Transmission input shaft bearing....a warning.
#1
Transmission input shaft bearing....a warning.
Early last spring I began noticing a noisy input shaft bearing on my car. Gradually it got worse. I tolerated it through last summer's driving season here in the Midwest. Just figured I'd address it over the winter when the car hibernates anyway. That was nearly a costly mistake...see below:
The car/transmission has about 118K on it. The previous owner set it up for autocross and I also autocrossed it about 4 yrs. But AFAIK, it's never been tracked and it's adult street-driven otherwise. Shortly after I bought it 11 yrs ago, I started running synthetic gear oil. First (I think) M1, then Redline MT90 and most recently NEO 75w-90 HD. Didn't watch it close, but averaged about 20k miles between changes.
In a nut-shell I'm not sure why this bearing went bad, but a BIG word of caution. Don't wait like I did. When the shop got it apart they showed me the main-shaft which had been galled slightly. He was able to clean it up with some fine emery cloth, oil and time to where he felt comfortable re-using it. The shop has a good rep, so here's hoping he's right. He also said that if I'd driven it much more that main shaft would have been toast. And it runs about $500 from Mazda (Ray @ Malloy). I didn't check MAZDACOMP.
The up-side is I ended up having a pretty comprehensive rebuild with new bearings, brass, shift forks etc. Haven't been able to drive it much due to bad roads, but what little I did suggested dramatic improvement. Took the opportunity to change fuel filter while the trans./PPF and drive-shaft was out, and added a LW flywheel (thanks adamc for input)
The car/transmission has about 118K on it. The previous owner set it up for autocross and I also autocrossed it about 4 yrs. But AFAIK, it's never been tracked and it's adult street-driven otherwise. Shortly after I bought it 11 yrs ago, I started running synthetic gear oil. First (I think) M1, then Redline MT90 and most recently NEO 75w-90 HD. Didn't watch it close, but averaged about 20k miles between changes.
In a nut-shell I'm not sure why this bearing went bad, but a BIG word of caution. Don't wait like I did. When the shop got it apart they showed me the main-shaft which had been galled slightly. He was able to clean it up with some fine emery cloth, oil and time to where he felt comfortable re-using it. The shop has a good rep, so here's hoping he's right. He also said that if I'd driven it much more that main shaft would have been toast. And it runs about $500 from Mazda (Ray @ Malloy). I didn't check MAZDACOMP.
The up-side is I ended up having a pretty comprehensive rebuild with new bearings, brass, shift forks etc. Haven't been able to drive it much due to bad roads, but what little I did suggested dramatic improvement. Took the opportunity to change fuel filter while the trans./PPF and drive-shaft was out, and added a LW flywheel (thanks adamc for input)
Last edited by Sgtblue; 01-18-18 at 07:27 AM. Reason: Replace dead photo link
#4
I actually had two quarts of NEO 75w90 HD and about 1/2 quart of unused Redline 75w-90 (from diff) sitting on the shop shelf. Since this was almost exactly what I needed, I mixed them to fill it up following the rebuild. I'm assuming that it's OK to mix two brands???
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#8
Rotary Freak
All the boxes that I've pulled have that bearing brinelled, usually a nice slurry in the area it spigots as well. Doubt oil or use has much bearing on whether any one particular box will be affected....unfortunate Mazda legacy using a decades old design.
#9
There's a vid in post #16 ----> https://www.rx7club.com/3rd-generati...aring-1045877/
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Jeff20B
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