Jrx Pro: Slipper Too Loose?

[kfeldt]

I guess I don't have a question here, but I'll give you the story...

I've been running my Jrx Pro for the past month or so without a slipper clutch. I had an old Losi one, but decided when I got it back out that I didn't want to mess with it. After reading here how they can protect your trans, I decided to put mine back in. I'd driven it a couple times on some hot days with the slipper (let's pretend the ambient temperature was the problem ) and hadn't noticed any problems. So far, so good.

Tonight, I took the trans apart to put in new bearings (I still had the original ones in there). After I put everything back together, I noticed that the spur gear had some serious wobble to it when I turned the trans by hand. I was quite sure I would have noticed that before. I took everything back apart, and this is what I found...





I'm pretty sure that the input shaft hole didn't used to be that big, and I'm pretty sure that it used to be round. In person, it's pretty clear that the hole has a definite melted look to it. I'm thinking that it's opened up to the point where it isn't supporting that bearing well anymore, and that's what's causing my gear runout. My best guess is that I was running the slipper too loose and put enough heat into the hub to melt the trans case...

- Keith

[THUNDERSTRIKE1]

I THINK ITS JB WELD OR LOCTITE EPOXY I USED to fix one i restored.It was in a sirenge type thing that squirts both halves of epoxy onto surface
to be mixed on then apply and redrill the hole.Then smooth the surfaces.Getn hard to find those cases.DON

[minreg]

Never saw that before. Seems if the slipper was loose you would of been able to tell.
Where were you running it? There is no other damage?
Could the shaft be bent?

[kfeldt]

I have another trans case from my parts car. I hate to use it, but there's no way I can drive the car like it is...

I was running the car on my typical dirt track the last few times I drove it. I didn't notice anything unusual. That's the only part that bothers me... it seems like if the slipper was slipping enough to build that amount of heat, I would have noticed it in the way the car drove. I didn't notice any other damage.

I also thought of the bent shaft. It seems hard to believe that I could have bent a steel shaft, but it's easy enough to check.

- Keith

[kfeldt]

My work buddy just suggested that maybe that input shaft bearing failed, and that caused the case to melt. That actually makes a little more sense to me, since it would help explain why I didn't notice a huge change in the car (ie- the slipper slipping excessively). I didn't take a close look at that bearing when I took it out, but I do remember that it didn't look so great.

- Keith

[slow_jun]

Dont know if this would help,when installed my hydra,i noticed the the back plate was hitting the input hile thus binding was present, i reamed the hole and no more binding was felt,maybe,just maybe,the backplate of your slipper is hitting the input hole...

[aconsola]

there are a couple potential issues that I can see you guys having to cause these issues.

first is that there were 2 trans case variations, one later had a bigger hole for clearance for the slipper back plate
see here midway down page:
http://www.rc10talk.com/viewtopic.php?f=27&t=3171&start=15

the other is that there are 2 variations of the slipper back plate.
one has a long shank, and one short with a spacer to go on the top plate.

Depending on what combination of parts you are using you can have different problems with spacing and rubbing

[kfeldt]

Interesting about the two types of backing plates / hubs. Mine is the one-piece version. Maybe that answers my question about how guys are using the B4 slipper. If I try a B4 slipper hub, the surface of the hub rubs against my motor plate. I keep thinking, "if only I had a little spacer..."


Anyway, to make my update... I've been through the trans pretty thoroughly now. I'm pretty sure that the hole is fine. I think I must have had to open it up when I was a kid to fit the slipper hub, and maybe I didn't do such a neat job... which is entirely possible. I cleaned the hole up a little tonight. It looks better, but works about the same.

The input shaft seems straight... it's at least as straight as my kitchen counter is flat. I did clean it up really well tonight, there was a little corrosion in some spots. That might have helped.

After putting everything back together, it seems like it's a bit better. It now has roughly the same amount of runout as my non-slipper transmission from my parts car. I didn't actually test it with a motor tonight. I probably wouldn't be able to sleep if it didn't work...

Like I mentioned above, I've also been trying to get a B4 slipper to work on this car. Aside from the rubbing issue, the B4 hub has even worse runout. It's almost like the hub itself is bent, or it's not sitting squarely on the shaft.

Now that I look at the picture of the newer, two-piece, Losi slipper hub, I wonder if that spacer would help square the hub up...

- Keith

[highwayracer]

Unfortunately, that's a common characteristic of the LRM transmission. Back in the day, I use to always check that and replaced gearbox halves as soon as I felt any play. The bearings were good and I used an A&L slipper with an A-main top shaft...so it had nothing to do with the losi slipper.

If there's only a little play, you can put a thin layer CA in the bearing support to take away the play.

[kfeldt]

One thing I forgot to mention. My instructions for the friction slipper say to replace the E-clip supporting the spur gear side bearing of the input shaft with a smaller C-clip. I hadn't done this originally. I changed it, and it did seem to help.

I ran the car for a while yesterday afternoon. Everything seemed to work fine; no objectionable sounds from the car.

I pulled the motor off after my run and checked the spur gear runout again. It was nearly perfect! I wonder if the friction material needs to wear in a little and that improves the alignment?

[minreg]

So did that bearing check out okay?

[kfeldt]

Yes, the bearing seemed fine.

- Keith