side to side brake balance

I've looked all overt the interwebs and the only place I have found side to side brake balance discussed is some stuff on dirt track racing where L/R balance is manipulated to throw the car sideways into the never ending left handers. Which is sort of my problem.

My 1996 civic hatch has a little d series sitting in the nose. It's placed over to the drivers side with the tranny on the right. I theorize this was because the Japanese engineers wanted to have the car pretty well balanced side to side with a driver in it. But my car is not a JDM Yo right hand drive, it is mexico origin non JDM yo so the steering wheel is on the left. Which is where all 220 lbs of me sits. If I stand on the brakes (99-00 si front and rear disks and master cylinder, hawk hp+ front pads, stock ish rear pads, ate fluid- all of the system is two years old or younger, no ABS).. er, if I stand on the brakes, the front right locks first pretty much every time. I've bled the system a million times, everything works. In the summer on 195 section star specs its not that big a deal, but always present. On all season tires in the wet, it is a ever present pain in the ass.

I am nearly certain that the issue is that when the F/R weight transfer is happening during hard braking, the 220 lb of me coupled with the already heavier left side keeps the left front contact patch pasted to the road while the right has less load and the tire squares into smoke.

I thought this would be a well understood issue. Maybe I'm looking in the wrong places? StopTech's white papers never mention left right bias for instance. Any suggestions appreciated.

I do not have coil overs, I'm on Koni yellows, ebiach sportlines, with front and rear anti sway bars. If Coil overs are the solution I'm willing to do that, but acorrding to information I have read here and elsewhere, the fundamental issue of where the weight is across the chassis will not be addressed with height stagger and is only resolved if I move some weight around. Lots of weight.

Any tips or links to appropriate reading appreciated. I'll buy the right book if its out there.

Thanks!!

http://www.summitracing.com/parts/wil-260-8419/overview/ Cheap experiment? Sounds like you got a pretty well thought out hypothesis.

Have you corner weighed the car?

Does your car have an lsd? I'm not a race engineer but I would think adding one if absent might have a beneficial effect in the front at least.

You might try juggling brake pads with different friction qualities.

In reply to Kenny_McCormic:

I have not corner weighed the car, and that is a priority. Amazingly, I had not thought of putting a valve on a single line- thanks! My concern would be that I put it in the right place:

after the OEM proportioning valve on the line to the left front?

Before the OEM porportioning valve on the feft front/right rear circuit?

I would imagine the left front by its self as a first stab. I am also going to make sure I am on the right track and buy 3-4 bags of river 50lb (or whatever they are) river stone bags and put various numbers of them in the passenger front foot-well and see what that does. And there is a generally abandoned but functioning 24/7 truck scale near me that I will go get rough corner weight numbers from.

Kenny_McCormic wrote: Have you corner weighed the car?

This.

with just me in it, a bunch of fishing gear in the back, 1 gallon of gas, and a 10 lb Coho Salmon (dead) in a cooler:

front of car on scale 1650 left front on scale 850
right front on scale 800 left rear on scale 600 right rear on scale 500

left wheels on scale1350

right wheels on scale1250

Whole car on scale 2650

the scale rounds to a 50. nearest 50? biased up? biased down? I don't know how the state jiggers the scales. But anyway the left side of the car is 150lbs (+ or - 50 ish) heavier than the right. Makes sense. Obviously I used a blunt tool, but still...

Is this sort of weight spread commonly closed with coil-overs? Or does one need to move/re move mass as well?

I'll follow though with the river stone in the passenger foot-well experiment side to side brake bias adjustment.

In reply to Shaun:

Its only locking the left front prematurely so put it on the left front post prop valve.

I wouldn't recommend trying to bias the whole diagonal anyhow, tends to make the car a bit darty one way or the other, at least in the extreme case of the circuit blowing out mid panic stop on the highway (don't ask how I learned this).

Get the car on a set of decent scales to check the corner weights. That should resolve the issue. If this does not resolve the issue, check for issues with the front calipers sticking or brake lines pinched, etc.

Please, never install a prop valve in the front brake system- no good can come from that.

Those corner weights aren't horrible.

I would NOT try to change the pressure to a particular corner. Furthermore, those valves would not decrease the pressure. They would decrease the time it takes the pressure to build. Eventually, you would end up at the same pressure.

I would be looking at the alignment before I did anything else. I would bet you have slightly more camber on that side than the other side.

Rob R.

In reply to wvumtnbkr:

The car has been aligned by a race oriented shop, A&K, here in Portland who do a really good job. the toe is 0 on all corners and the camber matches side to side (I would need to find the sheet). The car does not pull at all while braking. But that is a thought.

Good info on the prop valve.

devina wrote: Get the car on a set of decent scales to check the corner weights. That should resolve the issue. If this does not resolve the issue, check for issues with the front calipers sticking or brake lines pinched, etc. Please, never install a prop valve in the front brake system- no good can come from that.

Why would checking the corner weight change anything. After I checked them last night the car behaved in exactly tje same manner as before I checked them.

No good can come from allot of things I do regularly. Why is a prop valve a problem on a single side?

iceracer wrote: You might try juggling brake pads with different friction qualities.

You could definitely try to adjust the lock up with different pad compounds L to R on the front axle. This would be reasonably simple and cheap. Plus you get tow sets of pads from the experiment, if you chose the right compounds.
Some have said not to try a proportioning valve on a single front line, but I have seen it in some very fast oval track cars.
Another option is to see about a caliper with smaller pistons for the RF. Like the different pad compounds, this may be a good solution, but you will have to work out some numbers to get the L/R balance where you want it.

The biggest issue with trying to adjust with compound or caliper size is the temperature variation may throw the balance off more with cold brakes, but be spot on with hot brakes.

stafford1500 wrote:

iceracer wrote: You might try juggling brake pads with different friction qualities.

The biggest issue with trying to adjust with compound or caliper size is the temperature variation may throw the balance off more with cold brakes, but be spot on with hot brakes.

Or be spot on cold and different hot. I share your concern with your suggestion in that I do not want to open a huge bag of worms and different compounds could well do that. I found an article in which a set of pads were ground in steps removing surface area and the braking forces measured against a control. But even that would change the temperatures and the compounds working characteristics side to side.

In a brief tour of the interwebs I found that 'proportioning valve' is a very broad category of hydraulic system component. Some are threshold gated and reduce pressure, like the front rear OEM proportioning valve in the car now, and some only reduce pressure- like the Willwood piece. And some are much more complicated.

My next step is 220 lbs of river stones in the F/R passenger footwells. The scale apron has plenty of room for safe experimenting with threshold braking.

It might be a couple days...

200lbs of river rock in the passenger side (2 in front footwell, two in rear foot-well) completely solved the problem. I'll order the Ground Controll coil overs with the Eibach springs and bump the front rate by 100 lbs and get it set up using proper scales. I'm curious to see if if this issue can be resolved with spring heights. Me thinks not, but I think it will be improved. I'm intrigued by the prop valve on the left front idea and will try it if need be, thanks Kenny.

I found a Honda video where they stated that they went for even L/R balance in their home market with a 160 lb driver weight on board.

I think ABS masks this issue for allot of folks.