Tuesday, September 30, 2014

Voltage drop testing

Voltage drop testing

Voltage drop testing is the best way to find electrical faults, at least in my opinion. So what is voltage drop? First of all a couple basic things about electrical circuits. Circuit means circle, electricity must complete a loop in order to have electron flow. If a switch is open, or a break in the wire there is not a flow of electrons, and electron flow is needed to perform work. The pressure needed to get the electrons to flow is voltage. A volt meter reads the difference in pressure between the two leads, that is all it does. For example if you connect your volt meter to a fully charged 12 volt battery the difference in pressure between the positive and negative posts should be about 12.66 volts. But if you touch the leads to each other there will be no pressure difference between them so your reading will be 0 volts. The same if you hooked up your leads to each end of an isolated wire, 0 volts. There will be a slight drop in voltage though, because perfect conductors don't exist. So if we have some kind of restriction in our conductor, maybe a bad connection, a loose crimp, corrosion, or some broken strands in our wire, these restrictions will cause a drop in the pressure of the electrons flowing through the wire. And we can measure this loss of pressure with our volt meter or dmm. (digital multi meter) But the circuit we're working on has to be operating with current flowing in order to perform voltage drop tests. And the voltage reading you get will be proportional to how bad the connection is, or corrosion, or broken wires, or whatever the problem is causing the unwanted drop in voltage. When a load, say a light bulb is in the circuit we should have source voltage coming into the load, in this case 12.6 volts. The positive lead on the dmm would go to the point of highest voltage in this simple circuit. That would be the positive battery post, NOT the battery connector or clamp but the post itself. Then place the negative lead on the dmm onto the positive wire or input of the bulb. This will check the entire positive side of the circuit from the battery to the bulb. There will be a slight drop in voltage compared to our 12.66 across the posts. There is a very slight voltage drop at every connection and switch in the path, and the longer the wire, the more voltage drop there will be. Say we had a bad switch on the positive side of our circuit, it would drop some of our voltage, say 2 volts. Our bulb would still light but it would be dimmer than it should be. So you can work your way back to isolate the voltage drop, You can even put the positive and negative leads on the in and out terminals of the switch. If you have 12.5 volts or so going into the switch and only 10.5 coming out, you have identified the problem, the switch could be bad, or the connections could be loose or corroded. If you test between the input and output sides of the switch, there should be 0.0 or just slightly more difference in the reading. If it is much more, the switch or connections are bad. But you must always check the negative side of the circuit also, it is just as important as the positive side. When the circuit is working properly, the load uses all the voltage. (Or almost all, there will still be a small amount) So if our simple light bulb circuit was working properly, we could check from the positive post of the battery. (I say the post and not the connector or battery terminal clamp because this will test the connection of the terminal to the post as well) to the input or positive side of the bulb. Generally the voltage drop should be 0.1 volt or less. Then we need to check the negative side of the circuit as well. Place the positive lead of the dmm on the negative terminal of the bulb, and the negative lead to the negative battery post on the battery. If the reading on the dmm is not 0 or 0.1 or very close to it you have a problem on the negative side, possibly a poor connection or corrosion is causing the unwanted resistance. When testing I like to run a ground wire directly back to the negative post of the battery, this will eliminate any chance of grounding your dmm to a poor ground and getting faulty readings. Some people prefer to disconnect wires and test using the ohm setting on their dmm, you can do this but say you have a wire with corrosion on the inside of the insulation, or all but a couple strands of wire are broken. You would still get a good reading with an ohm meter continuity test, but the circuit would not operate correctly under a load. Or if you take out a dim bulb and check the voltage on the positive side of the bulb, you will get a good reading of 12.6 volts on our circuit but it won't light up nice and bright with the bulb in. But you would assume the wire to the bulb socket to be good when it is not. Very often corrosion is hidden inside the wire's insulation and you don't see it by looking, this corrosion reduces the wires ability to carry the amount of electron flow needed. Some guys poke holes in the wire insulation when testing, I never do this, because that is just inviting corrosion into the wire. But if you insist on doing this, at least seal the hole you made with some of your wife's fingernail polish or something. Don't use silicone though it creates ammonia which causes corrosion. Again I think the voltage drop test is the best way to find electrical problems. If I'm helping a friend or someone with his jeep or car even if the problem is not electrical I do a couple basic tests, like checking engine and body grounds. Connect the dmm between the negative post of the battery and the engine , and with the fuel pump disabled crank the engine a few turns and check the volt reading it should not be more than 0.5 volts at the most, lower numbers are better. Then check between the negative battery post and the firewall with the engine running and all the electrical loads turned on, again the lower number the better. If anyone is interested I will post some other tests to perform. 
 
 
source:http://www.xjtalk.com/showthread.php?p=189893#post189893

Monday, September 15, 2014

idea for tire carrier

good design



source: http://www.cherokeeforum.com/f59/official-bumper-thread-123935/index7/

Sunday, September 14, 2014

Sunday, August 31, 2014

Engine Cooling Fan Controller-Temperature Switch HAYDEN 3653

Installed HAYDEN thermostat for my electric fan

control unit

thermostat fitted near top coolant hose, behind   radiator


circuit powered by IGN activated 12V source from in cab fuse box and fan override switch installed below dash, near driver side door





Sunday, August 17, 2014

water pump replacement

had a small leak at water pump hole and heard some bearing noise from water pump. Decided to replace and ordered Gates one from Rockauto.















Saturday, August 16, 2014

fabbing Rear bumper end

decided to make an end cap for my rear bumper.

cut existing bu,per for new end design




finished and looks good


starting

cut & fold


welding fold lines from inside


finished welding and now time to grind





spray painted, ready to hang

final look




side view







Monday, June 30, 2014

Chinese XJ with a frame

found this car from friend's backyard. Did some googling and found actually it is chinese Shunghuan brand, called Shjzh213.

The car have an frame, big drum brake front axle, front locking hub (wanda?), front and rear leaf springs. Unfortunately engine, transmission and rear axle was not there, short drive shaft in between transmission and transfer case.

see the photos:










here is some photos from chinese forum

http://bbs.360che.com/thread-342131-1-1.html

Which grease should I use?

http://www.xjtalk.com/showthread.php?p=187454#post187454 

Which grease should I use?

The following is from Off-Road.com

We’ve all been there – staring at the business end of an anti-roll bar or A-arm or a random Zerk fitting, thinking to yourself: “Self, what kind of grease am I supposed to use?” While the answer to that question varies wildly, the places we all seek out those answers do not. Do you ask a mechanic? Which mechanic? What about the guys at the off-road shop that you bought the parts? They’ve probably sat and stared at the same parts you’re staring at. How about you get a hold of the people who make the grease and see what they suggest?

Of course, there’s more to this story than “What do I use?” That’s because there are about a bajillion greases on the market out there, and even though you’ve used one kind or another for this or that application, were you right to do so? Did you know what you were doing? Does someone else know more about grease than you?

This could have been a greasy this-for-that list, but you wouldn’t have enjoyed it very much. Instead, we reached out to people who know a few things about greases – especially in off-road settings – and knocked them about with our greasy questions. Most of these greasy folks work on the money-making side of the wrenching business (rather than the money-spending side, where the rest of us live), so they had lots of tales about greases they’ve known and loved, how to show grease a good time, and what they recommend when it’s time to grease: Chris Barker with Royal Purple; Brandon Schaub and Gerard Wagner at Tony’s Lube & Tune in San Diego; Jason Edwards and Jeramie the Mechanic at ORW in El Cajon, CA. This casual collection of mechanics and grease monkeys, plus a real-life manufacturer’s rep, had a lot to tell about different greases. Will any of it answer your questions?

A close-up of Royal Purple’s Ultra Performance #2 provides a good idea of how thick and stringy a sticky synthetic grease can be (and #2 isn’t the thickest).

It Begins: What Grease for Urethane Bushings?
Speaking of staring, this story sprung up while glaring at a set of urethane bushings for some upper A-arms on a Toyota. While we had used the as-specified grease for the arms when they were installed (a sticky goop supplied with the arms), there wasn’t a lot and we’d used it up, and the bushings had started squeaking again. The Zerks feeding those bushings were begging for a shot of grease from the gun full of bearing grease in the garage, and we tried a shot of it, but it didn’t last. The high lateral loading and constant movement of the upper A-arm worked the axle grease right back out of the bushing, and they began squeaking again in a matter of days.

In search of suggestions, we paid our buddies at Off-Road Warehouse in El Cajon a visit. Jason and Jeramie agreed that a Lubrication Engineering grease they called “gorilla snot” or “the red stuff” was good for this application. They’d used it before – the official name was Almagard – and the variable-purpose grease had been very durable. It was a tacky, lithium-complex grease that water didn’t bother much (good for the summer high-mountain, creek-fording season). Jason said he’d been recommending it for years, and he’d used it for everything from springs, rubber, poly, and the ceiling fan in his living room. Jeramie at ORW added that he likes to use the red stuff on aftermarket and HD truck ball joints.

Gerard with Tony’s suggested Lucas’s Red & Tacky #2 for poly A-arm bushings.

To get some of the science behind our grease questions, we sought out Chris at Royal Purple – he’s been on the manufacturing end of the grease business for 10 years. When we asked Chris the poly bushing question, he smiled and stated that he gets it a lot. He suggested Royal Purple’s Ultra Performance Grease #2, which is good for most chassis points that need the grease to stick around (and is made in the U.S.). He added that the numbers on grease identify the firmness of the grease, and that almost all multiple-application greases are #1, 2 or 3 (mostly #2), and the lower the number, the thinner the lube. A #0000 grease flows like oil, while you could mug someone with a #6 grease. Clunky “brick” greases like a #6 are used in situations where heat will melt them, such as with steam engines, oil wells or a compound mill.

Chris has been a Texas oil eater for a long time, so he had a lot of knowledge to share:
• A grease is the combination of a lubricating agent and a suspension agent.
• There are very few greases that are bad for polyurethane.
• It’s an old wives’ tale that poly elastomers don’t like petroleum-based lubes. Most polyurethanes or Delrin are stable and inert in the presence of mineral lubes.
• Rubber, on the other hand, doesn’t get along with the dino-based stuff – just leave a rubber bushing in a rock-juice bath for a few weeks and watch what it does.
• The color of a grease only means someone wanted to make it that color: there are very few chemical causes for what’s colored what (that’s why ATF is red, for example – someone said so). This even goes for Royal Purple products – they’re purple because Royal Purple isn’t named Royal Green.
• The only “sort’a” exception to grease coloration is greases with molys in them: molydnum or molydnum disulfide. The graphite in these means they’re always going to be the color of graphite.
• Sticky greases are sticky to keep the lube where it was applied. A tackiness agent in the grease does the heavy lifting; in some cases, it’s formulated to “string” as a part of its function. The type of stickiness is usually specific to each application, and temperature tends to affect a grease’s stickiness.
• Check parts manuals for exact grease instructions. It’s common to see a thickness requirement (#2), but specs about specific greases for specific bushings are rare.

Gerard at Tony’s Lube & Tune in San Diego has been wrenching longer than most of us have been alive. When he was asked the same question about polyurethane bushings, he simply declared, “Something that will stick around. And USE it – don’t be cheap.” He agreed that checking the part manufacturer’s specs was a good idea, and then reminisced about a grease Chrysler used to make for its front-drivers in the ‘90s that was the stickiest he’d every seen (even tackier than the #2 Lucas “Red “N” Tacky” grease he uses now as his “sticky” grease). Gerard said the Chrysler grease was “stupid-tacky” – staying in place “forever” – and was ideal for high-temp and high-pressure applications. Gerard proceeded to bitch for five minutes about not being able to get it anymore, which made the effort of interviewing him totally worthwhile.

Jeramie at ORW made the same point Gerard had – don’t skimp, and don’t miss Zerks. The guys at ORW had a lot of off-road info: it helps to ask the specialists when you need specialized info.

Getting Grease on Bearings (and Keeping It There)
While Gerard was sounding off about the worldwide conspiracy to keep him from having good grease, Brandon from Tony’s had a few minutes to talk about how much he enjoys packing axles and bearings. He’s a boat guy, and has gotten hooked on using marine grease for almost all big boy bearings instead of regular bearing grease. This went doubly for extra-load, heavy-duty applications and trailers. He does a 100%-pack on boat trailers and any vehicle that might see deep water (trail guys: are you listening?), because any holes in the grease pack of a bearing will let water in – Brandon likes to make sure the water doesn’t have a place to go. He’s also a big fan of using a Bearing Buddy to keep whatever grease is at hand on the bearings where it belongs (trailer-supply stores sell these).

Jason and Jeramie at ORW had the same advice about packing bearings – a little grease on the outside won’t do the job. If you can’t pack bearings by hand, get the tool and use it. Jeramie likes what he called “standard blue” high-temp wheel bearing grease for most axle and high-load bearing applications (and insisted that you need to use a high-temp grease that’s made for bearings), though he suggested the stickier Almagard (the red stuff) for trucks with small bearings like Rangers, because they move faster and tend to cook and subsequently sling wussy greases. Jeramie added that “the red stuff” is good for applications with a lot of heat because of its stickiness, while he likes Swepco 101 moly grease for U-joints because it works to keep water out, and the moly cuts down on friction – even when the grease is gone there’s still a little graphite hanging around (just in case).

Jason at ORW enjoys grease – can’t you tell? At least, he enjoys these greases, because they work great for the SoCal desert and buggy guys.

Jason added that a popular constant-velocity (CV) packing trick that many SoCal sand and buggy builders like Jimco and Alumicraft use is to fill the CVs with a 50/50 mix of Swepco 101 moly grease and Bel-Ray’s astronomically-priced anti-seize, packing them in super-messy handful-of-goop fashion. The 50/50 blend goes in as a paste, won’t separate, and stays there as long as the boot is intact. He said that with some axle grease, the same combo works for standard half-shaft CVs, but stated that if you’re going to try it, bring your purse because it’s not a cheap mix to make. Gerard at Tony’s cautioned against mixing moly greases with lithium greases, however, and then bitched about moly greases for five minutes (again, worth the price of admission).

Some More Science - Greascience
Chris from Royal Purple cautioned everyone who’s seeking, using or recommending greases that words have meaning. Call a grease by its specific name – what it is – and avoid using slang terms. Moly could be molydnum, or it could be molydnum disulfide – they’re not the same thing and both do different things. He also reminded us that grease is not oil – grease is an oil plus a thickener, and that thickener (with whatever else has been added to the grease’s formula) is designed to hold the lube somewhere, make it behave in a certain fashion, keep some in reserve, or stop it from leaking. You use greases when you can’t keep the oil from leaking because grease stays put under pressure, and in extra-hot applications. Mechanical devices need to be able to count on grease to perform, maintaining its film strength and sticking around, and good formulas mean good performance. Chris was also adamant that you get what you pay for with any grease product, which is why Royal Purple sells a lot of grease.

Brandon from Tony’s reached into a shoebox full of spare and unused specialty grease packets to remind us why it’s smart to keep the leftovers.

Some more thoughts about grease from the guys:
• When you inject grease with a pump grease gun – which can exert a lot of pressure – rubber and urethane bushings can be “mushroomed” out of place if there’s no route for the injected grease to flow around the bushing. Be sure to give the grease room to move without pressurizing and distorting the bushing. In case you do overpressurize a bushing, yank the fitting (Zerk or otherwise) to see if the bushing will depressurize itself.
• Jeramie likes anti-seize for parts that are hard to service, like leaf spring bushings.
• Coat replaceable poly bushing with your choice of grease when you’re installing them.
• For the slip-joint in a driveshaft, use a high-temp wheel bearing grease.
• We started seeing sealed ball joints in the ‘90s, and this trend may spell the end of Zerks on new cars. Gerard suggested it was Mercedes-Benz’s fault, and then spent five minutes bitching about German cars (keep in mind, his last name is “Wagner”).
• Don’t feel silly hoarding the spare grease packets that come with suspension parts – Brandon’s been doing it for years, especially the grease that comes with poly parts.