These are parts for your 540 brushed motor. These are standard TorqueMaster, TrailMaster, and CrawlMaster parts.
*Sold in pairs
The X spring is an ideal tension for best motor life, it balances electrical wear with mechanical wear.
The XX spring works well off road and prevents brush bounce while
encouraging better low speed drag brake. This is the stock spring for Holmes Motors.
The XXX spring is best suited for dirty conditions and water use to prevent brush hydroplaning, but motor wear is accelerated.
*X Spring = 7.2 oz
*XX Spring = 10.0 oz
*XXX Spring = 14.2 oz