29 replies to this topic

[miniracer115]

Is there a trick to getting the shell so it rotates through 180deg easily. I have one of the rollover jigs that mounts onto the bulkhead and rear damper / parcel shelf. I just can’t get it to rotate without having to use a lot of muscle to turn it and stop it spinning out of control when going over. I’ve seen the videos of this jig rotating and can be done with one hand. What am I doing wrong. Thanks

[skoughi]

The pipe that runs from the car to the frames at each end of the car is to high in relation the the mass of the body, it needs to be closer to the floor. I knocked up a rollover jig for my clubman made from scranned scaffold pipes. I had a pipe running right through the car that was fixed to a crossbar that sat on top of the front crossmember and at the rear there was a crossbar that was bolted to the top damper mounts. However this scaffold pipe at the front was right inline with the slam panel so couldn't continue onto the frame. I took a shorter pipe and fixed it directly underneath the main pipe, this sneaked under the slam panel and onto the frame. I had the same arrangement at the rear to keep everything level. Once mounted on the frame it proved very easy to turn. So going by what I did if you make the pipes going out to the frames about the same height as the front crossmember or slightly lower in relation to the floor line so the same front and rear then the body should turn easily once mounted on the frames. 

[skoughi]

Sorry I've read your post again and it seems to suggest that the bodyshell wants to turn too easily and you have to try and control it. That would then suggest that the pipe that goes to the frames is too low regarding the mass of the shell? You could mount two short pipes on top of the pipes already there to raise the point that the shell rotates and see if that makes things easier? 

[miniracer115]

No it’s really hard to turn. I practically have to lift the car to turn it upside down and then when trying to rotate it back again have to hold the full weight to stop it spinning out of control.

[miniracer115]

Will post some pictures tomorrow of set up.

[skoughi]

Ahh right, so there's too much mass of the shell below the pipe. As I said then on my first post you need to effectively lower the point at which the shell rotates around. Get another two short lengths of pipe and safely fix them to the underside of the existing pipes and then use these to go into the frames at each end. This will put more mass of the shell above the point that it rotates around.

[miniracer115]

Thanks, so if I try and lower the car and effectively raise the central rotation. Will give it a try.

[miniracer115]

I mean other way around!

[skoughi]

If you have a search on the projects forum for "My Fixerupper" then have a trawl through the photos you'll find ones with the Clubman shell mounted in the spit. Even though it's a Clubman shell you might be able to get an idea as to what height to have the pipes at in regard to achieving a more balanced mount.

[whistler]

I've just fitted a new rollover jig from rolloverjigs.com and mine's the same. The pivot holes are far too high so looking to relocate them and turn the end frame upside down so as to lower the centre of gravity. Mine's the single post type not the A frame ends type.

Attached Files

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Edited by whistler, 26 May 2020 - 11:43 AM.

[miniracer115]

Mines from them but the a frame type. I’ve just realised I’ve fitted the end frames upside down compared to which way they are in other images on the net. Going to change it and use the same bolt hole combination they use. Fingers crossed it’s this simple.

[Cooper Mac]

The centre of mass of the car is too low here:

 

 

The horizontal frame needs to be moved further up the mounting holes (circled in red) to bring the centre of mass as close to the pivot axis (circled in blue). This will then make the body easier and a lot safer to turn! I suppose it is really trial and error to get it right, and it may need to be adjusted depending on how much material is removed and added!

[DomCr250]

I made the scaffold pole through the speedo hole and across the rear shock mounts.  Yes the mass of the car is slightly wrong.

 

Solved it by welding an old 1/2" socket to the end of the scaffold pole, then stick a ratchet or pry bar in it, put a 4 foot bit of pipe on that and you can easily swing it about.

 

If you dont control it well it will start swinging back and forth - I used scaffold joining clamps as rotation bearings on top of the A frame supports, this meant you can slacken them off enough to rotate the shell but not get too much movement in it.

 

Always thought the rolloverjigs.com looked like hard work, badly designed and expensive too - mine cost just over a tenner, and thats was for the 4 scaffold joiners from a local sacffold company, everything else was just scrap I had lying about.

[whistler]

The centre of mass of the car is too low here:

 

 

The horizontal frame needs to be moved further up the mounting holes (circled in red) to bring the centre of mass as close to the pivot axis (circled in blue). This will then make the body easier and a lot safer to turn! I suppose it is really trial and error to get it right, and it may need to be adjusted depending on how much material is removed and added!

I have drilled a much lower pivot pin hole to move the CoG to be level with the crossmember. Rotates much easier now. Just fiddling with the vertical brackets now. Do all mini shells tilt at 30 degrees when untethered from the locking pin? I assumed the shell would be fairly level (sideways) as there doesn't seem to be any more metalwork on the one side than thte other, unless it's because I have a lot of tin worm bits fallen off!

[Homersimpson]

I made the scaffold pole through the speedo hole and across the rear shock mounts.  Yes the mass of the car is slightly wrong.

 

Solved it by welding an old 1/2" socket to the end of the scaffold pole, then stick a ratchet or pry bar in it, put a 4 foot bit of pipe on that and you can easily swing it about.

 

If you dont control it well it will start swinging back and forth - I used scaffold joining clamps as rotation bearings on top of the A frame supports, this meant you can slacken them off enough to rotate the shell but not get too much movement in it.

 

Always thought the rolloverjigs.com looked like hard work, badly designed and expensive too - mine cost just over a tenner, and thats was for the 4 scaffold joiners from a local sacffold company, everything else was just scrap I had lying about.

I have one for a MK2 jag and i've done two cars on it, they are fine if you know how to use them and their loading tool works really well. 

 

The problem with the one photoed above is that its not balanced correctly.  If you look at the photos on their website the front beam is the other way up.