[kdubaz]

Ok all, here it is, my FAQ about hydraulics. Before I go off on everything, I'm going to give you some background about my knowledge of hydraulics to let you know where I'm coming from.

First off, my name is Kevin Whipps, and I'm a freelance writer & photographer for Street Trucks, Import Racer, Edge, Lowrider, and a bunch of other mags. A year or so ago I published an article in Lowrider called, "Accumulators 101" which was all about accumulators and their role in hydraulics. More recently there was an article in Lowrider called "The Protector" about a pressure relief valve for hydraulics. The Jan '04 Issue of Street Trucks has my Sierra in it with a full install of the hydraulics from start to finish.

Beginning in 1996, I juiced my first car, my 1996 Honda Civic that was destined to become the "Bad Apple." That car was on the cover of the premier issue of Import Racer, as well as on the March 2000 issue of Lowrider Euro. The car went through at least 10 different hydraulic setups, from a simple 2/4, to a 1/8 with manually plumbed dumps, to a 4 pumps setup, and was truly a learning experience for me and hydraulics.

A year or two ago I had an orange Focus wagon named "Makin Waves." The wagon had 4 pumps on it, 3 batteries, and rode great. It was on the cover of Lowrider Euro and made me the only person to make the cover of Euro twice.

I also have done lots of hydraulic installs. When I say lots, I'd say easily over 50, probably closer to 100. Everything from minor touch ups to start to finish rides. I've laid a Camry out on the ground so it drags, I've gotten S10's to do mad 3-wheels, and I've gotten a Civic to do a 9" front STANDING 3 wheel.

In this FAQ I'm going to make one thing clear; Hydraulics aren't perfect. Then again, neither are bags. This faq is designed to clear up some of the misconceptions about hydraulics, as well as educate the masses.

If you're reading this first post and there aren't posts after it, please do not post until I've finished. I'll be sure to makeit when a note of it when I'm done.

Also most of this faq is straight off another site, but there are some new updates that I made for clarification.

 

[kdubaz]

Pumps & Dumps

Let's start with the foundation of a good hydraulic setup, the pumps.

A pump is exactly what you think it is. It pumps fluid from one place to another. Real simple really. You can equate it to a compressor in an airbag setup if it makes it clearer to understand. Here's how the pump works.

On one end of the pump is a 12 volt motor. That motor has a splined end on it, and the motor bolts to what is called the block. The block is a 6X6X1 piece of aluminum that is milled to accept fittings and so on.

At the other end of the block is the gear. The gear has a splined end on it also. The two splined ends, one from the motor and one from the gear, are connected by what's called a key. This key can come in many different spline patterns so that you can change motors without having to change gears.

Surrounding the gear is a tank. The tank itself is a reservoir for hydraulic fluid. It serves to provide fluid to the gear when the gear turns, as well as to catch the returned fluid when it is expelled from the system.

So how does it work? If you give the motor 12v of power, it turns the splined end. That splined end turns the key, which turns the gear. The gear itself has two gears inside of it which suck the fluid from the tank into the gear, and pulls it through passageways in the block, out to the port at the top known as the "press" or pressure fitting.

Dumps

After the pressure fitting, there has to be a way to divert where the fluid goes. In an airbag system, they're known as valves. Hydraulic systems have valves too, they're called Dump Valves, or dumps for short. On the inside, a dump is shaped like a "T". Fluid can pass through the top of the "T" all day long without any problems. The bottom of the "T" is controlled by the valve itself. When power is given to the dump, the stem of the dump opens, which releases pressure and allows the fluid through the bottom of the "T'. The fluid then goes through a hose called a return line, and then into a slow down valve. All a slow down valve does is control the flow of fluid to the tank. It's a needle valve, so you turn a screw to speed up or slow down the fluid. Since the truck is dropping only as fast as the fluid can move, the slow down is essential to keep the truck from "gravity dropping." The slow down is the ported into the block, which dumps the fluid back into the tank, recycling the fluid and resetting things to normal. The slowdown gives hydraulics a distinct advantage over airbags, as you can now control how your truck drops, even how fast each corner drops, depending on how your slowdowns are installed. I've seen plenty of bag setups that drop by gravity, and that can't be good.

There is one other piece that goes between the press and the dump, and that's the check valve. Just like any other check valve, it keeps fluid moving one direction, and doesn't allow it to go back. Hydraulics work on pressure, and the check valve allows the pump to build up pressure. Without it, the truck would fall right back down once the truck had been lifted.

 

[kdubaz]

Cylinders

So now you know where the fluid comes from, and how to divert it, now you need to know where it goes. In this case, it goes to the cylinders.

Cylinders go by a lot of different names; lifts, rams, etc. Whatever you call it, they're all the same basic design. It's a piston that is encased in a piece of round tubing. At the top of the tubing is a port for a fitting. At the bottom is a threaded collar that holds the casing together, and keeps fluid inside.

The piston inside the cylinder looks just like the piston in your motor. Instead of piston rings though, you have rubber seals to hold in the pressure. There can be any number of seals, but there is usually at least 2 pairs, and Pro-Hopper competition cylinders have 6 total seals. The seals are in pairs, with one rubber seal to one teflon seal. The teflon seal is to keep the rubber seal in line, as well as to clean the inside of the casing.

The piston top is wider than the ram itself, so a bushing is placed at the bottom of the ram. That piston sits just inside of the cylinder casing, right at the base with the collar. It is usually made out of brass, but some cheaper bushings are made out of plastic. It keeps the ram in place along the bottom of the cylinder, and catches any excess fluid that may have passed the seals.

The ram has a threaded port at the bottom of it. That allows it to be bolted to anything you want. Most common in truck installs are heims joints. A Heims joint is an eyelet like you would find on an FBI 4-link. Other common mounts are powerballs. A powerball is a pivot that is encased in a small cylinder. You can weld it to whatever you want, and it gives the cylinder maximum articulation. You can also put a cup at the bottom of the ram. That cup is designed to fit inside of a coil spring. You'll see that the most in hoppers, but you can use them if you don't want to hop but want a smooth ride. Just relocate your shocks like you would with a bag setup and you'll be good to go -- but more on that later.

We'll also discuss seal changes later in the FAQ also.

 

[kdubaz]

Batteries

Every hydraulic setup has batteries. Some lighter trucks can actually run 1 battery -- even just the stock battery, while others want to run 12 batteries for more power. I usually won't run anything less that 2 batteries, but it depends on the install.

Here's how it works. Let's say you have 2 batteries. You wire them so that you have a crossover from + to - . (I believe that's called Series, but it could be parallel, I always confuse the two.) If you have more batteries, you do the same thing until you're done. What that leaves you with is a negative post that's free at one end of the system, and at the other, a positive post. The end result is that you multiply the number of batteries you have by 12volts, and you get the total voltage that the last positive post will read. If you have 4 batteries, that means you'll have 48 volts.

Without getting too complex, the more voltage you have, the faster your setup will be. Also a pump will not be able to lift a big block V8 on 12 volts alone. The more voltage, the more power the pumps run. This is why you see heavier cars running more voltage. My Civic had 2 batteries in it and hopped up. My Sierra had 4 batteries, and moved pretty good, but not as fast as the Civic.

The negative post now needs to be grounded to keep power moving. Basic DC electricity tells you that power runs from negative to positive, so it has to be grounded for the pumps to get power. You COULD run the ground directly to the frame with a bolt, but that's not safe. We'll get into why later, but I like to run a welding twist-on connector underneath the front of my seat. I run 2/0 welding cable from the back battery all the way to the front of the truck. This gives me a quick disconnect to the system should anything go wrong, or should I want to disconnect power to the hydraulics when I park, or for security or whatever. I then bolt the other end to a seat bolt.

Another note here: The number of batteries that you run also depends on the amount of pumps that you have. The more pumps, the less work each motor has to do, so the less battery power you need -- to a point. The problem is, you really need more batteries now, so that you can go longer between charges. It ends up being a guesstimate based on weight, which really isn't that difficult to figure out. Most of the time you're looking at between 3-6 batts, depending on the weight of the truck. Of course I've seen 2-pump duallies running 3 batts, so it can be done, but it's slow.

 

[kdubaz]

Solenoids

You have batteries to provide power, and you have pumps that need power, so you need a way to get power from one to the other. You couldn't just wire it straight through though, because then the pump would constantly be on. A solenoid is how you do it.

A solenoid is a switch, plain and simple. You have power coming into it, and a wire that activates it at the other end. You hit a switch which provides power to the solenoid. That solenoid then activates, and opens the power so that it can flow from the batteries to the pump.

Solenoids are probably the weakest link in the hydraulic chain, but they have gotten better. A solenoid is just like a pump in that it runs on 12 volts. With more voltage going to it, a solenoid can burn out. As a result, its very common to see rows of solenoids in series to compensate. The problem happens with a solenoid sticks. It can either stick open or closed, but either way isn't good. When it sticks open, so that the pump keeps running, it's called a runaway.

Prestolite recently came out with a solenoid block that I now use in every install. Essentially they're just 3 24volt solenoids in one case, but they work well. You can run up to 6 batteries off of one block, and they do not wear out anywhere near as fast as your standard solenoid.

So you're wondering what to do with a runaway? Pull the ground. That's why you always have a ground strap ready to go at any time. It's like if your compressor just kept running, it'd eventually burst your tanks. If a pump keeps running, since it's pushing 5000psi+, it can burst hoses, break pumpheads, and all sorts of things. Have a quick release for your ground and you're good.

 

[kdubaz]

Lines or Hoses

After the fluid from the pump exits the dump, it needs to have a way to travel from the dump to the cylinder. That's the hose. The average hose, at least one of any decent quality, is a stainless steel hose wrapped in about 1/4" of rubber and it holds around 5000psi. That's right, 5000. The weak point here is the rubber. Rubber lines tend to flex when the fluid is pushed through them, mainly because of the extreme amount of pressure they're going through. If they rub against a sharp piece of metal, they can wear, and then leave the stainless hose exposed. This diminishes the amount of pressure its able to hold, as well as leave it open to more wear. If a hose punctures, you lose pressure, and therefore, are SOL. Call a tow truck.

That's why when running a line, you have to be careful. I like to run my hoses inside of the frame on a FSC. It keeps it safe from dragging on the ground, as well as being well contained from sharp objects. I use zip-ties to hold the line to the frame. They are easy to use, and don't break off like hose clamps with screws. Sounds like its cheesy, but the fact is it works. On a car, I run the hoses through the exhaust tunnel. Hydraulic hosing are heat resistent, at least up to temps that even a header would get to, so you can butt the hose right up to the exhaust and have no worries.

Another alternative to rubber line is hardline. Hardline is a steel or stainless steel line that is bent with a hand bender. I usually run 3/8 .049 hardline. Bending hardline isn't fun, but on the plus side, you can't wear through it.

Hardline does have a downside. You cannot plumb it directly to anything that may pivot or have stress on it. This means you don't want to plumb it directly to a cylinder unless you're POSITIVE the cylinder never moves. Any movement will flex the stiff hardline, and eventually the steel will give and a pinhole leak will form. Leaks are bad. The only other disadvantage is cost. Stainless tubing is usually around $2.50 a foot, and you'll need anywhere from 30-60 feet depending on the complexity of the system, and how much you're hardlining. Plus there's the cost of tools. This is why most systems have rubber hoses -- they come with the kits.

 

[kdubaz]

Switches

You know those cool acrylic switch boxes that everyone has? You got those from us.

Juiceheads have been running switchboxes or switch panels for years. A switch does just that. It switches power from one place to another. The switches that you use with either bags or juice are 3 position momentary switches. In the neutral position, power goes nowhere. Let's call that neutral position position 2 with 1 being up, and 3 being down on the switch. In the 3 position, the power is placed to the solenoid, which allows power to go to the pump. That turns the motor, creates pressure and lifts the truck. In the 1 position, power is given to the dump and that releases the pressure which the system has in it. The weight of the truck then pushes the fluid back the opposite direction, through the dumps, into the return line, then the slow down, and finally the tank.

Switches come in many different sizes, and they're in multiples of 3. There are 3 prong switches, 6 prongs, and 12 prongs. I hear there are 9 prongs, but they're hard as hell to find.

A 3 prong switch is for something simple. Turning on 1 pump and dumping 1 dump. These are usually used for individual switches, like a corner.

A 6 prong switch is used for front, back and sides. The swith turns on as many as 2 pumps and as many as 2 dumps. Remember that a six prong has 2 pairs of 1's, 2's, and 3's as per my example above.

Follow along here and you'll figure out what a 12 prong can do. Usually you use a 12 prong for a pancake switch, a see-saw or something that requires a lot of moves. Pancake means all up or all down, and see-saw lifts the front while dumping the back in one position, then in the other reverses the process.

Switches are fun. You can wire as many as you want. Once I had a friend with a hopping Lincoln Towncar. He came to me with a 4ft wide piece of plexi with some crooked holes plumbed in it. I wired 24 someodd switches into that thing. I personally have a 16 switch panel sitting in my shop waiting to go into the fullsize. Why? Have you ever had a kid ask you how many switches you have? If they've ever heard Dr Dre, they know "16 switches for the bitches in my hood." Much more impressive than having 4 switches, even if you only use 2 of them.

 

[kdubaz]

Suspension

Now you know that hydraulics run on pressure, but what you may not know is that hydraulic fluid is not compressible. That means that it has no give. That equates to a pretty crappy ride.

Old school lowriders, hoppers, and custom guys can run coils. There are lots of different ways to do this, but I'll explain the 2 basic ones.

Coil under

Remember in the cylinder section how I mentioned a cup? Here's how it works;

In the front of your FSC right now there's a coil that mounts between your frame and your lower control arm. What juice guys do is drill a hole in the shock tower, right where the shock stud was, the size of the cylinder. Then the cylinder is slid up through the hole so that the collar catches on the inside of the shock tower. At the bottom of the ram, a cup is mounted. Then the coil is place between the cup and the stock mounting location on the lower control arm.

If you were to do this with a stock coil at stock height, you'd have a lifted truck that lifts even higher. That's why most people run either shorter coils or cut stock coils to compensate. You cut the coil to the height you want, and then you're gravy.

When hopping, the spring then rebounds with the truck, and it gets some major power. The weight of the motor adds to it. If you run a different weight spring you can get higher.

A new school way to do this is to relocate your stock shock off to the side of your lower control arm just like you would with bags. This way you have a cut coil ride, which is better than most other setups.

On my fullsize, I was running accumulators all the way around, but I couldn't get the front where I wanted it. I'm now doing coil under with a 2-ton Pro-Hopper coil, and it rides like a dream.

Coil over

Coil over is just that -- the coil is now over the cylinder.

Since there is a collar at the bottom of the cylinder, that means there's a place for the coil to mount. There's a piece of steel that you can buy called a donut. A donut is essentially a big washer that fits over the cylinder, but not over the collar. It provides a mounting place for the coil. The top of the coil is held in by your upper mount, and that upper mount is in the frame. Most examples of coil over are in the rear. You make a bridge that the cylinder mounts in. The top of the cylinder comes up through a hole, and the coil is in between the cylinder's collar and the frame.

The downside is that the cylinder now moves, and moves a lot. That usually puts metal to metal, which means it will wear the outside of the cylinder against the frame. That rounds out holes, and causes problems with the cylinder ballooning from a weak point. Coil under is neat, but it squeaks, and that's irritating.

Accumulators

Accumulators are godsends.

Since a cylinder is a piston, it can travel up and down inside of the casing however it wants to. In a normal setup though, the pressure keeps it in one place. This is where accumulators come in.

An accumulator is placed in the system after the dump and before the cylinder. What it does is basic. It has a piston inside of it, and a nitrogen charged balloon. When the cylinder is compressed, it pushes the fluid into the accumulator. The accumulator's piston pushes into the balloon, which in turn rebounds. Its essentially a shock absorber for hydraulics.

There are many different types of accumulators, but the most common are the little grenade looking ones.

Your ride is purely based on the ratios between fluid moved, amount of travel, and pressure in the balloon.

 

[kdubaz]

Putting it into practice

I could write forever about the different types of setups, but I'll go basic for you. Each combination of pumps and dumps gives you different movements, and different levels of power.

I'll be explaining them in this style; pump/dumps. Meaning a one pump, eight dump setup will be explained as 1/8.

1 Pump setups

1/1: Best for one corner operations.
1/2: Front, maybe back only setups. Real simple.
1/3: Front & back, nasty sway. Funky setup
1/4 (Manifold): Front, back sides. Hard to find the manifolds though, at least the good ones. Otherwise they're great for individually lifting corners.
1/5: Budget setup. Way funky, but it lets you do everything.
1/8 (manifold): In the late 90's you'd have seen about 30 of these go out of my garage. A 1/8 lets you do EVERY move a 4-pumper will do. Its a manifold. The manifold is a bunch of dumps that are housed in one casing. It allows the fluid to move differently that usual, and is way cool. The manifolds can be problematic though.

2 Pump setups

If you have a FSC, start here. 1 pump isn't going to cut it on a fullsize, even a V6.

2/2: Usually seen as both pumps going to the front.
2/3: 1/1 to the back (T'd off, so you get sway) 1/2 to the front.
2/4: By far the most common setup you'll ever see. It's advertised in all the kits. With a 2/4 you can LIFT front & back, and DUMP sides, corners, front or back.
2/8: One of my old-school favorites. Think 1/8 with another pump. Quick, and it can move just like a 4-pumper

3 Pump setups

3/3: 1/1 to each front corner, 1/1 to the rear, t'd and sways.
3/4: 1/1 to each front corner, 1/2 to the rear. Used for hoppers usually, maybe for 3 wheelin.
3/6: 1/1 to each front corner, 1/4 to the back. That means you can lift corners. For the money, buy another pump and go 4/4.

4 Pump setups

4/4: There really isn't any more simple of a setup. People tend to think it's complicated because of how many pumps there are, but it couldn't be any simpler. One pump per corner, and as many moves as you want.

 

[kdubaz]

Maintenance

Everything needs maintenance, just like a bag setup does. If you don't bleed your tanks for water, if you don't change the seals in your valves, you can have problems.

Seals

There are all sorts of seals in a juice setup, but the two main places you'll find them are in the dumps and the cylinders.

Dumps seals usually need to be replaced once a year, if that. Simply unscrew the dump stem from the body, and replace the seals.

Cylinder seals depend on the setup. If you're running accumulators, you will go through seals faster. When you first get a setup, you'll probably have to change the seals in 3 months. After that, its usually once every 6 months. You'll know when you need to change them when the truck starts to fall.

Fluid

Hydraulic fluid can run low in the reservoir if its not watched. If you have a leak in the system, or something along those lines, fluid can exit the system. Simply fill the tank with the truck dumped and all pressure out of the system.

Batteries

Batteries need to be charged or kept charged. It depends on use, the amount of batteries and so on, but I usually charge my 2/4 4 battery FSC once every 2-3 weeks. On my 4 pump 3 batt Focus I charged it once a month, and even went 2 months without charging it once. With a good automatic charger, you can leave it overnite. Its really no big deal.

An alternative to charging batteries is the Street Charger. A street charger works off your stock alternator to keep your batteries at a constant level at all times. Good for people who don't like to maintain things, they also make sure you're always ready to hit switches.

Lines

If you're running hardlines, you really don't have to look at your lines, but with softlines, check for wear. If you find wear, what I like to do is to wrap a piece of larger rubber hose around the line and zip tie it on, then fix the area where it wears. If it gets much worse, then you want to replace the line, or reroute it.

Solenoids

Remember I mentioned how I kept a quick-disconnect up front on my car? Remember how I mentioned that solenoids can stick? It should all be falling together for you now. If you get really switch happy, the solenoids can heat up and stick open. This is called a runaway, as the pumps just stay on. If you disconnect power, it stops the system. That's why I keep that disconnect handy.

 

[kdubaz]

Re: Maintenance

Q: My friend's '78 Caprice rode like crap. Bags always ride better, right?

A: Umm, no. First let's talk about the Caprice.

A Caprice is just like a FSC in that it has the same front suspension. That means it probably was coil under without a shock, and probably had hopping coils up front, giving it a harsher ride. Sound correct?

Well if he had run stock coils with shocks, or even accumulators at the correct pressure, he wouldn't have had ride issues. I'm willing to bet though your friend wanted to hop, not ride great. With hydraulics, you've got to make compromises if you want high hopping ability.

On top of that, a bags ride quality depends on the pressure in the system. With a hydraulic setup, the ride is almost always constant, unless the system compresses the coil flat or the accumulator is maxxed out. That's called "Locking out" the system. The pumps cannot push anymore pressure, and so everything is stiff.

Q: What about fires?

A: Fires. Its happened to me, but that was when I was young and nieve. Here's why it happens.

If you run a standard battery, it has battery acid in it. It also needs water to be maintained, and it also can heat up the plastic casing pretty well if pushed to its limits.

Fires don't just happen, there has to be a catalyst. With hydraulics, if you hop it for an extended period of time, you have a loose ground which causes a spark, or if you've heated up the pumps so much that the batteries are burning, what can happen is that a terminal on the battery will melt into the casing and shoot flame out.

So what do you do to stop it?

1. Run gel cels. A gel cel doesn't work the same way, and the battery acid won't lite up, since its a gel. At least I've never seen an Optima on fire.

2. Know the limits of your setup. Don't push it too hard for too long. If your pumps are hot to the touch, stop! Let things cool down. Otherwise problems can happen.

Q: Hydraulic fluid is messy. Air is so clean. Why would I run juice?

A: Lift, ride, power, need I say more? Look a hydraulic system only leaks if its not assembled or maintained properly. Tight fittings and seals that are up to date keep that up. Also if you have a leak, fix it! Don't let that leak piss fluid all over your truck! It's all about laziness really.

Q: Bags are easier to install right?

A: Not really. You can yank a coil and put in a bag just as easily as you can yank a coil and put in a cylinder. Took me about 3 hours to do the front of my truck, and it'd be the same with bags b/t cutting the cup for the bag and so on. As far as the rear is concerned, it's the same way. Make mounts, you're good to go. The only thing you have to consider is the size of your rams. Otherwise you're kosher like pickles.


Ok now I'm done. I'll open it up to q&a. Any q's, ask away. Please, no slander, no juice knocking just because or anything like that.

 

[00Silverado]

Kevin, excellent writeup, stickied it for you :head:

 

[Silvlowrdr]

Sick write up bro. Now for the Q's. Well i ran out of money while i was doin my truck this winter, so its off the road again for round two. Now that its apart, i'm thinkin about running four pumps. Any pro's and con's for me??? I hope it'll be a lil quicker and maybe a lil more fun to play with. FYI i'm runnin 6 batt's and accum's with some shutoff's so i dont blow them when playin hard. Thanks

 

[kdubaz]

Thanks for the complements.

Ok Silv, here's the deal. I LOVE 4 pump setups. They really are the easiest to install, because it's a-b installation. Plug a into b, etc. Anyways the main issue you're gonna have is cost. You've gotta buy 2 more pumps, 2 more solenoids, and more wiring. On the plus side, you've probably got all the fittings you'll need to plumb it up in your existing 2/4. Wiring it is going to be different too, depending on your switchbox and if you did it yourself or if you bought a pre-wired one.

I don't really see a whole lot of negatives to the setup really, other than the amount of space it takes up. 4 pumps aren't tiny, and it'll have a pretty big footprint in your bed or wherever they're mounted. You will go through your batteries quicker, but it's gonna be a grip faster too, so you won't notice the slow down in battery power as much.

On the plus side, your pumps are going to last a lot longer. They'll be doing 1/2 the work they were doing before. Plus its a ton faster. Lemme know how it turns out!

 

[Silvlowrdr]

i think i'm gona go for it. gonna take a few more paychecks but what the hell. Startin to pick up one yellow top a week so its not a hard hit for 6 batt's at once... but i was wondering how hard 8 would be on the solenoids and motors. I know i'd have to run four solenoids, but would it make the motors burn out quick. Its for the most party a daily driver. Tryin not to but for now it has to be. Thankz

 

[kdubaz]

Silv -- Stick with 6 batts. For a daily driver with accumulators, go 6. It'll make your life easier.

Matt -- If we're talking same speed and ride, it's about the same, with hydraulics running maybe $100 more. There are a lot of factors involved obviously, but with hydraulics you can have the same ride at ANY height, and frankly that's a big advantage.

 

[Silvlowrdr]

Whats the difference between the LA series pumps and the pro comp pumps. I know the pro comps are better than the pro x but i dont know anyone with the la series. Thanks.

 

[kdubaz]

The LA series, if I remember correctly, has larger ports for faster speed. Take in mind it's only going to be as fast as your smallest fitting, so unless you've got 1" ports on your cylinders, you're not going to notice a huge diff. They may have different motors too.

 

[gtphelps]

Here is what a 2/4 with accumulators can look like.

 

[Kal]

What do you say gtphelps I come and check that sweet truck of yours someday? :rocking: I don't think your that far away from me.