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21 Aug

TrailerTech: Reusing Tie Plates

Welcome back to TrailerTech!

We all know you shouldn’t re-use u-bolts when servicing or modifying your trailer’s leaf spring suspension. Tie plates though, aren’t as cut and dry. There are obvious qualitative observations that can be made, such as the presence of rust or total failure. Structural integrity is a much different story. At a casual glance, tie plates often appear unchanged after a use or two. In this TrailerTech article, we’ll take a closer look.

Lateral bending is one of the biggest concerns when assessing a tie plate’s structural integrity. The tie plate flexes across the leaf spring, bending towards the u-bolt’s clamping force. The photo below shows an unused tie plate on the left and a tie plate torqued down only once on the right. Notice the slight circular markings from the u-bolt washers.

A keen eye will also notice the slight arc in the tie plate on the right (a 1mm rise). This might not seem like much, but if we graph the result, the deflection is much more apparent.

Naturally, the proper care must be taken when re-using tie plates, as lateral bending is not always visibly obvious and a closer inspection is necessary. If you have any doubts about your existing tie plates, the safest thing to do is to replace them along with other one-time use parts, such as u-bolts.

We hope this TrailerTech article is helpful when making your assessment.

06 Mar

TrailerTech: Measuring for Lift

Welcome to TrailerTech!

We’ve heard from a few customers, wanting to know how much they should raise their trailers. This is something that should be evaluated on a case-by-case basis. Adjustments in your trailer ride height should be made with the consideration that your trailer should be riding level with the ground behind the towing vehicle.

A quick tip to help envision your adjustment in ride height is to find 1”/2”/3” boards to use and back your trailer onto them to see how the overall height would be changed after a Trailer Blocks installation. Depending on your situation and desired lift, you may choose to use ramps, jacks or a combination of boards to achieve the desired result. Staggering boards, as shown in the picture below can make it easier to move the trailer on and off.

Measuring for Trailer Blocks

Trailer Blocks are sold in 1”, 1-1/2", 2”, 2-1/2", and 3” height variants.

22 Jan

TrailerTech: Trailer Blocks Safety Questions and Tips

Welcome to a new installment of TrailerTech! Today, we’ll take a look at some questions and comments lately that we’d like to address.

The proper installation of our products is of major concern for us and as such, we actively strive to aid our customers with any technical or safety-focused questions they may have. Inquiries such as “Are lift/lowering blocks safe for use on my trailer?” have made their way into our inbox and we’d like to offer some information and tips on some common concerns we’ve seen raised.

Changes in Vehicle Height

Changing the height of a vehicle will always change vehicle dynamics, period. We have assembled some tips for lifting and lowering your trailer.

Lifting: Despite raising the trailer’s center of gravity, it’s important to note that a level trailer is far more stable than a low, but improperly leveled trailer. 1”- 4” blocks will keep the change in overall ride height small and minimize the added mechanical advantage the axle has on the suspension. A rule-of-thumb to use when working out an appropriate lift is to keep the ride height change within 5% of the overall vehicle height. For example, adding a 3” lift to a 10 ft. tall travel trailer would result in a 2.5% change in the ride height, which is acceptable.

Lowering: When lowering a trailer, clearance becomes the major factor. Once again, 1”- 4” blocks will minimize the added mechanical advantage the axle has on the suspension. Generally speaking, a standard trailer suspension will accommodate 1” – 2” blocks without modification. When lowering a trailer 2.5” – 4” it is advisable to switch to a standard 4” drop axle, and adjust up or down with blocks and axle placement (above or below the spring) to achieve the desired ride height.

While discussing changes in vehicle height, we talked about the added mechanical advantage the axle has on the suspension with the additions of lift/lowering blocks. This can be broken down into two categories: axle wrap and wheel scrubbing, explained below.

Wheel Scrubbing (lateral twisting)

Wheel scrub is fairly common in tandem axle situations. Since the center of mass is between the axles, maneuvering a trailer in a tight area causes it to rotate on its axles. One axle shifts to the left and one to the right, causing the axles to appear misaligned. This situation is present on trailers with or without modifications to the ride height. Wheel scrub can look unnerving, but leaf spring suspension is well suited to dealing with this due to its excellent lateral rigidity. It’s important to remember that the forces the suspension encounters under hard braking are actually greater than those encountered during wheel lockup or wheel scrub. A locked wheel behaves in a similar manner to a wheel in scrub, in that they are both not rotating with respect to the road with low friction between the contact patch on the tire and the road surface.

Axle Wrap (longitudinal twisting)

Axle wrap, or longitudinal twisting of the leaf spring occurs when torque is applied to the suspension, forward or aft, in the form of acceleration or braking. It is the leading cause of concern when using blocks on a driven axle or, the front axle of a vehicle, as the block can “squirt” out under extreme torque. The axle is not driven on a trailer and the condition known as axle wrap does not occur under acceleration under normal circumstances. But trailers have brakes, this means the axle is subjected to axle wrap under braking. Tires on an axle that is not driven and not the front axle of the vehicle, experience wheel lock-up before axle wrap overwhelms the spring. This means that the maximum amount of axle wrap occurs at impending wheel lockup. The leaf spring by design is well suited to absorbing forces acting longitudinally on the spring. Adding suspension blocks to a trailer will increase the effects of axle wrap caused by braking. Increases in axle wrap, wheel scrub and changes in vehicle height, are non-issues when adding lift and lowering blocks to trailers using axles with a gross axle weight rating (GAWR) of 3000lb to 7000lb as long as you follow some simple guidelines:

  • Use only SAE Grade 8 U-bolts with rolled thread.
  • DO NOT re-use U-bolts under any circumstance. If re-used, U-bolt clamping force is reduced by over 55% even though your torque wrench reading is identical. U-bolts should never be used with lock washers, they will fatigue, break and fall off.
  • U-bolts must be torqued to the manufacturer recommendation. If U-bolts are under-torqued, they may loosen. If U-bolts are over-torqued, they can exceed their ultimate tensile strength and break.
  • Carefully assess tie plate wear, it is a good idea to replace tie plates every time you replace U-bolts. Ensure the tie plate is strong enough to support the required U-bolt.
  • Use only solid billet aluminum Trailer Blocks that will resist crushing forces.
  • Always ensure that springs, spring clips, shackles, suspension bolts, bushings, and mounting brackets are in good, lubricated condition (up to date in the case of a dry system) and are free from corrosion.

Maintaining these components with regular upkeep is as important as any regular trailer maintenance routine with or without ride height modifications.

By following the above guidelines, lifting or lowering your trailer with blocks is a safe and effective way to modify the ride height of your leaf spring trailer. It ensures your rig is kept level, and it opens up a diverse selection of wheel and tire options to improve on and off-road performance.

We got hope this helps clears up any questions or concerns. If you have any technical issues of your own you’d like us to talk about, please send them to: contact@trailerblocks.com

More entries and updates coming soon.

11 Jan

TrailerTech: Stainless Steel Fasteners in Steel and Aluminum

Welcome to the first installment of TrailerTech!

We’re launching this new addition to the blog lineup to share some technical details, facts and tips that can help you with your trailer performance endeavors. Today, we’re covering a common misconception that we’ve seen crop up over the Internet. According to some, stainless steel bolts aren’t necessarily a good idea to use in carbon steel or aluminum beams due to the process of galvanic corrosion. Our team has observed a few things during some in-house testing and we’d like to take a minute and help clear up some misconceptions.

Galvanic (or bimetallic) corrosion occurs when two different kinds of metal come into contact and are exposed to an electrolyte (rainwater, groundwater, mud, saltwater etc.) which causes an electrochemical reaction. When this electrical process occurs, one metal acts as an anode and the other as a cathode. As a result of the galvanic connection, the anodic metal decays at a much faster rate than it normally would and the cathodic metal decays much slower. Eventually, this connection causes the anodic metal to dissolve and deposit its remains upon the cathodic metal, causing rust to form.

So how big a deal is galvanic corrosion when using stainless steel hardware to fasten stuff to your trailer's frame?

To test this in-shop, we chose 300 series stainless steel due to it's high availability and common use as a fastener. We observed that although the galvanic connection is still made with electrolyte exposure, the shear size of the anode (the ample frame) greatly decreases the rate of decay. In fact, no galvanic corrosion was detected. Overall, we have found the effects of galvanic corrosion of 300 series stainless steel in carbon steel or aluminium to be greatly overstated, and consider the practice to be safe. The key understanding being that no rust is formed due to the small relative size of the stainless steel fastener within the larger piece of carbon steel. For extreme duty applications, such as continual salt bombardment during the winter time, prolonged use in saltwater or prolonged exposure to mud, a zinc chromate primer can be applied prior to assembly with stainless steel fasteners.The frame should be coated first, let dry, then the fastener coated and inserted wet. It would seem that the benefits of rust-resistant stainless steel hardware for trailers greatly outweighs the infinitesimally small risk of galvanic type corrosion.  

We hope this has provided you with some insight into using stainless steel fasteners in carbon steel or aluminium. We have more informative topics lined up, so keep an eye on the blog.

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