chassis support frame

[optima21]

for my herald I need to rebuild the chassis, so I thoought I'd be best to start off with a staight frame to build it on, built mainly from 50mm square box section and mig welded together.

so first of all I cut up some box section

then welded some nuts onto some square washers for the base of the legs

so that I could use adjustable feet on it

the main rails were then squared up so they were level

and then the cross rails were welded in place. there were just 2 50mm seams welded on each of the ends, one was welded and allowed to cool before the second seam was welded.

the legs were then welded on

and some diagonal braces were added

and the finished article......

...... well I wish it was but the main rails have bowed slightly due to the heat from the welds on then.

If I weld some beads in top and then grind the bead off, is it likely that the rails will straighten, its only 2 or 3mm but I'd prefer it to be straight. the other option would be to tack some pads on to on the rail at strategic points to measure from. what do you guys who know about these things think.

 

[mike 109444]

Are there not any tooling / location holes in the chassis that could be picked up on by your jig table ? I think the Hearald has a proper chassis (ladder?) as compared to the Capri but I would have thought that there should be some locating holes that you could create mounting posts/pillars for. That way you would avoid any thing on the rails from causing a see saw effect rather than laying flat. Pic below is underside of Capri type body and the diamond lines start at mounting points with dimensions.

 

[daedalusminos]

At the end of the day it doesn't really matter if your frame is square/twisted providing you allow for it when mounting your chassis and taking measurements.

You might have been better off welding those cross braces between the rails which should have minimised any bow.

Using liquid in a tube is a very accurate way to set levels over short and long distances.

 

[gaz1]

for after use a nice table there optima

 

[Slowcoach]

Not sure but 2mm might within original tolerances.

 

[optima21]

the herald has a separate chaissis, luckily the chassis drawing and dimension are in the factory workshop manual

http://www.optima21.org.uk/herald/herald_chassis.pdf

with hindsight it might have been better to bolt the frame together, although that would have taken me weeks at the rate I work

 

[Barlidge]

I made a build table for my haynes build out of box section, had similar bowing issues with the weld but luckily the welds were on the inside faces so the cross members pulled it back straight.

 

[Slowcoach]

Are you repairing what you have or building a complete new one.

 

[optima21]

its being repaired, but there will be plenty of fresh metal going into it, like a set of new coutriggers and side rails for the chassis

 

[Slowcoach]

Have you spaced the rails in your jig to accommodate the waisted chassis rails, coz it looks to me like only the outriggers will clamp on to the jig.

 

[optima21]

my way of thinking is to mount the chassis on the shorter lengths of box section used as cross member so that it then clear the longer lengths which can be moved backwards and forwards as necessary. the longer loose crossmembers are slightly longer than the distance between the side rails of the chassis

 

[daedalusminos]

That's quite a structure you're building, but it is only a jig and therefore only needs to be able to support the weight of the parts with out flexing. The heaviest part will be the main chassis backbone, after that the outriggers and side-rails are relatively light and the jig doesn't need so much strength in these areas.

The workshop manual sets an imaginary datum plane above almost all of the mounting points, obviously this plane can be transposed anywhere with adjustments to dimensions but it might be a good idea to rebuild the chassis upside down, after all the the reference points to the outriggers.side rail are the upper (body side) surfaces. Also the top surfaces of the outriggers are flat.

I'd rebuild the chassis upside down, and build your jig with 'outriggers' to which you can attach bolts upright (the diameter to match the outrigger/siderail mounting holes), have these bolts in enlarged holes so you can adjust the position. A couple of lock nuts and a washer can be used to adjust the seating height. This way you can fine tune the jig after welding. It's then just a matter of mounting the backbone and laying the outriggers/siderails in place and welding.

This thread describes the liquid in tube spirit level...

https://www.mig-welding.co.uk/forum...lly-accurate-square.82909/page-2#post-1180862

 

[Wildefalcon]

To straighten, heat the outside of the bend to cherry hot, and encourage the bend to decrease. I used a jack. Heavy wall box and clamps can also work.

Repeat until bored.

Build the chassis back up the way you thought it through, in your head. but once the ladder is sound you might wish to rotate the chassis, to get at the underneath, for tidier welding.

 

[Slowcoach]

my way of thinking is to mount the chassis on the shorter lengths of box section used as cross member so that it then clear the longer lengths which can be moved backwards and forwards as necessary. the longer loose crossmembers are slightly longer than the distance between the side rails of the chassis

View attachment 175981

Looks like you have it sorted, I mistakenly thought you were just going with the original pictures.

 

[optima21]

I managed to get it straightened today, using a few beads using my TIG welder and a wet rag to shrink the weld

and this is about as straight as it is going to be

 

[iwoo]

Have you got a copy of the proper Triumph workshop manual with all the measurements on? I have one for the Vitesse mega usefull.

 

[octo0072000]

Looks good but fasten the argen bottle to something before you drop it and scrap your gauges

 

[optima21]

Have you got a copy of the proper Triumph workshop manual with all the measurements on? I have one for the Vitesse mega usefull.

yeah Ive got the workshop manual, makes it easier to have some proper dimensions to work with.

 

[Wallace]

Are you going to add some retractable wheels? Might be worth changing the plastic leveling feet to something stronger that doesn't absorb molten blobs of steel or fracture and put the frame out of level as the weight increases. I made a dolly for moving and rolling a car here if any of the info is any use to you.

 

[nickk]

Was a herald made to accuracy’s of 2 mm?
No offence though always liked them & vitesses .BTW,hows the Clarke tent surviving the sparks?