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Re: Front brake adjustment on modified front brake

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  • pco98
    Hi Tim Many thanks for this article, much appreciated, especially as it is a common topic. I wonder if you can post it in the files section and direct people
    Message 1 of 18 , Jun 1, 2011
      Hi Tim

      Many thanks for this article, much appreciated, especially as it is a common topic.

      I wonder if you can post it in the files section and direct people to it in the future.

      I have the original configuration parts so can go back to that set up. Will sit down with your notes and have a go.

      Ross

      --- In royalenfield@yahoogroups.com, "timbusby" <royalenfield@...> wrote:
      >
      > If you search through the old messages you will find that this topic has been discussed several times...
      > The method of adjustment that you refer to is SERIOUSLY flawed. It was written by some well meaning person, but unfortunately with a complete lack of understanding on how the mechanical Twin Leading shoe brake works.
      > :-(
      > DONT DO IT!
      >
      > For the mechanically operated twin leading shoe drum brake to function at 100% efficiency it is of paramount importance that the linkages operates as a perfect geometric parallelogram: The distance between the centers of the two trunions MUST be the exact same distance as that of the two brake cams.
      > Anything less than a perfectly `square' linkage arrangement will result in the drastically reduced operational efficiency of either one of the paired brake shoes!
      > In which event the Brake is frequently less effective than a single leading shoe brake.
      >
      > With the Brake plate assembly removed from the front wheel, the initial need is to commence by adjusting the external link rod that connects the two brake arms, so that the distance between centers of the trunions is a nominal 143.5mm. Allowance must also be taken into account for `slop' between the trunions and the brake arms, which in turn will frequently see one cam commencing to operate before the other even though the theoretically correct distance between the centers has been set correctly…
      > Then turn the brake plate over and closely inspect how the brake shoes sit against the actuating cams. Hopefully both shoes will be sitting square and flat on both of the brake cams…
      > Due to manufacturing tolerances of the location of the splines which are machined onto the external ends of the two brake cams, and the corresponding splines on the two brake actuating arms this is at times this is not always readily achievable.
      > (When undertaking any refitting of the brake arms onto the spline one must bear in mind that the optimal position of the main actuating arm (the one that the cable pulls on) is such that the angle between the cable and main brake arm is APPROACHING 90 degrees).
      > In which event it may be necessary to remove and reposition one or the other of the brake arms from off its spline, and reposition the arm another notch around on the spline so that both shoes are sitting flush against their respective cams.
      > On occasion even this fine adjustment proves to be inadequate, in which event there are four further options.
      > 1. Careful filing down of the heel of which ever brake shoe that is LEADING .
      > 2. Shimming-up of the brake shoe which is TRAILING.
      > 3. Careful filing down of the cam face of the LEADING shoe.
      > 4. Minor readjustment of the link-rod to SHORTEN the distance between centers of the trunions. (This being the easiest to achieve but it is also the least desirable).
      > Consideration must also be taken into account of manufacturing tolerances between the trunions and their respective brake arms. Trunion diameters vary enough that it contributes additional `lost movement' in the linkages, affecting the `true' length of the top side of the parallelogram. Allowance for any such `slop' by setting the link rod `short' frequently compensates for any such manufacturing tolerances.
      >
      > Refit the brake plate assembly to the wheel, apply the brake and carefully observe the clearance between axle and the central hole in the brake plate. IF the brake plate is not true and central to the axle, one brake shoe will be making premature contact onto the brake drum and (for every action there is a reaction) the brake plate will move in the OPPOSITE direction and make contact with the axle…
      > It is possible that the central hole in the brake plate is not located perfectly central, or that one or the other of the brake shoes is of reduced section (thickness). The latter is most common due to any prior incorrect adjustment of the brake link rod…
      >
      > What ever the reason, one shoe will NOT be making full contact with the brake drum.
      > Remedial options in order of preference:
      > 1 Careful shimming up of the brake shoe on the side of the brake plate that now exhibits the gap between brake plate and axle
      > 2 Careful thinning down of the lining of the shoe with the thicker brake lining.
      > 3 A slight opening up of the central hole in the brake plate to accommodate the true centralization of the brake plate around the axle.
      >
      > With the correctly assembled and adjusted brake plate refitted into the drum, and the brake applied, (centralizing the brake plate to the drum and axle) apply a drop or two of loctite to the Brake plate retaining nut (taper faced), HAND tighten. Do NOT over tighten this nut!
      > When refitting the assembled front wheel into the front forks, ensure that the brake plate retaining nut is positioned HARD up against the side of the fork leg.
      > Such will prevent the nut from ever working loose in service.
      >
      > Final adjustment to ensure maximum brake efficiency is to adjust out ALL free play in the front brake cable, so that the brake shoes are just clear of the drum: Spinning of the wheel should be free and with out any scraping noise resulting from lining and drum making contact.
      > Excessive free play in the front brake cable seriously detracts from operational efficiency of the brake. (The leverage-pivot-cable nipple relationship in the OEM front brake hand lever could be of a better configuration to optimize mechanical advantage)
      >
      > As a `check' on optimal brake shoe contact, strike a series of diagonal chalk lines across the face of both brake shoes prior to reassembly of the wheel and brake.
      > Take a 5km ride applying the brakes regularly down to a complete stop.
      > Remove the wheel, brake plate and inspect the brake linings for signs of the chalk lines…
      > If all has gone according to plan there will be no residual chalk marks…
      > For normal road use a Minimum acceptable contact area is 80%. (Only 20% or less of the chalk lines remain)
      >
      > Tim
      > N.Z.
      >
      >
      > --- In royalenfield@yahoogroups.com, "pco98" <pco98@> wrote:
      > >
      > > Hi all
      > >
      > > Must confess I have a fear of front brake adjustment and would like a bit of guidance before I have a go myself.
      > >
      > > I have done the fairly common mod of reversing the rod so that LH thread and trunnion is at the bottom with the top trunnion drilled out.
      >
    • k3eax
      Well it seems as though we have to different suggestions on how to adjust the front brake. David Murray suggests the common sense, pragmatic, and easily
      Message 2 of 18 , Jun 1, 2011
        Well it seems as though we have to different suggestions on how to adjust the front brake. David Murray suggests the common sense, pragmatic, and easily performed while Tim Busby prefers the exactitude of a theoretically inclined design-engineer . I'd like to hear from others tell of which approach they use and their satisfaction with its results

        Al in Philadelphia
      • pco98
        I did wonder if the modified rod is an easy option, which helps take up the slack one s own and the Bullet s unscientific exactness/fuzziness. Looking fwd to
        Message 3 of 18 , Jun 1, 2011
          I did wonder if the modified rod is an easy option, which helps take up the slack one's own and the Bullet's unscientific exactness/fuzziness.

          Looking fwd to further gentlemanly and/or lady-like debate.

          Ross

          I'd like to hear from others tell of which approach they use and their satisfaction with its results
          >
          > Al in Philadelphia
          >
        • Al
          I ve used David s approach and am very satisfied with the results. His is the same basic approach,  recommended by the manufacturer, that I and other auto
          Message 4 of 18 , Jun 1, 2011
            I've used David's approach and am very satisfied with the results. His is the same basic approach,  recommended by the manufacturer, that I and other auto mechanics  used to adjust the twin leading shoe Lockheed design used by Chrysler Corp. decades ago. 

            While Tim's approach certainly makes good sense when used to adjust new shoes, I have my reservations about its applicability to adjust shoes that have been in service given the fact that would exhibit uneven wear.

                Al in Philadelphia 

            From: pco98 <pco98@...>
            To: royalenfield@yahoogroups.com
            Sent: Wednesday, June 1, 2011 7:35 AM
            Subject: [Enfield] Re: Front brake adjustment on modified front brake

             
            I did wonder if the modified rod is an easy option, which helps take up the slack one's own and the Bullet's unscientific exactness/fuzziness.

            Looking fwd to further gentlemanly and/or lady-like debate.

            Ross

            I'd like to hear from others tell of which approach they use and their satisfaction with its results
            >
            > Al in Philadelphia
            >



          • Dave Murray
            Lordy, Tim. We re not talking about designing the perfect brake setup, optimising it, perfecting the geometry, or otherwise spending a week doing a 5 minute
            Message 5 of 18 , Jun 1, 2011
              Lordy, Tim.
              We're not talking about designing the perfect brake setup, optimising it, perfecting the geometry, or otherwise spending a week doing a 5 minute job.
              We're talking about adjusting the bloody thing. Obviously, that asumes that it is reasonably correctly assembled beforehand.
              This is simply about getting the two shoes to contact the drum as close to simultaneously as possible. With this method, you hear and feel that happen. I make no pretence at your engineering skills, but I have been using this method for over 40 years, and my 2LS setups work. I'm pretty picky about brakes, perfect is good enough. Hanuman was, and Gina is.
              Best,
              DWM

              --- In royalenfield@yahoogroups.com, "timbusby" <royalenfield@...> wrote:
              >
              > If you search through the old messages you will find that this topic has been discussed several times...
              > The method of adjustment that you refer to is SERIOUSLY flawed. It was written by some well meaning person, but unfortunately with a complete lack of understanding on how the mechanical Twin Leading shoe brake works.
              > :-(
              > DONT DO IT!
              >
              > For the mechanically operated twin leading shoe drum brake to function at 100% efficiency it is of paramount importance that the linkages operates as a perfect geometric parallelogram: The distance between the centers of the two trunions MUST be the exact same distance as that of the two brake cams.
              > Anything less than a perfectly `square' linkage arrangement will result in the drastically reduced operational efficiency of either one of the paired brake shoes!
              > In which event the Brake is frequently less effective than a single leading shoe brake.
              >
              > With the Brake plate assembly removed from the front wheel, the initial need is to commence by adjusting the external link rod that connects the two brake arms, so that the distance between centers of the trunions is a nominal 143.5mm. Allowance must also be taken into account for `slop' between the trunions and the brake arms, which in turn will frequently see one cam commencing to operate before the other even though the theoretically correct distance between the centers has been set correctly…
              > Then turn the brake plate over and closely inspect how the brake shoes sit against the actuating cams. Hopefully both shoes will be sitting square and flat on both of the brake cams…
              > Due to manufacturing tolerances of the location of the splines which are machined onto the external ends of the two brake cams, and the corresponding splines on the two brake actuating arms this is at times this is not always readily achievable.
              > (When undertaking any refitting of the brake arms onto the spline one must bear in mind that the optimal position of the main actuating arm (the one that the cable pulls on) is such that the angle between the cable and main brake arm is APPROACHING 90 degrees).
              > In which event it may be necessary to remove and reposition one or the other of the brake arms from off its spline, and reposition the arm another notch around on the spline so that both shoes are sitting flush against their respective cams.
              > On occasion even this fine adjustment proves to be inadequate, in which event there are four further options.
              > 1. Careful filing down of the heel of which ever brake shoe that is LEADING .
              > 2. Shimming-up of the brake shoe which is TRAILING.
              > 3. Careful filing down of the cam face of the LEADING shoe.
              > 4. Minor readjustment of the link-rod to SHORTEN the distance between centers of the trunions. (This being the easiest to achieve but it is also the least desirable).
              > Consideration must also be taken into account of manufacturing tolerances between the trunions and their respective brake arms. Trunion diameters vary enough that it contributes additional `lost movement' in the linkages, affecting the `true' length of the top side of the parallelogram. Allowance for any such `slop' by setting the link rod `short' frequently compensates for any such manufacturing tolerances.
              >
              > Refit the brake plate assembly to the wheel, apply the brake and carefully observe the clearance between axle and the central hole in the brake plate. IF the brake plate is not true and central to the axle, one brake shoe will be making premature contact onto the brake drum and (for every action there is a reaction) the brake plate will move in the OPPOSITE direction and make contact with the axle…
              > It is possible that the central hole in the brake plate is not located perfectly central, or that one or the other of the brake shoes is of reduced section (thickness). The latter is most common due to any prior incorrect adjustment of the brake link rod…
              >
              > What ever the reason, one shoe will NOT be making full contact with the brake drum.
              > Remedial options in order of preference:
              > 1 Careful shimming up of the brake shoe on the side of the brake plate that now exhibits the gap between brake plate and axle
              > 2 Careful thinning down of the lining of the shoe with the thicker brake lining.
              > 3 A slight opening up of the central hole in the brake plate to accommodate the true centralization of the brake plate around the axle.
              >
              > With the correctly assembled and adjusted brake plate refitted into the drum, and the brake applied, (centralizing the brake plate to the drum and axle) apply a drop or two of loctite to the Brake plate retaining nut (taper faced), HAND tighten. Do NOT over tighten this nut!
              > When refitting the assembled front wheel into the front forks, ensure that the brake plate retaining nut is positioned HARD up against the side of the fork leg.
              > Such will prevent the nut from ever working loose in service.
              >
              > Final adjustment to ensure maximum brake efficiency is to adjust out ALL free play in the front brake cable, so that the brake shoes are just clear of the drum: Spinning of the wheel should be free and with out any scraping noise resulting from lining and drum making contact.
              > Excessive free play in the front brake cable seriously detracts from operational efficiency of the brake. (The leverage-pivot-cable nipple relationship in the OEM front brake hand lever could be of a better configuration to optimize mechanical advantage)
              >
              > As a `check' on optimal brake shoe contact, strike a series of diagonal chalk lines across the face of both brake shoes prior to reassembly of the wheel and brake.
              > Take a 5km ride applying the brakes regularly down to a complete stop.
              > Remove the wheel, brake plate and inspect the brake linings for signs of the chalk lines…
              > If all has gone according to plan there will be no residual chalk marks…
              > For normal road use a Minimum acceptable contact area is 80%. (Only 20% or less of the chalk lines remain)
              >
              > Tim
              > N.Z.
              >
              >
              > --- In royalenfield@yahoogroups.com, "pco98" <pco98@> wrote:
              > >
              > > Hi all
              > >
              > > Must confess I have a fear of front brake adjustment and would like a bit of guidance before I have a go myself.
              > >
              > > I have done the fairly common mod of reversing the rod so that LH thread and trunnion is at the bottom with the top trunnion drilled out.
              >
            • Dave Murray
              David Murray suggests the common sense, pragmatic, and easily performed while Tim Busby prefers the exactitude of a theoretically inclined design-engineer .
              Message 6 of 18 , Jun 1, 2011
                "David Murray suggests the common sense, pragmatic, and easily
                performed while Tim Busby prefers the exactitude of a theoretically inclined
                design-engineer ."
                Any mechanic is constantly trying to achieve a balance between those two views. In reality, we aspire to the latter, and to some extent, settle for the former. One can allow the "perfect" to become the enemy of the "good." A new mechanic might be so intimidated by the standards of perfection that he doesn't do the operation at all, although a "good" result is well within his capabilities. I'd rather see the brake adjusted as well as possible than not at all between dealer visits. Even then, the professional mechanic has to limit his pursuit of perfection due to financial reality. No owner is going to pay 10 hours labor for a brake adjustment. For a rebuild, maybe, but not an adjustment.
                Best,
                DWM

                --- In royalenfield@yahoogroups.com, "k3eax" <k3eax@...> wrote:
                >
                >
                >
                > Well it seems as though we have to different suggestions on how to adjust the front brake. David Murray suggests the common sense, pragmatic, and easily performed while Tim Busby prefers the exactitude of a theoretically inclined design-engineer . I'd like to hear from others tell of which approach they use and their satisfaction with its results
                >
                > Al in Philadelphia
                >
              • timbusby
                This is a RE we are talking about... I have yet to see one straight out of the crate with its front brake correctly assembled. Tim N.Z.
                Message 7 of 18 , Jun 3, 2011
                  This is a RE we are talking about...
                  I have yet to see one straight out of the crate with its front brake correctly assembled.

                  Tim
                  N.Z.

                  --- In royalenfield@yahoogroups.com, "Dave Murray" <redhawk34@...> wrote:
                  >

                  > We're talking about adjusting the bloody thing. Obviously, that asumes that it is reasonably correctly assembled beforehand.
                • timbusby
                  If one want to settle for second best, then that is up to the individual: Near enough is good enough for some people. Timing? Holed pistons are easy to
                  Message 8 of 18 , Jun 3, 2011
                    If one want to settle for second best, then that is up to the individual: Near enough is good enough for some people.
                    Timing? Holed pistons are easy to replace.
                    Loose Tappets? You only loose power and hammer the tops of the valves.
                    Main jet? Pistons normally free up after they have seized...

                    And Al; the offer of a free trip to NZ is still open when ever you want to compare/test your preferred method of brake adjustment...
                    If your preferred method of brake adjustment is the better; the trip is on me.

                    Tim
                    N.Z.


                    --- In royalenfield@yahoogroups.com, "k3eax" <k3eax@...> wrote:
                    >
                    >
                    >
                    > Well it seems as though we have to different suggestions on how to adjust the front brake. David Murray suggests the common sense, pragmatic, and easily performed while Tim Busby prefers the exactitude of a theoretically inclined design-engineer . I'd like to hear from others tell of which approach they use and their satisfaction with its results
                    >
                    > Al in Philadelphia
                    >
                  • timbusby
                    Lockheed and Chrysler both gave up on mechanical brakes in the 30/40 s and to the best of my knowledge neither of them used a mechanical Twin leader. All went
                    Message 9 of 18 , Jun 3, 2011
                      Lockheed and Chrysler both gave up on mechanical brakes in the 30/40's and to the best of my knowledge neither of them used a mechanical Twin leader.
                      All went to Hydraulic for twin leading shoe drum brakes and had micam individual shoe adjusters.
                      The similarity between mechanical and hydraulic brakes is akin to comparing a Side valve engine to a Double overhead cam.

                      Tim
                      N.Z.

                      --- In royalenfield@yahoogroups.com, Al <k3eax@...> wrote:
                      >
                      > I've used David's approach and am very satisfied with the results. His is the same basic approach,  recommended by the manufacturer, that I and other auto mechanics  used to adjust the twin leading shoe Lockheed design used by Chrysler Corp. decades ago. 
                      >
                      > While Tim's approach certainly makes good sense when used to adjust new shoes, I have my reservations about its applicability to adjust shoes that have been in service given the fact that would exhibit uneven wear.
                      >
                      >     Al in Philadelphia 
                    • Al
                      Tim, the Lockheed twin leading shoe design as used by Chrysler to which I referred  was an hydraulic system. My harkening back to it was an effort to show
                      Message 10 of 18 , Jun 4, 2011
                        Tim, the Lockheed twin leading shoe design as used by Chrysler to which I referred  was an hydraulic system. My harkening back to it was an effort to show the similarity in the approach to adjustment that exists to the method  used by most RE owners such as David.

                        All that said, and now to put it in a few word, I don't believe that your meticulous adjustment method is worth the effort on brake shoes that have been in service and consequently worn unevenly.

                          Al in Philadelphia


                        From: timbusby <royalenfield@...>
                        To: royalenfield@yahoogroups.com
                        Sent: Saturday, June 4, 2011 1:07 AM
                        Subject: [Enfield] Re: Front brake adjustment on modified front brake

                         
                        Lockheed and Chrysler both gave up on mechanical brakes in the 30/40's and to the best of my knowledge neither of them used a mechanical Twin leader.
                        All went to Hydraulic for twin leading shoe drum brakes and had micam individual shoe adjusters.
                        The similarity between mechanical and hydraulic brakes is akin to comparing a Side valve engine to a Double overhead cam.

                        Tim
                        N.Z.

                        --- In royalenfield@yahoogroups.com, Al <k3eax@...> wrote:
                        >
                        > I've used David's approach and am very satisfied with the results. His is the same basic approach,  recommended by the manufacturer, that I and other auto mechanics  used to adjust the twin leading shoe Lockheed design used by Chrysler Corp. decades ago. 
                        >
                        > While Tim's approach certainly makes good sense when used to adjust new shoes, I have my reservations about its applicability to adjust shoes that have been in service given the fact that would exhibit uneven wear.
                        >
                        >     Al in Philadelphia 



                      • Dave Murray
                        Tim, As I understand it, 2LS brakes were not used on street cars simply because they don t work worth a damn in reverse. Not an issue on a bike. Some race cars
                        Message 11 of 18 , Jun 4, 2011
                          Tim,
                          As I understand it, 2LS brakes were not used on street cars simply because they don't work worth a damn in reverse. Not an issue on a bike. Some race cars may have used them.
                          Best,
                          DWM

                          --- In royalenfield@yahoogroups.com, "timbusby" <royalenfield@...> wrote:
                          >
                          > Lockheed and Chrysler both gave up on mechanical brakes in the 30/40's and to the best of my knowledge neither of them used a mechanical Twin leader.
                          > All went to Hydraulic for twin leading shoe drum brakes and had micam individual shoe adjusters.
                          > The similarity between mechanical and hydraulic brakes is akin to comparing a Side valve engine to a Double overhead cam.
                          >
                          > Tim
                          > N.Z.
                          >
                          > --- In royalenfield@yahoogroups.com, Al <k3eax@> wrote:
                          > >
                          > > I've used David's approach and am very satisfied with the results. His is the same basic approach,  recommended by the manufacturer, that I and other auto mechanics  used to adjust the twin leading shoe Lockheed design used by Chrysler Corp. decades ago. 
                          > >
                          > > While Tim's approach certainly makes good sense when used to adjust new shoes, I have my reservations about its applicability to adjust shoes that have been in service given the fact that would exhibit uneven wear.
                          > >
                          > >     Al in Philadelphia 
                          >
                        • Al
                          The Lockheed 2ls hydraulic system was used by Chrysler for many years  --- and as I recall, right up to the early 60 s. Their use while going in reverse was
                          Message 12 of 18 , Jun 4, 2011
                            The Lockheed 2ls hydraulic system was used by Chrysler for many years  --- and as I recall, right up to the early '60's. Their use while going in reverse was never an issue to my knowledge.

                            The 2ls Lockheed was replaced by a Bendix design which was easier to adapt to an inexpensive and reliable self-adjusting set-up --- something that Lockheed never could manage to provide..

                            The 2ls approach has the advantage of having two primary shoes which enjoy the benefit of a "self-servo" boost when braking. This brought about by the leading shoe -- in this case two leading shoes -- being forced against the  drum with  additional pressure provided by its rotation --- sometimes called "wrap-up pressure". The boost in braking power that results from the self-servo effect is absent in reverse as the shoes do do not wrap-up against the drum  . This is brought home to the Enfield owner when applying the brake while rolling down an incline 

                              Al in Philadelphia 



                            From: Dave Murray <redhawk34@...>
                            To: royalenfield@yahoogroups.com
                            Sent: Saturday, June 4, 2011 9:50 AM
                            Subject: [Enfield] Re: Front brake adjustment on modified front brake

                             
                            Tim,
                            As I understand it, 2LS brakes were not used on street cars simply because they don't work worth a damn in reverse. Not an issue on a bike. Some race cars may have used them.
                            Best,
                            DWM

                            --- In royalenfield@yahoogroups.com, "timbusby" <royalenfield@...> wrote:
                            >
                            > Lockheed and Chrysler both gave up on mechanical brakes in the 30/40's and to the best of my knowledge neither of them used a mechanical Twin leader.
                            > All went to Hydraulic for twin leading shoe drum brakes and had micam individual shoe adjusters.
                            > The similarity between mechanical and hydraulic brakes is akin to comparing a Side valve engine to a Double overhead cam.
                            >
                            > Tim
                            > N.Z.
                            >
                            > --- In royalenfield@yahoogroups.com, Al <k3eax@> wrote:
                            > >
                            > > I've used David's approach and am very satisfied with the results. His is the same basic approach,  recommended by the manufacturer, that I and other auto mechanics  used to adjust the twin leading shoe Lockheed design used by Chrysler Corp. decades ago. 
                            > >
                            > > While Tim's approach certainly makes good sense when used to adjust new shoes, I have my reservations about its applicability to adjust shoes that have been in service given the fact that would exhibit uneven wear.
                            > >
                            > >     Al in Philadelphia 
                            >



                          • timbusby
                            Mechanical TLS brakes are as much good as Hip pockets on under pants when the wheel rotation is reversed. Cars with power-boost (vacuum) hydraulic brakes can
                            Message 13 of 18 , Jun 4, 2011
                              Mechanical TLS brakes are as much good as Hip pockets on under pants when the wheel rotation is reversed.
                              Cars with power-boost (vacuum) hydraulic brakes can make a TLS work at the sort of speeds that one usually encounters while traveling backwards. And besides, TLS hydraulic brakes were fitted to the front; the rears always were a SLS brake, so you still always had at least 50% braking effect; more than enough at low speed
                              ;-)

                              Tim
                              N.Z.


                              --- In royalenfield@yahoogroups.com, "Dave Murray" <redhawk34@...> wrote:
                              >
                              > Tim,
                              > As I understand it, 2LS brakes were not used on street cars simply because they don't work worth a damn in reverse. Not an issue on a bike. Some race cars may have used them.
                              > Best,
                              > DWM
                              >
                              > --- In royalenfield@yahoogroups.com, "timbusby" <royalenfield@> wrote:
                              > >
                              > > Lockheed and Chrysler both gave up on mechanical brakes in the 30/40's and to the best of my knowledge neither of them used a mechanical Twin leader.
                              > > All went to Hydraulic for twin leading shoe drum brakes and had micam individual shoe adjusters.
                              > > The similarity between mechanical and hydraulic brakes is akin to comparing a Side valve engine to a Double overhead cam.
                              > >
                              > > Tim
                              > > N.Z.
                              > >
                              > > --- In royalenfield@yahoogroups.com, Al <k3eax@> wrote:
                              > > >
                              > > > I've used David's approach and am very satisfied with the results. His is the same basic approach,  recommended by the manufacturer, that I and other auto mechanics  used to adjust the twin leading shoe Lockheed design used by Chrysler Corp. decades ago. 
                              > > >
                              > > > While Tim's approach certainly makes good sense when used to adjust new shoes, I have my reservations about its applicability to adjust shoes that have been in service given the fact that would exhibit uneven wear.
                              > > >
                              > > >     Al in Philadelphia 
                              > >
                              >
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