S4 brake update in OB
#17
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Since Adam is going to get rained on once in a while
, perhaps cunifer might be a longer-term solution than steel? We're not all blessed with San Diego weather......
http://www.fedhillusa.com/
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http://www.fedhillusa.com/
#18
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So I got my Wilwood proportioning valve in the mail today.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0280_zpsfc5cfd19.jpg)
If all goes as planned, I hope to receive my new clutch master by the end of the week.
I imagine by Sunday I'll be a bubble flarin' fool trying to get all these new hydraulics installed.
I was initially planning on just ordering a stock of brake line, fittings, and making my own. But a quick trip to the local independent parts store shows that they have pre-made brake lines - fliared with fittings - on the wall. Just choose your length and bend to fit. My plan is to use these as much as possible, and just fabricate where I need to. We also have a great local hydraulic hose shop, so I may see what pricing they have for special lengths before I make this a total DIY.
Quick question. The Wilwood bias valve says its good from 1000 psi to 100 psi. I'm presuming that means at full open (actually, with the **** cranked all the way down), the max pressure that the valve will allow to flow is 1000 psi. Does anyone know the line pressure of the S4 brake system? I'm trying to determine what the range of adjustability is going to be once I install this, if it will be truly be 100 to 1000 psi or something less.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0280_zpsfc5cfd19.jpg)
If all goes as planned, I hope to receive my new clutch master by the end of the week.
I imagine by Sunday I'll be a bubble flarin' fool trying to get all these new hydraulics installed.
I was initially planning on just ordering a stock of brake line, fittings, and making my own. But a quick trip to the local independent parts store shows that they have pre-made brake lines - fliared with fittings - on the wall. Just choose your length and bend to fit. My plan is to use these as much as possible, and just fabricate where I need to. We also have a great local hydraulic hose shop, so I may see what pricing they have for special lengths before I make this a total DIY.
Quick question. The Wilwood bias valve says its good from 1000 psi to 100 psi. I'm presuming that means at full open (actually, with the **** cranked all the way down), the max pressure that the valve will allow to flow is 1000 psi. Does anyone know the line pressure of the S4 brake system? I'm trying to determine what the range of adjustability is going to be once I install this, if it will be truly be 100 to 1000 psi or something less.
#20
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If it's an OB you need to change to steel lower ball joints, 993 front rotors (ironically cheaper than S4 fronts), and caliper adapters with S4 caliper bolts, and appropriate brake lines. This applies if you are keeping with OB front suspension. There really is no need to change to S4 suspension especially since some of the parts are not serviceable and it is a pain to install. And yes you do keep the OB front hubs.
#22
Three Wheelin'
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If it's an OB you need to change to steel lower ball joints, 993 front rotors (ironically cheaper than S4 fronts), and caliper adapters with S4 caliper bolts, and appropriate brake lines. This applies if you are keeping with OB front suspension. There really is no need to change to S4 suspension especially since some of the parts are not serviceable and it is a pain to install. And yes you do keep the OB front hubs.
I would still like to know if I can use the OB hubs with my S4 control arms and upright.
#23
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Here's the rough in installation. Took a some practice, but finally got the hang of making bubble flares. Nothing is anchored down yet, but this is pretty much the final install.
Props to anyone who has replaced a booster without removing the engine, seems like it would be impossible.
I retained the stock lines wherever possible. They are much softer than steel, and are no problem to flair on the car. The steel ones I did on the bench in the vice to be able to hold them dead square.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0322_zps5126e533.jpg)
Now I need to turn to the pedal side of things and finish up. Need to install the brake light switch and see what's going on with the linkage, it looks too short to reach the pedal at the moment.
Props to anyone who has replaced a booster without removing the engine, seems like it would be impossible.
I retained the stock lines wherever possible. They are much softer than steel, and are no problem to flair on the car. The steel ones I did on the bench in the vice to be able to hold them dead square.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0322_zps5126e533.jpg)
Now I need to turn to the pedal side of things and finish up. Need to install the brake light switch and see what's going on with the linkage, it looks too short to reach the pedal at the moment.
#24
Nordschleife Master
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Ok, factory is 18 bar so 261 psi
33 bar is 478
I would start at around 500 with your suspension setup and increase from there
To set, wilwood has a pressure gauge which threads into the caliper instead of the bleeder and reads the pressure. So install have a helper push the brakes, then watch the pressure and adjust. The helper has to hold the brakes at max pressure for this to work.
33 bar is 478
I would start at around 500 with your suspension setup and increase from there
To set, wilwood has a pressure gauge which threads into the caliper instead of the bleeder and reads the pressure. So install have a helper push the brakes, then watch the pressure and adjust. The helper has to hold the brakes at max pressure for this to work.
#25
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Here's the final install. Hope it doesn't leak
.
The adjustable bias valve has ten turns of adjustment and max's out at 1000 psi, so I've got it set to 5 turns out which hopefully equates to 500 psi. Guess I'll have to see what the pressure gauge has to say.
Looking forward to having awesome pedal feel that the OB 9" booster and criss cross master cylinder biasing just wasn't delivering with the S4 calipers that I've been running for awhile.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0331_zps70039236.jpg)
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The adjustable bias valve has ten turns of adjustment and max's out at 1000 psi, so I've got it set to 5 turns out which hopefully equates to 500 psi. Guess I'll have to see what the pressure gauge has to say.
Looking forward to having awesome pedal feel that the OB 9" booster and criss cross master cylinder biasing just wasn't delivering with the S4 calipers that I've been running for awhile.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0331_zps70039236.jpg)
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0333_zps6cd3e383.jpg)
#27
Administrator - "Tyson"
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My 79 still has the OB upper and lower arms, spindle and hub with S4 calipers and standard S4 rotors.
The spindle is modified (no brackets), and they fit under 16" phone dials.
#28
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The last piece of this upgrade is wiring the brake light switch. The stock OB master cylinder has two pressure activated switches on it to activate the brake lights. Pictured below is the S4 set up. You can see the plunger switch is mounted on an "L" bracket in the footwell. The OB does not have bracket, so I'll need to fabricate something.
![](http://i710.photobucket.com/albums/ww110/atb928/IMAG0426_zps84bf54f7.jpg)
#29
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How's your pedal feel been Erik running the stock booster? I had very little pedal feel running the S4 calipers with the stock OB hydraulics. I'm really hoping this project gives me what I'm looking for.
#30
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I've only driven it with Pagid Orange pads and SuperBlue fluid.
It would be kind of funny if the booster was already upgraded. I don't remember the builder of my car mentioning that and I still talk to him on a regular basis. I'll have to measure it and see.