problem is .

[critter]

I agree with your opinion on the cross member being twisted, i'm considering removing the rear jack stand to allow the frame to go beyond the correct point expecting to spring back to where it should be, I'll try this shortly, gotta get thru Christmas first. To everyone who's put forth an opinion thanks very much. have a great Christmas and new year, i'll no doubt be back then. CHEERS, critter