Shug
Whos tried building their front suspension with inboard shocks similar to the F27 setup then? Would like to swap notes
Shug
Shug,
Bob MacLeod has kindly put complete plans for inboard shocks on Mike Polan's site:
http://members.rogers.com/7builder/Downloads/BobsShocks.html
Steve Graber designed his own setup using bike shocks:
http://www.newtier.com/graber/mid-engine/Front_Suspension_Cradle/index_2.html
Dozracing also had an inboard shock kit on his website, that was designed for a standard chassis, but it has disappeared from the online catalog. I
recommend emailing him for pictures and a quote.
Sorry if I left anyone out!
Hope this helps,
Pete
Cheers Pete, I like the pushrod version, the adjustable spring platforms are a brillant idea simply done
Shug.
quote:
Originally posted by pbura......Sorry if I left anyone out!........
lower unsprung weight (i think)
better aerodynamics (I've been told it makes quite a difference)
Looks sexy (very important!)
Alan:
Damn! 
I knew I was forgetting someone.
Some splendid workmanship on those upper shock wishbones, too 
Syd:
Advantages of inboard coilovers are:
1. Can be made to rise in rate (or remain constant) as bump increases. Springs mounted on the wishbones decrease in rate as the suspension
compresses and the shock angle increases correspondingly.
2. Forces are applied directly to the end of the shock/spring, rather than at an angle, so springing and damping is more efficient.
3. Benefits in decreased unsprung weight and wind resistance as Mike mentioned.
Keeping the shocks out of the spray is good, too!
It's a great setup, but some extra work, obviously. It's one of those things, along with a Mumford link at the rear, that I'm going to
wait and see if I feel like horsing with at that stage of the build.
Pete
Just a couple of minor corrections!
Having inboard shocks does not reduce unsprung weight! The wishbones still weight the same from chassis to wheel, plus there is a pull or push arm to
add to the equation. There is also more material that has to be accelerated up and down due to the inboard section. The shocker is still attached to
the suspension and is part of it.
It actually adds some weight overall, but it's major improvement in spring rate control more than compensates for this.
The forces through the shockers can only be direct along it's length unless it is fixed in more than one place each end. However the forces at
the mounts are more direct. Unless this is what you meant Pete?
Syd, I think your trig is rusty! It is a falling rate that a normal outboard setup gives.
Also the extra stress and forces going through the pivot is only what would be applied to the original shocker mount in an outboard setup. So actually
you are distributing the loads better across the wishbone mounts instead of into the centre between the mounts that is unsupported.
Aerodynamic forces start to come into play at anything above 30mph, so anything done to improve air flow will have an effect however minor.
Terry
just a thing that occured to me whilst pondering this one, i think that unsprung weight should maybe actually be worked out as angular momentum,
mainly because the rocker bone might balance itself if unconnected and not apparently have any weight (only mass), even though the wheel may feel
lighter it may have more mass to move.
Thinking back to the beginning, a low unsprung mass is desirable so that the wheel can respond faster to road undulations. on a standard set up it is
easy to work out unsprung mass cos its all mostly in the same place, at the centre of mass of the hub. With complex inboard setups it is easier to
calculate total mass and then work back to the actual inertia at the hub, which can be compared like for like.
For simplicity of working stuff out i would personally call the spring weight negligable compared to the hubs weight and forget it. You cant really
add on half the springs mass cos its not evenly distributed, the adapter end will be heavier cos of the seat and thread, and i guess the damper fluid
as well. On the inboard designs this end is on the car and hence is sprung, on standard designs it is on the bone and is not sprung. Whilst i
wouldn't imply this is necessarily important or enough to make a difference, it is technically true.
Sorry if that was all drivel. I personally think inboard is nicer though having read this thread i accept it doesnt really reduce unsprung mass.
Alan, Neat job on the top mounted pushrods on the upper wishbones, I take it the adjustment for the ride height is on the pushrods/locknuts.
Shug.
Impressive Drawing follows
Just an idea.
Cheers
Chris
Shug, yes correct, or even swap them out for shorter/longer ones.
Syd, my number one reason for doing it was none of the reasons mentioned....
Basically, because it is the bottom end of a McPherson strut I wanted to put the main load path in same place......through the top of the upright,
rather than loading the lower ball joint in way it was not designed.
I know many converted strut applications are bottom loaded, but I preferred not to go that way....just my choice
And, Ok it is cool too...
Chris, yes sure it would.....pretty much F1 style really...
Chris, yes I know of a car locally that uses somthing VERY similar
Alan we considered top mounting the pushrods on u know what but dont have enough space under the bodywork, at least on the front.
Shug.
Aside from the fact that it looks the business.... --- I feel the need to point out one of the major reasons that I built my inboard shocker
design.
The Hub/Upright that I used is originally McPhereson Strut. It was designed to carry loads from the top mount through the strut. The lower balljoint
was never intended to carry the weight of a car. Granted, my car may be 1,000Lbs lighter than the donor. And the lower bj may never fail when
subjected to this increased weight loading, but why take the risk?
Besides, I think the design I came up with is simple, lightweight, and allows for a great deal of adjustment. Not only height, but rate by use of
simple bellcranks. And who can argue with fully adjustable dampers (off a 2002 Yamaha R6) for only $20 each!? Yet, it's all untested. So my
mileage may vary. Time will tell won't it?
Steve. A lick of paint and it will look the mutts nutts, now if you had the wishbones in Airflow..... Aero-tube would look cool too (Jaw drop factor)
but it still looks good. Do you have an estimate of all up dry weight yet?
Shug
all true, i didnt mention i was very impressed with all the designs done. And the adjustment thing is pretty cool. Would've liked to do it myself, mebbe next time eh?!? have to get better first...
Thanks Hugh. I humbly agree. The geometry was inspired greatly by Alan B. I now have SusProg3D, but have not yet run the numbers. Too lazy...
Those Toyota uprights and brakes are way heavy! I can't remember the weight of that entire assy off the top of my head, but it would be
possible to lose 15 to 20Kg by using ali uprights and Wilwood ultralight calipers. It's all about money though. And the fact that I have so
little of it... 
I am confident that the total up weight of the car is going to be in the 600Kg range.
this is a pic of the racecar i mechanic on during the year. When we go to different circuits we change the spring rates accordingly. one way to do
this is to change the rocker ratio by moving the hole that the push rod mounts to on the rocker. This changes the wheel weights and hence the
springing. Has anyone done the calculations for the inboard suspension design on this thread for the wheel weight to see if it is equivacable to the
standard shock mounting position?
I understand the mounting angle of the shock is unimportant ie whether vertical or horizontal, but is the angle in relation to the rocker itself
something that requires consideration?
here are a couple of pics of the setup i'm familiar with:
Ned is that a hill climber?
nope, its a 'Nemesis' built by gpcmotorsport ( http://www.gpcmotorsport.com ) for the nationalsupersports series (
http://www.nationalsupersports.com )
Vauxhall 16v xe based, 230bhp spec engine on carbs. slicks, wings, carbon bits, data logging, blah, blah, blah. not quite locost!
Ned.
looks nice, must go like greased cod off a frozen shovel! The angle of the spring to the rocker will affect the spring rate if it changes leverage, and also if it is rising or falling rate as someone mentioned earlier.
Syd...no offence taken at all....all your points were valid and good questions raised........in fact you summed up my main reason quite
well..."top load the bj in a low front car"......as you say there are other ways (as per Steve for example).....healthy discussion is
good
Syd,
Here's a little music for you:
You're right!
In the traditional setup, the upward force of the wheel in bump is transformed into rotation of the wishbone about its chassis pivot. The wishbone
and shock become more perpendicular through their travel, as you pointed out. I'm glad you brought this up, because it adds support for a system
that is much simpler to build.
Still, it's possible to design the inboard system so that spring rates increase dramatically in bump. I think I would prefer that they stay
constant, myself, because changes in relative stiffness between front and rear during accelerating or braking could lead to some screwy handling.
Also agreed that overall weight will increase a few pounds with the inboard layout, but I think that a typical inboard layout will improve the
unsprung to sprung weight ratio.
Ned brought up a huge potential benefit of pushrod/pullrod systems, of being able to tune your spring rates if you have extra mounting holes in the
bellcranks.
So, as with all things Locost, you pay your money and you take your chances.
Pete
Just a small aside on this topic.
Before I bought my MR2 for a doner I was looking at many FWD cars plus the Pontiac Fiero.....had I got a Fireo (which was quite possible) then I would
have had a conventional front end as the Fiero is extremely Cortina-like......
Just shows how your design decisions can be driven by seemingly trival factors like what doner car you see in the paper first...
Interesting thread - a questions springs to mind - how do folks make that crucial hinge eg top wishbone inner on Alan B's pictures.
Bob C
PS I was a bit disconcerted by Alan B's reliance on the beam strength of 1" sq tube where the 2 dampers bolt but I note a general lack of
triangles so I guess they ain't been put in yet...
Bob, good points, which I'll try to address.
Top wishbones........ have Oilite (bronze) bushings in and pivot on a common hardened steel shaft (3/4"dia). There are shims each end to set
castor, about plus/minus 10mm is available. Some of the bracket gusseting has still to be done.
Lower shock mounts....are actually on 1.25"x 14g square...however, your point is valid and observation is correct...I have yet to triangulate
that area (and others)..need to check on a few other things before commiting to how I'll do it...
Making it up as you go along....
I like your style.
Thanks Al - hah - you answer one question & it leads to 6 more....
Oilite bushes - are they sintered bronze? Will this be a "grease point" on the final product?
I reckoned the constant heavy load on the hinge would put rubber out of the frame, though I believe the Stryker uses nylon bushes??? I suppose this is
why these suspension systems are only seen on "race" type cars with metal to metal joints everywhere (push/pull rod systems are also loading
up the wishbone hinges).
I believe the major plus with the inboard systems is the rising rate, which you can also achieve with non-linear spring winding pitch. Does anyone
flog rising rate springs that we can use?
cheers
Bob
quote:
Originally posted by Metal Hippy
Making it up as you go along....
I like your style.
quote:
Originally posted by Bob C
Thanks Al - hah - you answer one question & it leads to 6 more....
Oilite bushes - are they sintered bronze? Will this be a "grease point" on the final product?
I reckoned the constant heavy load on the hinge would put rubber out of the frame, though I believe the Stryker uses nylon bushes??? I suppose this is why these suspension systems are only seen on "race" type cars with metal to metal joints everywhere (push/pull rod systems are also loading up the wishbone hinges).
I believe the major plus with the inboard systems is the rising rate, which you can also achieve with non-linear spring winding pitch. Does anyone flog rising rate springs that we can use?
cheers
Bob
quote:
Originally posted by ned
nope, its a 'Nemesis' built by gpcmotorsport ( http://www.gpcmotorsport.com ) ...
Ned.
Evening all, best thread for ages lots to think about, but having had a look at the prosport that Ned plays with at weekends who needs a lotus 7
lookalike
Setup at the back not unlike the formula lotus we used to play with a few years ago If you see a spare gearbox from one of those lying around
Ned let me know and I will forward u my address, Thats the expensive bit Any chance of a front and side shot of the whole car with the bodywork on
?
Regards all
Shug.
[Edited on 14/11/03 by Hugh Paterson]
Shug,
Pics shortly, though we don't like being referred to as Prosports, they're radicals and we beat them easily (even with a tuned 1500 busa
lump.)
Ned.
these are from thruxton (156mph gearing IIRC) performance is quicker than British GT's, about same as ARP F3.
NO COMMENT:
[Edited on 14/11/03 by ned]
Interesting cars, not seen them before Ned, but thats what happens when you live North of Hadrians wall and dont fenture South much now
Shug.
erm, is croft too far? we've been there the last 2 years!!
Ned.
Ned, It Is when you have spent 10-16 hours a day building a car from the ground up without trying to upset SWMBO for nine months, on a 6-7 day week.
Christ you dont want her to think we enjoy this By taking a weekend off to look at SOMEONE ELSES Cars
Shug.
is that the series ccc done a feature on a few months back ned ????
dunno i'm afraid!
basically its for fully enveloping bodywork rear/mid engined prototype cars. SP1=230bhp spec vauxhall xe engine, sp2=power to weight ratio based
sp3=radical prosports.
7 double header meetings last year (14 races)
all info on regs and formula is on the site http://www.nationalsupersports.com and yes i am the webmaster though i don't get the emails....
Ned.
[Edited on 14/11/03 by ned]
err sorry to post this way down here but, the subject of inboard suspension....If I remember about unsprung weight from motorbikes the unsprung weight
is the tyre,wheel and internals(inc brakes) and the swing arm or forks up to and including half of the compression unit (spring) this can be applied
to the above.
the pictures of inboard supsension look the absolute dogs dangling bits..and could provide a method of front suspension and drive for a 4wd cosworth
install...(pulling the front diff forward onto a plate in the front area behind the coil overs..in pic......)mmmm cos I have always wondered how to
get the drive shafts past the coil-overs..how do subaru's diffs bolt on to chassis or engine..
A four wheel drive locost now I know theres another nutter in here other than me, maybe its the Scottish air
Shug.
quote:
Originally posted by malcolmstoddart
how do subaru's diffs bolt on to chassis or engine..
Audis quattros too. It's like a transaxle but with an output for the rear too and the engine is mounted ahead of the front axle.
Now Shug, you know it isn't the Scottish air we breathe, its the heather we chew...!!!
Anyway I was just thinking, a while ago I had a 4 x 4 granada (ex police) and its front dif was bolted onto the side of the alloy sump...and this is
where I was leading, using the v6 box and driveshafts etc and shift the diff forward to behind the inboard - upright coilovers and away you go...yee
haa...!!!! bet someone has done it before...
Malcolm, If u want to go down that road fill yer boots mate I have enough problems on my plate without THAT project, I already have a 4x4 dont want
another one, cant see me towing my boat with a seven anyway, as if I didnt get enough attention from traffic polis No doubt someone will build it
though
Shug.
[Edited on 15/11/03 by Hugh Paterson]
LOL, I've discovered why I'd been getting bandwith warning notices from my ISP - usually my site doesn't get this many visitors .
The link: http://members.rogers.com/7builder/Downloads/BobsShocks.html
should be back up in December, Roger's has taken it off line as I've exceeded my bandwidth capacity this month.
Mike, I was in a panic once when your service was down. As soon as it was back, I put Bob's stuff on my hard drive. Absolutely brilliant
work.
Wish I'd done the same with full dimensioned S2 drawings that were once in the Yahoo SCCA D Mod/E Mod files area
Pete
No worries Pete - free hosting means the site'l be up for a long time, just not very reliable . I know what you mean - it's even more
amazing that Bob did it with sketches and cut to fit, and that it works so nice - it wasn't till after it was working in his car (and generating
interest) that we got together to draw it up on the CAD.
Has anybody done an analysis of the chassis deflection under load for inboard vs outboard shocks? The load paths are radically different so I would expect chassis designed for stiffness in the usual planes with outboard shocks to perform strangely with inboard shocks. Any ideas?
Just to join in.
There is a retro fit inboard suspension design on my website www.gtstuning.co.uk thats very similar to how Caterham have done it on thier new car they
tested at Brands last week. Its not as elegant as i would like because i decided to make it retro fittable for a std. built car.
I quite like the pictured setup, but, my comments would be that its way way over designed, and as such not particularly aerodynamic and looks
incredibly heavy, although probably better than having the shocks all out in the breeze. Not sure the rod ended link is neccessary, i think it works
with just a plain welded in tube, which would make it lighter. With this design you could afford to use smaller tubes, or better still use aero or
flat oval tubing. Another way to concider doing it would be to make a sheeted in old race car style rocker out of it which would reduce the frontal
area of it.
Nice work, keep it up.
Darren
Darren
I can't see your inboard suspension on your website, can you post a link? thanks. ps any news on your irs wishbones/kit yet?
thanks,
Ned.