Wednesday, November 23, 2011
Black Friday Sale 2011
The sale will last the full 24 hours of Friday. Enjoy!
Thursday, September 8, 2011
Competition 4x4 has begun manufacturing tire carrier spindles
Previously we purchased all our 1-1/4” and 1-3/4” diameter spindles through another manufacture for a couple reasons. One, they were fairly cheap due to our quantity price break on large purchases. Two, they were easy to order and arrived in a couple days, so we didn’t need to worry about manufacturing another product in our mix.
However, over the last year the prices have steadily increased to the point that they have doubled in price. We even received word from the manufacture today that there will be another 6% - 18% increase on current prices! We also started receiving some spindles that would come bent upon arrival of the threads would be smashed during shipping. Well, we have had enough!
Two weeks ago we began manufacturing the spindles on our CNC lathes. They are produced from the same material as our previous provider and to the same dimensions. There are a few added benefits to our customers now that Competition 4x4 produces the spindles. One, we control the process and therefore are able to machine each item to exact specifications at a higher rate of quality. Two, we are able to save money and therefore pass the savings onto the customer by not raising prices on our tire carrier hinge kits as we would of needed to do with our previous provider. Three, we are able to provide quicker turn-around times and hold a more level quantity on hand.
The only drawback is that the previous manufacture provided a load rating of 1000 lbs. on the 1-1/4” spindles and 1750 lbs. on the 1-3/4” diameter spindles. Although we are machining the spindles from the same material to the same specifications, we have not conducted fatigue stress testing on the tire carrier spindles and therefore cannot advertise an exact load rating.
Why haven’t we conducted fatigue stress tests on the spindles you ask? The answer is bling-bling…as in money, lots of money! There is only a few metallurgical testing companies we found (most in California) that seem to have enough brains to properly setup the spindles in a jig and provide fatigue stress tests. They first have to do a compression test to see how much static load the spindle can bear before it snaps or shears off. They then take a percentage of that load and begin a fatigue stress test scenario (involves applying pressure and then releasing and repeating) over one million cycles! If it survives one million cycles, then it definitely deserves that load rating.
It’s unclear if the current manufactures on the market are providing a load rating of 1000 lbs. and 1750 lbs. for a fatigue stress scenario or compression in static load. The price for each test is around $7K - $8K. And since we will have 3-4 types of spindles to be tested and each in two material types = 6 – 8 spindle types. Some may need multiple tests to find the correct load for one million cycles. Calculate that all up and were looking in the ball park of…a lot of money!
At this time, were just not going to spend that kind of money on testing a spindle that we know uses the same material and specs. We will however test other spindles in the future that we plan on using, especially those with different materials (for example, 4340 chromoly – post heat treat).
We will most likely first provide a static load rating – how much a spindle can hold with continuous pressure until breaking - opposed to a fatigue stress test.
Until then, just know we are using the same materials (A36 HR) so as not to deviate from the other manufactures load ratings. However, for insurance reasons, we cannot claim the same ratings.
Any questions? Feel free to contact us or check us out online at comp4x4.com
Monday, June 13, 2011
Why tire carrier hinge kits using a trailer axle spindle break, crack, or snap
Why would we have the answers? Most of the fabricators commenting on the occurrence of the broken spindles either have a ‘friend’ or ‘brother-in-law’ that is a mechanical engineer or rocket scientist or some other reason of why they are a 110% right in their reasoning. We however have a full-time mechanical engineer on site with training in metallurgy. Although I personally have an MBA, I have a background in engineering with training in metallurgy as well. We also have our spindles tested by a metallurgical testing service in Utah to provide sound results. That being said, we have sold and used these spindles since 2002 and as such have a sound understanding of why they fail and what you as a fabricator, installer, or designer/engineer can do to prevent it.
** It’s also important to note that out of the one thousand plus spindles we have sold, we have only had one customer report of a failure. The failure was due to improper design, load, and bracing.
First off, let’s debunk a common misconception.
“Trailer axle stubs (spindles) don’t break on the trailer when you weld them, so why can’t you weld them on your tire carrier? Your sleeve design is smoke and mirrors.”
A spindle installed in a trailer application is welded directly onto the axle tube at the base of the spindle with the remaining 5 +/- inches exposed for mounting. The tire is then mounted with the bearings etc. onto that remaining 5 +/- inches of the spindle. All the pressure put on the spindle from the trailer is concentrated onto that area of 5 or so inches. Because the length is so short, the amount of bend stress inflicted on the spindle is greatly reduced.
Now imagine that you removed the tire from the spindle and then installed a 48” long extension tube onto the spindle. At the spindle end, you still use the bearings etc. and tightly secure it to the spindle. At the other end, you install the tire. Now drive around town with a load in your trailer and see what happens to the spindle. The bend stress is greatly increased on the spindle due to the extension of the tubing. All the force is now exerted onto the base of the spindle where it’s welded to the axle housing. There is much more flex, vibration, and movement in the spindle due to the extension. As such, its chances of failure are increased. The welding becomes much more critical in this example as opposed to the standard trailer setup.
For this reason, you can’t compare a trailer to a tire carrier as the application is different as well as the stress inflicted on the spindle.
How do you resolve this issue?
Because the spindle welding is far more critical in the tire carrier application, we eliminate the process at the base of it. Most all spindles that you will find that have fractured have failed at or near the base area of the spindle. This is also were they are commonly welded into the bumper.
A common welding error is excessive heat which causes the area to become brittle. The second most common welding error is quick cooling. After a hot weld, many people will throw wet rags on the area, spray it down, or dunk it in a cooling tank to quicken the cooling process. In this critical application, it also weakens the area and makes it more brittle. For those of you not using our sleeve design and wish to weld it anyways, make sure the area is welded at the correct temperature for the material thickness. After welding, provide a slow and even cool down for the entire area. This can easily be accomplished by laying thick leather over the weld area to keep it hot and insulated.
Competition 4x4 however uses a sleeve design to eliminate the need for welding at the base of the spindle. The sleeve also offers the option of a standard height for setting up your tire carrier using the provided drilled hole and roll pin.
The sleeve on our standard 1000 lb. spindle kits in single shear and dual shear applications have an outside diameter of 1-5/8” while the 1750 lb. spindles have a 2-1/4” OD. The sleeve gets tack welded into the bumper with the spindle inside of it. Once the correct height setup is determined, you can then fully weld the sleeve to the bumper top and bottom (with the spindle still inside of the sleeve at the desired height). The inside diameter of the sleeve will shrink and pressure fit onto the spindle. For added measure, we recommend putting two light tack welds on the bottom of the spindle to the bottom of the sleeve.
You can view full installation instructions on the sleeve and tire carrier hinge kit on our site at: http://www.comp4x4.com/instructions/Dual-shear-tire-carrier-hinge-kit-installation-03.pdf
The use of the sleeve therefore eliminates fatigue and fracture of tire carrier spindles due to welding.
The spindle can still be fatigued if the tire carriers overall design is poor or has excessive weight. The next most common reason for failure is that of a poorly designed latch that allows side-to-side and forward-to-back movement. Competition 4x4 is currently working on finalizing some latch designs to be laser cut that will box in the latch end of the tire carrier to eliminate movement in all areas. This will eliminate the flex suffered by the spindle from poorly designed latches.
Lastly, the excessive weight from some tire carriers is just too much. Many designs have an over the tire rack/cooler area, two Jerry cans, and a hi-lift jack etc. This is a lot of weight in addition to your wheel and tire. In order to provide the strongest solution, we offer our tire carrier hinge kits in a dual shear design. We have a ‘Z’ shaped bracket for our standard upright tire carrier hinges that tie in the top of the spindle and bolt the whole assembly to the bumper. This reduces all the flex that would be suffered by the spindle and transfers the load to the bracket.
We also have dual shear designs for mounting onto the face of a bumper or any other angle. We also have designs that use a 1” bolt instead of a conventional spindle setup.
Competition 4x4 is committed to providing solutions to all tire carrier systems. We have more tire carrier hinge kit designs that any other one manufacture. All our kits are CNC machined and laser cut to provide the best quality and performance. We are constantly improving and adding new designs and solutions to our product mix.
You can view all our tire carrier hinge kit options on our website HERE!