New XRAY 808

Old 08-19-2010, 03:06 PM
  #7756  
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Originally Posted by bigmatt
for some reason I cannot understand all the bearing problems. I still feel it is an issue with chassis flex. I use a kingsheadz engine mount with the extended arm. I am on my second set of pinion bearings since april.
I think your on the right track there Matt. The latest buggies (say over the last 2 years) all have a tremendous amount of chassis flex when compared to older models. I have slightly bent a couple of rear drive shafts on my 808 going over big jumps and landing a little harshly (and thatīs being kind to my driving skills ). The chassis must be flexing a hell of a lot to take up the slack in the rear centre outdrive and then carry on far enough to put a bend in the drive shaft.
I believe most of the trouble the new Serpent buggy is having with throttle servo failure may be coming from chassis flex too. Becasue the throttle is pushed open on this model (as opposed to pulled open), when the chassis flexes at WOT the motor is being pushed back towards the servo arm. The throttle slide is pushed to itīs limit, and all the force that is causing the chassis to bend is then transmsitted back through the thottle linkage to the servo itself. In a normal set up, the throttle just gets pulled closed against the return spring with minimal pressure on the servo.
Maybe manufacturers need to stiffen their rides up a bit and find other ways to improve stability and handling ? Is that possible ?
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Old 08-19-2010, 03:48 PM
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I still run my 808 08 and it come from the first batch to hit the states.I dont get to race alot so it only has about 3 gallons on it but i have never had a bearing go out on it.I just back the 3 screws out 1/4 a turn and pack alot of grease in and around the bearings and the bulkheads and replace the bearings when they get notchy.I did change over to the 09 setup but never had a problem with the 08 setup.knock on wood lol!!
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Old 08-19-2010, 03:52 PM
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Don't know Grizz. A little flex is good,but strapping a 2+ horse power engine onto a 7 lb buggy something needs to give. When I first got my 808 I thought of using a chassis stiffener from a jammin x2 truggy. Then saw the kingheadz engine mount. I had the same problem with my jammin x-2. The chassis flexed so hard after big jumps/hard landings I was bending the center cvd's, and jamming the drive cups into the cases. Put on the jammin extended arm engine mount problem went away. I also used the kingheadz chassis braces as I snapped 2 of the rear factory ones [for my jammin x-2]
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Old 08-19-2010, 07:45 PM
  #7759  
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One thing I noticed is that the chassis cutout holes for the diff spur gear and the engine flywheel are very close by, the rigidity of the chassis can be pretty weak at that spot... The closest point between the two cutouts is merely 12mm! If you measure the chassis again, the width of the chassis at the particular spot is approx. 110mm and the two cutouts combined width is about 65mm, that's almost 60%. Effectively (with my oversimplified analysis) we are left with approx 40% of the 110mm total width to take all the working stress!

Using an extended motor mount might stiffen up the chassis a bit at that particular spot...
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Old 08-19-2010, 08:07 PM
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Originally Posted by ganymede
One thing I noticed is that the chassis cutout holes for the diff spur gear and the engine flywheel are very close by, the rigidity of the chassis can be pretty weak at that spot... The closest point between the two cutouts is merely 12mm! If you measure the chassis again, the width of the chassis at the particular spot is approx. 110mm and the two cutouts combined width is about 65mm, that's almost 60%. Effectively (with my oversimplified analysis) we are left with approx 40% of the 110mm total width to take all the working stress!

Using an extended motor mount might stiffen up the chassis a bit at that particular spot...
what he said!!!! LOL I practice in a fckin dust bowl basically. Need to change air filter every 2-3 tanks. I use to take apart every week just cuz of the problem. But now I use my cleaner,blow off buggy with air compressor and respray into the bearings with kal-gard 30-30[all bearings/and where ever else it will go] then take a paint brush ,brush off excess. But I do feel because of that weak point like you have stated could cause undo binding in the bearing pinion section. Just my opinion.
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Old 08-19-2010, 08:08 PM
  #7761  
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Originally Posted by ganymede
One thing I noticed is that the chassis cutout holes for the diff spur gear and the engine flywheel are very close by, the rigidity of the chassis can be pretty weak at that spot... The closest point between the two cutouts is merely 12mm! If you measure the chassis again, the width of the chassis at the particular spot is approx. 110mm and the two cutouts combined width is about 65mm, that's almost 60%. Effectively (with my oversimplified analysis) we are left with approx 40% of the 110mm total width to take all the working stress!

Using an extended motor mount might stiffen up the chassis a bit at that particular spot...
The problem isn't with the stiffness of the chassis, but with the enclosed diff case. When the chassis flexes, the pinion pushes and pulls on the bearing. Since the bearings are "trapped" in the diff case, they have no where to go and eventually blow up. It would be nice to go back to the XB8 bulkheads...

I just don't like to sacrifice traction

I have found that by putting a 14x20 shim inside the diff case and over top of the bearing, it doesn't allow the inner race to be pushed out and it seems to help the bearings last longer. Since doing this, I haven't had any problems
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Old 08-19-2010, 08:14 PM
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Originally Posted by CJ Weaver
The problem isn't with the stiffness of the chassis, but with the enclosed diff case. When the chassis flexes, the pinion pushes and pulls on the bearing. Since the bearings are "trapped" in the diff case, they have no where to go and eventually blow up. It would be nice to go back to the XB8 bulkheads...

I just don't like to sacrifice traction

I have found that by putting a 14x20 shim inside the diff case and over top of the bearing, it doesn't allow the inner race to be pushed out and it seems to help the bearings last longer. Since doing this, I haven't had any problems
got a part# for the 14x20 shim you mentioned?
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Old 08-19-2010, 08:23 PM
  #7763  
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Originally Posted by bigmatt
got a part# for the 14x20 shim you mentioned?
Haha, to be honest is was one of those things that I had laying around in the spare parts box. I have been looking into, and I have a feeling it is an O'Donnell diff shim, but as soon as I find out I will let you know.

The thickness is .12, If you start going much thicker the gear mesh might start to get messed up. I have gone up to as thick as a .15 but that is it. Again, the thickness isn't really important, as long something covers the entire bearing.
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Old 08-19-2010, 08:24 PM
  #7764  
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Originally Posted by CJ Weaver
The problem isn't with the stiffness of the chassis, but with the enclosed diff case. When the chassis flexes, the pinion pushes and pulls on the bearing. Since the bearings are "trapped" in the diff case, they have no where to go and eventually blow up. It would be nice to go back to the XB8 bulkheads...

I just don't like to sacrifice traction

I have found that by putting a 14x20 shim inside the diff case and over top of the bearing, it doesn't allow the inner race to be pushed out and it seems to help the bearings last longer. Since doing this, I haven't had any problems
my logic is: cutouts -> reduced rigidity -> causes excessive flex -> drive shaft punching the pinion bearings -> bearing failures...
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Old 08-19-2010, 08:27 PM
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Originally Posted by bigmatt
got a part# for the 14x20 shim you mentioned?
this should work:

http://www.amainhobbies.com/product_...ntial-Shim-Set
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Old 08-19-2010, 08:32 PM
  #7766  
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Originally Posted by ganymede
my logic is: cutouts -> reduced rigidity -> causes excessive flex -> drive shaft punching the pinion bearings -> bearing failures...
I definitely understand that, but the Xray doesn't seem to flex THAT much more than any other vehicle. If the Xray chassis was that flexible then I could understand the bearing problems being caused by the chassis but it just seems like any flex at all will put stress on the bearings.

I don't know who the distributor is for Raptor helicopters, but here is something very similar to what I am using that should work:

http://www.ronlund.com/Merchant2/mer...t_Code=SHIM141
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Old 08-19-2010, 08:33 PM
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Originally Posted by ganymede
my logic is: cutouts -> reduced rigidity -> causes excessive flex -> drive shaft punching the pinion bearings -> bearing failures...
I'm leaning to that train of thought,which is working for me. But I am always willing to here others theories. I've ran almost another gallon through the car since I took diff's apart. after this week ends running I am going to take apart and see what's up in there.
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Old 08-19-2010, 08:51 PM
  #7768  
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Originally Posted by CJ Weaver
I definitely understand that, but the Xray doesn't seem to flex THAT much more than any other vehicle. If the Xray chassis was that flexible then I could understand the bearing problems being caused by the chassis but it just seems like any flex at all will put stress on the bearings.

I don't know who the distributor is for Raptor helicopters, but here is something very similar to what I am using that should work:

http://www.ronlund.com/Merchant2/mer...t_Code=SHIM141
Other cars like the mbx6 and mp9 uses the tried and trued "pinion gear + grub screw + cvd coupler" system... all chassis designs will flex but if u look at mugen or kyosho or even the old XB8 drive train u will notice that the cvd coupler (outside of the bulkheads) design actually limits the travel of the drive shaft (punching) in and out of the bulkhead...

In the mugen/kyosho design, any excessive punching force or travel will be stop right away by the cvd coupler slamming on the plastic bulkhead, the stress path is much short and more efficient to dissipate the forces...

Whereas in the 808, the travel is only limited/restricted by the small inner race of the pinion bearing (esp. the inner bearing)... The inner bearing race can only transmit so much force to the ball bearing -> outer race -> 3 small screw -> bulkhead...
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Old 08-19-2010, 11:38 PM
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Here's some pictures to illustrate what I meant:





The CVD coupler effectively limited the travel of the drive shaft, lessen the stresses on the pinion bearings when the chassis flexes...

Pictures courtesy of Mader of XRAY Forum, details of the mod can be found here:

http://forum.teamxray.com/viewtopic....10630&start=40
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Old 08-22-2010, 04:10 PM
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Default V2 Clutch Bells

I'm having trouble finding part numbers for the V2 clutch bells. Are they just the clutch bells with over-sized bearings? Looking at A Main Hobbies, there's nothing noting which bells are V2. I'm wanting to use the labyrinth covers.

Last edited by KyLayfield; 08-22-2010 at 05:24 PM. Reason: Spelling
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