Rebecca Taylor
www.brickshelf.com/cgi-bin/gallery.cgi?m=techgrl

Modifications to Technic JCB (8862)
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I think this was probably one of the best Technic sets ever.
I have however made several changes to the original model:

1)
Widened the front track by two bumps each side and the rear track by one bump each side.  I felt that the instructions made the vehicle too
narrow.

2)
Beam axle suspension at front, in a similar way to the Crop Sprayer
Tractor (8849).  It pivots around (or near to) the steering rod.  I
haven't added springs to it yet though.

3)
Shortened and straightened the front bucket assembly.  The original
setup didn't lift high enough, it was too long compared with a real JCB, and the bucket itself didn't have a good enough range of motion.
Following the holes in the beams can reveal the new layout for the
frame.  I then moved the pivot points of the bucket mechanism and
substituted the 5-hole yellow beams behind the front wheels with the
5-long flat beams from the rear bucket.

4)
I totally redesigned the back of the JCB because it wasn't realistic. 
The stands now comprise two pneumatic pistons that are supported by the
two 15-hole beams at the back, and two 11-hole beams that run front to
back underneath the mudguards.

5)
The close-up photo shows the pivot assembly which is, as a necessity
thus far, reinforced with tape.  The rotation is performed using the 
right-hand wheel as originally, to the outer bevel gears at the bottom, 
via a nasty gear train behind the rear wheels involving two bevel gears, a worm gear, a 24t crown wheel, two 16t gears, and six more bevel gears, in that order.

6)
I've modified the backhoe itself, mainly concerned with the pivot points of the arms and the pneumatic pistons to get greater range, and more depth for cutting trenches.  The double-acting pistons are much more powerful than the old design, so you can get away with a higher velocity ratio. However, I've used one of the old long pistons to operate the bucket because it needs the length of travel, and hence an extra valve is needed to switch between the old system and the new.  I don't know why the piston is wrapped in black insulating tape.

7)
Lots of extra bodywork, lights, and driver controls have also been added.  Ideally the wheel for the backhoe rotation would be moved to free up space inside the cab, but I haven't worked it out yet.

That's all for now.
Have fun. :-)