I'm trying to get a feel for you and Paul about force and travel...math is one thing, but I'm not always sure what the answer means. you both seem to like what you have and you should have pretty different pedal feel....I'm guessing yours is nearly the same force as stock, if my math is right. I'm about 95% ready to go ahead and pull the booster out. It looks like it will be no problem to keep the 90 degree linkage so there spare tire space can stay. I'm also pondering variable ratio linkage thinking if I plan well I should be able to keep both the travel and force in a range I like. So I'm trying to decide if I want to order the tilton cylinder mount or not depending on exactly how I want the final linkage to look/act.
Mike, I do not know if this will help, but I have pressure guages on both front and rear brake lines to help dial in threshold braking and brake bias. I find I am generating about 300 psi at that point. When driving on the street, I use very little brake pedal pressure with very little pedal travel compared to a stock setup. When I drove my friend's 308, I started to panic when his brakes did not begin to grab compared to what I'm used to.
I would have to do back-to-back testing between my car and a stock 308 to know for sure which one has more pedal travel but like I said before: I think the travel on my pedal is pretty good. It does require more force though but I don't find that objectionable. It probably makes pedal modulation easier. I have a variable ratio in that I welded a piece of flat stock to the pedal journal parallel with the pedal arm so that the Heim joint attatched to the linkage fits in a fork and also reinforces the pedal arm. I left room for the option of drilling holes lower and higher through the pedal arm and and the parallel piece to increase or decrease leverage.
Thanks guys. Wil, by variable ratio what I meant was designing the linkage so that that the mechanical ratio is about 3 or 4:1 when the pedal is up and goes to about 5 or 6:1 as the pedal moves down. It might no be worth the bother though, it sounds like both you and Paul are happy with what the simple likage does.
Paul, I looked at the coleman site and it says the series IV calipers have 2"/1.875" pistons. Is that what you have do you know? Piston size is key to the meaning of the pressure. Paul/Wil - are you guys running the tilton 74 series masters or the 75? The 75 are $20 more, but they claim reduced pedal travel due to tighter tolerance and ports the close faster. Just wondering if either of you tried them. I think I'm just going to buy the tilton balance bar assembly and make the cylinder mounts/linkage. I think it will be a little neater for what I want to build and gives me more options. I'm just trying to decide where I want to start with cylinder sizing. I'm thinking now is the time for SS line since the more rigid line will reduce pedal travel too, so I can add a little more mechanical ratio to the system.....every little bit helps.
I have the standard Tilton "universal" master cylinders, which I guess are the 74 series, but they seem to work fine. I knew the 75 series were shorter but didn't realize they were quicker acting. You might want the shorter ones anyway if you're determined to mount them sideways. I'm not too worried about the lack of a spare tire and really like weight reduction and the accessabily to everything in the front "trunk" with no tire tub. I installed stainless braided teflon lined racing brake hoses on my car but you're not talking about stainless hard lines are you?
My tire and tire tub are out too (to make my radiator fit)....but I get nervous taking it on trips. I keep thinking I'm going to mount a dounut up there somehow..... no, changing the hard lines, just replacing the rubber with stainless braided teflon to get the spring out of the system.
Actually I'd forgotten. I also took out the spare tire tub to get my fatter aluminum radiator to fit. Someone should develop an inflatable tire/wheel assembly that would come in a package about the size of a car battery. Even if it was only good for one use I would buy it!
Has anybody tried just bolting it an aftermarket pedal assembly? It seems like the other options endup with extra parts and pivots. I printed a drawing of a tilton pedal assembly and got out my tape measure and it seems like it should fit. I might get one and try it.
I've got the standard "overhung mount" aluminum dual pedal assembly in another car but I had a lot more component locating freedom there since it's a scratch built car. To me it made a lot of sense to install Tilton's remote set-up in my 308. It allowed me to leave the clutch linkage and brake light switch untouched and the stock pedals wound up the same distance from the seat tracks and only about 1/4" (6-7mm) higher above the floor due to the aluminum lower mounting plate for the remote tandem master cylinder assemby being sanwiched under the stock pedal box. I have an admitted habit of over-complicating things (evidenced by my supercharger installation) but I really think Paul's set-up is the simplest solution and I'm glad I copied his.
You're probaly right that keeping the install easy is my best bet...particularly with all the other stuff I've got going on right now. Do you recall which remote adjuster works with the tilton remote pedal assembly? The drawign doesn't appear to say and they have 3 versions 3/8, 7/16, 1/2? Are you running a proportioning valve too? Martin says yes for street cars in one of the posts way back that made sense, so I'm planning on an adjustable one too. Just curisous what you did.
Mark, "Paul, I looked at the coleman site and it says the series IV calipers have 2"/1.875" pistons. Is that what you have do you know? Piston size is key to the meaning of the pressure." -Yes "Paul/Wil - are you guys running the tilton 74 series masters or the 75?" -74 "Do you recall which remote adjuster works with the tilton remote pedal assembly? The drawign doesn't appear to say and they have 3 versions 3/8, 7/16, 1/2?" - 3/8 "Are you running a proportioning valve too?" - No Keep it simple and it will work. -Paul
Mark, Yeah, the tandem pedal set I have and the remote set-up on the 308 both have a 3/8-24 thread on the balance bar, which is where the remote cable connects. The remote is a little disappointing. The cable tends to wind up before the balance bar turns but it's better than stopping to make bias adjustments with wrenches I have no proportioning valve either. I never had one on any race car but they all used tandem master cylinders and I never had any real problems. Bonsai out-braking my opponents into a turn was a favorite tactic of mine so I wasn't exactly babying the brakes. Easy braking on warm-up or cool-down laps was no different though. The idea of installing a prop valve is interesting though and I might experiment with it. After all, I raced on bias-ply slicks and didn't find them objectionable because I didn't know any better. Radial construction came late to race tires.
