The New SSD-RC High Ratio Wraith Transmission Kit

[KRAWLR4life]

Hey guys, thought Id share this lil' GEM with you!
I just got the SSD-RC High Ratio Trans kit (Part No. SSD00016) and
I cannot believe the quality of this transmission for the price you
payfor it!
I got this trans for my U4RC 2.2 Trophy class rig, I like the ideal
of getting a little more wheels speed without adding more motor or
over gearing.
This High Ratio Trans comes almost complete, so its considered a 'kit'.
You can either strip your old Wraith tranny for the parts
needed to complete it or just buy a few new parts for it and save
your old trans, that's up to you!
I went ahead and built this trans with new parts, I'll add the needed
part numbers below for anyone who wants to built it new!
It is recommended by SSD-RC to run the under drive gears (43/13T)
in the front and rear of your axles to obtain optimal gearing and very low torque twist.
The stock Axial trans ratio is 2.6:1, this SSD-RC trans ratio is 1.8:1,
it should help out the top end speed!
Another AWESOME feature to this trans in the 3MM think motor plate!
Its think! Your not stripping anything on this motor plate!

Once I get this trans installed into my U4 rig, Ill test it out and let
you all know how well it holds up, I will be testing it in the most
harshest of RC environments.. U4RC Racing!

All greased up and ready to build!








Its a work of art!


Parts needed to build a complete trans from this kit:
Stock Axial transmission input shaft (AX30198 or AX31149)
Stock 20T drive gear (AX30162)
Stock Axial transmisison idler shaft (AX31090)
Stock Axial transmission gear cover (AX8007
Stock Axial slipper clutch assembly
Bearings needed:
(4) 5 x 10 x 4mm
(1) 5 x 11 x 4mm
(1) 8 x 16 x 5mm
(1) 15 x 21 x 4mm

Thanks SSD-RC for yet another great product!!!
Click here for more info! HRT KIT

[maslin]

"Normal" gearing with this trans vs "high" gearing on a normal trans is the exact same strain on a motor, correct?

Seems like it just makes it easier to over gear, unless your motor is up for it.

[Del Monte]

What Spur/pinion combo are you running with that?

[KRAWLR4life]

Originally Posted by Del Monte

What Spur/pinion combo are you running with that?

Im not sure yet Jake, I was probably gonna start with 56/13 and go from there.
I'm having a hard time trying to figure out the proper gearing in my head, so I'm totally open to suggestions for those that know all about 'optimal gearing'

[fr8cture]

Yikes I run 12/56 on a stock trans. lol

[Harley]

I did a video on this trans awhile back.

[maslin]

Originally Posted by KRAWLR4life

Im not sure yet Jake, I was probably gonna start with 56/13 and go from there.
I'm having a hard time trying to figure out the proper gearing in my head, so I'm totally open to suggestions for those that know all about 'optimal gearing'

Are you trying to go faster? 2.6 to 1.8 is nearly 150%. If a 3300kv motor at 4:1 goes roughly 20, it will now go roughly 29.

If you just wanted a nice solid shiny case but the same speed, you need to drop your gearing 30% ish.

[KRAWLR4life]

Thanks Harley for the link to your video, somehow I missed it but glad I got to see it now, it was really informative!

Originally Posted by maslin

Are you trying to go faster? 2.6 to 1.8 is nearly 150%. If a 3300kv motor at 4:1 goes roughly 20, it will now go roughly 29.

If you just wanted a nice solid shiny case but the same speed, you need to drop your gearing 30% ish.

This equation makes more sense on where I need to start from, thanks for the info Maslin!

[Eric0424]

Originally Posted by KRAWLR4life

Im not sure yet Jake, I was probably gonna start with 56/13 and go from there.
I'm having a hard time trying to figure out the proper gearing in my head, so I'm totally open to suggestions for those that know all about 'optimal gearing'

Final Drive Ratio on the stock transmission and stock axle gears using 13/56 pinion & spur would be 32.74:1. With SSD transmission it jumps to 22.66:1. If you run the under drive gears it would be 25.65:1 with the SSD trans.

Personally I would be targeting 11/58 (27.74 FDR) or 11/56 (26.68 FDR) as starting point with the SSD transmission and stock axle gears if I were looking for more speed. Or 10/58 (30.52:1) if I were looking for something closer to stock.

If you're running the under drive gears in the axles you could probably bump up a tooth on the pinion with the above pinion & spur suggestions.

For reference:

Spawn, stock trans, 32 pitch pinion/spur & stock ratio axle gears, FRD is 35.47:1

[KRAWLR4life]

Originally Posted by Eric0424

Final Drive Ratio on the stock transmission and stock axle gears using 13/56 pinion & spur would be 32.74:1. With SSD transmission it jumps to 22.66:1. If you run the under drive gears it would be 25.65:1 with the SSD trans.

Personally I would be targeting 11/58 (27.74 FDR) or 11/56 (26.68 FDR) as starting point with the SSD transmission and stock axle gears if I were looking for more speed. Or 10/58 (30.52:1) if I were looking for something closer to stock.

If you're running the under drive gears in the axles you could probably bump up a tooth on the pinion with the above pinion & spur suggestions.

For reference:

Spawn, stock trans, 32 pitch pinion/spur & stock ratio axle gears, FRD is 35.47:1

Thanks Eric0424, this really helps! So whats the 'formula' to compile spur/pinion, trans and
axle gears final ratio? This way I can understand better on how you came up with those FDR's?
I was always bad at math but I'm sure I can learn this very important part of gearing for racing.

[maslin]

Everything is reduction.

motor KV x volts = rpm
divided by pinion/spur ratio
divided by trans ratio
divided by axle gear ratio

times circumference of tires. Plus balooning. It isn't going to an exact figure.

But the final drive is just the middle part. Spur/pinion x trans x axle ratio.


I think? ha

[Eric0424]

The formula for determining FDR is simply multiplying the spur/pinion ratio times the transmission ratio and then times the axle gear ratio (spur/pinion x trans x axle ring/pinion = FDR). Figuring each of these ratios is just dividing the number of teeth on the driven gear (spur, transmission diff and axle ring gears) by the number of teeth on the drive gear (pinion, transmission topshaft and axle pinion gears).

For example:
Pinion / Spur
56 / 13 = 4.308

Bottom gear / Top gear in trans.
52 / 20 = 2.60:1

Axle Ring gear / Pinion gear
38 / 13 = 2.923

Take those results and multiply them together.
4.308 x 2.60 x 2.923 = 32.74:1 FDR

I believe the bottom gear in the SSD transmission is a 36 tooth gear and the stock top gear is 20 tooth, giving us a 1.8:1 ratio. The 43/13 ring & pinion gear set is 3.308:1.

Using the 56/13 spur & pinion, the SSD transmission and the 43/13 under drive axle gears.
4.308 x 1.80 x 3.308 = 25.65:1 FDR

These numbers may vary a little depending on if and/or where you decide to round up on the right side of the decimal point. Idler gears do not factor into the ratios of the transmission, they simply transfer motion from the drive gear to the driven gear.

[SCREAMER]

Lots of great info in this one! Great video Harley, as always. I might pick one of these up for my second Wraith.

[KRAWLR4life]

Originally Posted by Eric0424

The formula for determining FDR is simply multiplying the spur/pinion ratio times the transmission ratio and then times the axle gear ratio (spur/pinion x trans x axle ring/pinion = FDR). Figuring each of these ratios is just dividing the number of teeth on the driven gear (spur, transmission diff and axle ring gears) by the number of teeth on the drive gear (pinion, transmission topshaft and axle pinion gears).

For example:
Pinion / Spur
56 / 13 = 4.308

Bottom gear / Top gear in trans.
52 / 20 = 2.60:1

Axle Ring gear / Pinion gear
38 / 13 = 2.923

Take those results and multiply them together.
4.308 x 2.60 x 2.923 = 32.74:1 FDR

I believe the bottom gear in the SSD transmission is a 36 tooth gear and the stock top gear is 20 tooth, giving us a 1.8:1 ratio. The 43/13 ring & pinion gear set is 3.308:1.

Using the 56/13 spur & pinion, the SSD transmission and the 43/13 under drive axle gears.
4.308 x 1.80 x 3.308 = 25.65:1 FDR

These numbers may vary a little depending on if and/or where you decide to round up on the right side of the decimal point. Idler gears do not factor into the ratios of the transmission, they simply transfer motion from the drive gear to the driven gear.

Thats great! That puts things into perspective and much easier to understand!
Thanks for everyones input, I thought I knew a lot but and I guess
you can never know too much!

[Rybroca]

Any life left in this thread? I'm thinking about this 2 speed for my Spawn. I keep thinking a 35t motor would be perfect. With the Spawn sitting stock there's no more throttle to visit when I want speed and it gets too hot for my liking. It seems like it would be great to shift to high gear and rarely hit full throttle! Brushless looks great, but I like the tangibility, waterproof-icity, the feel and function of brushed... and of course the tinker factor of the 2-speed!

[altd896]

This wasn't about a 2 speed, was a higher ratio than stock.
2 speed is unlikely to give the result your looking for, most 2 speed have a high gear similar to the stock Wraith trans with a lower 1 st gear, will slow rig down but not sure it up.
Secondly if your 35t already gets hot, gearing it higher to go faster is only going to make it hotter, regardless of it your at 50% or 100% throttle.

[Rybroca]

Yeah. Wrong thread. But it is the same ratio as the two speed's high gear. Sorry, I'm running a 20t motor with stock gearing. Do you think a 35t motor on this high ratio Wraith transmission would be faster at top speed than a 20t Wraith spawn running stock gearing?

[WHITE-TRASH]

Originally Posted by Rybroca

Yeah. Wrong thread. But it is the same ratio as the two speed's high gear. Sorry, I'm running a 20t motor with stock gearing. Do you think a 35t motor on this high ratio Wraith transmission would be faster at top speed than a 20t Wraith spawn running stock gearing?

If all you're worried about is higher gearing just change the pinion and spur.

[altd896]

Originally Posted by Rybroca

Do you think a 35t motor on this high ratio Wraith transmission would be faster at top speed than a 20t Wraith spawn running stock gearing?

Nope, 3mph slower
I like this little calculator to work out this stuff
R/C Calculations