Hobao OB4 electric revisited.
06-03-2014, 01:32 PM
#1
Hong Nor OB4 electric revisited.
A long time ago I had a nitro TC, electrics were available but 5 minutes runtime were not inviting, we're talking 2400Nicads here 
So a couple months ago I saw a cool TC, saddle pack, centered motor, PBS suspension...Absolutely different from the Tamiya 415 and sequent cars(except the Xray T1 for obvious reasons). Well, it came with brushed electronics and I really liked it because it's so different and I think I can do something very special using a shorty battery. I'm going to add a couple pics and show my progress here.
The plan is to use a BL system with a shorty, make a new chassis and maybe enter some competition with it. If anyone has tips and tricks, chassis ideas, etc..just say.
Stay tuned
So a couple months ago I saw a cool TC, saddle pack, centered motor, PBS suspension...Absolutely different from the Tamiya 415 and sequent cars(except the Xray T1 for obvious reasons). Well, it came with brushed electronics and I really liked it because it's so different and I think I can do something very special using a shorty battery. I'm going to add a couple pics and show my progress here.
The plan is to use a BL system with a shorty, make a new chassis and maybe enter some competition with it. If anyone has tips and tricks, chassis ideas, etc..just say.
Stay tuned
Last edited by 30Tooth; 06-09-2014 at 12:49 PM.
06-05-2014, 12:17 PM
#2
sorry, maybe I missed something,
Why is this thread called "Hobao OB4 electric revisited."???
Why is this thread called "Hobao OB4 electric revisited."???
06-06-2014, 03:11 AM
#3
No need to be sorry. Being a non-native English speaker I thought it was kind of fitting, because the OB4 is old and forgotten and now there is interest in out of ordinary looking TC's. So I'm converting the old girl to BL and LiPo saddle pack, new technology with the concept of PBS suspension and saddle packs on a electric TC. Maybe I should of waited a bit more to gather more pics and progress?
Bonus info, I've found that Kyosho ZX5 bladders work on OB4 shocks, you can use the ZX5 top shock mounts which are 1mm shorter but way stronger and are drop in replacement.
Bonus info, I've found that Kyosho ZX5 bladders work on OB4 shocks, you can use the ZX5 top shock mounts which are 1mm shorter but way stronger and are drop in replacement.
06-06-2014, 04:48 AM
#4
If I recall correctly, the OB4 has an issue with the design of the front uprights: There is no inner "lip" to prevent the (unflanged) bearings from moving sideways. It might be possible to use flanged bearings, or modify the upright.
This was one of several issues with the car that made me finally give up on it. The concept was neat, but the execution... not so much.
This was one of several issues with the car that made me finally give up on it. The concept was neat, but the execution... not so much.
06-06-2014, 06:08 AM
#5
If I recall correctly, the OB4 has an issue with the design of the front uprights: There is no inner "lip" to prevent the (unflanged) bearings from moving sideways. It might be possible to use flanged bearings, or modify the upright.
This was one of several issues with the car that made me finally give up on it. The concept was neat, but the execution... not so much.
This was one of several issues with the car that made me finally give up on it. The concept was neat, but the execution... not so much.
BTW, sir you have a PM.
06-06-2014, 06:53 AM
#6
I ran the OB4 as a "poor man's XRay" until I bought my first T1.
On of the biggest improvements on the OB4 would be updating the front to a gear diff. I don't know of any that fit, but it wouldn't surprise me if there are diffs from other cars that could be kluged in.
06-06-2014, 07:06 AM
#7
Okay, I plead old age for bad memory! Maybe I broke through the lip with my many encounters with the boards. Or maybe the uprights were updated to fix the problem.
I ran the OB4 as a "poor man's XRay" until I bought my first T1.
On of the biggest improvements on the OB4 would be updating the front to a gear diff. I don't know of any that fit, but it wouldn't surprise me if there are diffs from other cars that could be kluged in.
I ran the OB4 as a "poor man's XRay" until I bought my first T1.
On of the biggest improvements on the OB4 would be updating the front to a gear diff. I don't know of any that fit, but it wouldn't surprise me if there are diffs from other cars that could be kluged in.
If all else fails there's the nitro OB4 gear diffs. Diff is approximately 17.7mm bearing to bearing (inner bulkhead measure)and has a 35 tooth count if not mistaken, too narrow for today's standards afaik.
06-06-2014, 02:50 PM
#9
And so the hunt begins, JL10e gear diffs will be. Not that I have any sort of problems with the stock ball diffs but plastic outdrives, it's just living dangerously. Oh and JL10e drift front uprights were updated, now have 3 ackerman positions. The complete JL10e steering setup should reduce bump steer, I had to shim the rack up 3mm and mount the balls beneath the upright.
06-06-2014, 04:52 PM
#10
Correction to my previous post: The OB4 Mid/JL10 Drift gear diff uses the same gears as the Nitro OB4, but the housing, pulley, and outdrives have different part numbers. I think the Mid/Drift diff might have the best chance to fit properly.
I agree about plastic outdrives. The first TC I bought was a TC3, and when I saw that the outdrives were plastic, I vowed to never buy another Associated car. Fortunately there were steel upgrades available for it.
I agree about plastic outdrives. The first TC I bought was a TC3, and when I saw that the outdrives were plastic, I vowed to never buy another Associated car. Fortunately there were steel upgrades available for it.
06-07-2014, 10:54 PM
#12
URL=http://s185.photobucket.com/user/alcyon2sp/media/Mobile%20Uploads/20140513_162044_zpsrm45hav0.jpg.html]
[/URL]The ob4 is a lot like the rclab 77 . I have done an experiment similar to what you plan to do..on my same era kawada sv10 II. I used the original suspension, bulkheads top decks motor mount...i designed a new super narrow lipo chassis, mounting for vbc floating servo mount to make the flex equal on both sides.i also was able to fit trf417 gear diffs which changed the ratio. Because of that i used 3racing 17t top pulleys compared to the originals 16t. The ratio was 2.25. Now its 2.1764.
Before this there was a guy with a bd7 who used 7200mah batteries who kept beating the crap out of my kawada . Just 2 nights ago i went up against his bd7..still i was using 4200mah shorty pack and guess what..he ate my dust hig time ! The centered mass design coupled with equal flex left and right transformed my kawada into a nuetral handling tc with a lot of steering without rear end washing out.
the funny thing was every week he would keep telling me not to suffer and just buy a modern car. Well after i beat him he just kept quiet and kept trying to fix his car..when there was nothing wrong with it actually .
Last edited by alcyon; 06-08-2014 at 01:09 AM.
06-08-2014, 03:17 PM
#15
*snip*
The ob4 is a lot like the rclab 77 . I have done an experiment similar to what you plan to do..on my same era kawada sv10 II. I used the original suspension, bulkheads top decks motor mount...i designed a new super narrow lipo chassis, mounting for vbc floating servo mount to make the flex equal on both sides.i also was able to fit trf417 gear diffs which changed the ratio. Because of that i used 3racing 17t top pulleys compared to the originals 16t. The ratio was 2.25. Now its 2.1764.
Before this there was a guy with a bd7 who used 7200mah batteries who kept beating the crap out of my kawada . Just 2 nights ago i went up against his bd7..still i was using 4200mah shorty pack and guess what..he ate my dust hig time ! The centered mass design coupled with equal flex left and right transformed my kawada into a nuetral handling tc with a lot of steering without rear end washing out.
the funny thing was every week he would keep telling me not to suffer and just buy a modern car. Well after i beat him he just kept quiet and kept trying to fix his car..when there was nothing wrong with it actually .
The ob4 is a lot like the rclab 77 . I have done an experiment similar to what you plan to do..on my same era kawada sv10 II. I used the original suspension, bulkheads top decks motor mount...i designed a new super narrow lipo chassis, mounting for vbc floating servo mount to make the flex equal on both sides.i also was able to fit trf417 gear diffs which changed the ratio. Because of that i used 3racing 17t top pulleys compared to the originals 16t. The ratio was 2.25. Now its 2.1764.
Before this there was a guy with a bd7 who used 7200mah batteries who kept beating the crap out of my kawada . Just 2 nights ago i went up against his bd7..still i was using 4200mah shorty pack and guess what..he ate my dust hig time ! The centered mass design coupled with equal flex left and right transformed my kawada into a nuetral handling tc with a lot of steering without rear end washing out.
the funny thing was every week he would keep telling me not to suffer and just buy a modern car. Well after i beat him he just kept quiet and kept trying to fix his car..when there was nothing wrong with it actually .
I see you can mount the battery way in a place I can't, the belt gets in the way. I'm thinking of making two chassis, one for saddle pack and another for a shorty. The saddle one will be similar to stock but without the cut outs for Sub C cells, I just have to make 2 cradles and a new top deck because the battery plugs don't clear the top deck. The shorty one will have the battery mounted lengthwise and thanks to your idea will use a floating servo mount to flip the servo to the left side, so I can mount the battery more inward. I'm just waiting for the completion of the pin router and G10 sheets.