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Mon Oct 03, 2011 1:31 pm

Alright, I am a little confused about the use of front brakes on a rail buggy.

Background: I am in the process of build a decent rail for off road/trail driving. I intend to get it titled for street use as well. My initial thought was to go with four wheel brakes and a dual circuit master cylinder for a little added insurance. That way if one circuit goes, I don't loose all braking power. Then I started to think a bit more...

I have a few concerns about running brakes in the front of a light rail buggy. I am worried that the front wheels will lock up because of the lack of weight on them. If that happens, I lose most of my ability to get the car to turn. I have seen brake proportioning valves, but those are only good for single circuit master cylinders. Whats the point of running brakes on all four corners if you only use one cylinder. If something goes bad anywhere in the line, you loose it all the way around. That being said, relying on only two brakes in the back to stop also makes me nervous.

I see many examples of rear only and 4 wheel brakes set up. Two in the back? One on each corner? Im nervous any way I look at it.

Does anybody have any advice to help straighten me out?

Mon Oct 03, 2011 2:12 pm

I had a small 2 seater buggy that only had rear drums. It was mostly driven on street, but still went off road. The brakes where rebuilt, and bled properly, and stopped OK, so I thought. Its only scary when an 18 wheeler slams on the brakes in front of you, and your worried if you can stop in time.

I built a 4 seater with 4 wheel drums. I know its a little heavier,(not much) but I haven't had any problems with my front brakes locking up, even when wet. The buggy stops way better. Night and day difference.

You can still adjust the drums, so if your concerned about them locking, just adjust the front drums in. They won't have as much stopping power.

Plus when you hit the brakes, a lot of the weight is transferred to the front of the buggy, therefore that light front end becomes heavy.

Mon Oct 03, 2011 3:36 pm

It can get scarey real fast with only rear brakes. Panic stops will result in the rear sliding and very little braking effectiveness. You will retain steering control, but you do not always have a left or right escape route in traffic.

We drove rails on the highway in Mexico - It got even more exciting when a little drizzle came down on the oily road.

Mon Oct 03, 2011 4:20 pm

The line from the master cylinder will tee to the front brakes. Install the proportioning valve after the tee.
Paul

Mon Oct 03, 2011 4:33 pm

I had no front brakes on my street/trail buggy and never experienced any problems even after a few panic stops. Never felt like it wanted to swap ends.
Locking up the brakes leads to a loss of control no matter if you have two or four wheels sliding. In a light-weight buggy, the rules are a little different when it comes to brakes.

Mon Oct 03, 2011 4:43 pm

You will most likely not be able to register a buggy for the street unless it has brakes on all 4 corners.

Buggy disaster
Drum brakes are not heaver the disc brakes, I weighed all the parts for one side of a ball joint front end once. I was using Ghia brakes with the bolt on bracket conversion and the disc setup was heaver by a couple of pounds, here's a link to the post...
http://www.thesamba.com/vw/forum/viewtopic.php?t=322750&highlight=disc+brake+drum+brake

Casey

Mon Oct 03, 2011 5:16 pm

Paul Wilson wrote: The line from the master cylinder will tee to the front brakes. Install the proportioning valve after the tee.
Paul

1+ that way you can tune them on the street and then not run the fronts or make them almost useless for driving in sand or loose gravel. Front brakes in sand are dangerous.

Mon Oct 03, 2011 5:46 pm

Drums in front and discs in the rear gets my vote!

Mon Oct 03, 2011 8:26 pm

earthquake wrote: You will most likely not be able to register a buggy for the street unless it has brakes on all 4 corners.

Buggy disaster
Drum brakes are not heaver the disc brakes, I weighed all the parts for one side of a ball joint front end once. I was using Ghia brakes with the bolt on bracket conversion and the disc setup was heaver by a couple of pounds, here's a link to the post...
http://www.thesamba.com/vw/forum/viewtopic.php?t=322750&highlight=disc+brake+drum+brake

Casey

Oh, I meant the weight of my 4 seater, vs a 2 seater. My bad on not being clear. 8)

And thanks for the link. I think it just persuaded me to find a set of disks.

Tue Oct 04, 2011 8:58 am

earthquake wrote: You will most likely not be able to register a buggy for the street unless it has brakes on all 4 corners.

Casey

Ditto....

Dale

Tue Oct 04, 2011 10:31 am

Alright, thanks you guys. If I stick with the stock brakes on all four corners should I use the single or dual master cylinder?

Tue Oct 04, 2011 10:37 am

I prefer the dual cylinder master so you can set brake bias on the front and rear by adjusting the plunge depth of the rods plus you have some redundancy in case of leakage or failure.

Wed Oct 05, 2011 10:11 am

I didn't know you could adjust both parts of the cylinder individually. How exactly does that work?

Wed Oct 05, 2011 11:07 am

There's 2 definitions to dual master cylinders out there;
1. Production stuff is all internal, double cylinders in a single body. VW doubles are all one bore size and do not have any bias adjustment. They are no different than single masters as far as bias or adjustment. They are safer because you still have either front or rear pressure if the other fails.
2. Race stuff [aka tilton style] use two seperate masters and linkage. Either the masters may be different bore or the linkage between may be offset to alter the leverage.
There are pressure regulator type adjusters out there that limit the hydraulic pressure in a line. They are popular for reducing rear bias, but are not "linear" in their action and are very weird when used on front brakes. They rather suddenly stop building pressure at the setpoint instead of the gradual more pedal more brake feel we are used to with front brakes. They are cheaper than multiple cylinders and the pedals and linkage to control them.
With a very light front end buggy, much less front brake pressure [or more rear pressure] is a good thing.
With the old school Baja builds we used to reverse the wheel cylinders front to rear to change the bias. My old school Wampusskitty buggy still has this, along with T3 rear brakes, to alter the bias. It will lock up the fronts easily, but mostly when it is all so loose, like in deep sand, that the car drags down quickly anyway.
Front brakes and disc brakes are very important when you need to back down a loose hill, like when you run out of motor or traction. Especially if it is not entirely straight back down or you have turned a bit at the top. Rear brakes only [think parking brake only for example] and most drum brakes don't work here. Disc brakes don't care which way the rotors are turning. They are cheaper than T3 stuff now.
Your "budget" changes radically after one of those downhill thrill rides. I'll not tell how I know this....
Dennis

Wed Oct 05, 2011 2:15 pm

I had the VW dual circuit mast cylinder in mind. Since that one cant be biased, I would have to adjust the front drum brakes so that they don't engage as quickly as the rear ones? I know your normal supposed to adjust them so they just drag a bit, so would I have to have the front set up so it has no drag at all?

Wed Oct 05, 2011 8:13 pm

I run four wheel drums on a single master. No real problems if you know how to drive. Panic stops with a semi? I'm not that close.

They're horrible in the rain, fronts will lock up, ease off and reapply. Buggy Disaster probably doesn't have issues because he runs full size tires in the front. My skinnys slide in wet, gravel, sand, dirt, etc. They slide out on dry pavement if I accelerate during a turn.

So tire size/style will play a big part in your decision as well. If you run a comparable size tire in the front you probably wouldn't even need a proportioning valve.

Single or Dual cylinder? Again I don't think it matters or is necessary. Safety is important, but lets not bubble wrap the sun here. Its a rail, it's open, and the lines are exposed. If you don't do a little safety check on your entire rig often enough to catch a line before it bursts, you're probably going to end up stranded for various other things falling off, snapping, or melting way before a catastrophic brake failure occurs.

If I were you I'd spend the money and though on cutting brakes. If my fronts lock up going down a steepish hill I just grab the cutting brakes, that slows me enough. If I ended up having a terrible failure in my brakes system, I'll grab my cutting brakes:problem

That's what's called a win, win, win.

Thu Oct 06, 2011 5:20 pm

I'm running a 4-seat rail with 4-wheel stock drum brakes, Wilwood single master cylinder and a Speedway Motors prop valve mounted in the front lines- however, I didn't have to adjust the prop valve any, works fine with the original setting....
My one experience with a rear brake only buggy years ago was quite unimpressive, I would never do it...