Group C replica Mazda 787B
Discussion
Thanks for the ideas Clive 
The lower tube is 2.5mm wall. I'm going to be putting in a small crossmember to tie the two rocker pivots together when I've decided on what I'm doing with the pedal box. Vertical loads are virtually nil at the rocker pivot, the coilover resisting the vertical component from the pullrod. Yeah I've been toying with what to do with the anti-roll setup. I was intending to pass the ARB radius arm trough from the front, through the vee inbetween the pullrod and coilover and drop down to the rocker. But I do like your idea if I can shift things around a bit and get it to work!
What are you thinking of using a pullrod setup on? They do look quite neat and can be made very compact. You have an extensively modified Ultima GTR don't you?
The lower tube is 2.5mm wall. I'm going to be putting in a small crossmember to tie the two rocker pivots together when I've decided on what I'm doing with the pedal box. Vertical loads are virtually nil at the rocker pivot, the coilover resisting the vertical component from the pullrod. Yeah I've been toying with what to do with the anti-roll setup. I was intending to pass the ARB radius arm trough from the front, through the vee inbetween the pullrod and coilover and drop down to the rocker. But I do like your idea if I can shift things around a bit and get it to work!What are you thinking of using a pullrod setup on? They do look quite neat and can be made very compact. You have an extensively modified Ultima GTR don't you?
As this is my first post here, I'd just like to say a general 'Hi!' to everyone.
Very interesting thread and some lovely work so far. Through work, I've done a few (IIRC 3) GrpC [body] re-creations / re-builds - don't underestimate how long that side will take. Also, don't necessarily write off the idea of a one off windscreen. There are companies out there who if you supply a master, will make a high temp mould from it and make you a screen. Once again IIRC, you'll be in for a bill of £1.5k-ish. OK, not cheap but as a proportion of the build cost...? Just a thought.
Watching with great interest,
S
Very interesting thread and some lovely work so far. Through work, I've done a few (IIRC 3) GrpC [body] re-creations / re-builds - don't underestimate how long that side will take. Also, don't necessarily write off the idea of a one off windscreen. There are companies out there who if you supply a master, will make a high temp mould from it and make you a screen. Once again IIRC, you'll be in for a bill of £1.5k-ish. OK, not cheap but as a proportion of the build cost...? Just a thought.
Watching with great interest,
S
RobBiggs said:
What are you thinking of using a pullrod setup on? They do look quite neat and can be made very compact. You have an extensively modified Ultima GTR don't you?
My chassis we started with blank sheet of paper like your doing, so has gone though a few updates along the way... My rear's inboard but the fronts still normal at present, would like to remove unsprung weight on them to. Always open to good ideas....Thanks. Two builds that stick in the mind both involved being given the cockpit section and being asked to recreate the rest (front and rear clamshells, doors, sills, wing etc). "OK" says I, "got any factory drawings?". "No" says he, "but I've got all these pictures". "Hmmmmm" said I, having taken a deep intake of breath.
Seriously, you need to pick an item of known length and try to scale from it. A far easier route would be to get some panels and 'cut and shut' them. Then do whatever styling and aero work is required and make new moulds. If you aren't going to make many, you can get away with quite thin (=cheaper) moulds but with a cross-braced wooden structure to keep everything nice and true.
Getting doors to fit nicely is a very long job so if you can get a cockpit section with doors to work with, you'll save a boat load of time.
Seriously, you need to pick an item of known length and try to scale from it. A far easier route would be to get some panels and 'cut and shut' them. Then do whatever styling and aero work is required and make new moulds. If you aren't going to make many, you can get away with quite thin (=cheaper) moulds but with a cross-braced wooden structure to keep everything nice and true.
Getting doors to fit nicely is a very long job so if you can get a cockpit section with doors to work with, you'll save a boat load of time.
I've been making more progress with the front suspension. I've built two wishbones, finished the upright/wishbone mounts and improved on the front suspension arrangement again
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One issue a had with machining the spherical bearing housings for the wishbones was the circlip groove. I do not have any internal grooving tools to hand so I simply machined the housings in two halves, TIG welded them together, and then machined the final bore. All seems ok so far as I've pressed the bearings in and out with no difficulty.
I was on the verge of getting my wheel centres machined up, but until I am 100% sure on the design of everything else in that area I've made a hub adaptor that positions a wheel with one of the original BBS centres fitted at the correct offset.
I had a trial fit of everything this weekend and everything is looking good. Picked up my new TIG welder too. Went for an AC/DC machine so I can fabricate my own fuel/oil tanks etc when the time comes. Next task is the newly designed pull-rod rockers. I've got the needle roller bearings and aluminium billets all ready to go. More updates coming soon....
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|http://thumbsnap.com/aAlc5P04[/url][url][url]One issue a had with machining the spherical bearing housings for the wishbones was the circlip groove. I do not have any internal grooving tools to hand so I simply machined the housings in two halves, TIG welded them together, and then machined the final bore. All seems ok so far as I've pressed the bearings in and out with no difficulty.
I was on the verge of getting my wheel centres machined up, but until I am 100% sure on the design of everything else in that area I've made a hub adaptor that positions a wheel with one of the original BBS centres fitted at the correct offset.
I had a trial fit of everything this weekend and everything is looking good. Picked up my new TIG welder too. Went for an AC/DC machine so I can fabricate my own fuel/oil tanks etc when the time comes. Next task is the newly designed pull-rod rockers. I've got the needle roller bearings and aluminium billets all ready to go. More updates coming soon....
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In order to get decent lower wishbomne lenghts I deliberatley lifted the front end of the spaceframe up a little to allow them to be mounted further inboard, underneath the tubes. When finished there will be a 5mm ally plate under this front section to tie the pivot point together, allow mounting of the pedal box and also serve as a skid plate. So the mount will be in double shear and introduce negligable bending moments to the tube they are mounted to.
The wishbones are fabricated from 22mm OD T45 tubing and are still more than adequate for any suspension loads they should encounter. One point to note is that loads are transfered through or very close to the pivot points meaning bending moments are very small. Wishbones on more conventional setups are often much heavier items since coilvers are mounted at 3/4 inches inboard from the lower ball joint, resulting in much larger bending moments.
The wishbones are fabricated from 22mm OD T45 tubing and are still more than adequate for any suspension loads they should encounter. One point to note is that loads are transfered through or very close to the pivot points meaning bending moments are very small. Wishbones on more conventional setups are often much heavier items since coilvers are mounted at 3/4 inches inboard from the lower ball joint, resulting in much larger bending moments.
RobBiggs said:
When finished there will be a 5mm ally plate under this front section to tie the pivot point together, allow mounting of the pedal box and also serve as a skid plate.
Ah! That's a bit more reassuring - my main worry was that it could have alarming consequences it the bolts locating these wishbones clipped a raised manhole cover or dropped kerb, or whatever.Gassing Station | Kit Cars | Top of Page | What's New | My Stuff