Zehner189

Can't figure out how to fix this. I have an XTM Rail. Have it set up pretty well. Swapped out the stock shocks for some big bores. Well after the swap I went for a test run and now when the car goes off a jump the rear end comes up hard even under throttle. I was thinking the springs were too soft, but after comparing them to the stock ones they feel about the same. If I loosen up the ring then it goes away but then the rear end drags off the jump. It never did this with the stock shocks. I'd rather run the big bores since they should be able to hand the big jumps and what not. Any ideas on how to fix this?

bloodpuppy

How is the weight, front/back?
And ive heard softer spring in the back then the front.

redlined_b16a

Sounds like your shocks are too stiff or maybe your oil is too thick,check for air in the oil
is it just a certain jump or all of the jumps
have you tried applying slight brake while in the air?

Zehner189

It's all jumps.  I'm running 15mm big bores, with 1.2mm pistons, and 1.5mm springs with 35wt shock oil from XTM.  If I do slight brake the car just front flips.  I'm wondering if the new mamba I put in it is throwing the weight of the car off.  It does weigh more than the I did notice that the stock shocks were running 40wt, and 1.6mm springs.  I never had an issue till I swtiched to the big bores.  I'm considering buying OFNA's big bores cause XTM has discontiued their big bore shocks and springs. 

redlined_b16a

sounds to me like the shocks just need fine tunning until You get it right
so besides that how does the rail stack up?

Zehner189

Love the Rail.  It's super strong.  Great basher!  I'll try and get some videos up soon.  I've been fine tuning it for a while.  It's hardly stock anymore.  Mamba motor and esc, redid the whole roll cage, and added aluminum plates to the front half for deflection, front and rear mud flaps. Since the rail has open sides a lot of dirt and debris get in the chassis so the front flaps are more like deflectors.  Swapped out the entire front end for what is on the XT2.  It's a lot stronger, and holds up to landings so much better.  Did a few other fine tunings just because I found design flaws. 

All in all the car is awesome.  I know how to fabricate a lot of stuff, so I've made shields, and stuff for certain parts. Just been watching how things break, and redesigning accordingly.  But the platform is solid. 

I had a brushless erevo before this one, and that thing sucks compared to the rail.  I can regear my rail and out run a revo easily!  Especially since I have the mamba on it now.  I'm working on a second Rail.  My guy in Cali cut me a great deal.  So I'm going to basically build a second one.  Since I have one already I won't run the second one till I get it perfect.  I have a few ideas for the second one but that will be a secret till I get it all worked out (pics and vids to come)

I know XTM isn't Kyosho or OFNA, but I think people should take a second look at them.  Parts are actually pretty easy to come by.  Plus they did a great job mixing parts on some of their cars/trucks.  Makes a huge surplus on parts. 

I'm considering racing it soon.  Once I get a couple more kinks worked out. 

tommygun32

I'm sure you already know this.....however.....

As your car heads into the face of a jump, your suspension compresses due to the forward momentum, versus the angle of jump, versus speed, versus inertia, versus gravity......

So....as your car travels up the slope of the jump....(depening on angle and distance)....your car's suspension will most likely be compressed. Especially towards the back end.

Now...as soon as the car begins to clear the top edge of the jump.....it begins to 'unload'. How quickly that happens depends on your suspension setup. re, shock oil viscosity, spring strength, dampers, pre-load setting, etc.

If it happens too quickly....you will most likely flip the car over onto its shell....especially if you hit the brakes while it's in the air.

I would recommend a lower viscosity oil and a softer spring with enough pre-dampining just to make the car's suspension sit at 90 degrees from center....i.e. drop the car from a foot up and if the chasis rests at a right angle to the a-arms....you should be sorted...

Just myovver analyzed and tipsy opinion

Good luck and let us know what happens.

littlebuddha

My Feedback: (17)

Hey guys, trying to get a definitive forum for new owners and potential owners so that we can help each other with the rail -i.e mods, getting parts and interchanging parts between other xtm trucks. Most forums have not been updated in a while and I had problems finding good info - hopefully we can change that.

http://www.rctech.net/forum/electric...-thread-3.html

If you guys are interested please head over here and provide input on the buggy. Sorry if its not rcu - but rctech community is pretty fantastic! thanks.