Why no r&P gearing options from vendors?

[miller]

I just saw a post from a new person to this forum and I have always wondered the same thing but never asked. With all the aftermarket things being built I don't understand why something so important is missing from the vendors. I'd love to be enlightened.

Why are there no lower ring and pinion gear sets available? One of the biggest issues with shafties is torque twist. This seems to be the missing piece to minimize torque twist combined with better link geometry. Look at the new losi crawler, lots of gearing with worm gear to reduce/eliminate twist...no reason why there can't be lots of gearing with a r&p. I'm from 1:1 crawling. We can change motors to have more torque hp and higher rpms, change transfercase gearing, and then gearing in the axles. With rc crawlers you can do the first two but not the last. Imagine 1:1's only being able to run one axle ratio....we're missing a huge piece of the puzzle. And stuck on a brutal ratio too. Ax-10 ratio 2.92 Where are my new 5.29's for my new 5.5" HB Rovers?

There's always talk about what gearing the tranny has but nobody talks about what the gearing is in the diffs which is just as important if not more.

The only explanation I can come up with is that if you don't come from 1:1 and have been involved with other rc's all the gearing comes from the tranny which gets sent directly to the tires in most other cases so there isn't any thought given to axle gearing

[yoda316]

i agree with this idea .
it would be awesome to have different ring and pinion ratios available.
i know that there is a low gear set available for txt axles .
i dont know how they could make a lower gear set for axial axles without changing the axle case(cheap plastic anyways so thats not a huge problem)
i think i would be worried about the strength of lower gears though.

[miller]

Just because I can't sleep I did some reading using stock Ax-10 data and have a better set up that I'd like to try.

Stock Ax-10
Internal tranny gears 2.6
Stock pinion (14 tooth) and spur (87 tooth) 6.21
Total tranny ratio = 16.15

^^^^^ That is the problem, very low sprung weight, so very soft springs on shocks (which are always on a slant decreasing effectiveness) with lots of torque on the chassis = torque twist. And then multiply that by bad link geometry. That's how I see it and I could be very wrong.

All that leverage sitting on the chassis then gets pushed to a 2.92 ratio ring and pinion in the diffs for a final stock crawl ratio of 47.2 which I like with my 7t on 3cell.

I'd like to try this:
Internal tranny gears 2.6
20 tooth pinion 87 spur 4.37 (it'd be nice if they made smaller spur gears too not sure if they do)
Total tranny ratio = 11.36

^^^^^ More torque taken off the chassis and moved into the axles.

And have that move down to 4.15 ring and pinion to keep the same final crawl ratio at 47.2....just a transfer of where that torque is happening. It'd be great if a vendor made a bunch of 1:1 common ratios like 4.56, 5.29 etc.

This would result in less strain on the tranny outputs, less strain on driveshafts, less strain on r&p, more strain on axle shafts and lockers. And in theory reduce torque twist. It would also increase the strength of your drag brake...I think, thoughts?

I'd also be interested in how this would effect run time and the type of motors you could run. Because the final drive ratio is the same do run times stay equal? Or would run times change with the change of where the gearing is happening. Because more gearing is happening at the axle does the motor need less torque?

Now I'm tired :-(

[jedrattle]

Probably because of the lack of a way to adjust the gear mesh.

[sloppy]

Originally Posted by jedrattle

Probably because of the lack of a way to adjust the gear mesh.

gear mesh could be adjusted.. I think it is just overly involved for most people and if a vendor made something there would be nothing but problems because the end user wouldnt be able to figure out how to use it..

and unlike 1:1 where gearing in a tranny would be harder to change here it is the easiest thing to change and the diffs are allot more involved, this doesnt mean its the best solution but it is the easy one..

[miller]

Pulling apart a tranny to install new outputs for dig would be no harder. Throwing in a new ring and pinion with a different ratio would be just as easy as putting in a new stainless locker. I don't see how that is overly involved.

To make it easier a full new ring and pinion ratio with a spool would make it even more simple.

As for gear mesh...that's a non issue I think unless I'm missing something. I could be missing something but isn't it just as simple as making a different ratio that will fit in the same housing? Should be the same as 1:1 on that end.

[RocSpyder]

The reason that there are no different ratios for the Ring and pinion is cost. It would cost way more to change the ratio by way of the ring and pinion. A new pinion for the motor is only a few bucks, and you dont have to take the axles apart to change your ratio.

Changing the ring and pinion ratio would have more benifits as you stated above, but its just not nearly as pratical cost wise.

[miller]

That's a bad excuse. There's no higher cost for stamping a new ring and pinion with a different ratio and no more inconvenience to putting in the gears.

How many people have avoided buying heavy duty ring and pinions, straight axles, or lockers because it was too inconvenient to pull the axles. This is an rc that you can pull apart in 5 minutes on your coffee table. And gearing isn't something you change on a regular basis.

[RocSpyder]

Originally Posted by miller

That's a bad excuse. There's no higher cost for stamping a new ring and pinion with a different ratio and no more inconvenience to putting in the gears.

How many people have avoided buying heavy duty ring and pinions, straight axles, or lockers because it was too inconvenient to pull the axles. This is an rc that you can pull apart in 5 minutes on your coffee table. And gearing isn't something you change on a regular basis.

I was stating from a consumer perspective. Not many people are going to shell out $30+ for a ring and pinion when a single $3 motor pinion basically does the same thing.

[cartronicshn]

Very interesting thread, i have also wondered why there weren't any different r&p ratios out there, let's hope a vendor gets involved on this topic

[mockknight]

May the reason being that the teeth on the R&P will be too small?

Just like in Toyota 1:1 world. No one goes below 5.29 due to the fewer number of teeth need on the pinion to acheive that ratio. You lose pinion to ring gear contact, there for making the pinon the weak link.

Just a thought

[miller]

Originally Posted by RocSpyder

I was stating from a consumer perspective. Not many people are going to shell out $30+ for a ring and pinion when a single $3 motor pinion basically does the same thing.

I know...and what I'm saying is that it wouldn't be a consumer problem. How many heavy duty ring and pinions have been bought for the ax-10...probably a few. And if you sold something for $30 an axle that reduced or eliminated torque twist, the biggest issue with a shafty, they'd be flying off the shelves.

And if you had $60 worth of gearing in your ring and pinions (front and rear $30x2) plus a $3 pinion you could potentially be saving money because your stock driveshafts would hold up and your stock output's would hold up. So right there you wouldn't need over $100 in parts that you would have otherwise spent upgrading. That's looking at ax-10 axles.

Originally Posted by cartronicshn

Very interesting thread, i have also wondered why there weren't any different r&p ratios out there, let's hope a vendor gets involved on this topic

That's what I was hoping...I thought maybe there was some issue I had overlooked that makes it impossible but so far nothing holds water.

I was also hoping Holmes might be able to chip in some ideas about run time and motors.

Originally Posted by mockknight

May the reason being that the teeth on the R&P will be too small?

Just like in Toyota 1:1 world. No one goes below 5.29 due to the fewer number of teeth need on the pinion to acheive that ratio. You lose pinion to ring gear contact, there for making the pinon the weak link.

Just a thought

I though about this too but the materials that can be used on small scale are far stronger than what you can use in a 1:1 if you had to make them stronger. You aren't dealing with the same heat or wear issues so you can use stronger materials.

I think the real reason is that solid axles are relatively new as is crawling and it's an oversight in the market that comes from tranny gearing being the be all end all in other forms of RC's. (That's speculation because I don't know anything about rc's outside of crawling.)

[Duuuuuuuude]

A higher r/p ratio would be ideal. Like you said, so much stress would be relieved from the trans and driveshafts. I would imagine run times would increase somewhat because the trans/motor wouldn't have to work so hard, and torque twist would be greatly reduced.

In the long run it would be cheaper. Think about how much money is spent on metal trans gears (so the won't strip), cases (so the new metal gears won't blow it up), and reduction units. Hell, just look at the aftermarket trans selection vs diff selection. Its night and day. Even when you do find a fully aftermarket diff it might have upgraded gears, but its still the stock ratio.

I really don't think its a matter of build cost. How much does it cost Axial to pump out a fully built axle? $10 per? How much would it cost them to whip out one with different gearing? $10 per? Maybe $11 or $12?

If I could get a better ratio for my Maxx diffs, it would be well worth the $60. I'd buy them the first chance I had...

I know someone. I think a phone call is in order here...

[Harley]

Originally Posted by miller

That's a bad excuse. There's no higher cost for stamping a new ring and pinion with a different ratio and no more inconvenience to putting in the gears.

Having gears made is extremely expensive, that is your single most determining factor. Also with the size of gears we use the difference in ration would mostly have to be made up in the diameter of the ring gear. I have modeled almost every axle typically used in crawling, there is not much excess room in there for large ring gears.

There is an easy solution though...........MOA. HAHAH JK. Just saying that a new R&P ratio is not a project that I expect to work on any time in the near future.

[EeePee]

http://www.rccrawler.com/forum/showthread.php?t=126076

[Reflection]

If someone has the right tooling,it would be rather simple to make different ratios. In my super,I can choose between a 3.3 ratio or a 4.3 ratio.:-P

Originally Posted by miller

Stock Ax-10
Internal tranny gears 2.6
Stock pinion (14 tooth) and spur (87 tooth) 6.21
Total tranny ratio = 16.15



All that leverage sitting on the chassis then gets pushed to a 2.92 ratio ring and pinion in the diffs for a final stock crawl ratio of 47.2 which I like with my 7t on 3cell.

I'd like to try this:
Internal tranny gears 2.6
20 tooth pinion 87 spur 4.37 (it'd be nice if they made smaller spur gears too not sure if they do)
Total tranny ratio = 11.36

You've put up allot of good info. I like the idea personally. Not sure if I would try a set if they were made though. I run Axial trannies in everything. Not really sure if I'd want lower gears in the axles though. Higher would be better for me.

Right now,my Axial based 2.2 truck runs a 19t pinion/87t spur with a 10t puller on 3 cells. It's pretty quick with plenty of bottom end grunt. Wouldn't mind getting a touch higher gear though.

My super runs 18/81 pinion and spur with a 3.3 ratio in the axles. Same motor and voltage. Again,wouldn't mind a touch taller gear for the axle.

Originally Posted by jedrattle

Probably because of the lack of a way to adjust the gear mesh.

Shim kits are easily found at most hobby shops or online stores. Shims will only get you so far though.

Originally Posted by miller

As for gear mesh...that's a non issue I think unless I'm missing something. I could be missing something but isn't it just as simple as making a different ratio that will fit in the same housing? Should be the same as 1:1 on that end.

2 ways of doing it. As I'm sure you are aware,the pinion in any axle with a lower gear set will be smaller than a higher gear set. You can shim to a certain extent. After that,a diff or spool would be needed with an offset to push the ring gear into the pinion better,for proper gear mesh.....or,put the needed offset on each gear set so they fit the stock housing and can be shimmed up right.

It's all very feasible to do.

[EeePee]

http://www.photobox.co.uk/album/24252964

[miller]

Originally Posted by Harley0706

Having gears made is extremely expensive, that is your single most determining factor. Also with the size of gears we use the difference in ration would mostly have to be made up in the diameter of the ring gear. I have modeled almost every axle typically used in crawling, there is not much excess room in there for large ring gears.

There is an easy solution though...........MOA. HAHAH JK. Just saying that a new R&P ratio is not a project that I expect to work on any time in the near future.

MOA's are for cheaters :-P With a r&p set the diameters would stay the same as long as they are both designed to work together not just a larger ring gear or just a smaller pinion.

And they can't be that expensive to make otherwise the market wouldn't be filled with HD ring and pinions for relatively cheap prices. What's the difference of offering a heavy duty gear set in a different ratio. You're still incurring the cost of making gears either way aren't you?

I think you need a challenging project harley Get on a new gear set for the ax-10.

34 tooth ring gear and 8 tooth pinion boot up the solid works

[miller]

Originally Posted by raptorman57

or,put the needed offset on each gear set so they fit the stock housing and can be shimmed up right.

It's all very feasible to do.

This is what make the most sense. A ring and pinion set with a spool built in as one piece. Simple pop it in and go. Takes up the same space and takes the thinking out of having to shim them up, or grind the housing to make room for bigger stuff.

The main advantage that I see coming from this is minimizing torque twist or eliminating it. You can still do all the gearing changes you like through pinions and spur gears.

You guys are the big dogs...where's that bender dood. Get him to have axial punch them out.

Originally Posted by raptorman57

Not sure if I would try a set if they were made though. I run Axial trannies in everything. Not really sure if I'd want lower gears in the axles though. Higher would be better for me.

The idea is you'd run a larger pinion off the motor to increase you gearing at the tranny. You're final crawl ratio would be exactly the same as it would have been before the gear change...but the torque on the chassis would be minimized. You'd have the same wheelspeed....everything just less or no torque twist. It's broken down in post #3. I guess in your boat you'd have to get on the horn for them to make smaller spur gears so the axle gearing wouldn't eat up your need for speed while still transferring the torque to the axles. There'd be huge benefits in this for rock racing too.

Originally Posted by EeePee

http://www.rccrawler.com/forum/showthread.php?t=126076

Very cool...not a single reply to it because everyone was probably scratching their heads wondering why you'd bother doing that instead of buying a $3 pinion lol. He should have titled it lower axle gearing mod to eliminate torque twist and I bet the thread would have been on fire.

[dirk379]

Two words:
enroute berg