Brake booster delete (Page 2/2)
Yellow-88 OCT 03, 09:35 AM

quote
Originally posted by Dennis LaGrua:

If you do this booster delete and have an accident the insurance company will most likely deny coverage because you fooled with your cars braking system. First step; read your policy and call them to check. Speaking of mods, I doubt if there will be a problem with the S-10 booster as its looks stock.




Yes. This always comes up in modification discussions. If the other guy has a skilled investigative legal team, one could get wicked screwed. Many of us are already screwed in that case.
Yellow-88 OCT 03, 10:17 AM

quote
Originally posted by cartercarbaficionado:

yes I mean pedal effort. it's nice and firm and requires a decent amount of force to press down making the formula fun and responsive to drive but I have been told the fact that the pedal with the engine running refusing to move more than 1 inch before the brakes are at full lock is wrong for an 88
according to some fords I have I am correct. larger bore with smaller brake fluid chambers will move more with less effort for the same amount of braking.
all of my manual brake fords are 1.5 Bores and the power brakes are closer to 1.
yes I have done it but not on a fiero. I did it on my 69 toronado so I could fit a hydraulic clutch in a vehicle never intended for a clutch
that was just grabbing parts for a chevelle and making brakets to use the stock rods and such. other than that I did a power brake swap on a 1970 Nissan patrol using the small bore wilwood dual resivoir master on a fiero booster



With all due respect Carter, your getting the basics backwards.

" larger bore with smaller brake fluid chambers will move more with less effort for the same amount of braking."
Larger MC bore will move more fluid but braking force is related to the difference between MC bore and caliper bore. So a 1" MC bore and 2" Caliper bore is multiplying the force at the caliper. A 1.5" MC bore and 2" Caliper bore is multiplying less. The same thing happens at the peddle. Both are basically levers.

Increasing the MC bore from stock with the booster in place, will make for less peddle travel but require more effort, and that does make a better feel but still has that initial "lost motion" associated with the booster. It's the lost motion, remote control feeling that detracts from the feeling of being at one with the machine.

Personally, I like a "hard" peddle. I like my maximum effort to match the maximum braking force. I don't like lost motion in any control system.
fierofool OCT 03, 10:38 AM
You should be able to get some idea of the feel and how well the brakes work by disconnecting and plugging the vacuum line at the booster. Just do it in a vacant parking lot.

My Dad had a Ford truck with front disk brakes but no power brakes. Factory setup. It took a great deal of effort to stop the truck.
Yellow-88 OCT 03, 01:07 PM

quote
Originally posted by fierofool:

You should be able to get some idea of the feel and how well the brakes work by disconnecting and plugging the vacuum line at the booster. Just do it in a vacant parking lot.

My Dad had a Ford truck with front disk brakes but no power brakes. Factory setup. It took a great deal of effort to stop the truck.



Yes, that condition makes for a really nice pedal feel but has little effect on braking.
What I looking for is that balance between peddle effort and peddle travel. When it's right, the peddle immediately moves the MC piston so all peddle travel goes to moving the caliper pistons directly. With the booster the peddle is more like a valve that controls a "pressure chamber" that moves the MC piston with greater force the peddle "lever" alone can do. That's the feeling I'd like to eliminate.

Like Carter says, It's not easy. My first attempt was to increase the peddle ratio and decrease the MC bore. To do that required more room for a longer peddle but the wiper mechanism is in the way. I did manage to mock up a peddle assembly that increased the ratio from roughly 5:1 to about 7:1 using the stock peddle. Master cylinders are readily available in several bore sizes. Along with that was to space the peddles better. Ideally the steering wheel is between the brake and clutch peddles with a dead peddle for ones left foot. I shelved the project because of other priorities.

The MGB mentioned has about a 8:1 peddle ratio and a 3/4" MC bore driving 2 piston calipers (2.13") up front and drums in the rear. Peddle travel is about 1 1/2" before all 4 are locked up. Yes one does have to almost stand on the peddle to do that but locking the brakes is not a good thing. Ask any ABS system.

Currently Yellow has a 1" MC bore and SS flex lines at the calipers. Actually very nice brakes for an assisted system. But, Fiero peddle travel before I feel solid brakes is more than an MGB peddle when I'm standing on it. I think I'm just missing that connected feeling. And that giant booster is kinda silly in these little cars.
Dennis LaGrua OCT 03, 01:14 PM

quote
Originally posted by Yellow-88:


Yes. This always comes up in modification discussions. If the other guy has a skilled investigative legal team, one could get wicked screwed. Many of us are already screwed in that case.



The brake booster delete would be a very obvious mod to anyone doing even a cursory examination after an accident. The braking system would be a key place to look. Other items like exhaust are less noticeable and would be less suspect. You are aware of the downside, and of course you are certainly free to do as you please.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Yellow-88 OCT 03, 08:17 PM

quote
Originally posted by Dennis LaGrua:


The brake booster delete would be a very obvious mod to anyone doing even a cursory examination after an accident. The braking system would be a key place to look. Other items like exhaust are less noticeable and would be less suspect. You are aware of the downside, and of course you are certainly free to do as you please.




Yes, agreed. I certainly wouldn't want to see " ... failure to slow down due to apparent brake failure ..." on a police report. That's one of the contributes to the shelving. Now, almost 20 years later, I'm revisiting the concept back at the design stage. If I actually build a prototype and take it out on the road, I absolutely promises that I won't hurt anybody. That should be an Oath that Designer Builders should take.
Yellow-88 OCT 04, 11:18 PM
I think part of this peddle "feel" thing is the placement and spacing of them. The 4 peddles are, throttle, brake, clutch and dead peddle. So often in production cars we see brake and throttle at dramatically different heights. That's pretty much impossible to heel and toe. The clutch foot often has a rest but most often also at different heights than the peddle.

I think the ideal peddle setup would be 2 peddles to the right of the steering column and 2 to the left of it. A clutch peddle stop is needed to limit unnecessary movement and the dead peddle height can be accurately set. Step off the dead peddle onto the clutch with a foot rotation. I like a heel rest/locator for that foot. The break and throttle will need to be used simultaneously when breaking and matching RPMs for a downshift so both placing and shaping them is important. One beauty of manual brakes is the peddle movement before the driver feels them is much less. That makes it easier to heel the throttle and toe the brakes. Look at the peddles on some of the classic racing Sports Cars from the sixties.

Proper peddles are on the list for the Yellow 2.0 prototype. Yeah .... the list ...
Patrick OCT 04, 11:59 PM

Pedal.

That is all.