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brake prep for moab.

skipnrocks

Well-Known Member
Joined
Oct 1, 2011
Messages
1,355
Location
Billings Montana
So the brakes in the kids buggy uses a remote slave cylinder kit to a hydroboost from a ford mustang. When the vehicle is running the brakes are decent, maybe al ittle tough to press but doable for a kid. But if you get in my buggy with the same master cylinder it is very easy to apply heavy brakes. So In prep for this years moab trip I wanted to trouble shoot this issue and see if I cant get it worked out.

The first tip that seems to be coming up is the pedal ratio. Right now I have probably 4-5 in from the pivot to the cylinder and then probably 10in after that to the bottom of the pedal. Apparently a 2-1 ratio isnt great so that maybe a good starting point. If I move the pivot 2-3in closer to the mc connection will that make enough of a difference.

Another thing I note is this, the pedal is dirrectly below the MC rod connector and also in line with the pivot at the frame. Where as with my other rig the pivot is back closer to the firewall then the pivot is out further and the pedal even further kinda like this /

SO with limited time to tweak and rework things and then be able to test them my questions are these...
1. If I just lower the pivot bracket closer to the mc a couple inches will that be enough to make significant change.
2. Is there a mechanical advantage to trying to get that top pivot point closer to the firewiall giving it more of / look.
 
1. Yes the closet the pivot is to the MC rod the easier it will be to push in, but will take more foot travel to push the rod in the same amount.
A longer pedal could accomplish the same but if your already close to the floor then you dont have that option.

2. I dont think there is a mechanical advantage in the angle.
 
So the easiest option for me to do would be to lower the pivot. I measured it ish and it looks like the pedal ratio is about 1-1 now which is probably awful. So maybe I could just move the pivot down keep the pedal from the brake mc down at its current distance and shorten the distance from the mc to the pivot.

That way I dont have to mess with my hard brake lines.
 
Well I got up at 3:30 am. Apparently I had had enough sleep. -4 outside (-20) windchill, turned on the heat from the app on my phone let it warm up for 30 min, went out and it was -4 out there. The drain on my furnace had froze solid. Lame

Well anyways I reworked the brake pedal from a 1.25:1 ratio to a 5:1 ratio and now it can be pressed easily by hand. Should make it pretty darn easy for the kids going forward. It is such a relief since if the buggy shut off for any reason on a hill it would be impossible to stop with the old ratio, running not too bad but off would never happen. I imagine it would be decently easy now, my other hydro boost buggy stops fine on or off with a 4.5:1 ratio
 
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