How2 - Plastic spur on crt .5 center diff

[Gee]

Kyosho D series 4wd Center Differntial - Motor Mount - Bearing ?
http://www.rc-monster.com/forum/showthread.php?t=17911
HB GT10 / LS10 Mods Upgrades Alternate Parts
http://www.rc-monster.com/forum/showthread.php?t=15263
DST Conversion thread PICS.
http://www.rc-monster.com/forum/showthread.php?t=17258
Kyosho Plaastic Spur Gears
http://www.rc-monster.com/gears.php?pg=2

I use the crt .5 center differential in my LS10.
I've been wanted to quite the little guy down since I put the center diff on it. With a little help while I was trying to get the RCM mount and a DST to work. Lincpimp told be where to go, but he inadvertently helped me out in the process. It sent me down the right path and next thing I had all my center differentials removed to get something figured out. This will work with the plastic spurs from Kyosho in the gears link above. This is actually a fairly easy mod and similar to what I did to get the Kyosho D series center differential to work with the RCM motor mount. It could be used on any other center differential for this scale.

I needed to do some shimming in order to get it to work with the RCM LS10 mount. I don't have a crt .5 but if it uses the same bearing (10x15x4mm) for the mount this will work. If it is a different size this should at least give you some idea as to what needs to be done to make it work for you. This isn't a drop in mod and you may require more or less messing around with yours to get the spacing right between the spur and motor mount. Here's to a quiter neighborhood.










This is were I started falling asleep at the keyboad last night while adding comments to the pictures. Notice how the comments were written. In my prime I could type and sleep for 8hr a day.

[BrianG]

Cool. I knew it was possible because I had done it before. But as you say, the diff dimensions change, and unless you want to mod something, it can't be a drop-in replacement (esp in the CRT.5).

[lincpimp]

Looks good Guy. I had a feeling that I could steer you in the correct direction...

Have you had success with the dst? Maybe I missed the thread?

[Gee]

Thank you two. I read Brians thread about the gear a while ago. Really suprised he gave up so easy. Afrer I caught on to your riddle of hints Linc it all started to come together. I mean couldn't you have been a little more blunt as to what you had in mind.

You probably seen the post about the dst by now.


Any of you crt .5 owners feel like doing something nice for a fellow RCMer and give me a link to the center differential cup to buy for the crt .5. I have downloaded the exploded view and there is no part number listed for it. I have seached several online store and have only found the front/rear cups. They make no reference as to those being used for the center differential. If they are used for the center then no link will be needed. I can find those again. Thanks. You might have noticed in the pictures mine is not holding the screws very well any more.

[BrianG]

Originally Posted by Gee

I read Brians thread about the gear a while ago. Really suprised he gave up so easy.

I gave up because it became clear that extending the CD mounting and replacing the shafts with slightly shorter ones would be needed to compensate for the extra CD thickness. Moot point though as the steel spur works perfectly fine, if a bit loud.

[GO-RIDE.com]

Originally Posted by Gee

Any of you crt .5 owners feel like doing something nice for a fellow RCMer and give me a link to the center differential cup to buy for the crt .5. I have downloaded the exploded view and there is no part number listed for it. I have seached several online store and have only found the front/rear cups. They make no reference as to those being used for the center differential. If they are used for the center then no link will be needed. I can find those again. Thanks. You might have noticed in the pictures mine is not holding the screws very well any more.

Gee,

Nice work with the center diff. I to have been wanting to get a plastic spur on the two crt.5s I have. Ever since I built up an E-8ight with the plastic spur I've been having a hard time accepting the noise of the .5 with steel on steel.

I'm pretty sure the crt.5 uses the same diff case on all three diffs. However, I think your screws are backing out because the hole pattern on the .5 diff case is not the same as the kyosho spur. Take a close look and you will notice they are spaced a bit different. To really get it right would require drilling (very precisely) and countersinking 4 new mount holes in the spur and using some epoxy to glue the old holes shut.

Another option might be to ovalize the exising holes in the kyosho spur. Install the spur and fill the gaps with epoxy. That would probably be easy, but require a new glue job each time you refilled the diff.

[Gee]

NO offense intended I was joking around with you guys. If it would of been of more importance or something needed we needed to be able to run something. We know you would have done what was needed. But the whole mod is moot point with the crt spur working fine. I don't know how many times in this hobby I've thrown my hands up in the air at moot point mods and just walked away. Then for some reason a month or 6 months later. I look at the same thing and bam. The answer is or was right there the whole time.

[BrianG]

No offense taken, just clafifying.

Sometimes, when you look at a problem, you overthink it and the solution is usually much simpler than you would have thought. For me, the amount of mods and custom parts (things I cannot rebuild if they break) was too much to justify the results.

[Gee]

Thanks. I will order the front/rear for the crt and use it for the center cup.

I had the problem prior to this mod with the screws. The holes in the differential were stripped and the screw couldn't be tightened down. Even with a longer screw they would just turn and not hold in the cup. Is that the same problem you had when you did the mod?

The other option to run the plastic spur is not perfect either but will work if done correctly.

[Gee]

Go-Ride.com - I misread your post, I see now that you feel the holes may not align up correctly and that you feel that might be another reason for concern. I thought that you also expereinced the screws backing out when you tried this mod. I understand it is a theroy you have as to what might be a contributing factor or a place for concern for the mod. A-main also confirmed the use of the front back cup for the center. I have ordered new cups and will take a closer look as to what your thoughts are and concerns about the mod. Sorry for the misunderstanding on my part. Will let you know what I find after the new parts arrive and I put it together again. Thanks for the input and the help.

[GO-RIDE.com]

No problem Gee. I have an extra Kyosho 46T spur and hope to work on mounting it on my crt.5 this weekend. If I make any progress I'll post my findings.

Very nice tutorial and write up...you "Gee-Man!!" This fellow crt.5 owner is glad to see it. Hope you guys work out the little stuff and this works out. Good stuff!!

[Gee]

I got a new crt .5 center differential in the other day. The holes are a little off but not a whole bunch. I think the problem I had was the size of screws that I had used were 3mm. The center differential takes the 2.5 screws. My diffs holes were stripped out so one wasn't even grabbing and the other was on the brink of being totally stripped also. Here's a couple shots of the new center cup with the plastic spur. This one might look a little different. Doing some more experimenting on using a stronger rear center dog bone. This diff has a Losi 8B cup installed for the centers rear cup. Only one I had to experiement with. I also increased the bearing hole in my RCM LS10 mount to fit at 12mm bearing. The red showing in the lower left hand hole on the diff is just a piece of the paper gasket.







The right size screws should help a lot and the new cup.