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View Full Version : r2 tranny and 7t puller



jrunner
03-31-2008, 01:14 PM
quick question, i'll be getting a r2 tranny for a deal i got w/ a tuber.

will that r2 tranny stand up to a 7t puller motor ?

jay

ecoli
03-31-2008, 03:04 PM
You bet. A lot of people on rccrawler using that same combo. However, I've heard the gearing is a little high on the r2 tranny for the cobalt motor. May want to consider selling it and buying something like an Axial transmission, where you can at least change the spur gear in it.

colonelangus
03-31-2008, 06:29 PM
wow thats news to me .i have heard and seen of them coming apart due to excesive power/torque .they sell a heavy duty upgrade gear kit for a reason.if they dont stand up to brushless lopo's systems i cant see them standing up to the cobalt either ..
just another perspective .

mrb
03-31-2008, 06:37 PM
too much for the r2, look to replace gears if you do.

Get the r2v2 if your adament. Has stronger gears.

jrunner
04-01-2008, 02:16 AM
You bet. A lot of people on rccrawler using that same combo. However, I've heard the gearing is a little high on the r2 tranny for the cobalt motor. May want to consider selling it and buying something like an Axial transmission, where you can at least change the spur gear in it.

im not to familar w/ these trannys. when u mean high ratio for the gear meaning i'll have alot of speed ?

ecoli
04-01-2008, 09:31 AM
im not to familar w/ these trannys. when u mean high ratio for the gear meaning i'll have alot of speed ?

Yes. From what I've seen, John generally has recommended gearing with as high a spur gear and as small a pinion gear as possible. This allows lots of low end torque and, with the cobalt, still some decent wheelspeed. With the R2 tranny, you're stuck with the gear ratio it comes with, you can only change your pinion gear.

Look up Kamikaze's rig on rccrawler. He's got a video of an R2 tranny with a cobalt 7t in his blackjack which is extremely heavily weighted in the wheels (something like a pound in each front wheel). On carpet, he still pulls wheelies at WOT. Not really necessary for crawling! Keep in mind that was with, I think, a 3s lipo pack. If you're running less power, you might get away with the gear ratio you have in the R2. The flipside of that is that your runtimes will be down (the cobalt is apparently a bit of a power pig).

Again, you could easily sell your R2 and buy a new Axial transmission. Might be the way to go!

jrunner
04-01-2008, 10:18 AM
Yes. From what I've seen, John generally has recommended gearing with as high a spur gear and as small a pinion gear as possible. This allows lots of low end torque and, with the cobalt, still some decent wheelspeed. With the R2 tranny, you're stuck with the gear ratio it comes with, you can only change your pinion gear.

Look up Kamikaze's rig on rccrawler. He's got a video of an R2 tranny with a cobalt 7t in his blackjack which is extremely heavily weighted in the wheels (something like a pound in each front wheel). On carpet, he still pulls wheelies at WOT. Not really necessary for crawling! Keep in mind that was with, I think, a 3s lipo pack. If you're running less power, you might get away with the gear ratio you have in the R2. The flipside of that is that your runtimes will be down (the cobalt is apparently a bit of a power pig).

Again, you could easily sell your R2 and buy a new Axial transmission. Might be the way to go!


i have seen kamikaze rig. and its pretty stout. well im wanting the high gear ratio for some build that im doing. but i want it to last long, guess i'll decided what i want to do when im almost finish. thanks for the info guys.

dittohead
04-02-2008, 06:36 PM
Yes. From what I've seen, John generally has recommended gearing with as high a spur gear and as small a pinion gear as possible. This allows lots of low end torque and, with the cobalt, still some decent wheelspeed. With the R2 tranny, you're stuck with the gear ratio it comes with, you can only change your pinion gear.

Look up Kamikaze's rig on rccrawler. He's got a video of an R2 tranny with a cobalt 7t in his blackjack which is extremely heavily weighted in the wheels (something like a pound in each front wheel). On carpet, he still pulls wheelies at WOT. Not really necessary for crawling! Keep in mind that was with, I think, a 3s lipo pack. If you're running less power, you might get away with the gear ratio you have in the R2. The flipside of that is that your runtimes will be down (the cobalt is apparently a bit of a power pig).

Again, you could easily sell your R2 and buy a new Axial transmission. Might be the way to go!

You have it backwards, the R2 is the LOWEST geared trans available, but its really weak, a 16t pinion fits in it and it makes a huge difference in wheelspeed though, which is needed for that trans. The R2 with the 8t pinion is too slow for any motor on the market(even on 3s lipo) except the cobalt, but i bet its still only marginal. Wheelspeed is definitely nessessary in crawling IMO. I would only run an axial trans if you get the VF billet output shafts, the stockers are crap, i have ruined 4 of them so far with regular old lathe motors. In reality, the old stampede trans is the probably the strongest trans out there (that fits easily into a 2.2 rig), especially the VXL version, all steel gears! Too bad they are so bulky