Freestyle Pushrod Front Suspension Conversion

[Tonycaterham]

 

Anyone who subscribes to LF will have received the Freestyle flyer.

 

In addition to engine mods was looking at uprating my suspension over the winter and was therefore intrigued with the Pushrod Front Suspension conversion.

 

Given the many suspension gurus out there I expected to see a whole host of postings, so has anyone any comments good/bad/indifferent?

 

 

Regards

 

 

Tony

[Colin Grundy]

Tony

If you look back through the topics of the last 10 days you will find much has been written about this exciting new development. However Len Unwin responded and claimed that this particular mod, although still in the development stage would be available apporx. March 03.

Price is as yet to be confirmed, but I think the figure of around £1500 has been mooted. Looks a tasty piece of kit though.

Sorry to be so vague, but a quick flick through the archives will tell you every thing you need to know.

[tiddy1]

Having seen many pictures of the new pushrod design all I can say is that it seems to have all the disadvantages( i.e very heavy, raises the c of g, wear problems ) but none of the advantages . the system seemed to use standard dampers and springs.

 

My understanding of in board, push rod designs is that you can increase the damper travel and so make them more efective, asa damper has to move to work.

 

The only advantage seems to be removing th eshock from the air stream but since 7s are as aerodynamic as a breeze block this will have little effect.

 

and I can't believe that the whole system is mounted on the header tank bolt!!!

 

Simon

[edmandsd]

I like Freestyle's approach to aftermarket tuning generally but don't believe the in board suspension set up is rocket science. Interestingly when HTR were building my car Ray Addis said that there was room for an in board suspension set up if I wanted it, but I wasn't too fussed at the time and wanted to concentrate on other areas of the car. That said having in board pushrod suspension must be advantageous because it's what all the top race cars use - I doubt that moving the shock out of the airflow on a Caterham would add much benefit though in terms of aerodynamics.

 

Home of BDR700

[V7 SLR]

Tiddy, where can I see pictures of the inboard setup? I've only seen the Freestyle pictures so far which don't show the engine-bay/shocks.

 

I believe this suspension setup will finally mean a Caterham can have dampers that actually do something - there will be a 1:1 wheel movement to damper travel. As my dampers appear to only move an inch either way, I'm not convinced that they're doing much for the car.

 

Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours

 

[DanB]

I think there are 4 main advantages to the Freestyle system although I haven't seen any detailed pictures of it.

 

1. Aero gains - I remember hearing that one of the best ways of improving the aerodynamics of a seven was moving the dampers inboard. Can't remember where, so this may be pubtalk folklore. However, it makes sense to me - without the dampers the suspension arms and trackrods won't amount to much of a hindrance to airflow - lobbing a 45 degree damper in there certainly will.

 

2. Spring rate - the spring rate on an outboard setup is a falling rate as the spring compresses. This is the opposite of what you need, as the car gets softer in roll rather than stiffer. Using appropriate bellcranks means you can change this to a linear or rising rate.

 

3. Increase damper travel - the inclined dampers on the seven mean that the damper moves less than the wheel as V7 has said. To make the dampers more effective a 1:1 (or even higher) ratio can be achieved, again by appropriate sizing of the arms of the bellcranks. A very ingenious system is used on the newer Radicals to achieve this end.

 

4. Looks reet tarty

 

Overall, I'd say that unless its a complete dog's dinner (and given freestyle's reputation I think this is pretty unlikely) then the inboard set-up will produce a better performing suspension set-up. Whether it's worth 1500 notes is another question which probably depends on the size of an individual's wallet.

 

Dan

Fury Blackbird - inboard suspension as standard *tongue* *tongue*

[scooby dooby doo]

there's some pics on the cam7 server...

 

 

here

here

here

 

HOOPY 500 kg R706KGU

[Peter Carmichael]

Just wondering whether the radiator exit air and heat soak under the bonnet are that good for dampers. I know that when Nitron were dynoing my dampers they cycled them up to 30 degrees before testing began. If the dampers went out of temperature range (not very far at all) then the dyno test was considered null.

[V7 SLR]

Bloody hell, that's a clever design.

 

Hoopy, I note that only once side is setup. Why is that? Where do the piccies come from?

 

Does the nose still fit over this? Could use some more pics from different angles.

 

I want one more than ever now.

 

Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours

 

[scooby dooby doo]

the nose fits, one side only as they lost one of the prototype wishbones. i got somebody on BC to mail them to me then i uploaded them. he took them at the festival - can't remember who...

 

HOOPY 500 kg R706KGU

[V7 SLR]

I confess, I rather like the idea of their packaged trackday or race "conventional" setup as a way to getting rid of the Bilsteins "relatively cheaply" and get adjustable dampers to boot. BUT if the whole package of inboard suspension, new wishbones and rose joints (wherever possible) in conjunction with new rear dampers was affordable with one year's budget... then I'm game.

 

If not, then it would be good if there could be a "staged" evolution to the full package. For example, if I bought the trackday dampers and fully adjustable ARBs (not sure I'd need the rear one), would they be compatible with the inboard setup if I upgraded to that later?

 

I'd like to try your setup Hoopy. I know it couldn't possibly be an accurate comparison as my car runs different tyres and wheel sizes etc... but if we could play with the damper settings at one of next year's tracks (on the tour) to show me the differences, that'd be really cool and would cement the idea in my head.

 

Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours

 

[tiddy1]

As you can see from the pictures the inboard shocks are almost at the same angle and size as the normal ones, there is therfore little advantage in the lever ratio so the damper movement will be no greater than the normal set up,

 

Its hard to tell what the rocker ratios are so its hard to tell. but I will be surprised if the benifits in aero are worth the extra weight, it looks as though it would weigh about 10lb ??

 

I don't want to knock the system as I have not tried it, and it is a cleaver compromise as it can be installed without chassis mods. (hence bolting to the header tank bolt) but I just can't see the point

 

Simon

[scooby dooby doo]

But its still fundamentally rising instead of falling rate. And thats a first prototype so its a little harsh to judge it as it stands.

 

Nig - I should have similar power and almost similar typre sizes on the next tour (185 and 205 rear) so should be nice to play with it

 

HOOPY 500 kg R706KGU

[V7 SLR]

Tiddy, the angle and size of the dampers has nothing to do with the damper movement with respect to wheel movement once you have a bell crank in place. It becomes all to do with the bell crank and it's leverage. This setup appears to ensure the damper will move considerably more than it does with the current (original) setup.

 

The aero part of this isn't the point of this exercise. If the inboard setup can be fitted more economically using your existing wishbones, then all the better. Comes back to my "staged" upgrades to suit my staged finances.

 

I'm not sure "compromise" is the right word. I believe the current (original) setup is seriously compromised WRT the damper travel which is severely limited on mine. Factor into the equation that the standard Bilsteins are pretty hopeless anyway and it all starts to look reasonably worthwhile.

 

FWIW the Striker has had inboard suspension from the outset, and it's hard to argue with the fact that they're pretty good track cars.

 

Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours

 

[Peter Carmichael]

Standard Bilsteins are far from hopeless. They are valved a bit strangely, but they are quality dampers with low friction and very repeatable characteristics. It is possible to punt a Seven around Curborough, for instance, very briskly on standard Bilsteins.

[edmandsd]

I always think twice about supposed improvements that add weight - The improvement would therefore have to be better to the extent that it more than makes up for any weight penalty. Difficult to determine I appreciate but something that's more relevant to a Caterham than a saloon car.

 

Home of BDR700

[Swiss_Tony]

I just re-read the booklet to confirm. It says its a 1:1 wheel/damper ratio.

 

Isnt the post 97 Caterham front suspension a rising rate setup?

 

James

 

[Lawrence_Z]

Additonal gains (ie in addition to the 3 from DanB higher up the page) are that this set up will allow :-

 

1/ Ability to alter ride height without altering preload on dampers

 

2/ Easier, and quicker adjustment of camber

 

3/ Reduction in unsprung weight

 

4/ Change to Wide Track is included

 

5/ and Len has hinted that lighter dampers may be available

 

Lawrence

ps the photographs were from Steve Foster

[scooby dooby doo]

its still falling rate - as the wheel goes up the damper goes more horizontal ie it has less movement per unit rise in the wheel, so falling rate.

 

How is camber change made easier 🤔

 

HOOPY 500 kg R706KGU

[Graham Perry]

Anyone know where and how the antiroll bar fits ?

[stevefoster]

Hoopy,

My pics I think.

 

Only one side done according to Len at the festival as he wanted to demo the old vs the new side.

 

The damper does seem to work over a much great length of its travel. You could see that if you bounced the car. I guess the old damper set up damper may have been set a little stiff and the new one soft, to emphasise the action. You could work it out with a bit of maths if you had the measurements.

 

/Steve

 

My racing pics, 7 DIY, race prep. Updated often here

Photo's of the year here

Hants (North) and Berkshire Area club site here

 

[Peter Carmichael]

The one side only was because they, ahem, lost one of the prototype wishbones. But the side by side demo was very effective.

 

Not convinced that there is less unsprung weight. In fact, the faster moving damper piston will contribute to unsprung weight as well as the push rod.

[MikeE]

Re unsprung weight that was my thought exactly. Surely all the usual unsprung components are still there (or are they lighter) but you now also have the weight of the new pushrod????

[Graham Perry]

Can we use the term unsprung anymore to include the weight of the spring ? (I had always assumed we included the weight of the spring with the conventional set up) By having the bellcrank attached to the Chassis, does the Spring now becomes part of chassis and the bellcrank becomes the outermost pivot point on the chassis ? Shouldn't we now be considering anything outside of the bellcrank as being 'unsprung' . I must admit though I am having trouble visualising it all without having seen it up close. Regardless weight has been moved towards the centreline so that must be good although the springs must have a higher C of G.

 

Edited by - Graham Perry on 11 Dec 2002 15:04:42

[Graham Sewell]

The unsprung component is the sum of the parts that have their weight supported by the ground and not by the spring. The point being that this represents the mass that needs to follow the undulations in the road surface while the 'sprung' chassis floats in mid air. Therefore, although the bell-crank my be sprung, it is just transmitting the forces from the unsprung component.

 

Sorry if my terminology is not perfect, but that is the best way that I can describe what I am thinking.

 

Cheers,

 

Graham

 

Low tech luddite - xflow and proud!