Play in RCM Losi 8ight mount - RC-Monster Forums

ptt81 · 02:16 PM

Hey guys, I need some help. I bought the RCM motor mount to convert my new 8ight 2.0 Race roller but after install I noticed some play in the center diff, i.e. I can move it slightly back and forth (approx. 1.0~1.2mm of play), is this normal at all? what can I do to fix this?

I also noticed the center shafts angle up a bit and the "front center" shaft end dog-bone or whatever you call it sits nearly at the opening of the center diff drive cup, is this safe to drive? if not, whats the solution?

Anyone had done a conversion from a 8ight 2.0 race roller can help out? I'd appreciate it. Thanks

reno911 · 05.20.2010, 02:27 PM

Shims should fix that.

As long as there is no binding I would say the angle is fine. I think Mike has some longer drive cups if the dogbone doesn't sit right.

bryan · 02:48 PM

Everything you are mentioning is probrably the same with the factory mount "other than the height wich is not a problem".If you do decide to shim it make sure to put the shims so they move the diff. forwards.

ptt81 · 05.20.2010, 03:23 PM

ok so what are shims? where can I get some that would fit on this diff? where to put the shims? does it go between the flange bearing and the diff?

ptt81 · 05.20.2010, 03:28 PM

Quote:

Originally Posted by reno911

Shims should fix that.

As long as there is no binding I would say the angle is fine. I think Mike has some longer drive cups if the dogbone doesn't sit right.

Can you link me to the longer drive cup? i can't find it on there. thanks

brushlessboy16 · 05.20.2010, 03:57 PM

Quote:

Originally Posted by ptt81

Can you link me to the longer drive cup? i can't find it on there. thanks

Hello PTT81,

The driveshaft angle is fine, I have 2 8ights that have the same occurance. race them every weekend and never have thrown a front driveshaft. It will be alright.

Shim are more or less high precision spacers. very thin metal donuts that fill the space where the diff moves. They go in between the bearing and the differential mounts.

Your plastic front diff mount may be worn. My cars do not have any play in that department. I wouldnt worry about it to be honest

ptt81 · 05.20.2010, 04:09 PM

Quote:

Originally Posted by brushlessboy16

Hello PTT81,

The driveshaft angle is fine, I have 2 8ights that have the same occurance. race them every weekend and never have thrown a front driveshaft. It will be alright.

Shim are more or less high precision spacers. very thin metal donuts that fill the space where the diff moves. They go in between the bearing and the differential mounts.

Your plastic front diff mount may be worn. My cars do not have any play in that department. I wouldnt worry about it to be honest

do you know where I can get the shims that would fit the 8ight diff? I found two in the bag that looks like shims to me, not sure if these are the ones. Also my buggy is brand new out of the box so there is no worn. I think the play is because of the RCM motor mount, the stock plastic mount has no play.

ptt81 · 05:50 PM

So I tried the two shims I mentioned above that came with the kit and put them between RCM mount and the diff. bearing, the play is gone now, is this the correct way to do this? is this what the guys mentioned above? i just wanted to be sure I don't want to run something wrongly setup.

This is the one:
http://www.amainhobbies.com/product_...Shims-8ight-20

reno911 · 05.20.2010, 07:48 PM

Shims aren't going to hurt your setup unless it binds something. I can't think of many ways to mess that up so your probably fine. Just make sure to put the shims on the back side of the diff, that way it will push the slop towards the front where you say the dogbone is not close to the cup.

ptt81 · 05.20.2010, 10:26 PM

Quote:

Originally Posted by reno911

Shims aren't going to hurt your setup unless it binds something. I can't think of many ways to mess that up so your probably fine. Just make sure to put the shims on the back side of the diff, that way it will push the slop towards the front where you say the dogbone is not close to the cup.

thats what I did, it helped a bit, i'll post some pics later when I get a chance

ptt81 · 05.20.2010, 11:07 PM

I just noticed this ratcheting sound coming from the rear diff, is this normal? I hope someone know about this before I take it apart and try to fix something that may not be a problem at all. There is no binding at all, everything is smooth apart from the sound.

Before you say anything, again this is a brand new buggy and I have not mess with anything from the front or rear. I can confirm this is not coming from the center diff because I already try taking it off and the sound is still there.

Here is a vid showing the ratchet sound.

http://www.youtube.com/watch?v=taAC8r-AnRc

BrianG · 05.20.2010, 11:38 PM

That just sounds like the ring/pinion gears on the rear diff. Sounds normal to me as long as it doesn't bind. If it didn't make that sound, the shimming inside the diff could be too loose. The only setups I have that don't make that sound are the ones with helical cut gears.

ptt81 · 05.21.2010, 12:09 AM

Quote:

Originally Posted by BrianG

That just sounds like the ring/pinion gears on the rear diff. Sounds normal to me as long as it doesn't bind. If it didn't make that sound, the shimming inside the diff could be too loose. The only setups I have that don't make that sound are the ones with helical cut gears.

Whew! thought I got a bad kit or something. It doesn't bind at all, I can roll it freely by pushing it on the ground and it rolls a couple fts. So I should be fine moving to the next step? mounting electronics, etc.

Also I want to use the stock 48T metal spur, what pinion should I use? for 4S setup and CC 2200kv motor. I was gonna use the 45T plastic spur but its too wide and rubs on either RCM mount or stock mount, so metal spur is my only option and since i got the stock one, i don't want to waste it.

brushlessboy16 · 05.21.2010, 12:28 AM

2200 is wayy too much motor for a buggy, I have tried that setup lol

start with a 14t pinion and gear from there

ptt81 · 05.21.2010, 12:35 AM

Quote:

Originally Posted by brushlessboy16

2200 is wayy too much motor for a buggy, I have tried that setup lol

start with a 14t pinion and gear from there

well i bought the motor new a while back so I want to use it instead of buying another motor. I also heard that the smaller CC 2650kv run hotter than 2200kv, any thought on that? What's wrong with using the 2200kv in this buggy?