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Tamiya mini cooper

Old 06-22-2013, 01:33 AM
  #19081  
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Originally Posted by c-lyon
The S comes as a 210, but with bits to change to other wbs. You just can't use the stock S rear aluminum chassis piece, but have to change to plastic for mwb and lwb.
Some minor aluminum steering bits.
If you flip the rear arms over and find longer fixings to remount the shocks (I use my unused rear anti roll bar mounts) you can fit the alloy plate to make the chassis into a medium wheel base.
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Old 06-22-2013, 06:43 AM
  #19082  
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M05 Ball Diff keeps coming loose. It ran fine for 2 races, now after a short period of running the screw used to tighten the diff works loose. Anyone else have this problem or a solution? I have the diff mounted so you access the screw from the Right-hand side of the car. Should I flip it around? It seems to come undone under braking.
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Old 06-22-2013, 03:55 PM
  #19083  
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OK thanks for the info, shawnh. I was just going by the manual instructions. (What do they know.)
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Old 06-22-2013, 06:40 PM
  #19084  
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Originally Posted by ic-racer
M05 Ball Diff keeps coming loose. It ran fine for 2 races, now after a short period of running the screw used to tighten the diff works loose. Anyone else have this problem or a solution? I have the diff mounted so you access the screw from the Right-hand side of the car. Should I flip it around? It seems to come undone under braking.
I tore it apart and can answer my own question here. This may help someone else out also.

The reason the screw loosens is that the thrust bearing freezes up. The cure was to flush the thrust bearing very well and re-lubricate it with thrust bearing grease. I used some green thrust bearing grease I had left over from my 1/8 On-road days. Of note, in the instructions it indicates to use thrust bearing grease but it is not included in the diff kit.

If the thrust bearing is lubricated with the wrong substance it does not spin freely and the diff action is not smooth. I initially thought it was the diff balls and plates causing the stiffness, but it wasn't; it was the thrust bearing not spinning freely when the screw is tightened tight enough to keep the diff from slipping.

I'm also going to make sure I put that little pink foam piece in the cup. That will help keep debris out of the bearing. One little piece of grit in that bearing and it will freeze up and cause the screw to loosen.
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Old 06-23-2013, 08:34 PM
  #19085  
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Originally Posted by ic-racer
I tore it apart and can answer my own question here. This may help someone else out also.

The reason the screw loosens is that the thrust bearing freezes up. The cure was to flush the thrust bearing very well and re-lubricate it with thrust bearing grease. I used some green thrust bearing grease I had left over from my 1/8 On-road days. Of note, in the instructions it indicates to use thrust bearing grease but it is not included in the diff kit.

If the thrust bearing is lubricated with the wrong substance it does not spin freely and the diff action is not smooth. I initially thought it was the diff balls and plates causing the stiffness, but it wasn't; it was the thrust bearing not spinning freely when the screw is tightened tight enough to keep the diff from slipping.

I'm also going to make sure I put that little pink foam piece in the cup. That will help keep debris out of the bearing. One little piece of grit in that bearing and it will freeze up and cause the screw to loosen.
This just doesn't sound right. My time with the 05 ball diff is very limited, but didn't the diff screw go in from the left hand side of the car, if viewed from the rear??? Most of the problems with this diff came from improper assembly and over tightening the diff screw. This diff does not respond well to efforts to stiffen the diff action like that of the TA03 ball diff.
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Old 06-24-2013, 04:47 AM
  #19086  
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Hi,

I think the orientation of the thrust bearing is important. The center part is bronze in color, one side is flat, the other I think beveled.

The beveled faces the long screw head.

Hope it helps.
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Old 06-24-2013, 05:47 AM
  #19087  
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I also put a small drop of blue (non perminant) loctite on it to hold it in
my driver hasn't had any complaints about it yet and we haven't noticed any maintenance issues yet either
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Old 06-24-2013, 09:19 AM
  #19088  
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Originally Posted by Granpa
This just doesn't sound right. My time with the 05 ball diff is very limited, but didn't the diff screw go in from the left hand side of the car, if viewed from the rear??? Most of the problems with this diff came from improper assembly and over tightening the diff screw. This diff does not respond well to efforts to stiffen the diff action like that of the TA03 ball diff.
+1

I tried to overtighten it to stiffen up the M05 ball diff. It broke after a few races. Went back to TA 03 ball diff
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Old 06-25-2013, 10:40 AM
  #19089  
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FX35rc, +1, had the same experience. Tried to tighten the M05 diff to make it as tight as the TA03 diff in my M03, and the screw broke after a few batteries. But I didn't go to the TA03 diff, I wanted to keep it all M05, and just learned how to build the M05 diff better. Yes, you need ceramic balls, buff the rings, good thrust bearing and all that (can you tell I hang out with Grandpa?), just don't tighten the poop out of it. Tight, then back off a little, find that smooth spot, still resistant but smooth. On our rather open outdoor asphalt track, this is the way to keep your speed up and get great steering. Now it's just up to you to hold it on line!
If all the stars line up, I think I can lap my M03 a tiny bit faster than the M05. If conditions aren't perfect, the M05 is easier to drive and more consistent. It's got something to do with weight balance...
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Old 06-25-2013, 11:52 AM
  #19090  
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Originally Posted by Laguna Bozo
FX35rc, +1, had the same experience. Tried to tighten the M05 diff to make it as tight as the TA03 diff in my M03, and the screw broke after a few batteries. But I didn't go to the TA03 diff, I wanted to keep it all M05, and just learned how to build the M05 diff better. Yes, you need ceramic balls, buff the rings, good thrust bearing and all that (can you tell I hang out with Grandpa?), just don't tighten the poop out of it. Tight, then back off a little, find that smooth spot, still resistant but smooth. On our rather open outdoor asphalt track, this is the way to keep your speed up and get great steering. Now it's just up to you to hold it on line!
If all the stars line up, I think I can lap my M03 a tiny bit faster than the M05. If conditions aren't perfect, the M05 is easier to drive and more consistent. It's got something to do with weight balance...
Thank you Sir!. I will do your M05 ball diff route then. I need to work on how to hold the line..hahaha. I still get nervous and drive off line when another mini comes up behind me.

Danny
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Old 06-25-2013, 03:31 PM
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Originally Posted by Granpa
but didn't the diff screw go in from the left hand side of the car, if viewed from the rear???
The M05 diff assembly is symmetric. One could put it in the car either way.
Most of the problems with this diff came from improper assembly and over tightening the diff screw. This diff does not respond well to efforts to stiffen the diff action like that of the TA03 ball diff.
I don't have any experience with stiff diff action or improper assembly problems but wanted to emphasize the importance of the thrust bearing in proper diff function.

If you compare the M05 diff thrust bearing to the TRF417 diff bearing the M05 thrust bearing seems smaller, more fragile and is non-rebuildable and not protected from the elements by the adjustment screw. Likely more prone to failure if a small amount of grit gets in there. I got the impression the balls were smaller but did not measure this to know for sure. When I compared the action of the two in my hands, the reason my TRF417 diff was smoother was the thrust bearing, not the diff balls. After cleaining and re-lubing the trust bearing in my 'ready for the junk bin' M05 diff, the two diffs had nearly identical smooth action.
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Old 06-25-2013, 04:23 PM
  #19092  
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Just came in to check the Mini thread after rebuilding the TA03 ball diff in my M03 LWB. A huge contact with a board required the replacement of a front chassis half, so it seemed like a good idea to redo the diff since it was built over a year ago.

I posted how to build a TA03 diff awhile back so won't bore anyone with it. Just want to say that the diff was still smooth, but I wanted to tighten it a bit. What I found in the teardown was that the diff rings showed almost no wear and just needed a touch up with some 600 paper and a quick buff with some polish. What I did find was that one of the large Belleville washers had "flattened" and needed replacement. That was why the diff seemed looser than my others.

As Craig said, attention to detail will pay off----also good driving. The M05 diff is "tricky" to build correctly and little stuff can really trip you up. As I recall you had to flip the diff over halfway thru the build to get everything in the right places. Lapping and polishing the diff rings should help keep the diff smooth much longer than stock. Ceramic diff balls are a good investment cause you don't have to replace them every time you rebuild the diff. It's actually cheaper.
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Old 06-25-2013, 05:47 PM
  #19093  
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I love my ceramic balls.

Seriously though, even the cheapest ceramic balls out there are miles ahead of the stock steel ones. I believe mine cost about $5 a few years ago. The diff has always been smooth since I got them and has required less maintenance. The only downside has been that I've never been able to get it locked up as much as I used to. I think the steel balls actually got crushed when I used them.
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Old 06-25-2013, 05:53 PM
  #19094  
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Originally Posted by ic-racer
The M05 diff assembly is symmetric. One could put it in the car either way.


I don't have any experience with stiff diff action or improper assembly problems but wanted to emphasize the importance of the thrust bearing in proper diff function.

If you compare the M05 diff thrust bearing to the TRF417 diff bearing the M05 thrust bearing seems smaller, more fragile and is non-rebuildable and not protected from the elements by the adjustment screw. Likely more prone to failure if a small amount of grit gets in there. I got the impression the balls were smaller but did not measure this to know for sure. When I compared the action of the two in my hands, the reason my TRF417 diff was smoother was the thrust bearing, not the diff balls. After cleaining and re-lubing the trust bearing in my 'ready for the junk bin' M05 diff, the two diffs had nearly identical smooth action.
Yeah, you're absolutely right that proper functioning of the thrust bearing is important. Not disputing the point. I just don't think much "grit" can get to the thrust bearing cause the diff is more or less sealed from the elements by the chassis halves.

Yes, the diff can be installed in the car either way. Since I'd only used a M05 diff for about a year and that was several years ago, I vaguely remembered that the diff adjustment screw belonged on the left. That's why that was posed more as a question rather than a statement.

There is one point I do have to disagree with you on though. We all have improper assembly problems. I've had my share and didn't your problem start by your not lubing the thrust bearing?????? You can't have a stiff M05 diff cause you'll break the screw if you try.

Can't comment on a 417 part cause frankly, I don't have one nor could my racing budget support one.
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Old 06-25-2013, 06:38 PM
  #19095  
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Ok am looking to the experts for some input. My M05 has an issue with serious oversteer. I can't go into a corner aggressive at all or with any real amounts of speed without the rear coming around on me.

Now with my TC experience this sounds like a rear droop issue. When my TC's do it I take the droop screws in till I am happy. Unfortunately the mini as we all know does not have these. So would spacers in the shock serve the same purpose? If so how many would be a good starting point?

My shocks are the TRF mini shocks built per the instructions. But when the caps were put on I had the pistons at the bottom of the shocks (fully extended). Could the rebound be causing an issue as well?

Thanks in advance,
Jason

P.S. At this point I have a whopping 2oz of lead over the rear axle in order to try and tame it. I would like to ditch this if at all possible.
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