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Old 12-18-2014, 02:29 PM   #16
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Hi guys,

I'll be rebuilding the RTR diffs soon and I was wondering if anyone has some recommendations for diff fluids for on-road speeders. I read on-road racers typically use heavy or locked front diff and around 10k cSt rear diff. I haven't decided on ESC yet, but I think RTR weight will be about 4.5 kg and gearing 90 mph and up (depending on what motor will be happy to pull for continuous use). I'll be running 2 rear toe (instead of stock 3) with the IF124B barces, to free up some speed, but have no idea if I should compensate that with a bit of a lighter rear diff fluid in order not to lose too much rear end stability. Any ideas?

I'm using 20k/10k (FR/RR) in my Truggy, but the 10k is a bit on the light side and it seems to be leaking, probably due to getting hot. I also have some 40k cSt and 500k WT (Traxxas stuff, read someone reporting it to be actually thinner than his 300k cSt FG brand fluid), so I think I'm gonna rebuild the GT2 diffs with the 500k WT front and 40k cSt rear.

You guys think that would be a good starting point for good balance between straight line stability and handling (I'm not talking about serious track use, I just don't want it to be a straight line speed runner only that does not turn well)?



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Old 12-20-2014, 11:33 PM   #17
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isnt there a cst reading on the 500w? my 500000 is almost like......uhm....well it hardly runs when you use it.
remember the thicker the oil the more diff action you get, the lighter you go the more diff action so consider that when choosing. center diff is also crucial.
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Old 12-23-2014, 10:37 AM   #18
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Quote:
Originally Posted by Dr_T View Post
Hi guys,

I'll be rebuilding the RTR diffs soon and I was wondering if anyone has some recommendations for diff fluids for on-road speeders. I read on-road racers typically use heavy or locked front diff and around 10k cSt rear diff. I haven't decided on ESC yet, but I think RTR weight will be about 4.5 kg and gearing 90 mph and up (depending on what motor will be happy to pull for continuous use). I'll be running 2 rear toe (instead of stock 3) with the IF124B barces, to free up some speed, but have no idea if I should compensate that with a bit of a lighter rear diff fluid in order not to lose too much rear end stability. Any ideas?

I'm using 20k/10k (FR/RR) in my Truggy, but the 10k is a bit on the light side and it seems to be leaking, probably due to getting hot. I also have some 40k cSt and 500k WT (Traxxas stuff, read someone reporting it to be actually thinner than his 300k cSt FG brand fluid), so I think I'm gonna rebuild the GT2 diffs with the 500k WT front and 40k cSt rear.

You guys think that would be a good starting point for good balance between straight line stability and handling (I'm not talking about serious track use, I just don't want it to be a straight line speed runner only that does not turn well)?



Dr T...on my Inferno GT1 VE track car running a mamba monster esc & motor I only use Kyosho diff oil... Center 50K, Front 120K & rear 30K...car runs faster laps than my GT1MP777 Nitro car >>>
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Old 12-23-2014, 10:45 AM   #19
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Cool project, I'm interested in seeing how it shakes out!
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Old 12-28-2014, 02:35 PM   #20
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Quote:
Originally Posted by Reaper1ct View Post
isnt there a cst reading on the 500w? my 500000 is almost like......uhm....well it hardly runs when you use it.
remember the thicker the oil the more diff action you get, the lighter you go the more diff action so consider that when choosing. center diff is also crucial.
No cSt, Traxxas only mentions "weight", ... and of course that I should rinse my mouth if I eat it . Here's a post from a German website where someone actually says his 500k WT Traxxas fluid is thinner than his 300k CPS=cSt FG (1/5 scale brand) fluid: http://www.rcindependent.com/wbb3/in...441#post723441.

I'll be running a spool in the center, so ∞ cSt . In my Truggy, I use some non RC-specific "industrial" 2.000.000 cSt fluid in the center, as with the 500k Traxxas stuff, there was still so much diff action, the diff ran hotter (~85C) than I liked it to.



Quote:
Originally Posted by Yb2fast View Post
Dr T...on my Inferno GT1 VE track car running a mamba monster esc & motor I only use Kyosho diff oil... Center 50K, Front 120K & rear 30K...car runs faster laps than my GT1MP777 Nitro car >>>
Thanks for the reference! In the front that's relatively close to what XO-1 comes out of the box with too, 100k/10k (F/R), but a bit heavier in the back. I like the idea of going a bit heavier. I will start out with the 500k WT Traxxas stuff ~ <300k cSt front and 40k cSt rear. I was a bit afraid that might be too high in the back, but if your 30k rear is working well for you on track, the 40k should not be too noticeably heavy for my fooling around at the parking lot .

Quote:
Originally Posted by ViperZ View Post
Cool project, I'm interested in seeing how it shakes out!
Thanks! I like your sig ... same here

Haven't gotten much work done lately, still gathering parts and ideas. Got the Ofna DM-1 center spool mount as an alternative spur-to-pinion adapter, or plan B, would the XO-1 cushdrive option fail. Thought I could run it with all the 44T-49T Ofna spurs, but the 44T is too small and seems to require the newer X3 spool mount. The DM-1 uses an 8 mm tranny shaft, so I'll make a little bore reducer to fit it to the 6 mm motor shaft of the 5682.





Also ordered a not too expensive 30T 6 mm bore pinion on aliexpress: http://www.aliexpress.com/item/Spur-...954767631.html, which I can use as a spur on the 6 mm dia tranny shaft, to increase gearing options a bit. I would have liked the idea of the 24T pinion as a spur, to avoid the necessity of those insane big pinions, but unfortunately I need at least ~39 mm shaft-to-shaft distance, or else the motor will hit the rear chassis brace. It does provide an option for some very extreme gearing though, 49/24 and 54/24 (pinion/spur) gearing fits and yields 225 kph (140 mph) and 248 kph (154 mph) no-load speed respectively, but I have little illusion the poor Turnigy motor and batteries will appreciate that very much.



New gearing chart - the Ofna 49T pinion on the 30T aliexpress spur, yields 180 kph (112 mph) no-load wheel-speed at nominal Voltage. Note that green just means it fits, and not necessarily that it's wise to do .
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Old 01-01-2015, 04:12 PM   #21
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Happy new year guys!

No updates, but if anyone's interested: Mamba XL2 is selling for 145 bucks now at Amazon. Decided I couldn't wait any longer and have one on the way now ... I guess that actually IS an update .

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Old 01-04-2015, 01:01 PM   #22
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http://www.rctech.net/forum/members/...hoto-2-100.jpg

What is the part number for the diff replacement axle and the outdrives,
or what is the kit they are taken from ?
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Old 01-05-2015, 07:39 AM   #23
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http://www.rctech.net/forum/members/...hoto-2-100.jpg

What is the part number for the diff replacement axle and the outdrives,
or what is the kit they are taken from ?
It's the "old" KYOIG108 2-Speed Shaft Set, you have to use the KYOIG101 100mm Center/Front Driveshaft with it. You could also use the new KYOIGW008-01 shaft, but if I remember correctly, that's used with the shorter (95mm?) driveshaft.

The IG108 shaft uses a 7 mm e-clip on the front to secure the bearing, and I used a little piece of PVC tube to secure the rear bearing against the outdrive:



IG108:


IGW008-01:
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Old 01-27-2015, 09:22 AM   #24
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No significant results yet (build basically has to start still ), but at least most of the parts are in now:


ESC, servo, BEC. The $10 5682 motor, together with the sale XL2, yields a $155 motor/ESC combo: not bad .


Fat (and messy) piggy .


Size comparison with my 8T.

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Old 03-03-2015, 03:33 AM   #25
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Little update just to confirm both me and the project are still alive

Didn't have much luck yet trying to make the Traxxas cushdrive key to work for the XO-1 spur to pinion mod... with a lot of effort I managed to drill a 2.5 mm hole in it (HSSE Cobalt drill), but then it cracked during tapping the M3 thread. The material is extremely hard and it took very long to drill the hole, maybe because of that the hole needed to be a bit bigger diameter for the thread?

Also good news: I stumbled on a cheap $15 Parma buggy body on Amain that fits the GT2 pretty well - although it is going to be quite tight with the 5Ah 6S batteries. Not the prettiest, but if I want something fancy to look nice on the shelf, I can always get an Audi R8 body for it .






Diffs: front 500k (TRX WT), rear 40k cSt.


2 rear toe brace.


2 rear toe brace.


Parma #1222 X-Citer Buggy Body.





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Old 03-30-2015, 01:27 PM   #26
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Before...


After.


Left: el-cheapo chop-shop big-bore shocks (DF-models Mali street racer); right: (de-anodized) stock GT2 shocks.




Front would fit...


But rear wouldn't.
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Old 04-01-2015, 05:10 AM   #27
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Little step by little step :


DIY bore reducers; Alu tube had crappy tolerances (uneven wall thickness, causing gear wobbling), steel hydraulic tubing seems accurate enough.


PVC spacer to keep rear bearing in place.


49/36 gearing. Spur can be further reduced by using pinions instead.
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Old 04-01-2015, 07:55 AM   #28
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And a little updated gearing chart (no-load wheel-speeds in kph at nominal Voltage), assuming I can't make the XO-1 cushdrive work and will be limited to using OFNA DM-1 (47-49T) and GTP2 (51T, available in both nylon and steel) spurs as pinion. Red cells won't fit (shaft-to-shaft distance too small).



I already have the 30T 6 mm bore pinion from Aliexpress to use as spur on the spool, but it is a bit on the heavy side: 87 g, ~1.5 times the weight of the complete spool with 36T plastic Revo spur.





For the benefit of anyone reading along, the OFNA part no. for the spur-to-big-pinion alternatives:



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Old 04-28-2015, 09:47 AM   #29
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Felt I needed to lower the battery tray a bit in order to fit big fat basher batteries under the buggy style body. Got some advice from Koval on how to mill the material of his tray and went ahead, ...low-tech manual-style . Almost ruined it trying to cheap-out and doing it without proper clamps, but after getting some good clamps, it actually went quite well.

7S wasn't part of the original plans, but I saw this and could not refuse:


The motor is actually rated 6S only, but with enough gearing it'll never see the full 7S RPM anyway, so I think I'll take my chances on that.




Before.


2-flute 10 mm mill @ ~2000-2500 RPM (normal hand-drill)


After


Result


Velcro-slots in the side-guard


Not bad at all .


5.0 Ah 7S Turnigy HD - corner will push out body slightly, but should still work.


5.0 Ah 6S Turnigy HD - fits nicely within body; and yes, pic was taken with a potato.


Body still needs some trimming, but you get the idea.


Switch-over from EC5 to some more manly XT150 connectors (6 mm bullets).


More DIY-ing.


Still under construction.
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Old 04-30-2015, 10:07 PM   #30
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Wow this is so insanely cool. Where did u get that motor for $10?
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