Parts/Drivetrain/Pinion gears/Robinson Racing Extra Hard Steel .8 Mod Pinion Gear w/5mm Bore (17T)
Robinson Racing Extra Hard Steel .8 Mod Pinion Gear w/5mm Bore (17T)
Robinson Racing

Robinson Racing Extra Hard Steel .8 Mod Pinion Gear w/5mm Bore (17T)

Part # RRP87173.6(5)
Where to buy
$10.99
AMain Hobbies
Seen Oct 12, 2026
$10.99Buy
Prices are as last seen at the store; stock is not tracked.

About this part

Robinson Racing Extra Hard Steel 5mm Bore .8 Mod Pinion Gears fit brushless motors with a 5mm shaft and are intended for use with the Traxxas E-Maxx model #3905. These will also work with standard size brushless motors when used with the RRP1200 reducer sleeve, making them an excellent choice for the Traxxas Slash 4x4.

Reviews3.6 · 5 reviewsacross all options

The Stigon Robinson Racing Extra Hard Steel .8 Mod Pinion Gear w/5mm Bore (15T)

If you read the description, it says "These will also work with standard size brushless motors when used with the RRP1200 reducer sleeve, making them an excellent choice for the Traxxas Slash 4x4."...you shouldnt give a product a poor ranking because you didnt take the time to read.

12 found this helpful
Brian Rodenburgon Robinson Racing Extra Hard Steel .8 Mod Pinion Gear w/5mm Bore (13T)

I dont know what this guy is talking about. I have had awesome luck with the 5mm bore pinions. They Never break or slip off. You never strip the grub screw cause it is 2 sizes bigger. All in all I have been running my truck real hard for about 4 months now and have never once had an issue.

6 found this helpful
AnonymousVerified owneron Robinson Racing Extra Hard Steel .8 Mod Pinion Gear w/5mm Bore (15T)

Becarefull : This pinion need another product to work on a slash 4x4. the other product is : http://www.amainhobbies.com/product_info.php/cPath/1_24_253_1870/products_id/25015/n/Robinson-Racing-5mm-To-1-8-Reducer-Sleeve

1 found this helpful
Michel PelletierVerified owneron Robinson Racing Extra Hard Steel .8 Mod Pinion Gear w/5mm Bore (14T)

Excellent product, I recommend it. Amain is the best for spare parts.

Jon Robinson Racing Extra Hard Steel .8 Mod Pinion Gear w/5mm Bore (13T)

Purchased this + Reducer sleeve for Slash 4x4 Set screw kept slipping off the motor shaft no matter how tight I set it, used blue loctite and same result, the pinion slid off and carved a pinion sized hole into my cover and chassis. Also the teeth sawbladed after 3 batteries on a plastic traxxas gear so I don't know how RR claims this to be hardened steel. Save your money and look elsewhere if you have a slash

What reviewers say

Reviewers give this 5mm bore steel pinion mixed ratings, averaging about 3.8 out of 5 across five reviews. Several positive reviewers report long-term use without the pinion slipping or breaking, and praise the grub screw sizing. Negative reviewers report the set screw slipping off the motor shaft even with thread-locker, and teeth wearing quickly when run with a plastic Traxxas gear. Two reviews note that a reducer sleeve is needed for a Slash 4x4 with standard-size brushless motors. Variants reviewed include 13T, 14T and 15T. Reviewers disagree mainly on durability and whether the steel is hardened in practice.

  • + Long-term use without slipping or breaking
  • + Grub screw holds well on 5mm bore
  • + Good value for spare parts
  • − Set screw slips on motor shaft
  • − Teeth wear quickly with plastic gear
  • − Needs reducer sleeve for Slash 4x4
Summary generated from the reviews above.

Builds using this part

No builds use this part yet — add it to yours from the build editor.