Hot Rods **FOOSE P-32 Roadster >> Have you Studied the Steering??**

I just found the steering for my next roadster project.... now if I could hust find a reasonable 26 or 7 roadster body

 

Ackerman can be created with the bellcranks, by moving the pivots.

 

Unk ...I was talking about the steering in the MG that 251 garage posted. Basically it is a cowl steering with a gear to drive the passenger side.

I guess I was getting off topic but it sorta goes in the same direction as Foose's set up.
Clark

 

Nice to see some dings in the oilpan, and blow by and grease on the chassis.

 

Neat post!

 

Yep! I believe that would be correct... Haven't tried it yet, though.

 

You are correct. I didn't notice that until you pointed it out. Another picture shows that the Golden Sub had a steering box with Pitman arms on each side of the car like the MG setup mentioned elsewhere in this thread. Chip's setup is ingenious!

 

Okay, it's Friday and I felt like doing something irresponsible... So I actually took a few minutes and messed with the bell crank ratios to adjust the Ackermann. For those of you who aren't familiar with the Ackermann theory, here's a short bit about it:

http://en.wikipedia.org/wiki/Ackermann_steering_geometry

To change the Ackermann I changed the distance of the mounting positions of each link on each bell crank as well as the angles in-between mounting positions. IT'S STILL NOT CORRECT, (instantaneous center/center of turning circle is in the wrong place) but it's closer and would just take a little more messing with the bell cranks, their position, and the lengths of the connecting rods to get the correct ratio for the wheel base of the car and track width. Just wanted to show this for reference. Again, hopefully this will help explain how it all works, though.

 

Holy crap, Scott! That rules... Your drawings actually make this seem 'doable' now

 

Okay, I spent a little more time studying. This just about puts it in the ball park. Changed link distances from the pivot point of the bell cranks so they're all equal and changed the interior angle so it points at what would be the 3rd member. Seems like this should work. Anyone want to build one and see??

For anyone that would actually want to DO this, everything would depend on wheel base, track width, steering box, pitman arm length, etc. Basically, it seems like it's all about the design/geometry of the bell cranks and their position in the chassis to achieve the correct Ackermann.

Seems the bell crank dimensions from pivot to the link centers should probably be increased for actual drive-ability, but this at least proves out the geometry.

Mostly just thinking out loud. Maybe someone with more suspension design experience can confirm the theory...

 

scootermcrad - I always had a feeling that we had met before ... and sure enough, here's a pic I took of you @ the "Magoo/Burnham - Hot Rod Heroes Roast" in January of '91:

 

If the action of the drag link simply duplicated the movements of the bell crank and spindle directly the position of the cross-link assembly in the car becomes immaterial. Think of it: the motion is the same regardless of how long the drag links are. You'd set up Ackermann based on what the steering arm angles would have been at the spindles, and just transfer the geometry as is to wherever the cross-link assembly is: could you test that, scootermcrad?

I've been looking at something similar for my '31 project, but with a few differences. My steering would be by a rack and pinion mounted on the firewall, over the driveline. The bell-cranks would incorporate vertical shafts to bring the movement to the correct height. Importantly, because the ends of the lower cranks poke out under the frame rails the drag links would be outside the frame rails in their entirety, and would therefore be pretty much parallel to one another. Here's a quick drawing:


The main advantage is packaging: one no longer has to ensure that there is room for a tie rod to move through all steering and suspension movements, but this also works well with the concentric/rotary-articulated tube axle arrangement I've been moving to, where a fixed-length tie rod would induce a tiny amount of bump-steer.

Then, of course, it should be kept in mind that 100% Ackermann isn't always the ideal steering configuration.

 

This is an interesting thread.

 

My favorite quote in that article:

Interviewer: "What does the car look like without the windshield?"

Foose: "Looks like it needs one."

 

I'm surprised no one has scanned the article yet and i was looking through the magazine just the other day, its Street Rodder July of 2006 for those of you who want to read the whole article, sorry I have a crappy scanner. at the spindles it appears to have 60 degrees of movement, at the bellcranks it appears to have the capability of 90 degrees of movement.

Make sure to open pictures in a new window to get a full size image

 

And there we have it... Any chance you have the rest of the article scanned?

One thing I didn't do was angle the steering arms attached to the spindles. I was first thinking it wouldn't make a difference, but based on Foose's scale model, it looks like he angled them back towards the rear about 15°. Makes sense...

Thanks Hemi32! Those were my favorite jeans, also. I had another pair with ripped knees too. I only wore those around the house though.

 

Here are pages 1 and 2. not much about the actual operation of the steering.

Scooter, what version of solidworks are you using?

 

Thanks!

I'm using 2008, but I'm going to be upgrading before too long to the most recent version. I think the newer versions come standard with a few more bells and whistles.

 

Thanks alot for posting the article, Deucerails!

 

I`ve seen this done somewhere with a smaller diff in place of a Shroeder like box, and with two draglinks like the Miller.. Servicar diff or something..?

 

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 9"><meta name="Originator" content="Microsoft Word 9"><link rel="File-List" href="file:///C:/Users/BARRIN%7E1/AppData/Local/Temp/msoclip1/01/clip_filelist.xml"><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <woNotOptimizeForBrowser/> </w:WordDocument> </xml><![endif]--><style> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style> Just curious, does anyone know where the shocks are mounted? I can see what looks to be a shock link coming off the bones.

 

Great post. Thanks for the cad drawings.

 

I've been working on something similar, only using a rack-and-pinion and moving everything much closer to the front of the vehicle. That works because the upper links locating the axle are, for other reasons, quite short. This packages nicely, with the rack over the top of a short, low-mounted radiator and underneath an engine air intake through the grille:

The point is, figuring out the Ackermann requires a lot of trial and error, and I can't see a simpler way of doing it. The plus side is, there is potential here for what you might call "progressive Ackermann", i.e. more Ackermann at tight lock than otherwise, or the sort of Ackermann you need in fast corners and parking manoeuvres at small and large steering inputs, respectively.

 

some pics of my lakester

 

Foose is a true visionary that keeps reinventing the WOW factor on his builds. I love the P-32 roadster.

stewscoupe1929-neat set-up. You should do a tech thread on your idea and outcome.

 

Ya i know.. but im not good with tech articles.. i love to take pics and all but you know... it took a little bit of thinking as far as dialing the wheels in for one to to not turn father than the other.. as far as concerns is if i have any shimming in the tires from being off balance or as they call a death wobble... i dunno .. i'm curious how it will turn out and handle down the road.. im using a corvair steering box and the ratio to my steering wheel is high.. i will try to take some more pics to show the latest.. those are kinda old pics..

 

stewscoupe1929, love that frame, neat car. When I saw this thread the first time, I thought of this car The Stilletto. The steering was similar to fooses I think. The suspension folded away on this one.

 

Ned,

Here's a page scanned from (errr, I'll get back to you with book title) which explains the technicalities behind Ackermann and which angles are the important ones. Hope this is helpful.

Dominic

 

Just curious, I'm assuming (because of where we are) that this is intended to use a straight axle and wish bones. Wont moving the steering up close to the axle center and mounting it to the frame induce some bump steer due to the tie rod arc and the radius rod arcs being miss matched?

 

The axle is to be located by one long lower and two short upper links. At that stage of the development of the design I was struggling with interference between the steering linkages and the suspension interlink mechanism at lower-link level, and so tried the above arrangement with short drag links at the height of the upper links. The design has moved on; it's nowhere near finalized! If nothing else I'm proving that there's more than one way to skin a cat