Brake Lever - "Mechanical Advantage"?

[Whites]

Brighter Pic. Master cylinder is removed.

Brake Lever

[Willow Racing]

That all looks very wrong to me, I could be wrong but I believe the picture shows a systme that is back to front as far as leverage to the master cylinder is concerned. I run two seperate master cylinders both the same. One feeds the front brakes (two calipers the other feeds the side and rear. My brake lever is around 7 inch long before the pivot point and about 1 inch long the otherside of the pivot point. When pushed back on the pedal, the 1 inch section moves forward. This is what pushes the two master cylinders pistons forward and activates the brakes. A bias bar between the cylinders two rods and attached to the end of the brake pedal then gives as much adjustment as needed. I'd take a picture if I could but don't have the nessacery . If you want to come have a look some time I live in Derbyshire just give me a call 07796948754 All the best Dave

[the gobshite]

That looks very odd, is the brake pedal in the on or off position?

Doesn't look like the pivots are right

[Whites]

It is currently in the on position, the master cylinder is removed, but fits at the top centre of the picture, you can see the bracket and bolt. The plunger of the master cylinder connects to the other end of the short lever. When you push the brake lever (towards the bottom of the pic) it pushes the plunger in the opposite direction (towards the top of the pic).

This looks like a well made brake assembly. I assume it is the original windle assembly? seems not from the replies so far.

[oldbelly]

We had the first of those Windles out on circuit early 94, ( practicing before the season started) Terry had made a right balls up and he will tell you the same . We thought we had air in the system as the pedal would travel back to the rear of the run Terry had made. We by then had been racing sidecars as a family for over 30 years but didnt doubt Terry and kept going with different ways of bleeding the bloody thing all to no avail. I decided to force the pedal below the little run it had and has on your bike and found the brakes worked perfectly , if my foot had been able to push the padal back 12". So we drilled a hole as close as we could to the existing one (where the lever finaly pushes the master cylinder and it felt good. I rang Terry to tell him what we had done , expecting a bollicking. Terry said great measure what you have and send me a diagram. We just missed out on the British Championship that year so it worked. What im getting at is if you put a pair of cylinders onto that lever system it should work by experimenting by moving the hole towards the main pivot. I would think you will need a little more mechanical leverage with two cylinders than with the origional Datsun type tandem cylinder. If you need any help give me a shout David . Yes that is origional Windle workmanship on your bike. Its too tidy to be anything else

[oldbelly]

See over

[Whites]

Thanks for the reply Geoff. The problem has never been the pedal traveling too far, it actually felt very good and went solid before it got near the stop, the problem is that there is far too much braking on the front wheel, it felt like the back wheels were "snaking", pivoting the weight between side and back under heavy braking.

The plan is to use the brake lever anyway, and attach it to 2 cylinders instead of the one.

We will find out at Val de Vienne if it worked or not I guess

[G JONES]

Brighter Pic. Master cylinder is removed.

Hi - I'm no expert - but the number of pivot points I would guess are going to make that brake setup very vague (for want of a better word)
The more direct you can get the pedal to M/Cyl the better - I'll post a pic of the brake setup on our new chassis - there's no M/Cyls fitted in that picture - but you can see where they go - we run as Dave - 1 cylinder to a pair of calipers on the front - I cylinder to Rear / Chair. (CP2623)
We use a 5/8" cylinder to the front calipers & 0.7 cylinder for the other 2 - which should give us a bit of bias (it does) - we can also put a bit of bias either way on the M/Cyl actuating rods.
The whole brake mounting setup can be removed from the bike for times when you need to tip the bike up to work on something.

[Whites]

We are looking at fitting something similar to this

http://www.ebay.co.uk/itm/Universal-Bra ... 35b6283c0e

We also have 2 calipers on the front (which will be fed from 1 master cylinder) and 1 each on back / side which will be fed by the other.

[oldbelly]

You wont be far away David you will be able tweak things with the hole positions to get the pedal feel near . Then you will have a brake bias to fine tune things further.

[G JONES]

We are looking at fitting something similar to this
http://www.ebay.co.uk/itm/Universal-Bra ... 35b6283c0e
We also have 2 calipers on the front (which will be fed from 1 master cylinder) and 1 each on back / side which will be fed by the other.

That wouldn't be a bad idea - if you can mount a pedal / lever to operate it efficiently it should be ok.
I looked at that type of mounting for our bike (didn't want to spend the money & I'd got the cylinders already) - but particularly wanted to keep the pedal / pivot / cylinders on one mounting so I can remove the lot as easily as possible - as it is now - I can take the whole brake system off the bike without needing to undo any of the brake lines - and if need be - we can bleed the brakes off the bike.

[ianw]

David, I think your complicating things for yourself
For many years I ran a servo with one, dual circuit master cylinder.
If as you say the front feels like it is " locking up ", two options, go for a harder compound on the front or cheapest option is to groove the front pads so you have less friction area in contact with the disc.
Unlike a Racing car or Kart you will never achieve the perfect brake balance because sidecars have one BIG difference over Cars & Karts & that is that a sidecar carries a passenger.
Depending on where the passengers weight is, over the back for a right or over the wheel arch for a left will influence the amount of braking, but that's a different matter.
I assume the disc on the sidecar wheel is a smaller diameter than the rear disc & that the rear disc is a (possibly?? ) smaller diameter than the front discs?

[Whites]

Hmm, I never considered a servo, for some reason I didn't think they were allowed.

I believe all the disc's are 11" diameter, I will confirm this today.

It wasn't that the front was "locking up", it was that it felt like the back end was "walking", shifting weight between back and side wheel, as if not enough braking happening on those wheels, its hard to explain :s

[ianw]

When you say, " walking " do you mean that under heavy braking the back end feels like it is moving left to right, right to left, snaking?

[Whites]

Yes Ian, snaking.