Shoulder screws coming out of the RPM caster block

MADitto

Well-Known Member
Messages
82
I have seen this issued mentioned in a few different post.

I am having the same problem. I have lost at least 3 shoulder screws.

Form what I can see the friction from the caster block on the screw is backing the screw out as you turn the wheels. I have tried a small out of gear grease, that helped it from binding but they still back out. If I tighten it too much it binds.

I was thinking of over boring the holes and putting in a small baring or if I can match the current hole diameter with a metal sleeve so I can use a standard fine thread screw and get deeper into the steering arm.

Does anyone have a better solution?
 

Smokestack

Member
Messages
15
Location
The Hammer, Canada
I've read here somewhere that RPM recommends using a drop of super glue as a thread locker, but I'll admit to being a little leery using such stuff on anything that may need to be removed intact. My solution was to use a bit of silicone as it dampens vibration, has enough stick to prevent backing out (so far, anyway!), and can be removed relatively easily. I've had no problems so far, and run my MT with silicone in all RPM parts (A-Arms and Steering Blocks) for about 5-6 three pack runs.
 

xlDooM

Well-Known Member
Messages
682
I lost both shoulder screws from the stock caster block yesterday. First I lost one, but the thing was still drivable, so...

I'm just going to glue them down hard when I get the new screws. The only reason I see them having to come out is when I've broken the caster block anyway?
 

i_r_beej

Well-Known Member
Messages
981
+1 on the super glue (cyanoacrylate). On my car, the ball studs were working their way out of their holes in the RPM spindle and axle holders. As a threadlock the superglue has worked quite well.

Simple, cheap, and effective.
 

i_r_beej

Well-Known Member
Messages
981
Holy cow! This is so weird. I've never had this problem before but just this last weekend at the track, the bottom shoulder screws worked their way out THREE TIMES. What? Definitely going to have to buy some extras to keep in the parts box. If that happened in a race I'd be done!
 

MADitto

Well-Known Member
Messages
82
I did use a very small amount of super glue, and it seems to be working.

One thing with buying the replacement shoulder screws is that they come in a package. 4 of the correct size and 4 others that don't work on the truck. It sucks when you have to buy a set when you only need part of it.
 

xlDooM

Well-Known Member
Messages
682
To be fair, the set is dirt cheap. I paid more in shipping than for the screws, so I can fully understand that for ECX the cost is in the packaging and not in which, or how many screws are in the bag. Having two fewer items in the shop must be a saving in itself (my package had 3 kinds of screws).
 

xlDooM

Well-Known Member
Messages
682
So today the shoulder screws popped out. Not worked loose, popped out. I crashed and the wheel was no longer on the vehicle. Both screws got ripped out of the caster block. More superglue ensued.

IMG_20160610_175627095.jpg
 

i_r_beej

Well-Known Member
Messages
981
Okay. This issue with the RPM front spindle blocks is now officially driving me crazy. My day at the track was just about ruined as I was having to replace the shoulder screw every few minutes. Fortunately I only actually lost one screw. I was able to track down the missing screw most times.

Super glue is no longer holding the screws in place. I think that the threads have actually been stripped in on spindle block.

I'm probably just going to have to go back to the stock spindle blocks! At least the shoulder screws threaded in TIGHTLY!

Any ideas for making this work? PTFE tape on the threads?
 

X

Conspiracy of One
Staff member
Supporting Member
Messages
1,140
Do you have enough room for something like a PEM nut/ threaded insert?

Something like this:

upload_2016-6-27_14-0-5.png

Or this:

41Ah9vjgXFL._AC_US160_.jpg
 

xlDooM

Well-Known Member
Messages
682
Lately every bashing session has ended with me trying to recover the shoulder screws. I only have one spare left right now. Since your RPM spindle block is equally affected as my stock one (only the left side... think they only work until the first nasty collision) I decided to go for another solution.

hrspindlepack.jpg
Hot Racing aluminium spindle blocks. From some other people's experience it seems HR aluminium is only slightly stronger than toasted bread, but I'm hoping the plastic steering links will pop off as per usual and keep the spindles alive. Here they are on the truck:
hrspindle.jpg
I'll let you know how it fares...
 

i_r_beej

Well-Known Member
Messages
981
Do you have enough room for something like a PEM nut/ threaded insert?
The threaded insert sounds like a promising solution. When I get back to the workbench I'm going to take a look and things and do some cost/benefit analysis. :)

I sent a message to RPM and they suggested the same thing:
Unfortunately, that is the most common problem we hear about and it's because of the stock ECX design of those shoulder bolts. Quite simply, they made the threads of that bolt too short. The same thing happens to stock steering knuckles quite often.
Since we don't build metal parts and we're limited on the design of that area of the spindle block because of the caster block, it's a section we couldn't "fix" from the stock design. Super glue is about the best and easiest option we've found so far to help keep them in place since super glue acts as a sort of thread locker in RPM nylons. However, if you've tried that and it doesn't work, you can try the next step. However, before I tell you what that is, I need to warn you that modifications made to RPM parts could potentially void the warranty. With that said, you may want to consider a brass insert for those threads. You'd simply drill out the screw hole to 4mm, then press in a brass insert to reacquire the 3mm thread size. The problem is, I don't know of any brass inserts short enough to work. Most of what we've found are a minimum of 4.8mm long, about 1 - 1.5mm too long. You can acquire some and see about shortening them to fit. If you do this, be sure to install the bearings before pressing in the insert but after drilling out the holes. That way the insert doesn't get pressed in too far to where they interfere with the bearing bores. Good luck!
 

X

Conspiracy of One
Staff member
Supporting Member
Messages
1,140
Just did a quick internet search for pictures. I'll look around and see if I can find an insert per the specs RPM gave you. Do you have the thread size for the stock screw?
 

i_r_beej

Well-Known Member
Messages
981
I'll have to check when I'm at home. Please don't spend any time doing the "leg work" to track down parts. I thought maybe it was something you had a link to. :)

I spent a little time researching and found out that Associated T4/B4 caster blocks and spindle blocks were a virtual direct fit onto the ECX 2WD A-arms. (Boost, in my case) The design appears to be better in that it has a kingpin that goes all the way through the caster block and spindle blocks. No shoulder screws. Soooo... I tracked down a complete front-end set on Ebay and ordered them.

The Associated spindle blocks use a trailing-axle design so that will be a little different from the ECX design. Apparently trailing axle steering is "less aggressive" than in-line (stock ECX 2WD setup) but easier to drive and more stable on high-grip surfaces. (Perfect! I'm racing on carpet!)

We'll see.
 
Last edited:

X

Conspiracy of One
Staff member
Supporting Member
Messages
1,140
I'll have to check when I'm at home. Please don't spend any time doing the "leg work" to track down parts. I thought maybe it was something you had a link to. :)

I spent a little time researching and found out that Associated T4/B4 caster blocks and spindle blocks were a virtual direct fit onto the ECX 2WD A-arms. (Boost, in my case) The design appears to be better in that it has a kingpin that goes all the way through the caster block and spindle blocks. No shoulder screws. Soooo... I tracked down a complete front-end set on Ebay and ordered them.

The Associated spindle blocks use a trailing-axle design so that will be a little different from the ECX design. Apparently trailing axle steering is "less aggressive" than in-line (stock ECX 2WD setup) but easier to drive and more stable on high-grip surfaces. (Perfect! I'm racing on carpet!)

We'll see.

Nice find, hopefully they work well!
 

K0N3R77

Well-Known Member
Messages
85
ive gone as far as drilling out my caster and spindle blocks and using self tappers (cut to length) just so I can use my car. But then I got rpm parts glued as soon as I put them on and same thing shoulder screws gone!! I also found that the stock screws barely made threads (this sucks). Now I have little bushings ( a little sloppy) traxxas screws and super glue haven't had it out yet but I'm a little doubtful. I really like your idea X I guess that's what I will try next unless i_r_beej is successful with the associated part. Could you post the part numbers i_r_beej wouldn't mind checking them out. Also thanks for all the research guys it's great to have all this help
 

AbdoSnowMan

Active Member
Messages
37
My son's Torment and a friend's Ruckus are doing the same thing. Before I saw this thread I thought I may have to buy a metal detector to find the screws every time they fall out. Watching for the outcome....
 

xlDooM

Well-Known Member
Messages
682
I was just looking at the Associated front setup, and you can get both trailing and inline axle versions of the axle carriers (spindle blocks). I don't know what else we will need for the inline version. At least the caster blocks and axle sets, possibly adjustable turnbuckles if the ball joints end up in different positions.

Let's just hope HR's aluminium version of the stock design holds up, then it's a simple $19 fix.
 
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