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Schumacher
(http://www.oople.com/forums/forumdisplay.php?f=46)
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Got you! Cheers for clearing that up!
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so this is what i gathered,
-just swaping the shocks to the back does not change the wheel base -swaping the shocks and arms shortens the base by 6mm -swaping shocks, arms and blocks does???? |
swapping shocks arms and blocks keeps wheel base simular.:thumbsup:
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the kit is raccomanded for use with alloy upper rear trasmission...
but if take for mount on the standard plastic upper rear trasmission?:eh?: |
Well I have done a little bench testing and to be honest, I'm not quite sure of exactly which is the right way to go :confused:
The problem with just swapping the arms over (as per the Schuie mod) is it makes a big difference to wheelbase (which may not be a big deal) but it increases the driveshaft sweep enormously, in fact more than on any other off road car I've ever seen! This might provide more grip, but I believe it will bind the rear suspension, making it handle even worse on rough tracks :eh?: I think this is where Chris Long's idea is perhaps better as it would appear to offer a slightly better weight distribution, but also improved handling. I suppose the key question is what is everyone tring to achieve - more grip or better handling? I'd be interested to hear what others think about the driveshaft sweep, and in particular, how much is too much? I also agree with the suggestion that it's the volume of the shocks that need looking at, I personally think the kit shocks are crap :thumbdown: |
Me pesonally so far think the shorter wheelbase as per schumacher mod is the best (for me)! Not that it will suit all tracks though!
Chris's wau of doing gives pretty much the same result as just moving the shock to back, if your not confident of drilling a new hole for the shock then Chris option would be better, but TBH its fairly easy to do new hole, but it could go wrong lol! What i did originally a while ago if you do wish to shorten the wheel base is, on the wishbone there are 2 plastics bits either side, one about 2mm i have sanded this off to move wishbone forward then put a 2mm kwick klip in the back! |
I ran mine today (with other mods), and it felt really good. It felt better than my unmodified Cat by far, but I was struggling for power as I was running some lower power Lipo's than usual.... so I need to run it again with something with some bang in them.
The track today had some areas where traction was low, and the car squirmed on power, just like the std car did. But watching Nathan Waters and he clearly got the power down and made less of a deal about it. So I reckon the mod using the Schumacher option parts is the way to go. Then trim 2mm off the rear of the flipped wishbones to recover a little bit of length in the wheelbase - just like Pupton said. The driveshaft sweep will stiffen up the suspension on power, as the dogbone naturally wants to run straight at speed. So on acceleration it will stop the rear from squating, and drive the tyres into the ground creating some mechanical additional grip. At constant high speed, say on the straight, it will make the back end bob about. Could just balance this by softening the shocks..... but..... by putting the shocks on the back with the shift of weight etc, the shocks in theory should be a shade harder - so by not changing them atall we may be counter acting the driveshaft sweep effect... Trial and error...... thats how I work, just try to learn from it... :lol: (so I can ask you when I forget) |
I'm still not convinced by the mod. I ran mine as per kit standrad today at Blyth and finsihed 3rd and not that far of Nathan, I also did qualify as the highest placed CAT (in the Non-Regiona).
I honestly believe it comes down to driving style. I'm not that aggresive and fairly smooth, due to this I don't believe it will have an effect. I will of course be trying the mod but it will be the next time I have a 'free fun' meeting. |
Agree with Chris about runnin a touch harder. I ran 30wt on 3 holes in the rear at Oswestry, which is 5wt harder than i normally run. Movin the shocks out to the back will allow you to run stiffer oils due to shiftin the weight of the rear end.
Si |
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hey mark here are the pics ive alterd the shock tower mountings since wednesday i think you will agree this is better.
stu |
Looks sweet Stu! Iv done my one today, if I can figure out how to post pics I will! I have drilled arms and left wishbones and mounts as they are.The garden test seemed better, Wednesday will be the proof!
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This is how I did my rear shock mod: I used long M3 bolts and a damper tube from an AE L4 12th car drilled out to act as a spacer for the shock tower, shock mounts are std and a re drilled the arms. Since this photo I have fitted the Sch SWB kit.
http://img199.imageshack.us/img199/671/ebay005l.th.jpg[/url][/IMG] |
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Guys, both of you need to note, if there is not enough surface area between the tower and the mount (the spacing) then the screw will bend very easily. Being spaced back it'll have more leverage, so you need something to spread the load.
I have now fitted the Schumacher kit, and it feels great. I have gone with the short wheelbase rather than trimming the wishbones atall to get it back, and it feels really good... but it also felt really good the way I did it before, and before that - it still felt really good with shock on the front. LOL |
I ran mine with the Schum kit yesterday on a rather bumpy hard packed clay track.
I first tried the kit layout (front shocks), then shocks at the rear with drilled arms and finally the Schumacher kit. I felt little difference between the kit layout and the drilled arms rear shock mod. The rear shocks felt a little grippier but nothing major. As usual, the CAT drove like it always does on slippery or bumpy tracks as a really pronounced "front end car", with the rear drivetrain sometimes a little "lost" in the proces (if you know what i mean). Mounting the Schum kit and swapping the rear arms made one hell of a difference. Suddenly the rear end felt rock solid. It generated so much more grip, i had to change a lot on my setup to get enough front end bite to compensate. :D Is it better ? I don't think it's actullay much faster on a single lap, but it certainly makes the car a lot safer/easier to push hard on bumpy, slippery surfaces and that's always a good thing. |
im assuming you are talking about shotning the wheel base and mounting schu kit
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I think that is what I felt too at EPR, but I have also moved the weight far more rearward in my chassis.... and it feels soooooo much more pushable.
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By making my own Saddle Lipo chassis out of the Schumacher stiff chassis, and making a Brass Lipo retaining brace which hold the rear 1/3rd of the cells. My weight bias is now 57% to rear, it was 54% before.
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Would be interested to see some pics Chris
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Myself and Spud31 ran the Sch SWB kit last night indoors at Faversham (polished wood floor) , Rich seemed to like it but I found it very snappy and tail happy to drive, put it back to normal wheel base now.
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stu |
Just a little warning for those using the mod and using extra droop and 3°+ rear toe-in on the CAT : keep an eye on your driveshaft seating in the outdrives. I had mine pop out during our nationals last weekend.
Shimming the driveshafts proved enough to remedie the situation. |
To try and help you guys doing the mod, I found that with the suspention on the rear this gave the car alot more weight transfer, and with the long ball joints on the shocks this made the rear loose on entry into the corner and the front push out the corner, now having gone back to the short the ball joints this has stopped both these problems, hope this helps!
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Now that there are a few of us running the SX at my local low-grip dirt track, we are finally starting to improve the car for Aussie conditions. My car was handling and jumping very well, with the rear shock mod fitted for the first time.
However, I'm still not convinced that its effect is that great, and I believe that the mods greatest grip improvement comes from the sweep of the drive shafts, rather than the ballast difference by having the shocks out the back. I've done a few calculations and discovered that moving the shocks to the back is only moving around 2.5% of the mass back approx 6.7% and moves the wing back only 3.2%. How much this contributes to improving grip is debatable, especially as my own car was never really lacking in grip to start with. The biggest improvement in my car has been the fitting of Tamiya shocks from the 501x, which certainly improved the cars handling over the bumps. Next meeting I will be trying something else, running the shocks at the front of the arm again, but modifying the arms so that the wheelbase is reduced a further 2-3mm from the kit "short" position. This should result in a similar wheelbase and driveshaft sweep compared to reversing the arms, but still allows the shocks to be in their original locations. The next step is to try and get the motor as far back as possible. I'm switching to the 80t spur for the next meeting but it would be better if Schumacher made down to a 75t spur I think, though perhaps it would be difficult to get the right ratios with some of the hotter mod motors. |
Im using a 78tooth Losi spur on mine - for motor position. Any smaller and I can't mesh the pinion.
Im on 78/23 on a 5.5 Speed Passion. I am using the car as standard, I felt the driveshaft angle locked the shocks on power not allowing them to absorb bumps - felt very skitty to me... I tried several ways of doing it, and it was at no point better than the std mounting position. |
Chris - Any mods to fit a on a Losi Spur Gear ?
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Also is that a Tekin RS Pro in the car? |
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I probably should've checked a bit more thoroughly before buying the gear :blush: |
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Ideally, we need layshafts turned down to suit the spur - know anybody with a lathe? Chris |
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stu rand |
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As Mike Williams says, Dave Orbell (son of Mr O Foams) turned some down for a few of us and I still have a spare in my glove box! Not sure of size but I think Dave has done enough to do it from memory!
I am still using the original Schumacher spur gear that I got with the car without issue but have the option of using AE/TL spurs if necessary... |
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