2 Speed Gearbox & Diff Ratios

allanach

Well-Known Member
Messages
388
Location
Brisbane
A standard FG MT has the following gears:
16 tooth pinion
48 tooth spur
14 tooth layshaft gear
48 tooth diff gear

I am thinking of runing the below in a 2 speed:
16 tooth pinion 48 tooth spur
20 tooth pinion 44 tooth spur
14 tooth layshaft gear
50 tooth diff gear

I have the following questions:
This 2 speed combination with diff gear should provide more bottom end and more top end?
Do the normal (single speed) steel gears work on the 2 speed?
Has anyone tried this combination & what do they think of it?

Thanks for your input.
 

fgbasher

Well-Known Member
Messages
200
Location
USA
The 2 soeed gears are different than the single speed gears. Jumping from a 48 to 44tooth may be to big of a change and strip out the gears. You may want to go with 18/46 then 20/44. Are you running a pipe? if you are running stock, it may take a little to get up there with the 18/46.
 

allanach

Well-Known Member
Messages
388
Location
Brisbane
Thanks RC Nuts

Well curiosity got the better of me and now I have a two speed with metal 16 & metal 20 tooth pinions on 48 & 44 spurs.
I also installed a 50 tooth diff gear to replace the 48.
This should give me more torque than stock & more top speed.... giddy-up.
Let you all know how it goes:)
 

allanach

Well-Known Member
Messages
388
Location
Brisbane
As per above, this is my opinion of what this combination delivered.

First gear take off is awsome wheelies on demand no dramas, with the factory 2 speed setting the clutch kicked in and 2nd gear was winding out and the speed is incredible. I had to adjust toe in on the steering as the thing was so unstable, this provided rock solid stability at top speed and didn't take to much away from the handeling (for a MT).
On occasions the front end would lift a little when changing into second gear, this is cool IMO.
On a flat grass surface the MT normally got chewed up by 26cc & 29cc Hpi Baja's and now it mixes it up with all of them and has a top speed of around 80KPH+. This seems like a good combination for now as I do a lot of WOT bashing and I would recommend this set-up "BUT" I managed to sheer of both diff out drives when I couldn't handle the speed and performed end of end rolls at warp speed:(

Would I do it again......... you bet.
 

allanach

Well-Known Member
Messages
388
Location
Brisbane
Well I got rid of the two speed today.... 1/2 a dozen tanks of fuel and the thing just $hit it's self.
The little pin that picks up the clutch finger for the second gear fell out so I drilled a new hole, warmed up the housing, used locktite and shrunk fit a new pin only to find it come out also.

The other problem with this set-up was the fact that nobody sells a gear cover to prevent you from chewing spurs :(

Another thing that annoyed me was the std shelded bearings were starting to feel a bit rough "why don't FG use sealed bearings"?

IMO the two speed may be better on a lighter car as a 3 mm pin is not up to pushing a heavy truck, but man it was good while it lasted......
 

allanach

Well-Known Member
Messages
388
Location
Brisbane
I took the two speed to the HS and he will sell it or even buy it for himself.
In Australia they retail for about $300 - $330 au, but you can pick them up new in the US for about $199 usd.

The combo I was running is very impressive and I would have kept it if it wasn't for the pin falling out all the time.
 

mnorman367

Member
Messages
8
Location
Farminton Hills, MI
I have a two speed with metal gears. My question is what is the first set and what is the second set gears? The inside ones are the initial gears? My outside gears don't interlock when I spin the wheels manually, so I am assuming these engage at the higher speed for the second gear? These seem to get chewed up a bit since when they spin at first the touch just a little and have gotten a bit worn very quickly.

Can anyone clarify for me the operation of the two speed?

Thanks
 

Magnum57

Member
Messages
19
Location
Scottsdale, AZ
the 2 speeds are a pain in the butt. i've tried them and there sweet while they last. big bucks for a short trip. in my fg mt i run a 28/36 from the 16/48 stock gears and holy crap fast if you have enough motor to turn them there sweet. i run a 29cc stuffed and ported reeded motor. i had to change the tires they could'nt hang. lower profile race tires and she will do about 65mph. no more playing with 2 speeds for me. best 50 bucks i ever spent. 65 is plenty fast for a monster truck. hey pep i have a like new carson 23cc i might sell with 2 bodies and extras.
 

allanach

Well-Known Member
Messages
388
Location
Brisbane
I have a two speed with metal gears. My question is what is the first set and what is the second set gears? The inside ones are the initial gears? My outside gears don't interlock when I spin the wheels manually, so I am assuming these engage at the higher speed for the second gear? These seem to get chewed up a bit since when they spin at first the touch just a little and have gotten a bit worn very quickly.

Can anyone clarify for me the operation of the two speed?

Thanks
The outside gears are your first speed and the inside gears are your second.
If you tighten the shift point screw to much then you wont hit second gear as if you lossen the shift point screw to much you will be by-passing first gear. Possibly why you are chewing the outside gear up is because it is the largest which means when your upper & lower arms flex forward the upper turnbuckel rubs on the teeth. You can reduce this from happening if you put a little toe out on your rear wheels.

Good luck:)
 

Bigger the Better

LSF Plus Member
PLUS member
Messages
7,738
Location
Minnesota
Possibly why you are chewing the outside gear up is because it is the largest which means when your upper & lower arms flex forward the upper turnbuckel rubs on the teeth. You can reduce this from happening if you put a little toe out on your rear wheels.
Or go alloy and use the risers shown here. I cannot be sure they will work with two speed but cant see why not?
http://www.putfile.com/pic.php?img=5113159

Here is the flex. You can see even with the stock set up this is how most gears are taken out.:(
http://media.putfile.com/Rear-arm-flex
 

pep37412000

Well-Known Member
Messages
86
Location
GA.
Hey magnum57 send som pics not sure about the carson though where do you get parts and are they fast I like the fg but if carson is ok maybe i'll give it a try
 
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