Rear Disc Conversion Only

[luedtkec]

This may have been covered somewhere already but I could not find it, I am looking at leaving my fronts as drums and converting my rears to Ghia discs, and have a couple questions.

Will I need a bigger master cylinder to only run discs in the rear?

Will only discs in the rear cause an imbalance, should I just do all four discs? If I should do all four do I need a bigger master cylinder and valve, people seem to have mixed opinions?

I am looking at only converting the rear because I would prefer to have the rears lock up before the front offroad to try to push the car towards oversteer vs understeer.

1970 Beetle, 3x3 rear, cut and turn balljoint front, 1600DP, stock type 1 trans, 26" wheels front and 29" rear.

[Fiddlestyx]

Go drive a car and only use the emergency brake for braking. That's how it's going to be if you do this.
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1983 Vanagon Westfalia Air-cooled
1973 Super Beetle

[ashman40]

For safe on street braking you need to bias the braking towards the front. If you improve the braking you start with the front before you move to the rear. As the vehicle slows the weight is thrown forward unloading the rear. The harder you brake the less effective the rear brakes become (and more likely the rears will lose traction) while the fronts become MORE effective.

Even off road, when you brake is a straight line you don't want your rear brakes locking up prematurely. Locking your rear wheels while moving in a straight line will likely cause an unpredictable yaw to one side. You want controlled straight line braking in all conditions.


I think what you are looking for is something like this:
https://www.jbugs.com/product/16-2541.html

There are a few different versions, but these allow you to lock up one of your rear wheels on demand without compromising the normal braking in a straight line. Allowing you to brake hard before a turn while going straight and then to lock up the rears while in the turn to over steer. At least that is what I understand, I'm not an off-road kinda guy.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[TDCTDI]

Swap the wheel cylinders front to back, this is a common swap in the offroad forums, especially when using larger tires in the rear. I am using Ghia discs up front & the much larger typeIII drums in the rear. You might want to check out the HBB off-road forums for more advise
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Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[bluebus86]

More powerful brakes in the rear without an upgrade in the front is very ill advised. It will create a very dangerous handling condition, do not do it.

Bug On Safely!
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Help Prevent VW Engine Fires, see this link.....Engine safety wire information

Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022

[luedtkec]

How come you see many rails with brakelss spindles in front and discs in the rear? Is this because they are assumed to mostly be driving in a straight line?

[theKbStockpiler]

Rails are light so they don't really need front brakes which would lockup anyways because not enough weight is being transferred to the front when braking.

You don't want a lot of oversteer caused by rear braking but in contrast it is stereotyped that pushing through a turn is somehow better. Some oversteer is good.

A rear engine car is going to tend to oversteer in all situations so I personally would not try to totally eliminate it
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My beetle is not competing with your beetle. I have the yellow beetle in my town. There is a red one, a green one ......
Use all safety devices including a mask.

[Bashr52]

Not to mention Ghias do not have rear disc brakes. They are setup with front discs rear drums for a reason...

[pondoras box]

When the road gets wet and you brake hard the rear end will try to pass the front end, not a fun situation.

Here where we get the frozen version of rain, a lot of places will not put snow tires on the rear of a rear wheel drive vehicle unless you get fronts as well to avoid this very problem. You would think that the opposite would happen that it would keep the car straight but it will pull on way or the other and keep coming around.
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Looking for anything from Hal Casey Motors out of Hamburg New York, from license plate surrounds to matchbooks.

1961 23 Window (Bobo)
1965 11 Window (Zelda)
1965 13 Window (Lucas)
1957 Oval ragtop
1988 Cabriolet VR6 conversion
Plus a lot of other rusty junk

[TDCTDI]

The problem that the OP is experiencing is that the front brakes are locking up due to the fact that they have the skinny/smaller diameter tires up front with taller/wider tires in the rear. The taller tire size causes more leverage on the rear brakes which makes them less effective, especially when the brakes are already so front biased. Baja bugs, rails, & other VWs with staggered tire sizes need to have more brake bias transferred to the rear to avoid the fronts from just locking up leaving you going in a straight line with very little braking ability.

I do NOT suggest putting discs on the rear only but with the combination that the OP has, it is VERY necessary to increase the rear brake bias.
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Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.