Well I'm at the stage of my build where I need some geometry settings and feedback.

Having built a couple of race cars both with live axle and independent, I don't understand why the Austin 7 does not use a pan-hard rod or similar.

My understanding is the movement on a standard rear end can invoke oversteer due to its movement.

I am intending to fit a pan hard rod to handle this.

Also I'm about to install trailing arms both back and front, when I look at most specials, the rear springs anchor the axle from effectively underneath, I then see a trailing arm being mounted as close as possible to this point? "Underneath"

This I don't understand, I unless I can understand why not intend to mount the trailing arm on the top of the axle sandwiching it between the spring and arm, this way it's held and will stay in position rather than being a "flappy tongue" out the back relying on the torque tube to maintain position.

I admit I need to dry cycle the movement to make sure the torque tube will work as designed.

Moving onto the front, I guess at this stage the castor angle should be around 5.3 degrees, now I can achieve this by varying my tubes attached to to the upper and lower stub axle mounts, I'm using a Tube Sports Axle, obviously when I pull the upper mount back, 5.3 this is about 3/4" kick from top to bottom there is no real allowance on the spring mount or the shackles to achieve this?

Camber is set via the axle and stubs, how about "tow" I'm guessing we are towing in? .5 or 1.0 degree?

Any thoughts on the above would be greatly received.

Thanks

James

James, I think you are getting bogged down with technicalities and settings before you have even started!
I would look at some of the really effective Austin 7 racing cars, they are mostly very simple and without Panhard rods or trailing arms can corner and handle at amazing speeds. The extra rods and linkages will all add weight, the best cars are those where weight has been saved.

James,

Racing cars are obviously not my area but the Austin Seven torque tube rear axle wouldn't seem to be the best place for a Panhard rod. Not sure what you mean by 'trailing arms back and front' but again with the torque tube ball joint and spring mounting there might be a problem.

Regarding 'toe in' we discussed this recently on the Forum with a range from 1/8" early to 0 late for the standard road car.

Tony.

Location: Malvern, Melbourne.

Hi James, A couple of Sketches of what you have in mind would help.
Cheers Colin

Location: Oxfordshire

Is the trailing arm you have seen not just the rear shock absorber?

Location: New Forest

I had been wondering the same thing, Stuart.

Location: Herefordshire

If your rear springs are cambered, you will have rear axle steering on cornering as already said. Not so much of a problem with flat rear springs, some extra spring clips will restrict sideways movement of the axle.

I have cambered rear springs on my '32 special and did fit both a Panhard rod and a rear anti-roll bar to deal with the latent oversteer when pressing on through corners. Obviously, this metalwork added some weight, but in my case it was more than compensated for by the vastly improved handling.If the technology works, there should be a couple of photos of the underside of my car.

Get hold of the fairly recent articles John Miles wrote about modifying his Ulster rep. Very interesting engineering exercise.

HI, Are Frank and James the same Person going on first Post from James.
If so some one is Taking the ****

Hi Colin,

Do you really think that?

James

or

Frank....lol

Thanks for all the replies so far, I have been building cars for 20 years as I said earlier, it’s always great to see replies with a truly honest post, like “are you sure it’s not the shock absorber”

I’m not being argumentative or trolling either. There are lots of ways of doing the same job sometimes, I don’t go with the flow, just because lots of people do it one way I will always try it another way.

I have been collecting 7 bits for a few years now, I had not bothered to start putting things together till I had enough parts to play with.

I’m so pleased I had collected all those springs and small bits and pieces I thought I would never use; I think I have rooted through everything in the past few months.

I’m not to concerned by the extra weigh t a panhard rod will add and a few mounts here and there, as quoted earlier these things can be made light anyway.

It is a single seater so not much body weight and it’s also supercharged on a Reliant 750 side valve. Getting it low enough at the back is also a challenge verses the sports axle at the front. I can make some lower spring hangers if necessary. But as its going to be road legal I want it to clear speed bumps.

Here's a link to my build blog page,

http://www.facebook.com/LotusSportster7/photos_stream


http://www.facebook.com/LotusSportster7

James, what a gobsmackingly excellent project. Love the idea of the engine slewed across and the prop down one side - brilliant. Have you ever driven with one of those sv Reliant gearboxes? Mine from 1956, which I drove in 1970, was a very agricultural non-synchro box - possibly strong but certainly not slick. AND NO SYNCHROMESH.

HI, James I made those comments because your first post came up as By Frank Hernandez Please Accept my Apology If that's not the case
ColinHHt87G

WOW! Seeing how you built your Cosworth Super Seven from scratch I am keen to follow your build of the Austin special.

Location: Derby

Hi James, A few ideas to put in the mix re trailing arms on rear .
Cut off the chassis just forward of the front of the springs and reposition to the outside until they are running parallel to the centre line of the car this will also mean altering the brackets on the diff,
doing this will enable you to fit a trailing arm above the spring out of the way of the drive shaft.
the trailing arm needs to be mounted about 5 to 6 inches above the bottom of the spring were it comes out of the chassis and the diff end the same height above the centre of the spring eye.
You will need adjustment on the trailing & Chassis bracket
also the drive shaft will need a universal at the diff end because it will rock the diff a small amount.
Colin

Hi Colin

Thanks for the ideas, I'm going to have a good go at it starting tonight, I also have a few ideas, At the moment the difference between the back and front is about 4" I can get the front up by 1" so that leaves around 3" to drop on the back, my springs could come down maybe 2" and by the time I'm sitting in it should be about level.

Throughout the build I have tried to maintain the 1938 authenticity of the car, By recycling as many parts as I can. As much as I have added stiffness to the chassis it is still the original shape. I will be welding in some plates on the bottom of the chassis rails to complete a box section.

I am well aware that by adding an ARB and stiffer shocks will do nothing if the chassis still twists.

I will keep the updates coming.

Cheers

James

Hi Andrew

Glad you like the project, I have not tried the gearbox on a running car so I await the first drive with anticipation!

I have a later reliant gearbox that I'm sure could be mated if it is that bad.

I'm sure the complete experience will be eye opening.

Thanks

HI JAMES

Re stiffness of chassie try fitting a full length Tophat section the same depth as the cross members also box the cross members,this gives a stiffer end result and you still have the original shape.

Colin

Now here is a man who is not at all affected by-

"DVLA New Rules which are going to affect us all"


Tony.

Location: Malvern, Melbourne.

I used a Watts Linkage when I was building my special.

What was Frank talking about? It made no sense to me.

It did to me. I should take the trouble to understand. There are some people on this forum who really know what they are talking about. Frank is one of them.

Lol. My Special has a 1960 County Council issued chassis number, and is according to the V5 a car assembmed from parts not all by the same manufacturer!

No problems

Some updates


http://www.facebook.com/LotusSportster7/posts/881173482000162