HJ47 Bent/Twisted Frame Unsure... (1 Viewer)

[Ozzy75]

Hi all,

Currently stripping my HJ47 Ute back to it's frame and am checking it over for squareness. Pretty new to this and unfortunately the second frame I had which I was hoping to use has far too much internal rust to consider it so I'm trying to seek some advice on how bad the frame I have is in the grand scheme of things...

I've attached some photo's below showing the other frame I have which measures square and correct but too rusted to use vs my frame... You'll notice it has lost its S like bend in it from the tray mount forward to the body mount, the body mount also sits aiming slightly upwards vs the other side I'm assuming at some stage in it's life its take a hit from a rock or something and pushed the cab mount up as it looks ever so slightly pinched inwards in the corner...

The frame also looks more straight...

I've then attached another image showing green and yellow lines of where I've taken diagonal measurements and depending on where from it's usually anywhere from 5-20mm max out... now what I'm wondering is this quite a lot? Does the frame need to truly be stripped back then laid on flat ground and measurements retaken?

It's on fairly uneven ground currently, the rear passenger side leaf spring is twisted and has a snapped U bolt so not retaining the spring correctly as when I brought the ute it had a blown tyre wrapped around the axel and what looked like fencing wire wrapped around the front passenger side...

The cab didn't look to have any obvious big damage possibly just farmers fence or something and then driven on a flat home sort of situation, I've got no idea to be honest the ute was a barn purchase with no history or any info

 

[Ozzy75]

 

[45Dougal]

Unless the chassis has got a significant asymetric load on it, then it should be pretty square regardless of the terrain. Lift it onto axle stands if you're concerned that the axle is causing it to twist.

The only thing that really matters is that the wheels are all aligned, so if the chassis has a slight bend in the middle then I wouldn't worry, so long as the spring mounts are in the right place.

Worth noting that the reference points that you've chosen may not actually be symmetrical.

The leaf spring mounting points are symmetrical so they are a good reference to measure between.

I'd repeat your cross measurements between the front 4 spring mounts. Then the rear 4.
Then the larger crosses between the front and rear mounts.

It looks like your measurements are upto around 2000mm, so 20mm is only 1% which on a truck like this is fairly manageable I'd say. A bottle jack and a fence post should square it up.

If the second chassis is loose, maybe you could flip it upside down onto the bent one for a comparison of the top mounts?

 

[Ozzy75]

Unless the chassis has got a significant asymetric load on it, then it should be pretty square regardless of the terrain. Lift it onto axle stands if you're concerned that the axle is causing it to twist.

The only thing that really matters is that the wheels are all aligned, so if the chassis has a slight bend in the middle then I wouldn't worry, so long as the spring mounts are in the right place.

Worth noting that the reference points that you've chosen may not actually be symmetrical.

The leaf spring mounting points are symmetrical so they are a good reference to measure between.

I'd repeat your cross measurements between the front 4 spring mounts. Then the rear 4.
Then the larger crosses between the front and rear mounts.

It looks like your measurements are upto around 2000mm, so 20mm is only 1% which on a truck like this is fairly manageable I'd say. A bottle jack and a fence post should square it up.

If the second chassis is loose, maybe you could flip it upside down onto the bent one for a comparison of the top mounts?

Good idea with the second chassis have been trying to use that as reference as much as possible for measurements...

Yeah was wondering if the rivets are off and some of the mounts which seems they may be from factory..

Any chance you could explain where the spring mounts are ? I'm guessing hidden whilst the axels are attached? And would it best to measure from front spring mount to rear to check for squareness ? Or are they spaced enough to do smaller diagonals over rear then front ?

 

[45Dougal]

I mean between the brackets on the bottom of the frame that hold each end of the leaf springs.

Measure across at each pair of springs as shown below. Then try a big cross from end to end.

You can also use a laser (if you have one) to shine down the length. Align with brackets on one rear side, and then measure the distance from the laser to the front brackets.

 

[Malleus]

It might be helpful to compare your measurements to the frame drawings. I agree with @45Dougal the frame shouldn't be affected by the flatness of the terrain. I'd also consult the drawings to ensure that the datums you're using are actually supposed to be in the same place.

Bottom line is that the frame doesn't need to to be straight, it just needs to meet the body and axles.

 

[Ozzy75]

I mean between the brackets on the bottom of the frame that hold each end of the leaf springs.

Measure across at each pair of springs as shown below. Then try a big cross from end to end.

You can also use a laser (if you have one) to shine down the length. Align with brackets on one rear side, and then measure the distance from the laser to the front brackets.

View attachment 3413213

@45Dougal Ahhh right makes more sense now I guess if those mount's are square and correct thing should drive right, regardless of the fame being out ? unfortunately no laser at this point could only afford a decent dewalt impact wrench

appreciate the feedback and advice, my first proper full rebuild so a lot to be learned along the way!

 

[Ozzy75]

It might be helpful to compare your measurements to the frame drawings. I agree with @45Dougal the frame shouldn't be affected by the flatness of the terrain. I'd also consult the drawings to ensure that the datums you're using are actually supposed to be in the same place.

Bottom line is that the frame doesn't need to to be straight, it just needs to meet the body and axles.

@Malleus I did get a few frame drawings and the width matches along the frame however cross sections on the drawing I had to don't seem to match my point's but my body mounts do look out of wack and there for my diagonals on the top section of the frame are off even just measuring off just the frame like in the photo above their still off...

But like 45Dougal has mentioned I'll go measure the spring hangers tomorrow and hopefully the align correctly and square... It's good to know that the frame can be a bit off as long as their right to the axels I should be good!

 

[Malleus]

Laser levels are ridiculously cheap now:

 

[45Dougal]

Laser levels are ridiculously cheap now:
View attachment 3413428

Definitely. Get one that you can lock to the body as well as hanging free - maybe all do that??.
Be prepared to work at dusk if you're outside in the Australian sun! These things aren't too bright.