scudderfish
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| posted on 23/3/15 at 09:38 PM |
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Why not just ditch the brake servo? I reckon most of the cars on here don't have one.
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peter030371
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| posted on 24/3/15 at 08:23 AM |
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quote:
Originally posted by scudderfish
Why not just ditch the brake servo? I reckon most of the cars on here don't have one.
What he said 
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drt
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| posted on 24/3/15 at 02:52 PM |
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I can see your point(s)
:p
I had the argument with myself, and several people...
If you do not instal a servo you have 2 choices (obvious sorry)
1) huge travel and low (required) pedal force
2) huge pedal force and small travel
Even if you would vary the master cilinder piston diameter
I have a autograss buggy thing, and although it only weighs 390kg you really have to STOMP it
if you want some stopping power... so much so that I am not able to heel-toe in it.
I know most -if not all- kitcars,locost do not have a servo...
So hom much pedal force do you have to exercise ?
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peter030371
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| posted on 24/3/15 at 04:30 PM |
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My previous experience of a non-servo'd Striker (circa 530Kg plus me and the passenger) over 18 years of use is that a firm pedal pressure is
required but I could heel and toe and I could lock the wheels if i got a little carried away/ over excited on the track  The feedback was very good
without a servo and I would have hated to have lost that 'feel'.
My current Striker still has not got an engine or brake fluid so no idea if that is worse or better 
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drt
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| posted on 24/3/15 at 06:37 PM |
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Doing the maths comes up with 35.77Kg of foot pressure during 1G braking (idealized)
Sounds like a lot ?
piston diameter 0,048 m
Displacement brake pad 0,002 m
vehicle weight 500 kg
Braking 9,81 m/s^s
Braking torque, ideal brake distri, 1 wheel 927,936 Nm
Brake friction coeff 0,35
Saab 93 brake master cil bore 0,0238 m
pedal ratio 4,89
Mean brake disc radius 0,19 m
n number braking surfaces 2
Brake pad surface 0,005 m^2
Brake pad force 6976,962406 N
Pressure on brake piston 963904,5614 pascal (N/m^2)
force needed on master cilinder 1715,291053 N
Displaced volume brake caliper 3,61911E-06 m^3
Needed master cilinder displacement 0,813501871 cm
pedal displacement @ foot 3,97712026 cm
Pedal force @ master cilinder 174,8512796 kg
Pedal Force @ foot 35,76503446 Kg
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coozer
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| posted on 24/3/15 at 06:56 PM |
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Good work, just a quickie, how you going to route gear cables, water pipes and whatever round the fuel tank? Over, under or to the side?
Are you running the water pipes down the centre? That's assuming the rads going to the front?
Steve
1972 V8 Jago
1980 Z750
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drt
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| posted on 24/3/15 at 07:26 PM |
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quote:
Originally posted by coozer
Good work, just a quickie, how you going to route gear cables, water pipes and whatever round the fuel tank? Over, under or to the side?
Are you running the water pipes down the centre? That's assuming the rads going to the front?
Steve
Gear cables are going over, electrics to the side (away from exhaust) and water... wel
I was planning on sticking a rad in a pontoon... and the intercooler on the other side.
Thus choosing mass centralization over ideal weight distribution.
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scudderfish
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| posted on 24/3/15 at 07:38 PM |
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quote:
Originally posted by drt
Doing the maths comes up with 35.77Kg of foot pressure during 1G braking (idealized)
Sounds like a lot ?
piston diameter 0,048 m
Displacement brake pad 0,002 m
vehicle weight 500 kg
Braking 9,81 m/s^s
Braking torque, ideal brake distri, 1 wheel 927,936 Nm
Brake friction coeff 0,35
Saab 93 brake master cil bore 0,0238 m
pedal ratio 4,89
Mean brake disc radius 0,19 m
n number braking surfaces 2
Brake pad surface 0,005 m^2
Brake pad force 6976,962406 N
Pressure on brake piston 963904,5614 pascal (N/m^2)
force needed on master cilinder 1715,291053 N
Displaced volume brake caliper 3,61911E-06 m^3
Needed master cilinder displacement 0,813501871 cm
pedal displacement @ foot 3,97712026 cm
Pedal force @ master cilinder 174,8512796 kg
Pedal Force @ foot 35,76503446 Kg
Assuming you weigh circa 70-80kg, that is about the force you feel on the sole of your foot when you are standing up.
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drt
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| posted on 24/3/15 at 07:51 PM |
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Assuming you weigh circa 70-80kg, that is about the force you feel on the sole of your foot when you are standing up.
I'll take that as a very optimistic compliment ^^
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drt
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| posted on 27/3/15 at 11:53 AM |
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So, I'm dumping the servo
thanks for the tips!
Now, this is the master servo.
How would you link that up? As the shaft does not describe a straight movement (due to pedal... etc etc you know)
A shaft with a 'spherical' end (ball) could work, but i'm scared about radial force on the plunger.
Because the saab converts the movement before the servo to straight (linear).
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peter030371
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| posted on 27/3/15 at 12:29 PM |
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They normally have a clevis pin on the end but not sure how you would fit one to that master cylinder.
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drt
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| posted on 3/7/15 at 08:22 PM |
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During these last months I have been busy with our uni's ecomarathon team pushing 700 hours since February... besides normal classes...
Not a lot of time for personal indulgences 
Machining the brake shaft so it works without the servo
finished product
A lot more room now XD
In the meantime trying to get the molds done... this is the airscoop
And this the bottem of what is going to be the bonnet mold
An overview, Thinking of housing the rads and IC over there ... mass centralisation and shorter water/air lines
Because of my geometry, this is the only spot the rack could be in :s
Bonnet mold almost there
And a delivery of brake stuff
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drt
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| posted on 14/7/15 at 01:48 AM |
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I've been waiting for news from RD for weeks
So, I'm doing detail work... front lights tonight
And the girlfriends car needs attention...
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drt
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| posted on 15/7/15 at 12:01 AM |
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Today... a day of angry phone calls
...rear lights
...and setting up the rotaxmax for a week @ Spa (promised the misses 'spa' don't think she really gets it though XD)
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drt
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| posted on 11/8/15 at 11:13 AM |
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So a whole week at the Spa Karting 25°-30°C and mostly dry.
Now she needs a top end rebuild, anyone knows somewhere I can get rotaxmax parts cheap ? Over here it's 500 smackeroonies... because you can
only let it be done.
Build a small furnace... I got her up to over 1000°C, now i can cast my own ally parts.
First use was to make a ring for my girlfriend (had to make up for the Spa thing)... :p Silver is surprisingly easy to work with! and under the
current raw silver price it was very cheap ^^
I have been waiting months for Rally design parts... really wondering if I would still place my orders there, the costumer service is a trainwreck.
Anyone having problems ?
To top it all I ran out of Argon, and over here all building sector and related companies are closed for a 3week builders holiday... no gas for me
then.
Easing the pain with turning a gearknob
Thinking about using the Saab mirror glas in a DIY side mirror... because they are heated making life so much better when it's cold or starts
to rain...
if they only weren't so vast.
Engine is in for the xxxxtime
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drt
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| posted on 11/8/15 at 11:25 AM |
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Oh, I have been meaning to ask.
The original atom uses separate front parklights/daytimerunninglights...
Looking at the model they are crystalight ?
If so, they only sell reversing lights... who would be way too bright/diffuse to pass an iva :s
Anyone knows what they are ?
see->
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drt
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| posted on 11/1/16 at 11:16 PM |
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It's been a while
testing the look in real life for the first time... before starting making the molds and ultimate products
vast amounts of resin, glass- and carbon weaves arriving along with corque sandwich material... postman sure loves me :p
sanding all the wood models for the last time before the varnish coat(seallent)
making parts for new steering arms... as the original ones had dreadful Ackermann, even without the change in wb and track
For a long time I was planning on using an LED as an reserve fuel warning light, just by adding resistors so that when the float reaches zero (aka
lowest resistance) the power in the circuit would be +- 5v... a very simple, light and elegant solution... but turns out LED's aren't as
picky as I thought... the lit up as soon as 1.5v getting ever brighter,
too bad... have to stick in a gauge
And then this disaster, I was planning on using the Saabs fuel pump as a piggy-back on my tank... turns out a Saab has just the one pump in the
tank.
Thus it has internal passages to avoid air bubbles (it's a rotary pump, can't suck air) These are impossible to close of, so can't
use the pump outside the tank... need to use the whole original plastic nightmare or buy a specific new one.
Keeping it locost by reworking the tank so to use the original.
This needs a bigger hole and bigger lowest fuel gathering compartment.
needed to go to, because of packaging the fuel nozzle is moving to the other side
To add to all that, I've just ordered jet cutted parts the week before; So I'll make the pump fitting the old fashioned way
The lid
the new set up, not very pleased with this
My tank is much higher than a Saab one, so this had to be lowered to
Now I'm waiting for some quite days to do all the composite work in one go
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drt
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| posted on 14/1/16 at 12:59 AM |
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took her out to clean the hangar
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peter030371
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| posted on 14/1/16 at 08:11 AM |
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Looking good, we have all sat in our chassis at some point and gone 'brum brum'
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drt
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| posted on 14/1/16 at 01:20 PM |
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Getting very eager to get to do it for real
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jimmyjoebob
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| posted on 14/1/16 at 05:28 PM |
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Build looks great - what make are the seats you are using and how much do they weigh?
If at first you don't succeed, hide all evidence you ever tried!
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drt
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| posted on 1/2/16 at 11:26 PM |
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quote:
Originally posted by jimmyjoebob
Build looks great - what make are the seats you are using and how much do they weigh?
Sorry for the late reply.
I got the seats here;
,2 x BLACK BUCKET SEATS. PLASTIC 4x4 kitcar, beach buggy, Boat.
Very good service ! very good seats... I must warn that they are BIG...
much much bigger than the GFRP's I had (kitspares type ones).
But fit me very nicely !
But you'll need some space in your vehicle.
I didn't weigh them yet, the fabricator states 7.5kg a pop.
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drt
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| posted on 17/2/16 at 12:20 AM |
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repositioned the gear selector again, somewhat higher and more back... much more ergonomic and now with a tiny throw
postman came by
I couldn't help myself XD
love the sound dampening qualities
I don't believe you guys have this in the uk ? Cheap as chips! and works so good... it could strip the grease of a steam engine
the end of another late night
spot the pun... it was only a matter of time this washed up
After a lot of careful cutting and consulting the cad model...
exhaust completed... now only wait for 2 Vbands to come in and weld it all up
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drt
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| posted on 17/2/16 at 10:17 AM |
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tips on how to polish the dull stainless pieces to suit the mirror finish of the damper, please do not hesitate
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drt
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| posted on 4/3/16 at 01:24 AM |
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Who needs a lasercutter when you have a nice angle grinder
The new gearselector in place, I'll be adding some structure to it later to give it lateral stiffness... and remove the now obsolete parts
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