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Old 03-05-2011, 07:22 PM
 
Location: Central Texas
13,720 posts, read 24,608,598 times
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You can IMPROVE it, but you cannot make a 60s leaf spring car handle twisty roads like a car with IRS.

The classic leaf spring suspension uses the leaf springs to both support the vehicle and control the lateral position of the axle. Leaf springs are at least adequate in the vertical plane, but are generally terrible laterally. They flex, they wobble, they twist - which all contributes to poor control of the wheels. The solid axle guarantees that on rough pavement both tires will react to surface defects, even if only one tire actually sees a bump in the road. Sometimes a "panhard" rod is added to control lateral movement.

Modern live axle cars (like the Mustang) use various combination of links to control both the vertical and lateral movement of the axle.

See the link below for a very good overview of the Mustang's rear suspension:

Late Model Mustang Suspension Basics
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Old 03-06-2011, 08:42 AM
PDD
 
Location: The Sand Hills of NC
8,776 posts, read 14,134,753 times
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Quote:
Originally Posted by hoffdano View Post
You can IMPROVE it, but you cannot make a 60s leaf spring car handle twisty roads like a car with IRS.

The classic leaf spring suspension uses the leaf springs to both support the vehicle and control the lateral position of the axle. Leaf springs are at least adequate in the vertical plane, but are generally terrible laterally. They flex, they wobble, they twist - which all contributes to poor control of the wheels. The solid axle guarantees that on rough pavement both tires will react to surface defects, even if only one tire actually sees a bump in the road. Sometimes a "panhard" rod is added to control lateral movement.

Modern live axle cars (like the Mustang) use various combination of links to control both the vertical and lateral movement of the axle.

See the link below for a very good overview of the Mustang's rear suspension:

Late Model Mustang Suspension Basics
You are correct, you and I can't make leaf spring cars handle better but there are racers/mechanics that can and do outperform IRS cars on the racetrack.
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Old 03-06-2011, 09:02 AM
 
Location: norfolk
129 posts, read 298,826 times
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it dosnt matter what type of spring it is, whether coilover or leaf, a spring is a spring and perform the same function. Modern cars run stiffer springs, so this is a must, however anti roll bars can help.

Suspension geometry that affects weight transfer characteristics is what makes a difference in handling.

I would recommend finding a community of whatever specific car your working with and see the type of stuff they are doing.
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Old 03-06-2011, 09:53 AM
 
48,519 posts, read 80,998,062 times
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But its the design need to use leaf springs. That is why for best performance no car that is pueely designed for handling has them.
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Old 03-06-2011, 10:04 AM
 
Location: Pikesville, MD
5,229 posts, read 11,481,696 times
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On the original BOSS 302 mustangs, and on my own '70 mustang autocross racer, there were simple ways of dealing with it. One was staggered shocks, which help control axle wrap. another was clamping the front half of the leaf spring, effectively turning it into a trailing arm, third was stiffer shocks and larger swaybars, and las was a full floating axle housing that allowd the axle to move back and forth slightly on teh spring so it didn't bind up.

Unless a corner is severely bumpy, it's really all thats necessary to get them to handle well. it's not luxury car smooth, which is what IRS can get you (though you find that if you use larger swaybars and stiffer springs/shocks on an IRS car, you lose all the ride and it can become jumpy on bumpy corners, too)





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Old 03-06-2011, 11:26 AM
 
8,402 posts, read 19,527,792 times
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Quote:
Originally Posted by Merc63 View Post
On the original BOSS 302 mustangs, and on my own '70 mustang autocross racer, there were simple ways of dealing with it. One was staggered shocks, which help control axle wrap. another was clamping the front half of the leaf spring, effectively turning it into a trailing arm, third was stiffer shocks and larger swaybars, and las was a full floating axle housing that allowd the axle to move back and forth slightly on teh spring so it didn't bind up.

Unless a corner is severely bumpy, it's really all thats necessary to get them to handle well. it's not luxury car smooth, which is what IRS can get you (though you find that if you use larger swaybars and stiffer springs/shocks on an IRS car, you lose all the ride and it can become jumpy on bumpy corners, too)




What's different about the #68 Mustang in the last pic? It looks...different than the other Mustangs in your pics. Something about the rear quarter panels maybe.

I agree with the comments you made about swaybars on an IRS car. If I adjust the sways on my GTO to their stiffest setting, the rear wants to hop, even more than usual.
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Old 03-06-2011, 11:38 AM
 
Location: Spencer, Ohio
365 posts, read 1,147,597 times
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I'd head over to the forums at Pro-touring.com - Pro-Touring.com.
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Old 03-06-2011, 03:12 PM
 
30,879 posts, read 24,200,485 times
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Quote:
Originally Posted by hoffdano View Post
You can IMPROVE it, but you cannot make a 60s leaf spring car handle twisty roads like a car with IRS.
rubbish. first gen B production GT350 mustangs ran away and hid from A production corvettes and jaguars, as well as A production cobras, all of which used IRS.

Quote:
The classic leaf spring suspension uses the leaf springs to both support the vehicle and control the lateral position of the axle. Leaf springs are at least adequate in the vertical plane, but are generally terrible laterally. They flex, they wobble, they twist - which all contributes to poor control of the wheels. The solid axle guarantees that on rough pavement both tires will react to surface defects, even if only one tire actually sees a bump in the road. Sometimes a "panhard" rod is added to control lateral movement.
this is true only if you are using stock leaf springs, which are in fact rubbish from the factory. a good aftermarket steel spring, or better fiberglass leaf springs, work much better. with a proper set up you dont need a panhard bar or watts link with a leaf spring car.
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Old 03-06-2011, 05:06 PM
 
Location: Guangzhou, China
9,620 posts, read 12,783,261 times
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Quote:
Originally Posted by rbohm View Post
rubbish. first gen B production GT350 mustangs ran away and hid from A production corvettes and jaguars, as well as A production cobras, all of which used IRS.
Back in the 60's when IRS was a fairly new technology, maybe. It would take a lot of work to make a vintage car with leaf springs outhandle a modern sports car with IRS.

All that said, I used to own one of these:

and it was such a blast in the twisties! I used to take that thing up to the canyons; it sure wasn't cut out for uphill racing ('til I swapped out the old iron lump for a modern Toyota DOHC engine, at least), but on the downhills, the thing was so small and light, you barely needed to brake for most of the turns. After I'd swapped in the new engine and doubled its horsepower, I was more than happy to take on pretty much any modern sports car on a technical course, and I used completely stock rear suspension.
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Old 03-07-2011, 08:38 AM
 
Location: Pikesville, MD
5,229 posts, read 11,481,696 times
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Quote:
Originally Posted by vmaxnc View Post
What's different about the #68 Mustang in the last pic? It looks...different than the other Mustangs in your pics. Something about the rear quarter panels maybe.
The last pic is of a privateer '70 Mustang road racer. The first two are factory '69-70 Mustang road racers... The factory race cars had rolled rear fender flares, to make them bigger for the 12" wide tires. That last one has the stock rear fender flares.
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