"Direct Connection" knob

[trcunni]

I just bought a CCX that has a "direct connection" knob on the trans tunnel. According to the diagram on the knob, rotating clockwise increases something, and rotating it counterclockwise decreases something. What is this???

[MKS427]

For now, it there to modulate your curiosity. LOL
It may be an adjustable brake proportioning valve. Check and see if it is connected to brake lines.

https://www.forabodiesonly.com/mopar...-valve.389010/

[ERA 626]

Brake Bias, This is often used while racing if the track conditions change. For street use set it and leave it. I race Shifter Karts, we often use the brake bias on different tracks. I will do several hot laps and let the tries and brakes come up to temperature. Then coming into the pits (in a safe place) I will stand on the brakes. This will tell me several things, does it pull to one side? (air in one caliper) or does the rear lock up? does the front lock up? (bad)
To test it go to a safe place! do a HARD brake at about 20mph. Experience what the car does, does the rear lock up early and cause a spin? or does the front lock up? If it is set up correctly you should have a little more rear bias then front. If the fronts lock up, this will do bad things while heavy braking coming into a turn.

All this knob does is restrict the amount of fluid passing through it ie proportioning valve (brake bias)

[xb-60]

Originally Posted by ERA 626

....To test it go to a safe place! ....If the fronts lock up, this will do bad things while heavy braking coming into a turn....

Good advice to do a brake test in a safe location to see how the car behaves.

However....if you set the bias for the rears to lock up first, that would certainly "do bad things while heavy braking coming into a turn"

I would have the fronts locking up slightly ahead of the rears.

Happy driving!
Glen


edit: doesn't that symbol look like a Chrysler Pentastar logo....?

[Alfa02]

Yep, Glen that's Chrysler's Hi-Po shop "Direct Connection" Mopar stuff on a Ford Hummmm...... Cheers TommyRot. P.S. Yes, with the rest of the boy's I would say Brake-Bias.

[ERA 626]

Originally Posted by xb-60

Good advice to do a brake test in a safe location to see how the car behaves.

However....if you set the bias for the rears to lock up first, that would certainly "do bad things while heavy braking coming into a turn"

I would have the fronts locking up slightly ahead of the rears.

Happy driving!
Glen


edit: doesn't that symbol look like a Chrysler Pentastar logo....?

Happy to disagree here, if the fronts lock up before the rears, this will put you into a spin that you will not be able to control. If you have slightly more rear bias it will be controllable. The shifter kart is very much like a cobra in a sence that the cobra has suspension the kart does not... Kart racing is the purest form of racing... Love it, live it, do it... If you have never had the experience of 60+ 125cc shifter karts hitting turn 2 at luguna seca doing 100+ MPH at the same time , you need to try it one day... that my friend is racing. Brake bias is a topic that all of us discuss on a regular basis. Trust me I have tried more front bias with bad results, I would rather have no front brakes than more front bias all day long. In fact the 80cc formula class does not allow front brakes.

[Alfa02]

With a car or kart, you Never use more rear brake-bias. Example: Your running 150+mph, down the straight, coming in a turn, what is the Car (Kart) going to do during braking? Transfer all that weigh to the front wheel's Where you need more brake's, the rears now has less weigh (ie) less traction, less brake. It also work's in the opposite direction, That's why you don't see any Front Wheel Drive Top Fuel Dragster's. Simple science. Trust me kids, I do know a little about this stuff, I've raced sports cars for 40+years , and Two Time National Champion, with a FF (Formula Ford), (GT-2 RX-3), 240Z, and Mazda Rx-7. P.S. Never lock up your tires (No steering, or control) Cheers TommyRot.

[xb-60]

Originally Posted by ERA 626

Happy to disagree here, if the fronts lock up before the rears, this will put you into a spin that you will not be able to control. If you have slightly more rear bias it will be controllable. The shifter kart is very much like a cobra in a sence that the cobra has suspension the kart does not... Kart racing is the purest form of racing... Love it, live it, do it... If you have never had the experience of 60+ 125cc shifter karts hitting turn 2 at luguna seca doing 100+ MPH at the same time , you need to try it one day... that my friend is racing. Brake bias is a topic that all of us discuss on a regular basis. Trust me I have tried more front bias with bad results, I would rather have no front brakes than more front bias all day long. In fact the 80cc formula class does not allow front brakes.

Hi Mike,

I'm a little too long in the tooth now to try 100+ mph in a kart, so I can't argue with any authority about brake balance on a modern kart. My karting experience is limited to a home-built kart with rear axle braking only, raced on dirt tracks on my family's property. Kart slicks....wet track....great fun!
So...I'll defer to your experience in fast karts, but I still prefer front brake bias on a road car.

Cheers!
Glen

[Tom Wells]

I'm tempted to say, after looking at this statement:

if the fronts lock up before the rears, this will put you into a spin that you will not be able to control

that this is bass-ackwards from what an average race car will do.

Perhaps with karts this opposite behavior does happen; Experience says that with a race car on a road race track, locking the fronts will not cause a spin, but quite the opposite: the car will basically go straight ahead and understeer right off the racing surface. This is when your braking is being done in more or less a straight line before you begin turning in. If you are braking while turning, you earn whatever happens (unless practicing trail braking, see below.)

If the rears lock first, it is similar to trying to stop an arrow with one finger on its tip. The slightest deviation from straight ahead will result in a snap spin. Same with the car - if a lockup occurs at the rear, you lose the ability to steer and become a passenger!

It's kinda the difference between hitting the wall with the front or the rear of the car - neither is usually good for the car or the driver.

I set my brakes to have the fronts lock a bit before the rears - at least you can steer a little with the fronts locked. Not so if the rears lock.

There is a technique known as "trail braking" where you use the brakes to partially unload the rear tires to assist the car rotating into the entry of a corner. If you're doing this, your driving skills are way beyond mine!

Hope this helps,

Tom

[legenmetals]

I race shifter karts also, lock up the rears and the rear of the kart will want to swap place with the front of the kart.

[ERA 626]

Originally Posted by Tom Wells

I'm tempted to say, after looking at this statement: that this is bass-ackwards from what an average race car will do.

Perhaps with karts this opposite behavior does happen; Experience says that with a race car on a road race track, locking the fronts will not cause a spin, but quite the opposite: the car will basically go straight ahead and understeer right off the racing surface. This is when your braking is being done in more or less a straight line before you begin turning in. If you are braking while turning, you earn whatever happens (unless practicing trail braking, see below.)

If the rears lock first, it is similar to trying to stop an arrow with one finger on its tip. The slightest deviation from straight ahead will result in a snap spin. Same with the car - if a lockup occurs at the rear, you lose the ability to steer and become a passenger!

It's kinda the difference between hitting the wall with the front or the rear of the car - neither is usually good for the car or the driver.

I set my brakes to have the fronts lock a bit before the rears - at least you can steer a little with the fronts locked. Not so if the rears lock.

There is a technique known as "trail braking" where you use the brakes to partially unload the rear tires to assist the car rotating into the entry of a corner. If you're doing this, your driving skills are way beyond mine!

Hope this helps,

Tom

Trail Braking THANK YOU bingo... I am 2 time Road Race Champion IN Northern California Karters (NCK) 125cc stock moto class, our biggest most competitive class.
I think we need to agree to dis agree here, I cant speak much for racing a 2400 lb Cobra, however I can safely say I have been around a road race Track on a 110mph Shifter kart 1000+ times. (Laguna Seca, Sears Point, Button Willow, Thunder Hill, Willow Springs, just to name a few. I acknowledge that more rear bias in needed on Thunder Hill west (2 mile track)than Thunder main (3mile track) and a LOT more on a sprint track like sonoma Kart Track, Dixon, Hang Town etc...

I do need to say that Sprint racing is a lot different that Road Racing. On a short tight technical track more rear Bias works better, too much front bias will literally lift the ass end off the ground and cause a violent spin that you will not recover from. But on a Road Race track we tend to adjust per track conditions, the amount of rubber on the track, the temp, tire pressures , chassis tune all come into play while adjusting brake bias. Hence the entire reason for this "mystery knob" that started this thread in the first place.
Bottom Line is every Car or Kart is different, different driving styles, different track conditions all come into play, so perhaps there is no real correct answer here.

[Morris]

Originally Posted by ERA 626

All this knob does is restrict the amount of fluid passing through it ie proportioning valve (brake bias)

This is not Correct...

The Proportioning Valve is a pass Thru body with a ball and spring inside the housing. As the knob is screwed all the way in...fully clockwise....the spring and ball is compressed in the body of the Proportioning Valve. Therefore, as you put your foot on the brake pedal and increase pressure in the brake line .... the pressure goes thru the proportion valve and to the caliper at the same pressure that came into the proportion valve.

If you back out the proportion valve to the minimum setting... as you apply pressure to the brakes the input pressure is the same as before, but, with the spring and ball backed out to the minimum setting, the pressure will go to the caliper and then the spring and ball will forced up into the proportion valve body and this fluctuation will reduce the pressure to the caliper.

The ration of input to output is from 1:1 to 1:3 so that the pressure applied to the caliper is reduced as the pressure goes up because the spring and ball in the proportion valve flex as you apply more pressure.

You can never get more pressure out of a Proportional Valve, however, a Proportion Valve and a Balance Bar can fine tune a brake system to assist in making the car tune-in better as needed on various tracks.

We've been running both items for years and use the Balance Bar as the course adjustment and the Proportion Valve as a Fine tune adjustment.

[Morris]

In regards to how do you balance your brakes??

The proper way to balance your brakes without sensors is to use Brake Paint.
The brake paint comes in different temperatures, so you sand the edge of the rotor down and paint a H pattern on the rotor. Starting at the top with 1200*degree paint then next to the 1200*degree paint, you paint another H pattern on the rotor that is 1100*degrees and you do the same for 1000* and 900*degrees.

When you come off the track, then you put the car up in the air and remove the wheels and rotate the rotor so the 1200* paint is up at the top and then you can see how much heat got into the rotor as the lower degrees will be burnt off and the 1200*degree will be left on the rotor....

Most of the time our rotors ran between 1200*degrees on the front and 1100*degree in the rear. on a track that didn't have the demand for brakes as others ... the temps would drop down to 1100*degrees Front & 1000* Rear.

And yes sometimes we used rear bias to help the turn in on the front of the car.









Hope that helps

[Morris]

PS. You should never lock up your brakes at anytime on a racetrack...Any time you loose adhesion between the track and the tires is bad and Bad things will happen...

So make sure your brakes are bedded in correctly and "Smooth is Fast"

[1795]

Originally Posted by Morris

PS. You should never lock up your brakes at anytime on a racetrack...Any time you loose adhesion between the track and the tires is bad and Bad things will happen...

So make sure your brakes are bedded in correctly and "Smooth is Fast"

Morris,

Thanks for your input. Was hoping that you would find your way to this thread, and yes, I agree with you 100% that you do not want to lockup your brakes on the track. Only bad things can come of it. If something is so bad ahead that you think that you need to lock the brakes to avoid a collision, it's time for a controlled spin.

Jim

[Alfa02]

Late "Trail Braking" actually is the last act you do with braking. After you have done your braking in a straight line, coming a corner, your using your turn-in (Steering) to induce a "touch" of oversteer, to help rotate, while still unloading the rear of the car. Again done in one smooth motion, releasing the brakes, as adding throttle, It's the last part of the act of Heel & Toeing. It takes LOTS of Practice, but done right, makes a smooth & quicker exit. Understeering (most street cars), and Front wheel drive cars use this technique to help rotate the car. Hope I explained this well enough to understand Cheers Tom.

[Tom Wells]

Another aspect of handling, especially in a Cobra, is "trailing throttle oversteer" AKA "TTO."

If you want to experience this, it's way too easy

As you start to turn in to a corner, if you still have a bit of throttle applied, let off the gas suddenly. The tail will predictably snap around immediately, throwing you instantly into a spin.

Needless to say, try this where there isn't anything stationary for you to spin into, like a (truly) deserted parking lot.

Driving schools like for you to experience this under their watchful eye so you know a little something about what not to do.

A real life circumstance where this occurs can be a freeway entrance or exit. If you come into it a little too hot, and "snap" the throttle shut, well, you are either real lucky in the ensuing two seconds, or you get to experience collision insurance stress - the typical Cobra TTO spin will happen faster than most humans can react.

All in a good day's fun! Be careful...

Tom

[1985 CCX]

https://www.speedwaymotors.com/Wilwo...%20(Feb28_2020)