Brake upgrade questions

[sparg93]

I might be able to shed some light on this...i have a '99 4dr and did the swap from 1/2t calipers to 3/4t calipers.

http://www.tahoeyukonforum.com/forum/showthread.php?t=19943

Also, 2dr tahoes have 10" drums, 4dr hoes have 11" (i'm not familiar with police packages).

If you only upgrade to the 3/4t calipers w/o hydroboost or master cyclinder upgrade, it's a COMPLETE waste of money; smash on the brakes, you will know what I mean.

Also, you should go with the 3/4t pads IMO. You will need to grind off the inside of the metal bracket attached to the pad b/c it will rub the top hat of the rotors, but it is definitely larger then 1/2t and more friction is always better. If you already purchased 1/2t pads, I would imagine staying with them is fine.

Here is my setup:
Cryo PowerSlot Rotors
3/4t Hawk LTS pads
3/4t AC Delco Calipers
Blue Brake Fluid (name is escaping me)
SS lines

My thoughts:
SS lines are worth dog shit for our applications (as you mentioned earlier). If they tighten up your brake feeling, it's b/c the brake lines needed replacing to begin with. The 3/4t calipers have noticeably larger pistons and 3/4t pads are noticeably larger.

Some folks have upgraded their master cylinders (larger piston/spring) and they commented it tightened things up dramatically, but caused SIGNIFICANT effort when smashing the brakes (not as safe). There are a few cases where folks upgrading to the hyrdo setup and they fell in love their system afterwards.

A full hrydo setup when done by yourself is about $700...a few writesup are on here.

IMO, a hydro setup would have a significant benefit over rear disc conversions. Rear brakes are doing very little stopping compared to the discs up front. When you smash on your brakes, you will notice the brakes aren't even close to locking when you first smash them...i.e. not enough "power" going through the calipers to clamp down on all that mass.

So, if you simply upgrade the rears, I feel you will get very little benefit b/c you're fronts are not exerting enough clamping for as-is. If you hydro the setup and still want more stopping power, then upgrade the rears and I'm guessing you would see a few feet knocked off your stopping distance.

The hyrdo vs. rear conversation is based on research and my opinion. The front conversion advice is from actual work I performed.

I hope this helps!! I'm going to hyrdo my setup this summer and will definitely post all the numbers for everyone to see.

 

[AtomicHoe094]

the disc to drum is more for looks IMO. i hate those ugly ass drums and will take the ease of working on discs alll day long. Thats mainly the reason why i got the SSBC kit, sells for 1300 bucks got it for 300 then i bought slotted rotors for that kit which was 250.

if you want more info check out this thread
http://www.truckinweb.com/tech/0807tr_ssbc_truck_force_10_brake_kit/index.html

 

[sparg93]

nice - i agree, the look of the rear discs is a great improvement over drums!!

 

[AtomicHoe094]

thats probably about it too! haha i still keep the factory Ebrake cable which is still positive as well. The calipers are actually from like earlier fords and such. They say "Varga" on them.

 

[retorq]

Stock Before Lift
Pressure-tested at stock caliper: 900 psi
50-0 mph: 90 ft.

After Lift
Pressure-tested at stock caliper: 900 psi
50-0 mph: 138 ft.

After Installation Of SSBC Truck Force 10, Two-Piston Front Brake Kit
Pressure tested at caliper: 800 psi
50-0 mph: 128 feet

After Installing Hydroboost
Pressure tested at stock caliper: 1,200 psi
50-0 mph: 98 ft.

Umm WHAT?! After a two piston caliper and more pressure you need almost 10 feet more room to stop then you did stock?!

 

[2K6TBSS]

Umm WHAT?! After a two piston caliper and more pressure you need almost 10 feet more room to stop then you did stock?!

The way I am reading this is the final stopping distance is lifted, with 2 piston calipers, and hydroboost. It looks to me like the stopping distance was better my almost 40 feet.

I would have liked to see what the stock stopping would have been with the 2 piston and hydroboost.

 

[sparg93]

Yeah, i read it the same way...hydro boost knocked of 30ft.

Very cool that he measured PSI at the caliper, it completely makes sense!! Smash on your brakes @ 50mph (stock config) and it feels like there isn't enough pressure grabbing the discs...add hydra and the extra hydrualic push on the calipers increases their grabbing strength.

---------- Post added at 01:00 PM ---------- Previous post was at 12:59 PM ----------

Retorq - where did you grab that data from? Which member posted it?

---------- Post added at 01:05 PM ---------- Previous post was at 01:00 PM ----------

I would bet money that when I upgraded to the 3/4t calipers my pressure at the disc decreased too b/c I didn't upgrade the master cylinder or go hyrdo.

With the two piston design mentioned above (prior to hydro), PSI dropped from 900psi (stock) to 800psi (two-piston). I would imagine the cummulative piston size is larger with the two-piston then the 1/2t (stock) caliper....larger pistons take more hydraulic fluid to close them.

Do my thoughts make sense or is there something else at work here?

 

[steamroller]

I would bet money that when I upgraded to the 3/4t calipers my pressure at the disc decreased too b/c I didn't upgrade the master cylinder or go hyrdo.

With the two piston design mentioned above (prior to hydro), PSI dropped from 900psi (stock) to 800psi (two-piston). I would imagine the cummulative piston size is larger with the two-piston then the 1/2t (stock) caliper....larger pistons take more hydraulic fluid to close them.

And even though pressure at the caliper dropped the stopping distance was 10 feet shorter.

So, the big measurements will be:
1) Stock
2) 3/4t calipers & 3/4 pads
3) 3/4t calipers & 3/4 pads & stainless steel lines

Subjective statement:
The pedal has firmed up a little bit at the top. The big difference I've felt is after the first few inches of pedal travel the truck stops faster...you can feel the calipers/pads grabbing harder then stock.

In your thread when you first switched you said there was a difference and now you are saying there isn't. Which is it??

 

[sparg93]

And even though pressure at the caliper dropped the stopping distance was 10 feet shorter.

The piston on the 3/4t is larger so I believe the same overall force is being applied...just to a larger area, effectively decreasing the PSI. That would be my guess...any ideas? Maybe b/c it was only 100psi the braking distance decreased...but at like 600psi, the braking distance would increase. If we could vary the psi, it would be a fun experiment!

In your thread when you first switched you said there was a difference and now you are saying there isn't. Which is it??

Yes, at speeds around 30 - 40mph the above statement is still true; rig seems to stop faster (never measured though). I should have done more testing before I made the statement you quoted, but with the horrible weather, it wasn't practical to "test" them out.

On my updated statement - I noticed the weekness when i smashed on the brakes doing 60mph (first time about a week or two ago). It feels as though the calipers aren't strong enough to slow the disc down and they're not grabbing hard enough. Now, we all know 3/4t calipers are powerful enough, but I don't think I'M exerting enough force fast enough through the pedal to get these monsters to clamp down...I think any normal person would have this issue b/c of the extra hydraulic fluid that needs to move through the system.

With that in mind, I started to more seriously investigate the hydro systems and it started to make more sense. As an example, if you were to slap 1t calipers and not hydro your brake system, your foot would literally hit the floor pushing the extra hydraulic fluid from your stock master cylinder to the larger piston.

Anyone more familiar with brakes than me that can comment??

 

[steamroller]

Where did the 600 psi figure come from? Wouldn't 2 54 mm pistons effectively reduce the pressure more than the bigger than stock single 80mm piston? Maybe I'm not thinking about it the right way.

Just to clear up the confusion I'm not saying that a bigger piston caliper will get you stop on a dime brakes in a 5500+ lb vehicle. Yes hydroboost will net a bigger gain at a much bigger cost. I don't consider replacing 2 rusty/used/abused calipers that are 12-15 years old a waste of money for what they cost....mine were under $75....don't know what you paid. The stainless lines cost me more than that and did absolutely nothing.

Have you tried pulling the ABS fuse yet?