The Tygon brake line worked well. It did not sweat or discolor. I used something like this:
good to know
To duplicate Bobby Byars GM conversion brake booster, the thing needs to be completely stripped and the stud pattern on the pedal side weld-converted from GM 3-stud SAE to a 4-stud metric to match DeTomaso's bolt pattern. Then reassembled and gold-alodined.
How Bobby did all this for the price he charged, I have no clue- and it had a warranty. The matched aluminum master cylinder was included. Inside one MS port is a 'keep-alive' check valve about the size of a very thick nickel for the front calipers, I always remove those since I had such a valve stick, once upon a time.
Otherwise, the only thing to watch out for (in shipping) is the vulnerable plastic valve on the pedal side is not not damaged. I never asked what model of GM it came off of- sorry. Mostly just check the booster OD to be sure it fits under the Pantera hood; not much clearance and the GM is slightly larger. Good luck-.
Let me ask a somewhat stupid question - WHY do we even need the booster? I know the GT40 and some other cars do not use one. Is it because they had the dual cylinder system?
I test drove a Pantera for someone not long ago and there was little if any vacuum to the brake booster. The car had good brakes. The brake pedal was quite firm and the calipers seemed to be working correctly. The hydraulics seemed healthy. Without power assist it took ample effort to slow the car and it took me by surprise how much the booster helps. I think I could drive a car without power brakes but I would need to be prepared for that type of braking. It's easy to try out. Just disconnect the brake booster hose and cap off the manifold or carb.
thanks Steve.
@lf-tp2511 posted:The vendor that offered the GM booster was Bobby Byars. He passed several years ago and the business is no longer active.
Larry
I'm sorry to hear that.
Are there different versions of Pantera brake boosters? Some seem to use a 3 bolt pattern, while others (My Deauville included) use a rectangular 4 bolt pattern.
All of them -at least the V-8s- use a 4-bolt pattern including the Mangusta, I believe. My '72 Pantera does. The 3-bolt pattern is typical of GMs.
Both of these are defined as "De Tomaso Pantera Brake booster" (Autoepoca)
This unit looks like it would fit on the Deauville,
This unit looks different, and the firewall bolt pattern looks like a 3-bolt.
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PIM has boosters for sale on the eBay right now.
I've tried running without a booster but found the pedal was just too heavy to be comfortable. I'm not saying it's not possible but with my calipers and CNC dual master setup, the pedal was just too heavy. I believe the root cause was that there isn't enough leverage with the Pantera's "short" brake pedal. With a longer pedal, such as SACC's aftermarket "racing" pedal setup, the pedal effort, without a booster, is reasonable.
Interesting info!
I decided to test my booster and hooked up a vacuum pump. It took me about 99 pumps to get 15 inches of vacuum that slowly bled down. Should it take a lot of pumps to get to 15 inches? Should I be able to get more than 15 inches with this setup?
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How well did it hold vacuum?
It held the vacuum and then leaked down very slowly.
You’re saying it took 99 pumps on that handheld vacuum pump?
I would say that makes sense – if you look at the difference in volume between the handheld pump cylinder, and the brake booster, it’s quite a big difference…
Rocky
I did not actually count the number of pumps that it took to get to 15 inches vacuum but it was a lot. I continued to pump once it leveled out at 15 inches and did not get any more vacuum. I am thinking there may be a leak. My next step is to get the car warmed up and then check manifold vacuum with the booster connected and then with it disconnected and the manifold capped off. The vacuum reading should not change. If it increases with the booster disconnected then there's a leak.
I don't suppose any of you has a booster laying around on the work bench, and can confirm the bolt pattern on the firewall side of the brake booster?
On the Deauville, the pattern is rectangular, 107,5 x 85 mm.
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What year is this? Just above there is a post stating that they all have 4-bolt patterns?