Upgrading Brakes and suspension - Page 3

dscott · #41 (**permalink**) 06-14-2004, 07:09 AM

Has anyone else tried the new pedal yet? I'm confused since I moved the pedal straight down it should have exactly the same angle as the old one. All I did was shorten the point between the pivot and the master attachment point. I've tried 2 of them here and they worked great. I'm sorry it didn't work for you Pete. If there is something else I need to change to make the new pedal work let me know. It's very easy to put a new angle on it. I thought I had this in the bag! Anyone else tried it yet?
Don

petek · #42 (**permalink**) 06-14-2004, 08:53 AM

Don,

I think the angle has a LOT to do with precisely where the new hole is drilled. If the hole is 1/8" off the pedal will be too far in or too far out. (Just guessing on my part.)

One thing that I learned from the use of the new pedal is that my brakes aren't a whole lot better with the mechanical advantage offered by the new pedal. The new pedal made the brakes easier to apply, but the car didn't really stop any quicker.

For a person with less strength in their legs the new pedal is great (if the height of the pedal is correct). For a big lug like me, the pedal change just wasn't worth the change in pedal height.

dscott · #43 (**permalink**) 06-14-2004, 09:08 AM

Pete, that almost leads me to believe there may be something else going on in your system. What size and type master are you running. The pedal ratio changes from 2 to 1, to 6 to 1. That should help in the effort which you said it did but it should also provide a multiple to the entire system, which should aid in the stopping force. That's what it did on the cars I tried. I could lock the brakes up easily. Let me know what your system is and maybe we can hit on something else.
Don

petek · #44 (**permalink**) 06-14-2004, 09:51 AM

Don,

I'll have to check my measurements again when I get home tonight, but I thought the original pedal was more like 4:1 and the new pedal 6:1.

I'm using the standard CR power-booster and master cylinder. Disc brakes all around, in-line proportioning valve. No leaks.

I have wondered if the rod from the booster isn't adjusted properly, I'll check the length the next chance I get.

dscott · #45 (**permalink**) 06-14-2004, 03:51 PM

Pete, the 3 problems I find alot with the rear disc setup is the rod between the master and booster as you mentioned. It should have 1/16 " clearance. If you have the rear disc setup with the Cadillac caliper the parking brake adjustment is very important because it sets up the proper distance for the pads to the rotor. If it's not set properly then you need to move the piston too far which gives a low pedal. If you have that setup give me a call and I can explain how to set it. The 3rd problem is with the same Cadillac caliper. The bleed screw does not sit at the top. The brackets don't allow it to tip back as far as it should to properly bleed them. You must take the caliper off of the bracket and tip the bleeder up to allow the air to escape. You only need to open the bleeder to do this. No reason to pump the brakes or apply any pressure, gravity will take care of it.
Don

petek · #46 (**permalink**) 06-14-2004, 08:23 PM

Don,

When I get a minute I'll check the rear brake settings. I think all that I need for the rear is to adjust the bias. Interestingly all of the pedals are at about the same height; clutch, brake, accelerator ... I like where the pedals are (except I'd love to move them forward about 6").

The brake is not spongy or anything. The car just doesn't stop like my Mini Cooper. (Then again, the Mini doesn't "go" like the Cobra either!)

I've got the measurements that I took of the original pedal and the new pedal:

original: 12" length (to center of the pedal pad), 3.75" from upper pivot to brake arm. Ratio: 12 / 3.75 = 3.2

new: 10.625 length, 2.25 to arm. Ratio: 10.625 / 2.25 = 4.72

So, unless I'm measuring something wrong or something, you're getting an improvement of 1.5 with the new pedal assembly -- a 150% improvement!

If I get a minute I'll see if I can sketch something that will give me an idea of the change in pedal height based on the positioning of the mounting hole. Since the pivot point is lowered, the movement of the mounting hole is going to have an effect on the angle of the pedal (because the brake rod distance remains the same). It's one of those things that I'm going to have to draw out to understand the angles involved.

Fred · #47 (**permalink**) 06-15-2004, 08:53 AM

Don,
How do I obtain one of these new pedals? In addition, your photo shows where to drill the new holes. Do you have actual dimensions of the hole location (how far below the upper hole)?

Fred

Jim Downard · #48 (**permalink**) 07-01-2004, 06:04 PM

Well Don,
I just don't know. I just recieved my pedal today and crawled under the streering wheel to compare, and my original pedal is exactly the same as the one you sent me, except that mine has 1/2" more offset than the new one. My old one is 12" long, and so is the new one. My old one is right at 2" from pedal pivot to master cylinder arm attach point, so is the new one. My pedal box only has 2 holes in it. My Cobra was purchased in April/May 1991. I think it might be one of the first cars off the line. I have never locked up my brakes. I have 11" rotors with GM calipers, and drums on the 8.8 rear end. I have on occasion tried to see if the wheels would lock up, only I chicken out that I might fracture the firewall first. I'm going to go ahead and return the brake pedal. I truely appreciate you sending these out free of charge, so actually, If you give me someone's address, I'll simply box it up and ship it directly to them, that way you will save on shipping to another person. Just get me an address and I'll send it out this Saturday, July 3.

Jim Downard

cobra427mnsi · #49 (**permalink**) 07-01-2004, 08:30 PM

Jim

I just received my pedal as well and there is quite a difference between the old and new. I got my CR in January of 92 so ours are close to the same age. I am surprised that your original pedal is the same as Don's new one. Maybe Classic used to use this new design in the beginning and changed their design for some reason. If that is true, I would really like to know the reason.

Anyway, I attached a pic of the old pedal and the new. The old measures 3 1/2" from the bottom of the mounting tube to the bottom of the pivot point pin. The new one is only 1 3/4". The new pedal is also shorter.

Paul
( I will try to attach the old pedal pic to this post and the new pedal pic to a second post)

cobra427mnsi · #50 (**permalink**) 07-01-2004, 08:32 PM

Sorry, I got the pics mixed up. This one is the old pedal the previous post has the new pedal.

Paul

dscott · #51 (**permalink**) 07-02-2004, 07:56 AM

I thought I had the pedal problem down pat but it's sounding like maybe I don't. CR must have had different pedals over the years. Jim, the pedal pivot hole must have been moved on yours already, maybe they did change it over the years but I don't know why they would make pedals with less ratio. I have replaced 2 pedals here and both worked great. I couldn't believe the change. I may have to look into this more. Has anyone tried the new pedal with good results?
Don

cobra427mnsi · #52 (**permalink**) 07-02-2004, 09:01 AM

Don

I haven't tried mine yet because I have the engine out of the car. It will be a while yet. I am anxious to hear of others experiences as well.

Paul

SWeeks · #53 (**permalink**) 07-02-2004, 11:46 AM

Don, I replaced my pedal with the new one a couple of weeks ago. I couldn't tell any noticeable change. I appreciate your efforts and the free pedal. I'm sure that you are on the right track because I have changed every brake part on my car and still have the same pitiful brakes that I've had since I built it in 1998.
I haven't given up, Just thinking about what to try next.

cobra427mnsi · #54 (**permalink**) 07-02-2004, 12:58 PM

SWeeks

What brake setup do you have ? Rear drums or disks ? I have 11" Granada rotors on front and 8.8 drums on rear. I find, if I want to make a quick stop (if that's possible), I pull on the emergency brake as well as step on the brake pedal. This helps with coming to a stop much quicker. This would indicate to me that the Mustang II proportioning valve is not feeding enough braking power to the rear drums. My next step is to get an adjustable proportioning valve .

Paul

Jim Downard · #55 (**permalink**) 07-02-2004, 01:33 PM

Well all,
I will crawl under the car tonight and get some measurements on the pedalbox, hole dimensions, etc., etc., etc. At least then we'll have the infor on the stuff that was originally sent to me.

Jim Downard

SWeeks · #56 (**permalink**) 07-06-2004, 03:55 PM

Cobra427mnsi,
Originally, I had nine inch disc on front, ten and a half inch disc on the rear, adjustable proportioning valve, Mustang II booster, and a NAPA corvette master cyl. that was recommended by Don Scott.
I now have Twelve inch (Master Power) disc with PBR calipers on front, eleven and three quarter (Rear from 95 Cobra) on the rear, same booster and proportioning valve, stainless flex hoses, and I replaced the master cyl. with another corvette cyl. I replaced the silicon brake fluid with Dot 5. I've always thought that the Pedal Ratio was the real problem, I've been looking for a pedal assy. from a donor car, but haven't found one yet. I was very excited when Don made the new pedal. I was somewhat disappointed when I installed it and test drove it and still have pretty much the same brakes I've always had. My Chrysler Pacifica and my Jeep Grand Cherokee, stop much better than my Cobra. My wife has a BMW M3, now thats BRAKES! Don, do you have any suggestions?

ItBites · #57 (**permalink**) 07-06-2004, 06:45 PM

Don't know if I should butt in here with everyone having so much fun, but I changed one thing on my Cobra with very high pedal effort and the difference is incredible!.

My problem is my pedal was too short, you'd like a pedal ratio of about 6.5 or better and I was stuck with about 4, due to space limitations in the footbox. Beyond that I have two tilton 5/8 diameter master cylinders (one for front one for rear) and 85 Corvette discs and calipers. I could have spent a lot of money for more piston area in the calipers (dual or four piston calipers). I could have gone from 12" rotors to 13" rotors. I could have tried to add power brakes (yuk!).

I changed the pads to a very agressive material. I went to Hawk Blue compound pads all around. These stop great. Pedal effort halved or less. Downside is more rotor wear and more brake dust, but I can change a lot of rotors before I pay near what it was going to cost me for a super-duper-hot-rod brake system.

Just my $.02... Could help someone out without changing the setup on the car.

dscott · #58 (**permalink**) 07-07-2004, 07:14 AM

I am just stumped for now. I've been working on this stupid brake problem for years and thought I fixed it. It sounds like I didn't. I talked to the owner of one of the cars I put the new pedal on to see how it's been working. He said the car stops much better and he can lock up the brakes now and he couldn't before. The setup on his car is the 11" up front, 11" rear disc, 1976 Corvette master, adjustable prop, stock Mustang II booster. Since it worked so well on this car and one other one I put the new pedal on I thought this was the fix. Sorry about all the work you guys have had to do with no solution. I'll keep working and try and come up with something different.
Don

rdorman · #59 (**permalink**) 07-07-2004, 08:26 AM

Don, perhaps I can help. Drop me a email.
Rick

rdorman · #60 (**permalink**) 07-13-2004, 05:50 AM

OK there CR owners. We need your help and in turn I beleive that we can help you!

For those of you that know me, you know I love to tinker with brake setups and have come up with a few tools to help work out the problems. When I bought my car, I had to mark it on my calendar so I could plan ahead to stop. NO MORE. It now stops on a dime and returns change! No exotic parts, no dusty rotor wearing pads, just basic off the shelf stuff. If I can help CRII be the same way it would be very satisfying.

Here is where you come in. Following is the basic CR setup that I am working from. For those of you with drums, sorry! Please verify these numbers:

wheel base, 94.5
weight with driver and half a tank 2600
weight dist 50/50
front and rear disc diameter 11"
peddle ratio (the new one) 6 to 1 (if your is different, please give layout and measurements)
front and rear calipers single piston (talking per side so sliders and fixed are the same deal, well basically!) 2.5" diameter piston
master cylinder front and rear bore 1.125"
Pad CF .4
booster diameter 7", diaphram please!
wilwood proportioning valve (dial or lever type?)

Any of this information you can confirm is a BIG help.

Couple of questions. With the proportioning valve full on and full off, what is the difference? For those of you that can actually lock the brakes, with the above setup, which lock first? Are you noticing that either the front or rear pads go away first? Any other observations you care to share?

Any one have a G-meter and can give me actual data?

So, please, help us all out! I KNOW that Don is committed to making CR the best product he can so this is a 'win-win' type situation.

Thanks
Rick