ECX Boost RPM steering upgrades

i_r_beej

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As part of my quest to create a Boost that's not just race-ready, but race-worthy, I've begun a series of upgrades featuring RPM's excellent after-market replacement parts.

First up is the "RPM Servo Saver Eliminator Bellcrank." The set ships with Delrin bushings that are a good, close fit and provide a smooth actuation by the bellcrank. The bushings can be easily replaced with cartridge bearings that provide a tiny, tiny improvement over the plastic bushings. The true benefit of a cartridge bearing supported bellcrank system will be in long-term durability, although the bellcrank and bearings will very likely outlast the rest of the car. However, the bearings are relatively inexpensive and what's the point of a hobby like this if you can't turn things up to 11, right? That said I don't think I can realistically recommend the addition of cartridge bearings to the RPM Servo Saver Eliminator Bellcrank; it works very well in its stock form!

The bellcrank system is a direct replacement and utilizes some parts from the stock ECX equipment, so disassemble with care! In the photo below, you'll need the small cross-brace and black washers, plus mounting screws.

It's easy to overlook just how much play a relatively loose servo saver can introduce in a steering system. By eliminating the servo saver completely, the RPM bellcrank creates much more positive steering without the "hesitation" created by the spring mechanism as it opens and (almost) closes during turning. The driving surface and tire tread and make this worse so the RPM Servo Saver Eliminator Bellcrank is a completely worthwhile upgrade.

rpm-steering-bellcrank.jpg

As part of the steering upgrade, and with no servo saver, I installed a Turnigy 1258TG titanium-geared steering servo. This servo is a rebranded PowerHD 8309TG and a direct competitor to the Savox 1258TG. The Turnigy servo offers nearly identical or better performance when compared to the Savox 1258: its transit time is .10 second compared to .08 for the Savox and it runs significantly cooler (translation: its motor is more efficient), all for about half the price!

The only issue when installing is that the right-hand mount interfered with the wire exiting the servo's case. I had to cut and sand off about 2mm of material. An easy modification that did not adversely affect performance or subsequent fit.

turnigy1258tg-servo-ecx-boost.jpg
 
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After the steering bellcrank upgrade, I moved on to the RPM caster blocks and RPM front spindle blocks. These components removed a tremendous amount of play that was present in the stock setup. As you know, the stock steering knuckle can move up and down in the caster blocks. The RPM spindle blocks remove all of this vertical play. Together, the caster blocks and spindle blocks do much to reduce front-end play on the 2WD ECX vehicles. In the photo below I compare the stock assembly (left) to the RPM assembly (right). Actually the RPM components aren't bolted together, yet you can see that the spindle block hasn't tipped over due to it's close fit with the caster block. Despite being a close fit, there is no binding and little friction. I expect this to free up even more with use and normal "wear and tear."

rpm-front-caster-steering-comparison.jpg

In this next photo, I've placed the two assemblies side-by-side to get a better sense of just how much stronger looking the RPM components are compared to stock. Even with their burlier construction, there are no fitment issues and these are a "bolt on" upgrade. As an added bonus the the cartridge bearings are slightly larger than stock (11mm diameter vs. 10mm diameter) which RPM claims doubles load and fatigue ratings. As with the bellcrank assembly, I think these components will easily outlive the rest of the vehicle!

rpm-front-caster-steering-comparison2.jpg

After completing the installation I did notice that there seemed to be a little binding once the wheel nuts were tightened down. I'm not certain, but I attribute this to the rubber seals in the new bearings; the stock bearings only had metal shields. I believe that this will disappear once the lubrication in the bearings begins to "weep" past the seal's inner circumference.

Here is the stock steering assembly:

rpm-steering-oem-assy.jpg

And here is the RPM assembly:
rpm-steering-rpm-assy.jpg

I head to the track this weekend to put these new upgrades to the test. I anticipate that the steering system upgrades will enable the car to turn with nothing more than a thought! :)
 
Man look how much beefier those RPM parts look compared to stock. So happy RPM is cranking out hop-up parts for or ECX RC's.
 
After the steering bellcrank upgrade, I moved on to the RPM caster blocks and RPM front spindle blocks. These components removed a tremendous amount of play that was present in the stock setup. As you know, the stock steering knuckle can move up and down in the caster blocks. The RPM spindle blocks remove all of this vertical play. Together, the caster blocks and spindle blocks do much to reduce front-end play on the 2WD ECX vehicles. In the photo below I compare the stock assembly (left) to the RPM assembly (right). Actually the RPM components aren't bolted together, yet you can see that the spindle block hasn't tipped over due to it's close fit with the caster block. Despite being a close fit, there is no binding and little friction. I expect this to free up even more with use and normal "wear and tear."

View attachment 471

In this next photo, I've placed the two assemblies side-by-side to get a better sense of just how much stronger looking the RPM components are compared to stock. Even with their burlier construction, there are no fitment issues and these are a "bolt on" upgrade. As an added bonus the the cartridge bearings are slightly larger than stock (11mm diameter vs. 10mm diameter) which RPM claims doubles load and fatigue ratings. As with the bellcrank assembly, I think these components will easily outlive the rest of the vehicle!

View attachment 472

After completing the installation I did notice that there seemed to be a little binding once the wheel nuts were tightened down. I'm not certain, but I attribute this to the rubber seals in the new bearings; the stock bearings only had metal shields. I believe that this will disappear once the lubrication in the bearings begins to "weep" past the seal's inner circumference.

Here is the stock steering assembly:

View attachment 474

And here is the RPM assembly:
View attachment 475

I head to the track this weekend to put these new upgrades to the test. I anticipate that the steering system upgrades will enable the car to turn with nothing more than a thought! :)

Those caster blocks and spindle blocks look a whole lot nicer. Gonna have to put some on my amp buggy also.
 
So I have all of these rpm parts as well as the rear parts. Today I ripped the shoulder screws out of the front drivers side spindel block. Has anyone had this issue and came up with a fix
 
@mrc82 I noticed that when I was installing the RPM parts that screws seemed to thread into some of the mounting holes really easily.

After a few weeks and some hours of track time, I've discovered that the ECX ball studs I've mounted to the caster blocks and rear axle carriers (for camber links) manage to work themselves loose. I contacted RPM about this and they recommend the use of regular CA glue ("superglue") as a thread-locker. DON'T USE conventional thread-locker as they are not compatible with plastics and may deteriorate the plastics in the components.

I applied just a drop to the threads of the ball studs and this seemed to help prevent - but not eliminate - the studs working loose. However, I use some old glue so it may not be as effective as it should be.
 
I don't think those spindle blocks are intended to be a flexing part, are they? You could use a two part marine grade epoxy and it will never let go.
 

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