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Brake on a Sputnik sidecar
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jaydmc
Posted 2/11/2015 2:51 PM (#82759)
Subject: Brake on a Sputnik sidecar


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I was asked about adding a brake to a Sputnik sidecar for a KLR by another user of this forum. As it is a long answer I decided to also post it for other people to use.

Getting a working brake on the Sputnik is possible, If you want to stay with the current drum brake a separate pedal would need to be fabricated that would sit next to the bikes brake pedal such that when you work the rear brake of the bike you also work the sidecar brake. This is tricky to get so that it feel right as the hydraulic brake on the bike has a lot less travel to the pedal then you normally would with a drum brake, if you adjust the pedal such that there is not a lot of travel to it you run into a problem in that Sputnik brake drums are seldom what we would consider "round" and as such you end up with a lot of brake pulsing.

A better way to add a brake is to change wheels which is also a good up grade as the weak link in the entire sidecar set up is the poor quality rim and spokes used on Sputnik sidecars.

So you need a wheel, two ways to go about doing this is either find or adapt a wheel that can work with the Sputnik's 17mm axle.

Most Japanese bikes like the KLR do not run a 17mm axle, Many BMW's did. On many BMW's you will find that they run a 25mm axle, in most cases there is a bearing that has the same O.D. as the 25mm bearing but has an I.D. of 17mm

So if you find a wheel that is narrow enough for the relatively short axle on the Sputnik you can run it on the Sputnik, However, this would be far to simple, there is a further problem. You must first remove the brake backing plate from the Sputnik swing arm, this is a shrink to fit part, some times they just fall off, some times you can beat them off with a hammer with out damaging them or if you know you are never going to use it again, damaging it is ok. If you do want to be able to use it again then a little heat from a propane torch around near the axle and it comes right off. Next issue is you must cut off the stud that anchors the backing plate.

Now that you have the backing plate off you will find that the area where it went over the axle is not machined so you can not run the bearing in this area so you need a spacer. The spacer needs to be narrow enough to only touch the center of the wheel bearing so a stack of washers will not work for this.

Another way you can do this is to change the axle out to one that will work with the wheel you want to use. If you go this route while it is tempting to run the KLR's front wheel, it has only a 15mm axle. I would not want to run an axle smaller then 17mm. It has been a long time since I have messed with the KLR wheel so my memory may be a bit off here but I believe that the KLR runs two different bearings sizes and there are no straight bearing swaps to go to a larger axle. Many Japanese bikes run a 15mm axle in the front and there is a bearing that can convert them over to 20mm however you would need the spacer that goes between the two bearings. To change out the axle with a axle from a bike you would first need to remove the stock sputnik axle. The best way we have found to do this is to cut off the shock mount from the swing arm as it is in the way. It is easy to weld it back on when done but now is also an exhalent time to up grade the Sputnik shock to a higher grade shock. How to up grade the shock can be covered at another time. Once the shock mount is out of the way bend the "ring" that holds the horseshoe clip from falling out, then remove the horseshoe clip and press the bearing out. Now the bad news, the part of the axle that goes into the swing arm is tapered so if you want to mount the axle the same way you would need to machine a tapered adapter. Of you could cut off the end of the swing arm instead and weld on an axle to the end of the swing arm however if you do not know what you are doing you could end up with an axle that is not safe to run due to the welding.

If we were doing this in our shop what we would do is cut the end of the swing arm off, use the custom axle we make for welding onto our swing arms, this axle is set up for 3/4 inch Harley type wheels.

Next issue is brake disk diameter, pretty much every bike out there the front brake is far stronger then you need and as such you end up needing to run a proportioning valve in the system. With the Harley wheel we run, we also make our own cast iron brake rotors that are about 7 inches in diameter and work out well.

Now assuming that you have gotten a wheel on the bike with a proper sized brake rotor you now need a caliper. This also needs to be a very weak caliper that also clears the spokes. We use a Brembo unit that we also laser cut a weld on plate to hold it to the swing arm. To install the caliper weld hook it up to either hydraulic pressure or shop air pressure to hold it where you want it to be, weld it and keep the pressure on until the weld cools.

Now that you have the caliper on the sidecar you need to hook it up to the bike. On the KLR it can be hooked to the rear brake pedal, or we make a brake pedal that has its own master. We also offer a quick disconnect coupler should you want to tie it onto the bikes hydraulic system this allows the sidecar to come on or off with out having to bleed the brakes every time.

Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
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IndSlim
Posted 2/11/2015 7:57 PM (#82767 - in reply to #82759)
Subject: Re: Brake on a Sputnik sidecar


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Posts: 98
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Location: SW Ohio
I don't see your quick disconnect coupler on your website Jay. Details?
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jaydmc
Posted 2/12/2015 10:38 AM (#82778 - in reply to #82759)
Subject: Re: Brake on a Sputnik sidecar


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We do not have a lot of items on our web site that we can do, if every thing was on the site it would overwhelm people looking at it. The coupler is very similar to the coupler used on shop air lines except that it has check valves in it so that you need not bleed the brakes when you use it. The couple has 1/8 inch pipe threads, we of course also have adapters and make brake hoses.
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
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VLAD
Posted 2/12/2015 1:35 PM (#82781 - in reply to #82759)
Subject: RE: Brake on a Sputnik sidecar



Extreme Veteran

Posts: 411
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Location: DENVER, COLORADO
Did you try to plumb hydraulic cylinder (like slave clutch cylinder) attached to braking plate of sidecar and working with drum brake?
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jaydmc
Posted 2/12/2015 1:45 PM (#82782 - in reply to #82781)
Subject: Re: Brake on a Sputnik sidecar


Expert

Posts: 1492
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It could be done with a clutch slave however you would end up with some thing with the design qualities that Rube Goldberg would have been proud of.
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
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claude #3563
Posted 2/12/2015 4:13 PM (#82784 - in reply to #82782)
Subject: Re: Brake on a Sputnik sidecar



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Posts: 2471
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Location: Middleburg, Pa
I agree that a separate ‘pedal’ is the simpler way to do it. However, I do not like the pedals side by side but rather to have the second pedal lower with a rod going over and under the stock pedal with an adjustor on it so when you hit the stock pedal it activates the sidecar brake. This also prevents one from hitting just the sidecar brake by mistake which can make things a little hairy at a bad moment. If they want to do it on purpose it is possible but it won;’t happen by mistake. An adjustment is there to balance brake bias between the bike and sidecar under the stock pedal. Yes, steep downhills can be tricky with no brake on the sidecar when trying to maintain a slow speed. They can be tricky with a sidecar brake also depending on the steepness of the hill and weight of or in the sidecar. I just logge d on to sidecar,com and it has been a while since I have been there.
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Claus
Posted 2/14/2015 10:32 AM (#82820 - in reply to #82759)
Subject: RE: Brake on a Sputnik sidecar


Regular

Posts: 57
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Location: Northern Germany
Jay is right. When I saw how poor the sputnik sidecar was manufactured I decided to cut the whole swingarm off and make a new one that would take up the brake.



After doing that I had to reinforce the connection point of the swingarm and I welded on a new connection for the new shock





Then I let the whole thing be sandblasted to get rid of the rust and stains and painted it.



It was one of my early works but the rig bekame pretty rugged and is still doing 15k mls every year.
Due to the costs of the build the customer ran out of money, so the paintwork is some odd colour painted with a brush by himself. But I like the rig and am always looking foreward to testride it when it´s here for beeing serviced.





Edited by Claus 2/14/2015 10:43 AM
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