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EM Front coil springs
Posted by: loots ()
Date: February 28, 2018 06:44AM

After hours of searching and reading… My question, I have a 62, I am in the middle of installing 64 front lower A-arms allowing me to use the 64 stabilizer. Without thinking a couple months ago, I ordered the 60-63 coil springs for the front. Apparently there is a difference. Are the 60-63 front springs stiffer than the 64 because of the stabilizer?...


My plan has been to go to all 64 front and rear suspension… After reading, searching and reading more I am now thinking the 64 rear transverse suspension isn’t all that necessary. Maybe stick with the 64 front and the 62 rear that is in the car already. Since the 60-63 rear coils are stiffer than the 64s, I may have helped my cause dramatically with the front-end swap alone. My goal has been to make the car a little more stiff for “spirited driving”. Thoughts and comments, please. Thanks a bunch!





Arlington, Washington
1962 Monza 110/PG

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Re: EM Front coil springs
Posted by: blackspyder ()
Date: February 28, 2018 07:12AM

I have a 63 Spyder, I cannot tell you if there is a difference in the front springs between a 63 and 64, but I converted the rear to the transverse leaf spring and put the late model front sway bar on, and used stock spyder springs.
The car is much more stable and handles way better this way. If you do a search on here it has been talked about many times. The larger 65-69 sway bar on the front makes the car handle much better, I changed the middle sway bar mounts to late model.

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Re: EM Front coil springs
Posted by: loots ()
Date: February 28, 2018 07:59AM

Oh! So the late model bar is larger... I knew this but I didn't think it was that much bigger that it would make that much of a difference. Thank you for the information.

Arlington, Washington
1962 Monza 110/PG

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Re: EM Front coil springs
Posted by: 66vairman ()
Date: February 28, 2018 08:30AM

blackspyder Wrote:
-------------------------------------------------------
> I have a 63 Spyder, I cannot tell you if there is
> a difference in the front springs between a 63 and
> 64, but I converted the rear to the transverse
> leaf spring and put the late model front sway bar
> on, and used stock spyder springs.
> The car is much more stable and handles way
> better this way. If you do a search on here it
> has been talked about many times. The larger
> 65-69 sway bar on the front makes the car handle
> much better, I changed the middle sway bar mounts
> to late model.

A few of us in the local club went through this with an EM member. This is what was we came up with and if incorrect others are free to correct.

The 64 sway bar is suppose to be slightly larger than 62-63, BUT some of the anchoring hardware is reported to break (LM cars had more robust attachments and a larger front sway bar).

Many years ago a gentleman posted here that he used the LM front suspension and sway bar WITH the EM spindles and brake drums to keep the four bolt wheels and the EM front track is slightly narrower (probably the narrower brake drums). This was on a wagon and he reported a considerable improvement in handling - in his opinion. I may still have the article, PM if you want me to look for it.

For extreme maneuvers the 64 "leaf spring" rear suspension is superior. It not only prevents rear wheel tuck under, it also lowers the rear roll center for better handling. A bonus is the ride is better (the 64 rear springs are unique). Don't confuse the 64 rear design with aftermarket limiters, the GM 64 design was more sophisticated and works better.

Anyway that was the general consensus in the group.



Edited 1 time(s). Last edit at 02/28/2018 08:32AM by 66vairman.

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Re: EM Front coil springs
Posted by: Frank DuVal ()
Date: February 28, 2018 09:16AM

Quote
loots
Since the 60-63 rear coils are stiffer than the 64s

This is because the rear leaf also picks the car up. If you put 60-63 rear springs on a car WITH the 64 leaf, it will be on tippy-toes! Extreme positive camber.eye popping smiley

Frank DuVal

Fredericksburg, VA

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Re: EM Front coil springs
Posted by: 66vairman ()
Date: February 28, 2018 10:53AM

just my 3 cents - but I learned that "stiffer" springs don't necessarily mean better handling.

With good shocks,tires, and the LM front sway bar set up and the EM 64 rear suspension you'll have a car that handles and rides good.

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Re: EM Front coil springs
Posted by: loots ()
Date: February 28, 2018 02:00PM

I would agree with that statement. Anything at this point will be a huge improvement. Think I will stick with my original plan. 64 front and rear. Since I already have the 64 stuff for the front I'll finish that up. Next fall I'll tackle the rear. Thanks for all the input.

Arlington, Washington
1962 Monza 110/PG

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Re: EM Front coil springs
Posted by: JerryM ()
Date: March 01, 2018 06:37AM

Any time the topic of EM handling and chassis design comes up there's some misunderstoop concepts regarding the '64's. The transverse leaf's purpose is to "de-stabilize" (de-couple) the roll of the rear wheel pair. Nothing to do with camber or any effect on the roll center of the car: "camber compensator" is a misnomer. In essence it is the opposite of the front stabilizer. It contributes nothing to roll rate, which is very desirable for this purpose, - no roll rear rate means no rear roll! In the case of the Corvair with it's weight distribution and C.G., it may be possible to dispense with the rear coil springs entirely: have zero rear roll rate! In conjunction with a front "stabilizing" link(sway bar-required) will yield the best results. As the de-stabilizing link will add ride rate, the rate of the front coils will need to be selected as necessary to provide a flat ride if that's important to you.



Edited 1 time(s). Last edit at 03/01/2018 06:39AM by JerryM.

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Re: EM Front coil springs
Posted by: 66vairman ()
Date: March 01, 2018 08:12AM

Jerry that's interesting, but since you want to bring in roll rate lets back up and take a look.

Many things affect roll rate, but basically the higher the car (or truck) center of gravity the more it wants to roll to the side in a turn. The roll center is the point the suspension rolls about. Obviously you want both lower to the ground vs. higher.

Pictures of an EM in a tight turn show the rear wheels tucked under the rear forcing the back end up in the air (roll center goes high) this is what the 64 rear suspension counteracts, or effectively reduces the roll center. Many Corvair books talk about this and have illustrations.

The roll rate can be reduced with either stiffer coil springs or a sway bar, BUT too much stiffness results in poor wheel contact on anything but smooth and flat pavement. Bumps and undulations can really "upset" a car with stiff suspension.

On a rear engine car it's usually preferable to have higher roll resistance up front vs. the rear. Porche did this rather successfully to cause the inside front wheel to lift in a tight turn so the front end would tend to drift while both rear wheels stayed firmly planted to maximize rear traction and to counteract oversteer. You'll see old Porche pictures with the inside front wheel up off the ground.

If your point was a rear sway bar or stiffer rear springs would not be a good thing on a Corvair, yes that's correct. It's also been noted in books the 64 had a better ride due to the "softer" rear spring rate. It would probably more accutate to say the 64 rear spring rate was variable.

Of course there's a lot more to it, tires, track type, etc. For driving on public streets (with all their variations) a good stock 64 suspension with radial tires and proper front rear tire pressure difference is a good set-up.

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Re: EM Front coil springs
Posted by: JerryM ()
Date: March 01, 2018 09:18AM

Jerry that's interesting, but since you want to bring in roll rate lets back up and take a look.

Many things affect roll rate, but basically the higher the car (or truck) center of gravity the more it wants to roll to the side in a turn. The roll center is the point the suspension rolls about. Obviously you want both lower to the ground vs. higher.


True, roll moment is determined by RC/CG. EM's don't have an issue here as they have a very small moment arm.

Pictures of an EM in a tight turn show the rear wheels tucked under the rear forcing the back end up in the air (roll center goes high) this is what the 64 rear suspension counteracts, or effectively reduces the roll center. Many Corvair books talk about this and have illustrations.

Many "Corvair Books" are wrong. Roll center is not dynamic. "Jacking" is due to high spring rate. The 64's low spring rate and transverse springs de-stabilization (roll de-couple) opposes jacking.

The roll rate can be reduced with either stiffer coil springs or a sway bar, BUT too much stiffness results in poor wheel contact on anything but smooth and flat pavement. Bumps and undulations can really "upset" a car with stiff suspension.

Spring stiffness adds roll rate.

On a rear engine car it's usually preferable to have higher roll resistance up front vs. the rear. Porche did this rather successfully to cause the inside front wheel to lift in a tight turn so the front end would tend to drift while both rear wheels stayed firmly planted to maximize rear traction and to counteract oversteer. You'll see old Porche pictures with the inside front wheel up off the ground.

Early VW/Porsche is closer to the true definition of swing axle with a high CG and long roll moment arm. Later 911's are similar with the roll center on the ground and CG quite high(around 22 inches). The Corvair is -not a true swing axle – in fact a semi trailing arm design, EM's and LM's alike. The CG on an EM is near the transaxle centerline and RC slightly below. LM's similar.
The Porsche's lifting inside front wheel…a lot of roll torque in the rear and very stiff up front




If your point was a rear sway bar or stiffer rear springs would not be a good thing on a Corvair, yes that's correct. It's also been noted in books the 64 had a better ride due to the "softer" rear spring rate. It would probably more accutate to say the 64 rear spring rate was variable.


Of course there's a lot more to it, tires, track type, etc. For driving on public streets (with all their variations) a good stock 64 suspension with radial tires and proper front rear tire pressure difference is a good set-up.

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