An idea I had for the brakes

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will e
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An idea I had for the brakes

Post by will e » Tue Dec 28, 2021 4:06 pm

Posted in the Offroad section of this forum.

A few times while wheeling I have had situations where the engine wasn't available and I was on a hill. One time I lost oil pressure and turned it off myself and had to back down a pretty steep grade. Another time the fuel pump gave out at a very inconvenient time. The thing with vacuum assist brakes is you get one more pump (maybe two) and then it's done. With no vacuum assist the brakes are very stiff and not so good, even worse with all of the weight I have added to my rig.

So, I got the idea to add a vacuum pump to the brake system. It's a popular modification for over cammed street cars with low vacuum. They use the pump to provide enough vacuum for decent power assist in normal driving.

Normally I have enough vacuum but on those rare situations where I am on a hill and the engine isn't cooperating or I am being drug out of a trail for some other reason I didn't have the advantage of vacuum assist.

I started with a vacuum canister, that got me a couple more brake pumps. Later I added a vacuum pump to the system. My vacuum setup is a bit different compared to what the manufactures show in their installation manuals. They normally show the pump between the engine vacuum and the tank with a check valve between the engine and the pump. I found the inline check valve was really restrictive and limited how well the normal engine vacuum worked so I put the pump between the tank and the booster. This works great. The tank has its own check valve so when I turn on the pump it creates vacuum in the booster and the tank.

Currently it's wired with a manual switch to work even if the ignition is off. This means it will operate while normally parked and the ignition in the 'off' position. This could drain the battery if I forget to turn it off. I am thinking of changing so it only operates if the ignition is in the 'on' position.
I normally leave it turned off and will just turn it on if I am approaching a big hill or have had an engine problem.

What do you all think of this idea? I haven't seen it used much for offroading. Any thoughts on alternatives to how I installed it?

Image
Last edited by will e on Thu Dec 30, 2021 6:44 pm, edited 1 time in total.
81 Waggy 'WILL E' Retired
82 Cherokee WT - SOA/SF/high steer/Alcan springs/agr box/Borgeson steering shaft/AMC 401/performer/holley TA/HEI/BeCool/727/ALTAS (2.0/2.72/5.44)/D60 Snofighter(Yukon Zip,hubs,stubs,4.56)/14 Bolt (FF,BF shave, Discs, ARB,Artec Truss)/MTR 37X12.5/Corbeau XRS Baja & 5 point retractable harness/Hella Aux lights/tuffy console/killer32 sliders/Evil Twin bumpers, rack and roll cage/WARN 8000/TT Fabworks steering brace/dual batts/custom TC skid plate/ARB fridge

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Stuka
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Re: An idea I had for the brakes

Post by Stuka » Tue Dec 28, 2021 4:23 pm

I think thats a great idea. Not having power assist to hold a heavy vehicle with big tires can really suck. Almost all newer vehicles use vacuum pumps for the brakes since most new vehicles are turbo charged. So you really only get vacuum at idle. The difference is they are often mechanically driven. But some are electric.
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SJTD
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Re: An idea I had for the brakes

Post by SJTD » Wed Dec 29, 2021 9:49 am

My Nissan motor had it mounted on the back of the alternator.
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letank
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Re: An idea I had for the brakes

Post by letank » Wed Dec 29, 2021 4:25 pm

Very good idea, diesel cars had electrical vacuum pump -but, I only worked on a Peugeot years ago, ah, ah, a 1/4 century ago-

Yes, it is really chilling, the engine dies on a cold morning and you are barreling down a steep SF hill... put shifter in neutral while stomping on the brake pedal and turning the ignition switch while pumping for gas to dump gas down the carb throat.

Can you share any refs on the vacuum pump and the vacuum canister?

Thank you for such a very useful idea
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SJTD
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Re: An idea I had for the brakes

Post by SJTD » Thu Dec 30, 2021 1:07 pm

25 Years? That's when I started my project. One reason I've got shuch an archaic motor.

I've gone to hydroboost but that too gives you nuttin if the engine's off.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.

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Pablo
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Re: An idea I had for the brakes

Post by Pablo » Tue Apr 12, 2022 9:39 am

SJTD wrote:
Thu Dec 30, 2021 1:07 pm
25 Years? That's when I started my project. One reason I've got shuch an archaic motor.

I've gone to hydroboost but that too gives you nuttin if the engine's off.
It feels like my project is taking me 25 years, but only 8 so far. :banghead:

To the main topic, maybe a good reason for a line lock? If your power goes out, pump the brake and throw the line lock to lock at least half the brakes on?
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Yeller
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Re: An idea I had for the brakes

Post by Yeller » Tue Apr 12, 2022 10:30 am

I can get 3 good solid pumps out of my hydro boost. After that you still have brakes but may need to source your in inner green Hulk to have much power. You have the same issue with a vacuum booster unless you have an electric vacuum pump. Even that is limited to battery power.
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Topic author
will e
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Re: An idea I had for the brakes

Post by will e » Tue Apr 12, 2022 3:55 pm

The line lock is a good idea but the main reason I installed the vacuum pump is if I lose engine power while wheeling. I remember one time I was climbing a pretty steep hill out by box canyon. My oil pressure dropped so I killed the engine and had to back down with no power brakes.
81 Waggy 'WILL E' Retired
82 Cherokee WT - SOA/SF/high steer/Alcan springs/agr box/Borgeson steering shaft/AMC 401/performer/holley TA/HEI/BeCool/727/ALTAS (2.0/2.72/5.44)/D60 Snofighter(Yukon Zip,hubs,stubs,4.56)/14 Bolt (FF,BF shave, Discs, ARB,Artec Truss)/MTR 37X12.5/Corbeau XRS Baja & 5 point retractable harness/Hella Aux lights/tuffy console/killer32 sliders/Evil Twin bumpers, rack and roll cage/WARN 8000/TT Fabworks steering brace/dual batts/custom TC skid plate/ARB fridge

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devildog80
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Re: An idea I had for the brakes

Post by devildog80 » Sun Apr 24, 2022 3:24 pm

That sounds like a lifesaver idea for sure.

As I am just starting rebuild on my '84 Grand Wagoneer, will keep that in mind after getting it back to normal, and considering worthwhile mods to think about.
'81 CJ5 Base, 258 I6, MC2100, T176 4 spd, 300 TC, D30 Front NT, 3.31, 2-Piece AMC 20 rear NT, 3.31, 4" high arc spring lift
'84 Grand Wagoneer, 401 V8 (.030 over), MC2150 HA Comp, 727 auto, Selec-trac NP229, AMC 20 REAR - D44 FRONT - WT 3.31, 4" high arc spring lift
Rather be driving, than waiting to be modified


michaelbennett902
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Re: An idea I had for the brakes

Post by michaelbennett902 » Fri Jun 24, 2022 10:53 am

Thanks for sharing


j10builder
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Re: An idea I had for the brakes

Post by j10builder » Sat Jun 25, 2022 5:36 pm

I really like this. Thanks

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