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Brakes for our fiberglass buggies. What's worked for you?
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joemama
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PostPosted: Sun Oct 02, 2022 11:35 am    Post subject: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

Dons Glitterbug thread sort of got hijacked with brake stuff. Thought a thread on brakes for buggies would be good? Ill start.
My driveway, were I park my buggy is very steep, and one car wide, and hooks. Because its a pain to back up it, I usually go head in, and back down. With dual master cylinder, and stock '67 drums all around, my fronts would lock up, the rears would continue turning, and kind of out of control backing down the driveway.
First thing I did, was put rear wheel cylinders on the front, and fronts on the back. Helped a little. I am currently still using the front drums, and installed Empi discs on the back. Im not ready to give a final opinion, as I think my disc pads are still wearing in.
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PostPosted: Sun Oct 02, 2022 3:07 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

On my street legal Dunebuggy I run late 4 lug drum brakes. I do not swap wheel cylinders, I run front cylinders on all 4 wheels. I have no problems stopping and I've been 91 MPH at the drag strip. With 145R/15 tires on the front if I brake hard they can lock up. If you have too much rear brake bias on a street car you can end up spinning around out of control.

On my Dunebuggy drag race car I run Bug drums on front and Type III rear drums. No problem stopping at over 100 MPH.
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PostPosted: Sun Oct 02, 2022 5:58 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

Street legal buggy, wide 5 drums up front, Type III wide 5 on the rear. I did swap wheel cylinders front to rear, but I don't recall the details right now - lots of others have posted about it.

Like Dave, I've had no problems stopping, and I've gone 99MPH on the dragstrip so far.

While 4 wheel drum brakes work for me, I did end up replacing all four drums, shoes, master, and wheel cylinders. Had I known I would be replacing everything going into it, I would have installed discs as the price difference is likely pretty minimal at that point.
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PostPosted: Sun Oct 02, 2022 6:37 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

The first comment I will make is that any brake information posted here needs to contain tire size otherwise the picture is incomplete. Tire size effects braking power and brake balance big time!
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PostPosted: Sun Oct 02, 2022 6:50 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

I would assume most of our buggies have plenty of tire patch on the ground. Mine are 175r15 fronts. 30x9.5x15 rear.
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PostPosted: Sun Oct 02, 2022 7:07 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

joemama wrote:
I would assume most of our buggies have plenty of tire patch on the ground. Mine are 175r15 fronts. 30x9.5x15 rear.

I wasn't thinking tire patch although that is part of the equation too. I am meaning tire HEIGHT. The tire has a mechanical advantage over the brakes and a change in tire height can have a make or break effect on braking power and brake balance.

This subject is very much of interest to me because I am in the process of changing tire sizes and upgrading the brake system at the same time. The previous set up was all stock standard '71 Beetle drum braking system with 22" tall front and 24" tall rear tires. Due to the short rubber the stock drum brakes were almost adequate for today's traffic. I say "almost" because I have been in a couple of situations now where those around me out braked my Buggy and things got interesting!

My first change was to go with the highly recommended and long standing EMPI front disc brake conversion kit. This was NOT an improvement in braking power! It takes MORE peddle effort now to stop the Buggy. I was not expecting that!
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PostPosted: Sun Oct 02, 2022 8:58 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

oprn wrote:
The first comment I will make is that any brake information posted here needs to contain tire size otherwise the picture is incomplete. Tire size effects braking power and brake balance big time!


That is a very important detail. The smaller tire spins the brakes faster, this rebalances the brakes. (Is it by the same amount?) A lot of beach buggies have large differences in front and rear tire sizes. On my buggy I'm running P175/65R14 front (23" tall) and P225/70R14 rear (26.3".)

Since most buggies also shift the overall weight distribution toward the rear that is another reason to shift more braking to the back. I have not weighed my current buggy, but I suspect the numbers from my first one are typical. That buggy had a front axle weight of 370lb. and a rear axle weight of 730lb. Stock is about 40% front, 60% rear. That buggy was about 33.6% front, 66.4% rear. I was told to generally expect the weight shift under braking to increase the effective front weight by up to 20%. It looks like VW was targeting about 61% of the braking to the front, so that about adds up.

One last point is that you do NOT want the rear tires locking up first on a tail heavy car. The back end tries to come around fast!
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PostPosted: Sun Oct 02, 2022 9:25 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

The mechanical advantage thing is real. I have never been able to lock up my rear tires (29" diameter), with drums or now with discs. I think my disc brakes will improve some as the pads wear in, but dont expect Ill be able to lock them up. I also think the pedal effort increased with the switch to discs.
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PostPosted: Mon Oct 03, 2022 4:48 am    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

joemama wrote:
I also think the pedal effort increased with the switch to discs.

That is exactly what I found! I found the same thing years ago when I put a set of type 3 discs on the front of my Super Beetle. Someone on here said it is because drum brakes are partly self-energizing. I believe it also has a lot to do with pad size, disc brake pads have only a fraction of the area that brake shoes do so require more pounds per square inch to have the same effect.

You will notice if you think about it that most cars with disc brakes have a brake booster. I have come to the conclusion that the switch to disc brakes is for low maintenance and fade resistance not stopping power. To recover our stopping power we need a smaller diameter master cylinder, larger area caliper cylinders, a longer arm brake pedal or a combination of all of them.

...or shorter tires!
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PostPosted: Tue Oct 04, 2022 5:03 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

vwracerdave wrote:
On my street legal Dunebuggy I run late 4 lug drum brakes. I do not swap wheel cylinders, I run front cylinders on all 4 wheels. I have no problems stopping and I've been 91 MPH at the drag strip. With 145R/15 tires on the front if I brake hard they can lock up. If you have too much rear brake bias on a street car you can end up spinning around out of control.

On my Dunebuggy drag race car I run Bug drums on front and Type III rear drums. No problem stopping at over 100 MPH.

I think this is an important subject to discuss in this forum and I hope to see more input. Including front and rear weight and tire sizes would be helpful, but any buggy owner input can be helpful.

My current buggy has rear wheel cylinders all around. That should be similar to the effect of VWracerdave, but with more pedal effort. Maybe not quite in my case because the rear brakes are only 30mm wide and have a 19mm wheel cylinder ('58-'67 size brakes.) My setup is not tested at speed but seems fine in neighborhood test during construction.

I have a back of the envelope calculation I use to estimate pedal effort. All else being equal a bigger bore master cylinder increases pedal effort -- smaller wheel cylinders increase pedal effort too. It is interesting how much the stock VW pedal effort varied between years, with the oval window Bugs being the highest pedal effort and the '65-'66 Bugs being the lowest.
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PostPosted: Tue Oct 04, 2022 6:34 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

I also think this is an important subject, and Im surprised how little participation there's been. I hope more people share their experience.
Here and there, I read complaints about how bad the stock drum brakes are, even after replacing all the components, and I often wonder if the experience would be better if the shoes were arched to the drums, like used to be standard practice. I have always thought the type 3 drums brakes for the rear would be the way to go, but now days its easier to buy discs.
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PostPosted: Tue Oct 04, 2022 8:13 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

I've been driving my buggy in almost every setup imaginable except off road for the last 18 years and over 70,000 miles.
It been run with a simple 1500 single port when I first got it on the road to a 1679 EFI turbo with close to 200 whp.

In that time I've had the stock drum brakes....then stock front drums and Empi rear discs and finally Empi discs on all four wheels.
With drums I could never get a decent pedal no matter how I adjusted them. It always had excess travel and you had to pump it once to get the pedal up higher.
When I built the buggy in 2002-2004 I installed all new wheel cylinders and a new Dual M/C so everything was brand new down to the lines and hoses.

Once I installed the rear discs it helped my pedal a little bit but it still had excessive travel. I installed the rear discs in September of 2014. In 2017 I installed the front Empi discs.
Once installed my pedal issues were all gone. I now had a very firm pedal and nice short travel on the pedal along with it staying nice and firm.

On a panic stabbing the pedal at lower speeds I can lock the front discs but it happens rarely.
Overall I really like the 4 wheel discs and once through the install bug I really like them. I also like being able to run chevy bolt patterned wheels which give me a nice offset in the rear even though I have wide tires.
My rears are 275/60-15 and the front are 155/80-15. Both sets are almost worn out.
The rears have over 35,000 miles on them and the fronts have almost 20,000 miles on them.
My right front has worn due to a bit of camber issues so I'll probably replace them all this coming spring/summer.
I'll probably increase the width of the fronts to some 195 series tires if I can find them in BFG T/A's.
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PostPosted: Wed Oct 05, 2022 2:08 am    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

Except for rear drums drilled for Chevy wheels, I am using all stock parts for a 1969 Beetle. Great pedal ... easily locks up all 4 wheels.
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PostPosted: Wed Oct 05, 2022 4:52 am    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

Q-Dog wrote:
Except for rear drums drilled for Chevy wheels, I am using all stock parts for a 1969 Beetle. Great pedal ... easily locks up all 4 wheels.

How tall are your tires please?
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PostPosted: Wed Oct 05, 2022 6:50 am    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

I have what I believe is stock brake on all four corners for my 61 chassis based buggy...

On auto X car I had stock 69 brakes on front and type III brakes on rear....

Never quite felt the need for disks...
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PostPosted: Wed Oct 05, 2022 7:23 am    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

vwracerdave wrote:
On my Dunebuggy drag race car I run Bug drums on front and Type III rear drums. No problem stopping at over 100 MPH.

At the risk of once again offending you Dave, the drag strip is a very controlled environment with no traffic, turns and very little for space restriction. Perhaps an anchor on a rope thrown out would do the job...

Ok just kidding!

Driving in traffic with multiple stops, on hills and curves is much much more demanding. I thought my brakes were just fine too... until I was in a multi car panic stop situation on a curve, down a mountain pass at highway speeds! Oh ya! that was an eye opener! Had to take the shoulder due to brake fade to avoid rear ending a newer car that didn't have brake fade.
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PostPosted: Wed Oct 05, 2022 7:47 am    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

oprn wrote:
Q-Dog wrote:
Except for rear drums drilled for Chevy wheels, I am using all stock parts for a 1969 Beetle. Great pedal ... easily locks up all 4 wheels.

How tall are your tires please?

245/60/15 rear, 205/60/15 front. Just bought 255/60/15 for the rear and 195/60/15 for fronts but haven't mounted them yet so I have no idea if the braking will change.
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PostPosted: Wed Oct 05, 2022 10:15 am    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

Tires / sizes front to rear are important, since they are what stop the car...

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PostPosted: Wed Oct 05, 2022 10:47 am    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

My first buggy ran stock 1964 Beetle brakes with a single circuit Bus master cylinder (built in reservoir.) The tires were 135R15 front and P225/70R15 rear. The fronts locked up easily and often. I drove it that way for about 6 years. It wasn't going to be ripping around any turns anyway, the front tires would scream if I tried to corner at a posted curve warning speed. This version had a front axle weight of 370 lb. and a rear axle weight of 730 lb.

Version 2 was the EV buggy, version 1. I lowered the floors starting just under the front seats 3 inches. That provided room for 3 Optima batteries on each side sitting low. 2 batteries up front where the gas tank was, 2 out back just behind the torsion housings and as low as possible without hitting the ebrake cables. The front tires where swapped to P145/65R15. The master cylinder was replaced with a dual circuit Bug model with Rabbit reservoir on top. Now the brakes required less effort despite the buggy gaining 320 lb. They also behaved very well, with good balance. It had mild understeer that could be turned into oversteer with a little brake or a little throttle. Severe braking would finally lock the front tires. The brakes at the wheels remained stock 1964 Beetle. This version had a front axle weight of 605 lb. and a rear axle weight of 815 lb.
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PostPosted: Wed Oct 05, 2022 1:02 pm    Post subject: Re: Brakes for our fiberglass buggies. What's worked for you? Reply with quote

VW sold millions and millions and millions of Type I, II, & III VW's with drum brakes. I drove my 1st VW when I was a teenager 40+ years ago and I've never had an issue stopping them. For 2 years I drove a Bus with drum brakes. All total I'm guessing I have over 300,000 miles driving VW's

Brakes stop the vehicle weight and speed. The tire must provide the traction for the brakes to work. Most of our Dunebuggies are 300-500 Lbs. lighter than a Bug so the stock braking system should be more than enough.

Way too many folks confuse manual brakes with modern cars that have power assisted brakes. I've noticed a lot of VW folks install disc brakes thinking they should act like power brakes. Manual disc brakes should not be any less pedal effort than manual drum brakes. My '74 Ghia has factory front disc brakes. I have to press the brake pedal just as hard as any Bug I've driven with 4 drum brakes.

If you're having issues stopping on twisty roads or hilly grades that is a failure of tire traction and not brake stopping force. If I can safely stop my Dunebuggy going 91 MPH at the track with stock drum brakes, you should have no problems stopping at 50, 60, or even 70 MPH on the street.

For some interesting info about stock drum brakes, wheel cylinders, and master cylinders look at the book written back in the 70's "Baja Bugs and Buggies"
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