Disc brake conversion

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Master slacker
Posts: 86
Joined: Thu May 15, 2008 6:23 am

Disc brake conversion

Post by Master slacker » Sun Nov 21, 2021 1:02 pm

I'll very soon be getting my hands on the 1970 Bug my posts have referenced in the past. With that said, the first thing I'll be doing is working the brakes. This will not be a show car nor will it be a racer, but I do want something competent to bring the car to a stop. The direction I am going is a Ghia disc conversion up front and I don't know for the back. Possibly just staying with stock rear drums (move front drum cylinders to rears possible?). I'm also torn on the existing 2.5" drop. This is a convoluted mess of a situation as drop, track width, wheels, etc... play into it. Would plan to get a 19mm dual MC, btw.

If I ditch the drop spindles and go with an adjustable beam (or not, doesn't really matter), would it be better to cobble together Ghia brake components separately or simply pay once for a whole kit like at CIP1?

For the rears, 944NA would work fine but have a 5 hole pattern. Should I refresh the stock drums? Install larger cylinders? Or go with something like the 944?

Main goal is to keep it simple and relatively low cost. Thoughts?

Ian Godfrey
Posts: 186
Joined: Thu May 27, 2010 4:52 am

Re: Disc brake conversion

Post by Ian Godfrey » Tue Nov 23, 2021 1:36 am

my thoughts are that for most road use the stock Ghia calipers (or Varga replacements) and rear drums are a really good combination. I also like the look of the new Wilwood replacement caliper but I have not tried it. But I wouldn't buy other parts from EMPI without careful research.
I have tried larger wheel cylinders on the rear but unless you have skinnies up the front and fats down the back, the larger wheel cylinders unbalance the system.
I would definitely do the new 19mm master cylinder and I like braided brake hoses front and rear, which improve the pedal feel compared to rubber hoses. Use good quality pads and shoes and new rear drums (not chinese if possible).
the best handling is a full width beam, though with drop spindles it gets a bit wider, so choose your wheel offset carefully.
the CIP1 kit looks good value, Aircooled.net also has good kits with drop spindles.
let us know what you do and how it works out.

Bruce2
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Joined: Sat Oct 13, 2001 3:01 am

Re: Disc brake conversion

Post by Bruce2 » Tue Nov 23, 2021 9:29 am

What size tires will you be using, front and rear?

Master slacker
Posts: 86
Joined: Thu May 15, 2008 6:23 am

Re: Disc brake conversion

Post by Master slacker » Tue Nov 30, 2021 6:16 pm

Tires? I really don't know at this point. I aim to keep the front and rears about the same size and keep them under stock fenders. If I keep stock width beam (either adjustable or weld-in adjustment plates to stock beam), the track won't increase but I can lower it. Would Ghia spindles (?) and disc brakes widen the track?

Looks like I have more research to do on this because I only want to order each component once, not again and again based on failure of fitment. This will be a long time in the works as 1) I don't have the car yet, B) ordering / waiting takes a long time, and 4) I'm naturally a slow person with this kind of thing (I say it's because of my engineering mind, my wife says otherwise). Thanks for the help.

Ol'fogasaurus
Posts: 16996
Joined: Tue Nov 14, 2006 1:17 am

Re: Disc brake conversion

Post by Ol'fogasaurus » Tue Nov 30, 2021 10:48 pm

KISS is a good idea... up to a point anyway :roll: :wink: .

A '70 Model, here in the "states", has a BJ front beam. There are some advantages to using adjuster's on the front beam (one upper adjuster, two adjusters) especially with a BJ beam.

Dropped spindles do lower the car but with adjuster you have better control of just how much higher or lower the front end will sit. It is with the adjusters that you can use to change the amount of "spring" from standard springing to softer springing w/o changing to different torsion bar packs. For example: I'm running off-road (sand) in a dune buggy and am a "cruiser" on the sand so on my "in process build buggy" using a top only adjuster allows me to adjust the spring rate somewhat (no fuel tank up front which takes a lot of weight off the front of the toy) to drop the front end somewhat and change the spring rate a bit.

Soft non-metallic braided lines are OK and are easier to check their softness and non-swollen capability. It is the metal braided lines that I don't recommend: they look good but they can have several limitations such as checking their condition (such as swollen inner lines).

The dual MC can be done and I also have seen a hydraulic clutch setup with the stock MC setup but when adding the "juice" clutch setup things get really tight.

Lee

Bruce2
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Joined: Sat Oct 13, 2001 3:01 am

Re: Disc brake conversion

Post by Bruce2 » Fri Dec 10, 2021 2:27 pm

Master slacker wrote:
Tue Nov 30, 2021 6:16 pm
Tires? I really don't know at this point. I aim to keep the front and rears about the same size and keep them under stock fenders.
You should decide now, then you can choose brakes that work best.

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Chip Birks
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Re: Disc brake conversion

Post by Chip Birks » Fri Dec 10, 2021 10:03 pm

A 2 inch narrowed adjustable beam, dropped spindles and disc brakes is the ideal way to low the car with discs. CB sells a beam with bearings like your stock one, rather than plastic bushings. I wouldn't take off lowered spindles and replace with an adjustable beam. Spindles maintain factory ride, just relocate the axle up 2.5". Adjustable beams screw with geometry to get the drop, the 2 inch beam just helps deal with the offset of the spindle, plus brings your front wheel in slightly more. I've been over 120mph on my 3 inch beam with dropped spindles, the car handles just fine. I would not waste time gathering 50 year old ghia parts up at this point. That was a good option in the 80s, not needed today. Just buy an Empi or CB kit and call it good. The back can stay drums, your ebrake will be much better than the disc brake calipers that are available.

Bruce2
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Joined: Sat Oct 13, 2001 3:01 am

Re: Disc brake conversion

Post by Bruce2 » Fri Dec 10, 2021 10:32 pm

Chip Birks wrote:
Fri Dec 10, 2021 10:03 pm
I would not waste time gathering 50 year old ghia parts....
I wouldn't dismiss the stock parts. 50 year old Ghia spindles are superior to any aftermarket spindle you get today. The original VW spindles are 100% forged steel; aftermarket dropped spindles are cast iron. Ghia spindles are also a lot lighter, contributing to better ride quality.

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Max Welton
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Re: Disc brake conversion

Post by Max Welton » Sat Dec 11, 2021 10:51 am

The drop-spindles may maintain stock geometry but a narrowed beam has shortened springs. That means higher effective spring rates.

Now a drop-spindle that doesn't increase track would be the ticket.

Max

Ol'fogasaurus
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Joined: Tue Nov 14, 2006 1:17 am

Re: Disc brake conversion

Post by Ol'fogasaurus » Sat Dec 11, 2021 11:08 am

Going "nose down" can also mean that the beam's mounting angle has changed so now (does?) that have to be compensated for by the use of spacers/shims.

One thing about adjusters is that they can be adjusted to change the loading (spring rate of either the upper, lower or both torsion bars in the beam) to a certain extent.

Nothing is simple!

Lee

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