fiveinarow

Bought a new LST last week. I used to race RC10's in the dark ages (1987-88) but that was electric and this is my first nitro car and as we all know the LST manual leaves a LOT to be desired!!!

The truck started up out of the box, ran great on the first tank using factory settings. I took it easy, ran it rich and let it cool off. The second tank ran great in reverse but seemed to lack much power and acceleration in forward. In fact it got where it could barely pull itself forward by the end of the 2nd tank.

I checked the clutch springs and they seem fine. I also adjusted the slipper, tightening it from about 1 1/2 turns out from closed down to about 1/2 turn down from closed. Now the truck WILL NOT move forward at all- just revs. It still runs great in reverse.

Thoughts? Ideas? I'm at a loss but admittedly don't know much about nitro drive trains, clutches, etc.

Thanks in advance for any help,

Steve

ThermalRD

If it only revs in forward, then its not the slipper. So we've eliminated that much. Same goes for grub screws on the cvds, or drive cups. Cant be them either. It would have to be a loose flywheel nut, or a damaged tranny. I would guess that your forward, reverse setup on the radio is wrong, and its not fully engaging the forward gears. I've already walked several people thru fixing that. take the truck, start it up, and put it up on blocks. Manually move the forward/reverse arm to the forward position, then give it some throttle. I bet it works. Once you find thats the problem, then set the radio properly. Im sure it will need the 3rd channel changed from linear, to 2P, and set the EPA on it.

Matt

CRSMP5

i say open up the tranny.. something sounds improper with the claw that changes forward to rev is your rev works just fine..

fiveinarow

Thanks for the input guys. Neither of you took into account just what a NEWBIE I am at this!

I checked the servo- seemed fine. Pulled the transmission and split the halves and *THEN* noticed that the Hi/Lo range was somehow INBETWEEN Hi and Lo. Do that and it runs in reverse but not in forward. DOH!!!

So... I firmly clicked it into Hi range, reassembled everything and it runs like a striped-a** ape: frontwards, backwards, sideways, upside down, YEEHAW!!!

One minor problem now but I'll work it out. Somehow in the R&I of the transmission I fouled up the brakes so there aren't any now! [:@]

Servo and linkage move but nothing happens- but THAT I can fix.

Thanks for the help guys,

Steve

hispeed6

Thermal,

I was (and still am actually) having just about the same problem. Initially I thought that my one or two slow roll reverse-to-forward shifts had caused the gears in the tranny to not mesh properly. So, I split my tranny and checked for damage. Both the forward and reverse engagement dogs looked good-as-new. The only thing I noticed that was out of the ordinary was a little binding between the plastic cylinder between the lever arm on the outside of the tranny and the shift fork on the inside of the tranny. I lubed it (the plastic cyclinder) up and re-lubed the tranny gears while I was in there, still no joy on shifting from reverse to forward. It's easier by hand for sure but still won't shift with the radio. Until I read this post I was pretty sure I'd messed up that cylinder or somehow created too much play in the mechanism for the shifter to work. That is, until I came across this thread!

How much did you adjust your endpoints on you shift servo? Did you max it out for the forward direction? Thanks!

fantomas

My Feedback: (3)

i have mine 40% forward 100% reverse, but im sure that is a little give and take.. sorry i had those backwards! its correct now...

ThermalRD

When i adjusted the EPA on my For/Rev servo, i checked for play, and watched the metal ring on the servo horn for bulging. Start with one direction first, increase til you see the ring bulge. That means you are applying pressure, to the point the metal ring starts to spread. Push on the rod a little in that direction and make sure there is no more room for it to move. You want it fully engaged, but not with alot of stress on the servo. Thats referred to as holding power, and eats batteries a bit faster. Do the same for the other direction.

Matt

fantomas

My Feedback: (3)

yea and to be honest you can only go so far in the forward direction... my servo dosent buldge when its in forward.. just a little when i put it in reverse.. i could set my epa back a few points in the reverse, but i hardly use reverse, but when i do i want to make sure its fully engaged

creyc

For EPA my AUX channel is at 44% for reverse travel and 76% forward travel. I get smooth shifts every time and there's no possibility of it bouncing between gears. Setting it to 100% would definitely cause my servo to be under constant load and I find that unnecessary and generally an extra battery waster and more wear on the servo. At my EPA settings there's just enough pressure to keep it surely engaged in forward or reverse but not extra travel to try to push the arm where it won't go. After all, there's no backwards pressure being pushed against the servo, all it has to do is keep the lever in place.

When I was first using AA power mine would glitch to the point where it would kinda float in between forward and reverse. After realizing how dangerous an accidental shift to reverse while at speed (either from user error or radio glitch) I decided not to fool around with weak batteries and promptly bought a flat pack to fit underneath. It was at that point I also adjust the EPA and I've not had troubles since.

fantomas

My Feedback: (3)

ok i just went and looked at my truck and i noticed that when i shift at a stand still my shift lever dosent engage all the way, but if i just move the truck a little bit it engages...hmm i never noticed that before! has anyone else noticed this??? i havent had a problem with shifting out of forward or reverse but thats when the trucks running...

fantomas

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oh yea it dosent matter how i set the EPA..

creyc

There's a very simple explanation for why it doesn't engage immediately. Tearing apart the transmission will illustrate why this is so, but hopefully my explanation can do the same but without the grease on your fingernails.

So by now I'm sure you know how the shifting is accomplished on the LST, both for reverse and HIGH/LOW, it's the same mechanism. By sliding the drive axle off to the left or right it comes into contact with a gear on each side. Simply pushing two pieces of metal next to each other creates little friction and doesn't provide a very good system of locking the axle to the gear so Losi added notches in the two pieces that, when aligned correctly, mesh with each other and lock in.

This causes the drive axle to be fixed to either the forward gear or reverse, but only when the notches are aligned. While the truck is running this works perfectly each time because even if the pegs sticking out of each surface don't align at the time of the shift, the rotation of the drive axle means that within less than a quarter of a full rotation later the four pegs will line up and the axle will be locked firmly against the gear. It "snaps" into place very quickly while the truck is running and as long as the condition of the four pegs is good the shifts will always be sharp and positive. When you shift into reverse without the engine running or the wheels spinning there's a good chance of the pegs not perfectly aligning at the precise time you hit the button. They are overlapping and waiting for the rotation of either the wheels to move the gear into place or the engine to turn the drive axle into place. By simply pushing the truck forwards a few inches it should be sufficient to align the pegs between the two surfaces and complete the shift.

It may sound complex but it's a very simple system that works amazingly well. In fact it's long since been used in full-size car transmissions because of its durability and ease of shifting. I'm impressed Losi decided to use this setup for every type of shifting done on their new truck. In comparison with something like the T-Maxx transmission it's clearly the way to go; all shifts are precise and you get a smooth transfer of power to the wheels, regardless of the throttle position or engine speed. If you've ever seen the jerky acceleration at very low speeds on a T-maxx you'll know what I'm talking about.

If you need a better mental picture of the way this system works, it's better to just tear your transmission apart and play around with it yourself. And of course there are pictures someplace on this site of the innards of the transmission, those can help.

fantomas

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lol.. so im ok!

creyc

in short, yes

fantomas

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ok since we are on the subject of the tranny... take your truck and push it (while its not running) kinda hard then fully apply the brakes.. can you tell me what that clicking sound is?? is it the brakes or the tranny? i know its not the diff..

fantomas

My Feedback: (3)

for more helpfull tips go too http://www.lstcentral.com/

creyc

It's the metal brake pads chattering against their metal calipers. Also normal.

And I may have my brake adjusted too sharply but if I do what you said, and fully apply the brakes, there's not really any chattering but the truck just STOPS! If I partially hold the brake while pushing the truck I definitely hear the noise you're talking about. You only hear it on this truck because every part of the brake system is metal. It's quite normal though, even if it does get annoying.

fantomas

My Feedback: (3)

sorry for hi-jacking this thread this will be my last post on this subject ..lol yea i have posted before about the brakes chattering and people shouldnt confuse this with the diffs, but i just wondered if anyone else agree'd with this brake theory...

jefx

Yes, mine does this as well, but it also has a hard time shifting between the two while running.

When I shift it when it's not running, it won't engage untill it's rolled a few inches, then snap, it's in place.

Now when the engine IS running, and I switch from forward to reverse, the tranny stays in forward for a while. I can see the servo ring bulging as it's trying to get the tranny into reverse but it doesn't go there. I have to give it throttle and it'll continue to go forward, then I come to a complete stop and then give it more throttle again. I have to repeat this process several times before it'll finally snap into reverse.

The same is also true for reverse to forward shifts. Why is that? And does that happen to anyone else?

ThermalRD

Nope, mine shifts without problem. If this is something that is caused over time, and alot of use, then mine certainly wouldnt show the wear yet. I dont use reverse that often at all.

jefx

Me either. I've only engaged it maybe 5 or 6 times since I've owned the vehicle. I try not to use it since it doesn't work all that well. It worked perfectly when I got the truck, the first couple times I tried it, but now it takes forever for it to engage.

fantomas

My Feedback: (3)

i dont use reverse alot about the same as you jefx, but i dont have a problem with it engaging while im running it always goes right into forward and reverse.. it just gives me the problem when the trucks not running and when its at a stand still.. im sure mine has been like this for awhile but i just never noticed it before.. well later when the wife gets here i will go fool around with it..

ThermalRD

Well, i readjusted my brakes, so they are a little stronger now. Im getting that clicking again. I will check my diff cases after i've run this battery dead.

fantomas

My Feedback: (3)

LMAO!!

icenutz

I have the same issue in regards to the shifting and the brake clicking. My shifting also worked perfect when I first ran the truck but now there is and occasional problem. That clicking on the brakes, normal or not, it does not sound good. It makes me want to back off the brakes to avoid problems. Even when I raced yesterday, I was fearful the entire time and hesitant on my driving. I still beat a Revo, 2 Tmaxx's, and a Savage, among others to take first after three 15 lap heats. I can't wait for these issues to be resolved and a few choice upgrades to be added. I can't image how these races would end up if I was able to not hold back.


This is very interesting to read all of this. I haven't had time to check mine out but all the symptoms you have stated I also have. Keep posting and thanks to all for the info and resolves.