Kredz28

Did the ls1 brake upgrade, but my larger cam isnt making enough vacuum. The car stops like ***. I can only push the pedal in half way...feels like real bad fade. I know I need a vacuum booster, but I need some help in this area.

Kredz28

ttt

Kredz28

So nobody in the Fbody Community has ever had a cam with LS1 brakes???

Kredz28

I put the ls1 brakes on and have a large cam. Im only pulling 11 hg of vacuum and I dont have enough vacuum to stop in a hurry. Braking is horrible since upgrading to ls1 brakes. Anyone have a remedy?

dangalla

like i posted in your other thread on the same subject you prolly just need to bleed the brakes or possibly have them bled by the dealer due to the abs unit

and how big is your big cam cause it sure cant be the medium cam in your sig, that wont cause any problems with braking

JakeRobb

Does the pedal go to the floor and you're still not stopping fast enough, or is pedal travel normal, but it's just hard to press the pedal?

Door #1 means bleed the brakes. Door #2 means vacuum.

greenmachinedriver

breaking should be better with the ls1 brakes. are you shure you bled the system properly?

Kredz28

I cant push the pedal in all the way! Feels likes theres a brick between the pedal and the floor. Im pretty sure I bled the brakes properly, but im assuming that with my large camshaft and ported heads im going to be needing a little "boost." The 2 piston calipers from the ls1 likely need more vacuum than the stock single piston lt1 design.

What are my options to get more vacuum?

Kredz28

cam specs are 224 intake, 236 exhaust with 535" lift on the intake and 555" lift on exhaust w/ comp pro magnums (1.6)...heads are ported lt1's, flowing 290 intake, 210 exhaust...on the boost guage, I only see 11-13 hg of vacuum and from what Ive read I need more like 17 hg to get optimal braking.

I dont know if this makes a difference but its got a Moser 9" and I dont have ABS anymore...

JakeRobb

I don't know about getting more vacuum, but I do know that GM has used a couple of different brake booster systems that didn't require vacuum to operate.

PowerMaster
Used on turbo Buicks. This system uses an electric motor to generate and maintain pressure in a small reservoir, which is then used to provide braking power. A plus -- after the engine is shut off, the reservoir usually contains enough pressure to provide power-assisted braking for 3-4 pumps of the pedal.

HydraBoost
Used on lots of trucks, Astro vans, and several other vehicles. This system uses hydraulic pressure from the power steering pump to power the brakes.

FWIW, I've heard of a lot of Grand National guys converting from PowerMaster to HydraBoost, but I've never heard of anyone that has gone the other way. The PowerMaster system on my GN works quite well, especially since I replaced the reservoir with a dealer replacement part (GM increased the size and pressure handling ability of the reservoir sometime after my car was built).

Injuneer

No need for two threads on the same subject.

Merging......

95Bluestreak

Cam specs at 236/242 and I installed a comp cams vacuum canister and all my troubles are gone.

Jason

Kredz28

Ok...What about the install? Does the pump come with everything you need or instructions? Whats the part number?

mzgp5x

I had a problem with brakes after adding a Procharger D1 and large cam (231/ 240* @ 0.050"). It also stopped like "azz" (Ha). I had 3" Hg @ idle and 13" Hg @ cruz. Not enough. Pedal was real hard @ idle when you have low vac in the booster. The booster unloads when you let up on the brake pedal. You need @ least 16". So... I went to Summit and ordered a SSBC Vac pump (a $280 value!). Did the job, but had to mount it in the rear due to lack of space. That's what happens when you mod. I'm not moding back to stock. Hope this helps. b>

95Bluestreak

No pump, just a can. I bolted the vacuum can under the LH fender below the brace for the cai's. All you have to do is drill two holes and bolt it down; then run a feed line from the intake to the can then a line from the can to the brake booster.

Jason