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Gear diff: 4 gear vs 2 bevel gear use

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Gear diff: 4 gear vs 2 bevel gear use

Old 11-12-2019, 05:59 AM
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Default Gear diff: 4 gear vs 2 bevel gear use

Hi All,

Can anyone advice on this, preferably from personal experience and testing. Most often we all use the 4 bevel gear gear diff, though on occasion you'll see the option to use only 2 bevel gears.
When would you prefer the one over the other?
Is a light oiled 4-gear similar to the thicker oil filled 2-gear, is it that simple?
Any difference outdoor vs indoor use?
On specific cars? -Mini, TC, FWD, etc...
Stock, spec or mod use, etc....?
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Old 11-12-2019, 06:31 AM
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Originally Posted by PizzaDude View Post
Hi All,

Can anyone advice on this, preferably from personal experience and testing. Most often we all use the 4 bevel gear gear diff, though on occasion you'll see the option to use only 2 bevel gears.
When would you prefer the one over the other?
Is a light oiled 4-gear similar to the thicker oil filled 2-gear, is it that simple?
Any difference outdoor vs indoor use?
On specific cars? -Mini, TC, FWD, etc...
Stock, spec or mod use, etc....?
thats common with some friends of mine in off road , i tried it in on road and honestly didnt noticed a difference between the 2 even experimenting with different diff oils1
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Old 11-12-2019, 06:37 AM
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On the topic of gear differentials. . Given the high grip track surfaces (black carpet) . Why do
all the top level kits come with a spool in the front as opposed to having a diff. I've also seen
mention of running a diff in front with "putty" or 500k-1-mil oil . I prefer a diff up front with 20-k
& 7-k in the back . My thinking on this , last thing I would want is the added friction induced up front by
a locked spool ( different turning radius).
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Old 11-12-2019, 08:00 AM
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Originally Posted by metalcrafter View Post
On the topic of gear differentials. . Given the high grip track surfaces (black carpet) . Why do
all the top level kits come with a spool in the front as opposed to having a diff. I've also seen
mention of running a diff in front with "putty" or 500k-1-mil oil . I prefer a diff up front with 20-k
& 7-k in the back . My thinking on this , last thing I would want is the added friction induced up front by
a locked spool ( different turning radius).

The best way to learn this, is do the work. You'll answer your own questions.
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Old 11-12-2019, 11:42 AM
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Originally Posted by KE4PJO View Post
The best way to learn this, is do the work. You'll answer your own questions.
The next logical question to ask is, why is there a decline in the hobby ?
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Old 11-12-2019, 05:35 PM
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Originally Posted by metalcrafter View Post
The next logical question to ask is, why is there a decline in the hobby ?

video games
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Old 11-12-2019, 05:42 PM
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Old 11-13-2019, 01:49 AM
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Originally Posted by metalcrafter View Post
On the topic of gear differentials. . Given the high grip track surfaces (black carpet) . Why do
all the top level kits come with a spool in the front as opposed to having a diff. I've also seen
mention of running a diff in front with "putty" or 500k-1-mil oil . I prefer a diff up front with 20-k
& 7-k in the back . My thinking on this , last thing I would want is the added friction induced up front by
a locked spool ( different turning radius).
Due to the caster on our cars, as the car rolls it effectively tries to lift the inside front wheel (downstops etc permitting) So it reduces the grip the inside front wheel can give.
diff's with 1-2.5million in will still have a 'diff action' but are obviously a lot tighter, going as soft as 20k up front will reduce your forward bite a lot.
As far as I recall the CRC black has a lot of side bite (hence the side wall glueing etc) but less forward bite.
Try running a spool and drastically reduce the droop and see what it does.
You'll notice that all the top team drivers high grip setups still use a spool, as a front diff can never reproduce that 'rip' out of corners.
Spools also make the cars more stable.
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Old 11-13-2019, 02:49 AM
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Appreciate all your input. Thanks

So getting back on topic, (ignoring the tc front end discussion for now).
using 2 bevel gears vs 4, what are the differences in fi:
tc (rear diff!)
fwd
m-chassis front or rear?!

When do you prefer 2bevel gear diff over 4g?
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Old 11-13-2019, 05:45 AM
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Originally Posted by Skiddins View Post
Due to the caster on our cars, as the car rolls it effectively tries to lift the inside front wheel (downstops etc permitting) So it reduces the grip the inside front wheel can give.
diff's with 1-2.5million in will still have a 'diff action' but are obviously a lot tighter, going as soft as 20k up front will reduce your forward bite a lot.
As far as I recall the CRC black has a lot of side bite (hence the side wall glueing etc) but less forward bite.
Try running a spool and drastically reduce the droop and see what it does.
You'll notice that all the top team drivers high grip setups still use a spool, as a front diff can never reproduce that 'rip' out of corners.
Spools also make the cars more stable.
Thank you for the detailed response , very much appreciated. I'll try your recommendations shortly.
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Old 11-13-2019, 05:50 AM
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Originally Posted by PizzaDude View Post
Appreciate all your input. Thanks

So getting back on topic, (ignoring the tc front end discussion for now).
using 2 bevel gears vs 4, what are the differences in fi:
tc (rear diff!)
fwd
m-chassis front or rear?!

When do you prefer 2bevel gear diff over 4g?
I would be concerned with accelerated gear wear. Reducing the qty from 4 to 2 gears
may result in failure on a bumpy track .
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Old 11-14-2019, 02:30 AM
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Originally Posted by PizzaDude View Post
Appreciate all your input. Thanks

So getting back on topic, (ignoring the tc front end discussion for now).
using 2 bevel gears vs 4, what are the differences in fi:
tc (rear diff!)
fwd
m-chassis front or rear?!

When do you prefer 2bevel gear diff over 4g?
You'll feel a less "tight" diff, it will have less "kick" at the moment of applying throttle, and it will spin the inner wheel much easier when exiting the corners. It's a very different feel than a lighter oil. I don't think it could be faster unless very low grip conditions
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Old 11-14-2019, 03:04 AM
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With regards to FWD cars, thicker oil is better for front traction. I have also done this to a 4WD car. Thicker oil in front gear diff and lighter at the rear. It performs well in cornering. No under-steering and traction is much, much better. I'm currently using 15k oil.

I have also done something similar to my CC-01 which I use for crawling and trailing. I applied a lot of AWG grease in the front diff and ceramic grease for the rear. The CC-01 performs the way I want it to be.
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