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Invoard or outboard
Roscoe - 21/9/06 at 02:52 PM

Hi Guys,

This is my first post here. BAckground is I have recently moved to manila and left my project behind (mk1 escort to group 4 spec) Board and desperate for a project I am looking it importing a MNR. (help and service so far has been great)

Anyway the car will be used for weekend fun and track days. oging R1 route but should I go for inboard suspension. Does it make a noticable difference.

Also do I need an LSD as I have been quoted for a non lsd (ps I am buying complete kit [everything] as parts are hard tosource over here so I need to get my spec right upfront)

Sure this will be the first of many posts!


G.Man - 21/9/06 at 05:05 PM

LSD is great if you want to do big powerslides... so well worth it for throttle steering..

Inboard suspension is rising rate, so gives better handling than outboard suspension... definately worth it to keep the shocks protected as well...

Spend the money now and you wont regret it


peterriley2 - 21/9/06 at 05:11 PM

the inboard suspension is supposed to cut down on drag, to what extent i couldnt tell you... to be honest i reckon it'll be pretty similar to the outboard, and i guess it weighs more as there is more metal involved (depends how anal you want to be).it really boils down to a choice of what fo you think looks better- with suspension coming out, or having it all tucked away inside.
the lsd thing, if your going to get really competitive on track, its probably best to have an lsd, but th sierra ones dont work that well anyway (in comparison), and kit cars handle great on track with or without one. also keep in mind that lsd's weigh about 10kg's more than open diffs. depending on how much money you have to spend, id just say both these things only will make a small difference, and personally id keep the weight down as that will sure help with handling a lot.
hope that helps


G.Man - 21/9/06 at 05:58 PM

Peter

I think you need to read up on rising rate suspension my friend...

Inboard rising rate suspension is designed using cantilevers to increase the resistance of the suspension as it compresses further, thereby making it stiffer and allowing the use of a softer spring for short travels...

This makes the suspension compliant over small bumps, but stiff under hard braking or cornering...

It has nothing to do with reducing drag...

Outboard suspension is falling rate, due to the geometry and gets softer the more in compresses, meaning increased requirements for anti roll bars and stiffer springs thereby giving a harsher ride..


Jon Ison - 21/9/06 at 06:05 PM

I think the fact you haven't got two shocks/springs exposed in the airflow is his reasoning behind losing a bit of drag. Read "a bit" ie, a velly small bit.


G.Man - 21/9/06 at 06:11 PM

quote:
Originally posted by Jon Ison
I think the fact you haven't got two shocks/springs exposed in the airflow is his reasoning behind losing a bit of drag. Read "a bit" ie, a velly small bit.


Yeah I suppose on an F1 car it has that effect, on the front of a 7 I would imagine its negligible, as they are already as aerodynamic as an average housebrick


Jon Ison - 21/9/06 at 06:17 PM

Yea, but mines more like an breeze block......................


roadboy - 21/9/06 at 06:52 PM

The big difference is inclined outboard suspension is falling rate ( not good), inboard is rising rate ( good ), the more the suspension travels the stiffer you want it to be, giving better progressive load up. Outboard gets progessively softer both in spring rate & damper performance as it compresses.
I bought inboard
HTH Ian


pawgrp - 21/9/06 at 08:09 PM

Hi, was interested to see you're in manila. used to live there many years ago and have great memories of the place.

Have you looked at the new chassis from mk? its got inboard shocks and the chassis works well.


peterriley2 - 21/9/06 at 08:10 PM

okay i have been told!!! i actually read that bit on a site reviewing the new(ish) caterham, they said caterham told them it was partly to do with aerodynamics......


mnr laptop - 21/9/06 at 09:10 PM

biggest advantage for me is that i can run 100lb springs on the front of my racecar ( inboard ) as opposed to 300lb springs outboard which believe you me changes the whole dynamics of driving the car, you could argue it it not necessary for the road and is mainly a track tool but taking cars round the roads where we are it is immediately notiiceable the smooth ride

best regards

marc


G.Man - 22/9/06 at 04:00 AM

Marc

I already know you speak the truth, roads in cyprus are worse than UK, and the compliant ride, yet firm handling is a joy to behold..

Much rather have decent suspension than beefy anti roll bars...


nitram38 - 22/9/06 at 05:10 AM

Inboard suspensions main benefit is un-sprung weight.
If the weight of the wheel on the wishbone is lighter i.e. no shock, then the wheel is more responsive over bumps.
This means that it will spend more time in contact with the road instead of in the air.


Agriv8 - 22/9/06 at 07:12 AM

even with a v8 lump in ( or not in at this moment in time ) running 125 lb springs good for road a little soft for track.

Personally for the track id save your pennies a little longer and go for inboard.

Just out of intrest ( beacuase I dont know the answer ) does the rising rate / falling rate have much afect on the actual damper


02GF74 - 22/9/06 at 09:35 AM

quote:
Originally posted by nitram38
Inboard suspensions main benefit is un-sprung weight.



just what I was going to say.


G.Man - 22/9/06 at 10:10 AM

quote:
Originally posted by nitram38
Inboard suspensions main benefit is un-sprung weight.
If the weight of the wheel on the wishbone is lighter i.e. no shock, then the wheel is more responsive over bumps.
This means that it will spend more time in contact with the road instead of in the air.


Do you guys not understand rising rate and falling rate suspension??????

You lose very little unsprung weight going inboard as the shock is mounted to the chassis, so it is only the pushrod into the shock that is unsprung, the top of the shock is mounted on the sprung chassis, unless you have them upside down


chockymonster - 22/9/06 at 10:34 AM

On the RT+ you also get a wider front track which has to help with improved stability. Also the shock action isn't acting on the wishbone directly it's controlled by the pushrod.