XRAY - Model racing cars

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 Post subject: Rear diff Pinion Bearing wear.
PostPosted: Sat Aug 10, 2019 12:18:03 

Joined: Sat Aug 10, 2019 12:15:45
Posts: 1
Hello everyone,,
I have been racing my 808 now for a few months but am struggling to keep bearings in the rear pinion. i dont know if it is crashing causing the rear driveshaft to try to push out or something else.

After 3 x 10 min heats and one 30 min final the pinion is slopping around in the diff case.
I bought the new V2 diff cases last week and fitted them with new Avid bearings. I run the alloy centre spacer between the bearings, but i have noticed it is not the same thickness as the pinion. (Fit the spacer and the pinion can still move fore and aft on the bearings meaning the spacers is too thick)

When i screw the 3 bearing retaining bolts down in the diff case the pinion and bearing assembly can still move in and out of the case and i think this is where the problem is coming from as it is not properly supported. The 2 x bearings and one x spacer ring height is less than the height from the screw face to front bearing face.

My solution is to accurately measure the depth of the V2 diff case and machine up a new bearing spacer that is exactly the same size as the step on the pinion. then i am going to machine a spacer up to fit in front of the front bearing that packs the two bearings out so the 3 screws solidly hold the bearing assembly in place.

I believe getting rid of all the clearance will fix the problem i currently have. At the end of a race meeting i struggle to turn the wheels over by hand as the pinion is sliding in and out of position and not meshing with the main gear anywhere near properly.

Front pinion lasts longer, but has similar issues,

Are there any thoughts from the gurus or people who have been racing the car longer than i have???

Cheers and thanks.

Last edited by Helsinki on Wed Aug 14, 2019 20:07:38, edited 1 time in total.

 Post subject: Re: Rear diff Pinion Bearing wear.
PostPosted: Tue Aug 13, 2019 22:55:10 

Joined: Fri Mar 09, 2012 06:55:56
Posts: 6
Hi, is this a legitimate question?
This forum has been dead for a while, and the 808 is ancient now hence my asking this.

If yes, then the answer is definitely to ditch the entire old setup and switch to the 808 '11+ design where they went back to traditional 8x16x5mm (x2) diff pinion bearings. Xray made a mistake on this buggy here, and thankfully they recognized it from 2011+, and for the last entire decade has probably had the best drivetrains in the business. I hope they continue to use the 8x16 instead of switching to smaller bearings like other manufacturers.

I had to deal with the same mess in the past myself, and this was my solution which lasted a very long time.
You can use XT8 or XT9 10T pinions from any year model including current 2017-2019, they are compatible with your 43T 808 ring gears.

For the center shafts you can use any XB8 center CVD from 2011 to 2019, ideally choose newer ones (XB9 '13 through to current).
You can't use the 808 ones any more as they are too long, but ditching that entire inferior design is worth it.

The parts compatibility on these vehicles is amazing, diff casings still use the same pattern which I really appreciate.
If you don't mind spending the money again, I recommend just replacing the casings instead of doing what I did in the above thread, I eventually replaced them.
The design of having the bearing seat in the middle of the two bearings is just superior. The original design as I said was just a mistake, all the recommendations / spacers / tech tips just delay failures, the real solution is to switch to the updated design. Good news is once you do that, it will last for many years.

Best wishes,

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