I believe there are several misnomers in the brake world. The “balancing” valve must just be an adjustable needle valve that would slow the passage of hydraulic fluid to the rear brakes. Rather crude, but effective. As soon as the necessary fluid builds up in the rear wheel cylinders, the pressure would quickly build up and equalize at all four wheels—assuming no ABS. Perhaps the problem is transitory in a panic stop. Normal gradual braking would not be as sensitive to lockup. Certainly, now, ABS systems control timing of brake fluid to each wheel and that is great progress and seems to work reliably. I have engaged ABS several times and was grateful for the assistance in bringing my vehicle to a rapid stop. The last time was pulling a loaded car trailer over a snowy mountainous pass. ABS enabled controlled braking just to slow down on the slick downhill portion and assisted compression 4WD braking and the engagement of Trailer Towing mode on our ’05 hemi-rango. Still, a thrill a minute as a very slow moving truck loomed up in the snowy darkness. The other misnomer is calling the device in the outlet of a master cylinder a “check valve”. It is there in an attempt to hold a little positive pressure on the hydraulic system after the pedal is released and thereby reduce the tendency to suck in moist air at the wheel cylinders. The device must also of necessity be only a flow restrictor as hydraulic fluid must flow from the tubing/wheel cylinder system back into the master cylinder. I can visualize a more sophisticated system that would hold a precise static pressure on the system but can’t believe the device in the MC is much more than a restrictor orifice. BTW, the restrictor must not be present in a master MC driving a remotely-boosted slave MC as it is critical that all residual pressure be bled from the line between the master MC and its slave to avoid shoe and pad drag. There is not enough spring action in the booster to overcome the restrictor and too much pressure will be retained on the braking system. The master MC on our ram-engined ‘64K carries a different Chrysler part number from the unboosted MC on a base MoPar. The only difference is the presence of the “check valve” in the unboosted ram MC. New unboosted MC’s are readily available but must have the restrictor removed which is easy. Disassemble the MC and drive the restrictor out with a punch from the piston end. There being a single steel hydraulic line between the master MC and the boosted slave MC in a ’63-’64 ram car (maybe others) and the boosted MC located under the battery box, conversion to a true dual MC system has been problematic and unresolved to my knowledge. Finally (whew), I have personal and photographic evidence of the addition of a ram-induction system to a non-ram 300K with the standard boosted MC. The hydraulic tubing was routed out of an existing bottom outlet and the horizontal outlet was plugged. This actually all fit but with maybe only ¼” between the ram system and the MC plug. Probably not enough for Chrysler and they saw fit to install the rather expensive remotely-boosted MC in the wheel well. Remotely boosted MC’s were fairly common in trucks at the time as the slave MC’s were larger and difficult to hang on a truck’s firewall. The system works just fine but does rely on the full mechanical integrity of the entire system. Rich Barber Brentwood, CA From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of jkg@xxxxxxxxxxxxxxxxx [Chrysler300]
Sent: Saturday, July 25, 2015 2:05 PM
To: Anna F Noia <sa-noia@xxxxxxxxxxx>
Cc: Knutsen, Mark <Mark.Knutsen@xxxxxxxxxxxxxxxxx>; Chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] 300G Brakes - Dual Master Cylinder Conversion
Does anyone really understand how these aftermarket "balance" front to back valves work ? Without say a floating piston of say two diameters it cannot "change pressure front to back " ..and then keep a ratio as pressure changes. The stepped piston to do that ( could be done) would have to displace as much fluid on each side as a master and be as big as a master . And would not be adjustable in machined in diameter / pressure ratio . I got into the 4 pipe ones mopar put in dodge trucks in late 70's . Although called balance valve , disc brake valve , proportional valve etc what it REALLY does ( surprise coming ) is it has a very small piston that sits in the middle--- if pressures are the same on each side , it never moves hardly at all (ends of piston chambers connect to F and rear ) . If unbalanced F to Rear it moves about 1/4 " and turns on the light , by grounding a feeler that then touches necked down center of piston and at same time I think it closes or restricts the outlet port in line with piston , with the high flow ( gas meters have this , excess flow valve shuts of gas if over normal flow and locks off, held there by gas pressure = broken pipe in both cases ) .makes these Dodges a total bear to bleed . Open one part to bleed , piston moves , light goes on . And to end up with light off is a long game of one then the other .. After air is out .
But it might save your tail if a line bursts . So they mean it checks F-R pressure balance , NOT impacting brake balance at all . I think this function was misunderstood by many right from the get go , due to words used around that valve . And passed on down . "Experts" told me stuff that was 100% wrong on what does (" it is needed for discs "etc ) . It has no function except safety . For sure . I took it apart . You can see what it does. Nothing else in it . If a simple needle valve is used in rear ( ? What is sold by hot rod guys) it cannot change ( the eventual) pressure , but would slow initial application of rear brakes .. But pressure would soon rise to whatever it is . I have talked to a lot of people about this , no one really knows a coherent explanation of what it does , or is intended to do , and how it does it . ( last part is essential knowledge) Yes it works, to ?delay ? Rears , might be all it does . Anyone really know ?? It may be that braking ratio is set forever by wheel cylinder bores ( common sense , equal front and rear MC bores) ---and unadjustable brake parts on say a high performance Vette say that is true ) and if you go too far from stock on that ---it cannot ever work right by adjusting a needle valve in the rear line. In fact can be a disaster where big back brake just locks up a bit later .. Yet people increase rear brakes or mix up parts and think this valve will fix it ... ??? Yes ---agree, if you shut off back brakes with a needle valve restriction , they for sure will not lock up as soon (!) I once saw a wilwood setup with a bar across two single masters , you effectively move pedal push point horizontally along the bar , between the two masters ---used in circle track cars . That will really adjust front to rear ratio . It would seem one should stick with matched parts . I used full setup off late 60 's Dodge cop car on fifties torsion bar dodge . Because of this thinking . Ratio is built into the cop car disc / drum brakes day one . . And correct ? Understanding all this is critical ? 57 61 12" total contact brakes are almost ok when they work right , but seldom do . So doing front discs correctly re : balance is something we need to understand better. Cannot pick a master or disc cuz it fits booster easy . Well , you can , I guess . And maybe we get lucky . First guess says rear wheel cylinders set MC bore, same size as car they came from . Plus the prior long story of pedal ratio and bore sizes ...... .......and residual pressure valves . Comments welcome . Still learning .. Just a reminder, don't forget the proportioning valve that mounts below the Master Cylinder. I would suggest one with an adjustable balance front to rear. This will eliminate the lock up experienced when one set of brakes stops before the other. Usually the rears lock up. With the adjustable valve, you can set it so lock up does not occur during a hard stop. May I also suggest, get the rear disc's also. Mine came from a 74 Imperial 9 1/4" rear end, they bolted straight on to my 8 3/4" rear end. The new emergency brake cables even hooked up with the proper lengths. Remember, any disc brakes are better than none, front and rear are way better than just fronts. Next you should consider a "Rear sway bar" that too will give you a significant increase in handling, that's a whole other discussion.....Good Luck!#! Best Regards,
Stephen A. Noia
1-408-210-4736 cell Dan I read your conversion write up on the web site. It is very good and I like the way the final product looks. The Wagner MC 71258 came from an e-mail Gary Barker put out in 2012. He stated it was bolt on to his 300F. When I look up the specification on that master it shows it is for a car with both disc and drums so I’m hoping that means there will be no residual valve on one of the ports. It also appears to have a bolt down lid like our original masters. I have an e-mail out to Stainless Steel Brakes to see what modifications are needed with their MC. Way back when, I converted my F to disc brakes and subsequently installed a dual MC. I chose an MC from a '69 Barracuda of Dart. It installs nicely and is not to hard to add fluid to. The only mods I needed to make were to remove the residual valve in one port, make the ball on the end of the push rod just a tiny bit smaller in diameter to fit into the push rod of the MC and install a brake switch beneath the dash. I chose to make the ball smaller so that if I ever needed to replace the MC on the road, I would not have to monkey around with enlarging the hole in the MC push rod. My story is in the Technical section of our web site. I have talked to many dirt racers and they all say that if you want more braking power, use a smaller MC. E-mail me if you want to discuss this further. Good luck. ___________________________________________________________________ Stainless Steel Brakes provides a DB master cylinder for their front disc conversions. Piston needs some modification. If I remember John Hertog used a 1962 piston on my car? Clip does not work. Needed to make a special clamp to hold lid on or wire ties. All this for my 1960. Close to 1961? I'd be interested in knowing, as I had always heard/read that there wasn't enough room behind the carb/ram setup for a dual master. Maybe that was correct at the time, but perhaps a solution has been found since then? Hopefully a quick question for the group. I am researching the front disc/dual master cylinder conversion for my G. Is the recommended master cylinder for the disc/drum setup a Wagner MC71258 (previously the F71258)? It appears there are others that will work, but they require modifications either to the height, the lid attachment, or removal of a residual pressure valve. This one seems to be able to bolt right on with only the possible modification to the brake push rod diameter.
|
__._,_.___
Posted by: "Rich Barber" <c300@xxxxxxx>
To send a message to this group, send an email to:
Chrysler300@xxxxxxxxxxxxxxx
To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or
go to https://groups.yahoo.com/neo/groups/all/manage/edit
For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm
For archives go to http://www.forwardlook.net/300-archive/search.htm#querylang
![]()
__,_._,___
|
