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Old 01-30-2008, 12:41 AM   #1
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Exclamation Torque steer and slipping rear diff issues...

Im having issues with my diff rear diff slipping now. The 13.5 is pumping massive amounts of torque into it and unless its pretty tight, its gonna slip and melt (already happened). From what i know, a tight rear diff means it will slide out more in turns. Bleh. Torque steer is also now an issue. Brushed stocks didnt put out enough torque to make it an issue. I took off my chassis stiffner bars but i guess the torque from the motor is flexing it so i gotta put my stiffners back on now and see if that helps. The issue with the rear diff is reaaaaly botherin me though. I may have even tweaked the steering or something because during my q, after a hit it was tracking funny and i couldnt go down the straight easily and the turns were even harder. I was fighting it to go straight. After the race, i drove it around and it seemed to be going straight, then id gas it and it'd torque steer but other than that it was alright. I dont know whats goin on.

This is my car: a Tc3



those pics are pretty old though. Ive got a 13.5/GTB setup now and aluminim drive shaft. Like i said, im gonna try putting the stiffner bars (bars running along the outside of the car) back on and see if that helps any. The rear diff issue is really bothering me as i said and one person i know said the wheel bearings might be too tight...

anyone else got any ideas? Any TC3 veterans here have a guide to dealing with torque steer? Any brushless vets able to tell me if the torque is making the diff slip or if its something else? Analyze my post! Lemme know what i can do, please!

Thanks
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Old 01-30-2008, 12:55 AM   #2
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I'm guessing you are using the stock plastic diffs then?? try using a steel diff or an aluminium one from IRS.
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Old 01-30-2008, 01:12 AM   #3
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ill consider that. Anything that can be done without a steel/aluminum diff upgrade though?

edit: didnt find those option parts on the IRS website...
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Old 01-30-2008, 01:21 AM   #4
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They might be under TC4, or they possibly aren't making them any more, steel diffs from either the NTC3 or TC4 will fit fine.

A 13.5 shouldn't be making you torque steer, it is either the diff slipping or you have a tweak in the chassis.

There isn't really much you can do to stop the plastic diffs melting apart from making sure they don't slip.
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Old 01-30-2008, 01:25 AM   #5
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Originally Posted by fathead View Post
They might be under TC4, or they possibly aren't making them any more, steel diffs from either the NTC3 or TC4 will fit fine.

A 13.5 shouldn't be making you torque steer, it is either the diff slipping or you have a tweak in the chassis.

There isn't really much you can do to stop the plastic diffs melting apart from making sure they don't slip.
so basically...something else is causing my torque steer and that same "something else" may also be causing my diffs to slip? Im sure plenty of people run 13.5's with regular plastic ball diffs and dont have this isssue...

how would the diff slipping cause my torque steer?
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Old 01-30-2008, 02:20 AM   #6
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Originally Posted by Syber Serulean View Post
so basically...something else is causing my torque steer and that same "something else" may also be causing my diffs to slip? Im sure plenty of people run 13.5's with regular plastic ball diffs and dont have this isssue...

how would the diff slipping cause my torque steer?
I would guess he's actually saying it's two seperate issues.... Your diffs slipping is because of the plastic diffs.

The torque steer is because of chassis tweak.. not slipping diffs. You mention the car tracks odd when accelerating hard, but seems to go straight on a steady throttle... classic signs of tweak.
You also mention you've removed the sitffeners from the chassis. I assume you mean the side braces? if so, without a top deck, that'll may the car very susceptable to tweak, as it's only the bottom plate that is absorbing any impact, meaning it is quite likely to have tweaked.

Best thing to do is take the plate off, and check that is flat first. then re-build the car on a flat surface, and make sure there is no rocking happening when it is all back together. Finally, borrow a tweak board, or have some at the track show you how to set up your car with no tweak (need to adjust the spring collars).

If you've just thrown the brushless in, bear in mind that the speedo is pretty heavy compared to a brushed one, so the weight balance is probably slightly different.

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Old 01-30-2008, 02:40 AM   #7
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so plastic diffs cant handle a 13.5 or what?

but yeah, ill first put the side braces back on and get it all set up on a tweak board. Ill see how that goes. If that still doesnt work, what exactly do i rebuild? I recently changed out the diff cases for new ones (old ones stripped)...but then again i didnt touch the bulkheads....

...except the rears...hmm i see what to do now. At least in the rear more than the front. Hmm, thanks for the info. You say to take the plate off then check if its flat...what plate? Its hard to see in the pictures but it also has a reinforcement brace running down the center of the chassis under the shaft.

edit: mad props to whoever can link me to the stronger steel diffs. All i can find is http://www.gohobbies.com/itemASC-3913.html and i cant tell if thats the steel version because a FAQ on the AE website says to switch to "part #31128" which ive also seen referred to as "AS31128" but i cant find the 31128 part ANYWHERE online. Are they the same thing? The parts list on the FT Tc4 for "steel diff kit" says part #3918 blahhhhh. Help meeeeee thx


did some searching...this what im looking for?
https://www.ssl-stormerhobbies.com/c...=ns&pn=ASC3918
http://www3.towerhobbies.com/cgi-bin...&I=LXXH05&P=OW

if i get one, do i have to get a 2nd? or can i have the steel diff in the ack and the regular in front?

Last edited by Syber Serulean; 01-30-2008 at 03:31 AM.
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Old 01-30-2008, 07:29 AM   #8
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I had the same problem with my tc3 and a 19t brushed motor before I gave up on it and got something more reliable.

You need to either setup the diff's real perfect or invest in the metal outdrives.

The problem is if you set the diff slightly too loose (and I meen slightly) any diff slip is then generated into heat onto the main diff rings... which in turn will melt your outdrives quite happily

Set the diff too tight and you run the risk of either flatspotting the balls, ruining the diff plates... or both

So, I would say you are more likely to get a better diff setting by rebuilding it with metal outdrives, ideally get both done or the plastic one remaining will be under strain and fail.
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Old 01-30-2008, 07:30 AM   #9
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double post
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Old 01-30-2008, 07:45 AM   #10
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triple post, damn connection...
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Old 01-30-2008, 09:14 AM   #11
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Quote:
Originally Posted by Syber Serulean View Post
but yeah, ill first put the side braces back on and get it all set up on a tweak board. Ill see how that goes. If that still doesnt work, what exactly do i rebuild? I recently changed out the diff cases for new ones (old ones stripped)...but then again i didnt touch the bulkheads....

...except the rears...hmm i see what to do now. At least in the rear more than the front. Hmm, thanks for the info. You say to take the plate off then check if its flat...what plate? Its hard to see in the pictures but it also has a reinforcement brace running down the center of the chassis under the shaft.
I meant the main chassis plate itself. It's a big job, yes, but it would be my first port of call.

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Old 01-30-2008, 01:18 PM   #12
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Quote:
Originally Posted by TryHard View Post
I meant the main chassis plate itself. It's a big job, yes, but it would be my first port of call.

HiH
Ed
ok thanks, tryhard.



so then all i need to buy are the metal outdrives? I dont need to buy an entire new diff kit? Just metal outdrives and new thrust washers? (i think the stock ones are D shapes and the better ones are complete circle).
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Old 01-30-2008, 03:53 PM   #13
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Default TC3 diff & IRS

The outdrives are on the IRS site part number IRS2140. Note that you MUST fit their pincushions to your driveshafts else the outdrives last about 10min (steel pin in aluminium diff half).

We ran TC3s for years like this absolutely NO diff problems in either 27, 19 or 12turn.
Make sure to check the pincushions regularly as if you run with the plastic outer worn through its the same as the steel pin.

I'd suggest you fix the diff first then see how bad your torque steer is. The TC3 always had torque steer to some extent but it was never unmanageable.
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Old 01-30-2008, 04:15 PM   #14
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Default TC4 steel outdrives

The part number is ASC31062 on the Stormer website that you found ASC3918 on.

Note that if you go for the steel outdrives you also need different diff rings (you can see them in the ASC3918 picture ) they are totally round rather than the inner edge having a D shape. The good news is that as the diff halves are lightened steel you don't have to change the pins in the driveshafts.
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Old 01-30-2008, 05:21 PM   #15
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sounds like its best to go with the lightened steel outdrives and new diff rings then since it seems to be a direct drop in replacement and i dont have to change any pins then right?

what else would i need to make those outdrives fit for my Tc3? I thought there are tiny fitment differences with the diffs between the Tc4 and Tc3 (something about bearings or bushings i think)...


edit: not that its viable...but if i can find someone to make a lightened drive shaft out of titanium, that would mean less rotating mass and could also result in less torque steer...what do you guys think? Just wanna give my tc3 a leg up before i finally move on by the end of the year (or next year even).

Last edited by Syber Serulean; 01-30-2008 at 05:47 PM.
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