derv_scaler 17 Posted October 23, 2014 Hi All, I've just bought myself a re-re Brat kit (supplied without ESC) and am in the process of building it up and wanted to know what options I have for locking the diff and possibly strengthening the transmission. I've done some research and seen various methods, so far the faviourite one being to drill and tap the diff output cups and thread lock an M3 bolt down the centre to hold the cups together, as you'd find in a ball diff on any other car, this would have an added benefit of helping prevent the casings spreading under power. The intermediate gear in the transmission is very narrow, how do these hold up? I had intended to run a mild brushless setup, more for better run times than outright power so bought a Turnigy 3000kv motor/esc/card combo from HK, but having seen the weak looking intermediate gear I'm now having my doubts. I've got the option of running the stock silver can motor and a Tamiya 101 ESC (Already had it, hence buying the kit without an ESC) along with a low voltage alarm/5000mah Lipo. Any advice welcome Share this post Link to post Share on other sites
Quandry 378 Posted October 23, 2014 I'm running mine with a GT motor and the high speed gear set with 2s Lipo. It's a lot of fun! I have overworked the front suspension a few times even still on brushed... Share this post Link to post Share on other sites
derv_scaler 17 Posted October 23, 2014 Sounds like fun, how's the transmission holding up so far? Front suspension is next on the list, I'll be fabricating some shock towers and running something that actually damps in place of the pogo front end My first proper RC car was the original Brat, loved it so much I bought a 1:1 version, this was way back in the early 90's, it's probably rusted away now... EDIT - Just spotted that I've posted this in the vintage area, sorry about that - too keen! Share this post Link to post Share on other sites
Quandry 378 Posted October 23, 2014 No issues on transmission so far (touch wood). When I mentioned the front end before, the weak point I really see is the single nut/bolt that holds the wheel arm together on each side. Due to the amount of bouncing around when jumping or even just plane driving, it can come loose very easilly. Needs a lot of loctite to stay locked in and also there's flex there affecting geometry. Anyway for a fun basher it's no problem although it occured to me that a brushless motor might push that limitation over the edge. Was your real Brat a Brat or a Brumby?? (Aussie version of the Brat). I wanted a real one when I was growing up in Aus but got a Celica instead but it was a real kick buying a Tamiya Brat after all these years. Share this post Link to post Share on other sites
derv_scaler 17 Posted October 23, 2014 Ah yes, the geometry will be all over the place too, I've got a couple of ideas that may help, but need to try them/test them out first, the whole front end isn't very precise, but that's half the fun My Brat was actually an MV (UK version) with single headlilghts, I had an early Subaru estate shortly after, I paid the princely sum of £30 for it and found £13 in change under the seats when cleaning it - obviously this was a loooong time ago. I had a quick look on google images, closest I can find is: And Share this post Link to post Share on other sites
Quandry 378 Posted October 23, 2014 Ah very cool, I didn't know that there were Brat's in the UK. I must run a search over here and see if there's any going. regarding the steering on the Brat, I found mine to be a bit skittish with the extra power, although I added a SkyRC gyro (http://www.modelsport.co.uk/skyrc-gyro-for-rc-cars/rc-car-products/384586) and it improved the tracking, oversteer tendencies, and also control under hard acceleration. The GT motor has OK power but putting in a brushless I would say the gyro would be a must. It would also be nice to get a ball diff upgrade but my understanding is they are pretty hard to come by for that era of car (Hotshot/Frog/Brat etc). Let me know if you find anything though! Share this post Link to post Share on other sites
MadInventor 3886 Posted October 23, 2014 Hi All, I've just bought myself a re-re Brat kit (supplied without ESC) and am in the process of building it up and wanted to know what options I have for locking the diff and possibly strengthening the transmission. I've done some research and seen various methods, so far the faviourite one being to drill and tap the diff output cups and thread lock an M3 bolt down the centre to hold the cups together, as you'd find in a ball diff on any other car, this would have an added benefit of helping prevent the casings spreading under power. The intermediate gear in the transmission is very narrow, how do these hold up? I had intended to run a mild brushless setup, more for better run times than outright power so bought a Turnigy 3000kv motor/esc/card combo from HK, but having seen the weak looking intermediate gear I'm now having my doubts. I've got the option of running the stock silver can motor and a Tamiya 101 ESC (Already had it, hence buying the kit without an ESC) along with a low voltage alarm/5000mah Lipo. Any advice welcome If you just want a locked diff, the original Brat with the 380 was supplied with a solid rear axle and no diff. Perhaps it is possible to source the original parts, although I don't know if they would be compatible with the re-re drive cups. Share this post Link to post Share on other sites
derv_scaler 17 Posted October 26, 2014 Some interesting options there, I'll do some research. I was thinking I was sure my first Brat had a locked diff, but being so long ago I couldn't remember 100%, went off and downloaded the manual and confirmed it had a locked rear end, but it's done with a hex insert on the diff gear. I've just run a couple of packs on it with an open diff and no bodywork, great fun but seriously needs something doing to the diff, even with the supplied silver can it's lighting up the inner wheel a lot. Share this post Link to post Share on other sites
i_am_scarecrow 913 Posted October 31, 2014 Is it a simple thing converting from the 380 to a bigger motor? I'm thinking a sport tuned myself. Share this post Link to post Share on other sites
derv_scaler 17 Posted October 31, 2014 My current Brat is a ReRe, so came with a 540, but I would imagine it would just be a case of fitting the correct pinion to a 540 to replace a 380, in a similar manner to the Grasshopper. Share this post Link to post Share on other sites
i_am_scarecrow 913 Posted October 31, 2014 Ahh, I didn't know the re re's came with a 540, you learn something new every day! Share this post Link to post Share on other sites
derv_scaler 17 Posted October 31, 2014 I must say that with a set of ball races and a silver can 540 run in using the 'water in a cup' method it seems quite fast. Share this post Link to post Share on other sites
