Anyone build a chassis roller / frame from scratch?

This came up in another thread, but I reckoned it might be of interest as quite a few folks on here seem to be interested in MIG welding for car restoration.

What I was thinking of fabbing as my first project is a "spit" device, possibly with a supporting frame or jig, (malcolms idea!), that would allow you to mount a stripped out bodyshell to it and then rotate the bodyshell through 360 on its long axis.

There are commercial products out there already like the CJAutos Chassis tilter, but at that kind of money it HAS to be cheaper to build something yourself from scratch. It doesn't need to have all the bells and whistles, but the basic spit idea would be perfect for working on the underside of the car. Being able to weld standing up or looking down on the work should improve the quality of the welds too as you will be far more comfortable.

So has anyone fabbed anything like this before? Got any pictures / tips / tricks you would care to share?

I can just see something like this being time well spent at the start of a resto, and hopefully if built with some adjustability in the design could be re-used for subsequent resto / bodywork.

So who is going to get the ball rolling then?

Cheers,

Chris

My jig is kind of specialised. The next Renault project has lost the connection between the sills and front longerons so the front of the car is resting on the torsion bars.



I'm building a jig from some dimensions in the factory workshop manual and using a spare chassis which still has it's shape to provide the dimensions that the factory didn't. Reckon I'm within 0.2mm tolerance so far which is pleasing. The jig will pick up on the front and rear suspension mountings as well as the floor, the front crossmember and the bumper mountings at the back.

I've got a pair of A frames to roll the chassis. There is a scaffold pole welded end on to a plate that attaches to the jig, then a piece of tube with the inside diameter matching the outside diameter of the scaffold (2 inches) attached tot the A frame to act as a bearing. Haven't sorted out any means of organising the location of the chassis on the rollers yet but I'll probably weld a nut to the outer of the two tubes that form the bearing and screw a bolt onto the inner tube. Should work so long as I get the centre of rotation/gravity right.

I'm only going to this effort of a jig because I know I've already lost alignment of the suspension mountings. If I were replacing sills on a Golf I'd be inclined to weld braces low down on the door gap. If I were to attach rollers to the front and rear to get the thing into a sensible position then diagonal strengtheners across the doors would be a good plan.

Thanks for the info and suggestions on the temporary door braces for the golf.

Nice pics of your jig - looks like very neat work too!

Probably getting a bit ahead of myself here, but if all goes well on the golf, my next project will probably be an early Mk1 MX-5. Love these cars, especially the Mazda approved BBR turbo conversions. Rarity means I will probably be looking at one that needs work to be affordable.

These always seem to need work done on the area in front of the rear wheels low down on the sill. The jig idea appeals for this type of work as I'm not sure how easy it will be to keep the body straight as its got no roof!!!

I might try and do some CAD drawings up and have a fiddle to see what I can come up with design wise for a spit and frame setup.

One think I have always wondered with these roll over type frames is how do you find the centre of gravity for the roll over axis - is it purely trial and error?

Chris

I've nearly finished the chassis jig (a few tacks need seam welding, and I'm quite proud of it so want to paint it yellow) but here's a photo of it's first flight:



The centre of gravity was fairly easy to guess for me - it's easy to work out the centre of gravity of both the chassis and the jig, and if the weights are known to figure out the pivot point. I guessed the weights but it seems pretty close. There is no form of location on the A frames to hold the chassis at the right angle, but there is a surprising amount of friction on the bearings that holds the chassis quite solidly at any angle.

I noticed the A frames in your link had their own lifting arrangement. With mine I need an engine crane to lift the chassis to the right height to plug in the A frames. Mine is a bit high off the ground (I was given the A frames) but they are a good height to take a body attached to the chassis. I can always shorten them if it's a pain.

I did make a couple of mistakes. The biggest was using C section channel for the frame which has no torsional stiffness at all. I based it on a sketch in the Renault manual which used C section, but of course their jig is bolted to the floor! I'll have to check my torsional alignment occasionally by levelling up the front of the jig then making sure the back is level too. Box section tube might have been a better idea, if a pain for bolting bits on.

Incidentally, here's another post about chassis rollers using A frames http://www.mig-welding.co.uk/forum/showthread.php?t=560 (one that bolts to the bumper mountings). I was all for doing something like that originally, then realised that I would be removing 2 sides of the rear chassis members. Much the same concerns for sills on an open car I guess.

So Malc. You gonna build up these frames then offer em out at good prices to forum members?
Alex

I'd no idea there would already be a demand for Renault 4 chassis jigs. The brainwashing book suggested it might take a little longer to have you all driving around in the very fine little Renaults.

Nice link and pics malcolm .

Just a question on the tubing used for the spindle and the "bearing sleeve" trype tubing used on these spit type chassis rigs? I guess scaffolding pole would be good for one of the parts, but is it easy to find a diameter of mild steel tubing that the scaffolding pole will fit snugly inside / around.

I know from buying rectangular cross section steel tubing that several sizes are produced that enable you to make up assemblies where one steel tube type fits snugly inside another. Is this the same for circular cross section steel tubing?

Sorry if the above seems like a daft question, but I'm a bit new to all of this

Thanks,

Chris

I suspect circular section does come in slot together sizes too. Probably worth asking at a steel supplier for options.

Mine came with the A frames and I guess was made professionally as a body roller at some point, although I don't know by whom. The pivots on it are really meaty and slot together perfectly (ID 38.0mm OD 56.8mm and ID 56.9mm OD 76.8mm). A good tight fit seems handy to prevent the chassis from rattling around.

All that bad boy needs is 4 pneumatic wheels and a hot coat of paint. Very nice.

It's had a coat of paint now and looks magnificent. I found a pot of blue hammerite in one of the barns which saved me the cost of spending money. Took a whole day to paint!



Had to spend money on nuts and bolts though - 60 of them in there! And worse - stopped off on the way home and bought a £120 socket set to put it all together as the old one had become annoying.

Reckon I'll get the money back by selling it to the Tate Modern when I've finished with it.

Malcolm - that looks really slick - a real pro job.

I can't wait to get all the gear together to start on my own roller - soon, soon!

Chris

Guys, if you have a look on www.62ford.com you will find links to enough information to build a chassis roller, or Auto Rotisserie in US english.

My homemade chassis tilter

Pictures aren't great but there's an insight into my chassis tilter here:

http://flickr.com/photos/citroencrazy/155414138/in/set-72157594147592311/

I'm very glad I built it, without one I would have given up before I'd finshed welding a floor back into my aging Citroen

Andrew

That's clever. I like the high lift jack and chain hoist. Should make it much quicker and more user friendly to use. I've been rust proofing an elderly Renault on the ground today as my roller would take a day to attach.

Can't say I've seen a Citroen GSA about for a long time.

I Restored/Rebuilt a 16 VALVE Triumph TR7 quite rare car' only hundred or so built a nice car in it's day, I built a chassis tilter for the project that I got from street machine magazine I still have the plans for it some where, so simple ,main components are full size Builders trestle, bit of chopping and welding that's it, they worked a treat, they were quite posh back then, most people were still rolling cars on old mattresses, I will dig them out and post them up on here, might be handy/useful on the forum.

I made this a few years ago to work at Mk1 Escorts.




More details are here :-

The Spit

All the best, Neil.

Neil Fletcher Racing

Quite a lot of us have them on the Caddy forum:




Rather like the twin engine stand one - gets alot of the hard bit done for u!



Mine