I don't know how else it could've been interpreted. Did you not get the connection between weak legs and the need for a larger power brake booster? It was just a joke, and I thought the picture was perfect.
i guess i can be quite dense at times. Anyway, the correct length of the Fiero rod to cut and thread for my 84 Fiero and for the 95 GMC Sonoma power booster was 5 1/8". i did some welding and now its the correct length and the pedal height is the same as the clutch, and the brake light is off, unless i tap on the brakes and the light comes on immediatly. Just what i want.
Lets do some math (maybe i have weak legs, but hey, i'm getting old and my brain functions fine) Force=Pressure * Area lbs force = lbs/in^2 * in^2
the ratio of lbs force new booster/lbs force old booster = Pressure of Vacuum * Area of new booster / Pressure of Vacuum * Area old booster
Since the pressure of the vacuum for both booster is equal, the pressure terms drop out (anything divided by itself is 1)
so we are left with
the ratio of lbs force new booster/lbs force old booster = Area of new booster / area of old booster
Area = Pi * radius ^2 . so Pi divided by Pi drops out ( anything divided by itself is 1) . So we have
the ratio of lbs force new booster/lbs force old booster = Area new booster/ Area of old booster = r^2 new booster/r^2 old booster
Old booster is 9" and new booster is 10 3/4" so R of old booster is 4.5" and R of new booster is 5 3/8"
R^2 of old booster is 20.25 and R^2 of new booster is 28.89
So the ratio of lbs force new booster/lbs force old booster = 28.89/20.25 = 1.427 . But i can't measure that accurately with my equipment so rounding off we get a ratio of 1.4
In other terms the S10 booster is 40% more powerful than the old booster. But you knew that didn't you?
jon
------------------ Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.
Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.
I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun!
i've been enjoying my "new" brakes, but one thing that i don't remember anyone else mentioning was the different size vacuum hose between the 84 Fiero and the 95 GMC Sonoma
i had to reuse the Fiero banjo fitting and shorten the hose to fit the larger booster. Would the smaller diameter Fiero hose (and the longer run from the engine) make the recovery time longer ?
Are you referring to the little plastic one way valve? If so I just swapped them over from fiero to the s-10 and have seen no ill effects. As for the recovery time, sure it’ll take a little bit longer but not by that much at all, once the booster sees vacuum the likelihood that you will be able to drain it faster than it builds is near non-existent (assuming everything is functioning properly)
Are you referring to the little plastic one way valve? If so I just swapped them over from fiero to the s-10 and have seen no ill effects. As for the recovery time, sure it’ll take a little bit longer but not by that much at all, once the booster sees vacuum the likelihood that you will be able to drain it faster than it builds is near non-existent (assuming everything is functioning properly)
On my 87GT, I also had to swap the old check valve to the new brake booster as well. I used the Tuff Stuff booster with the Rodney Dickman end. Actually two screw on ends come with the Tuff Stuff (Hurst) booster but they are too short. They could be extended with a long nut and a small length of threaded rod but I thought that keeping only one attachment point was beneficial. BTW by tightening with some Red Locktite on the threads I cannot see the end coming off. If I was that worried I would tack with mig welds there. Best brake upgrade ever.
------------------ " 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 "
That is a great video. Funny the Motor Week guys got the rears to lock up on a stock Fiero, I have never seen that happen. Nice to see a video that clearly shows the kind of results a mod can give you.
------------------ 86 GT built 2.2 ecotec turbo rear SLA suspension QA1 coilovers on tube arms
Thanks for the positive words guys! I would like to find a way to adjust my brake bias to add a little more in the back. I think it could stop even faster if the bigger back tires are pulling their weight.
[This message has been edited by liv4God (edited 01-27-2020).]
I am wondering why the 65 mph stop took a shorter distance with the big booster.
I'm thinking that with the big booster, your leg (and the booster) are reaching the maximum braking force in less time than with the stock booster.
Less time spent near 65 mph during initial brake application would lead to shorter stopping distance.
At 2:30 in the video, with the stock booster, there are no tire squealing sounds (as with the big booster at 3:16), so it seems like maybe you weren't pushing on the brake pedal hard enough with the stock booster.
[This message has been edited by pmbrunelle (edited 01-27-2020).]
I am wondering why the 65 mph stop took a shorter distance with the big booster.
I'm thinking that with the big booster, your leg (and the booster) are reaching the maximum braking force in less time than with the stock booster.
Less time spent near 65 mph during initial brake application would lead to shorter stopping distance.
At 2:30 in the video, with the stock booster, there are no tire squealing sounds (as with the big booster at 3:16), so it seems like maybe you weren't pushing on the brake pedal hard enough with the stock booster.
Locking the wheels and sliding actually makes stopping distance longer. My goal in the test was to push the brakes as hard as I could and modulate it when necessary to avoid locking up and get the shortest stopping distance. With the stock booster I could hold it full pressure the hole time until the last bit and then let up slightly at the end. Thus being easy to avoid locking up and maximize the braking performance. The big booster locked up easier so it was harder to avoid locking up. This decreased the effectiveness of the big booster and is the primary reason that both boosters had the same stopping distance in the 35mph test. If a driver could do a better job modulating the bigger booster to avoid locking up it should stop even faster. That being the concept behind antilock brakes. (also avoids losing control in a slide) The function of the bigger booster is giving more force into the master cylinder. When added to my foot's force that becomes a force great enough to lock the wheels faster than when with the stock booster. That's why it helps decrease the speed better at first, but also leads to locking up faster than before even with the same amount of force from the driver's foot.
In reading the beginning of this thread, Phil stated that he removed the 12" Vette discs because he didn't want to carry a 16" spare wheel up front. Somewhere I read that a Fiero guy came up with a fix for this situation; The spares from certain Subarus (Around 1996)use a 16" wheel...they will fit over a 12" brake setup. The hub hole in the middle needs to be routed out slightly and the wheel/tire fits in the spare well NOT taking up any excess room. Tire size is 115/70-16....This allows you to have 12" discs and a normal spare.
As an added note, I have my battery mounted up front and the tire fits over it and locks in place as normal.
[This message has been edited by cvxjet (edited 01-28-2020).]
I use a Willwood 260-11179 pressure reducing valve on my front brake circuit in conjunction with a stock prop valve that is disabled by removing the rubber valve that is part of the threaded in spring assembly. So the prop valve in my car only acts as a fluid junction.
Removing the rubber valve gives an approximate 50/50 split to front and rear wheels. Doing this mod alone will not result in improved braking.The rears will still do very little and the fronts will still lock up prematurely. I know this because I tested my car with the stock prop valve disabled.
The problem is that you need to increase the pressure to the rear brake circuit. Hooking the Willwood valve to the rear circuit will only give you the ability to reduce pressure to the rears, the opposite of what needs to be done.
So with the prop valve disabled I put the the Willwood valve on the front circuit and I have it setup so that the rears have more braking force but still do not lock up in a panic stop. The fronts will lock up in a panic stop but not until you are going fairly slow around 10 mph.
So I am happy with my setup. It is what you would call a static setup in that the pressure front to rear increases at the same % no matter how hard you push the pedal. There is no auto proportioning going on. So far I have not had any reason to change the setting of the Willwood valve. My car is not winter driven.
I am not saying that people should go out and replicate what I have done. In fact I do not recomend it at all. I just provide this as information only.
The Thread where I have described what I have done and lots of discussion about the prop valve problem is here:
What started me down this path was once I put on a lebarron brake kit front and rear , the braking improved but I ended up with right front lockup. Too annoying for words.
------------------ 86 GT built 2.2 ecotec turbo rear SLA suspension QA1 coilovers on tube arms
Thanks for the ideas on the proportioning valves. The biggest issue seems to be the disparity between the brake line coupling sizes. I think I can make it work, trying to decide which option is the best. Using adapters or refitting the lines with the necessary couplers.
[This message has been edited by liv4God (edited 02-05-2020).]
Reuse your current push rod that is between the booster and master.
Thanks! If only I had kept it. Anyone have one to sell?
Edit: Hmnn, I just had a look at page 5 of this topic. There is a photo of a pair of push rods that shows a different version of the S10 booster pin. Also, the poster recommends using it instead of the stock pin.
[This message has been edited by PePe-LePu_For_2 (edited 12-09-2020).]
My only criticism of the video is that it took me far longer than 1 hour to install the brake booster. i worked on it for several days - it took me over 1 hour just to get the last nut on the booster to the firewall.
Still this mod is worth it! One of the best things i have ever done to my car.
jon
------------------ Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.
Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.
I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun!
My only criticism of the video is that it took me far longer than 1 hour to install the brake booster. i worked on it for several days - it took me over 1 hour just to get the last nut on the booster to the firewall.
Still this mod is worth it! One of the best things i have ever done to my car.
jon
I don't recall how long it took me to do this years back, but I agree with your conclusion - every time I drive the Fiero I am reminded it is an awesome upgrade IMO....
My only criticism of the video is that it took me far longer than 1 hour to install the brake booster. i worked on it for several days - it took me over 1 hour just to get the last nut on the booster to the firewall. Still this mod is worth it! One of the best things i have ever done to my car. jon
So, there's a video describing this process of what is entailed in swapping the booster somewhere?
i got my 87 fiero a few months ago.it surprised me how much pedal pressure it took to stop it.MUCH more than my other cars.so i ordered brand name rotors and pads from rockauto.[plus rear calipers since my car had front calipers front and rear].i installed the rear brakes and will install the front brakes though i hate greasing bearings.i may still do the booster upgrade.
Hey guys... I wanted to quote this comment from our good old friend Tony Kania who now appears to be banned (don't remember what happened).
The question I have is... how do you know what kind of bias you should have? The last time I did anything remotely SCCA was way back in the late 90s... and it was only a few sessions that I showed up for that allowed me to do a run in the cones. That was obviously over 20+ years ago.
I'm building out a Fiero that will certainly exceed stock brakes and handling, but not by much. I'm looking at probably ~175hp / 220 ft-lbs of torque.
I've upgraded my car with cross-drilled rear rotors just to prevent overheating, but I've also installed the Grand Am brake upgrade kit, along with steel lines and steel braided brake lines.
Don't make fun of me here... but I used a proportioning valve a LOT... in the COMPUTER GAME Need for Speed - Porsche Unleashed. Hahah. So I understand the concept of increasing brake bias to one way or another. I realize the physics weren't real, but I always increased front bias because the Porsches (except the 944 / 928) would always have the rear-end swing out, and it made it easier to drive at the extreme limits when I pushed the car (in the game).
Are there any good tutorials (YouTube) that anyone knows about that explains concisely the dynamics of braking and handling as it applies to oversteer and understeer? I understand what each is, of course... but what I'm asking is... is there a tutorial that explains say... if you install a rear-sway bar... this reduces understeer (but increases oversteer), for example? And as it applies to a brake proportioning valve... (while also understanding brake dynamics ... e.g., if you let up off the gas in a mid-engine or rear-engine car, the back-end is likely to come out.
I'm a bit more comfortable with ever so slight understeer, but with the things I've done to the car (larger rear wheels, poly bushings, larger sway bar, etc...) I really have no idea what I've done to the car. I made most of these changes when I was much younger, and I didn't quite understand any of it back then. I'd prefer slight understeer, but also want to know that my brakes are properly tuned to advantage the changes I've made.
Did you not get the connection between weak legs and the need for a larger power brake booster? It was just a joke, and I thought the picture was perfect.
