troutshark
Newbie
So I sold my Bronco to a buddy and decided to get the new Sport as I didn't care for the 2 speed and locking diffs but thought the truck had a lot of potential. Got my Sport in yesterday along with a giant pile off hopup parts. Woohoo! I didn't even drive it, I tore it apart and rebuilt it the rccrawler way. Hop up everything! Metal axle housings, all the brass stuff, OD and UD gears, HH servo, HW1080 esc, Predator compound Hyraxes, LCG battery tray, 80mm shocks for the lower stance, steelies, and a Bronco body with lights etc... It took me all night but I got it done.
Then I drove it.... Much anger and sadness.... :evil:
So I guess Traxxas thought it needed it to be fast. Feels like it's stuck in 2nd gear. It'll pop a wheelie. Sigh, I have other trucks for that stuff.
Anyways, RTFM so I broke out the manuals. I'm not happy if I have to read a manual. Just saying
Comparing the gearing compatibility charts of the regular TRX-4 to the new Sport I see that it isn't too big of a deal. They used the low gear from the 2 speed trans but switched to the 39t spur with a 17t pinion. That's 39t/17t x 15.8 low gear for a Final gear ratio of 36.25.
The regular 2 speed TRX-4 uses a 45t spur with a 11t pinion. That's 45/11 x 6.32 high gear for a 25.85 Final gear ratio in 2nd. The low gear ratio is 45/11 x 15.8 for a Final gear ratio of 64.64. I like my crawlers geared 60 plus, so that's what I was wanting.
It's an easy enough fix. So if you are expecting a slow crawling experience from your new Sport like 1st gear in the original TRX-4 you will need a 45t spur TRA8053 and a 12t pinion TRA6747. If I would have known, I would have ordered them with my truck in the first place. Hopefully, I'll keep somebody else who likes their trucks all crawlerly and slow from cussing their new Sport like me.
What struck me as really odd though, if you compare the two charts, the 2 speed chart for low gear lists the gear ratio of 36.25 that the Sport uses as "Not recommended for the stock motor". Since that's exactly what the Sport chart recommends as ideal or whatever, I thought I'd test that out to see if it's fine like Traxxas says.
So for SCIENCE! I stuck the stock esc back in the truck and pretended my all brassed out heavy metal truck was light again. I ran it around like a basher on 3s for about 15 minutes in 95+ degrees of beautiful sunshine before it shut down. Motor temps were over 160F and the ESC was 150F. Yeah, it's not a fair test as it's really heavy but that's not a healthy gear ratio IMO. At least for the stock motor. I'd definitely recommend changing the gears or using a lower turn motor to keep temps down. The electronics survived my little test but I doubt they would for long.
If you plan on running a higher kv brushless combo in the Sport as folks are prone to do, it might be trouble without changing gear ratios. A low kv Puller Pro or maybe a Revolver might work. I'm sure Mr. Holmes will have some motor recommendations for us soon. "thumbsup"
It's a really nice little crawler but i think they screwed up on that pinion and spur combo. Oh well, my box full of Traxxas stock parts had a little bit of space left in it. ;-)
Then I drove it.... Much anger and sadness.... :evil:
So I guess Traxxas thought it needed it to be fast. Feels like it's stuck in 2nd gear. It'll pop a wheelie. Sigh, I have other trucks for that stuff.
Anyways, RTFM so I broke out the manuals. I'm not happy if I have to read a manual. Just saying
Comparing the gearing compatibility charts of the regular TRX-4 to the new Sport I see that it isn't too big of a deal. They used the low gear from the 2 speed trans but switched to the 39t spur with a 17t pinion. That's 39t/17t x 15.8 low gear for a Final gear ratio of 36.25.
The regular 2 speed TRX-4 uses a 45t spur with a 11t pinion. That's 45/11 x 6.32 high gear for a 25.85 Final gear ratio in 2nd. The low gear ratio is 45/11 x 15.8 for a Final gear ratio of 64.64. I like my crawlers geared 60 plus, so that's what I was wanting.
It's an easy enough fix. So if you are expecting a slow crawling experience from your new Sport like 1st gear in the original TRX-4 you will need a 45t spur TRA8053 and a 12t pinion TRA6747. If I would have known, I would have ordered them with my truck in the first place. Hopefully, I'll keep somebody else who likes their trucks all crawlerly and slow from cussing their new Sport like me.
What struck me as really odd though, if you compare the two charts, the 2 speed chart for low gear lists the gear ratio of 36.25 that the Sport uses as "Not recommended for the stock motor". Since that's exactly what the Sport chart recommends as ideal or whatever, I thought I'd test that out to see if it's fine like Traxxas says.
So for SCIENCE! I stuck the stock esc back in the truck and pretended my all brassed out heavy metal truck was light again. I ran it around like a basher on 3s for about 15 minutes in 95+ degrees of beautiful sunshine before it shut down. Motor temps were over 160F and the ESC was 150F. Yeah, it's not a fair test as it's really heavy but that's not a healthy gear ratio IMO. At least for the stock motor. I'd definitely recommend changing the gears or using a lower turn motor to keep temps down. The electronics survived my little test but I doubt they would for long.
If you plan on running a higher kv brushless combo in the Sport as folks are prone to do, it might be trouble without changing gear ratios. A low kv Puller Pro or maybe a Revolver might work. I'm sure Mr. Holmes will have some motor recommendations for us soon. "thumbsup"
It's a really nice little crawler but i think they screwed up on that pinion and spur combo. Oh well, my box full of Traxxas stock parts had a little bit of space left in it. ;-)
