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Re: Survey: Cause of pinion bearing wear? Posted by Kevin K [Email]  (#374) [Profile/Gallery]
(more from Kevin K) on Fri, 3 Nov 2000 13:53:51
In Reply to: Survey: Cause of pinion bearing wear?, Todd 83-900T, Fri, 3 Nov 2000 09:24:35 Members do not see ads below this line. - Help Keep This Site Online - Signup |
My 83T pinion started dying at about 65000, shortly after efforts to maximize low end torque were done ... lots of fun until ...
As I inspected the pinion brgs and carrier sent back by Eriksson's, I did some calculations, and talked with Nat about a larger mega bearing retro-fit, which he now offers.
Since I did my box at the earliest indications, I could see early signs of classic spawling of the races ... suggesting overload and/or too thin an oil. The maximum bearing force occurs in 2nd or 3rd gears for turbos, depending on things. But 4th and 5th provide loads more of the time. Bottom line it all contributes.
Failure is related to preload (can vary), dynamic load history, and lubrication. Too little or too much preload can increase peak loads on the front bearing of the pair. Dynamic load goes up with boost. And for lubrication ...
NTN Bearings Inc recomends around 10-15 cSt viscosity for our tapered roller bearings, at 50 mph and from 60C to 100C. MTL and 10W30 oil hover around 10 cSt at 100C, 212F. 75-90 gear oils are between 13 and 24 cSt at this temp.
With hard driving, gear box oil can get to 250F. Once this hot, visc is lower, mabe by 5 points. This is where the 75-90 has a place. But for cars at lower power, and not driven hard, this would be needessly thick.
, Fri, 3 Nov 2000 13:53:51 <-- Viewing This Message, Fri, 3 Nov 2000 17:16:15
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