Pad Knockback

[turbosax2]

If I were to remove the abs, these are the two setups I can choose from. Do these diagrams look right?

Dual APV

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[underradar92]

If I'd have known that type valve existed, I'd have given more thought to leaving the system configured diagonally. Uneven adjustment potential is one of the main reasons I didn't, it is safer set up diagonally.

The top diagram should criss-cross the lines to one end or the other, the way it's drawn, if a failure occured, the car would spin, as both wheels on one side would be trying to stop that side of the car.

 

[turbosax2]

If I'd have known that type valve existed, I'd have given more thought to leaving the system configured diagonally. Uneven adjustment potential is one of the main reasons I didn't, it is safer set up diagonally.

The top diagram should criss-cross the lines to one end or the other, the way it's drawn, if a failure occured, the car would spin, as both wheels on one side would be trying to stop that side of the car.

Woops I'll fix that now.

Like you said, having 2 apv's doesn't sound like a smart idea considering they could have slight differences between the units that wouldn't provide even pressure to the rears. Or, the user could just be dumb enough to put them at different settings But I would like to keep the diagonal setup for obvious safety reasons, so I think the dual apv is the superior setup.

Any 2g racers out there - come on in and share your thoughts on the 2g abs system!!!

 

[turbosax2]

Ok, I edited my diagonal diagram. Is that correct now?

 

[underradar92]

Looks fixed to me.

 

[absolute_DSM]

I wasnt even aware there was a dual valve like that. Thats a good find.

 

[turbosax2]

I wasnt even aware there was a dual valve like that. Thats a good find.

Well, maybe not. I've been trying to find more info on this valve and there's not much out there. But from what I have found, it seems like it has 2 inputs and 2 outputs, but I think only one of the outputs is controlled by the apv portion. What do you guys think?

eBay Motors: SSBC Adjustable Proportioning Valve Polished- Block (item 260213417684 end time Feb-26-08 13:44:08 PST)
eBay Motors: SSBC A0730 Adjustable Proportioning Block Assembly (item 250155880807 end time Mar-14-08 15:09:16 PDT)
eBay Motors: Brake Adjustable Proportioning Valve Block (item 140171800062 end time Mar-22-08 09:29:50 PDT)
http://www.mustangdepot.com/OnLineCatalog/images/Brakes/a0730.jpg

 

[turbosax2]

I found a better description here. It has 5 ports - 1 front inlet (from master cylinder), 1 rear inlet (from master cylinder), 1 pass. front outlet, 1 driver front outlet, and 1 rear outlet. So it's just a tee and an apv in one unit. It does the same thing my F/R diagram does, just with more money and more hose.

So that won't do what I want it do.

 

[schemauer]

Keep the ABS - it was removed on my track car and I've flatspotted a few tires without it. It's no fun replacing brand new tires from locking them up.

I'm trying to understand some of the discussion on prop valves above........ I think what you want is a system that proportions the front and rear separately, allowing you to dial in more rear brake if needed. Also a system that will allow ABS to engage for the fronts, but not the rears - and vice versa......

 

[underradar92]

After more thought, imagine going into a fast corner at threshold braking. A rear wheel lifts, (super common on our cars, FWD & AWD alike) the opposite front stops braking, since its paired rear is now stopped, hello tire wall. Scott, this happens on your car all the time, seriously, the OEM ABS will not be your friend.

The slow recovering, 2 channel deal would create more problems than it helps on a road course, IMNHO.

 

[Slow old poop]

After more thought, imagine going into a fast corner at threshold braking. A rear wheel lifts, (super common on our cars, FWD & AWD alike) the opposite front stops braking, since its paired rear is now stopped, hello tire wall. Scott, this happens on your car all the time, seriously, the OEM ABS will not be your friend.

The slow recovering, 2 channel deal would create more problems than it helps on a road course, IMNHO.

In a AWD car, you should do all your braking in a straight line, lift, turn in, and accelerate through the apex. If a wheel comes up, it does it under acceleration and g-forces through the turn, not from braking. I can't imagine any turn at Road America (where we saw Scott's wheel lift) where you would be braking deep and turning at the same time. Of course, Scott has a FWD car, so I don't know if that's true with his car. His car is so stiff and so light in the back, the rear wheels probably come up if you stare too hard at them. Scott: What say ye?

 

[mavisky]

Mine hikes its leg like a dog who drank a gallon of water and has been running for the last hour only to end up right next to its favorite fire hydrant.

 

[Slow old poop]

Mine hikes its leg like a dog who drank a gallon of water and has been running for the last hour only to end up right next to its favorite fire hydrant.

Under braking?

 

[underradar92]

In a AWD car, you should do all your braking in a straight line, lift, turn in, and accelerate through the apex. (we saw Scott's wheel lift) His car is so stiff and so light in the back, the rear wheels probably come up if you stare too hard at them.

I'm a sucky driver so I sometimes have to make a steering correction under braking. My car is nearly as nose heavy as FWD's are (60/40), the saving grace of AWD is setup, as FWDs are usually way stiff in the rear to avoid incessant understeer, hence more noticeable rear tricycling. I would hate to find out the hard way that the rear is unloaded to the point where bumps in the braking zone allow the rears to slow/stop momentarily and do the ABS shuffle. Having the adj. prop. valve allows me to actually use those tiny rear brakes, so i believe it is already happening.

Ever see an EVOVIII in a turn? Luckily they have a good, fast 4 channel ABS. Maybe someone should adapt one?

 

[mavisky]

Under braking?

Under trail braking, but not straight line.

 

[drivemusicnow]

First, When looking at the iowa speedway picture, it seems much more likely that the strut towers would bend causing some of the loss in camber that SlowOldPoop is seeing, the other half of course coming from camber gain due to McPherson strut design.

Now for pad knockback: I found this super awesome article Here Unfortunately it states all the same conclusions that have already been made.

It's definitely worth a read though as it talks about how pad knockback is a function of both rotor diameter and fixed caliper design.

Seems like fresh wheel bearings, proper torques, and pressurevalve/springs seem like the easiest way to get rid of most of it.

If you want to go further, new (unfatigued) spindles and larger diameter master cylinders (would move more fluid with less stroke) would seem to be the best ways to go. Tilton makes a 1.125" MC that might be able to be used. It's only 70$ so it might be something to try.

Does anyone sell a proportional master cylinder that pushes more fluid at first, and less after a certain pedal input? Isn't the brake booster supposed to do this in part?


As far as the ABS system goes the 1g's ABS is really not worth keeping. I wanted to at first, but it's performance, or lack thereof, and my inability to replace wheel bearings without removing the spindle/wheel bearing was enough reason for me to axe mine.

I'm actually pretty surprised that no company has tried to offer aftermarket ABS options. You would think that a computer controlled ABS system wouldn't be all that difficult to make, as long as the setup was done properly. offer it as a "plumb it yourself" system, with laptop control that is locked unless you agree that the company is not liable. Have proprietary wheel speed sensors that can be mounted in a variety of ways... I know there is a lot that goes into ABS optimization, but you would think there are a few very similar needs for track cars. Anywho, enough of my crazy ideas.

 

[Slow old poop]

First, When looking at the iowa speedway picture, it seems much more likely that the strut towers would bend causing some of the loss in camber that SlowOldPoop is seeing, the other half of course coming from camber gain due to McPherson strut design.

Just in case anyone was wondering, yes, I had a front strut brace. Our next step was going to be poly bushings (if I had kept the car) to eliminate more movement in the suspension.

Elvenhome also suggested fabbing up camber plates that allowed more caster. He gave me a complicated explanation (which made sense at the time) about how more caster would alter the suspension geometry and provide more "stick" at the front. Alas, no one makes camber plates that permit a caster adjustment, so you gotta cut off the tops of the strut towers and fab something up.