Pump for Hydroboost? (1 Viewer)

[SuperBuickGuy]

I race cars.... glazing happens a lot, especially when you're a novice.

Vacuum canisters give you a good 2nd stroke on the pedal with assist (at idle).

that 25% more on the rear concerns me - time to add a proportioning valve. Even in its "open" position, it reduces flow by 33%, so that would get you into the ballpark for fine adjustment.

If you don't turn the rotors, then remember to hit the rotor with a bit of sand paper to knock the glaze off.
And - do follow the manufacturer's break-in procedure religiously. If you do, you will be astounded at how hard you can brake.

 

[srgould41]

I have a prop valve. It is dialed to the max. When I first started driving with the disc brakes it stopped very nicely. When I started dialing in the prop valve I discovered that the rear was doing all the work. My plan now is to install smaller calipers in the back and, with luck, larger calipers in front. I am ordering a GM caliper tonight to test fit to see if I can fab a bracket for it and use the stock front caliper ears to mount off of. This caliper, if I can make it fit, has 39% more surface area than the 4Runner ones I am running now. The pads have more surface area too. If I can't make it fit then it's on to hydroboost to get more line pressure. I want to avoid adding more complicated systems if I can. Plus these calipers are way cheaper then adding hydroboost.

 

[SuperBuickGuy]

the other option is to use varying pad types. Long-lasting pads are not as aggressive as cheap pads. On my 83 Chevy truck, I used pads that cost $10/set for the front and $50/set for the back.... it was perfect.

another way to do this is to increase the line size in the back (more volume, less pressure).

and in that vein, make sure your line sizes match and that you're in the right port for front/rear. On disk/drum vehicles, the fronts get 60% of the volume, rear 40%.

and finally, larger pads don't, necessarily, mean better braking - a pad's ability to stop is based surface area, pressure, and chemistry of the pad. I had a friend with a 66 chevelle that he put large by huge brakes on (IIRC 14") and it stopped better when it was all drum. We ended up getting a more aggressive pad to bandaid his issues - but in the end, it stopped marginally better than the disk/drum 70 Skylark I had. The problem with soft (aggressive) pads is they're far more subject to heat fade and glazing - thus it'd work fine for street driving, but he had to change pads to the aggressive-must-be-hot ceramic pads for autocross... and I'm still not sure he was faster.... the upgrade that cost a Miata, but made the car slower... such is the paradox

 

[srgould41]

I agree that all the changes we make have trade offs. I actually did try different pads. The pads in front are a more aggressive compound while the rear pads are a harder compound. I have been reading and studying braking for the past five years or so. There are lots of differing opinions and opposing science even. For example there are sites that also state larger line size will decrease line pressure and yet others that refute it. I even read calculations used to determine parasitic loss in varying line sizes and materials.

I am with your friend, when I had all 4 drums perfectly adjusted on a warm and dry day they stopped better than the discs hands down. When wet they didn't do much. I could be stopped facing up hill and with two feet on the brake pedal I would still creep backwards.

I have learned a ton and have tried many things. I have made lots of positive steps from where I started at, but I am not where I want to be yet. I do know that the normal 4 wheel disk mod is not a good one. It would be great if some FJ40 driver worked at a junk yard and could go around to each car and measure the brake specs. I am sure there are better options to the typical Monte Carlo rear calipers that won't cost a fortune to install.

I have disc/disc masters. Three of them to be exact. I made sure to go that route when sourcing them. My current one is 7/8" from a Toyota MR2. The other two are listed as Corvette masters, 1" and 15/16". I will be going back to the 1" with either larger front calipers or Hydroboost. I might even have to move up to 1 1/8" for HB according to the companies that sell kits. Time will tell.

the other option is to use varying pad types. Long-lasting pads are not as aggressive as cheap pads. On my 83 Chevy truck, I used pads that cost $10/set for the front and $50/set for the back.... it was perfect.

another way to do this is to increase the line size in the back (more volume, less pressure).

and in that vein, make sure your line sizes match and that you're in the right port for front/rear. On disk/drum vehicles, the fronts get 60% of the volume, rear 40%.

and finally, larger pads don't, necessarily, mean better braking - a pad's ability to stop is based surface area, pressure, and chemistry of the pad. I had a friend with a 66 chevelle that he put large by huge brakes on (IIRC 14") and it stopped better when it was all drum. We ended up getting a more aggressive pad to bandaid his issues - but in the end, it stopped marginally better than the disk/drum 70 Skylark I had. The problem with soft (aggressive) pads is they're far more subject to heat fade and glazing - thus it'd work fine for street driving, but he had to change pads to the aggressive-must-be-hot ceramic pads for autocross... and I'm still not sure he was faster.... the upgrade that cost a Miata, but made the car slower... such is the paradox

 

[SuperBuickGuy]

you mention the monte carlo rear caliper (I'm presuming you got the Firebird/Cadillac/etc combination e-brake/caliper - otherwise ignore the rest of this). I really don't like those - I say this a lot to my dad (who is master at trying to do it) that something that does everything does nothing well. You probably know this, but those calipers have a screw in the middle that is supposed to turn to apply the parking brake, it also has a catch that adjusts the brake as well. The issues, and there are a bunch, come from that design. The screw sometimes doesn't work, or doesn't allow the pads to release, or works intermittently and on and on. This is the reason why I'm making a transfer-case brake instead of using those calipers on my build. Your next step - buy monte carlo, non-e-brake calipers and try your system. Did your system (can't remember, too lazy to look back) have a residual valve installed? does it still have the stock proportioning valve?

 

[Mace]

Glad you are listening and reading to ferret out the poor information from valid info! The "standard" rear disk brake conversion is not a great one. It works, but it is unbalanced. One of these days, someone will get it ironed out tho!

Monte Carlo are not Eldorado calipers. MC does not have the emergency brake.

 

[SuperBuickGuy]

Cadillac Seville, and Firebird also used an e-brake caliper. IROC Camaros, after 1986 had a better design, but it was still problem-plagued and never better than the separate drum-e-brake/disk brake caliper (not to mention the Ford 9" disk-brake/ebrake caliper that came on the Versaille, or the 8.8 DB/eB that came on early fox-body mustangs).

as for sorting it out, it's so model specific that the hot-rodder needs to figure it out themselves- no one is going to do the work for you; it simply doesn't pay. Which is why I'm answering long-form rather then short form and including links to places to calculate.

With that said, the good reason to use the more common set-ups is that someone out there has probably suffered the same issues as you and when your equipment is the same as theirs - it makes it easier to find solutions.

 

[srgould41]

Mace is correct. The Monte Carlo (front) calipers do not have an internal p-brake. Props to the guys who originally figured out the easy Chevy truck rotor/metric caliper combo. It is not ideal, but is cheap and works OK for many people. Trying to get old rebuilt p-brake calipers to work and work well (especially with the p-brake being used) is not easy. I have read posts about attempts being made, but I am not sure I ever read of a success.

The T-case p-brakes are nearly worthless in my opinion (and others). I have rebuilt mine three times and never got it to work well enough to keep the truck from rolling on anything but flat ground. Last Saturday I ended up driving a few miles with it set. It works so well you don't even know when it's on. I suspect that caused the pads to bed in well, though. Yesterday I tightened the adjuster then parked on a hill (my driveway) with just the p-brake set and the trans in neutral it actually held for the very first time ever.

 

[srgould41]

Cadillac Seville, and Firebird also used an e-brake caliper. IROC Camaros, after 1986 had a better design, but it was still problem-plagued and never better than the separate drum-e-brake/disk brake caliper (not to mention the Ford 9" disk-brake/ebrake caliper that came on the Versaille, or the 8.8 DB/eB that came on early fox-body mustangs).

I liked the firebird calipers as the piston diameter is nearly perfect to match the 4Runner fronts. I was researching them until I learned they are for thinner rotors that I have.

as for sorting it out, it's so model specific that the hot-rodder needs to figure it out themselves- no one is going to do the work for you; it simply doesn't pay. Which is why I'm answering long-form rather then short form and including links to places to calculate.

With that said, the good reason to use the more common set-ups is that someone out there has probably suffered the same issues as you and when your equipment is the same as theirs - it makes it easier to find solutions.

That is why I read and post. Looking for ideas to make things better for myself and others. I especially appreciate good intelligent replies like yours. There are some solutions available to get great brakes, but with a cost that is commensurate.

 

[SuperBuickGuy]

oh goodness

the biggest issue with answering someone's questions is always there's someone out there who wants to shut it down by attacking side points rather then answer the problem at hand - to wit (and excluding for a moment that I said "if it's not an e-brake caliper, ignore this")

Monte Carlos, in the 80s, had the same frame as the 76-79 Seville. They had the same rear end, except for brackets, as the 2nd gen Camaros, and the rear differential as, well, pretty much any rwd GM car of that era. To be completely technical, the caliper you have is called the P-metric or metric caliper. I wouldn't, actually, ever say Monte Carlos came with or didn't come with disk brake rears because GM was really good at making one-off cars for promotions - thus, like the SS Monte Carlo, it may have had rear disk brakes in some special, COPO order from GM. The point is parts were in the shelf for the clever ordering person.

P-metric calipers are still used in "late-model" class dirt-track racers and you can buy them from any of the suppliers who made their name in selling stock-car parts and are dirt, dirt cheap. They're simple, reliable and cheap.

I've had all manner of e-brake set ups and the one that works best for me is the transfer case one - I admit, though, I'd thought about simply doing a hill-holder and may still.

Anyway, as I said long ago - once you get past that list of 10, it's all speculation and I'd have to see it in person to give any other advice.

 

[srgould41]

All I have had to go on was speculation and the trial and error approach. It has been fun to do, not overly expensive, and a great learning experience.

 

[SuperBuickGuy]

It's how I learned - when I started, all I had were the "it's impossibles" and the "told you so's"

which is probably why I have such little patience for them now.

 

[Mace]

SR, give the hydroboost a try to see if you like it. At this point, it's about your easiest option. You've certainly covered your bases well on everything else.
Standard sag canned ham pump will work fine.
The issues with the MC calipers is why I left my fj60's rear brakes alone

Course, you could get a 79 or later 40 housing (or 70 series housing) for the better drum brakes (with e brake included)

 

[srgould41]

Thanks for all the replies. I had this hair brained idea I could source a larger piston caliper for the front. I found an awesome single piston caliper with 2.81" diameter. It would have provided 40% greater clamping force. I picked up a pair and test fitted one. Not even close. Even if I cut off the rear turn stops it would not clear the birf housing. Oh well, it was a nice idea. They were brand new too!

Reverting to hydroboost. I just ordered all the brake hard and soft line items (going with AN hoses). Next paycheck will be new Wilwood 2" metric rear calipers and the paycheck after that the HB hoses and fittings.

I noticed when pulling my current rear calipers that the mount holes are very oblong. I suspect they were that way from Auto Zone. I bet the rebuilders don't even bother with fixing worn mount holes.

 

[SSCR]

Anyone ever look at Tallon Hydraulics for their hydro booster units?

 

[Gumby]

I looked at Aurora pick and pull for mine.

 

[srgould41]

Tallon was fast to answer questions about the fittings I needed. I didn't end up buying anything from them. I got my booster from eBay just because it was easier for me.

My systems is now in and working great.

I looked at Aurora pick and pull for mine.

 

[SuperBuickGuy]

good news, how did you run your return line?

 

[srgould41]

I use a brass hose "T" with the HB return using the straight section of the T.

good news, how did you run your return line?

 

[SuperBuickGuy]

I tried that once, when on the brakes and turning the steering would shimmy and the brakes pulse.... I presume you're not having those issues?