Softer springs or not, that is the question

[AdamIsAdam]

Thanks for the reply. I have a local shop who specializes is race cars (including fabrication), all German cars and is actually building a FFR at the moment, ironically enough. He has the scales and alignment equipment to corner balance the car, which I plan on doing. And yes, I know all about cold summer tires in a big way! I have Nitto NT01's on the Cobra and a 2018 GT350 with Pilot Super Sports that I run all year (but only drive it on sunny days) so I know all too well how extreme summer tires dislike cold temps!

What is a good corner balance weight setting?

[Jeff Kleiner]

What is a good corner balance weight setting?

You want to have both diagonal pairs equal. It isn't a setting per se.

Jeff

[AdamIsAdam]

Sorry, "setting" is not the right term. I mean in general, what's the ideal (or a good starting point) percentage to look for with a small block FFR? 48% front/ 52% rear?

Diagonal pairs equal? Interesting. What's the logic behind that? I would think you want the fronts equal, and the rears equal, and then you want what the car likes best front/rear (ie, if 48/52% F/R was the ideal). This assumes balanced driving and not something like nascar that is only left turns. Again, I'm looking for the most predictability here on the street.

[Jeff Kleiner]

Adam,
You're not grasping the concept and are confusing static weight distribution with corner weighting/balancing and cross weighting. You can't "move" weight with spring adjustments. If the front end of the car has 1,000 pounds on it and the rear has 1,200 pounds that is the static weight distribution and won't change with spring preload adjustment. HOWEVER what can change with spring adjustment is that you could end up with 400# on the LF, 600# on the RF, 700# on the LR and 500# on the RR. The front would still be a total of 1,000 pounds and the rear 1,200 so the weight distribution remains the same but the car is what I call "cross jacked" (some refer to it as "wedged" particularly in the circle track world). If the diagonals are not equal (or equalized as much as possible which is sometimes dictated by driver or component positions) the car will not perform the same cornering left as it does cornering right. A diagonal mismatch will also lead to poor braking with the lightweight wheel(s) locking up prematurely. I mentioned the circle track guys because they will intentionally "wedge" a car for left hand turns but in our case we want our cars to perform the same in both directions and not oversteer one way and understeer going the other!

That's probably clear as mud but the googles are your friend! There is a ton of info out there; check it out

Jeff

[Railroad]

Jeff,
I have the Wilwood 6 pistons on front and 4 pistons on the rear. I have manual adjuster on the master cylinders.
I was just feeling out the brakes to make sure the rears do not lock and cause a panic stop issue.
My right rear and left front slide on a hard stop.
It sounds like the car balance is off. I set the ride height by ground height, 4.5 inches all around.
I am sure it has settled some and needs re setting.
I doubt I will ever competitively track the car, but would like to have it at its optimum balance.
Your last post is telling me I need to balance the car before adjusting the brakes??
I can probably get on a set of scales of a local racer.
Sorry to interject brakes with handling, but they surely overlap.
Just wanted to glean as much info and apply before calling it done.
thanks for listening, to OP and others.

[AdamIsAdam]

Jeff,
I'm actually understanding what you're saying. But I will disagree that you actually can shift weight front to rear the same as you are shifting left to right in your example. 1000 lbs up front but 400# LF and 600# RF is doing the same thing as shifting it front to rear if you adjust the springs and ride height. I assume you would need much great adjustment settings to make changes since the center between front/rear is further from the wheels than is the center from left to right wheels. I'm not silly enough to think all cars can be made to be 50/50, because as you said, if a 911 has hundreds of lbs over (and behind) the rear axle, no amount of adjust is going to get that car to 50/50. But I think it could have an effect to some extent. Which is why I was asking if there's an attainable goal to shoot for.

If I understand your thought, it's to just make sure left/right are about balanced with each other, which would also make the opposing diagonals equal. That sounds easy enough to do.

I'll do more reading on Cobra suspension tuning. Coming to these forums is part of my homework, and I'll try more searching than posting. I'm just trying to understand the nuances of the Cobra specifically.

But I do appreciate your and others sharing your vast knowledge and experience. Honestly.

Weather was too crappy to take the Cobra out for a longer ride today. I selected the car with a roof instead

[rich grsc]

Jeff, sometimes it's just hopeless

[AdamIsAdam]

Hey, come on now. Play nice.

[Jeff Kleiner]

Jeff,
I have the Wilwood 6 pistons on front and 4 pistons on the rear. I have manual adjuster on the master cylinders.
I was just feeling out the brakes to make sure the rears do not lock and cause a panic stop issue.
My right rear and left front slide on a hard stop.
It sounds like the car balance is off. I set the ride height by ground height, 4.5 inches all around.
I am sure it has settled some and needs re setting.
I doubt I will ever competitively track the car, but would like to have it at its optimum balance.
You last post is telling me I need to balance the car before adjusting the brakes??
I can probably get on a set of scales of a local racer.
Sorry to interject brakes with handling, but they surely overlap.
Just wanted to glean as much info and apply before calling it done.
thanks for listening, to OP and others.

You're locking opposite diagonals which is a classic indicator that your cross weights are off with the RR and LF being light. I'd bet that your LR and RF adjusters are cranked more than the RR and LF. If this is the case change them (either up with one, down with the other or some of both) so that both fronts have the same number of threads showing. Now do the same with the rear. Note that the front and rear will not show the same number of threads. We want both fronts to match and both rears to match but the fronts won't match the rears. You may wind up with a bit of ride height variance, probably <1/4" but I bet it will solve the uneven braking. I've set the cars I've built up using this method and when scaled they were so close to dead on that they either needed no change or less than 1/4 turn.

Jeff

[AdamIsAdam]

That's probably clear as mud but the googles are your friend! There is a ton of info out there; check it out

Jeff

You were right. This article explains it well:
https://www.elephantracing.com/tech-...pring%20height.

and this

https://youtu.be/0uCUk30lP0s

[NAZ]

Adam, some candid tough love for you to consider.


These light weight, short wheelbase vehicles are not as forgiving as your standard passenger car. And they have little in the way of modern safety features and absolutely no nanny devices to prevent you from driving beyond your limit and ending up in a ditch or wrapped around a pole. It’s easy for an inexperienced driver to get in over his head – and that can have serious consequences. These cars are not for everyone and need to be treated with respect – they can kill you in a heartbeat.


To drive a performance vehicle near its limit requires knowledge, skill, and experience. To set-up a chassis on a performance car to make it handle optimally requires knowledge, skill, and experience. Adam, you seem to be short on KSE and are having trouble following the good advice of more knowledgeable folks. And you seem quick to dismiss their recommendations or even debate the advice given.

The best advice anyone here can give you is to take your poor handling car to that race shop you mentioned, open your wallet, and have the shop set-up your car to ride smoother with a neutral balance.
And while the shop has your car, go take a performance driving class so you’ll be better prepared to drive that car safely. These cars have gotten owners killed because they got in over their head. A high power to weight, short wheelbase car with loose handling is not something to take for granted.

[GoDadGo]

Adam,

These cars are a handful and learning to drive and adjust them takes time especially if you didn't build the car.
Ride height, corner weights, tire air pressure all need to be understood before spring rates get changed.

Please Do Your Best To Take It Slow So You Don't End Up Like This:
https://www.copart.com/lot/33551180/...la-baton-rouge

Just know that the fellows on the forum are like family and they are always here to help especially those who want to be helped.
For me, my friend Phil will soon be riding shotgun in Redbone after I learn the basics of my car and its abilities along with my own.

Steve

Phil's Gone A Bit Faster Than I Have!
https://youtu.be/hsvEx4vDVdg
https://youtu.be/zm2RdZ-FJmA
https://youtu.be/YTPvLRlmp7E
https://youtu.be/uFm3CM8_Zf8
https://youtu.be/JhR21Q24xHU

[AdamIsAdam]

I'm being very misunderstood and totally mischaracterized.

The Cobra is new to me, as is this forum, so I always try to come off as humble rather than conceded, especially since I am asking for knowledge and advice from those who know more than I do, which I appreciate. In fact, the selection of those springs was the advice of both FFR cobra builders and my local race car builder. And yes, he'll be aligning and corner balancing the car as originally planned. Please don't mistake humility for a lack of KSE.

[CraigS]

What I have found is that our FFRs are hard to get the corner balance as perfect as we would like. This is mainly due to the 150-250# driver sitting in the left rear of the car. The empty car is rear heavy by 2-3% but w/ the driver you end up w/ a car that is rear heavy and left heavy. If you try to get the front tires equal (which would be best for braking) you end up w/ the left side more rear heavy than the right side. My goal is to have about the same front to rear difference on both sides. I will fudge that a little to get the fronts a bit more equal.

[Railroad]

You're locking opposite diagonals which is a classic indicator that your cross weights are off with the RR and LF being light. I'd bet that your LR and RF adjusters are cranked more than the RR and LF. If this is the case change them (either up with one, down with the other or some of both) so that both fronts have the same number of threads showing. Now do the same with the rear. Note that the front and rear will not show the same number of threads. We want both fronts to match and both rears to match but the fronts won't match the rears. You may wind up with a bit of ride height variance, probably <1/4" but I bet it will solve the uneven braking. I've set the cars I've built up using this method and when scaled they were so close to dead on that they either needed no change or less than 1/4 turn.

Jeff

Jeff,
Thanks for the info, sounds easy enough. Does driver weight 240# undo this balance, or does it need to be done with driver/passenger ?

Rich, I understand, added wt will not change the thread setting, in case you are reaching for the keyboard. LOL

[Jeff Kleiner]

Jeff,
Thanks for the info, sounds easy enough. Does driver weight 240# undo this balance, or does it need to be done with driver/passenger ?

Rich, I understand, added wt will not change the thread setting, in case you are reaching for the keyboard. LOL

In an ideal world the car would be corner weighted with the driver in the seat (unless it one of those new fangled self driving things) but when that isn't possible simply setting the springs as I described in the earlier post will get you pretty darn close.

Jeff

[Rdone585]

There is a lot of good information being shared here, so I'm watching, reading, and learning myself. I have the car corner weighted with salt or sand bags to simulate myself driving. I also have the tech simulate a passenger with extra weight in the passenger seat so I know what the balance will be if I allow a passenger to ride along at the track. Sometimes there is a compromise between the two if I know there will be passengers. I also make sure to have the gas tank between full and 1/2 full of gas. If I plan to run my cool suit I have the cooler mounted and 1/2 full of water. I'm trying to get to the point where I can do this myself in my garage. I have most of the specialized equipment already, just need to find out when I can borrow a set of scales from my friend in the neighborhood.

[Railroad]

Jeff,
My rear spring adjusters were 3 turns different. The front was 1 turn different.
The rear now match side to side, as do the front.
Thanks for the help.

[Jeff Kleiner]

Jeff,
My rear spring adjusters were 3 turns different. The front was 1 turn different.
The rear now match side to side, as do the front.
Thanks for the help.

You had a real good teeter-totter there! I bet your braking will be even now

Jeff