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#Post#: 4527--------------------------------------------------
1906 90CV Renault. The first ever Grand Prix winner
DIR By: Adrian
Date: August 21, 2021, 7:15 am
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I can't believe there is no build thread on my car and can only
apologise because it was an interesting build and since it was
my first cyclekart some of my methods may have amused you.
There is an article somewhere on building the wheels though.
Anyway, we are where we are as they so this little missive is
just to bring you up to date on what I have done to the Renault
to make it ready for Grimshorpe.
Because I fitted it with rear suspension there were a host of
things to consider in the design which, the more you thought
about, the more complicated they became. It's fair to say it was
a disaaaaaaaaster darling, the cart breaking down at every
opportunity.
The chain tensioner I fitted was not needed and made matters
worse so was removed and a new drive sprocket fitted.
Then the final drive chain kept jumping off the plate wheel
(sprocket) because the 'self aligning' design didn't work. (The
self aligning feature intended the two gears on the layshaft to
slide from side to side to keep the four chain wheels aligned).
When looked at from above, the axle and the layshaft were
parallel but when viewed from the rear they were very slightly
out of alignment and this caused the gears to 'walk' along the
layshaft causing the chain to hit the nut holding the clutch on
so it wasn't long before the clutch fell off all together.
(Thanks to everyone who picked up the bits from around the
track).
So the gears were aligned and fixed into place to overcome the
problem.
The evil forces causing the 'sprocket walking' now started to
'walk' the layshaft off to one side which caused the end of the
layshaft to drop out of the end bearing. Nothing broken but a
mess.
KISS, KISS, KISS. I kept hearing this and though I knew the
value of keeping this simple. Everything I did was to
accommodate the movement of the rear axle due to it being
suspended.
Last week I removed the engine and torque converter and cut away
the engine mounts and removed the layshaft and it's mounting
brackets.
I removed the bearings and everything that connected the axle to
the the springs but left the springs in place to look like they
still were a functioning part of the cyclekart.
I then offered up the engine and transmission to the chassis to
see how I could now refit it, remembering it had to fit within
the bodywork. No matter how I phased the TC I could not get the
assembly in so I bought a new centrifugal clutch, fitted it to
the engine and managed to install that reasonably easily. As I
write this, I am waiting for a new chain to arrive and when it
does all will at last be well and absolutely NOTHING can go
wrong! ;>)
The Renault is really easy to push now and feels a ton lighter.
I think all the efficiency losses in my original multi-chain
design have cost me dear both in reliability and performance and
this centrifugal clutch installation will result in vastly
improved reliability and better overall performance. I cant wait
to find out.
The new installation meant that the braking system had to be
re-designed so that was part of this weeks efforts too. Seems to
work OK.
I have also re-drilled the steering links to tighten the turning
circle so it should manage slaloms a bit better than it did.
Perhaps I should mention the braking issues I had and the cause
because it could happen to anyone.
Every time I took the Renault out the brakes failed almost
straight away, the pedal going down to the floorboard.
I kept bleeding the brakes but as soon as I went out on the
track again they would fail.
Now I don't know if you are aware of this but if you are not,
its valuable info.
Brake pistons press the pads against the brake disc when the
pressure is applied by your foot but to push the pads back off
the disc when you lift your foot off the pedal requires a force
from somewhere else. This force is applied by the piston seals
in the calliper which actually grip the pistons and returns them
back to the rest position once you take your foot off the pedal.
The reason for telling you about this is because the cause of my
problem was a warped disc. Every time the disc revolved the disc
would push the pistons back too far for the seals to hold and so
very quickly the pistons got moved further into the cylinders
than they should have. Far enough in fact to create a total void
in both cylinders of greater volume than one stroke of the
piston could supply. This loss of the required flow caused
complete loss of the hydraulic pressure. No brakes! A new brake
disc solved the problem straight away.
How did the disc get bent/warped. I think it must have been me
trying to reposition the carrier at some time which had become a
very tight fit on the axle, so beware of accidently bashing the
disc.
#Post#: 4534--------------------------------------------------
Re: 1906 90CV Renault. The first ever Grand Prix winner
DIR By: ChrisS
Date: August 21, 2021, 10:04 am
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Whar a brilliant reflection on your build, the good and the bad!
Builders take note!
Looking forward to seeing Renault reborn at Bourne!
#Post#: 4540--------------------------------------------------
Re: 1906 90CV Renault. The first ever Grand Prix winner
DIR By: TheGiantTribble
Date: August 23, 2021, 3:55 am
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So glad you stuck with it, and it does look go blasting round
the track!
Well worth all the effort you put into this.
#Post#: 4902--------------------------------------------------
Re: 1906 90CV Renault. The first ever Grand Prix winner
DIR By: Adrian
Date: October 17, 2021, 5:42 am
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Thanks in no small part to 'Jimmy de Fish', I think the Renault
is reliable now, well as reliable as it's ever going to be. If
you recall, the engine mount cracked and nearly broke in two as
we were whizzing around the Haynes track. I took it over to Jims
place and he sprinkled some of his Magic Dust on the engine
installation making it significantly stiffer and stronger. The
first testing was driving it around the industrial estate for an
hour or so, until the petrol ran out anyway. All seemed fine so
off to the show the following we went.
As it proved out, she was fine and went like the clappers to
with its GX Developments stage one engine. She accelerates well
but top speed is a little dissapointing so I'm and going to fit
a gold spring in the driven clutch and see what difference that
makes. Gluing another tooth on the pinion might work too?
Anyway, many, many thanks Jim. I think I can say she's finished
now but we all know better than that dont we?
On with the Wee Beastie now for next year.
#Post#: 4905--------------------------------------------------
Re: 1906 90CV Renault. The first ever Grand Prix winner
DIR By: jim
Date: October 17, 2021, 7:51 am
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You're very welcome mate. Looking forward to seeing you and the
Renault at Whilton.
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