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When you tidy up the workshop....


Nitroholic

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no...they don;t hit. they are close...and I might ease it back a fraction to give room for tyre growth at speed. Turning is fine, as the wheels turn together, and stay well clear.

 

plenty of adjustment in the linkage I made, as its wound as far in as it goes. I could move the things about 10mm further apart if I need to.

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OK.....time to get serious with this.

 

Having done the rough mockup with the timber chassis, I could see how most of this would work and how the functional part of drive and steering cuold be arranged. There was only one bit I needed to sort out, and that was a driveshaft.

 

My original thoughts around a 6WD truck had used 4 wheels at the rear, not the front. I intended to remove both the drive cups from the diffs between the 2 rear axles and link it by simply drilling an 8mm hole down the centre of a bolt, and hooking it up with 2 grub screws. Simple....and as it uses the same principle as the stock drive cups to hold, I had no concerns over how it would hold up. But....there is a problem at the front. The first pair of wheels need to be on an angle for the kickup. This is a serious thing, as it allows the suspension to absorb the bumps as it hits lumps at speed. Were it vertical, the impact would be taken by the suspension pivots....and not the springs. So...the kickup had to be there for the first pair. The second pair don;t need to be angled...but it means the coupling CANNOT be parallel, and has to be at an angle both sides. That meant a driveshaft.....of some sort.

 

So.....

 

vyf8Gk1.jpg

 

A bolt was founf with an outside diameter roughly that of the end of a stock driveshaft. 2 3mm holes were drilled across it. To make sure they were as centred as I could get them, I had to file a couple of small flats to get an accurate centre punch divot so the drill didn't wander. It's not going to be 100% perfect....but its as close as I can get it. I then had to cut the bolt to length, and drill a further 2 holes in the ends ready to be tapped out to take an M4 grub screw. Effort one resulted in a snapped drill bit as the hole breached into the cross drilling. Could not remove the stuck drill tip....so that went in the bin. As I hate wastage......guess what is being used to provide the driveshaft pins..... yup....shank of a 3mm drill bit 🙂

 

JaNC9FQ.jpg

 

The ends were both drilled and tapped to take an M4 grub screew, and the pins chopped to size with the Dremel cutting disc. It's very hard steel......so forget hacksawing it! The bolt might need a little thinning where the thing exits the cups, but I won;t if I don;t have to. I reckon I have enough free motion to have it clear without rubbing. It will be fitted with a couple of o-rings either end to ensure no rattling, but the thing looks like it will server the required function. Both grubscrews have been locktited in place, and the ends made as neat as I could.

 

4C4EmF2.jpg

 

For size comparison....that is a short centre driveshaft from a Hyper 7 .....  My mini-driveshaft is around 30mm pin to pin. It will place the wheels about 10mm apart at the front, but also give me scope to adjut that if I feel I need to. Not by much....but...enough!

Now I can go ahead and make the chassis plate without worrying if the thing is going to be a bust....as there are no other issues I can see that will be a major problem.

 

Plan B for the driveshaft involved welding up an old driveshaft into a sleeve after cutting the heads off.  Might still make a 'B-shaft' later on to see if it works better. Will need to find a bolt....drill a hole down the bore..... and weld the ends up. Then clean it all up

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Plan B implemented anyway....just becuase I wanted to see if it worked well enough!

 

Took an old driveshaft, which actually was bent anyway, but not where it mattered for my purposes. Both ends were cut off...but at an angle....not flat.

Bit of filing was needed to get them the same ....but not a problem.

 

Then I found a bit of 8mm steel tube, just the right size for my needs. A piece was cut to length, then a slot cut out of one side.

Both bits of driveshaft were tapped into the sleeve, lined up on the slants, and clamped up to keep the pins parallel.

 

Then I welded the centre slantsthough the slot....and welded all the way up the slot. This should ensure the centre part of the shafts got welded together, and both shafts are then welded to the sleeve. I wanted a strong join.

 

Then I could grind back the excess, and leave basically an 8mm sleeve attached around the join and supporting it. I didn;t want to over-grind the weld...but I wanted to at least try and balance the thing a bit. Seems to have worked pretty well.

 

36hiIeU.jpg

 

Bit more fine fettling needed....but as the join was lined up on the pins....I got good weld all along. Going to get some wet and dry on it, and if I can hold it in the drill chuck...spin it up and get it shiny.

 

Have both options to fit and test run when its all done

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