Front One-Way Diff for 4WD On-Road Car

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So if I understand correctly I'll have handling issues. Making the rear swing. I actually purchased the 40 tooth on accident when I built a completely separate one way diff to switch back and forth. Didn't install the 40 gear just a stock one
 
myrcbud said:
So if I understand correctly I'll have handling issues. Making the rear swing. I actually purchased the 40 tooth on accident when I built a completely separate one way diff to switch back and forth. Didn't install the 40 gear just a stock one
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this is a hard ? to answer. byron I do not know your skill level. putting the 40 in front will make the front wheels spin. the roll out needs to be the same front & rear. putting it in the rear will make the car basically a 2wd car(rear wheels overdrive front one way). the best advice I can give you is if you have a track with timing system try everything & go with what ever gets you around the track the fastest.
 
myrcbud said:
So if I understand correctly I'll have handling issues. Making the rear swing. I actually purchased the 40 tooth on accident when I built a completely separate one way diff to switch back and forth. Didn't install the 40 gear just a stock one
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See attached and determine if the overdrive will help you. The following is from the Xray NT1 Setup manual.
Screen Shot 2016-04-10 at 5.45.34 PM.webp
 
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I have been doing this since the 70's I have had 1/10 & 1/8 scale BMT & Serpents and I know when my car is pushing thru the turns. My 1/5 scale car is not pushing or drifting thru the turns. The diameter of my frt & rear tires are not the same which may explain why overdrive setup works and yours does not I also use a custom made belt tensioner . And I have a modified motor.
 
Rager, I believe the reason your Overdrive does not work is because you left out one of the most important components of a Overdrive system tire diameter. The tires up front need to be smaller than the tires in the rear . When the tires in the rear get smaller in size the Overdrive effect starts to go away. No difference in size between the front and back equals very weak Overdrive effect.
 
scooter5200 said:
Rager, I believe the reason your Overdrive does not work is because you left out one of the most important components of a Overdrive system tire diameter. The tires up front need to be smaller than the tires in the rear . When the tires in the rear get smaller in size the Overdrive effect starts to go away. No difference in size between the front and back equals very weak Overdrive effect.
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scooter5200 I have no doubt you know what your doing. you are correct the front tires need to be smaller diameter than the rear when over driving the front. you don't seem to understand why this is. this to make the front ratio = the rear ratio so all 4 tires have the same roll out. but anyway my ? for you is what car do you have & what tires are you running front & rear? if I knew this it might help me to understand.
 
scooter5200 said:
Rager, I believe the reason your Overdrive does not work is because you left out one of the most important components of a Overdrive system tire diameter. The tires up front need to be smaller than the tires in the rear . When the tires in the rear get smaller in size the Overdrive effect starts to go away. No difference in size between the front and back equals very weak Overdrive effect.
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So are you using smile tires on a 5th scale scooter? If so, where are you getting them?
 
Before any of you attempt this conversion make sure the club you race at allows you to use tires of different diameter before you spend alll this money on the conversion. Rager the rollout willl be different between the front and the back for a system using a Overdrive not equal. Thats one of the reasons you need a oneway so the front end and the rear end don't end up battling each other.
 
Rager, don't you own a 4wd contrast?? If you do don't waste time trying to figure out Overdrive you should be experimenting with different size pullies to alter the % of Overdrive on that Contrast.
 
myrcbud, I look in the rash containers after we finish racing and collect all the worn tires take them home and true down. Not a easy job . Tires must be even and true or else you can't used them.
 
scooter5200 said:
Rager, don't you own a 4wd contrast?? If you do don't waste time trying to figure out Overdrive you should be experimenting with different size pullies to alter the % of Overdrive on that Contrast.
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I own a Contrast as well. Maybe I should experiment on different size pulleys
 
scooter5200 said:
Before any of you attempt this conversion make sure the club you race at allows you to use tires of different diameter before you spend alll this money on the conversion. Rager the rollout willl be different between the front and the back for a system using a Overdrive not equal. Thats one of the reasons you need a oneway so the front end and the rear end don't end up battling each other.
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but if you overdrive the front they are battling each other under power.
scooter5200 said:
Rager, don't you own a 4wd contrast?? If you do don't waste time trying to figure out Overdrive you should be experimenting with different size pullies to alter the % of Overdrive on that Contrast.
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yes I do. I sold my carbon fg to myrcbud. the contrast is set up on a race platform not a sport platform. that is why they do not replace the front diff with a one way. they put the one way on the jack shaft. the only reason for this is to get brake bias not overdrive. they under stand replacing the diff with a one way would create a push in a 24lbs car doing 60mph. I never said I wanted a one way or overdrive. I said it makes the car easy to drive but is slower.around a groomed track. I can't seem to make you understand that if you remove the gears out of the diff & replace them with one ways under power in a turn one of the wheels is spinning causing it to brake traction allowing a good driver to cut under you coming out of a turn. I see it all the time. this is why in a 30 minute main the 2wd cars average 10 laps more than 4wd. now you say you put worn out tires on front & you get more steering when every one else dose this to reduce steering. lets just agree to disagree & let this drop.
Supa_Mario said:
Hi guys,

I need some advise/feedback on the front one-way diff. Currently I own a FG 4WD on-road car. I have been hearing a lot of positive stuff from the smaller scale racers (1/10, 1/8) about the front one-way differential on a 4WD car. Have anyone with a largescale 4WD car tried the one-way diff on their cars? If so, what are the advantages and disadvantages? I would appreciate if someone can enlighten me on this. Don't quite understand on when will all the 4 wheels be powered, when the front one-way kicks in and what triggers the 4 wheels to power up again. supa mario in my opinion the one way will make the car easy to dive but at a cost(slower lap times). the one ways kick in any time you get into the throttle. as fore 1/10 & 1/8 go that would be like a nascar driver asking a f1 driver for his setup!
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Rager, those worn out tires I true them down before I use them. And I can't make you understand your overdrive set up is wrong if you don't address the tire diameter issue. My car does not push in the turns with my setup. But since you like the gear diffs stick with them . Because what works for me may not work for you or you may not like the way it feels. Have a good season racing. I just recieved a whole bunch of parts from my machinest 4 months late for my FG to up date it more testing I won't be on her for another month.
 
I just finished putting my new diff gear on I had to do some modifications to get the gear to fit on the oneway. The car is alot faster. But my belt tension failed going to have to redesign it. Or get a different size belt.
 
I forgot I had a MCD Rally car with gear diff in the front and the back and it was a pig going thru he turns it did not matter what weight diff oil I put in there it pushed thru the turns. Thats why I got the 4wd and put FG And put the oneway in it and noticed an improvment in handling,
 
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