4Crawler Offroad Products

Idler Arm Upgrades

for 1986-1995 4WD 4Runner, Pickup, Hilux, Hilux Surf models

also fits T-100 4WD pickup models

Contents:

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Introduction:

If there was a "weak link" in the Toyota IFS pickups and 4Runners, that would be the steering system. You can see below that it is a fairly complicated system with lots of moving parts and joints. One of the most highly loaded components in that system is the idler arm and it's operation is described in the paragraph following. Folks often ask if cranking up torsion bars or installing ball joint spacers or adding this or that sort of lift will cause increased wear and tear on the steering and idler arm. Actually the short answer is not really, but the longer answer is it depends. One likely reason for installing the lift is that you may be considering taller and/or wider wheels and tires. And you may be considering the lift and larger tires in order to either go off-road or to handle more challenging off-road driving. And with the lift and larger tires and harder off-road driving you may end up doing, that will put more wear and tear on the steering. So did the lift cause the steering wear or not?

A typical Toyota 4WD IFS steering system is pictured below. The steering wheel and shaft connect to the steering box (8). The pitman arm (9) connects to the sector shaft (10) on the bottom of the steering box and transfers steering input to the center link or relay rod (6). The relay rod connects to the idler arm (3) on the passenger side. To the ends of the center link are tie rod ends (2 and 4/5) that connect to the steering knuckles on each side of the front axle to turn the wheels. A steering stabilizer (7) attaches between the frame and center link to dampen jolts from the road. Of all these parts, only the idler arm and steering box are re-buildable, but the idler arm seems to take the brunt of the abuse and is the most common part to require repair.

If you are tired of destroying stock plastic idler arm bushings, these bronze bushings are machined to exacting tolerances in order to provide maximum strength and life. They are very hard and durable. As a result, not only can they bear much more load and resist wear, but they also transmit much less shock to the steering wheel making the truck easier to handle on rough roads.

One way to look at the purpose of the bushings on the idler arm is to imagine holding up a flag on a pole. If you only use one hand to hold the flag pole, it puts a lot of stress on that one hand and it is hard to hold it straight. If you use two hands separated by a distance, the load is more equal between your two hands and you can hold it straight a lot easier. WIth the stock plastic bushings, you have the idler arm set up more like the one-handed setup, since the bottom bushing can give under load letting the idler arm twist inside the housing. Now with the two bronze bushings, the shaft is held solidly and the forces are transferred along the shaft to both bushings more equally. Now there is a limit to the ultimate bending strength of the steel shaft and if you put enough load on it, it'll bend no matter what sort of bushings you use. The bigger the shaft, the stronger it is, given similar material. So the bushings are designed to fit the largest diameter shaft available in aftermarket idler arms.

One consideration of a machined bronze bushing is the need for tight tolerances in order to fit over the shaft of the idler arm and inside the housing of the idler arm bracket. Unlike soft plastic that can be squished into a too-small hole, the bronze bushings require a precisely sized hole and shaft for a good fit. We measured numerous idler arms in search of the strongest and most affordable to support. Luckily for you, we found both in some commonly available idler arms:.

Frequently Asked Questions:

  1. Why just support those idler arms?
  2. Do these bushings work with the OEM/factory Toyota idler arm?
  3. What do I do if I bend my idler arm?
  4. Do I need a zerk fitting in my idler arm with the bronze bushings?
  5. How will my order be shipped and how long will it take to arrive?
  6. What options are available for right hand drive (RHD) applications?

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Why just support those idler arms?

Good question! There are two main reasons but before getting into them it is important to point out that 1st and 2nd gen idler arms are interchangeable. The second gen arms are typically stronger though. Therefore, if you have a 1st gen truck, it make sense to install a 2nd gen arm for the added strength.

First, the more affordable idler arms are also the best in terms of strength and mfg. quality. Initially we assumed that we would want to at the very least produce idler arm bushings for the high-end Napa arm as well as the OEM arm because we assumed they would be the best. After an idler arm spending spree we found some interesting things we'll discuss below.

Idler Arm Model Cost/US$ Shaft Dia. Shaft Dia. Supported
McQuay-Norris FA5040 $60 - $70 0.786" 20.0mm Yes
McQuay-Norris FA5040GL
for Right Hand Drive
$60 - $70 0.786" 20.0mm Yes
Duralast FA5040 $60 - $70 0.786" (some) 20.0mm Some *
Napa - Altrom/Ultra-8 ATM-1032403 $85 0.786" (some) 20.0mm Yes **
Duralast FA1739 ??? 0.786" - varies 20.0mm No
Moog K80536 $100 0.767" 19.5mm No
Napa - NCP2683702 $119 0.767" 19.5mm No
Beck Arnley 1014228 $125 - $150 0.767" 19.5mm No
Dealer/OEM $160 - $220 0.767" 19.5mm No
Sankei 555 $160+? 0.767"? 19.5mm No *
Napa - ATM-1032403 (sold for 2WD & 4WD) $71 0.703" 17.9mm No **

As you can see, the most affordable arms have the largest shaft diameter, and that larger diameter equates to about 5% increase in stiffness over the OEM part. Another interesting note is that the Napa 1032403 which has a diameter similar to a 2WD OEM arm is also sold for 4WD trucks even though from a strength standpoint, this arm is below spec., in fact it is about 25% weaker than the FA5040 arm.

The second reason to support one arm is cost and the desire to keep it down. The part of the shaft closest to the arm itself wears more than the rest. This means that a bushing that fits snuggly over the lower part of the shaft will not fit at all over the rest of the shaft. Assuming one was to verify that the shaft has a uniform diameter, there is the issue of calibration. My calipers might not measure out like yours. As a result it is difficult to machine the parts to order due to the tight tolerances in this application. To reduce part cost it is necessary to produce many at once and supporting one arm helps us accomplish this goal.

We entertained shipping idler arms in house to do custom bushings but the shipping to and from the customer is about equal the price of a pair of bushings. It costs much more to do one-off jobs so we would have to charge at least 2X the price for the bushings. Between the machine time and shipping, one could purchase the Duralast (FA5040) arm new, with warranty, and order a set of bushings for it.

Given these issues we have decided to support the most affordable yet strongest idler arm.

(*) And one thing to beware of is that sometimes, you'll get an arm marked "FA5040", but be sure to check for a "555" stamped on the idle arm itself (click here for a picture of the stamping). If so, that is likely a Sankei 555 arm, which is actually a smaller 2WD arm. If you find a "555" stamp, take that arm back and swap it for a genuine FA5040 arm. And you might want to be wary of on-line sellers, like on eBay, as you'll not be able to inspect the arm until it is shipped to you. If it is the incorrect part. you may be stuck with shipping it back for an exchange. Also, some Duralast FA5040 arms have a casting mark of "iak9424 L (click for picture of stamping)" instead of the plain "L" on the genuine FA5040 arm (click for picture of genuine FA5040 arm). This "iak9424 L" arm has an undersized shaft, comparable in diameter to the 2WD arm and appears to be a lower quality part. So be sure to check for that when you get the arm. Best bet is to pick one up at your local FLAPS where you can open the box at the counter and verify you are getting the genuine article before leaving the store. Note that some parts catalogs list a Duralast FA1739 arm for certain model years. This arm while the same overall dimensions as the FA5040 arm, has a lower quality casting and the arm shaft diameter is poorly machined meaning that it is difficult to get the bronze bushings onto it. So ignore the parts catalog recommendation and go with the FA5040 part. And this also applies to the Napa-ATM-103-2403 idler arm, if it has just the "L" casting mark, then it is likely the "good" version, otherwise, it is likely the undersized version.

So the bushings are built with an inside diameter (ID) of approx. 0.787" (~20mm) and an outside diameter (OD) of 0.941" (~23.9mm) to fit over the idler arm shaft and inside the idler arm housing.

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Do these bushings work with the OEM/factory Toyota idler arm?

As described above, no. This is one of those "rare" cases where the aftermarket parts are actually better than what the factory put on the truck. In idler arms, "bigger is better" and the aftermarket idler arm shafts are a bigger diameter than the OEM part, plain and simple. So if you have a factory arm and the plastic bushings are shot, your two choices are to pick up a replacement plastic bushing kit at the dealer or pick up one of the larger after market idler arms (above).

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What do I do if I bend my idler arm?

4Crawler Offroad does not warranty bushings damaged by bent idler arms, however, not to worry. If you bend an idler shaft and damage the flange of one of the bearings, you can simply remove the bushings reverse them placing the damaged flange bushing on top with flange loads are very small. If you bend another, rotate the bushing 180 degrees. At this point, if you bend another, you will need to purchase a new pair of bushings and hopefully and idler arm brace too. The good news is that hopefully your more expensive idler arm has been covered under warranty by your local auto parts store.

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Do I need a zerk fitting in my idler arm with the bronze bushings?

No, the bronze bushings are self lubricating. Grease will not hurt them so there is no need to wipe clean grease off of the housing and/or shaft but there is no need to install a zerk fitting if the idler arm does not have one.

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What options are available for right hand drive (RHD) applications?

There are currently 3 options for RHD applications. The first is to locally source an McQuay-Norris FA5040GL idler arm and then install the bronze bushings in that and install that idler arm on your vehicle. The second option is to make a hybrid idler arm, using your existing RHD idler arm bracket (i.e. the part that bolts to the frame) and a LHD McQuay-Norris FA5040 idler arm (using just the internal shaft and arm portion that is identical between LHD and RHD applications) then install the bronze bushings in your RHD bracket and install the LHD shaft and arm into that. In order for that to work, you need to check that the inner diameter (ID) of the bushing holes in your bracket match the outer diameter (OD) of the bronze bushings, that being 0.952" or 24.2mm. The third option is that we have heard from a few RHD customers, that they were able to get a suitable fit of the bronze bushings with their OEM idler arm, perhaps with a little sanding or filing to get the bronze bushings to fit inside the OEM idler arm housing.

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On-line Ordering:

We offer 3 options for your idler arm needs. If you have an existing, compatible idler arm, you can order the bronze bushings below. If you need a new idler arm and want to get one that will work with the bronze bushings, you can order a new FA5040 idler arm below. And if you want the new idler arm with a set of bronze bushings for later upgrade, you can order the full set below.

For shipping times and methods, see below.

The idler arm bushing kit is US$29.00/ea. plus shipping - In stock

Idler Arm Bushings Idler Arm Bushings Idler Arm Bushings

Idler Arm Bushings
+ $4.00 for uninsured US First Class Mail
Idler Arm Bushings
+ $8.00 for insured US Priority Mail
Idler Arm Bushings
+ $24.00 for uninsured International Priority Mail

New FA5040 Idler Arms: OUT OF STOCK

We have had problems with obtaining genuine FA5040 idler arms now with two suppliers, so until we locate a reliable supplier, we will not be able to supply idler arms.

If you are in need of a new idler arm that is compatible with the bronze bushings (above), you can usually find the FA5040 idler arm fat many auto parts stores, AutoZone is one, but there are many other suppliers. Just be sure to check the arm you purchase prior to leaving the store to make sure it is the genuine article.

Idler Arm - US Priority Mail
+ US$14.00 postage
Idler Arm - Canada/Mexico shipping
+ US$41.00 for Priority Mail
Idler Arm - International shipping
+ US$61.00 for Priority Mail


Idler Arm Plus Bushings (if bushings and idler arm above listed In Stock, then the combination is In-Stock) - OUT OF STOCK:

We have had problems with obtaining genuine FA5040 idler arms now with two suppliers, so until we locate a reliable supplier, we will not be able to supply idler arms.

If you are in need of a new idler arm that is compatible with the bronze bushings (above), you can usually find the FA5040 idler arm fat many auto parts stores, AutoZone is one, but there are many other suppliers. Just be sure to check the arm you purchase prior to leaving the store to make sure it is the genuine article.

Idler Arm+Bushings - US Priority shipping
+ US$14.00 postage
Idler Arm+Bushings - Canada/Mexico shipping
+ US$41.00 postage
Idler Arm+Bushings - International shipping
+ US$61.00 postage


Shipping times:

Be sure to supply an address that accepts US Post Office mail deliveries and be sure the address is valid.

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Visitor # 16139 since 15.DEC.2010

[Last updated: 20.November.2014]