Lawrie's chassis repair

[Alan461]

Latest development on Lawrie's ongoing winter service is that the rear outrigger is bent.
Having chopped out the offending section of the rear 2 1/4" tube that carries the trailing arm hangers we found that the remaining section is out of true by 20mm.
The new section has a sleeve inside to reinforce the weld and should follow the line of the original.
for this to be put together the long section that sits in the sill, the stringer (for want of a better description) had to be wedged downwards.





Now assembled it is clear something is quite wrong
the outrigger is bent forward making the stringer too long to fit as before.
Measurements from the other side confirm this.
The only thing I can think of to remediate this is maybe slice the upright box section and realign
the 2 1/4 tube then reinstate the upright when it's all true.
This will allow the trailing arm hangers to line up with the correct amount of toe in
Previously the trailing arm had been extended on one side by 20mm to achieve this.

[Kitchski]

I'm not totally understanding the issue here, or what exactly is bent. If the rear beam was bent somewhere between the trailing arm eyelets, you wouldn't be able to fit the trailing arm at all, as there is next to no give in the bushes. If you've sleeved the new section to the original tube, then it should align as before. What datum did you take in order to fit new eyelets to the outer mounts?

The side rail of the outrigger quite often does pop out of alignment, as there's a fair bit of tension in it caused by the welding when it was new, but it doesn't matter as long as you drag it back where it went before. In fact, even if you don't, it still won't make much difference as all that will happen is that the hole in the tub for the seatbelt bolt to pass through will need enlarging slightly

[Alan461]

The rear beam is bent forward by 20 mm at its outer end, (there's a photo of its mangled remains on Lawrie's previous thread)
The trailing arm hangers were roughly paralel to the beam albeit with oval bolt holes and bent upwards, because of this previous repairs consisted of an addition to the outer leg of the trailing arm to bring it back to line.
In its present condition the outer rail would have to be shortened by 20mm to pick up the edge of the beam.

[TurboTony]

This must have had a major 'event' to give such issues. Do you need to go further into the outrigger and suspension tower to correct the problem? Hopefully you can get the dimensions from the other side. Or is an exchange chassis a viable option financially?

Hope you get there - it is a nice looking car.

[Alan Whitaker]

Hi Alan
Thats why they extended the trailing arm, you will have to cut the shock mount to pull the lower arm into place, once you have the lower bar right it's going to be a bend or cut and re weld everything back into place.

Alan

Alan Is this measurement the same on both sides

Edited by Alan Whitaker on Saturday 7th February 21:27

[Alan461]

TurboTony said:

This must have had a major 'event' to give such issues. Do you need to go further into the outrigger and suspension tower to correct the problem? Hopefully you can get the dimensions from the other side. Or is an exchange chassis a viable option financially?

Hope you get there - it is a nice looking car.

Think Lawrie does too!
Can't get my head around what sort of prang would cause such a dent, body shows no sign of repair.

Alan Whitaker said:

Hi Alan
Thats why they extended the trailing arm, you will have to cut the shock mount to pull the lower arm into place, once you have the lower bar right it's going to be a bend or cut and re weld everything back into place.

Alan

That's the plan, less daunting now there looks like there's some resolution to it.
Good to hear someone confirm it's a sensible course of action too.

[Alan Whitaker]

It's a good plan, Is the top suspension pushed back, would have expected this if the bottom is forward by 20mm.
has the car had a secondhand chassis fitted in the past? or it might have been reversed over something and only bent the lower mounting bar.

Alan

[Alan461]

Alan Whitaker said:

Alan Is this measurement the same on both sides

Edited by Alan Whitaker on Saturday 7th February 21:27

I'll get Lawrie to measure it. Everything else checked out fine, just that beam at fault.

Edited by Alan461 on Saturday 7th February 22:05

[Alan461]

Alan Whitaker said:

It's a good plan, Is the top suspension pushed back, would have expected this if the bottom is forward by 20mm.
has the car had a secondhand chassis fitted in the past? or it might have been reversed over something and only bent the lower mounting bar.

Alan

I get what you are saying about the position of the shock mount. I'll find out soon enough.
Loads of history on the car but nothing about this. Caveat emptor!

[Kitchski]

This all seems really odd. That OSR wheel would need to take a hell of a clout to bend that!

Have you tried using whatever jig you've fashioned for NS on the OS? The measurements of tubing are one thing, but its only the position of the arm mounts that really matter there.

[Alan461]

Kitchski said:

This all seems really odd. That OSR wheel would need to take a hell of a clout to bend that!

Have you tried using whatever jig you've fashioned for NS on the OS? The measurements of tubing are one thing, but its only the position of the arm mounts that really matter there.

You're right, is odd, don't know how it would happen but it's 20mm shy of where it should be.
If it's not corrected then the hangers will need extending or the trailing arm will need modification.
No jig for it, we'll take the final set up from the geos as per previous thread.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Alan Whitaker]

Hi Alan.
My guess is that it reversed over something and just hit that corner.

Alan