i_r_beej
Well-Known Member
- Messages
- 993
The larger tired on the AMP cars easily overpower the stock servo saver in the AMP truck and buggy. I've gotten tired with the really vague steering (I've been spoiled by my Boost buggy's RPM steering assembly and MG servo) so I decided that I would try something to improve the steering while still offering more protection to the servo. Without buying a new servo.
I'd read about the Associated B4/T4 steering assembly being virtually identical to the ECX assembly (or is that the other way around?) and figured that would be the ideal solution for my scenario.
First off, you can't just buy an Associated steering assembly. You must buy the plastic parts, the servo saver sprint and nut, and maybe some other junk. (Do I already sound grumpy?)
Instead I scoured Ebay for a complete assembly, removed from a built car. What luck! I found one, complete with top-plate, servo horns, and a bag of SAE screws (Curse you, Associated! Think metric!).
Here's a photo of the AE and ECX assemblies, side-by-side:
As you can see the two ARE quite similar. The Associated assembly incorporates a servo saver via a split shaft that's adjusted by the nut and compression spring. Adjustability is nice! Okay, let's get this thing into the AMP!
Wait a sec... is the Associated steering rack a little shorter than the ECX component?
Yes. Yes it is. Fortunately it's only a millimeter or two so probably won't make much of a difference to the AMP's handling. Maybe. Probably? Okay, I don't want to buy turnbuckles (actually I do, but I won't) so I'll just swap out the steering rack for the ECX component.
Um... WHAT ARE THESE?
Okay, so it's not a direct fit. I can drill out the ECX rack easy and install the Associated bushings. That's why this is called a "hobby," right?
I used a 5/32" drill bit to enlarged the holes in the ECX rack allow the fitting of the Associated bushings. Once this modification was complete, the ECX steering rack attached to the Associated bellcranks with no fuss. Now to attach this to the AMP's top-plate. Aw, c'mon! Now what? There's a gap! I need a spacer! Washers?
Fortunately I can take the two larger washers present in the ECX assembly and stack them to fill that gap. Here you can seem them stacked on the screw. These two washers are an almost perfect fit and allow the Associated steering to mount without any alignment issues.
On the non-servo saver bellcrank, I use the ECX self-tapping screw from the stock steering assembly. I use the Associated screw to mount the servo-saver bellcrank to the ECX top plate. However, there is yet another wrinkle: I need a nut! In the ECX assembly, a machine screw threads down from the top into an aluminum bushing. In the Associated assembly, a 1.125" 6-32 screw slides up from the bottom. And that's where the problem lies: How to secure it to the ECX top-plate? With more hardware! A Du-Bro 6-32 nut just barely engaged with enough threads to hold everything together. Unfortunately, the Associated assembly completely binds up under any pressure so I can't actually tighten the nut down. I turn it to eliminate any wobble and then secure it with some blue thread-locker. Even so, there is small amount of noticeable friction, but I apply some Finishline fluoro oil to the pivots and this helps a little. Nothing that the stock steering servo can't handle.
So now everything is in place and it's time to reassemble the AMP. A quick bench test confirms that everything seems to work like it should.
The next day was rainy so I took the AMP to the local indoor track to test it. I think this was actually a good test: a high-traction surface with plenty of unforgiving bumps and jumps. If the transplanted Associated steering assembly is going to come loose, it should do it here.
After a couple of hours of driving (some at the hands of an inexperienced 11 year-old) the steering assembly was still working smoothly, nothing seemed to have worked its way loose. Unfortunately the reverse shimmy is still present, although greatly reduced.
In the final analysis I don't think I could recommend the Associated B4/T4 steering rack as an "upgrade." It does have much less side-to-side play than the stock ECX steering assembly, and the reverse shimmy is also reduced, but it doesn't really eliminate play like the RPM upgrade. On carpet, the AMP did understeer a little on high-speed turns but in the dirt it will likely perform just fine and any steering issues will likely be due to ground/tire interface. I just have concerns about the long-term durability of this modification since it's a bit of a kludge.
RPM did us all a favor by going to the trouble of designing and manufacturing a fabulous upgrade part in the ECX steering servo eliminator. It works fantastically well in my ECX Boost and I plan to eventually install one in the AMP along with a decent (and inexpensive) metal-geared servo and let the plastic servo horn serve as a sacrificial part in the event of a big hit to the front wheels.
So, I highly recommend installing the RPM ECX steering assembly and a metal-geared steering servo. As demonstrated in my Boost, it's a rock-solid combination and a definite upgrade to performance. And the AMP is such a blast to drive, it's totally worth that investment.
I'd read about the Associated B4/T4 steering assembly being virtually identical to the ECX assembly (or is that the other way around?) and figured that would be the ideal solution for my scenario.
First off, you can't just buy an Associated steering assembly. You must buy the plastic parts, the servo saver sprint and nut, and maybe some other junk. (Do I already sound grumpy?)
Instead I scoured Ebay for a complete assembly, removed from a built car. What luck! I found one, complete with top-plate, servo horns, and a bag of SAE screws (Curse you, Associated! Think metric!).
Here's a photo of the AE and ECX assemblies, side-by-side:
As you can see the two ARE quite similar. The Associated assembly incorporates a servo saver via a split shaft that's adjusted by the nut and compression spring. Adjustability is nice! Okay, let's get this thing into the AMP!
Wait a sec... is the Associated steering rack a little shorter than the ECX component?
Yes. Yes it is. Fortunately it's only a millimeter or two so probably won't make much of a difference to the AMP's handling. Maybe. Probably? Okay, I don't want to buy turnbuckles (actually I do, but I won't) so I'll just swap out the steering rack for the ECX component.
Um... WHAT ARE THESE?
Okay, so it's not a direct fit. I can drill out the ECX rack easy and install the Associated bushings. That's why this is called a "hobby," right?
I used a 5/32" drill bit to enlarged the holes in the ECX rack allow the fitting of the Associated bushings. Once this modification was complete, the ECX steering rack attached to the Associated bellcranks with no fuss. Now to attach this to the AMP's top-plate. Aw, c'mon! Now what? There's a gap! I need a spacer! Washers?
Fortunately I can take the two larger washers present in the ECX assembly and stack them to fill that gap. Here you can seem them stacked on the screw. These two washers are an almost perfect fit and allow the Associated steering to mount without any alignment issues.
On the non-servo saver bellcrank, I use the ECX self-tapping screw from the stock steering assembly. I use the Associated screw to mount the servo-saver bellcrank to the ECX top plate. However, there is yet another wrinkle: I need a nut! In the ECX assembly, a machine screw threads down from the top into an aluminum bushing. In the Associated assembly, a 1.125" 6-32 screw slides up from the bottom. And that's where the problem lies: How to secure it to the ECX top-plate? With more hardware! A Du-Bro 6-32 nut just barely engaged with enough threads to hold everything together. Unfortunately, the Associated assembly completely binds up under any pressure so I can't actually tighten the nut down. I turn it to eliminate any wobble and then secure it with some blue thread-locker. Even so, there is small amount of noticeable friction, but I apply some Finishline fluoro oil to the pivots and this helps a little. Nothing that the stock steering servo can't handle.
So now everything is in place and it's time to reassemble the AMP. A quick bench test confirms that everything seems to work like it should.
The next day was rainy so I took the AMP to the local indoor track to test it. I think this was actually a good test: a high-traction surface with plenty of unforgiving bumps and jumps. If the transplanted Associated steering assembly is going to come loose, it should do it here.
After a couple of hours of driving (some at the hands of an inexperienced 11 year-old) the steering assembly was still working smoothly, nothing seemed to have worked its way loose. Unfortunately the reverse shimmy is still present, although greatly reduced.
In the final analysis I don't think I could recommend the Associated B4/T4 steering rack as an "upgrade." It does have much less side-to-side play than the stock ECX steering assembly, and the reverse shimmy is also reduced, but it doesn't really eliminate play like the RPM upgrade. On carpet, the AMP did understeer a little on high-speed turns but in the dirt it will likely perform just fine and any steering issues will likely be due to ground/tire interface. I just have concerns about the long-term durability of this modification since it's a bit of a kludge.
RPM did us all a favor by going to the trouble of designing and manufacturing a fabulous upgrade part in the ECX steering servo eliminator. It works fantastically well in my ECX Boost and I plan to eventually install one in the AMP along with a decent (and inexpensive) metal-geared servo and let the plastic servo horn serve as a sacrificial part in the event of a big hit to the front wheels.
So, I highly recommend installing the RPM ECX steering assembly and a metal-geared steering servo. As demonstrated in my Boost, it's a rock-solid combination and a definite upgrade to performance. And the AMP is such a blast to drive, it's totally worth that investment.
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