dampers auto - Bos Engineering Suspensions

User handbook
standard adjustments
DAMPERS
AUTO
CR
CONTENTS
Introduction
Mounting instructions
Dampers Evo1
Dampers Evo2
Dampers Evo3/CR40
How to setup your dampers?
Maintenance / Inspection
Your dampers
Introduction
BOS Engineering thanks and congratulates you on your choice of dampers for
your competition car.
Your new BOS high performance dampers are developed from our years of
experience in official championship, on all type of surface thanks to our successful co-operation with winning. Our success and results gained in few
years show the full and the exclusive implication of BOS Engineering in the
research of performance.
The BOS dampers you just bought are especially developed for your car and
your type of race. The choice of our technical solutions, the quality of our materials, the precision and the care brought to the assembly operations allow
your new BOS dampers to be an absolute weapon to win.
You will find in this user guide all the information needed to get the best of
your BOS dampers in term of mounting, setup or maintenance. This hand
book talks about lots of subjects for which a private or professional pilot can
be confronted to setup his set of damper.
We wish you a good reading and hope this document will guide you in your
life of pilot...
Note : BOS Engineering never stop to increase the range of product in terms
of design and quality. Therefore, while this user guide contains the main information and pictures of products, there may be minor differences between
this guide and your BOS dampers.
Mounting instruction
Your new BOS dampers are designed to change your old ones or the standard
road dampers of your car. Note the different point to check when mounting:
1) Remove the standard dampers
See your car’s work shop manual if necessary.
2) Mounting of the BOS dampers
Depending the type of car, your BOS dampers are designed with eyelet bearing / bearing or cartridge + strut. In every case, the mounting procedure is
the opposition of the remote procedure. If some modification are required,
your contact in BOS or you local authorized distributor will inform you in advance and guide you.
3) Top mounting
Depending the division of the car, the regulation allows you or not to keep the
original fitting points (see more detail in your car homologation document).
The top mount is fitted on bearing (specific solid top mount) or same than
original (silent bloc). In any case, ask advice to your contact in BOS or you
local authorized distributor
4) Fitting of the reservoir body
Depending the type of damper, the reservoir body must be fitted (for front
and rear) on the wheel arch or inside the car (engine compartment or rear
tank). In any case, clamp the reservoir body and keep accessibility for adjustment. BOS purpose in option some universal fitting support for an optimal
clamp. (ask us)
5) Setting up your car
Depending your vehicle and your division, the setup of your chassis can be
different. The setup of the car must be adapted to the track surface, the grip
conditions and the pilot. The next pages give you some indications on the
standard adjustment of a car type 2 WD.
• Ride height
Generally, the ride height must be low by keeping the damper stokes (in the
respect of the race regulation).
The chassis of the car must lower at the front than the rear to keep a weight
distribution to the front of the car. The ride height can generally be setting with
the spring pre-load nut or the position of the rear torsion bar.
• Camber
To increase the surface of the contact between the tyre and the ground, the
camber must be negative on a rally / racing car. This value should be close
to -2° / -2.5°
• Toe
A rigid and well suspended car is a safe car easy to drive which accept this
settings :
- Front : between zero to slight toe-in to give sensibility in the steering wheel.
- Rear : slight toe-in for stability.
Generally, if you need to setup your front and rear axle with toe-out, it means
that your car has got a bad equilibre or bad suspensions
• Caster
To have a auto-centering point effect and a better feeling of the front wheels, the setup must tend to get a maximum of positive caster (in the maximum of the regulation
or the adjustment possibility). This value is between +3° and +6° depending steering
wheel assistance or not.
Note : all these informations are standard advices adjustments. Your car can may not accept these
generality. For particular advices, contact your BOS contact or your local authorized distributor.
EVO1 dampers
Technical specifications
Mono-tube hydraulic damper with shim stacks
Full disassembly and re-build possibility
Hydraulic graphs adjustable, pre-setting at the factory depending car and running condition
Remote reservoir body with piston mounted on flexible hose
Cylinder in calibrated steel, anti-friction treatment
Rod �16 mm made in chrome steel
Configurations:
• Bearing / bearing (generally for rear suspensions)
• Cartridge + strut in calibrated steel, anti-corrosion treatment
Adjustment of the coefficient
This range of dampers comes from the family of the one way dampers with one
adjustment.
This adjustment called coefficient modify the bump (entrance of the rod) and rebound (exit of the rod) in the same proportion. In fact, the damper becomes softer
or harder depending the adjustment.
WARNING
The reference (0) for the adjustment (or clicks) of the dampers is the
position full tight (clockwise). Count the number of clicks from this position, then unscrew. More the adjustment is unscrewed and more the
damper is soft, its hydraulic force gets lower at a given velocity . The total number of
clicks is often 24 but can vary plus or less depending type of dampers, or for a same
model, depending type of car.
Different type of coefficient adjustment
1
2
Picture 1 : adjustment with screw CHC on strut
Picture 2 : adjustment with screw on eyelet / bearing
Influence of adjustments on a Evo1 / CR20
force
bump
rebound
velocity
original graph
influence of adjustment of the coefficient
EVO2 dampers
Technical specifications
Mono-tube hydraulic damper with shim stacks
Full disassembly and re-build possibility
Hydraulic graphs adjustable, pre-setting at the factory depending car and running condition
Remote reservoir body with piston mounted on flexible hose
Cylinder in calibrated steel, anti-friction treatment
Rod �16 mm made in chrome steel
Configurations :
Bearing / bearing (generally for rear suspensions)
Cartridge + strut in calibrated steel, anti-corrosion treatment
Adjustment of bump and rebound
This range of dampers comes from the family of the 2 ways dampers
with 2 adjustments.
Bump adjustment:
This adjustment setup the bump of the dampers (entrance of the rod)
Rebound adjustment:
This adjustment setup the rebound of the dampers (exit of the rod)
WARNING
The reference (0) for the adjustment (or clicks) of the dampers is the
position full tight (clockwise). Count the number of clicks from this position, then unscrew. More the adjustment is unscrewed and more the
damper is soft, its hydraulic force gets lower at a given velocity . The total number of
clicks is often 24 but can vary plus or less depending type of dampers, or for a same
model, depending type of car.
Different type of bump and rebound adjustments
Picture 1 :
adjustment of rebound with
screw CHC on strut
1
2
Picture 2 :
adjustment of rebound with
knob on strut
Picture 3 :
adjustment of rebound with
screw on eyelet / bearing
Picture 4 :
adjustment of bump with
screw on reservoir body
3
4
Influence of adjustments on an Evo2 / CR30
force
bump
rebound
velocity
original graph
influence of bump adjustment
influence of rebound adjustment
EVO3/ CR40 dampers
Technical specifications EVO 3 (CR40)
Mono-tube hydraulic damper with shim stacks
Full disassembly and re-build possibility
Hydraulic graphs adjustable, pre-setting at the factory depending car and running condition
Remote reservoir body in steel with piston mounted on flexible hose (Piggyback
reservoir body in aluminium or on flexible hose, with membrane)
Cylinder in calibrated steel, anti-friction treatment
Rod �16 mm (�18 mm) made in chrome steel
Configurations :
• Bearing / bearing (generally for rear suspensions)
• Cartridge + strut in calibrated steel, anti-corrosion treatment
Adjustment of BH & BL + rebound
This range of dampers comes from the family of the 3 ways dampers with 3
adjustments. The descriptions BL and BH mean “Bump Low” & “Bump High”,
so low speed & high speed.
Bump High speed adjustment (BH):
This adjustment setup the bump of the dampers (high speed entrance of the
rod due to a big choc for example)
Bump Low speed adjustment (BL):
This adjustment setup the bump of the dampers (low speed entrance of the rod
due to mass transfer for example)
Rebound adjustment:
This adjustment setup the rebound of the dampers (exit of the rod)
WARNING
The reference (0) for the adjustment (or clicks) of the dampers is the
position full tight (clockwise). Count the number of clicks from this position, then unscrew. More the adjustment is unscrewed and more the
damper is soft, its hydraulic force gets lower at a given velocity . The total number of
clicks is often 24 but can vary plus or less depending type of dampers, or for a same
model, depending type of car.
Different type of bump and rebound adjustments
Photo 1 :
adjustment of rebound with
screw CHC on strut
Photo 1 :
adjustment of rebound with
knob on strut
1
2
3
4
Photo 3 :
adjustment of bump BH &
BL with knob on piggy-back
reservoir body
Photo 4 :
adjustment of bump BH & BL
with knob on remote reservoir body and adjustment of
rebound with screw on eyelet
/ bearing
Influence of adjustments on an Evo2 / CR30
force
bump
rebound
velocity
original graph
influence of bump adjustment low speed (BL)
influence of rebound adjustment
influence of bump adjustment high speed (BH)
How to setup your dampers ?
Introduction
Before making your own adjustments, note that BOS recommended adjustments of
your dampers (written on reservoir of each damper) are a liable start point which
should agree to the majority of pilots in normal running condition.
But you will probably need to adjust your dampers depending weather and track
conditions. If this is the case, please read this following advises to prevent from mislaid when adjustments.
How to do when testing and making adjustments
When making adjustment, proceed by small steps one at a time of a maximum of 2
clicks, keeps notes and the results of the new adjustment. When you think to have
some good results, make the test with the previous adjustment to confirm, and then
adjust again to the new one. If the behaviour and the time confirm this new adjustment, you can valid it and note it.
Be careful to test adjustments with the same running conditions (tyres, temperature,
grip,...) and change only one adjustment at a time.
Explanations of hydraulic adjustments
Generally, all the effect of stability and response of the car are managed by the bump,
while the rebound affects the traction and driving comfort.
If your first sensation is to put the damper harder, always start to tight the bump in the
goal to keep the maximum of traction given by a relatively soft rebound adjustment.
But don’t forget to think about the setup of the chassis which is very important for
the performance of the car.
Recommended solutions
Now tackle some particular points of the behaviour of the car which can be plus or
less modified by the hydraulic of the dampers. This advises have not the pretension
to be a miracle solution to solve a problem but ways to adjust to solve a known
problem.
IMPORTANT NOTE! The recommended adjustments of your BOS dampers
always start from the position full screw which is the harder adjustment for the bump
and the rebound.
H
Adjustments :
Unscrew the adjustment gets it softer
Screw the adjustment gets is harder
S
The indications BL and BH means “Bump Low” and “Bump
Hard”, so bump low speed and bump high speed.
<< H : hard (screw) / S : soft (unscrew) >>
•
S (x)
H (x)
Glossary >>
Do not change the adjustment
Softer of x clicks, so unscrew of x clicks
Harder of x clicks, so screw of x clicks
Solution to... bottoming
EVO1
EVO2
coefficient
bump
EVO3 / CR 40
rebound
bump H
bump L
rebound
F
R
F
R
F
R
F
R
F
R
F
R
H (4)
H (4)
H (4)
H (4)
•
•
H (4)
H (4)
H (2)
H (2)
•
•
Solution to... pumping / dribbling
EVO1
EVO2
coefficient
bump
EVO3 / CR 40
rebound
bump H
bump L
rebound
F
R
F
R
F
R
F
R
F
R
F
R
H (3)
H (3)
H (2)
H (2)
H (2)
H (2)
H (3)
H (3)
H (2)
H (2)
H (2)
H (2)
Solution to... car sharp when decelerate
EVO1
EVO2
coefficient
bump
EVO3 / CR 40
rebound
bump H
bump L
rebound
F
R
F
R
F
R
F
R
F
R
F
R
•
H (2)
•
•
•
H (4)
•
•
•
•
•
H (4)
Solution to... bad traction in longitudinal
EVO1
EVO2
coefficient
bump
EVO3 / CR 40
rebound
bump H
bump L
rebound
F
R
F
R
F
R
F
R
F
R
F
R
S (4)
S (4)
S (2)
S (2)
S (2)
S (2)
•
•
S (3)
S (3)
S (2)
S (2)
Solution to... corner entry understeer
EVO1
EVO2
coefficient
bump
EVO3 / CR 40
rebound
bump H
bump L
rebound
F
R
F
R
F
R
F
R
F
R
F
R
•
S (2)
S (2)
•
•
S (3)
•
•
S (2)
•
•
S (3)
Solution to... corner exit understeer
EVO1
EVO2
coefficient
bump
EVO3 / CR 40
rebound
bump H
bump L
rebound
F
R
F
R
F
R
F
R
F
R
F
R
S (2)
•
S (2)
•
•
•
•
•
S (2)
•
•
•
Solution to... corner entry oversteer
EVO1
EVO2
coefficient
bump
EVO3 / CR 40
rebound
bump H
bump L
rebound
F
R
F
R
F
R
F
R
F
R
F
R
•
H (3)
H (2)
•
•
H (2)
•
•
H (2)
•
•
H (2)
Maintenance & Inspection
After every rally / race:
wash externally your dampers with a non aggressive
and non alkaline product, dry it and spay it with a
soft and lubricate solver (type WD40).
Every 300 – 500 km:
Remove the dampers from the car, wash it and clean
it then send it to BOS Engineering or your local authorized distributor for a Rebuild n°1.
Once a year:
Remove the dampers from the car, wash it and clean
it then send it to BOS Engineering or your local authorized distributor for a Rebuild n°2.
Your dampers
This page is dedicated to the technical specification of your BOS dampers
like the general information and the recommended adjustments.
Your will also find the serial number of your dampers which must always
be given to when you are in contact with BOS Engineering or your local
authorized distributor.
ZA du Mont Blanc
18, rue Maurice Caunes
31200 Toulouse • France
T : + 33 (0) 534 25 33 66
F : + 33 (0) 534 25 33 60
bos@bos-engineering.com
www.bos-engineering.com