FG MT - Loud Grinding Noise

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sperera

sperera

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Got a loud grinding noise coming from the MT. Sounds perfect at idle, as soon as i give it some revs and it starts to move there is a very loud grinding noise, so loud I can hear it over the DDM pipe!

I thought it was the clutch at first so I pulled apart the clutch bell, shoes look almost new, even wear, no play, no marks on inside of bell. I am missing one tootch off the ring gear that sits on outside of diff. thats been missing for a while, have ordered repalcement and also the small gear that sits on layshaft which this gear meshes with because its showing allot of wear!

Im thinking maybe one of the bearings on the layshaft has let go, is there supposed to only be 2 bearings on the layshaft? The layshaft is what the brake disc sits on yeah?

Its got me stumped. I really don't think its the engine because it sounds fine at idle.

Any idea's?
 
Hold the model down or against the wall. Throttle up to see what is spinning. i would say your either skipping the laysaht to diff gears or you have lost a grub somewhere.
 
I had that on my Marder & it was layshaft gear. Plastic engine mount was knackered & wouldnt tighten up properly allowing layshaft & diff gear to separate slightly. Check your engine mounts after every run out to ensure they are still tight. Screws might need nipping up from time to time & make sure they are thread-locked!!
 
BTB,Soop and Dwarfy are right! You have the plastic diff holders and the screw on the top has either come loose or has pulled its thread. Get an oversized screw and wind it in when the gears are meshed properly or go all out and buy alloy engine mounts and diff holders.
J.
Oh,get shut of the alloy diff brace there crap.
 
All I can think of bud is the amount of wear on the pinion has opened up the pitch,,,,(the distance between the teeth),,,,so no longer matches the diff gear.

It would be like running a 32 pitch pinion on a 48 pitch spur on an electric car.

Your pinion is very very worn,,,,to the point where you would say it is f***ed!
 
Rossco said:
......Your pinion is very very worn,,,,to the point where you would say it is f***ed!
Click to expand...

Thats what eventually happened to mine but it was caused by the engine mount moving cos the screw hole in the plastic was shot. With the correct mesh the gear wont wear on the top edge of the teeth which causes the slip.
 
got the layshaft gear and the ringgear today, stuck with FG parts, was going to go to oversize rc and try smartech stuff but ive been there everyday now for the past 6 days and they arnt open, even though they have a big sign out the front saying open and their hours indicate they should be.

also got 2 bearings for the layshaft, according to PSR there should only be 2 on there.

should get some time later in the week to install these, will see how I go, might need some help when you get up here Rossco :)
 
LOL ull have to bring your camera up with you, I like the other track heaps more, so much more grip and its bigger!

Hopefully I will have the FG together before you come up, not sure I can handle 2 weeks without it LOL.
 
sperera said:
got the layshaft gear and the ringgear today, stuck with FG parts, was going to go to oversize rc and try smartech stuff but ive been there everyday now for the past 6 days and they arnt open, even though they have a big sign out the front saying open and their hours indicate they should be.

also got 2 bearings for the layshaft, according to PSR there should only be 2 on there.

should get some time later in the week to install these, will see how I go, might need some help when you get up here Rossco :)
Click to expand...

You spewed the ring as well? Oops,thats gotta been a bad mesh,your engine was on a slant then? When you install the lay gear make sure you line it up with the ring,if its not going to line, Dremmel the holes in the mounts(chassis,you will only have to take 1-1.5mm off)
Good luck
J.
 
im going to do it all in the workshop here at work tommorow night after work. all the tools I could possibly ever want or need :)

just to confirm when im meshing the layshaft and ring gear tommorow there should be about 2mm of play?
 
can happen fast. I have a layshaft gear and ring gear here I used until a set came. had to file the teeth just to make it work. you could hear that horrible sound in one of my semi vids hehe

glad you got it sorted out at least... shoe goo under the motor mount and in the screw holes if it's plastic... I also made a brace that comes off the motor and onto the back plate. with the brace I can remove the motor mount screws and the gear stay together... save to some headache and easy to make. just need to do a little bending of some aluminum
 
ill try and keep the play to a minimum in that case.

i know from new there was quite a bit of play in there, didnt seem to be much of a problem but that might be the reason why thay layshaft gear has worn within 8 litres of usage.
 
Use a business card or better yet use the cardboard piece from the bag of your new gears. That will be the right mesh. Push it tight then roll it out.
 
awesome, sounds easy enough! I should have it all back together unless I run into problems like I did yeasterday.

when putting the brake disc on the layshaft. there is the square block that the brake disc sits on which rotates it when the wheels are moving, from what I can tell the only thing that holds the disc from falling off the block is the fact that a part of it rotates within the 2 metal brake pads. Is this all that holds the brake disc in place? Id be surprised if it is. :helpsmilie:
 
I am lazy. I tip it so back wheels are down, loosen motor mount screws and then roll the rc a bit and tighten. double check when flat. usually gets it pretty close each time. then I drilled out that brace. never had a problem since
 
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