TAMIYA F103 RM

Old 02-01-2009, 08:09 PM
  #1351  
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Originally Posted by liljohn1064
Is the R rear axle solid? The 3 racing ones are NOT. At $8.00 I thought it would be a steal. It didn't last one practice.
it looks solid, as in the ends of the axle are closed..
what is inside is anyone's guess.. I hope to never find out during racing thats for sure!!

i have raced my F103R 2 race meets now and when i was swapping tyres i decided to unscrew the rear left side (easier, less hassle as no diff) and saw only the faintest of outline in the axle of the grub screw..
it was no worse than what my TC lower deck looks like where the downstops contact the chassis, in actual fact it was a hell of a lot better!

maybe someone has broken one and can tell us?
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Old 02-02-2009, 12:03 AM
  #1352  
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Just a note on the 3 Racing CF axle.

I had one and it lasted only 3 races, before it drilled holes where the grub screws contacted. It was rubbish.

In between ordering it and using I had read about them being hollow.
However, I broke it into 3 pieces before sending it to the bin.
It was solid. That surprised me.

I don't think 3 racing have the best quality control.
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Old 02-02-2009, 09:15 AM
  #1353  
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Originally Posted by kavadni
Just a note on the 3 Racing CF axle.

I had one and it lasted only 3 races, before it drilled holes where the grub screws contacted. It was rubbish.

In between ordering it and using I had read about them being hollow.
However, I broke it into 3 pieces before sending it to the bin.
It was solid. That surprised me.

I don't think 3 racing have the best quality control.
I've ordered a couple more and if they show up hollow, I'm going to gorilla glue a rod down the center. I'm going to cut a small piece of steel to insert into the grub screw dimples so it doesn't damage the shaft also. I'll send results after testing this theory also.

J
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Old 02-02-2009, 09:59 AM
  #1354  
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Originally Posted by jrxs-r
If your thrust bearing is old, replace it. If it is a new unit, flip the thrust bearing over and try again. It only goes in one way. Failing that, check to see if the breville washers (curved washers) are fitted in the correct positions.
It looks like the thrust assembly can go either way to me. It is not different on one side than the other. I did try to flip it though based on your recommendation. It is still really tight. If I tighten everything down without the rim and remove the excess gap, the diff is smooth as glass. The minute I put the rim on,, it turns to junk. I tried a new gear, balls and bearings. This is a NEW out of the box kit.
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Old 02-02-2009, 10:16 AM
  #1355  
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While some thrust bearings are side specific, Tamiya's isn't one of them. The ones that are side specific are usually the ones that are in 3 pieces instead of the one piece units Tamiya uses. Usually on things like the clutch bell on nitro cars.
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Old 02-02-2009, 10:16 AM
  #1356  
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Originally Posted by 240Z
As noted, the grub screw does not seat well with the carbon shaft. I was thinking of machining a piece to fit in the slot for the grub screw to seat against to fix the problem. I have heard rumors of the carbon cracking.

Aluminum bends. Not a major bend, but just enough to tweak it and make the wheel wobble. Be prepared and buy several if you plan to run it.
You're right about the grub screw wearing into the graphite/carbon rear axel. But there is a fix for it. All you need to do is purchase a piece of brass shim stock from your local hobby shop. Use some metal cutter to cut the shim stock down to fit the flat surface of the axel. Next apply a little CA to secure it into the place. Test fit it into the hub to make sure it doesn't rub. If it does rub or bind, use a small file to knock down the edges, small bits at a time and test fit again. Once it's fitted properly you all set. The grub screw will seat into the brass and wont split the graphite. I've done this for years and works really well. Occasionally you might have to replace the brass shim but the axel will be great shape and last longer.

Regarding your statement about the aluminum rear axel, you're SPOT ON. The aluminum tweaks just a little but makes a huge vibration in the car. The graphite will bend but usually recover from a hit, or snap all together. I'd stay away from aluminum or titanium rear shafts. Just my opinion.
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Old 02-02-2009, 10:43 AM
  #1357  
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Originally Posted by Jamie Hanson
It looks like the thrust assembly can go either way to me. It is not different on one side than the other. I did try to flip it though based on your recommendation. It is still really tight. If I tighten everything down without the rim and remove the excess gap, the diff is smooth as glass. The minute I put the rim on,, it turns to junk. I tried a new gear, balls and bearings. This is a NEW out of the box kit.
I know this question may seem just a little insulting...but...is the wheel seated all the down on the hub properly. The Tamiya wheels have a tendency to hang up when mounting. It's usually the thrust assembly in the wheel itself that catches during mounting. You can tell by looking at the inside of the wheel where it seats to the hub. If there's a small gap, say half a mm your not on properly. I've seen guys do this at the track and their diffs feel inconsistent, sort of hard, soft, hard, soft. I hope this helps
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Old 02-02-2009, 11:29 AM
  #1358  
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Originally Posted by Jamie Hanson
It looks like the thrust assembly can go either way to me. It is not different on one side than the other. I did try to flip it though based on your recommendation. It is still really tight. If I tighten everything down without the rim and remove the excess gap, the diff is smooth as glass. The minute I put the rim on,, it turns to junk. I tried a new gear, balls and bearings. This is a NEW out of the box kit.
I don't know if this was asked yet, but...

Did you grease the thrust bearing? I know the manual doesn't ask you to, but you should anyway. Every other car I've ever built calls for the thrust bearing to be greased with thick grease. When I first built my 15th Anniversary edition, I didn't grease it, thinking Tamiya must have some reason for not calling for grease on it in the manual. Then when I put the wheel on and adjusted the diff, the diff was notchy and not smooth at all. Went back and greased the thrust bearing with Tamiya's AW grease(really pack it on there!) and re-assembled everything, and the diff was as smooth as glass.

If you haven't already, you might try this.
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Old 02-02-2009, 11:34 AM
  #1359  
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Bingo....i'd bet money that's the issue. Tamiya thrust bearings need to be slathered with AW grease.
Originally Posted by Darkseid
I don't know if this was asked yet, but...

Did you grease the thrust bearing? I know the manual doesn't ask you to, but you should anyway. Every other car I've ever built calls for the thrust bearing to be greased with thick grease. When I first built my 15th Anniversary edition, I didn't grease it, thinking Tamiya must have some reason for not calling for grease on it in the manual. Then when I put the wheel on and adjusted the diff, the diff was notchy and not smooth at all. Went back and greased the thrust bearing with Tamiya's AW grease(really pack it on there!) and re-assembled everything, and the diff was as smooth as glass.

If you haven't already, you might try this.
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Old 02-02-2009, 12:16 PM
  #1360  
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Originally Posted by Vyger
You're right about the grub screw wearing into the graphite/carbon rear axel. But there is a fix for it. All you need to do is purchase a piece of brass shim stock from your local hobby shop. Use some metal cutter to cut the shim stock down to fit the flat surface of the axel. Next apply a little CA to secure it into the place. Test fit it into the hub to make sure it doesn't rub. If it does rub or bind, use a small file to knock down the edges, small bits at a time and test fit again. Once it's fitted properly you all set. The grub screw will seat into the brass and wont split the graphite. I've done this for years and works really well. Occasionally you might have to replace the brass shim but the axel will be great shape and last longer.

Regarding your statement about the aluminum rear axel, you're SPOT ON. The aluminum tweaks just a little but makes a huge vibration in the car. The graphite will bend but usually recover from a hit, or snap all together. I'd stay away from aluminum or titanium rear shafts. Just my opinion.
Thanks for confirming the axle issue Vyger. I will be purchasing some brass stock from the shop. I think its even the right width and just need to trim som off with a sharp snips or linesman's scissors.
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Old 02-02-2009, 12:31 PM
  #1361  
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Originally Posted by Core Creations
Bingo....i'd bet money that's the issue. Tamiya thrust bearings need to be slathered with AW grease.
I have not used the grease but I HAVE used some silicone diff lube already with no luck... I will try the grease instead... I do not have high hopes though based on the fact I assembled the diff without the rim on the car. I used some old thrust washers to take up the play that the rim normally would, and the diff was great that way. It is only when the thrust assembly is installed inside the rim....
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Old 02-02-2009, 12:42 PM
  #1362  
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I think I figured it out. Thank you to all that offered some suggestions....
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Old 02-02-2009, 01:22 PM
  #1363  
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It seems to be no secret that some times racers have a little go fast secret that they keep to themselves. This weekend I decided to try out one that I picked up from a hint here at RC Tech and found it to be a godsend for my F103.

To get to the point it is the 3.5mm Offset Upright option part from Tamiya part #53259. I spend an hour trying to chase down an appropriate radio setting to help settle down my car with minimal success. I ended up in a wreck that sent me into the pits to change out the control arms and decided to put in the option part upright while I had everything apart. When I put my car back on the track it was like night and day. Steering was still very responsive, but it was now more predictable.

Please someone correct me on this, but I believe it adds some effective castor resulting in better front end tracking. Anyway, what ever it is it is good stuff for my driving “style”. At the risk of loosing a position or two to the competition, it is too good to keep to myself.
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Old 02-02-2009, 01:51 PM
  #1364  
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That is an interesting tip on the offset steering blocks, most all 12th and 10 pan cars use an offset steering block rather than a centered one like the stock Tamiya, plus the F103 does not have much static caster,and the lack of camber, all lead to a nevrous and twitchy car in most cases , gonna have to give those a try.... I believe non offset steering blocks might be more popular in oval...
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Old 02-02-2009, 02:30 PM
  #1365  
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The offset steering block is an old trick used back when many were still trying to get the "hop-up" pivot ball rear end to work. In the end the fastest consistent result was to go back to the o-ring setup with the stock front end. The erratic feeling many find with the car is a result of the lack or rear dampening when using the pivot ball rear end w/o tweak screws.
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