F1technical.net

Hi,

I would like to know the advantages of pushrod suspension over conventional suspension system where shock absorber are installed between the spindle/wishbone and chassis

Omg you should just search around here there are tons of posts about that.

In short, advantage of inboard dampers:
-they are out of the airstream therefore drag is reduced and airflow is "cleaner"
-you can modify motion ratio/spring ratio with the rocker
- in case of pull rod activation you can lower the centre of gravity

Disadvantage:
-access to the dampers/springs can be more difficult

At least as far as F1 is concerned, the decreased drag/turbulence is their primary motivation.

Thanks mate for replying,I just asked this question as I was comparing it with conventional suspension system
also how much successful it can be on a off roader vehicle? e.g. BAJA? ATV

just think what is achievable in terms of wheeltravel over damper travel....without any leverage /lever advantage you will end up with :digressive wheelrate with all other systems and or poor leverage = small damper travel for in reference to wheel travel.So with very small wheel vertical mo´vements you quickly arrive at almost nil damper travel...not good for control.
you will inevitably have your suspension in areas of high aero importance as well...
on the other hand lots of joints and levers will add up to a considerable give and maybe even backlash and open the door for friction and misalignment /bind and opens the option of progressive and linear tailor made suspension layout .

marcush. wrote:just think what is achievable in terms of wheeltravel over damper travel....without any leverage /lever advantage you will end up with :digressive wheelrate with all other systems and or poor leverage = small damper travel for in reference to wheel travel.So with very small wheel vertical mo´vements you quickly arrive at almost nil damper travel...not good for control.
you will inevitably have your suspension in areas of high aero importance as well...
on the other hand lots of joints and levers will add up to a considerable give and maybe even backlash and open the door for friction and misalignment /bind and opens the option of progressive and linear tailor made suspension layout .

thanks for your reply,but if you consider the front suspension layout of an ATV,which has double wishbone,you installed pushrod suspension on? where you can control the ride height(by adjusting the rod position on the lever/clamp) and stiffness of the ride by changing the position of the suspension on the same lever/clamp isnt it? I guess it gives u the versatlity of adjusting both the ride height and the stiffness that you want,isnt it? correct me if wrong

nathauto wrote:

marcush. wrote:just think what is achievable in terms of wheeltravel over damper travel....without any leverage /lever advantage you will end up with :digressive wheelrate with all other systems and or poor leverage = small damper travel for in reference to wheel travel.So with very small wheel vertical mo´vements you quickly arrive at almost nil damper travel...not good for control.
you will inevitably have your suspension in areas of high aero importance as well...
on the other hand lots of joints and levers will add up to a considerable give and maybe even backlash and open the door for friction and misalignment /bind and opens the option of progressive and linear tailor made suspension layout .

thanks for your reply,but if you consider the front suspension layout of an ATV,which has double wishbone,you installed pushrod suspension on? where you can control the ride height(by adjusting the rod position on the lever/clamp) and stiffness of the ride by changing the position of the suspension on the same lever/clamp isnt it? I guess it gives u the versatlity of adjusting both the ride height and the stiffness that you want,isnt it? correct me if wrong

still there is no way to have progression with such a layout .you either need progressive springs or springstacks or whatever
and of course an atv HAS suspension travel galore .so mechanical advantage is not strictly necessary .

marcush. wrote:

nathauto wrote:

marcush. wrote:just think what is achievable in terms of wheeltravel over damper travel....without any leverage /lever advantage you will end up with :digressive wheelrate with all other systems and or poor leverage = small damper travel for in reference to wheel travel.So with very small wheel vertical mo´vements you quickly arrive at almost nil damper travel...not good for control.
you will inevitably have your suspension in areas of high aero importance as well...
on the other hand lots of joints and levers will add up to a considerable give and maybe even backlash and open the door for friction and misalignment /bind and opens the option of progressive and linear tailor made suspension layout .

thanks for your reply,but if you consider the front suspension layout of an ATV,which has double wishbone,you installed pushrod suspension on? where you can control the ride height(by adjusting the rod position on the lever/clamp) and stiffness of the ride by changing the position of the suspension on the same lever/clamp isnt it? I guess it gives u the versatlity of adjusting both the ride height and the stiffness that you want,isnt it? correct me if wrong

still there is no way to have progression with such a layout .you either need progressive springs or springstacks or whatever
and of course an atv HAS suspension travel galore .so mechanical advantage is not strictly necessary .

Well I get what you are tying to say! I will put up a picture of what am trying to convey

Aero advantages of better positioning and availability of rising rate ratios to suit large downforce. There are some situations where the push/pullrod can be mounted closer to the upright or even on the upright.

Other than that there is no advantage in this era of damper and spring technology and there are some disadvantages, namely component count.

Oh, but of course then there's that other outstanding advantage - "bling".

Another disadvantage is increased friction caused by the increased amount of bearings under high loads.

cheapracer wrote:Aero advantages of better positioning and availability of rising rate ratios to suit large downforce. There are some situations where the push/pullrod can be mounted closer to the upright or even on the upright.

Other than that there is no advantage in this era of damper and spring technology and there are some disadvantages, namely component count.

Oh, but of course then there's that other outstanding advantage - "bling".

Not so much with an ATV, but a push/pull rod remotes the damper from the brake. Dampers don't like heat.

marcush. wrote:


still there is no way to have progression with such a layout .you either need progressive springs or springstacks or whatever
and of course an atv HAS suspension travel galore .so mechanical advantage is not strictly necessary .

You can still get a rising rate suspension without a push rod. It all depends on your shock mounting positions.

For the type of vehicle you describe I would not go for push/pull. Weight and reliability reasons first. Maintenance and compliance, second. Plus, you can have plenty of suspension adjustability with 3 positions in the wishbone + 3 in the chaassis.

I agree with Belatti, compliance with bellcranks is certainly more of an issue than a direct mount. Also you will invariably run into wildly varying motion ratios due to the high wheel travel, which causes large bellcrank angle changes unless your motion ratio is low.

but sure dampers do transform motion anergy into heat as well so you need to get themn into the airstream or find other ways to release the heat-in a offroad application -

I´d think you need very good reasons to justify going that route, I´m not sure if it really cries friction and loss of installation stiffness .Of course ..if you do it with a single shear tiny bearing rocker ....that´s true ..but ther eare alot of other possibilities with no installation stiffness issues at all.