A Joint for Any Occasion
By Bill "BillaVista" Ansell
Bill Ansell Copyright
2005 - BillaVista Offroad Tech
2005 - BillaVista Offroad Tech
There are many choices on the market today for suspension-link joints. A wide selection is a good thing, but it can also make the decision more complicated. And the decision is an important one. In today's multi-link suspension, there can be up to 16 or more joints - all of which are going to have a profound effect on how the suspension performs and the durability of the rig, as well as your budget - buying 16 joints can add up to serious money pretty quickly. Choose the wrong joint and you may not get the most out of your carefully designed suspension. You might also find yourself rebuilding or replacing joints more frequently than you'd like.
|The selection of the joint for the suspension link is also at least as important as selection of the tube. Having destroyed countless rubber and poly bushings I am a firm believer in using some sort of cartridge-style joint or spherical rod end (Heim joint). For this article I evaluated and reviewed three of the best. Shown in the pic at left, from left to right are the Rubicon Express Large Cartridge Joint, the Evolution Machining and Fabrication Rebuildable Heim Joint, and the Poly Performance Uniball.|
In selecting a joint, there are a number of factors to consider:
The following table provides a comparison of the basic specs of the different joints.
|RE (large) Bearing||Poly Performance||Evolution|
|Bearing Material||Chrome-plated steel||Ball – 440C heat treated
Race - 17-4 PH heat treated stainless steel
|Body diameter (D)||2-5/8"||2-5/8"||3.0"|
|Body Width (W)||1.875"||1.750"||1.625"|
|Bearing width (B)||2.625"||1.375"||1.750"|
|Spacer width (S)||built in||2 x 0.815"||2 x 0.50"|
|Total mounted width (M)||2.625"||3.000"||2.750"|
|Bolt hole (H)||9/16"||3/4"||3/4"|
|Shank thread||n/a||n/a||1.250 - 12 UNF|
|Tubing Size||Up to 2" OD||Up to 2" OD||1.750" ID|
|Misalignment||23 degrees||32 degrees||28 degrees|
|Features||UHMW bearing cups, hardened, chrome-plated ball, adjustable preload, greasable,||All metal, PTFE lined, self-lubricating bearing, non-greasable, no preload adjustment, no special tool required||Stainless steel pre-load ring with locking screw, grease nipple, composite bearing cups. Available in left and right hand thread. Left & right hand jam nuts and tubing inserts available.|
RE Large Bearing
|A great low-cost option, the large RE bearing is a good all-round joint. It uses a chrome-plated ball with integrated spacers, replaceable Delrin bearing cups, and a threaded ring that can be used to set and adjust pre-load on the ball. They are greasable via a supplied grease nipple and rebuildable. Being quite common, individual parts are available from many locations. A special tool is required to build and adjust the joints, but costs only a few bucks. As supplied, they offer no adjustability for link length, but one could weld some threaded rod to the joint and create and adjustable joint.|
|The RE joints are designed to be welded directly to the notched end of your link. Due to the width of the cartridge, or body, of the joint there is a practical limit to the OD of the tube you can use with them. Much wider than 2” OD tubing and you will have problems getting a satisfactory weld without gaps between the tube and the joint. The pic at left shows a large RE joint being test-fitted to a 2" OD tube. When using tube with an OD approaching the limit, be aware that you will be welding to the outside of the threaded area of the joint body. Care is required to avoid warping the internal threads, and I recommend you thread the adjustable ring into the body when welding to the tube. The quality of the plated ball does not approach that of the other two joints I evaluated, but the cost is quite a bit lower. The joint uses a decent-sized 9/16” bolt.|
Poly Performance Uniball
A relatively new offering from one of my favourite suppliers in the industry, Dave at Poly Performance had the Uniball created with performance in mind. This joint is designed for those seeking a tight, maintenance free, extremely high quality joint with maximum misalignment capabilities. It uses a high-quality, precision, FK spherical bearing and trick custom-machined misalignment spacers held in a tubular cartridge body much like the RE bearing. However, the FK bearing has neither provision for lubrication nor pre-load adjustment as it is PTFE lined and factory-set. This means that because the FK bearing is a self-lubricating precision assembly, pre-load adjustment and lubrication are not required, either during initial assembly or throughout the life of the joint. In most cases this is an advantage: you need not guess at an appropriate pre-load setting - the bearing is already set for maximum strength and durability - and periodic re-greasing isn't required. However, some users may feel more comfortable with a joint they can adjust and grease as required. The catch is - you have to actually do it. Much like the age-old argument surrounding sealed vs. greasable U-joints - the greasable joint is only advantage to those who religiously do so. If you're inclined to neglect maintenance from time to time, you're probably much better off with a self-lubricating, factory-set joint like the Uniball.
The Poly Performance Uniballs are a high-end joint that combine the best features of traditional high-quality Heim joints (precision, maintenance-free bearings) with the benefits of a cartridge joint (ease of use - just weld to tube and go. Rebuildability - the FK bearing can be replaced without having to fabricate a whole new link). Mix in the trick missalignment spacers and you have a unique and compact joint.
Compact, strong, precise, and capable of wicked articulation this joint is an excellent choice for top-end buggies and other rigs seeking maintenance-free high-end performance.
Evolution Rebuildable Heim
The monstrous rebuildable Heim joint from newcomers Evolution Machining and Fabrication is the king of size and brute strength. Because they are custom made specifically for use in link suspensions, the Evolution joints have several very attractive features. Custom machined from chrom-moly and stainless steel these brutes are greasable, rebuildable, and feature adjustable pre-load. They are also designed to use a large but reasonable ¾” bolt, which is a very nice feature in a joint of this size – often a very large joint requires the use of a 1” or larger bolt which can make bracket fabrication and sourcing the bolts difficult.
They come supplied with a special spanner for adjusting the pre-load ring, as well as with two half-inch wide DOM spacers to be placed either side of the ball to achieve misalignment. One advantage of this is that, because the spacers are simply 3/4" ID DOM tube, should they be too long or too short, you can fairly easily make your own.
If you look carefully at the joint in the right of this picture you can see the hex socket set-screw that keeps the preload ring tight.
The Evolution Joints come in both left- and right-hand thread, as do the accompanying jam nuts and weld-in threaded tube adapters. One nice thing about using a joint with a threaded shank is that making the links is extremely easy, since all you need to do is cut the tube to length, drop in the tube insert, and weld. The pic at right shows an Evolution tube adapter inserted into a 2-1/4” x ¼” 1026 DOM tube. The tube adapters come with a generous bevel, allowing for a good, strong weld joint. Another advantage to this style joint is the fact that the joints themselves are completely removable from the link so that, should you damage a link beyond repair, you can remove the joint and jam nut, simply buying a new tube and insert to make the new link.
Evolution can also supply the threaded inserts in either mild-steel (for use in DOM) or in chrom-moly for those using chrom-moly tubing for their links. This is an excellent option as welding a mild steel insert or cartridge joint body to a chrom-moly tube defeats the purpose of using chrom-moly in the first place.
The boys from Evolution have a long history of building and abusing hardcore rigs, and it's clear their experience has gone into these joints.
The Evolution joints are truly impressive, offering first-rate machining, from the joint itself to the accompanying tube inserts and jam nuts - all fully custom made, in-house, with one goal in mind - to be the biggest, baddest, toughest joint available. I noted that the thread-forms on the joint's shanks and in the jam nuts and inserts were excellent.
It's hard to fully appreciate the truly massive size of these joints without holding one in your hand, but the pic at left should give you some indication. Because of the massive size of these joints, including the 1-1/4” threaded shanks, there are a limited number of options for the size of tube you can use. The threaded tube inserts take a tube with a 1.75” inside diameter. The following table gives some options for this size tube.
For my links using the Evolution joint I chose 2-1/4” x ¼” 1026 DOM. The pic at right shows one end of a completed link next to a standard 3/4" Heim joint. Interestingly, this tube is both lighter and stronger than the 2” x 3/8” tube I used with the other joints. The only drawback is size – a 2-1/4” OD tube is a big tube, and you need quite a bit of clearance to use it.
I was extremely impressed and pleased with the quality of the Evolution joints – they are perfect for use in the top link of my front-end 3-link where I need maximum strength and durability to withstand the loads a single top-link sees from counteracting axle wrap; and their adjustability makes setting and adjusting pinion angles a snap. If you need adjustability combined with unmatched strength, and have the space, these are the joints to use.
All three of these joints have their strengths and weaknesses, and their appropriate applications. Looking for a low-cost all-round joint that will perform well and not break the bank? - then the RE bearing is your choice. Have a big, hardcore rig you love to abuse and afraid that plastic inserts and 9/16" mounting bolts won't stand up? If it's the ultimate in adjustable brute strength you need - Evolution is the way to go. Have a smaller or high-performance buggy that needs super-tight, trouble free, max performance suspension links and/or just have to have the bling - look to Poly Performance's trick Uniball joints.
In my own rig I used a combination of all three joints as follows:
For my front lower links I used fixed length links with an RE bearing at each end for the following reasons:
For my front upper link I used two Evolution joints and 2-1/4” x ¼” tube because:
For my rear links I chose a mix of Poly Performance Uniballs and Evolution Joints as follows:
Whatever your particular needs may be, or whatever your design may call for, I'm certain that one of these joints can fill the need. Also, both Poly and Evolution are top-notch professional companies to deal with and I can highly recommend them both.
Bearings & Poly Performance Uniballs:
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