Ghia Road Course Setup

[fast Ed]

More great info again, thanks for taking the time to post!!

One quibble, when you change tire diameter, you lose half the difference in diameter on your ride height, not all of it (1.7" in your example given).


cheers
Ed N.

[FJCamper]

Hi Fast Ed-

You are exactly right on the ride height. Chalk that one up to brain fade.

And good to know someone is paying attention.

FJC

[superstar]

My 64 Ghia I has the stock drum brake system and stock rims. If I ran BFG radial t/a 155/80r15 street tires at the track, would the drum brakes have enough power to lock up the tires. If they did, would I need I more traction. If I changed tires to 155/r15 CR6ZZ Avon dot race radial, and the brakes would not lock up, would this be the better choice of tire for my brake tuning.

[Dale M.]

One thing you may want to try for brake tuning on a Ghia or a beetle if you want more braking on rear is to use type 3 drums and related brake parts on rear....

That is what we did to get some braking on this autocross car since front is so light....



Dale

[FJCamper]

Superstar, (Dale, really nice buggy)-

A stock '64 drum setup will do all you need for an autocross. But it is not enough for even a mild-engined open track car.

All your worries will go away if you just get a front disk brake conversion and stick in larger rear slave cylinders. The disk brake conversions are easy to install. The same VW-type kits, by the way, are sold to 356A and B Porsche owners.

You will love it.

FJC

[superstar]

I looked into the disk brake kit but decided to stick with the drums for cost reasons. By the time I got all the breaks working I had replaced absolutly every part of the brake system front and rear and spent about the same as the disk kit would have cost. In hind site I should have just converted to disk. I'll just live with the drums for now. Too bad I didn't find this forum a few years ago.

[fast Ed]

What is the opinion on doing the Type 3 rear drum conversion? This would be for my 67 Beetle, it already had the CB Perf. wide-5 front disc brake kit when I got it. I've seen it mentioned in a few resources that the Type 3 rears are a good alternative to rear discs on a car with a mild engine.

cheers
Ed N.

[Dale M.]

Type 3 rear brake give you about 30% increase in brake size.... You go from a about 9 inch drum to a 10 inch drum, and from a shoe that is about 1.5 inches to a shoe that is 2 inches wide....

Somebody who is a real stickler for details will probably come back with the absolute correct numbers but for practical purposes of discussion these are the sizes.....

The beauty of the conversion is its a bolt on modification with all standard VW parts.....

I can not say what this would do for a full size sedan (bug or Ghia) but for the buggy application it when from front wheel lockup and virtually no rear wheel braking to actual rear wheel braking.... Skid test went from virtually no rubber transfer to pavement at rear of car to a rubber transfer on rear about equal to front wheel transfer.... I know its not a great test, but in actual driving event I can really drop speed in braking situation with the larger rear brakes in relation ship to small rear brakes... This applies to my dune buggy, and can not vouch for a full sized vehicle....

Dale

[FJCamper]

Re: Type 3 Rear Drum Conversion

This is an effective and practical upgrade. It works because our VW's can actually use the larger rear brakes because of the rear-engine forward weight transfer.

Superstar -- a mild engine (90 to 100hp) in a lightweight Ghia will have you braking down from 100mph+ often. The Ghias handle so well you'll find yourself going too fast very quickly.

If you do nothing else, get drilled front drums. They'll fight off the fade. A cheaper cheater trick is to drill the shoes themselves and run air ducts to the front and rear brakes ported in via the brake backing plates.

Drilling the shoes vents the gasses back into the drum rather than out, but some of the heat wil escape through all the vent holes you drill in the back plates.

FJC

[superstar]

FJCamper,
Thanks for the suggestions. Drilling the drums and shoes would be free, just some machine shop time. Running ducts to the brakes was in my plans. I have a solution to mount the ducts to the body for air flow but I have not figured out how to mount the ducts to the brakes. I would think I need to cut a hole in the backing plate and weld a coller on it to clamp the hose to. Do you have a picture of this setup? What size duct would be best?
Thanks.

[Piledriver]

Just using the front wheel cylinders out back gets you ~95% of the full meal deal T3 rear brake setup effect.

There was an excellent thread awhile back on slotting drums...

[helowrench]

Just using the front wheel cylinders out back gets you ~95% of the full meal deal T3 rear brake setup effect.

There was an excellent thread awhile back on slotting drums...

When I put new wheel cyl in the rears of my 71 ghia, I unfortunately allowed the local "vw guru" to talk me into using the stock units.

A week into it, I was bleeding and adjusting, thinking that I had done something wrong, cause I lost braking power.
I went in and took a hard look at the removed cylinders, and found that they were indeed the front units.
moral: do your own research, once the decision is made, stick to your guns.

[FJCamper]

Brake Tricks and Traps

Hi Superstar,

2" ID for the duct to the brake backing plates front or rear. The fronts have to steer, of course, and need room and flex to do so. Typical inlet mount is a piece of exhaust pipe solidly brazed to the baking plate. Just leave enough room to hose clamp the air duct tube down.

Using larger than spec slave cylinders: In a perfect world, all things would fail in a logical or expected manner. In our world where gremlins reign, failures and problems are often hidden and double hidden.

Larger slave cylinders need more fluid, and (at best) change the feel/response of the braking system. At worse, if you have insufficient residual line pressure (a fault of the master cylinder), you get air in past the pistons on every use of the rear brakes.

Stock brake systems are designed to work right with stock brake parts, and when we start mixing and matching, strange things can happen. You almost need a fluid dynamics engineer looking over your shoulder (which we actually have at RetroRacing) with a calculator telling you where to find gremlins.

A standard 10psi residual valve to the rear drum brakes usually fixes all the pressure flux problems.

FJC

[84 IM Flier]

I'm presently rebuilding my 1984 Intermeccanica 356 Porsche replica (serious engine fire) and would like to install Koni shocks. Can you give me a link to a site that sells Konis (my Intermeccanica has a 1969 IRS pan).
Thanks
Ron
p.s. Many thanks for this awesome thread!

[Piledriver]

No fluid engineer required, I'm pretty sure VW had a few.

T3 rear wheel cylinders have a different part#, but they are 22mm... Just like late T1 fronts.
(late T3s had discs up front...)

You DO need a good master cylinder.

We are getting into brake balance, but certainly less than those same size rear cylinders pushing on ~50% more friction surface.
(meaning T3 rear brake swap)

Loads less expensive as well.