Hi
I have assembled the front end to day and now deciding where to put the top shocker mount
Do I put it on the side of the top rail
In both positions I am getting about 40mm of travel on the shocker
Or under side of top rail
On side of top rail
Been told they are best stood up but please comment
I think under side would be better and more consealed
Comments welcome Please
There are more photos in my photo archive under front end
I would mount it under the chassis rail for two reasons, 1/ it looks neater, and is better for IVA. 2/ you will get "slightly" more travel as its on more of an angle. HTH Ray
In the ideal world it should be placed were the load path passes through the center of the supporting chassis rail
tilly
quote:
Originally posted by tilly819
In the ideal world it should be placed were the load path passes through the center of the supporting chassis rail
tilly
Mine are as your lower photo but connected to each end of a rail that is welded to the underside of the upper chassis rails, also cross braced to the bottom rails. Well I know what I mean........
Was thinking of lining the top eye around here and putting a channel across from the outer toprail the the cross support thar is 5" inside.
Better on the outside of the rail to keep it more upright. More angle needs stronger springing.
IIRC if you place them on the inside of the chassis you'll get a more pronounced spring fall off rate- the more vertical the better.
Instead of just guessing you should sketch it up and check the installation ratio / suspension rate, really you want it to have a constant or
'rising rate'.
I.E for every 1mm of the wheel the shock compresses by Xmm, ideally with X being constant or increasing for each consequtive mm of wheel movement.
If you don't check and have X decreasing for each mm of wheel travel then you will end up with some very odd handling, especially in roll.
This is very basic input though.
Is this position not defined in 'the' book?
[Edited on 31/5/11 by Doctor Derek Doctors]
Looked in Book and it does not say where to mount the top mounting brackets
some pictures show on side of top rail and some photos show it under side of top rail ??
quote:
Originally posted by Trollyjack
Looked in Book and it does not say where to mount the top mounting brackets
some pictures show on side of top rail and some photos show it under side of top rail ??
Thats Brill
I'll measure next time i'm at my lock up
Kev
Simply Try to mount the shocker unit as vertically as absolutely possible. ..
Save yourself a maths exercise to tell you exactly that .
Wouldn't overly worry about structural 'niceities' as even the suspension pickup points on these Locost chassis are just daft/poor .
The mount ears have been documented to fatigue off due to their poor placement and inadequate support.
Shock mount 'strength' is the least of your worries.
[Edited on 1/6/11 by Bare]
Length of lower wishbone pick-up to lower shock mount = 225mm
Angle between the line (between the above two points) and the horizontal Plane (floor) = 0°
The distance between the lower wishbone mount and the center of the chassis top rail. = 270mm
Angle between the line (between the above two points) and the horizontal plane (floor) = 74°
Open and closed length of the shock = 320mm open 255mm closed with rubber bump stop 235mm with out
Overall length of the lower wishbone. 340mm to centre od bottom ball joint.
I have drawn it up on a cad package but not ver good at it yet I can email you the DFX file if you wish
quote:
Originally posted by Trollyjack
Length of lower wishbone pick-up to lower shock mount = 225mm
Angle between the line (between the above two points) and the horizontal Plane (floor) = 0°
The distance between the lower wishbone mount and the center of the chassis top rail. = 270mm
Angle between the line (between the above two points) and the horizontal plane (floor) = 74°
Open and closed length of the shock = 320mm open 255mm closed with rubber bump stop 235mm with out
Overall length of the lower wishbone. 340mm to centre od bottom ball joint.
I have drawn it up on a cad package but not ver good at it yet I can email you the DFX file if you wish
I had the same dilemma when i built mine and remember something about the mounting bolt being hard to fit when under the chassis rail as it was tight
to the Fu tubes.I fitted the brackets to the outside of the chassis rail and made a wedge section that fitted between the rail and bracket to make it
parallel to the lower mounting bracket .I thought the shock being more upright was the best way to have it and as mentioned the spring rate can be
lower and wont tend to end up as a falling rate as could happen if mounted under the rail and to far in board.
Paul
Right then.
With those dims you cant put the shock directly inline with the chassis rail as you will have a very high ride height or your shock will be nearly
fully compressed to keep that angle of the wishbone.
I have made an assumption that the centre of the shock top mount will be 40mm away from the centre of the chassis top rail (to give clearance) and
that you will have 30-35mm of droop and 60-65mm of bump.
Inside mount:
-30 = 312.783
-20 = 307.713 = 5.07
-10 = 302.579 = 5.134 = 0.064
0 = 297.38 = 5.199 = 0.065
10 = 292.118 = 5.262 = 0.063
20 = 286.792 = 5.326 = 0.064
30 = 281.402 = 5.39 = 0.064
40 = 275.947 = 5.455 = 0.065
50 = 270.429 = 5.518 = 0.063
60 = 264.846 = 5.583 = 0.065
Outside Mount:
-30 = 315.486
-20 = 309.505 = 5.918
-10 = 303.469 = 6.036 = 0.118
0 = 297.38 = 6.089 = 0.053
10 = 291.328 = 6.052 = -0.037
20 = 285.044 = 6.284 = 0.232
30 = 278.798 = 6.246 = -0.038
40 = 272.502 = 6.296 = 0.05
50 = 266.157 = 6.345 = 0.049
60 = 259.762 = 6.395 = 0.05
The first number is the suspension travel (- = droop, + = Bump) The second number is the shock length, the third number is the change in shock length
and the forth number is the change in shock rate.
In my conclusion mounting inside will give roughly a 5:10 installation ratio, mounting outside will give a 6:10 installation ratio thus outside would
be stiffer with the same springs.
What's interesting as that mounting inside gives a lovely constant (amazingly constant) figure for the rate increase (0.063-0.065mm) over the
entire travel of the shock which is ideal, whereas the outside mounted shock has a very erratic change of rate (-0.037-0.232mm) which will give odd
handling.
If it was my car I would mount the shock inside to give more constant and progressive damper/spring travel with a constant rate increase, it will also
allow you to have a longer wheel travel (also more ride height adjustment) and it will be a much neater finish to the car.
Hope that helps.
So are you saying that the top mount is to be inside the top rail
where exactly is it to be, on the centre line of the top rail or under neath ?
could you you email me a sketch Please
quote:
Originally posted by Trollyjack
So are you saying that the top mount is to be inside the top rail
where exactly is it to be, on the centre line of the top rail or under neath ?
could you you email me a sketch Please
Thats brilliant thanks very much for you time, it has been much appreciated
By luck my idear was not too far away
now to manufacture the top bracket I intent to make this out of Stainless to give it better strength.
No Probs mate, I tried to base it on your initial projections to make something manufacturable.
Have fun building, I wish I could get some time to do some practical work rather than being in front of the desk.
quote:
Originally posted by Bare
Simply Try to mount the shocker unit as vertically as absolutely possible. ..
Save yourself a maths exercise to tell you exactly that
quote:
Originally posted by Bare
Simply Try to mount the shocker unit as vertically as absolutely possible. ..
Save yourself a maths exercise to tell you exactly that .
Wouldn't overly worry about structural 'niceities' as even the suspension pickup points on these Locost chassis are just daft/poor . The mount ears have been documented to fatigue off due to their poor placement and inadequate support.
Shock mount 'strength' is the least of your worries.
[Edited on 1/6/11 by Bare]
quote:
Originally posted by Neville Jones
quote:
Originally posted by Bare
Simply Try to mount the shocker unit as vertically as absolutely possible. ..
Save yourself a maths exercise to tell you exactly that .
Wouldn't overly worry about structural 'niceities' as even the suspension pickup points on these Locost chassis are just daft/poor . The mount ears have been documented to fatigue off due to their poor placement and inadequate support.
Shock mount 'strength' is the least of your worries.
[Edited on 1/6/11 by Bare]
That statement above is about right on every count. What oriface DDD pulls his info from I don't know,( Wikipedia?or the same place as the ship's engineers?) but as the shock inclines from the vertical, once you get past about 10 degrees, things start to go way past non linear in the non desireable direction.
The locost setup puts some limits with the top wishbone design, and clearance for the coilover setup.
There are other ways of mounting the top shock bolt. I'll try and post a pic.
And yes, accepted practice among knowledgeable suspension designers would be to mount the shock as close to vertical as possible, with enough inward inclination to give a rising rate up to the point of max bump, where the shock would be 90 degrees to the wishbone.
Well, that's how the couple of designers I've met would do it.
Cheers,
Nev.
quote:
to manufacture the top bracket I intent to make this out of Stainless to give it better strength.
quote:
Originally posted by Doctor Derek Doctors
In my conclusion mounting inside will give roughly a 5:10 installation ratio, mounting outside will give a 6:10 installation ratio thus outside would be stiffer with the same springs.
Hope that helps.
i'm confused, as a leyman, DDD's proposal and numbers seem very convincing... but then i can't claim to understand what the numbers
mean...
what was your job title again DDD?
quote:
Originally posted by paulf
quote:
Originally posted by Doctor Derek Doctors
In my conclusion mounting inside will give roughly a 5:10 installation ratio, mounting outside will give a 6:10 installation ratio thus outside would be stiffer with the same springs.
Hope that helps.
Are you sure that you got this the correct way around? surely the nearer vertical the damper is then the stiffer the effective spring rate.
Paul
quote:
Originally posted by Neville Jones
quote:
Originally posted by Bare
Simply Try to mount the shocker unit as vertically as absolutely possible. ..
Save yourself a maths exercise to tell you exactly that .
Wouldn't overly worry about structural 'niceities' as even the suspension pickup points on these Locost chassis are just daft/poor . The mount ears have been documented to fatigue off due to their poor placement and inadequate support.
Shock mount 'strength' is the least of your worries.
[Edited on 1/6/11 by Bare]
That statement above is about right on every count. What oriface DDD pulls his info from I don't know,( Wikipedia?or the same place as the ship's engineers?)
quote:
Originally posted by mrwibble
i'm confused, as a leyman, DDD's proposal and numbers seem very convincing... but then i can't claim to understand what the numbers mean...
what was your job title again DDD?
quote:
Originally posted by Doctor Derek Doctors
quote:
Originally posted by mrwibble
i'm confused, as a leyman, DDD's proposal and numbers seem very convincing... but then i can't claim to understand what the numbers mean...
what was your job title again DDD?
They aren't my numbers really, I just put Trolleyjacks suspension into a standard 2D layout of front suspension and then moved the wheel by 10mm at a time and wrote down the numbers that came out. they would have been the same had anyone done them
Job title? Well technically I'm listed as Mechanical Engineer / CATIA V5 Designer but at the moment there is stuff from Fluid and Thermo dynamics, Man' Eng and Material involved as I'm working on a major project for a future Formula 1 car.
quote:
Originally posted by mrwibble
quote:
Originally posted by Doctor Derek Doctors
quote:
Originally posted by mrwibble
i'm confused, as a leyman, DDD's proposal and numbers seem very convincing... but then i can't claim to understand what the numbers mean...
what was your job title again DDD?
They aren't my numbers really, I just put Trolleyjacks suspension into a standard 2D layout of front suspension and then moved the wheel by 10mm at a time and wrote down the numbers that came out. they would have been the same had anyone done them
Job title? Well technically I'm listed as Mechanical Engineer / CATIA V5 Designer but at the moment there is stuff from Fluid and Thermo dynamics, Man' Eng and Material involved as I'm working on a major project for a future Formula 1 car.
well i'm sure your a very clever man. i don't understand why someone has been so rude to you for trying to help someone with their build...
quote:
Originally posted by britishtrident
quote:
Originally posted by mrwibble
quote:
Originally posted by Doctor Derek Doctors
quote:
Originally posted by mrwibble
i'm confused, as a leyman, DDD's proposal and numbers seem very convincing... but then i can't claim to understand what the numbers mean...
what was your job title again DDD?
They aren't my numbers really, I just put Trolleyjacks suspension into a standard 2D layout of front suspension and then moved the wheel by 10mm at a time and wrote down the numbers that came out. they would have been the same had anyone done them
Job title? Well technically I'm listed as Mechanical Engineer / CATIA V5 Designer but at the moment there is stuff from Fluid and Thermo dynamics, Man' Eng and Material involved as I'm working on a major project for a future Formula 1 car.
well i'm sure your a very clever man. i don't understand why someone has been so rude to you for trying to help someone with their build...
+1
DDD,
Considering that my work has involved motorsport design, and I have many years of experience, and my statements have been corroborated by at least two
other bona fide engineers, then I have every right to question the extremely poor solution you have put forward to the gent asking the question.
To lay the coilover at the angle you suggest, will impart high loads into the top mount and wishbone, and also give undesireable behaviour to the
system.
My explanation was quite simple, and states what is considered to be the accepted normal practice when designing a suspension system of this type. As
I have done far too many times past.
Working in F1 doesn't make anyone a genius or expert, sometimes quite the opposite, and maybe more than a little lucky, as you pointed out.
And as I've stated many times, there is far too much wrong information on this forum, and the internet in general, and if I can stop just one
person from coming to grief because of these misleading statements, then I can say I've done good.
Cheers,
Nev.
[Edited on 3/6/11 by Neville Jones]
Hi
One quick glance at that lot on the pics shows that worrying about a few mm of travel on the damper is the last of your worries. Id be way way more
concerned about the camber gain problems your going to have with that layout on the pickup points of the arms. But as it stands simply move the base
damper mount out as close to the bottom ball joint as is practical and mount the top mount out on the side of the chassis to gain as much damper
travel per wheel travel as possible. You can use a basic ruler for that.
But then again assuming this is just a ROAD use car leave as is and stop worrying. It is still far better than whats available from some of the kit
manufacturers with the top bracket in either position.
Cheers Matt
Just read all the comments above and my head is now spinning
What to Do now ??????
quote:
Originally posted by Neville Jones
DDD,
Considering that my work has involved motorsport design, and I have many years of experience, and my statements have been corroborated by at least two other bona fide engineers, then I have every right to question the extremely poor solution you have put forward to the gent asking the question.
To lay the coilover at the angle you suggest, will impart high loads into the top mount and wishbone, and also give undesireable behaviour to the system.
My explanation was quite simple, and states what is considered to be the accepted normal practice when designing a suspension system of this type. As I have done far too many times past.
Working in F1 doesn't make anyone a genius or expert, sometimes quite the opposite, and maybe more than a little lucky, as you pointed out.
And as I've stated many times, there is far too much wrong information on this forum, and the internet in general, and if I can stop just one person from coming to grief because of these misleading statements, then I can say I've done good.
Cheers,
Nev.
[Edited on 3/6/11 by Neville Jones]
While Nev is not particularly tactful in his reply, his information is as well founded as it comes I am afraid. Coupled with Matts comment above.
With outboard shocks on a seven type car its nearly impossible to get the ideal set up as they sit at such a shallow angle. If you are that determined
to get it as good as you can then start looking at inboard shocks and at better suspension geometry overall.
Shock on outside point, get the bone mount as far out as possible as recommended by Matt, personally I do not like forcing the wishbone to act as a
lever, you just load up both ends anyway.
You do need to try and get more travel on that shock, its nearly closed in droop, this achieves this.
My qualifications are none BTW
This is the front of a winning Brabham for reference, okay its 30 years old so a load of old tat!
nb/ do not agree with all the nasty comments, pointless and rude on both sides.......
[Edited on 3/6/11 by mark chandler]
quote:
Originally posted by Doctor Derek Doctors
Seriously, get a life.
I've got a sense of humour instead. You might get the same.
Nev, with all respect to all your wisdom and experience. Can you back your story up with numbers and proven examples? Like you say yourself... there
is a lot of false information out there. Why should anyone assume your information is indeed right.
What went wrong with DDD's calculations? Instead of burning him to the ground, maybe you could give him some pointers where to look out for or
some secret parameter we meager mortal humans don't know about.
And yeah maybe DDD doesn't present himself in the smartest way possible, and yeah he might often give wrong advice. But instead of just burning
him to the ground, maybe you could help him a little so he might get it right next time. And help many people to the right information.
Because not only are you burning DDD down to the ground. Trolleyjack still doesn't know how he should do it.
Oh please allmighty Neville Jones, please share some of your infite wisdom with us lower humans.
PS: I for one would be interested to learn a bit more about this subject as I'm trying to work out a chassis design. Wich might get built
someday, but till I get the chance to do so I enjoy doing some design work.
PSS: Yes you should read this post with your sense of humor turned on.....
When somebody shouts about how bright they are and denigrates others we know exactly what they are.
About 20 years back I used to share a lunch table with a guy who was later nominated for a Nobel prize he was very quiet and unassuming but he was
the real deal.
OK, sense of humour turned up and sarcasm alarm turned down..... And aware that a couple of wannabe's are gunning for me... ( If they had any
sort of engineering education, then they would not be saying what they are, and would understand what I've said. Flakmonkey IS an engineer, thus
his comments.)
Short of taking a lot of time to do a bundle of sketches, I'll try and explain in words. (A picture is worth a thousand words, I know, but
anyway....)
Draw a bottom wishbone, inner pivots and coilover mount at the outer end.
Now draw a coilover at the outer pivot, at 90degrees to the wishbone.
Any load put upwards into the coilover, from the wishbone, at this point will be directly along the axis of the coilover, so the full rate of the
spring can react to it.
Now draw the coilover at an inclination inwards towards the chassis, with the bottom pivot still in the same place on the wishbone.
A vertical load at the coilover pivot is reacted only by the vertical component of the coilover. As it is inclined, the coilover will be pushing
outwards on the wishbone as well. This should be fairly easy to see. As the top of the coilover is now inclined even more, the outward push increases
in relation to the sine of the inclination angle, and the vertical decreases with the cosine. Thus, a heavier spring is needed to give the same
vertical force at the pivot, as would be required if the coilover was vertical or close to it.
At 10 degrees inclination, the cosine is 0.9848, the sine is 0.1736. So, if the spring in the coilover is pushing along its axis with 100 lb force,
then 17.36 lb force wqould be acting outwards, and 98.48 lb force would be acting vertically at the wishbone pivot. At 15 degrees, these figures go to
96.59, and 25,88. 20 degrees then gives 93.96 and 34.2. If you graphed these, you would find that they would follow a sinusoidal graph. Up to about
20 degrees, things are fairly linear, but most would prefer to keep the angles as low as possible. Once you get past 20 degrees, the vertical
component decreases at an increasing rate, and the horizontal increases.
That about sums it up.
So, if you put the coilover at 90 degrees to the wishbone when at the max travel up of the wishbone, the force seen by the wishbone will be increasing
as the cosine decreases. Rising rate. Quite simple.
With a Locost book situation, it is difficult to achieve what I've just outlined. However, the top of the coilover should be as near to vertical
as is possible geometrically. This will probably put the top mount some distance from the chassis, and needs to be dealt with by adding an extra tube
laterally, attached to the chassis and picking up the top coilover mounts. This would do the same job as what is commonly known as a 'strut
brace' on tin tops.
Clear as mud!
Cheers,
Nev.
[Edited on 4/6/11 by Neville Jones]
Thank you for this constructive post Nev. I'd offer you a drink if we were in a bar. But sadly I don't feel like swimming across the pont
tonight 
It's hard to find good sollid information on the net. And well I'm no engineer, nor do I have any experience designing cars or even parts
for cars. Although I'm working on both. I'm a mechanic who works a lot with metal, hydraulics and electronics but not an expert on any
field. And won't claim that I am either.
But I believe in doing things right, certainly when it comes to suspension etc. And therefor it's always nice to obtain some knowledge from
someone who has been there and actually knows a thing or 2 about it.
So might I ask you, and others offcourse, to atleast supply the TS with the info he needs. Preferably with some sort of fundation, as there is way to
much bogus info out there. If besides that you feel the need to burn anyone who gives a wrong answer... well have fun...
out of interest, for a coil over mounted inboard with rocker arms, what would be the optimum, 45 degrees?
[Edited on 6/6/11 by mrwibble]