Hey, What do you guys think of diff oil. My dad thinks it is rubbish but we bought it any way and am going to put in my Lightning 2.

well if you want to balance your car up you want @700-2000 in the rear, @10000 in the centre and @3000-7000wt in the front...

Thanks for the reply I've put 1000 in the rear, 10000 in the centre and 5000 in the front. Also when there was grease in the diff it was real easy to turn but when i put the oil in the centre diff it was far harder to turn. Why is this. Also i heard that you only fill it 2/3 thirds of the way up is this true. My dads taking a pyhsco because he thinks it is rubbish. Will it change when i get to the track.

Could you tell me how to check if someone replys to you without going through all the forums i've posted.

2/3rds full is correct, on the track you will find that it will get the power down better and less wheelspin, the reason its now stiff to turn is that the oil essentially adds a mild LSD effect, this means that if the front or rear loses grip it wont just spin those wheels up and lose you drive...

On a flat grippy surface diff oil isnt so important, but with bumps etc the diff oil is essential...

you wont immediately notice a big difference but the more you drive it the more you'll see and feel how it behaves differently, you could always tell your dad "if thats the case why not some crisco?" [>:]

Thanks for reply the buggie seems to be going really real. We have noticed that the buggie with the Picco P7-R seems to be eating the gears while my dads 21 nitro star BB has had its gears in it from march and is still going well so im gonna buy hardened steel gears. We are also experitmenting with clutch bells in the Picco. I tried a 13 tooth but it was too wicked, tried a 14 tooth was better but was still a bit wicked so im gonna buy a 15 tooth.

I too have the lightning2, which is now 90% pro spec. You will definatley need the hardened steel diffs if you are using the P7-R. i read somewhere that graham89 even uses a 17t clutchbell to tame the beast.

I don't know if you could race in most american tracks with a 17tooth bell and still be competitive.

grahma is in england and his track allows him to be in the powerband all the time although it does mean he takes the corners very wide but again his track allows it and he doesn't loose speed because of it.

Mark?

Whats happening r u losing control of the rear end or is the steering not as quick/snappy?
tell me more

Stuart.

Stuart

If you are lighting up the inside front when exiting a corner then go thicker on the front diff... if its power understeering badly (both front wheels sliding out) then go thinner...

If you are losing drive due to rearward weight transfer (lighting up both fronts on the straight) then go thicker on the centre diff...

Thats the limit of my knowledge, the rest I just copy in the vane hope it will somehow improve my driving ability, but alas it never does

Yea- I know where Grahama's from thanks. Did ya'll hear- He just went over to the darkside and got himself a K-Car. Between that and the XB8- I Haven't heard him make mention of his Hypers Lately. LOL!! He got a 777 Sp1.

I have the sports RTR and i just upgraded my diffs with the two extra bevel gears in each, and also did 5k 7k 3k front center rear... it made a HUGE difference over stock. I noticed it right away

Simple rule of thumb I have been thinking about seems to be go thinner the more grip you have and go thicker to impact the wheels that are spinning...

If you focus on the front and centre diffs as they are the ones likely to unload the most losing you drive, going too thick on the rear diff will stop it unloading but at the expense of traction...

ie if the inside rear wheel spins up, you lose drive thru a corner slightly, if you go thick on the rear diff then the "axle" becomes more like a Kart, and when both wheels are driving then you can break the traction and cause violent oversteer...

Its worth remembering that grease acts differently to oil, as the oil has some "flow" or viscosity ensuring it is always making contact with the bevel gears, grease will tend to be flung off the bevel gears and only centrifugal/centripetal forces acting on it due to the diff spinning will put it back in contact with the gears, in essence it acts like a thin oil offering very little resistance and therefore not "tightening" the diff up..

Torsen diffs work differently in that they sense which wheel is turning more slowly and apply more toque to that wheel as long as both sides of the diff have some grip, if one side unloads then the diff will spin up like a normal diff...

LSD's or limited slip differentials are the ultimate diffs as they will not unload like a torsen or a bevel gear diff... they allow the inside wheel to turn faster for grip while cornering, but if the inside wheel slips, then they wont over drive it and transfer power away from the outside wheel... if the inside wheel loses grip then they lock up maintaining drive to the outside wheel...

The downside of LSD's is that with a lot of power applied they can cause the outside wheel to lose traction as well and this will cause sudden oversteer (rear diff) or understeer (front diff)

Adding thicker oil to a diff is an attempt to make it act more like a LSD, but it will not compensate for ham fisted throttle useage

Typical uses of LSD's in full scale are on the front wheels of FWD cars to stop you lighting up the inside front wheel in hard cornering, sort of mechanical traction control... they are also used in 4WD's to ensure that you get maximum torque to all 4 wheels in very slippery conditions...

sorry galifrey i made a typo error on the first post i meant to ask young lightning what was happening

NP stuart

I thought you were a different stuart...

But having seen your question it made me think about a short guide to diffs, which can help everyone

heres some similar info from neo buggy

Differential Settings
---------------------
Differential's are used to allow the wheels on the same end of the car to rotate at different speeds during cornering.
If diff's are set to tight or are "locked" the tires will fight each other as the car is turning.

Front Diff Looser than Rear Diff
Steering response increases
If rear diff is to tight, the car will understeer into the corner, and will cause loss rear end sliding out of the corner.
Could cause oversteer while entering the corner (depending on other settings)

Rear Diff Looser than Front Diff
Steering response decreases, stability in turns in increased
Could cause understeer or "push" while entering the corner (depending on other settings)

__________________________


Assuming we are talking about standard gear diffs. Not Torsen or Spider diffs. When the diff has very light oil in it, the outdrive cups will spin very easily in opposite directions.(diff action) So when the oil is very thick the outdrive cups will spin with a lot of resistance. This is important when one side of the diff becomes unloaded. ie, when one wheel looses traction.

This is most important in, but not restricted to, cornering. When turning the outside wheels have to spin faster since they have to travel farther than the inside wheels. The rear wheels are fixed pretty much staight so easier diff action is more important than in the front. The front wheels turn with the angle of the turning radius and the inside wheel usually turns sharper than the outside so on the front you need less diff action.
In the rear the lighter the oil the less power there is to one wheel if the other lifts or looses traction. The heavier the oil the more power to one wheel if the other wheel looses traction. Most important when turning because usually the inside rear wheel tends to unload. If you have too much drive power to the outside rear wheel when that happens then the rear end breaks loose.
In the front you want both front wheels to pull the buggy around the corner. When cornering chassis weight tends to transfer to the outside front wheel. So you want it to pull hard even if the inside front wheel unloads. So in the front the heavier the oil the more the outside front wheel will pull even if the inside front wheel unloads. This makes the buggy turn quicker under power up to a point. Too heavy wt oil can cause the buggy to push if there is not enough traction to the ground.

As for the center diff. It's still pretty much the same idea. The lighter the oil the less power to either end of the buggy. The heavier the oil the more power to both ends of the buggy. This is mostly important for keeping the buggy stable. If the center diff has light oil in it and one wheel at one end of the buggy looses traction then power to the other end drops off too. This momentarily slows the buggy down and lets the loose wheel regain traction. Heavy oil keeps the power to the opposite end of the loose wheel.

So, most of the time the rear wheels will loose traction more often than the fronts. You want the rear diff very light so when one wheel breaks free the other wheel stops pulling so the buggy does not swing around. It lets the loose wheel regain traction. In the front you want the wheel that still has traction to keep pulling when the other front wheel looses traction. All of this, most of the time, works out to a basic starting point of 3000/5000/1000 wt oil F/C/R.

If there is a lot of traction and you can put a lot of power to the ground then you want to stiffen up the diffs more, like 5000/5000/1000 or even 5000/7000/1000. If the surface is really loose and there is very little traction the you want to soften up the diffs. More like 3000/3000/1000 or so. This all works out to keeping the front end in front and the rear end in the rear. This is a generic setup for standard diffs. Torsens and Spiders work a bit differently. Thats a different story.

Stuart

I am slightly lost now, I thought the more traction you had the lighter you could run the diffs, but that article seems to suggest otherwise...

I guess it depends on whether you are having problems with drive or steering...

My thoughts were....

If you have lots of straightline drive and the front is lifting a lot then i would think you want thicker centre diff oil to stop the front lighting up and the "ming ming ming" effect of the engine peaking as the front loses drive and getting all the power....

However, then if you have lots of traction in the corners I suppose it depends on whether the inside wheel is lifting and losing you drive... if it is go thicker, if it isnt then go thinner on the front to get the maximum benefit of the diff effect....

Would like some clarification/others thoughts as I really want to get to grips with this theory...

I am running 7000/10000/2000 in my TTR-S3 as recommended by Jon Hazelwood (british champion and TT factory driver) and it seems great so far, that was his setup for Slough which is a very bumpy medium traction track...

Sturat, whats happening, is the eamcc (east antrim model car club) they sent me an email. They are thinking of starting 1/8scale buggie racing have you heard anything. Thanks for the help on buggies diff oil. It is easier handled. But dad thinks we should get a 16 tooth clutch bell just to try it.

Thanks to the rest of ya's as well. I've tamed the beast it is easier handled now.[sm=RAINFRO.gif]

do you guys think 7000 front 10000 middle 5000 rear would be too thick for general bashing around??i just got the car used & dont have a clue what is in the diffs if anything other that the stock grease.I dont race but i enjoy using it at dirt lots,job sites ,parking lots,baseball fields Etc.thanks for the help

I run 5 7 3 in mine... and it works great for bashing... almost too well on slippery surfaces.. I am new to the hobby as well, I would test it out first. If you listen to the guys here, they will point you in the right direction, but IMO you need to fill it up with something and test that out, so you get a feel and know what to look for.

If the track you were running on was a football pitch and there is lots of grip. What would be the best thing to do with the diffs. I have a Hong Nor X1-CR with an O.S. V-spec. At the minute i run 10000 in front, 30000 in centre and 5000 in rear.

Don't worry about oversteer or understeer you need to experiment and try different setups yourself untill you find what you like. Here is a similar post I made quite a while ago when my name was little stampy. I made a few changes to it but its the basic rule of thumb showing how a buggy will handle to different diff settings.


ORIGINAL: Little Stampy

Front- thicker gives you less steering responce off throttle and better on throttle "posi" traction pull out of corners because of the even power to both wheels but it could give you slow steering responce off throttle. Lighter oil gives lots of off throttle steering responce because of the low resistance between how fast each wheel spins but less front wheel bite out of the corners because the power gets thrown to the wheel with the least traction instead of having both tires bite into the dirt.

Center- thicker gives more 4wd which can give you some under steer because the rear is pushing the front tires a long to much but great drive with all 4 wheels accelerating the buggy hard and thinner oil will give you a lot of power to the front wheels so it pulls the buggy around on the throttle more giving you good on throttle steering but lacks a little acceleration because mainly the front tires are pulling instead of all 4 digging.

Rear- thicker will give you understeer off the throttle because of the resistance between each wheel spining to the other but as long as your on the throttle and have the tires broken loose of traction it will of corse bring the rear of the buggy around but you can't always break the tires loose like that which can make handling inconsistant... thinner oil will give you quick steering because of the low resistance that will let each wheel spin however fast they need to and it will give you a hard time to break both tires loose under power because all of the power goes to the tire with the least traction which is the inside tire. All in all the rear is only a rudder... if the rear diff weight is to light then the rear of the buggy feels like its swinging in the wind. If its to heavy the rear feels like a big ancor.