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Old 12-10-2001, 05:02 PM   #541
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Overgear, I'm thinking of posting an article on my homepage about how I build my diffs. But I guess that might take some time so I will explain here.

1. If you rebuild your diff, first clean all parts.

2. Take a 1200 sandpaper and sand one face of each diff rings. The sanded side should face towards the diff balls and not as Course-R recommends(no pun intended), towards the hubs. I can't understand how that helps since the rings can't slip against the hubs anyway due to the d shaped rings.

3. Complete the assembly according to the instructions.

4. When you have bottomed out the spring, there are two ways to get the right setting. Either do per instructions, and check the setting after 1-3 runs OR back off only 1/4 turn. This way the diff will be a bit tight to begin with, but it will get right after a few runs.

The good thing about sanding the rings are that you can run the diff looser without slippage and that you can reuse old rings over and over again. Just sand them until you have got rid of the groove from the balls.

With this technique I have managed 150+ runs without a need to rebuid the diffs.

Anyone else using this sandpaper technique?

Last edited by Airwide; 12-10-2001 at 05:04 PM.
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Old 12-10-2001, 05:15 PM   #542
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Quote:
Originally posted by Airwide


4. When you have bottomed out the spring, there are two ways to get the right setting. Either do per instructions, and check the setting after 1-3 runs OR back off only 1/4 turn. This way the diff will be a bit tight to begin with, but it will get right after a few runs.
back off only 1/4 turn after the spring bottom out? isn't that TOO tight?
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Old 12-10-2001, 05:22 PM   #543
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it's tight, but if you don't want to readjust the diff after a few runs you have to start tight to prevent slippage later on.

Personally I use the method in the instructions.
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Old 12-10-2001, 06:45 PM   #544
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Also, remember, the plastic diff and the metal diff are assembled DIFFERENTLY!!!! If you are assembling the plastic diff like you would a metal, that's the problem.

Corse-R: I understood what type of suspension you meant, I just liked the word 'blobby'. It's so....ummm, descriptive!!!!
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Old 12-10-2001, 09:23 PM   #545
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Quote:
Originally posted by Corse-R


If you race in a bumpy track and/or doesn't have the grip you desire, you need to:

1- go lighter in oil and springs. My experience says me that stock springs work very good, maybe a blue spring at rear with 40 or 50 with the bigger pistons front and medium rears.

2- Raise your car. The sum of a lighter car in suspension and higher in clearance, gives us a higher roll center and thus, when cornering, help us to get more grip. The cars is more blobby but docile to drive on these conditions

3- Fitting inwards the upper shock position (center at front, center or inner at the rear should help too).

What you said: Bad idea my bro. If you soften only the front, when you throttle off, the weight distribution sends the weight of the car to the front, increasing steering and reducing grip at the rear, when you accelerate, it occurs the opposite, the weight in front is reduced and you loose steering when you're getting out the turns and hairpins.
The two things I did not try was raising the car and using the stock springs. I am familiar with the XRAY entering and exiting the turns with much more speed. I may have been trying to force the TC3 to do the same.

Bullseye had my car for a few laps and said the car was great but had too much steering for him. So I may need to work more on the driver and less on the car.
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Last edited by RCCadet; 12-10-2001 at 09:28 PM.
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Old 12-10-2001, 11:07 PM   #546
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Quote:
Originally posted by over gear


back off only 1/4 turn after the spring bottom out? isn't that TOO tight?
I race modified and my local track has very high grip and my diffs goes more tighter, after diff seating, I loose a little more, possibly more than a 1/8 of a turn, but less than a 1/4 of a turn (front diff), the rear goes with a 1/4 of a turn directly (looser).
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Old 12-10-2001, 11:46 PM   #547
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It's time I rebuilt my diffs but I have a few questions.

I have the old steel diffs, so which parts would I need to convert to the composite outdrives?

Also, do you change all the ball bearings (diff/thrust) when you clean the diffs. So far I have just been cleaning, flipping the diff ring and regreasing. This has worked well and the diffs feel really smooth.

I tighten my diff all the way until the white bit fits snug in the diff half. After that I back off the screw about 1/4 of a turn as described in a previous post. My diffs definetly loosen after a few battery packs.

Thanks

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Old 12-11-2001, 12:54 AM   #548
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Quote:
Originally posted by Yorkie
I have the old steel diffs, so which parts would I need to convert to the composite outdrives?

Also, do you change all the ball bearings (diff/thrust) when you clean the diffs. So far I have just been cleaning, flipping the diff ring and regreasing. This has worked well and the diffs feel really smooth.

I tighten my diff all the way until the white bit fits snug in the diff half. After that I back off the screw about 1/4 of a turn as described in a previous post. My diffs definetly loosen after a few battery packs.
The plastic diffs are little different to the steel ones. Is best to buy the complete diff and install new from scratch rather than upgrading the steel ones (the outdrives, the diff rings, the inner BB are different). The only you can use from the old ones to the plastic are the balls, the thrust bearing and the screw that holds all in one piece.

Loosening of the ball diffs is normal, after seated, you should check often to tighten a little, if is needed.
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Old 12-11-2001, 08:11 PM   #549
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I've got a tc3 and I love it. Theres only one strange thing I've found on it. When i have th diffs case tops off and I put a diff in one of them, I can spin the diff and it keeps spinning for a long time. But if I put it in the other diff case, it only spins for a few rotations. Any ideas on that one? I tried playing around with the shims and stuff, but it didnt seem to help. I know it CANT be good that it spins freely in one and not in the other.........but my car is still mega fast ........no complaints though
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Old 12-11-2001, 08:15 PM   #550
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When I rebuild my diffs I back it off 1/2 a turn...works good for me, car handles like a dream. I race on no bite asphalt thats really bumpy.
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Old 12-11-2001, 08:55 PM   #551
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Are you using the composite diff pieces or the steel ones? If I remember correctly you have to trim some of the transmission cases by the bearing area if you are using the composite pieces. Try putting the diff in the other piece of the gear cover and see if it spins just as free. If it does then maybe the two pieces don't match up evenly. I am sure more people will have some ideas.
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Old 12-12-2001, 09:09 AM   #552
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thanks kraig

Im using the composite cases. I'm gonna try what you said and see how it works. Neither of them spin freely when the cases are put together, they only spin a few revolutions, not like it does when the case is apart and it spins forever
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Old 12-12-2001, 04:13 PM   #553
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i agree with corse-r. i found out about the difference between the 2 diff outdrives (steel and composite) the hard way - i bought the composite outdrives only, but while assembling, i ended up buying several more stuff (diff rings, diff nut, etc.) it is better to buy the whole diff assembly. i also couldnt figure out why the composite outdrives bind in the gearbox until someone told me about the different sized bushings (the steel outdrives use bearings.) now, everything spins smoothly. i did trim a bit off the gearbox where the outdrive bearings sit on.
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Old 12-12-2001, 06:45 PM   #554
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why would one run the car with a tigher front diff ? wouldn't that cause push ?
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Old 12-13-2001, 01:04 AM   #555
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Quote:
Originally posted by marvi
i also couldnt figure out why the composite outdrives bind in the gearbox until someone told me about the different sized bushings (the steel outdrives use bearings.) now, everything spins smoothly. i did trim a bit off the gearbox where the outdrive bearings sit on.
I haven't experienced any binding on the gearbox, I only removed the outdrive shims and all sprins completely freely.

TIP: If you are assembling a new tc3, you should so some 'break-in' to the transom. To do this, install an old motor or a worn stock, with a higher ratio (about 7 or 8:1) and connect to an old 4 cell battery pack and let run for several minutes, doing this you achive an can detect any binding on the transmission, before any weird thing occurs (fried motors, esc damaged and other ugly things).
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