My first Nutech - Rebuilding a broken TB2

[Mexxan]

Hi all - Well,... said I'd never do it again. After buying a used 5T on Ebay and finding out that it was practically DOA when it's description read light use and great condition - I rebuilt the T, but promised myself no more used RC again.

But, I found a bargain on a used ThunderBolt 2 with a description that stated honestly that the previous use and engine condition couldn't be vouched for, I paid a fair price and prepared for the worse.

Now it's here - and their are problems, but I'm looking forward to the wrenching!



http://i389.photobucket.com/albums/oo335/ShoulderShrug/IMG_4330.jpg



http://i389.photobucket.com/albums/oo335/ShoulderShrug/IMG_4347.jpg


First start up around 5 minutes ago - initial and immediate observations:

Major problem - no power to the drivetrain. The 26cc started on the first few pulls so all good there so far (no Outerwears or mesh mod though and the stock filter is full of dirt).

The throttle and brakes work - clutch bell spins with no resistance so it looks like the gears may be toast. Or even more along the drivetrain - yikes.

Can't get the Rx to work both servo's at the same time - it'll work the throttle and steering if plugged in individually, but if both are plugged in it will only work the steering servo with no throttle or brake. Not sure how to crack this one - it's 2.4Ghz, one of the Rx's that came with my Dx3s and it works fine on my 5T.

Body is in pretty good condition with light paint chipping and a few cracks and the tires have very little wear.

Based on my Baja running - and at a guess, this looks like it has only had 3 or 4 tanks - just doesn't look like it's been bashed or used for any length of time.

So good and bad, but overall I'm glad I've finally got a 4WD 1/5th, My 5B and 5T are great but it's refreshing to have something 1/5th and it not be Hpi. Now the hard work starts first largescale 4WD I've worked on it's all pretty new. Thanks in advance - you KNOW the questions are going to start coming - lol.

[mooman007uk]

no drive eh...does it freewheel ok without any bad noises and do both front and rear centre shafts turn when you roll it? one thing I'd check is the pinion cups...they're held in with grub screws and if they come loose the cup will just spin on the shaft...

[mradlin]

Judging by the lack of side guards and the radio box, it looks like you have a tester model. Since you don't know much about the history of your TB2, I'd suggest going over the whole vehicle and double check that all of the bearings move freely and that all of the bolts, nuts and screws are secure. I'd also look into getting some new servos for it, the ones on there have had some issues.
Hope this helps
Mike

[Pipeous]

ya I did some videos to show servo problems on the tester models as I have one myself. check all the grub screws in gears, maybe a wheel hex grub screw or 2 has come loose. your buggy could be mine's brother

[bens_rc]

if it is one of the first batch to come out like mine, there will be a fair chance that either the center or rear diff would have stripped the planetry gears out due to not enough shims in the diff to mesh properly

[Clubin]

Actually, it looks proty good. Check dog bones to make sure they are all intact.

[Mexxan]

Great advice - I'll be actioning them all, so a big thank you. Manage to get everything stripped downand cleaned/lubed. No drive due to the screw and C/E clip missing off the lower pinion/gear so it just wasn't engaging, I'll have to order these unless Hpi ones work. The drive and diffs work fully which is great news although the front one sounds 'unbalanced' with a heavy grinding noise every revolution of the wheels. Did the mesh mod on the engine and cleaned the filter-also added a couple of layers of Redneck too.

Ah, thanks - now I know why the side guards are missing. I paid £225 for it so still a bargain. Opening the diffs up tomorrow I'll definitely check the shimming and wear. Still have to figure put the radio issue - thought it mght be the draw bt if it works fine on a T, should be simple as smooth here too.

Is there anythng else to check / look for while it's apart?

Thanks all for really useful info so far.

[Mexxan]

Looks like I was way off with usage then - if this is a tester it must have been around for a while - is there anywhere I can get a list of the revisions since, so I know what to change / upgrade to match the current stock TB2?

Cheers.

[Pipeous]

we are in the same boat, except mine was new... I ordered 3 aluminum dif cases and front cvd's. end the possible problems right away I figure. you'll have the same knuckle pivot as mine too. the new c hubs look nice.. radio box has been changed.

not much else. rear upper arms ar kind of thin in the rod dept, otherwise I don't see much else to be a problem. watch your droop screws too so the shock pistons don't bottom inside on full extension.

surf around, a few of the guys have done some brilliant mods on theirs. have a look through their threads and copy what you like. yours is apart anyway. spend and hour looking at the mods of each area and do what ya gotta do

I know I can babble with the best, but my bud gunsmith can out babble me any day hehe. not many can

[Mexxan]

Cheers Barry - So Tb2 testers are still around new?

I'm gonna try and keep the cost low although all the Alu gear looks way to good to resist. Got to keep the funds at a decent level for the MM. Unless I manage to selll my 5b - then I'm maxing this baby out!

Got minimal parts damaged / missing - a few clips (reason for no drive - nice and simple), grub screws for the main drive cups and I need to do some major shimming or the diff oil is coming straight out (Is your shimmed up good? I have around a fair amount of movement on my centre diff cups). This is the problem - I can't find the damn small/cheap items I need - the shims, washers and grubs seem to be part of main components. I can find them on CML / Shopatron but that sounds lie a pain to order from (only thing missing are the washers / shims from here). I could get this TB2 up and running for a minimal amount and upgrade as parts go, Really enjoying working on it - a whole lot more accessible than my b/t. The servo's work fine (for now) - just not together! Not sure if it's my Tx/Rx though. Is that the problem you were having? I'm not sure what the droop screws are. Thanks again.

[Pipeous]

I could get one or the other to work without a problem, but as soon as I connected both together they glitched and wigged out. they were drawing more power than a 10 amp bec could supply

[Isle of Wight Basher]

I could get one or the other to work without a problem, but as soon as I connected both together they glitched and wigged out. they were drawing more power than a 10 amp bec could supply

Is that a seperate BEC supply or through the reciever ?, as 2 servos shouldn't draw that amount, so it's either a faulty bec circuit,lead or a short circuit in one of the servos causing too much current draw.

3 largescale servo such as the HS-5745 only draw 2-3 amps under load.

Also is the battery healthy, ie giving 6V plus under load ?

[Mexxan]

Sounds pretty similar but I don't even get to the glitch part. I'll try it with a fully charged newer pack from my B. I'll check out replacement servo's now - the Dx3s is new and working fine with everything I think PodiumRc have most of the small parts but never used them before - still couldn't find the shims / washers. I'll just have to see if I can get a match in a hardware store. Must have a grub in my b/t spares and might see if if a hpi E clip works where the sceibe's should go. Think I'll transfer Baja servos for now just to get this moving - if they fit.

[Mexxan]

oh yeah, thanks Basher cycled my 4500mah pack few times then tried it - and all the servo's are working - great news! I'll keep an eye on them an ditch if they start to go crazy like Barry's.

Need to get my head round the diffs and if the amount of shimming I think is actually needed, Ben's diff comments have got me cacking slightly though, so I need to get this right. I'll post up some pics. Also, I'm not too sure which way to go for diff oils - light bashing on grass, dirt and rarely loose/fine gravel and definitely want to avoid risking a diff blowout. Any recommendations?

[Pipeous]

I tried multiple lipo batteries, different bec's, different radios etc. the servos were bunk. I have been using bec's with lipos in my large scales for a long time as I come from a heli background.

I haven't tested the new version servos in the GT5R yet. so we will se how that goes this week.

from testing mine stock I found the front dif unloads a lot (front wheels balloon on throttle so it is more like front wheel drive, which is because the center dif is unloading the power), so am going to run probably 100k in center, 50k in front and 20-30k in rear and see how that goes. and just shim the gears so they mesh closer together without binding. it's the extra space that no shims have that screws things up. too much play makes the gear ends catch rather than having full contact area. less metal touching wears faster and more chance of binding from a wrong mesh.

[Mexxan]

Finally got my TB2 back and looking clean after a full rebuild. Switched over to diff oils and need to replace a fair few stripped screws but over al it's cost me just £20 so far to get it back running - bargain!



http://i389.photobucket.com/albums/oo335/ShoulderShrug/IMG_4816.jpg


http://i389.photobucket.com/albums/oo335/ShoulderShrug/IMG_4822.jpg


Well, thought I'd start her up just in front of the house to check the steering and brakes Must have been running for 30 seconds and I clip the curb at a crawl and the steering goes. Dodgy servo? No, the servo saver broke - very surprised it was going no more than 8-10 mph.



http://i389.photobucket.com/albums/oo335/ShoulderShrug/IMG_4844.jpg



The wife was watching and she just pissed herself laughing. Still had a great run though - with my 5t! So that means back on the road for £24 :excited: Not bad at all, but shame I didn't get to see how it handles. Might have to go Al instead of the stock brandy snap saver set.

[mynameismud76]

Could it be the saver snapped because it was cranked down a touch tight?

I crank mine down so there's about 7 or 8 mm of thread showing, and have found the steering response to be adequate.

[roccos_van]

Judgeing by the pic your saver is probably too tight. Mine is only around approx 3mm from the top.

[Mexxan]

Thanks for the Saver tips - the TB2 looked like it had plenty of use from the previous owner so that is one thin that I didn't adjust - i'll definitely use both your references when I install the new one, cheers guys.

It was good to see 4WD on a 1/5th though, even for a limited time - it's gonna be fun.

[mynameismud76]

Think I'm gonna loosen it back up..I only cranked it down to 7/8 mm trying to get more steering response.

The good thing is Mexx, Nutech parts are not expensive at all!:punk:

Well, next to stock parts, alloy bits look real steep =(

Sounds like you're having fun though =)