model 80 - master upgrade
- Thread starter lonnie
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Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Quite a few choices in the wilwood product line lonnie.
I'm working on spec'ing a wilwood now with a remote reservoir for this rig:
http://www.forums.IHPartsAmerica.com/readers-rides/2550-ol-yellar.html
Are you intending to keep the oem brake set for this particular s80? If so, "which" brake set is currently installed? That matters due to the front and rear wheel cylinder diameters you have now or plan to use...the master cylinder needs to "match" the wheel cylinders.
mastercylinder
The "option" brakes on the s80 were a 10" lockheed set on the front, and an 11" by 1-3/4" bendix set on the rear. Tell me which brake sets ya have, I'll give ya the wheel cylinder diameters for each.
I also assume ya wanna go to a dual/split master and wheel setup?? That's really no big deal and is actually easier than dealing with the crapball oem stuff. If you choose the correct bore size wilwood, the setup should balance out ok...if it needs fine tuning, then install a manual-adjust proportioning valve in the rear circuit only and then just dial it in and lock it down! You will also need to incorporate a pair of "residual pressure valves" in the plumbing...10psi for the wilwood mc with the oem wheel cylinders.
This pic is a lockheed 10" front for the s80/d27 axle set (the "option" brakes).
I'm working on spec'ing a wilwood now with a remote reservoir for this rig:
http://www.forums.IHPartsAmerica.com/readers-rides/2550-ol-yellar.html
Are you intending to keep the oem brake set for this particular s80? If so, "which" brake set is currently installed? That matters due to the front and rear wheel cylinder diameters you have now or plan to use...the master cylinder needs to "match" the wheel cylinders.
mastercylinder
The "option" brakes on the s80 were a 10" lockheed set on the front, and an 11" by 1-3/4" bendix set on the rear. Tell me which brake sets ya have, I'll give ya the wheel cylinder diameters for each.
I also assume ya wanna go to a dual/split master and wheel setup?? That's really no big deal and is actually easier than dealing with the crapball oem stuff. If you choose the correct bore size wilwood, the setup should balance out ok...if it needs fine tuning, then install a manual-adjust proportioning valve in the rear circuit only and then just dial it in and lock it down! You will also need to incorporate a pair of "residual pressure valves" in the plumbing...10psi for the wilwood mc with the oem wheel cylinders.
This pic is a lockheed 10" front for the s80/d27 axle set (the "option" brakes).
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Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Thanks michael - as usual, you are so well read up on Scout issues reading your response is like opening up the factory manual and turing to the right page immediately.
While I have no interest on keeping the oem set up, I would like to keep the upgrade relatively simple. My braking demands are modest so I am hopeful there are some options.
As regards wheel cylinders, I am not certain which size I have. I did change out both axles with the front being a Dana 30 and the rear, a 44. From this I would guess this translates to 10 (front) and 11 3/4 (rear).
Yes it would be great to go to a split master. As for the residual pressure valves, I do not have much experience with them and so ask you if they are a nice to have item or must have even with a basic set like ours.
Given the above do you have a specific wilwood recommendation?
Again many thanks for all your help.
While I have no interest on keeping the oem set up, I would like to keep the upgrade relatively simple. My braking demands are modest so I am hopeful there are some options.
As regards wheel cylinders, I am not certain which size I have. I did change out both axles with the front being a Dana 30 and the rear, a 44. From this I would guess this translates to 10 (front) and 11 3/4 (rear).
Yes it would be great to go to a split master. As for the residual pressure valves, I do not have much experience with them and so ask you if they are a nice to have item or must have even with a basic set like ours.
Given the above do you have a specific wilwood recommendation?
Again many thanks for all your help.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Ok lonnie, let's assume that the d30 ya installed has the typical drum brake version (is it an "open knuckle" from a Scout II donor??). If so, those are gonna be 11" bendix-pattern brakes...very common items. Same for the rear if the axle donor was Scout II.
There was one wheel cylinder diameters used on the sii/d30 front...and two different ones on the rear!
So, for this purpose we're gonna figgr on a drum/drum combo, just basic Scout II type bendix stoppers.
The fronts should be 1-1/8". The rears could be either 13/16" or 15/16". No matter...a 1" master cylinder bore size is whatcha wanna look at.
The residual pressure valves are normally built into a dual circuit master cylinder and are inside the outlet ports. Replacement master hardly ever have a residual valve set installed which is a problem! You do need those items on any brake system. In the case of drums, the residual valve provides a nominal 5>10psi. That keeps the shoes expanded real close to the drums so that when ya press the pedal, there is minimal distance the wheel cylinders have to provide travel for. Not so close as to create excessive drag/heat, but just close enough so that ya have a hard/firm pedal with minimal travel. And non-power brakes or boosted brakes, this does not matter, they both need rpv in each end.
As for "which" wilwood mc, that is a budget item! If I'm spending your dinero, then it's only the high end stuff for me! Look at the drawing dimensions for the mounting flanges and compare with an oem s80 mc. If ya don't have an oem item on the shelf, I do and and can give ya the dimensions. You will most likely need to fab a pushrod, incorporating your oem pushrod since it already mates to the pedal correctly.
Look at the wilwood tandem p/n 260-8555. If you want to go single circuit only, there are several less expensive options in a 1" master. You will also need to add a tee fitting most likely to be able to use your hydraulic brake light switch unless ya convert to a mechanical switch actuated from the pedal set.
There was one wheel cylinder diameters used on the sii/d30 front...and two different ones on the rear!
So, for this purpose we're gonna figgr on a drum/drum combo, just basic Scout II type bendix stoppers.
The fronts should be 1-1/8". The rears could be either 13/16" or 15/16". No matter...a 1" master cylinder bore size is whatcha wanna look at.
The residual pressure valves are normally built into a dual circuit master cylinder and are inside the outlet ports. Replacement master hardly ever have a residual valve set installed which is a problem! You do need those items on any brake system. In the case of drums, the residual valve provides a nominal 5>10psi. That keeps the shoes expanded real close to the drums so that when ya press the pedal, there is minimal distance the wheel cylinders have to provide travel for. Not so close as to create excessive drag/heat, but just close enough so that ya have a hard/firm pedal with minimal travel. And non-power brakes or boosted brakes, this does not matter, they both need rpv in each end.
As for "which" wilwood mc, that is a budget item! If I'm spending your dinero, then it's only the high end stuff for me! Look at the drawing dimensions for the mounting flanges and compare with an oem s80 mc. If ya don't have an oem item on the shelf, I do and and can give ya the dimensions. You will most likely need to fab a pushrod, incorporating your oem pushrod since it already mates to the pedal correctly.
Look at the wilwood tandem p/n 260-8555. If you want to go single circuit only, there are several less expensive options in a 1" master. You will also need to add a tee fitting most likely to be able to use your hydraulic brake light switch unless ya convert to a mechanical switch actuated from the pedal set.
Michael-again, thanks for your most complete response.
I do want to add a couple of comments to this which May or May not change what you had to say.
1. The replacement axles are from a 800;
2. Yes mine is a drum/drum combo;
3. Yes, I am fine with buying higher quality (as long as it works);
4. No, I did not convert the brake light switch;
thanks for the summit reference, I will certainly follow up on that.
As a note to all and based on your comments here, there is no bolt on upgrade (not simple replacement) to the brake master given the axles I am using (regardless of cost).
I do want to add a couple of comments to this which May or May not change what you had to say.
1. The replacement axles are from a 800;
2. Yes mine is a drum/drum combo;
3. Yes, I am fine with buying higher quality (as long as it works);
4. No, I did not convert the brake light switch;
thanks for the summit reference, I will certainly follow up on that.
As a note to all and based on your comments here, there is no bolt on upgrade (not simple replacement) to the brake master given the axles I am using (regardless of cost).
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Thanks for the clarification lonnie, I simply can't keep up with all the various combos/projects ya got in the mill!
The 1" replacement master cylinder recommendation holds though. No matter how ya achieve it!
With much research, you could definitely source a new (no remans please!!!!) oem master for some app that might cost less than the wilwood. The main thing to look for is the mounting pattern for the flange, and the "exit" point for the fittings...left or right. Either side exit can certainly be made to work just fine with the right combo of brake-grade hardware/transition fittings. Same for tapping in the hydraulic pressure switch for the brake lights. Or...the switch could be tapped into the plumbing junction elsewhere in the loop, it does not have to go right there at the mc like on the oem part.
If you wanted to forgo the dual circuit setup, wilwood has some very nice single circuit masters that will be as close to bolt-on as possible. Because of the amount of work I've already put into the brake system on our s80, that is what I'd use if for some reason a replacement mc was needed and I could not come up with oem. But I have excellent luck in rebuilding the oem masters as long as they are not rotted inside (the piston)...an oem cylinder with a rotten bore can be re-sleeved but that is significant dinero...but for some folks/some restos, that is the only option! I've had a couple of masters done by white post restorations but I'd never pay that price again unless a customer insists!
At one point I attempted to locate an oem replacement mc for the s80...new. I had no luck, but they were used in some Jeep apps (mounted under floor iirc). For folks doing "correct" restos, that is important. I'd never use a "nos" master that has set onna shelf for 20+ years without tearing it down and rebuilding!
This pic shows a "stepbore" dual circuit mc for a Scout 800, very difficult item to source new, but at one point both iho and ihon had 'em. This a rebuild I did some time back using some kits I found stashed away at an oldtime parts warehouse. This would be a direct bolt-on for your s80 if ya made the appropriate plumbing pigtails to go either over or through that inner fender panel/support.
This is meant to just be representative of a type of oem mc workaround.
The 1" replacement master cylinder recommendation holds though. No matter how ya achieve it!
With much research, you could definitely source a new (no remans please!!!!) oem master for some app that might cost less than the wilwood. The main thing to look for is the mounting pattern for the flange, and the "exit" point for the fittings...left or right. Either side exit can certainly be made to work just fine with the right combo of brake-grade hardware/transition fittings. Same for tapping in the hydraulic pressure switch for the brake lights. Or...the switch could be tapped into the plumbing junction elsewhere in the loop, it does not have to go right there at the mc like on the oem part.
If you wanted to forgo the dual circuit setup, wilwood has some very nice single circuit masters that will be as close to bolt-on as possible. Because of the amount of work I've already put into the brake system on our s80, that is what I'd use if for some reason a replacement mc was needed and I could not come up with oem. But I have excellent luck in rebuilding the oem masters as long as they are not rotted inside (the piston)...an oem cylinder with a rotten bore can be re-sleeved but that is significant dinero...but for some folks/some restos, that is the only option! I've had a couple of masters done by white post restorations but I'd never pay that price again unless a customer insists!
At one point I attempted to locate an oem replacement mc for the s80...new. I had no luck, but they were used in some Jeep apps (mounted under floor iirc). For folks doing "correct" restos, that is important. I'd never use a "nos" master that has set onna shelf for 20+ years without tearing it down and rebuilding!
This pic shows a "stepbore" dual circuit mc for a Scout 800, very difficult item to source new, but at one point both iho and ihon had 'em. This a rebuild I did some time back using some kits I found stashed away at an oldtime parts warehouse. This would be a direct bolt-on for your s80 if ya made the appropriate plumbing pigtails to go either over or through that inner fender panel/support.
This is meant to just be representative of a type of oem mc workaround.
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Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
This is a pic of the same s800 rebuilt mc which shows the oem residual pressure valve system in each circuit, located behind the transition fitting for each circuit.
The "passenger side exit" of the ports on that s800 mc are kinda unusual, the typical dual circuit mc will have the ports on the driver side of the casting like your Scout II.
The oem Scout 80 mc is very similar in appearance to what was used on single channel Ford apps in the 50's/60's (car and truck), but when I actually compared a new Ford app to the s80, I determined it would be more trouble than it was worth to adapt it.
If...you actually have the s800 stepbore master from the donor for your axles, I have one rebuild kit left on hand...I'd be more than happy to determine if your mc is usable and if so, then rebuild it for ya, just bring it to the club meeting in salem on jan 7! Because they are a step-bore design, the rebuilding process is a bit trickee!!
oops!! I lied lonnie! I do not have a new s800 mc kit on hand afterall, but I can get more so the offer stands!!
The "passenger side exit" of the ports on that s800 mc are kinda unusual, the typical dual circuit mc will have the ports on the driver side of the casting like your Scout II.
The oem Scout 80 mc is very similar in appearance to what was used on single channel Ford apps in the 50's/60's (car and truck), but when I actually compared a new Ford app to the s80, I determined it would be more trouble than it was worth to adapt it.
If...you actually have the s800 stepbore master from the donor for your axles, I have one rebuild kit left on hand...I'd be more than happy to determine if your mc is usable and if so, then rebuild it for ya, just bring it to the club meeting in salem on jan 7! Because they are a step-bore design, the rebuilding process is a bit trickee!!
oops!! I lied lonnie! I do not have a new s800 mc kit on hand afterall, but I can get more so the offer stands!!
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