Indy Car IRS Single Spring

average guy

where do i locate the spring between the upright and
the main space frame?
this is '63 era technology build. first rear engine American mades
like Mickey Thompson cars.
can't quite get a good look at rear suspension in most of pic's.
in the front i can go right down the middle but
in rear the drive axles are in the way.

Have A Nice Day!

Attached Thumbnails

 

mender

If you look closely you'll see the coilover mounted on the inner upper suspension pivot and the lower pivot on the upright. The farther out on the bottom of the upright, the more direct motion ratio you get. However, the more angle away from perpendicular the less motion ratio you get.

Front should be very similar but inside the arms.

average guy

bender
i'll have to back pedal here.
i would like to take advantage of progress.
http://www.aaim1.com/pdfs/anatomy.pdf
it will be double wishbone like this current car.
a arms will be mounted to frame square not like this diagram.
how do i apply single spring to this?

Have A Nice Day!

slideways

You want to do a mono-shock design? Do you mean a sliding shuttle design as was used on some cars in the 90s? In general, unless you are racing a FV you probably don't want to do a mono spring setup.
Perhaps some more information is needed here.

Ranger Mike

the evelution of Indy suspensions stems from the requirement to narrow up the " car body" and lighten the weight as much as possible to the point where we spring / shock is now mounted inboard and runs through the bell crank via push rod. The major draw back to this design FOR THE STREET is the fact that this suspension is VERY twitchy.

These setups run very high spring rates, have very limited travel and are damn near like a go cart set up as they are sprung so tight. These set ups pound the heck out of the suspension parts and are very hard on t he rod ends.
I would even say this design is flat out dangerous for the street. You have no room for error and the set up it totally no forgiving. When you have the earlier double wishbone set up with the shocks mounted inboard to the top wish bone and the bottom to the frame,it is a lot more forgiving. And a lot softer on the ride. I can not over stress the input form my drivers ( 30 plus years of seat time and many road course championships) the push rod set up is flat out no forgiving regarding drive input. No room for mistakes.

slideways

I see no reason why pushrods and bell cranks can't work just fine for the street. A number of road cars use the setup. It's not common because it's expensive and the aero benefits are rather limited in a car with fenders. It also doesn't always package that well.

average guy

slideways
the mechanical engineering part is done.
the spring goes from bottom of upright to
top of frame at roughly 45 degree angle.
i was just concerned with loading upright unevenly.
i guess if it's rigid enough that's a non-issue.
i think building it to carry load of double a arms and
axle carriers will as a side benefit make it strong
enough for spring mount.
in plain language i'm not going to beef it up anymore than that
for spring.

Have A Nice Day!

mender

One way to do it:
http://www.cardomain.com/ride/336004...aren-f1/page-4

If the suspension/upright can't handle the asymmetrical loading it's not strong enough to handle the braking load.

average guy

ranger mike & mender
mike didn't see your last post until now.
no street here. no bellcrank inboard springs.
mender
we're good for now.

Have A Nice Day!

slideways

It appears the question was answered but as a general tip, the guys on the Apexspeed forum can be very good when it comes to these sort of questions. Apexspeed is a forum specifically talking about open wheel, amateur formula cars. There are several members there who have built their own cars. Additionally some of the manufactures such as Stohr and several of the F1000 designers post and answer questions.

(No, I don't have any financial ties to Apexspeed and I didn't join the forum to spam it. With that out of the way, I am Higerian Roialty. Send me banke numbrs I send you sister princes OK?)

Here are a few threads with a few good pictures
http://www.apexspeed.com/forums/showthread.php?t=22161
http://seanmaisey.blogspot.com/searc...max-results=50 - lots of pictures as he restores a car.
http://www.apexspeed.com/forums/showthread.php?t=25227 - a fair number of pictures but many were removed a few years after the fact (?)

average guy

slideways
the whole idea is to build something that
most people can build in their garage.
this car uses mild steel and is arc welded together.
1" square .063 wall tubing.
in place of bends the tubing is cut at 45 degree angles.
a Popular Mechanics type project.
more building per dollar.

Have A Nice Day!

slideways

You might ask some of the guys over there. Many did build their cars in garages at home. Not all but many. Many would have good ideas how to make an easier to weld frame.

average guy

slideways
Popular Mechanics doesn't have a forum.
it may look like forum but i believe the answers
are provided by them.
enough about that.
i think the forum members here are much brighter
than magazine writers.

Have A Nice Day!

slideways

Popular Mechanics?

Oh, sorry I see, no I was talking about asking the Apexspeed guys, not PM. I can see how that wasn't clear in the post but that is what I meant.

mender

Send money first, then princes.

Ranger Mike

i have been on APEXspeed for 10 years...good info source
as long as you know pitfalls of pushrod suspensions ..go for it..it is a bear on wear though..

average guy

ranger mike
i guess you could call it 'pushrod' suspension.
it's a little distracting with 'pushrods' for engines.
yeah i know no pushrods in those engines.
it's really a bellcrank mechanism.
it's also grossly overloading the small bellcrank
from a classic engineering viewpoint.
the metallurgy let's them get by with it.
anyhow that's for somebody else, not me.
i'm just playing Jim Hall here.

Have A Nice Day!