Suspension questions and suggestions?

[Eric F]

Good evening fine roadster folks!

Well, after visiting the infamous "Tail of the Dragon" in Tennessee/North Carolina last weekend, I have come to the conclusion that my '70 2000 is in dire need of some new springs and probably a comp sway bar to make it just a bit more fun on the curves...

Right now, I see my front stock bump stops (uncut) are within 1/2 inch of the frame and have been hitting from time to time. It appears that I have stock springs, but they look to be cut to lower the car...

Rear springs.. when the car is flat on the ground, the springs would appear to be sagging quite badly, like about 2 inches upward instead of perfectly flat.

I am looking to keep this car very street legal and drivable, but want to make it a tad more aggressive. Any suggestions on what to do?

Eric

[S Allen]

My suggestion-go with a set of Mike Youngs's springs in the front with some new shocks. Cut the bump stops to match. Add a competition sway bar and eurathane bushings from one of the other vendors. I would steer clear of the competition rear springs as they are flat and will lower the rear end of the car. I would say get your rear springs re-arched. Several have had it done and seem to be quite satisfied. Adding set of new rear shocks cannot hurt either. I think adding a rear sway bar is a waste of time on a street car but then that is just me. And to finish off put a set of good sticky shoes (tires) on to make it hug the road.


Steve

[Conner]

As an alternative to cutting/shaving your stock front bumpstops you could pick up a pair of these from Energy Suspension:



They are eurethane, not rubber, so if they do bump they won't be as forgiving, but they should last a long time. They are around $8.50 for the pair--I bought mine from Summit. Part # is 9-9103. You may have to drill or tap the mounting hole just a hair to get the shafts of these to go on, here's how they look mounted:

[hport]

Andy,

What is the height compared to stock? Nice looking setup!

Eric,

If you are rolling on to the stops during cornering, you cannot fully use the sway bar to off set body roll, therefore the front suspension cannot compansate. With stock height front springs the center of gravity is higher and again non contusive to anti-roll. Urethane is a good thing , just not at stock height, like Andy said it lets you know if you're on them in a big way. The idea is to allow full suspension compansation thru the sway bar with just a touch of bump stop at the end on a hard turn.
The simple version of a great set up is, can you pull the inside wheel off the ground when cornering? You will need stiff lower rear springs with panhard bar, and same for the front springs, Koni or KYB shocks, valved for quicker reponse and a larger front sway bar in urethane or delrin mounts to handle the load. Most of all, increase in ball size is going to be required if you decide to go down this path.
This all depends on how much do you want to spend to go a tad faster in the turns.


2 cents,
John

[Eric F]

I could feel the car hitting every now and again, but honestly was having too much fun on the road. We have some pictures of the trip that maybe you guys could check out and let me know what you think?

http://www5.photoreflect.com/scripts/pr ... 99&b=10216


My rear springs are completely shot.. I thought about re-arcing them, but it's apparently as expensive as getting the comp springs. I knew that the comps were practically flat, so putting them on my car now would actually RAISE my car about 2 inches in the rear. Sad, eh?

I'm definately interested in the Mike Young springs now... read the info on his site and seems to be a well manufactured spring!

Andy, that is one slick setup and just the right price! I will definately be buying some of those soon! thanks for the tip!

Eric

[Conner]

Those ES bumpstops are about 1 1/2" in height, which is around 1" shorter than the originals, IIRC. You may need a 7/16"-20 tap (or a 1/2" drill bit) to widen the mounting hole to accept them, but it is pretty easy to do.

For rear springs I looked high and low, even inquired to some custom spring-makers about fabbing them to spec. I was looking for some early car springs, which are the ones Bob Sharpe recommends using because they are a little lower and stiffer than the later car leaf springs, but not as severe as the comp springs, which I was told are a pretty harsh ride. Oregon Springs (www.spring-man.com offered to do them for $300/pair for six pairs, but I couldn't find five more buyers on this forum at the time). Ultimately I ended up getting a new pair from Rallye--check his website for prices and availability. It is worth trying all of the vendors to see who has them.

[nomadtrash]

The rear springs on the roadster are angled down and inwards towards the front. This causes the rear axle to go up and forwards when hitting a bump or going around a corner. This motion causes a rear steer effect. An old racer trick is to flip the rear shackles upside down which raises the rear of the car about 3". You then add some lowering blocks between the shring and the axle to bring the ride height back to the proper level. When flipping the shackles you make the front and rear of the spring at about the same level. They still angle in at the front but the rear steer effect is minimized.

The comp rear springs are basically flat and arch upwards when loaded. It may be that you already have comp rear springs installed. The front comp springs have thicker wire diameter than the originals. They may have fewer coils also.

I would recommend getting the comp or addco front swaybar and comp or Mike Young front springs. The Koni shocks are really good and can be adjusted for more or less damping. The KYB GR2 are good compromise for good street manners. The KYB gas adjust are pretty harsh.

The biggest issue with handling is the bump stop. Handling is all about weight transfer. You want to keep weight transfer to a minimum. The more weight that is put on a tire the less relative grip it has. When you corner the weight transfers due to centrifugal acceleration and due to the change in the weight distribution as the center of gravity changes when the body rolls. The centrifugal weight transfer can't be lessened unless you go around the corner slower. The weight transfer dut to body roll can be lessened by using stiffer springs and bigger anti-roll bar.

When you hit the bump stop the weight transfer goes to 100% on that wheel. The tire immediately loses all traction. The end of the car that has hit the bump stop will skitter off the outside of the corner and there isn't much you can do about it. By stiffening the springs, adding a larger front bar, and cutting the bump stops you lessen the chance of transferring too much weight.

The tires are an important thing too. Having the right tires can make huge difference in the feel and abilities of the car. I suggest Falken Azenis 215 or Falken Azenis 615 for the roadster. The size 195/60/14 are usually around $50 and they are very sticky. They last a decent amount of time.

Later,

[dbrick]

I was going to also suggest flipping the shackles, it's free, and unless the rear spring rate is way low, should help. I thought the part John mentioned about hitting the stops in cornering was a bad thing, but I don't autocross.

Andy, correct me if I am wrong on a theory thing. In an otherwised balanced handling car, adding a rear sway bar or increasing rear bar size will lessen body roll, but INCREASE understeer?
Read something the other day, head started spinning. been too long since I played suspension theory.

[nomadtrash]

The stiffer end of the car tends to slide the most. The problem with the roadster is that the comp front swaybar isn't stiff enough so the rear still slides more. Adding a rear swaybar only makes the problem worse. Many race roadsters have a very large front bar and a small or no rear bar.

I fixed my problem by cutting the car weight down to 1725 pounds which makes the spring rate and bar larger relative to the unsprung weight. I still don't run a rear bar. With the huge slicks that I'm installing in the rear and the three link with coil overs I may end up with too much push. I have a rear bar that I might actually get to use.

[hport]

Judging by the pictures the roadster has less roll then the Mini.
You were going as fast or faster.......right?

Another point on roadster suspension, you can make small changes and see how you like it. No need to go all out, if you are happy with the upgrades you are doing. The suggestions are all on the same track, so you have a good idea of how to proceed.

I keep hearing good things about the Falken road race tires, and cheap to boot........ Tire Rack??

[Eric F]

Oh yeah, we were going about as fast.... That Mini handled the curves really nicely as well. The roadster was just tons more fun though with the squealing tires, top down and loud engine!

Thanks for the tips and suggestions! I have my work cut out for me now!

Eric

[dbrick]

Th flip was something I saw in "How to Make Your Car Handle", great book. explains the whole bumpsteer/spring angle thing. How are the tires you have now?

On the 70, it's much easier to flip if you remove the torque link first, reinstall after the flip. Learned the hard way. We did it on a lift with a BIG bar, I don't think we unbolted anything. Way back when I had my first roadster, 20 some years ago, pre internet, I thought I was on the cutting edge doing the spring flip. (Sold it in 87, never saw another one until I bought mine in 2004)