Upgrading diff due to clinking...

WoodiE

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I was out running my FG Monster Truck this morning when I heard some clinking from the back end of it. Pulled it up next to me and noticed that all four screws on the diff where backed out and the diff casing had a few minor scratches. Since I've got to dissaemble it to fix the screws anyways I figured I'd go ahead and upgrade the diff using the instructions in the FG MT differential upgrade article.

These are the parts I plan on buying from rcnutshobbies.com:

Alloy differential - $74.00
Stainless steel diff case - $17.00

Will there be anything else I need for the new diff? Gears, bearings, anything?




-Michael
 

WoodiE

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Ohh I didn't realize there was more to that article. What type of silicone are you using?


As for the alloy diff holders, probably not going to happen this time around as my budget doesn't allow for it.



-Michael
 

goldencivic

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WoodiE,
First, make sure that Mike at RCNUTSHOBBIES has the parts in stock BEFORE you order. He has been having problems getting stuff from distributors.
Second, there was a discussion about diffs in another thread about Elcon vs FG and the ball drive system. I ordered it from RCNUT and it is part #9472. It is supposed to be better than the stock dogbones. I had the same problem with the screws on the diff gear backing out. I didn't catch it until it had backed out and hit the chassis at some break neck speed and snapped a diff cup which is why I upgraded to the ball drives. But, I figured while I was in there performing surgery, that I would put the Stainless diff cover in and so far so good. I haven't run the ball drives long enough to report on them yet, but they do seem stronger than the stock dogbones. Hope that helps out some.......
 

Badass42

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I Just upgraded my diff to a alloy diff in my smartech bigfoot as the plastic one broke on 1/2 tank with my new motor.

Yesterday I ran 1 tank trough my truck and I noticed the new drive cups I just installed in my new diff were already showing wear.

Is anyone using the ball drives on a MT with a strong engine? If so, are they holding up to the abuse?
I need to go with something better as the drive cups on the diff suck! for some reason the ones on the wheels hold up much better.

Has anyone come out with a CV type drive for these trucks yet?

Randy
 

WoodiE

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Randy,

I've yet to find a CVD setup for the any of the FG models, though I could be wrong. Only upgrade I'm aware of is the ball drive system.



-Michael
 

MONAROMAN

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I don't know how long this has been around for, its listed in the may 07 FG newsletter so I'm assuming its new but its called a "diff key" - does the same as the silicone trick, just got a price of FG importer in aus and $4 AUD, they also have a "hard plastic" diff case but I think the stainless ones would still be better here's the link http://www.fgmodellsport.com/fg-news-pdf-download/News2007/News010-07-empfVK.pdf
 

WoodiE

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Monaroman,

Nice find - though I haven't found any US retailers that have this item number yet.


-Michael
 

MONAROMAN

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Darn, the australian distributor just got a shipment last week - its not in their price lists yet either as its only new - I enquired by email, I reckon somebody's gotta have them in the states... if not let me know and I can send a few over if they turn out to be good
 
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Rex

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I have been running with Ball drive on my FG Leo for the last 2 years.
No problems, Engine is now running with a DDM Race ported 29cc top and a Samba Leop pipe.

I have recently upgraded to the Elcon reinforced XL Ball Drive axes.
They are a bit thicker than the FG ones, and made of a higher quality steel.
I made this upgrade, as I changed to the Elcon XL Rear amrs, that are around ½" longer than the standard arms.
 

WoodiE

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Ok guys I got the FG 8484 alum diff housing in today, however the end where the gear goes is square and not round, plus is to large for the gear to even mount. I thought it was a direct replacement for the stock housing?

What else is needed to get this one to work? Or will it even work for the FG MT?



-Michael
 

Bigger the Better

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I Just upgraded my diff to a alloy diff in my smartech bigfoot as the plastic one broke on 1/2 tank with my new motor.

Yesterday I ran 1 tank trough my truck and I noticed the new drive cups I just installed in my new diff were already showing wear.

Is anyone using the ball drives on a MT with a strong engine? If so, are they holding up to the abuse?
I need to go with something better as the drive cups on the diff suck! for some reason the ones on the wheels hold up much better.

Has anyone come out with a CV type drive for these trucks yet?

Randy

Call or email Duratrax, I have had them warranty a set myself. The Duratrax ones are cheaper in $$ but ,I think they are softer then the Fg's.
 

WoodiE

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Turn your spur around and mount the flat side of the spur to the inside of the square end of the diff housing.

Randy

I didn't even think about that. Thanks!


Problem number two now. I've got the gears into the new diff housing as well as both out drives however when I try to insert the middle pin one side will go in just fine when pushing it on through it won't line up with the other gear for anything. It's always just enough off so that the pin can't go through. I've tried putting the pin in first and then the out drives. Same thing really, one out drive will go in fine the other will not - it's just off by a tiny bit.

BTB did you have this problem with your rebuild?



-Michael
 

Badass42

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I never had any problem with the gears lining up in the diff housing but I did think I had a problem when I went to put the spur on like you did, but I figured that one out.

I did notice I had to put a lot of shims in mine to make eveything nice and tight though.

My housing is not a FG housing either I got it from Germany and it was made for a Carson which is the same as a Smartech, firehammer etc..

Randy
 

allanach

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I didn't even think about that. Thanks!


Problem number two now. I've got the gears into the new diff housing as well as both out drives however when I try to insert the middle pin one side will go in just fine when pushing it on through it won't line up with the other gear for anything. It's always just enough off so that the pin can't go through. I've tried putting the pin in first and then the out drives. Same thing really, one out drive will go in fine the other will not - it's just off by a tiny bit.

BTB did you have this problem with your rebuild?



-Michael

Your gears are not aligned properly if you are just one tooth out it will nearly work but not quite..... You need to pull them out and try again.

I have never done this personally but I have watched someone else to it and we had the same problem until they were meshed properly.

Sorry I don't have any tips but thats what the problem is.
 

WoodiE

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allanach,

Well I took the gears out again and this time did what the FG MT differential rebuild said to do and that was to mark the gears. After doing that aligning up the gears, and reassembling the gears everything is just about perfect. I need a lot of shims for the smaller gears but at least now they are in and looks good.

Should have the rest of the parts by the end of this coming up week and hopefully back on the road by next weekend!




-Michael
 
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