diff explosion!!!! (not really)

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randysavagex

randysavagex

Member
Messages
41
Location
COLUMBUS GA
K heres the deal I was on the track today practicing and soon i started hearing a grinding noise stopped the truck cut it off and took out the rear diff. Heres what I found both bearings were obliterated literally torn apart anyone have any idea what caused this it also melted the plastic on the dif case (its plastic).
 
I'm lucky to get a gallon out of my diff bearings. I have 3 Savages, so this gets annoying after a while.. I bought 6 spare bulkheads off of ebay since they get messed up when the diff beargings fail. I just recently bought BOCA grean seal bearings for my diffs. Hopefully they will last longer (if the price is an indicator....).
 
also forgot to mention that everytime i wash my truck i lube every bearing and every dif cup. I know its tedious but I like my truck clean! after a race
 
wow thats terrible I've been running the truck for a while with no prob and then bang. Do you have a link for the upscale bearings I'd appreciate it.
 
just had one do a simliliar thing

I found the bearing was rusty causeing the failure
 
frddyj said:
jud & i just got these bearings too. seem pretty good, but they'll get put through the paces starting in a couple weeks http://www.avidrc.com/
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After the original bearings (10x16x5) failed I installed bearings from avidrc.com. I figured they were a good price, so I'd try them. Well they didn't last any longer than the stock HPI.

Now I'm running BOCA green seal. So far so good (except for the dent in the wallet)....
 
Bocas are prob the best period. For half the cost Acer bearings is another way to go. Look at the ceramics. Another option.
 
Any bearing will fail if it gets contaminated in any way or if it runs dry. The quality and type of seal is the key. Unfortunately the diff bearings are probably exposed to more contaminents than any other bearing on the truck. They are also difficult to access for proper cleaning. Bad cleaning practices, such as blasting compressed air directly at a bearing can also cause premeture failure. The compressed air can easily overcome even the best bearing seals, and can force grit particles inside.

Just something to think about before you go spending big money on bearings.
 
HPI Bearings are the problem.

Maybe I shouldn't be so harsh but I have never had them last more than a gallon on anything and in any part of the truck. I run pretty much boca or Avid bearings purcahsed singly for $1 or so from my LHS or www.SMFStore.com .
 
Last edited by a moderator:
HopIt said:
Any bearing will fail if it gets contaminated in any way or if it runs dry. The quality and type of seal is the key. Unfortunately the diff bearings are probably exposed to more contaminents than any other bearing on the truck. They are also difficult to access for proper cleaning. Bad cleaning practices, such as blasting compressed air directly at a bearing can also cause premeture failure. The compressed air can easily overcome even the best bearing seals, and can force grit particles inside.

Just something to think about before you go spending big money on bearings.
Click to expand...

What you say about seals and cleaning and such about bearings is spot on, but I'll have to respectfully disagree about the diff bearings being exposed to more contaminates that other bearings on the truck. All bearing will get contaminated over time, but CB or axle bearings are much more exposed and risk failure than the diff bearings. (Not the pinion bearing though) The diff bearings are outside of the sealed diff and inside the closed bulkhead, so I think these are protected from contaminates about as much as your transmission bearings.

But all and all.... all bearings will fail eventually, and they are ALL OVERPRICED! 🙂

*
 
randysavagex said:
wow thats terrible I've been running the truck for a while with no prob and then bang. Do you have a link for the upscale bearings I'd appreciate it.
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Do you mean that it happened without any signs oh wear & tear in the bearings? All looked OK before you had that? Did you ever check for any play of the diff.? Maybe it needed shimming? It worries me and it propably means we have to change bearings as preventive maintenance. I've gone through a 1 1/2 gallons and all looks OK....
Thanks
Thanos
 
Thanos said:
Do you mean that it happened without any signs oh wear & tear in the bearings? All looked OK before you had that? Did you ever check for any play of the diff.? Maybe it needed shimming? It worries me and it propably means we have to change bearings as preventive maintenance. I've gone through a 1 1/2 gallons and all looks OK....
Thanks
Thanos
Click to expand...

If it goes, it goes. Keep some spare.
I have never blown out a diff bearing. Stock or CEN.

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Yes everything looked fine no sign of any problems. Since hpi made them easy to access with 6 screws I have pulled them out almost everytime I ran it. Thanks for all the replies and help!
 
Ive had these fail twice. It is a combination of bearing design (Large inside diameter vs outside diameter = small ball bearings inside) anything goes tolerance in manufacture and the fact that they are side loaded from the pressure on the ring gear.

Really HPI should have used a larger outside diameter with larger balls inside with deeper races.

Since we don't have the choice of using larger bearings the best thing to do is to use a high quality bearing that is manufactured under stricter tolerances.

The better bearings may cost more but will save the cost of new gears and the hassle of losing use of the truck. Not to mention the waisted time repairing it.

I'd much rather spend my weekend playing with my savvy than having it go bust and go home frustrated.
 
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