XRAY - Model racing cars
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Final solution for the 808 diff bearing problem
http://forum.teamxray.com/viewtopic.php?f=9&t=10731
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Author:  razo125 [ Fri Oct 22, 2010 18:57:54 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

guy02 wrote:
I don't want to....
I want bearings, that don't need looking after for at least 4 months
and I don't need smaller bearings to gain 1-2.5 grs
not to speak of the costs with the xray parts, those being not the cheapest

I had those issues before (1 or 2 race days and bearing failure), but they are gone now. I got really upset about that when it failed. That was a costly repair. :roll: But today, I don't think everyone is having these issues, people try to help, but you seem close minded to listen. I don't care how man years experience someone has, people can always be open to learn more. I've got 26yrs exp racing and work in R&D in equipment reliability in another industry and I'm still always open to learn more. I'm not here to change your mind, and I don't expect to. My experience with the problem was different from yours. I just want to leave my experience for others to decide.
guy02 wrote:
I wonder sometimes, if the drivers that don't have problems
have jumps on their thracks or not, or drive very carrefully
should make a difference with the chassis flexing a lot more

also the use of the 41T gear up front, the front can pull on the teeths of the rear gearing

I'm not a pro driver but I'm not a novice either. I guess I would represent a majority of xray customers. I'm an intermediate club racer who sometimes goes to nearby big events. So I've had my share of occasional lawn darts.

I race on extremely rough tracks, tracks with HUGE HUGE motocross type jumps and I've had no issues during the course of running those bearing up to 2 gallons. (The Nitropit, Fear Farm AZ, Sun Lakes, ET motorpark, SRS, Thunder Alley)

I got two gallons on my bearings before I swapped them out as a precaution. (I run the 2 bearing setup) They definitely lasted longer than the 1 or 2 races that I read about on these forums. I just follow Xray's recommendations. I don't however check them every race day, or regrease them every race day. I just pack them with grease LOTS of grease. Shim properly. (I also recently added the rubber outer shield and have 1/2 a gallon on that setup) Maybe I've just been lucky.

Although chassis flex might contribute to more failure. I'm not sure this is the main reason for failure. The things that fixed this issue for me are extreme attention to detail on proper shimming, and and LOTS of grease.

Author:  Jaap3 [ Wed Oct 27, 2010 23:09:44 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

Jaap3 wrote:
carld wrote:
Jaap3 wrote:
When I was at the track I could hear a squicking sound while driving as if something was jammed. The difference from other times was that this time I used the diff tech tip provided by xray and greased the bearings. I went home looked at both front and rear diffs and both looked fine with all their bearings. Also checked the bearings of the hubs but all ok as well. Could that sound be coming from the tech tip since now there is grease in the diffs which might cause the middle metal ring between the bearings to make that sound?

Also I see there is alot of drag due to the grease....will this not affect the engine? Shorten its lifespan maybe?

Thanks


The four CVDs that connect the difs with the wheels? Should I grease them up?

Yes as it will allow things to turn without friction when under load, it will also last longer before its worn out.


I did what you said but not difference...I think it is due to the diff tech tip where I added alot of grease between the two pinion bearings and the metal o ring in between them (2010 spec)....I don't know what else to check. Nothing wrong with the bearings...I can listen to it only when the car is moving with the engine running. Nothing wrong with the engine/clutch bearings

Author:  Bren Ralls [ Thu Oct 28, 2010 20:36:25 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

The grease tip will add a little friction due to the grease but this goes after running for a short while. Any squeeking can be many things breaks binding incorrect gear mesh on diffs, mesh on clutch & spur, Shimming to tight on engine to do with clutch so when it gets hot can expand & bind. Whishbone pins or anti roll bars all squeek after a time if run in dusty conditions. As you can see many reasons just a process of elimination.

Author:  Mader [ Fri Oct 29, 2010 03:36:38 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

Razo Im glad to hear you are able to make your car last as long as you say but switching your driveline to either one of my or extra's designs will eliminate all of the drag that Im 100% sure your car has. After just one race you could spin the wheels on my car and they would go around 3 to 4 times before stopping. Now its even smoother. Im willing to bet yours won't turn over one time. Too much drag and too much grease.

Author:  Zerodefect [ Thu Nov 04, 2010 22:46:28 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

Mader wrote:
One of the other contributing factors to the outer bearing failure is the fact that even with the spacer installed between the stock bearing setup you can still move the pinion gear in and out which I hated. If you have wheel spin upon landing the pinion gear tries to shoot itself out of the case but stops as soon as it slams into the inner race of the outer bearing. Most of us USA guy's used to race motocross and have alot of the same driving tendencies in rc racing Myself included. That being said I only missed one A this season so I must be doing something right.

Bren Im glad to hear you guy's are doing some testing of your own and I hope all of the input be it positive or negative will help better the car overall. Im sure regardless of what the new chassis will be I have a bulletproof car for 2011! :lol:


You need to shim the pinion. You can shim the pinion in or out depending on where you put the shim. It's the same shim as the shims used to set the diff left or right. Put the shim between the bearing and the bulkhead to move the pinion assembly in or out. You should not have too much play.

You may need new pinion gears.

My car needs the diff shimmed 1 shim closer to the pinion, and one shim on the pinion. If I remember right, I shimmed the pinion out, not in.

I have been able to get my car bulletproof with the stock diffs. It takes some practice to get it right. I change my pinion bearings and diff fluid every three race weekends. I've never had any problems with the rear bearings, only the front pinion bearings and I believe I have that problem solved. The factory Xray bearings are best for the front pinion, I use Avid revolutions everywhere else.

I have not been able to get the 41th ring gear to shim well. Seems gritty, and I didn't like the way it steered once I fixed other areas of my setup. But with 43t gears I'm golden. If your car picks up a ton of steering in the middle of a race, or alot of turn in, pull it off the track quick. Before your engine cooks, or if electric, your battery bursts into flames. The front end drag of a bad bearing/pinion/ring is alot of load. I lost a 4s 4500mah battery that way.

ps: where in Ohio r u? I'm in NE Ohio.

Author:  Mader [ Sat Nov 06, 2010 05:06:01 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

Zero I ditched the stock driveline and upgraded to the new bulletproof Mader design which is really just other Xray parts and a custom sleeve. Im in Urbana Oh where we are putting the best track is Ohio in right now. Go check it out at www.area54rc.com

Author:  guy02 [ Sat Nov 06, 2010 16:04:59 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

can someone explain, what is the advantage of the 808 driveshaft system ?
or why xray wants to use it ?
I don't see any...

Author:  Mader [ Sun Nov 07, 2010 01:17:03 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

The benifit is that the driveshaft pin is captured when the bearing is installed for reliability. Also more room is gained in the center of the chassis and theres less spinning mass because theres no heavy coupler on the pinion gear. It also results in less parts. I really like the design but it failed the durability test time and time again because of the bearing issues.

Author:  razo125 [ Sun Nov 07, 2010 16:42:00 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

Mader wrote:
Razo Im glad to hear you are able to make your car last as long as you say but switching your driveline to either one of my or extra's designs will eliminate all of the drag that Im 100% sure your car has. After just one race you could spin the wheels on my car and they would go around 3 to 4 times before stopping. Now its even smoother. Im willing to bet yours won't turn over one time. Too much drag and too much grease.


Hi Mader, You do have a good point and that grease does get into the bearings. When I say use lots of grease, I mean mainly for the outside of the bearings. The grease takes up the gap between the bearings and acts as a dust barrier. My driveline is free, but anything can be improved.

I just put a normal amount of grease inside the bearings, and use a crap load on the outside to act as a shield. If you put too much grease inside the bearings, it eventually just flies out after a couple rips on the throttle. But Xray is the only company that says to use grease. And grease is not as free as just a oil.

One interesting thing I found is this interesting link that calculates a bearings maximum RPM. It makes me consider using ceramic bearings instead of the normal steels bearings.

http://www.phymet.com/calc.htm

Just plug in some numbers for Xray size bearings and the regular size bearings other companies use. A few light bulbs went off in my head after I did that. With a 43/15 spur/clutch gear ratio, what RPM range does the center drive line work in... I'll leave it at that so others can discuss what they find.

Author:  guy02 [ Sun Nov 07, 2010 18:44:08 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

in reverse, the pinion wobbles a lot more onto the conical gear
bearings are weaker
a costly gear crash can occur at any minut
it's a hazzle to remove the driveshafts each time, between the engine blocks
and the radiobox

less parts ?? :
2-3 bearings, a spacer, a pinion part, a driveshaft, a joint, 4 screws, grease..
with an xb8 homokinetic driveshaft, you have to unscrew, but one setscrew of driveshaft and pinion

Author:  Mader [ Sun Nov 07, 2010 21:01:05 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

Guy your preachin to the choir. Sounds like you need to upgrade to my system. Let Me know when you want some sleeves.

Author:  guy02 [ Sun Nov 07, 2010 23:44:02 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

thanks but actually
I have a xb tq fitted with the rear
and soon front suspension of the 808
8)

Author:  Mader [ Wed Nov 10, 2010 03:07:17 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

Sounds like a good combo. Post some pics when its done.

Author:  Jaap3 [ Mon Nov 15, 2010 12:15:05 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

Which one of these are the rear and front axels we are looking for this mod?

http://www.amainhobbies.com/product_inf ... wing-Shaft

http://www.amainhobbies.com/product_inf ... ng-Shaft-2

http://www.amainhobbies.com/product_inf ... wing-Shaft

http://www.amainhobbies.com/product_inf ... wing-Shaft

Thanks

Author:  extra [ Mon Nov 15, 2010 20:49:15 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

this one

KYOIF458 Kyosho Rear Universal Swing Shaft
and this one

KYOIF457 Kyosho Front Universal Swing Shaft

Author:  Mader [ Tue Nov 16, 2010 01:57:20 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

Yup those are the ones.

Author:  guy02 [ Tue Nov 30, 2010 22:07:45 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

also xray sends the wrong inputs to other manufacturers too
like Serpent and also the new OCM, who designed the same driveshaft system
and who's drivers will face the same problems

very disappointed in xray there....

Author:  mcgreaves [ Fri Jan 07, 2011 02:25:17 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

I just had the rear central drive shaft bend on my 808e. It partially collapsed the rear diff pinion bearing in the process. Everything was running fine afterwards, I picked up the issues during my regular rebuild

Author:  customworksking [ Sat Jan 08, 2011 05:13:45 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

i hope the 2011 808 does the trick.. sucks we will need to buy new bulk heads,shafts,pinions,bearings etc..

Author:  Marcio Sousa [ Sun Jan 09, 2011 00:29:07 ]
Post subject:  Re: Final solution for the 808 diff bearing problem

And a chassis plate :oops:

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