Sidecar brakes.

If you are positive that you have bleed them enough that ALL AIR is out of the system. There would be one of few likely issues, assuming the brakes worked properly before the sidecar.

Either the sidecars brakes are not properly adjusted and you need to adjust them tighter which in turn will use less fluid as they will have less distance to travel when applied.

Or your brake master cylinder does not have enough capacity to move enough fluid for both the rear brake and sidecar brake to work.

Also if there were a really bad rubber brake line for some reason that was expanding.

I am just starting into sidecars myself, but from a purely mechanical brake point of view, these would be the likely suspects I would check first.

Sometimes you have to really bleed the brakes a lot more then you think, be sure to use a clear hose on the nipple into a container and that end of the hose is submersed in brake fluid, otherwise air can and will go back into the caliper/slave cylinder as you tighten the bleeder.

Thanks I will redo the bleed tomorrow to check it. I was going to adjust the drum sidecar brake too. I fitted the larger harley sidecar master cylinder already. It is an old sidecar but was being used just before I got it so hopefully the lines are ok, but I will check.

Typically a drum brake requires far more fluid to actuate than a disc brake, so if the extra capacity Harley sidecar master was intended for a disc brake chair you might still fall a bit short. Hopefully bleeding will solve the problem. If not then maybe check to see if the Harley sidecar master was for a drum or disc sidecar wheel?

I installed a Liberty sidecar on my 05 Electra Glide last year. It has a disc brake operating off the rear master cylinder. I worked on cars for years but was surprised at the amount of bleeding required to get the firm pedal. Not that anything was at fault, it just took a fair amount of pumping. One note, try to stop short of letting the pedal go all the way down. When you do that you're pushing the master cylinder piston and seals into parts of the bore they have never been in before. If there is any damage to the bore, that's where it is.
Before mounting my sidecar I purchased the HD sidecar manual off of Ebay. There is no mention of a different master cylinder for the 99-2006, but then they only discuss the disk brake in the book I have.

Thanks for that, the larger brake reservoir is on most HD models, the standard one is just not big enough. It will operate the brakes but is wrong and can fail. I finally got the brakes to firm up, it took ages. The secret is to persevere. Lol.

Hi Jobiwan, what is the part number of the master cylinder you put on your bike? Or did you just add the reservoir to the front down tubes? I have a 93 Tour Glide with a 96 sidecar and I don't like the brake feel with the standard master cylinder. None of the manuals I have say anything about changing the master cylinder but it could be an option for me. My bike already has the reservoir located back under the right sidecover. Thanks, Dave

Is the purpose of the Harley reservoir change when adding a sidecar to add fluid volume, or to aid in checking the reservoir level? I know the addition of the lower front mount interferes with easy removal of the reservoir cover. I don't see the reservoir volume affecting "pedal feel" except in a case where one stroke of the pedal does not have sufficient volume to bring the pads and/or shoes out against the rotors and/or drum (i.e. drum brake shoes out of adjustment). In that case the reservoir volume allows you to quickly pump the pedal to get the pedal firm. But then the application of the pedal would never be firm until you pumped the pedal.

Correct, the reservoir volume is just as you say regarding actuation. The limiting factors on 'Feel' and actual mechanics are the bore length and bore diameter. The length of bore with proper linkage is directly proportional to how far shoes or pads will travel. The bore diameter effects how hard you have to press, as in how much hydraulic advantage is gained related to effort.

Look at a normal hydraulic bottle jack: a tiny bore diameter at the pump section to a huge bore diameter at ram section. If the pump stroke is long enough via length of internal bore and linkage then the smaller the pump bore the easier the effort to move the ram. This relationship is even more noticeable on older trucks like mine with a hydraulic clutch.

Markh00 - 2/23/2013 6:38 AM

Is the purpose of the Harley reservoir change when adding a sidecar to add fluid volume, or to aid in checking the reservoir level? I know the addition of the lower front mount interferes with easy removal of the reservoir cover. I don't see the reservoir volume affecting "pedal feel" except in a case where one stroke of the pedal does not have sufficient volume to bring the pads and/or shoes out against the rotors and/or drum (i.e. drum brake shoes out of adjustment). In that case the reservoir volume allows you to quickly pump the pedal to get the pedal firm. But then the application of the pedal would never be firm until you pumped the pedal.

Davet, I got an instruction leaflet off the HD website for sidecar attachment, just type in Harley Davidson sidecar attachment. The leaflet I used was for FLT series bikes from 1999 onwards, but there are files for other bikes. I put the reservoir on the front downtubes andtook the old reservoir off using the correct attachment to the rear brake equipment, there is a bar on older bikes downtubes specifically to take the larger brake reservoir. I mainly used the larger master cylinder because I heard the original does not have enough volume for both brakes, but it also is better because it moves it out of the way of attachment kits. Most of the parts are still available from HD, I did have to get the shaped brake hose from a vintage place ( HD dealer got it). There are a number of other mods the bikes require ( re-routed clutch cable, brake line 't' piece, etc). But I see many people have not bothered to do these. I followed the HD book fully and the combinations works a dream.

It is the remote reservoir, as detailed as a must in the Harley book, much more volume than the original, I nearly gave up on bleeding it, it took forever but is now working good. Both rear bike brake and S/C brake operate correctly and the pedal is firm.

I was pleased with the MMD reverse gear too, easy to install and makes operating the rig so easy without worrying about getting stuck. Lol.

Thanks for the info., for my combo of model years the manuals don't tell me to change the reservoir or master cylinder. I got a new wheel cylinder that I have to install on the sidecar and hopefully I can bleed the brakes well enough to get the pedal feel I want. If I can't I will look into the bigger master cylinder.