LITTLE B' - David Brown bike engined mini tractor

Digging thru some more photos here, so we had reached the first full mechanical build stage, and the tractor was to be run for the first time on its new rear slicks...



slicks don't grip much on anything besides clean, firm surfaces, our driveway is none of that



However, with a bit of practice we learned how to make them hook it took a couple of near-backflips to work out that there was a particularly grippy piece of tarmac right beside the front door, (it was the bit where i weld usually so i always sweep it up afterwards - unintentional track prep!).  We also adjusted tyre pressures for grip and weight transfer gains, and learned the way the engine wanted to be driven.



so then he got a wheelie bar added! this is the mk1 exhaust, which was a straight thru pipe, it gave a lot of power high in the rev range, but it was just too loud lol, i wanted to be able to test out little things on it without p***ing off the neighbours, so in this pic it actually has tape over the exhaust exit, the tape actually killed a lot of power and made it nearly impossible to drive, so a mk2 exhaust was getting dreamt up at this stage.

One thing i noticed when painting was the weight of the front axle assembly, it seemed unnecessarily heavy.  At this stage i was already dreaming up how i was going make the mk2 version of the tractor, (the 'super-b', which has since became quite a different concept).  Anyways, as a test, i wanted to see how much weight i could take out of a sub assembly like the front axle by removing any unneeded weight, to give me ideas for how to make the mk2 better.  So the tractor got a new front axle, 40x40 box instead of 60x40, and with a thinner wall thickness.  the diagonals were changed to 16x16 box, although the angle between them was widened for strength, end plates made thinner, main pin and rear boss all machined to remove whatever i could, and the knuckle mount was redesigned.  The new axle weldment weighed 2.7kg, down from the 4kg weight of the original.  I hope some of what i learned in that exercise can be applied to the way i make the 'super-b' regardless of how different it will be to the 'little-b'

Yup, best way to learn is to do it, do it, and do it again. Gains experience for sure. I've built parts knowing I couldn't get them to work, but rather to just gain the experience of just doing it, even though the part wouldn't work. You learn way more that way.

Pretty high tech. Is that engine mount aluminum?

You are right PM, a lot of trial and error in this game, and if you are lucky the stuff that ends up in the scrap pile can be reused later - the old front axle ended up on the front of the thunder b race mower i did at the end of last year!

Thanks MM, but no lol its not an alloy mount, but the welds probably give that appearance, (i had been welding thin box just before and was kinda linking short bursts of weld so i didn't get too much heat and blow thru, then moved to the thick plate and forgot to change my technique haha) - i redid it later. The mount is mainly 3 and 4 mm steel plate a buddy did up for me on a CNC laser cutter. We have a Volkswagen show just outside Belfast at the start of April, the little b is going to go as an accompaniment to my housemates mk1 caddy pickup, (and hopefully hit the drag strip again too), so we will be pulling the wee tractor apart to prepare it, i'll be paying close attention to the mount then - seeing how the first one got so badly wrecked!

So by this stage i had sorted the driveline and chassis out, and it was finally time to do the bodywork.

The plan had always been to rivet body panels to the metal frame, and thats what we did, it took a fair bit of careful cutting, i'm pleased to say i was careful enough that i didn't scrap any panels.  the bodywork is 1.5mm THK alloy, which worked out well as it was easy to bend.  i had designed the body such that there were no double curvature elements to the panel work as i would be doing this with only an angle grinder, die grinder, drill, rivet gun and tinsnips.



in this pic the wheelie bar is set to let the front lift really high, that was just for sh1ts and giggles, it usually sits half that height, and for drag racing we found it should probably be set lower again.



The wee tractor then went for its first proper shakedown at the farm, it was great going down the motorway with the race tractor on the trailer, you just don't see that kinda stuff over here, it turned some heads.  I thrashed it like crazy - and it held up remarkably well, although breakages included, a broken light bezel, exhaust rubber, cracked exhaust u bend and a puncture.



post shakedown repairs and extra bodywork.

The bodywork looks great to be done with the tools that you had.

That old building in the second pic just reminds me of N.I. We have one like that on our property but it lost its second floor. I think there was a fire in it at some point.

BTW is that a Golf I see in that bottom pic?

Thanks man, its a VW caddy pickup truck which uses a mk1 golf front end and bodywork, wee tractors fit in the back just so

Oh nice! Bet that looks good!

wrenchlife drag team lol

Haha that wee thing looks so neat!