Please help. LOUD CLUNKING SOUND

[bugman]

:helpsmilie:Hi folks,have just joined today and would really appreciate your help.I'm also a newbie to 1/5th trucks. Anyway i took the truck out yesterday which is only about it's 3rd run for me as i bought it second hand and after about 20 mins it started to make a nasty clunking noise when putting the power on.Stupidly i kept runnig it and now all it does is make a metalic shearing noise with hardly any drive although it will creep forward by just blipping the throttle.Are there any step by step instructions on how to remove the engine and all the other associated bits and bobs so as to get at the diff.It's got an O'neils 30.5cc with jetpro pipe,but i don't know what mods it's got until i can pull it apart but still won't know what i'm looking for.All i know is the previous owner has chewed most of the allen head bolts up and had the failsafe set to brakes off and 100 percent throttle.Scary or what.Still can't understand how he managed to do that but there you go. Sorry this is a long one but once again guys any help will be much appreciated....bugman

 

[dc2 man]

locate problem

hello bugman

i think you need to check all pinions first to make sure they are tight,get the correct hex/allen key and make sure they are all good and secure on all gears,check and rotate everything up on a table to make sure nothing is binding,from listning to your truck this way you should almost hear where the problem is,now if all the above is done and problem still persists then as follows...

well if above has failed then i think your problem very well may be your rear differntial.

you do not need to remove engine for this job.

also the screws you just need to take the time and get them out without damaging anything else.

how you check it is as follows.take off two rear wheels,unscrew top hub/balljoint long screw at either side,remove drive shafts both sides,unscrew shocks at the bottom both sides,then unscrew four securing chassis screws unerneath.

after this common sinse should show you how to take out the diff from the mounts,it really just pulls out with small bit extra ripping.

now you don't have to strip actual diff at all because what i think the problem may be is the diff gear slipping on the diff casing,if this is the case you will notice the problem straight away.

what this means is the big diff gear is screwed to the diff casing with four screws now either the diff gear has ruined the casing and pulled through from screws or screws may have just came loose.

now if either of these is what has happened
1/ if screws have came loose retighten with blue threadlocker and reassemble everything back like i told you how to rip it down
2/if the diff casing is ruined you either need to order a replacment or upgrade to an alloy differential casing and mounts also optional,would be better to get alloy mounts also if you decide the upgrade version.

here is what you will need either of these ahead you may choose.
first check out whay i have suggested and get back to me.

http://www.rc-car-online-shop.de/cg...84&file=&gesamt_zeilen=0Tsuche--fg alloy diff
also you may need these.
http://www.rc-car-online-shop.de/cg...02&file=&gesamt_zeilen=0Tsuche--fg alloy diff

all your own diff parts will go directly on this new one,such as internal gears,diff cover etc etc...

let us know first what the problem is and we will help some more..
best of luck.

 

[Super654]

Post up some photos of the rear end for us mate..

 

[bugman]

Hi dc2man, and many thanks for the swift reply and detailed help. I'll start to strip it down later and let you know the results. What i can see of it at the moment, it's the bog standard plastic diff mounts and i suppse will be the standard diff as well. Will buying these 2 alloy upgrades make a huge difference. Also if you don't mind me throwing another question at you, i tried to tune the carb on the engine as the engine slightly bogs from a standing start, but the midrange and top end are great. I started with the basic settings and tried to tweak it from there, but am still unable to get rid of this flat spot. I've seen them on youtube with a basic 26cc Zen and are popping wheelies pretty much from a standing start. Surely my O'neils with a pipe should blow that away. I guess i'm pretty disappointed with it's wheelieing capability but i still love this truck. Any ideas. Many thanks....bugman

 

[dc2 man]

Hi dc2man, and many thanks for the swift reply and detailed help. I'll start to strip it down later and let you know the results. What i can see of it at the moment, it's the bog standard plastic diff mounts and i suppse will be the standard diff as well. Will buying these 2 alloy upgrades make a huge difference. Also if you don't mind me throwing another question at you, i tried to tune the carb on the engine as the engine slightly bogs from a standing start, but the midrange and top end are great. I started with the basic settings and tried to tweak it from there, but am still unable to get rid of this flat spot. I've seen them on youtube with a basic 26cc Zen and are popping wheelies pretty much from a standing start. Surely my O'neils with a pipe should blow that away. I guess i'm pretty disappointed with it's wheelieing capability but i still love this truck. Any ideas. Many thanks....bugman

no probs at all man.glad to help you if i can.

yes these upgraded are essential on the monster model,but only if you need them,check first like i said to see if the diff is the problem.

where did you buy the truck?

o neills are very good but i suspect you have the wrong carb,im guessing you have the standard carb like me,if you run the proper carb on that it will blow you away man.

this is the correct carb for that engine.

i also have an upgraded lauterbaucher intake manifold which also helps.

here is the carb you need it should be the walbro wt 771. you have the standard 813 one the i would think.

http://www.rc-car-online-shop.de/ls...vergaser,y1066,,Tshowrub--motor.vergaser,.htm

 

[Bigger the Better]

Start the truck. Hold it against the house or in place so it cannot move. Throttle up slowly and look to see where you are loosing the power. If you hold the truck down and against a non moving object you can find out what is not working.
One of these is broken. We can only hope you spun a wheel square.

1. Gear from motor (Pinion) moves.
2. Large gear (Spur) moves.
3. Spur shaft moves spur gear in back of motor area.
4. Spur shaft gear moves differential ring gear.
5. Ring gear moves differential.
6. Differential moves out drives.
7. Out drives move drive shafts.
8. Drive shafts move drive axles.
9. Drive axles move wheel squares (aluminum blocks on shaft).
10. Squares spin tires.

 

[bugman]

Think i've found the problem

hello bugman

i think you need to check all pinions first to make sure they are tight,get the correct hex/allen key and make sure they are all good and secure on all gears,check and rotate everything up on a table to make sure nothing is binding,from listning to your truck this way you should almost hear where the problem is,now if all the above is done and problem still persists then as follows...

well if above has failed then i think your problem very well may be your rear differntial.

you do not need to remove engine for this job.

also the screws you just need to take the time and get them out without damaging anything else.

how you check it is as follows.take off two rear wheels,unscrew top hub/balljoint long screw at either side,remove drive shafts both sides,unscrew shocks at the bottom both sides,then unscrew four securing chassis screws unerneath.

after this common sinse should show you how to take out the diff from the mounts,it really just pulls out with small bit extra ripping.

now you don't have to strip actual diff at all because what i think the problem may be is the diff gear slipping on the diff casing,if this is the case you will notice the problem straight away.

what this means is the big diff gear is screwed to the diff casing with four screws now either the diff gear has ruined the casing and pulled through from screws or screws may have just came loose.

now if either of these is what has happened
1/ if screws have came loose retighten with blue threadlocker and reassemble everything back like i told you how to rip it down
2/if the diff casing is ruined you either need to order a replacment or upgrade to an alloy differential casing and mounts also optional,would be better to get alloy mounts also if you decide the upgrade version.

here is what you will need either of these ahead you may choose.
first check out whay i have suggested and get back to me.

http://www.rc-car-online-shop.de/cg...84&file=&gesamt_zeilen=0Tsuche--fg alloy diff
also you may need these.
http://www.rc-car-online-shop.de/cg...02&file=&gesamt_zeilen=0Tsuche--fg alloy diff

all your own diff parts will go directly on this new one,such as internal gears,diff cover etc etc...

let us know first what the problem is and we will help some more..
best of luck.

Hi, great instructions dc2man. I managed to get the diff out and i think i've found the problem. After some careful inspection of the pinions and seeing plenty of metal filings inside the chassis i noticed that the layshaft pinion has got a couple of chipped teeth and the rest are pretty mishapen. Looking further showed up all the engine mount bolts had come loose, Doh!!!! which i'm sure is what must have caused the clonking sounds as the gears obviously weren't meshing properely. I also found that the exhaust manifold was very loose but it didn't show before because the pipe was tightly bolted to the gear carrier. Also talk about coincidence, i was searching the forums for pinion/spur gear sizes and who should i come across but your good self dc2man, and guess what, my layshaft pinion is also a 16 tooth, which may well account for the bogging down, coupled with the loose exhaust header. Thing is i don't want to loose too much top end. Do you think changing to the 14 tooth layshaft pinion will cure my bogging down problem without loosing too much top speed and give the truck the wheely popping low down stomp that i want. One other problem is i cannot get the grub screws out of the layshaft pinion because if i use any more force i think i'll chew the heads up. I think the previous owner must have loctited them instead of using threadlock. Would heating the pinion help? otherwise i don't know how i can remove the pinion. Does anyone know how to tell what model my carb is. All i can tell you at the moment is the carb looks very similar to some of the other walbro carbs but mine has a red choke lever. dc2man and all you guys out there all this help is much appreciated. A member for only 1 day and already i cannot believe all this help i'm getting. This place rocks. Thanks again guys. P.S. Great elimination process Bigger the Better. I'll use your method in the future. Many thanks for that....bugman

 

[dc2 man]

lets sort this....

i think you need the correct tool to take off that pinion what are you using?

allen keys are week enough and cannot apply the correct torque,i use hex wrenches from hobbythek,they are excellent..
here is apic of what they look like.
http://www.rc-car-online-shop.de/ls...rk1,tool_0026,,Tshowrub--werkzeuge.werk1,.htm

what i would do is take out engine ok,take off large engine mount with layshaft attached,and take out your layshaft out of your gearplate.

to do this you just need to unscrew two screws from under the clutch casing attaching large engine mount to engine also the four screws under engine on chassis.

this will give you more room when you have the l/engine mount and layshaft out on you hands,now if you have access to a vice you could hold the layshaft in there to get the right torque to open the grubs,once out throw them away and replace with new ones.

now question you asked about pinion,you do need the correct pinion on that layshaft which is a 14tooth.

the correct pinion and spur is as follows
clutch=16
spur=48
layshaft=14
diff=48

this is set up from stock leaving factory and it is the best choice,now the reason a 16t was on your l/shaft was for a better top speed but killing your lowend.

your carb is most likely the stock one the walbro 813 wt there should be numbers marked on it somewhere,i wouldnt worry too much about that for now though it will run grand but just could benifit better with the 713walbro wt as it is a big bore o neills.
i would eliminate all the above first and get your truck running with the 14 tooth l/shaft and see how it goes.

one step at a time.

best of luck bud.

 

[Bigger the Better]

After some careful inspection of the pinions and seeing plenty of metal filings inside the chassis i noticed that the layshaft pinion has got a couple of chipped teeth and the rest are pretty mishapen.

Change both the pinion and the diff gear out. After one rounds the teeth off of the other it will push it away forever.

Do you think changing to the 14 tooth layshaft pinion will cure my bogging down problem without loosing too much top speed and give the truck the wheely popping low down stomp that i want.

Change it out. Worst thing you can change it back but it will help eliminate the bog.

One other problem is i cannot get the grub screws out of the layshaft pinion because if i use any more force i think i'll chew the heads up. I think the previous owner must have loctited them instead of using threadlock.

Would heating the pinion help?

Yes, if you use heat it will melt the thread lock and allow the grub to loosen much easier. If thread lock was used and it made its way to the shaft it will also cause a big stink if not heated to get the gear to spin off. You will have a bit of trouble if the grubs have bitten into the shaft. The marks will raise the shaft slightly and the gear will rub on the shaft. Use a vise grip and spin it off best you can. If the marks are raised just use a file or sand paper to sand flat.
If your allen wrenches are rounded on the end cut a small bit off with a dremel so you have a good end to go into the grub. I find freezing them 1st will help keep them from heating up.

Good luck and welcome to the rebuild part of the hobby.:Laugh:

 

[waqr]

i think you need the correct tool to take off that pinion what are you using?

allen keys are week enough and cannot apply the correct torque,i use hex wrenches from hobbythek,they are excellent..
here is apic of what they look like.
http://www.rc-car-online-shop.de/ls...rk1,tool_0026,,Tshowrub--werkzeuge.werk1,.htm

what i would do is take out engine ok,take off large engine mount with layshaft attached,and take out your layshaft out of your gearplate.

to do this you just need to unscrew two screws from under the clutch casing attaching large engine mount to engine also the four screws under engine on chassis.

this will give you more room when you have the l/engine mount and layshaft out on you hands,now if you have access to a vice you could hold the layshaft in there to get the right torque to open the grubs,once out throw them away and replace with new ones.

now question you asked about pinion,you do need the correct pinion on that layshaft which is a 14tooth.

the correct pinion and spur is as follows
clutch=16
spur=48
layshaft=14
diff=48

this is set up from stock leaving factory and it is the best choice,now the reason a 16t was on your l/shaft was for a better top speed but killing your lowend.

your carb is most likely the stock one the walbro 813 wt there should be numbers marked on it somewhere,i wouldnt worry too much about that for now though it will run grand but just could benifit better with the 713walbro wt as it is a big bore o neills.
i would eliminate all the above first and get your truck running with the 14 tooth l/shaft and see how it goes.

one step at a time.

best of luck bud.

Don`t you mean the 771 carb dc2 man? Never heard of 713 Walbro :blush:

 

[Trip]

Good advice guys!!! A couple notes though, Loctight is thread lock... Use the blue..
The 16 tooth layshaft gear was probably used to keep it from flipping over backward under acceleration. You can switch to the stock 14 tooth, but you will loose some top end speed.

The failsafe sending the throttle to full... Did you switch servos or are they the same servo the previous owner used? I ask because, if you are using Airtronics servos, they are wired backward or opposite from a hitec or futaba. I had this happen on a brand new RTR, I switched to airtronics servos and didn't reset the failsafe. The failsafe went to full throttle instead of full brake and boom, right into a curb!

Trip..