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Old 03-30-2009, 08:16 PM   #1
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Default JRXS Type-R Tweaked Chassis????????

Hey guys, I'm pretty green at all this RC Car stuff and I've started running at our LHS track in the VTA series.
I'm currently running a Losi JRXS type-r with 21.5 Brushless/Lipo. This past weekend they were running a VTA Oval race and I was having all kinds of problems setting my car up. A fellow racer decided to give me a hand and check out my car. He helped me adjust the TWEAK and balance the car a bit. But after setting ride height to 5.5mm We both noticed that the left side shock spring collars were cranked down quite a bit farther than the right side collars. We looked over EVERYTHING on the car. Droop is ok, roll center is correct. Diff height is good, The chassis appears to be straight, and the suspension is not binding anywhere, but why the difference in the shock collars?? Should this be something to worry about?? Otherwise the cars tweak is A OK and everything else on the car is setup properly now. I just dont like the idea of the shock collars being that far off just to keep the ride height correct.

Any ideas????????


Thanks in advance for the help.
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Old 03-30-2009, 08:33 PM   #2
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Quote:
Originally Posted by jcboof View Post
Hey guys, I'm pretty green at all this RC Car stuff and I've started running at our LHS track in the VTA series.
I'm currently running a Losi JRXS type-r with 21.5 Brushless/Lipo. This past weekend they were running a VTA Oval race and I was having all kinds of problems setting my car up. A fellow racer decided to give me a hand and check out my car. He helped me adjust the TWEAK and balance the car a bit. But after setting ride height to 5.5mm We both noticed that the left side shock spring collars were cranked down quite a bit farther than the right side collars. We looked over EVERYTHING on the car. Droop is ok, roll center is correct. Diff height is good, The chassis appears to be straight, and the suspension is not binding anywhere, but why the difference in the shock collars?? Should this be something to worry about?? Otherwise the cars tweak is A OK and everything else on the car is setup properly now. I just dont like the idea of the shock collars being that far off just to keep the ride height correct.

Any ideas????????



Thanks in advance for the help.

I run an Xray T2008 and i too had a chassis tweaked. One shock collar was lower than the other. There are a few things that can be wrong.
1. Your weight balance is off. solution- rebalance it
2. Chassis is twisted due to top deck. solution-loosen top deck, get someone to push chassis flat on setup board while you tighten the screws.
3. If none of these help, I would suggest getting a new chassis.
One way to see if you have a twisted chassis is to check the ride height at the sides of the chassis when you have the front and rear ride height set. That is how i found mine.
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Old 03-30-2009, 08:44 PM   #3
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Take the standoffs off (what the battery tray screws into) and set them against a flat surface and check to see if they are bent. I've had this issue before and it was mighty frusterating, all it was was a slightly bent standoff. I got through a set a season because they are so dang flimsy (you can bend them back by hand if needed).

Hope i helped!

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Old 03-30-2009, 09:41 PM   #4
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Different length springs?
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Old 03-30-2009, 09:46 PM   #5
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jcboof, are yu saying both front and rear left collars are down more than the right? If so sounds like a balance problem. Try to post a pic of your car.
Are you sure you don't have your springs mixed up? Or maybe your droop screws are too far in on the left side.
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Old 03-31-2009, 02:43 AM   #6
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Slighly different a-arm sweep will also cause this, either by incorect assembly or slight tolerance issue in manufacture of the parts on the car.

It also could be when the screws/studs on the a-arm where first put in they might be going in slighly crooked ( the ones that the bottom of the shock goes onto.

Or it could be the other things the other guys have mentioned, the posiblities are truely endless.

Last edited by LOSI123; 03-31-2009 at 06:06 PM.
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Old 03-31-2009, 05:06 AM   #7
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I'll have to look into all those things tonight. I never thought about the standoffs being tweaked. My car did take quite a beating the other day running oval. I got spun in mid apex and ended up on my top and then 7 other cars piled into me!!! It was pretty darn rough.

I'll look into everything that I can. Maybe there is something I'm overlooking.
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Old 03-31-2009, 07:47 AM   #8
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Heh, Welcome to Onroad let the headache begin!

suprised this wasn't mentioned, make sure your front and rear shock's are the same length, you can use digiital calipers. Take the shocks off and make sure that your arms move freely, should move up and down with 0 resistance. When you check you topdeck you need to loosed screws on the top and bottom to "reset" it. If you are running foams, you need a digital caliper and check the tire wear(make sure they are not very far off)

and that's just the easy ones, you can check your battery packs too, make sure no bars are bent and making them tweaked( should all lay perfectly flat on a flat surface) Like I said just a few, let us know if any of these help.

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Old 03-31-2009, 04:27 PM   #9
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i'm really hoping its nothing serious!
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Old 03-31-2009, 04:36 PM   #10
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Hey dude,
Release the top deck, try to notice if the car relaxes when you loosen the screws one at a time. Shock length is the next obvious thing to check. Use your calipers to check the wire diameter on your springs. Most of my springs are now missing the little stickers. It's real easy to miss one.

If you come to the track Friday I'll take a look at it. I know your electronics aren't off that much. Your car looks almost exactly like mine, we'll figure something out.

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Old 03-31-2009, 05:02 PM   #11
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Sounds good, Thanks Ben!! Me and Seth were trying to figure it out on saturday during Oval racing but just got things good enough to run decent. I'm sure its probably something we can figure out. I'm Positive the springs are ok. I initially noticed the problem after switching from a Low to High roll center on the front end. Maybe that has something to do with it. I readjusted droop and everything but who knows, I'll try that top deck trick and see how it goes. I'm almost sure it has something to do with that because of how hard it got hit. Someone hit me hard enough to take a chunk off the corner in the rear of my chassis!

Thanks!
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Old 03-31-2009, 06:12 PM   #12
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On shock length:

If you have shocks built with no rebound in the oil/foam and all 4 of the shocks are asembled using the correct parts (ie: the plastic thing on the end of the shaft that holds the spring holder in place), then theroeticlly it wont matter if your shock is "slightly" different length than other side (from say the platic end thing not threaded on quite as far as the other one, as when its on the car and at rest, well it just means the shock piston will be that .5mm or so in the oil more than the other side which meens jack all if you have no rebound.

But if shocks are built with rebound then i can see how it would matter (shock length exact)
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Old 03-31-2009, 06:44 PM   #13
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I have the shocks built with a little bit of rebound in them right now, I'm gonna drain em and rebuild em again tonight though with even less rebound. The problem I was having was a tricky one but I found it!!!
Last weekend when racing, I was slammed into the wall and broke a C Hub. The new one I put on had a slight burr on the edge that goes into the lower arm, It was slightly binding and causing the left front to be all out of whack! After trimming the burr and reassembling things including loosening the top deck, The shocks all sit the same now. I set my ride height and afterwards put the car on my tweak gauge and I had to make 1 TINY adjustment and the car was balanced! The shock collars are now all in the same general area!

Thanks for all the great advice guys, Its just easier to ask people for help then try to find answers on your own sometimes!!


Now, Off to rebuilding my diffs AGAIN!! Used too much lube last time and they are a little stiff!
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