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If You Look at Old Solid Axle Racers, You'll See Positive Camber

05/24/2016 3:24 PM

If one looks at pictures of very old solid axle race cars Why would they with a with a great hunk of iron at front need it's front handling degraded by having POSITIVE camber? These days, you'll see a bit of NEGATIVE camber on all wheels despite much more favorable weight distribution and wide, flat tires, This tends to compensate for body lean and tire deflection under cornering loading.

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#1

Re: If you look at OLD solid axle racers, you'll see positive camber

05/24/2016 3:35 PM
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#2

Re: If you look at OLD solid axle racers, you'll see positive camber

05/24/2016 5:04 PM

sounds like a gas

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#3
In reply to #2

Re: If you look at OLD solid axle racers, you'll see positive camber

05/24/2016 5:25 PM
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#4

Re: If you look at OLD solid axle racers, you'll see positive camber

05/24/2016 5:26 PM

Some factors I've seen is that it lessens steering effort and it puts the tire contact patch underneath the wheel bearing.

http://www.jalopyjournal.com/forum/threads/why-postive-camber-on-beam-axles.758599/

Why Postive Camber on Beam Axles? | The H.A.M.B.

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#5

Re: If You Look at Old Solid Axle Racers, You'll See Positive Camber

05/24/2016 11:58 PM

Several considerations come to mind.

1. On road cars, this was done to improve tire wear on narrow roads with a great center hump. Could not be done at the rear with solid, driven axle.

2. With narrow wheels and tires the effects of cornering forces did not cause such uneven wear as is the case with modern wide ones. Toe-in was critical.

3. The self-centering depends partly on the castor angle and king pin inclination. On the early cars, at significant amounts of lock, the outside wheel will come upright and the inner wheel will lean even more outwards.

4. In extreme cornering, a little positive camber at the front helps reduce oversteer.

Must be a lot more to read on the evolution of suspension geometry!

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#6
In reply to #5

Re: If You Look at Old Solid Axle Racers, You'll See Positive Camber

05/30/2016 4:22 PM

UH-- we may differ! they degraded the handling of cars at the front because 99.9995% don't know how to handle oversteer so production cars at least in the past PLOWED when agressively attacking a corner at speed. One typically cranks NEGATIVE camber into the front so when the car leans out, the wheels STILL keep most of the tread spread across the pave for maximum adhesion despite often an unfavorable F/R weight distribution with the lump on the front wheels.

These OLDE racers had this in spades with GIANT cast iron lumps up front but they STILL decreased front adhesion. This probably was because when they were coming out of a corner and wanted to be at WOT the rear tyres weren't capable of handling BOTH the HP and cornering force. Maybe the typically larger rear tyres have to some extent resolved this with the later cars like INdy that STILL used solid axles.

IDEAS?

BTW we DO add negative camber to the rear by bending the solid axles at the centre making the sloppy splines work at a bit of angle

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#7

Re: If You Look at Old Solid Axle Racers, You'll See Positive Camber

06/09/2016 8:02 AM

I put it down to ignorance at the time.

I even had a Hillman Imp with it, but I simply added some aftermarket bits of metal to lower the height of the front wishbones and straps to completely prevent positive camber and that car "flew" round corners.....

But, the warnings that positive camber give to the driver when adhesion is dropping in a corner, were basically gone or far reduced!

For me, very slight negative camber was best on a flat road, , it just needed a slightly better driver!! But the bonuses were huge......not forgetting, the tyre wear was more even over the width of the tread, no need to reverse the tyres in any way shape or form....

I knew a guy with the same type of car and he had 50 kilos of extra weight up front, in the dry better, but in the wet it just went straight on!!! He copied me as it was cheap to do and he liked the results immensely....

This picture may help to understand better:-

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#8

Re: If You Look at Old Solid Axle Racers, You'll See Positive Camber

06/10/2016 4:33 PM

I'm not sure, but one thing that came to mind is that they weren't very good handling cars. It may have needed to be this way, because of the geometry of the suspension and if the cars needed heavy braking to get around a corner, the positive camber may have become neutral as the front end dove.

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#9
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Re: If You Look at Old Solid Axle Racers, You'll See Positive Camber

06/10/2016 9:43 PM

Drivers weren't stupid then--tho that's debatable about all of us racers, they had no seatbelts, rollover bars, a very high CG and usually horrible roads and OH yes, no flame proof suits, helmets neck braces etcetcetc! Nowdays, you're in about a $K in safety prep! --and that's for vintage racing your 70 Hp MG!

They MUST have tried about everything they could and ended up with what they did: positive Camber! Tyres weren't starting to offer more tread until the 70's, My Lotus had Dunlop Green spots, about 4" tread so they were about like motorcycle tyres now~~

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