Tilton brake bias valve incompatible with ABS ?
04-28-2012, 02:01 PM
#61
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@ApexComp - regarding the brake activation exiting the corner - are you saying you can hear (or feel) the pump motor run and/or valves activate? If so, and you're not on the brakes... just how sure are you that don't in fact have an ABD or TCS ECU?
Actually - it'll be easy to spot that if you can send another pic of the ABS unit, like your first, only showing the face that faces the front of the car - parallel to the bolts holding the ECU to the HU (hydraulic unit). The ABS-only unit is noticeably smaller due to the lack of extra valves required to build pressure. Should be relatively easy to spot in a photo from the right angle, if you can get in there.
I do hope you're not running into some early caliper compliance/knockback stuff - but I'd be surprised that a Porsche would need that, and also that it would've existed back in 5.3.
Again, a pic will show for a fact if the unit's even capable of build pressure without brake pedal apply.
04-28-2012, 03:31 PM
#62
Three Wheelin'
Thread Starter
Stock is 0.9% with 265/30-R18 & 225/40-R18.
I'd heard somewhere that the difference should be kept under about 3% but I know the Spec 996 guys are running 285/30-R18 and 245/40-R18 or 4% difference without ABS/TC issues.
I'd heard somewhere that the difference should be kept under about 3% but I know the Spec 996 guys are running 285/30-R18 and 245/40-R18 or 4% difference without ABS/TC issues.
04-28-2012, 04:01 PM
#63
Pro
I'm not sure. I only know what I read. Supposedly I only have 3-channel ABS because I only have 3 output lines from the ABS block. As shown in the schematic I posted. And 3-channel should mean no-TC and no-ABD according to Porsche docs. I also have no TC switch on the dash and no TC light in the gauge cluster.
2 lines in from the 2 MC ports
V / H (Vorn und Hinten)
3 lines out from the ABS block
VL, VR, H
Vorn Links, Vorn Rechts and Hinten
2 lines in from the 2 MC ports
V / H (Vorn und Hinten)
3 lines out from the ABS block
VL, VR, H
Vorn Links, Vorn Rechts and Hinten
04-29-2012, 09:25 AM
#64
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Actually, it depends on the exact system they're running; some algorithms are more tolerant, some will just throw lights. And of course there's always the possibility of underbraking an axle if the wheel speeds aren't properly compensated front/rear. Most people only pay attention to if TCS is too intrusive...
@ ApexComp - yeah, that definitely looks just like an ABS-only HU, so there should be no way it can generate any pressure at the wheel outside of what you yourself make with the pedal, regardless of what kind of algorithm you try and stuff on those chips.
04-29-2012, 10:21 AM
#65
Three Wheelin'
Thread Starter
As far as they know... LOL
Actually, it depends on the exact system they're running; some algorithms are more tolerant, some will just throw lights. And of course there's always the possibility of underbraking an axle if the wheel speeds aren't properly compensated front/rear. Most people only pay attention to if TCS is too intrusive...
Actually, it depends on the exact system they're running; some algorithms are more tolerant, some will just throw lights. And of course there's always the possibility of underbraking an axle if the wheel speeds aren't properly compensated front/rear. Most people only pay attention to if TCS is too intrusive...
Now I'm more inclined to try a 245/40 up front as well albeit with a 295/30 rear.
04-29-2012, 02:12 PM
#66
Pro
Since we are on the topic of Bosch 5.3 ABS brakes.... thought I'd toss this out there
Some ABS devices have their own internal reservoirs (Bosch ABS5.3, for example) that are not a part of the primary brake circuit and are only opened to the rest of the circuit when the ABS is active. If you bled your system and never again cycled your ABS, you would be fine. However, as soon as the ABS cycled - even for a few tenths of a second - the "old" fluid (which was never bled because it was hidden) would be dumped into the primary circuit.
Solution:
The end result takes a little more time than a conventional bleed, and requires you use a little more fluid, but looks like this:
Step 1 - Manually bleed RR, LR, RF, LF brakes
Step 2 - Install service tool and cycle all valves and/or pumps
Step 2 for the rest of us: Drive car. Find sandy/gravel area and stomp on the brakes a few times to activate ABS.
Step 3 - Manually bleed RR, LR, RF, and LF brakes again
You end up having bled the system twice, but this is necessary to ensure that fresh fluid - and NOT used fluid - is drawn into the unit the next time that the ABS valves (and/or pump) are cycled.
This is only necessary when flushing the ENTIRE system. It's not needed to do your standard caliper bleeding as you would prior to a track day.
Source: http://www.stoptech.com/technical-su...-brake-systems
Some ABS devices have their own internal reservoirs (Bosch ABS5.3, for example) that are not a part of the primary brake circuit and are only opened to the rest of the circuit when the ABS is active. If you bled your system and never again cycled your ABS, you would be fine. However, as soon as the ABS cycled - even for a few tenths of a second - the "old" fluid (which was never bled because it was hidden) would be dumped into the primary circuit.
Solution:
The end result takes a little more time than a conventional bleed, and requires you use a little more fluid, but looks like this:
Step 1 - Manually bleed RR, LR, RF, LF brakes
Step 2 - Install service tool and cycle all valves and/or pumps
Step 2 for the rest of us: Drive car. Find sandy/gravel area and stomp on the brakes a few times to activate ABS.
Step 3 - Manually bleed RR, LR, RF, and LF brakes again
You end up having bled the system twice, but this is necessary to ensure that fresh fluid - and NOT used fluid - is drawn into the unit the next time that the ABS valves (and/or pump) are cycled.
This is only necessary when flushing the ENTIRE system. It's not needed to do your standard caliper bleeding as you would prior to a track day.
Source: http://www.stoptech.com/technical-su...-brake-systems
04-29-2012, 02:27 PM
#67
Pro
Photo of completed Tilton installation....
However after some pressure testing I'm not at all confident that the 3/16 (M10) lines are safe. They dont allow a large enough "bubble" to be formed and therefore don't seat well even with the M12 fittings. I experienced some leakage even after re-making the flares a few times.
I need to do this with "1/4" brake lines (as Porsche did) to get the correct size bubble flare on the ends that seat into the MC & ABS block. So I'm back to looking for M10(male) to M12 (female) line adapters. I will mount the adapters on the Tilton adjuster and run 1/4 lines between M12x1 fittings. So if anyone knows where I can find M10x1(m) to M12x1(f) fittings please let me know.
I've found pipe thread adapters but not brass brake line fitting adapters (with tapered seats).
However after some pressure testing I'm not at all confident that the 3/16 (M10) lines are safe. They dont allow a large enough "bubble" to be formed and therefore don't seat well even with the M12 fittings. I experienced some leakage even after re-making the flares a few times.
I need to do this with "1/4" brake lines (as Porsche did) to get the correct size bubble flare on the ends that seat into the MC & ABS block. So I'm back to looking for M10(male) to M12 (female) line adapters. I will mount the adapters on the Tilton adjuster and run 1/4 lines between M12x1 fittings. So if anyone knows where I can find M10x1(m) to M12x1(f) fittings please let me know.
I've found pipe thread adapters but not brass brake line fitting adapters (with tapered seats).
04-29-2012, 03:00 PM
#68
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Since we are on the topic of Bosch 5.3 ABS brakes.... thought I'd toss this out there
Some ABS devices have their own internal reservoirs (Bosch ABS5.3, for example) that are not a part of the primary brake circuit and are only opened to the rest of the circuit when the ABS is active. If you bled your system and never again cycled your ABS, you would be fine. However, as soon as the ABS cycled - even for a few tenths of a second - the "old" fluid (which was never bled because it was hidden) would be dumped into the primary circuit.
Solution:
The end result takes a little more time than a conventional bleed, and requires you use a little more fluid, but looks like this:
Step 1 - Manually bleed RR, LR, RF, LF brakes
Step 2 - Install service tool and cycle all valves and/or pumps
Step 2 for the rest of us: Drive car. Find sandy/gravel area and stomp on the brakes a few times to activate ABS.
Step 3 - Manually bleed RR, LR, RF, and LF brakes again
You end up having bled the system twice, but this is necessary to ensure that fresh fluid - and NOT used fluid - is drawn into the unit the next time that the ABS valves (and/or pump) are cycled.
This is only necessary when flushing the ENTIRE system. It's not needed to do your standard caliper bleeding as you would prior to a track day.
Source: http://www.stoptech.com/technical-su...-brake-systems
Some ABS devices have their own internal reservoirs (Bosch ABS5.3, for example) that are not a part of the primary brake circuit and are only opened to the rest of the circuit when the ABS is active. If you bled your system and never again cycled your ABS, you would be fine. However, as soon as the ABS cycled - even for a few tenths of a second - the "old" fluid (which was never bled because it was hidden) would be dumped into the primary circuit.
Solution:
The end result takes a little more time than a conventional bleed, and requires you use a little more fluid, but looks like this:
Step 1 - Manually bleed RR, LR, RF, LF brakes
Step 2 - Install service tool and cycle all valves and/or pumps
Step 2 for the rest of us: Drive car. Find sandy/gravel area and stomp on the brakes a few times to activate ABS.
Step 3 - Manually bleed RR, LR, RF, and LF brakes again
You end up having bled the system twice, but this is necessary to ensure that fresh fluid - and NOT used fluid - is drawn into the unit the next time that the ABS valves (and/or pump) are cycled.
This is only necessary when flushing the ENTIRE system. It's not needed to do your standard caliper bleeding as you would prior to a track day.
Source: http://www.stoptech.com/technical-su...-brake-systems
Of course, it's open for discussion just how much water you think might exist in the two 3 or 5cc accumulators, and how much impact, diluted in your entire brake system, that may have to pedal feel/boiling...
Personally... I don't even really think it's much worth worrying 'bout.
04-29-2012, 09:57 PM
#69
Rennlist Member
i have durametric enthusiast version and it allows to cycle ABS pumps during bleeding.
http://www.planet-9.com/reviews/elec...functions.html
ps. but to get all air out after master cylinder upgrade took 3 liter worth of fluid total with ABS cycles in durametric and then driving with ABS activation and then bleed again with pumping brake pedal and power bleeder at same time. some air pockets are very difficult to get rid of.
http://www.planet-9.com/reviews/elec...functions.html
ps. but to get all air out after master cylinder upgrade took 3 liter worth of fluid total with ABS cycles in durametric and then driving with ABS activation and then bleed again with pumping brake pedal and power bleeder at same time. some air pockets are very difficult to get rid of.
05-18-2012, 11:25 AM
#70
Pro
Watkins Glen braking update
So.... just got back from 3 perfect days at Watkins Glen. Was running with the our local PCA club. I love this track. Have many laps here from my racing days and was very happy to get down into the 2:14s with the old girl 
Here are a couple videos...
"Club Sport 996 @ Watkins Glen
Longer and with more comments
So what did I learn? I learned that on a longer track with sufficient time to cool the brakes in between corners that there is nothing "really" wrong with my brakes.
I ran the ABS & no bias adjustment and the same aggressive CL RC 6E pads and had absolutely no issues. I could feel the brakes getting just a bit soft on occasion and I was still generating a LOT of heat but they never "failed" like they do at Beaverun.
So, my conclusion is that I was over thinking the issue due to the track I always run at. Beaverun is a "point and squirt" track where you brake hard in 2 locations and then use the brakes in quick succession for half the lap, which never gives them time to cool. This is obviously resulting in heat soak & possible fluid boiling (although I didn't get air when bleeding). At WGI however I was able to cool the brakes on the long runs in between corners. Also, most of the corners at WGI are not "stand it on its nose" type of corners.
I'm going to look into additional cooling ducts for the car when I run at Beaverun (now Pittsburgh International Race Complex, or PIRC)
Only 2 things were changed from my previous tests. 1 was a complete flush of the system including ABS internal reservoir and replacement with a slightly higher boiling point fluid. I went with Motul RB600 instead of the ATE Super Blue. I think it's only about 40* higher. However every bit helps.
The other change was the addition of brake temp paint. I put it on the back of the pads, the rotors and a few other places. According to the color change I'm peaking about ~900-1000 degrees F on the rotors and pads.
No other components seem to be over 600*F however.
I purchased an OE GT3 brake line that replaces the restrictor to the rear brakes. May give this a test during the next track day to see if additional rear pressure improves the overall balance. It does seem as if I still have more front bias than would be optimal but I really have no hard data to support this.
Here are a couple videos..."Club Sport 996 @ Watkins Glen
Longer and with more comments
So what did I learn? I learned that on a longer track with sufficient time to cool the brakes in between corners that there is nothing "really" wrong with my brakes.
I ran the ABS & no bias adjustment and the same aggressive CL RC 6E pads and had absolutely no issues. I could feel the brakes getting just a bit soft on occasion and I was still generating a LOT of heat but they never "failed" like they do at Beaverun.
So, my conclusion is that I was over thinking the issue due to the track I always run at. Beaverun is a "point and squirt" track where you brake hard in 2 locations and then use the brakes in quick succession for half the lap, which never gives them time to cool. This is obviously resulting in heat soak & possible fluid boiling (although I didn't get air when bleeding). At WGI however I was able to cool the brakes on the long runs in between corners. Also, most of the corners at WGI are not "stand it on its nose" type of corners.
I'm going to look into additional cooling ducts for the car when I run at Beaverun (now Pittsburgh International Race Complex, or PIRC)
Only 2 things were changed from my previous tests. 1 was a complete flush of the system including ABS internal reservoir and replacement with a slightly higher boiling point fluid. I went with Motul RB600 instead of the ATE Super Blue. I think it's only about 40* higher. However every bit helps.
The other change was the addition of brake temp paint. I put it on the back of the pads, the rotors and a few other places. According to the color change I'm peaking about ~900-1000 degrees F on the rotors and pads.
No other components seem to be over 600*F however.
I purchased an OE GT3 brake line that replaces the restrictor to the rear brakes. May give this a test during the next track day to see if additional rear pressure improves the overall balance. It does seem as if I still have more front bias than would be optimal but I really have no hard data to support this.
05-18-2012, 04:20 PM
#71
Pro
ABS
245/35-18 24.7" dia
315/30-18 25.7" dia
PS - The Goodyear RS is an awesome tire! Lighter, arguably faster and $20 less than the R6.
05-19-2012, 08:54 AM
#72
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Rennlist Member
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Good to know, thanks for posting back, Bill!
05-23-2012, 04:06 AM
#73
Three Wheelin'
Thread Starter
I ran the ABS & no bias adjustment and the same aggressive CL RC 6E pads and had absolutely no issues. I could feel the brakes getting just a bit soft on occasion and I was still generating a LOT of heat but they never "failed" like they do at Beaverun.
I purchased an OE GT3 brake line that replaces the restrictor to the rear brakes. May give this a test during the next track day to see if additional rear pressure improves the overall balance. It does seem as if I still have more front bias than would be optimal but I really have no hard data to support this.
Glad to hear that your making headway.
I'm not sure if I understood your configuration correctly, did you have the Tilton valve installed on a 3/16th line with zero bias dialled in or did you have a 3/16th line without a bias valve fitted ?
You previously mentioned some leakage from those 3/16th/M12 flare nuts, did that continue as a problem ?
05-23-2012, 07:29 AM
#74
Pro
I returned the car to the OE line restrictor and OE 1/4" lines. I did not ever run the Tilton due to leakage of the M12 fittings with 3/16 line in them. I'll be back at the local track that tears up my brakes next. Will do some more measurement of specific heat soaking issues there and report back.
05-23-2012, 07:47 AM
#75
Three Wheelin'
Thread Starter
I returned the car to the OE line restrictor and OE 1/4" lines. I did not ever run the Tilton due to leakage of the M12 fittings with 3/16 line in them. I'll be back at the local track that tears up my brakes next. Will do some more measurement of specific heat soaking issues there and report back.
Since my original post I've only run one more track day but it was in the damp/drizzle so it was an excellent opportunity to see what effect the larger rear calipers would have on my car. The car had the standard 5/55 bias valve and a less aggressive rear pad. Whereas I was expecting the tail to get loose under brakes in these conditions, it didn't turn out that way at all. I didnt record rotor temperatures but the rotor condition & dust is indicating that the fronts have still been doing the bulk of the work.
Next week I'm back at the track and conditions should be dry so I intend to run with the standard bias valve and pads with similar performance front & rear (PFC 08 & PFC 06). I will be busy on that day as I have a full day of coaching shared with a mate but I am hoping to record some front vs rear rotor temps and if I'm really organised I might do a rear pad change (to EBC Yellow as used in the wet) and see how the rotor temps compare with that combination.