Need some Spring advice... Options

[D1A3]

I have a stock '76 2.0L car and have been pretty successful in AutoX at the local PCA and SCCA level. For PCA, I run in the PA class.

I currently have red Koni's (age unknown) with 90 pound springs on the car. I also have front and rear factory sway bars. The shock/spring combo seem to work well enough for street and reasonably aggressive driving

My problem is that my rear end seems to come up and dance all over the place when I'm AutoX'ing and I'm trying to get it more planted for the upcoming season. I've had folks recommend I upgrade my rear springs to everything from 140 up to 180 lbs.

Any thoughts on what springs I should go with? I'm not looking to replace the shocks and springs or do any other suspension changes right now as I can drive the car very well in AutoX, but want to try and pickup some handling and hopefully a little time.

Below is a pic of my car from behind to give you an idea of what I'm trying to correct.

Thoughts?



I appreciate any and all comments! :-)

[okieflyr]

Have you had the opportunity to take any of the Evolution driving classes yet?
The series of these courses will give you a new insight on how to maximize everything the car will give you. This knowledge and developing skills will get you more of that time your looking for no matter the cars capability.

My basic driving driving advise is to keep everything smooth and fluid. A lot people don't understand how the weight transfer affects traction and ultimately the the direction the car is pointing for the next gate and then have to overcompensate for the rest of the course. This can be even more important
on lower horspower momentum cars.

You do sound confident and successful thus far and good for you it's alot of fun!
The changes made at one end of the car will affect the other end as well.
It can be a very slippery slope, so you'll want check what the spring and other changes will make in regards to the car classification.

[stewteral]

I have a stock '76 2.0L car and have been pretty successful in AutoX at the local PCA and SCCA level. For PCA, I run in the PA class.

I currently have red Koni's (age unknown) with 90 pound springs on the car. I also have front and rear factory sway bars. The shock/spring combo seem to work well enough for street and reasonably aggressive driving

My problem is that my rear end seems to come up and dance all over the place when I'm AutoX'ing and I'm trying to get it more planted for the upcoming season. I've had folks recommend I upgrade my rear springs to everything from 140 up to 180 lbs.

Any thoughts on what springs I should go with? I'm not looking to replace the shocks and springs or do any other suspension changes right now as I can drive the car very well in AutoX, but want to try and pickup some handling and hopefully a little time.

Below is a pic of my car from behind to give you an idea of what I'm trying to correct.

Thoughts?



I appreciate any and all comments! :-)

Hi D1A3,

I agree that you want to REDUCE ROLL in corners. Not only does it take TIME to load and unload the chassis, but roll makes the rear suspension do a LOT of Toe-change: for every 1" a rear wheel compresses (goes up) the suspension on that wheel toes-in .100". At the same time the other rear wheels toes-out a similar amount, creating understeer. A good rear toe setting starting point is "0"
toe and going to static toe-out to allow the rear to move a bit. An oversteery car is quick at lower speed auto-x's

I think starting at 140 lb spring AND stiffening the swaybars will improve the car. Keep in mind that with the mounting of the rear coil-over, the actual wheel rate is 117% X the spring rate.

If you can adjust the swaybars stiffer, great, but you may need to go a size large. Don't make a big jump as the spring rate of the swaybar increase at the 4th power of the diameter. Here's the formua: K = (1,178,000)(D4/LA2)
Swaybars are a great spring to reduce roll while keeping all the wheels on the ground.

I wish I could give SPECIFIC answers, but my car is a V8 track car and I'm running 400 lb rear spings.

Best,
Terry

[J P Stein]

Take heart, many drivers never reach the limitations of the stock (optional?) F & R sway bar set-up.

I'm not familiar with the class you're running (PA)...PCA is odd. If it is showroom stock, you're stuck.

The cure for lifting the inside rear is well known but requires some changes that may put you out of your class.

The problem is the rear AR bar. You could simply disconnect it but I think that would cause the front end to push.....not good for AX....tho you may want to try that. The cure for that is 140lb rear springs with no rear bar......a common point in the 914 AX modification process.

Whatever tires you are running have more grip that what was available 40 years ago.
Adding R spec tires (more grip) will exacerbate the lifting.

When the inside rear lifts all forward thrust ceases and upsets the car. A clutch type LSD will also cure this but it gives another handful of challenges while lightening your wallet. (IMG:style_emoticons/default/biggrin.gif)

[Joe Ricard]

Better shocks is about all you can do to improve Stock class cars.
Koni is a good start
Fox, JRZ, AST, are steps up in no particular order.

Penske and Moton are flat out magic shocks.

[ChrisFoley]

I agree with JP for the most part.
140lb rear springs and a 19mm adjustable front a/s bar with no rear bar.
Better suspension bushings would be helpful as well.

[grantsfo]

Your car is just exhibiting characteristics from soft stock setup. Going to bigger adjustable 19 mm to 21mm front swaybar and 140 lb rear springs will cure the car of excessive roll. Consider getting adjustable collars for the rear shocks as well as your car could be lowered a bit. This combo has been proven for decades on many 914's.

I wouldnt waste mone on expensive shock on a stockish 914. The car isnt really comptitive in SCCA realm in stock class. If your koni's are in good shape they are fine for your purposes.

Tires are huge opputunity. Hankook RS3 in 205/50/15 Or Toyo R1R in 195/55/15 (thats the cheater tire for SCCA guys). If your class lets you run DOT R then Hoosier A6 or Good Year RS in AC compound are your only real choices.

It you run DOT R tires dont forget to grab as much negative camber as you can achieve. Hoosiers and Good Years like as close to -3 as you can get.

This post has been edited by grantsfo: Mar 8 2012, 12:30 PM

[D1A3]

I agree with JP for the most part.
140lb rear springs and a 19mm adjustable front a/s bar with no rear bar.
Better suspension bushings would be helpful as well.

Racer Chris, didn't we race at the SCCA event in Huntsville a couple years ago after the Rocket City Ramble? I think you had flown in and were driving a "borrowed" car.

Anyways, what is impact will running the 140 pound springs with a factory rear roll bar? I see a few folks have said to pull that, but why is leaving it on a negative?

Sorry for such questions, but I'm really not that up on all of this and appreciate the groups more seasoned advice! :-)

Thanks,
Jason

[jhadler]

It's all how a sway bar works... A sway bar is basically a spring that couples the left and right suspension. The more the outboard side compresses, the more force will compress the inboard side. The net effect, because the "spring" is anchored to the chassis, is to use the suspension compression to keep the chassis flatter. The downside of this is that the more you couple the two sides, the more likely you are to lift the inside wheel.

In the front we see this all the time with the inside front wheel hanging just above the ground when the car is pulling hard out of a turn. This is the result of a stiff front sway bar. The outboard side compresses, and that force is coupled to the inboard suspension, resulting in wheel lift. It also has the effect of helping keep the chassis flatter in the turn. This helps minimize wheel lift in the rear.

In the rear, a sway bar will do the same thing. Only now, you're lifting up on a drive wheel. This is not what we want...

So... The general concept for a "slightly more than stock" configuration, is to increase spring rate in the rear, disconnect or remove the rear sway bar, and increase the rate of the sway bar in the front.

Hope this helps...

-Josh

I agree with JP for the most part.
140lb rear springs and a 19mm adjustable front a/s bar with no rear bar.
Better suspension bushings would be helpful as well.

Racer Chris, didn't we race at the SCCA event in Huntsville a couple years ago after the Rocket City Ramble? I think you had flown in and were driving a "borrowed" car.

Anyways, what is impact will running the 140 pound springs with a factory rear roll bar? I see a few folks have said to pull that, but why is leaving it on a negative?

Sorry for such questions, but I'm really not that up on all of this and appreciate the groups more seasoned advice! :-)

Thanks,
Jason

[D1A3]

SUPER! Thanks for the advice guys. :-)

[Borderline]

It took me a long time to figure out how flexible the 914 chassis is. All the suspension tuning I was trying to do, the car pretty much felt the same. Some of the guys around here were running their targa tops tightened down good and tight to get some chassis stiffness. I made my own C/F targa top and attached it rigidly and it made a huge improvement. I would recommend running with the targa top installed and stiffening both ends of the car to reduce body roll. If you feel the inside rear tire spinning at corner exit, you may want to try removing the rear bar and see if it helps. FWIW

[Randal]

It took me a long time to figure out how flexible the 914 chassis is. All the suspension tuning I was trying to do, the car pretty much felt the same. Some of the guys around here were running their targa tops tightened down good and tight to get some chassis stiffness. I made my own C/F targa top and attached it rigidly and it made a huge improvement. I would recommend running with the targa top installed and stiffening both ends of the car to reduce body roll. If you feel the inside rear tire spinning at corner exit, you may want to try removing the rear bar and see if it helps. FWIW

And listen to Bill as his 914 will break your neck on a corner. And he accomplished that without a cage which is pretty impressive. You gotta love the engineers!

No question body lean is something that 914's don't like. If your driving corners on the limit body lean will induce spinning IMHO, especially in high speed sharp transition corners.

[J P Stein]

Old pic with a 19mm front AR bar set full soft & & 140lb rear springs.
Worked gud.....shoulda quit there. My retirement would be more comfortable. (IMG:style_emoticons/default/biggrin.gif)

[Borderline]

Hey JP, what flairs are those? What tires were you running under there? I may eventually have to flair the rears and yours look good. How big did they let you go?

[J P Stein]

Hey JP, what flairs are those? What tires were you running under there? I may eventually have to flair the rears and yours look good. How big did they let you go?

The tires were Victorracers 205s & 225s X15.

The flares were free.......just a hammer & dolly to the original fenders....bout 10000 whacks apiece. That's hard on the hands but mine still worked back then. (IMG:style_emoticons/default/biggrin.gif)

I tried to stretch the rears more to cover 10 inch slicks but that
was a bridge too far......but I got close, maybe 3/4 inch short of width.

The front flares ( I originally moved the fender opening up bout 3/4 inch) did cover the 10 inch slicks with a 5.5 inch backspace wheel. The pic shows full compression of the front suspension......also did lock to lock. A few minor adjustments were needed.

[ChrisFoley]

Racer Chris, didn't we race at the SCCA event in Huntsville a couple years ago after the Rocket City Ramble? I think you had flown in and were driving a "borrowed" car.

Yup.
I was co-driving Scott Bradley's car.
I had to leave early and catch a plane in Nashville though.

As Josh said, keeping the rear sway bar will create wheelspin on corner exit - which will kill your times.

[Borderline]

Hey JP, what flairs are those? What tires were you running under there? I may eventually have to flair the rears and yours look good. How big did they let you go?

The tires were Victorracers 205s & 225s X15.

The flares were free.......just a hammer & dolly to the original fenders....bout 10000 whacks apiece. That's hard on the hands but mine still worked back then. (IMG:style_emoticons/default/biggrin.gif)

I tried to stretch the rears more to cover 10 inch slicks but that
was a bridge too far......but I got close, maybe 3/4 inch short of width.

The front flares ( I originally moved the fender opening up bout 3/4 inch) did cover the 10 inch slicks with a 5.5 inch backspace wheel. The pic shows full compression of the front suspension......also did lock to lock. A few minor adjustments were needed.

You did a nice job, JP. Pounding metal is one of the many things I don't do....well or otherwise.

[Woody]

JP that looks great.

[J P Stein]

]

You did a nice job, JP. Pounding metal is one of the many things I don't do....well or otherwise.

I had 0 experience with metal shaping when I started......I had just read that there was a sufficient thickness of the original metal to do it......uh....OK. It was the dead of winter so what better d than to spend some quality (?) time with the 914. (IMG:style_emoticons/default/biggrin.gif)

I did find that there are dollies and there are dollies.....I bought a good one and several bad ones. I already had a large selection of hammers. A 16 OZ ballpeen turned out to be the best. This smiley was added to the list during that period.(014 club days) (IMG:style_emoticons/default/smash.gif) Believe me when I tell ya that one has plenty of time to observe how metal works and go from there. Got an old progress pic somewhere.
Once ya start whacking the thing there's no turning back. Other 914 guys have done it over the years with equal or better results.

[MHKflyer52]

I have a stock '76 2.0L car and have been pretty successful in AutoX at the local PCA and SCCA level. For PCA, I run in the PA class.

I currently have red Koni's (age unknown) with 90 pound springs on the car. I also have front and rear factory sway bars. The shock/spring combo seem to work well enough for street and reasonably aggressive driving

My problem is that my rear end seems to come up and dance all over the place when I'm AutoX'ing and I'm trying to get it more planted for the upcoming season. I've had folks recommend I upgrade my rear springs to everything from 140 up to 180 lbs.

Any thoughts on what springs I should go with? I'm not looking to replace the shocks and springs or do any other suspension changes right now as I can drive the car very well in AutoX, but want to try and pickup some handling and hopefully a little time.

Below is a pic of my car from behind to give you an idea of what I'm trying to correct.

Thoughts?



I appreciate any and all comments! :-)

One thing to do is keep a record of what you change. By this I mean write it down and keep a log of the changes so you know what works and what dose not. Even little changes such as tire pressures. Once you change something and you find it dose not work well you will want to go back and set it to where you started before the change as that will be the point that you know the best but without a log of what you changed you will be just shooting in the wind per-say.

I do agree with J P Stine that 140Lb Rear Springs and a 19mm front sway bar with no rear sway bar will help a lot but their are also a number of other things to consider such as well worn shocks and bushings for one place to look before making changes.

Have fun.

Martin Keller
Ventura, CA.