2 speed problems?

[Paul11277]

Hi, I took my t maxx out tonight after a few tweeks to the suspension last night. The past few times i have had it out have just been in the street. But tonight i wanted to see if the changes i made to improve the handling at speed had worked so it took it to a massive car park. After a few small passes just to get the engine warm i noticed that it was not shifting gear. So i adjusted the gear change 1/8th anti clock wise to make the shift come earlyer. Nothing changed i did this 3 or 4 times and nothing changed so i gave it a full turn in the opposite direction to try make the shift later just in case it was stuck in secong gear. Yet still no difference. The truck was jerking forward on idle so i adjusted the idle and that hasfixed that problem. But could i have just masked my real problem in regards to my 2 speed not working.

Are there any simple tests i can do to check my 2 speed. I am sure it is stuck in second gear but if its not then i can't wait to see just how fast it goes if i get the thing to work properly.

Hope you can help please ask for any info you may need.

 

[Rolex]

You do not have a trans problem.
The idle needs to be right, and so does the tune. Make very minor adjustments and keep testing. When it shifts regularly, then you adjust the trans to set the shift point earlier or later.

 

[olds97_lss]

Could also be your slipper slipping so your not hearing it shift.

Does it seem to have a slow top speed? Is it really sluggish off the line?

 

[jon2]

The truck was jerking forward on idle so i adjusted the idle and that hasfixed that problem. But could i have just masked my real problem in regards to my 2 speed not working.

Are there any simple tests i can do to check my 2 speed. I am sure it is stuck in second gear but if its not then i can't wait to see just how fast it goes if i get the thing to work properly.

Hope you can help please ask for any info you may need.

The jerking you mention is also common to the TMAXX Tranny. It may just need more breaking in. How much fuel through it? The more you drive it it will settle in and the jerking will become less noticeable. As far as what has been said, let me add that the tranny will not shift unless it reaches a certain RPM. This allows the tranny to be properly used so there is enough grunt in the lower RPMs allow it to shift. This works alongside how you set the shiftpoint.

 

[Paul11277]

2 speed

HI, No i dont hear it shift its not quick of the line but i wouldnt call it slow. It wont pull a wheelie of the line but it does take the weight off the front end thats for sure. I would not say it has a slow top speed either although i do need a good 120 meters to reach top speed.

The reason i think the 2 speed it faulty is because it did work fine when i had my .15 engine. I swaaped engines but never really took it any where with enough space to notice the gear change before last night. If it is stuck in a gear i am sure it must be 2nd because it really is fast but it its not as fast as it used to be off the line. I would pop a wheelie in the past not every time but it was always possible with a little effort.

I have played with the slipper clutch. Presuming this is the nut on the front of the spur gear. But i can't find any real details on how it should be set so its all trial and error. I have to be honest though that did not seem to make any difference either. Ojne thing that may be worth noting is that when i replaced my 72 tooth spur i did put 12 pegs in instead of the original 6. Though this made sense with me putting a bigger engine in. I really dont think its a mixture problem i dont think it could rev much harder than it did lastnight without going to 20% fuel. :surrender

Hope this helps.

 

[jon2]

Really sounds like it it is stuck in 2nd Gear. If it was stuck in 1st, it would rev high fast but nothing more. Try taking apart the tranny and make sure the 2 speed is assembled right. Traxxas has the proper instructions for you.

 

[Paul11277]

Well i have had a look at the instructions and it looks like it could be a long and complicated job. Think i might have a go at making the shift later just incase it is an adjustment. I have never moved the shift point not even after swapping engines so it could be just shifting into second instantly. Maybe I'm wrong and am still going to have to strip it down. If i do strip it down is there any kind of upgrade worth doing while i am in there.

 

[Rolex]

It happens that the shift point changes without notice. I once had mine hit second almost as soon as it left the line. I don't think it got 2 feet.
When you changed the 72 T spur, what did you go to?

 

[Paul11277]

Spur gear

I changed the 72 tooth that was on there for a 70 and fitted my new 2.5 engine at the same time. But been a novice i took one gear off and put the new one on but with no pegs. Needless to say what happend. So i decided i would go buy some new pegs and another 72 tooth gear when i noticed the pegs in the old one. So i explain at the shop what i was doing and he said fit 12 pegs instead of the standard 6 and tighten it up as far as you can. I did all this with everything still on the chassey apart from the engine of coarse.

I know no better so thats what i did. Is there a method to setting the slipper clutch. I am still a novice when it comes to some of the finer details although i have rebuilt my t maxx from nothing when i swapped the chassey. The local shop isnt really an r/c car /truck dealer he deals in airplanes but does stock some of the more common parts. But that makes me think that his advise maybe wrong.

 

[Rolex]

That's what I had. I went from 72 to 70, and on the track I was running on at the time, it was amazing. You'll get a slightly slower takeoff, but a good top end.
It's cold out. Don't expect it to act the same as it did on a good day. Put the cuff of an infant sock or tin foil around the cooling head to get the engine to proper running temp.
To set the slipper, tighten it all the way, then back it off about a quarter turn.

 

[Paul11277]

I have done what you said with the slipper clutch. Will let you know the result when i take my truck out. I have to wait for a new fuel tank to arrive now because mine has a crack in it. I have tried fixing it with epoxy resin but a couple of tanks of fuel and it just pealed off. Have done it with aqurium slicone now see how that holds out while i await my new one.

Thanks for your help on this guys. I am sure i will be back on this subject once i get a chance to try everything out.

 

[olds97_lss]

Like what was said, it's probably hitting 2nd so quickly that you don't realize it. Try adjusting your shift screw CW. Also, instead of hammering it off the line, go really easy on it and see if you ever hear it shift.

 

[Paul11277]

2 speed least of my problems now.

Hi All. Well whilst trying to get to the bottom of my 2 speed problems i crippled my T MAXX. Well it looks bad anyway, but its not i have demolished the front bulkhead thats all. The diff and everything else has survived.

But i got to the bottom of my trouble, its now just a case of tunning to get it out of the first gear. My shift point was like i thought and many of you guys agreed very early. The noise i mentioned earlyer in the thread was actually the gear change but because of the such low revs it was changing at the change sounded more like a faulty gear box than a change.

So i made the shif half a turn later and its almost perfect just need a little tunning and a new bulkhead and i should be there. I have not ordered my bulk head yet because i am toying with the idea of getting alloy ones. So far where possible and financially viable i have replaced plastick with alloy. Bulkheads are very expensive though in the uk. But i do have a bid of $16.00 us dollars on an alloy pair on ebay. This would be a tiny fraction of the cost if i was to buy them in the uk.

If anyone has any for sale or knows where i can get hold of them at a reasonable please contacts me. New or used i dont mind. Please be aware that i am in the uk.

 

[olds97_lss]

Glad to hear you figured it out!

FYI, the 3.3 grey bulks are supposed to be tougher... not sure if that's true or not. I run ACNCM bulks the majority of my 3 years with a maxx. I tried integy's, but their stuff bends and strips out very easily.

Great Assembly makes some of the best bulks you can find for a maxx: http://www.greatassemblyrc.com/Store_Detail.cfm?ID=114486&InfoID=3573
$105 US, but looking at their site, it appears they will ship internationally if you contact them via email. I know it seems like a lot of $, but for the full set of bulks and nice aluminum braces, they are worth every penny. A buddy of mine bought them about 4 years ago and I was in awe... if I had stuck it out with a maxx, I would have bought them as well. They use 7075 aluminum (the hard stuff) for the bulks and I believe they use helicoils for the threaded portions for the skid plate. Much tougher and hold up to being taken apart frequently.

If you do go with aluminum ones, most (if not all) require that you get different hinge pins that are held on with e-clips. Keep that in mind when your buying.