Pages: [1] 2 3 ... 10
 on: Today at 09:34:48 AM 
Started by Donk - Last post by Thunderace
sixty five miles east north east of Cullompton,
but I can still wave for sure.
(1970 Van der Graaf Generator album ?)

 on: April 22, 2018, 10:30:48 AM 
Started by Donk - Last post by bondbugdave
Welcome to the group Donk. Strait jackets are on the left, meds (doughnuts) are on the table, and if you hurry you can still get a seat in group therapy. HAVE FUN!

Must get clarification on how you came to be known as Donk, anything to do with crocodile dundee?

 on: April 22, 2018, 10:24:49 AM 
Started by Donk - Last post by Donk
Just a note to say hello to all.
Joined BTW area1 two week ago meet up with area1 in Honiton two week ago they are a good bunch.
I live in Cullompton love to get out and about on my Triumph speedmaster trike when I can.
I am 56 years old and most people call me Donk
I have had my trike for about 8 months now and love it.
Hope to see you all out and about if you see me just give me a wave.

 on: April 07, 2018, 05:43:37 PM 
Started by Thunderace - Last post by Thunderace
At some point no doubt some wit will question
'how you gona reach the handlebars' ?

(looking at the neck being several feet away from pilot's seat)
Ok this is where the magic happens,
because the neck is kicked out at forty five or more,
and the bars are aligned at a similar angle,
the distance the bars come back towards you is given by
(raise+pullback)x 0.7

while the height that the bars arrive is
(raise-pullback)x 0.7

So taking a pair off the shelf apehangers, 19 raise 7 inch pullback,
you get the grips back towards you 26x0.7= 18 inches
while we had come up 12x0.7= 8 1/2 inches.

We can add risers and get more,
stuff another dozen inches between the clamps and top yoke,
and now the bars have come back 26 1/2 inches,
but are still only seventeen higher than the start point,
which if the neck is about the same height as your seat,
brings the bars to somewhere near sensible,
even though the neck was more than four feet away from where we sat.

Ok some will straight away claim that the same could be achieved by having the neck
higher and closer.
however there are two issues,
first is that keeping the neck low reduces the torsional forces,
the second is where you then put your feet ?

I am going to let you think about that one for a while.   

 on: February 11, 2018, 12:28:34 PM 
Started by Thunderace - Last post by Thunderace
When it comes to available powerplant configurations,
there are various to choose from,
the most common arrangement available tends to be Giacosa style side mounted gearbox.

This is largely the industry standard for FWD platforms,
first off it probably looks less than useful, with the engine offset to one side,
however it's often quite a compact package which would fit in the Servi car's rear box.
(with space to spare).

The smaller cc units are typically only about twenty two inches tall,
while larger are often canted as stock to achieve similar,
which means the cam cover sticks up some thing a little over six inches higher than our upper front frame tubes.
As long as passenger(s) are sat a little further back,
this need not force the rear seat to be insanely high perched (chicken on a gate),
big wild swoopy king and queen seat and you can hide the little bit where the engine sticks up in the hump between the two seats.

Aesthetically it tends to look better if the trike has maybe a dozen inches or so of rear overhang,
while noticeably aft of the engine is a big space,
up to you what you use the space for,
but just don't ignore it !
As I say the engine being offset does make for some interesting bracket making,
you may have to come out a little wider on the bottom rails,
or head towards a semi-punt chassis style thing,
but main thing would be that since eighty percent of modern cars are this way,
there are a huge choice of donors.

Less common are the longitudinal mount,
My Subaru is of this type, as are many Audi's, Bigger Renault's, various Italian,
and a few others.
First off while at least more symmetrical (to a degree),
the engine sticks up right about where you want to be sitting.
options are to run the shafts at a slight angle forwards (often how it was in the car),
and extend the wheelbase a little so you can sit sit low ahead of the motor.
This is a real easy way to go for sure,
and makes for a great trike.

However the other option is to angle the shafts a little aft,
and thus sit behind the engine,
It's a bit tight for space for sure,
as a single seater fine,
but as long as you and your passenger ain't too fat,
typically pilot is sat on axle line, passenger at little behind,
you may have to come up an inch or two on the seat and pegs so legs miss hot stuff.
but yeah probably the most fun design.
And there are a few ways to gain a bit more space,
which we will look at later.

Other configurations,
AP four speed and Saab BW35/37
Leyland, Austins, A series, Maxi, Allegro, Saab 99, 900 etc,
Gearbox bolts in place of sump.
Does make the thing tall, but less wide, split rear seat is probably good.

GM's THM425, & 325,
bit rare this side of the pond, but not impossible to find,
these are a 'folded' longitudinal mount,
with a Morse chain driving a reverse running GM Turbo 400,
It's the 'Lego' block of building weird stuff,
bell housing is Buick so Rover V8 will fit.
Only really useful if you are doing a V8,
these came fitted to GM's 'E' platform, 66 to 85,
Eldorado, Riviera, Toronado, etc (all very ugly cars).

Possibly more interesting for the trike builder,
across the pond people bolt the German made Getrag diff unit,
from a C5 corvette in place of the tailshaft housing of an old GM Powerglide.
This looks like it's just the animal we needed for sure,
(ie would give a nice usable axle to engine mount relationship distance)
as yet I have not figured how we replicate the same here,
Getrag diffs obviously are available, as are short case inline transmissions.

(Google image search 'C5 diff powerglide' if you need a picture)

For sure to a degree the style of machine one has in mind to build
may tend to make one of the engine/transmission arrangements look more attractive.
Though it probably should be born in mind that mostly they fitted an under bonnet space
smaller than the Servi-car's Ice-cream box !

While keeping the weight of the power unit close up to the axle was good,
in so far as it gets the major weight of the trike on those fat rear tyres,
I would admit that we might have wanted the engine to mount a little further forward,
just for the look kind of thing, maybe eighteen inches to a foot ahead of the axle line would look good.

Boyd Defrance did this
On Tom Mcmullen's Famous Corvair trike.
Completely mad.

Realistically looking at the Subaru/Audi/etc longitudinal mount,
the engine mount face is usually seven inches forward of the diff outputs,
and while the drive shafts can stand a few inches of angle,
this still leaves us a few inches shy.

One possibility for sure is to add spacer between the crank and flex plate,
and the same tween engine and trans,
and thus move the engine forward by however many inches were needed.
This is how my 'CandyBox' reliant/VW was done,
(admitted that was on a manual box, but a auto is easier).
Obviously this is only works with longitudinal mount tranaxles,
and limited inches,
while an support bearing could be added in order to allow greater,
it's just pushing the weight forward,
and probably more useful to look at the space behind the axle line.     



 on: January 21, 2018, 04:22:23 PM 
Started by Thunderace - Last post by Thunderace
Another issue I meet repeatedly is that of 'ground clearance',
ether too much or too little and often different at the two ends,
(so the frame don't sit right).

I tend to construct around the engine/gearbox unit sat on the bench,
it's easier to work this way, and I have a bad back.
The Yanks have a concept they call 'scrub line' ,
which is a line bellow which nothing must hang.
So an easy way for us trike builders was to make the top of the bench be the 'scrub line'.

Measuring off the bench top gives a fixed datum,
allowing seat, neck and axle heights to be more accurately determined.
Five to seven inches was probably reasonable as ground clearance/scrub line,
So go middle with six for now,
I subtract six from any vertical measurement and that gives me distance above bench.

So seat (19 to 26 inches ) becomes 13 to 20 as measured off bench top,
top of the neck comes 19 inches for stock length forks and a 'normal' (24" rolling) wheel/tyre combo,
and the centres of the two rear hub bearings 6 inches above the bench,
again for normal 24" rolling diameter rubber,
(subtract or add one for low profiles or old tall tyres).
add 1.4 to neck height for every two inches over on forks*

There probably is a limit to the usefulness of going longer on the forks.
Ascetically it's sometimes fun,
but it needs not to be at the sacrifice of increased neck height,
lower neck reduces torsional forces and makes it easier to reach the bars.
(well given some risers and apehangers it was gona for sure).

If you are making your own front end anyway,
there probably is some justification to shorter forks,
four under (26inch) forks is as far as you can go without swapping to a scooter wheel,
but this drops the neck nearly three inches,
which probably allows for six more in the length of the spine,
with the bars still ending up 'reading newspaper comfy chair' no problem.

Similarly when it comes to footrests,
particularly if you are doing 'forward sets'
typically it's useful to come up a few inches,
footrests don't need to be right down low,
it's more comfortable and practical on a trike to bring the pegs up,
measured off the bench top six to a dozen inches is not unreasonable a height.
This allows plenty of space for linkages,
and avoids master cylinders hanging bellow frame tubes and other horrors.   


Pages: [1] 2 3 ... 10