DIFFERENT differentials - do you beg to differ?

SHY · #1 02-04-2008

Back in the 80s we had the gear diffs. Those were quite smooth I thought back then, and practically maintenance free.

Then the ball diffs came (I now know that Cecil Schumacher invented it, and that their logo illustrates just that, thx)... They cost more than the whole car and were much better it was claimed.

Can someone do a short story about why this is better?

I'm quite sure I read that Serpent is making a gear diff for their S400 (TC), that would be adjustable? Anyone got more on this? Will they try it also in the S500?

Personally I think the ball diffs work fine, but they don't last very long. For 1:12 it sucks big time! One single run and it's not smooth anymore... Not far as troublesome in 1:10 OR, but still I find it too much work (I'm lazy by nature).

1:8 OR cars use gear diffs because of the abuse right?

Give your thoughts and ideas! Can the ball diff be improved? Can gear diffs be just as good? New and even better solutions?

1:8 TR has a solid rear axle and a front one-way... now that's easy for ya!

SMP tried with a one-way in the rear axle many years ago... why? To stop the WHOLE transmission when coasting...

Has this been tried in 1:10 OR?

Chrislong · #2 02-04-2008

Quote:

Originally Posted by SHY

SMP tried with a one-way in the rear axle many years ago... why? To stop the WHOLE transmission when coasting...

Has this been tried in 1:10 OR?

How would 1/10th OR perform with two one ways, and brakes via servo and disk?

Id like to cut out the maintenance of ball diffs, when they are good they feel great but when they go they're a pain at times. Plus the quality of the chinese AE and Losi stuff is far lower than what the Losi and AE stuff were like back in the early days of the B4 and Losi xxx/xx4.

Chris

Lee · #3 02-04-2008

How would you slow the car down with one ways at either end?

SHY · #4 02-04-2008

Quote:

Originally Posted by Lee

How would you slow the car down with one ways at either end?

The Slide had a brake disk directly on the rear axle

They gave it up for 1:8 TR though, too much power so they never got it to be reliable...

@Chris: I'd love to try an RC car with a dedicated servo for the brakes! (not legal) You'd operate this with your foot, so you could brake and give throttle at the same time, to keep the momentum through the corner - just like when racing 1:1 scale

Chrislong · #5 02-04-2008

Quote:

Originally Posted by Lee

How would you slow the car down with one ways at either end?

LOL, Disk brakes via a servo dude

SHY guy, that'd be cool - proper toe and heal racing with a buggy.

josh_smaxx · #6 02-04-2008

Serpent HAVE made a geared diff for the S400, most of the team drivers are using it and think its great. Its adjustable by changing the thickness of oil in it (same as 1/8th OR diffs). Its only 5g heavier than the ball diff (are there light!) and the people using it much prefer it due to the reduced maintence and much more reliable tuning (its the same everytime you use it whereas with building a ball diff every 3 or 4 races its difficult to get it exactly the same every rebuild).

Chrislong · #7 02-04-2008

Quote:

Originally Posted by josh_smaxx

(its the same everytime you use it whereas with building a ball diff every 3 or 4 races its difficult to get it exactly the same every rebuild).

If I have 5 new ball diffs to build, all 5 will be identical once built. its easy.

Your comment is only valid if talking about rebuilding a ball diff with used parts. What tends to happen then is it'll be smooth until the grease is run in, then it'll just be dog rough again.

DCM · #8 02-04-2008

unless you are using a vernier torque meter, it is hard to get a diff exactly the same each time, even using new parts each time, plus the diff has to settle too, which adds to the work, whereas a geared diff, once built, will operate right away, and if rebuilt, with the same oil, will operate exactly the same way.

The only down side of the geared diff, is it removes any 'give' in transmission if you are not running a slipper, hence why the rallyx stuff is well over engineered.

josh_smaxx · #9 02-04-2008

Quote:

Originally Posted by Chrislong

If I have 5 new ball diffs to build, all 5 will be identical once built. its easy.

Your comment is only valid if talking about rebuilding a ball diff with used parts. What tends to happen then is it'll be smooth until the grease is run in, then it'll just be dog rough again.

When i rebuild my serpent diff i cant afford to use brand new balls and plates everytime, its opne so it needs a rebuild every 7 or 8 races. And how long have you been racing Chris? meaning how long have you had practice at rebuilding diffs? it does take some skill to get a ball diff identical every time, i can feel 1/16th of a turn difference in my S400, it takes a few runs to get it back to the same as it was.

Also, the comment was made about Serpent cars and Serpent diffs.

bigred5765 · #10 02-04-2008

also a geared diff ie 1/8th style, can be run much looser than a ball diff with zero slip
and can also be run much stiffer than a ball diff and 100% smoother win win

Lee · #11 02-04-2008

Quote:

Originally Posted by Chrislong

LOL, Disk brakes via a servo dude

SHY guy, that'd be cool - proper toe and heal racing with a buggy.

I understand it would need a disc brake but you would have to have them in the drive shafts if you wanted each wheel to be independent

Also, i have never rebuilt diffs every few races, i raced open diff cars for years and i only ever rebuilt them after a wet race, a lot of it is down to the grease you use

mole2k · #12 02-04-2008

I've often thought with a servo brake it would be quite good to have an xbox style controller with a seperate throttle and brake as triggers then normal steering stick.

Then left-foot braking comes into the equasion!

josh_smaxx · #13 02-04-2008

Quote:

Originally Posted by Lee

Also, i have never rebuilt diffs every few races, i raced open diff cars for years and i only ever rebuilt them after a wet race, a lot of it is down to the grease you use

I used the Serpent stuff that came with it, then i moved onto the schumacher stuff and its ALOT better, would highly recommend it.

I have raced it twice now on one build, its getting raced again then rebuilt, i like to keep on top f the maintenance, would hate to loose and think its because the diff wasnt up to scrath ect.

Lee · #14 02-04-2008

AE green slime

josh_smaxx · #15 02-04-2008

Quote:

Originally Posted by Lee

AE green slime

For diffs?

never knew that.

Lee · #16 02-04-2008

its very good, i also use it on the bevel gears in shaft driven cars

josh_smaxx · #17 02-04-2008

Quote:

Originally Posted by Lee

its very good, i also use it on the bevel gears in shaft driven cars

AWESOME!!

I'll give it a try sometime.

Lee · #18 02-04-2008

Craig drescher told me about it years ago when we first ran the tc3`s

werner1619 · #19 02-04-2008

put my name down for a geared diff,

I always have problems with my 501's diff

mark christopher · #20 02-04-2008

Quote:

Originally Posted by Chrislong

If I have 5 new ball diffs to build, all 5 will be identical once built. its easy.

Your comment is only valid if talking about rebuilding a ball diff with used parts. What tends to happen then is it'll be smooth until the grease is run in, then it'll just be dog rough again.

yup and all five will be different once run so unless you use em for one run and fit another the performance will change on each unit

(oh and im not picking on you

)

Quote:

Originally Posted by bigred5765

also a geared diff ie 1/8th style, can be run much looser than a ball diff with zero slip
and can also be run much stiffer than a ball diff and 100% smoother win win

the best bit off gear diffs, run em in my S400 and all my ic cars bar the 835 which is a mans car with a front one way and solid rear axle. turn,power,go, hang on