1937-1957 Rear Brake- Fit Problem

Forum rules
Please do not start new topics here, but here: New Panhead and Flathead topics
Panhead Register Member
Posts: 865
Joined: Mon Aug 16, 2010 7:18 pm
Bikes: '46 Knuck. '57 Panhead, '59 Panhead
Location: Repop Hell
Been thanked: 2 times


Post by VintageTwin »

The only place you need to grease are both sides of the shoe bosses . Put a tiny bead on the scalloped edges of the (top) shoe end and wipe a film on the (bottom) shoe ends. No grease in the pivot cup. All the grease will do is pick up grit and become a coarse rubbing compound. A heavier amount of grease will separate and eventually drop to the bottom of the drum and wind up on the shoes.
You do not have the required permissions to view the files attached to this post.

Posts: 1925
Joined: Fri May 24, 2002 1:00 am
Bikes: 64FL 99FLHR 01FXSTD
Location: Mpls. MN.
Has thanked: 18 times
Been thanked: 83 times

mechanical drum brakes


Post by Panacea »

HI...I've had my rear mechanical brake jackhammer itself to peices, on two different bikes! My 49 and my 51,on the 49 not only did the torque loop on the backing plate shear of like butter but the arm also rounded itself on the square cam shaft. unfortunatly I only had rear brakes at the time,so me and my bike were on foot, only a couple miles....On the 51 I thought I was re-living an earlier experience, But having just bought the bike, and failing to do a complete inspection before my first ride,found out there was no axle nut on the bike,the rest was history...repeating itself. On the last post you made reference to how loosening the pivot stud with the brake on and re-tightening could make a diference,the pivot stud is in an elongated hole so the stud can move to find it's center. Thanks for the info on shoe fitment,I'll be fixing up this 51. I'm glad I found this site for very usefull information.PANACEA

Panhead Register Member
Posts: 865
Joined: Mon Aug 16, 2010 7:18 pm
Bikes: '46 Knuck. '57 Panhead, '59 Panhead
Location: Repop Hell
Been thanked: 2 times


Post by VintageTwin »

I've heard that several things can make the rear backing plate to frame anchor-cleat break off. The operating cam having too much freeplay in the bushing, and/or combined with worn down shoes will alow the brake to lock when the pedal's hit hard. The anchor cleats on the AM backing plates not being securely (flush) riveted and failing under brake chatter, and all four of the brake lining ends not being tapered and causing chatter. If I had an AM rear backing plate I wasn't sure of, I think I'd arc-weld a puddle over each of the anchor plate's flush rivets just to be safe.

Posts: 3337
Joined: Sat Jun 26, 2010 1:54 pm
Bikes: 1958flh 1969sporty,had a knuckle but sold back to original owner
Location: NEW JERSEY
Has thanked: 195 times
Been thanked: 267 times

Re: 1937-1957 Rear Brake- Fit Problem


Post by 58flh »

VT------I to had the same issues!---You have to place in drum & I would spin /with very minor brake applied!(minor)-take it all apart & start filing,Also I got a new plate from J&P cycles-V-Twin,I have a rivet machine I bought from an old school shop going out of biz. sale. I rivet all my shoes from center-out!--Basically I did the same as you had to, after everything is finally done!--ALWAYS apply brake before tightening axle! I have no lock-up problems/& I can lock them up to a skid-with no problems after!---Very good wright-up for the men!----58flh :!:

Posts: 285
Joined: Sun Nov 01, 2009 10:10 am
Bikes: '37 UL, '79 Frankenstein, '88 Sporty
Location: Oahu Hawaii
Has thanked: 7 times
Been thanked: 8 times

Re: 1937-1957 Rear Brake- Fit Problem


Post by Sir_Rat »

I guess I lucked out...I bought the complete rear brake assembly from V-Twin and it all fit fine. I still need to adjust and arch the shoes...I guess its just the luck of the draw.


Posts: 56
Joined: Sun Oct 16, 2016 3:18 pm
Bikes: 1947 EL, 1956 FL, 1958 FLH, 1986 FXRD, 2017 FLHXSE
Location: Chandler AZ
Has thanked: 3 times
Been thanked: 3 times

Re: 1937-1957 Rear Brake- Fit Problem


Post by PanScott »

In regards to the VT cast brake drum, mine had issues. I checked it for run out and it was at about .010". I turned it (actually bored)just to get a clean up that took about .020 on the diameter. When I put it on my 1956 FL The shoes rubbed the face of the drum where it was machined during manufacturing. This is afer I beveled the edges AND ground the brake linings flush with the VT replica cast shoe. Worst of all.... the end of the pivot stud rubs on the inner face of the drum as well.
The OEM backing plate is straight within .010", I had to straighten it so I know it is. The operating cam is new so is the bushing. and the pivot stud is assembled correctly. There is just not enough clearance in the drum. Back to the machine shop monday and I will take about .025 off of that face, hopefully that will be enough.

I definitely prefer the cast over the stamped drum but on my bike at least it is not "bolt in". Good thing I am a machinist.

Post Reply

Return to “Brakes”