Transmission grinds at low rpm
 

Hi guys,

Would anyone know why my transmission grinds when I shift from 1st to second or second to third when the RPMs are low? Whenever I try and shift at around 2500 rpm or lower the transmission grinds from 1st to second or second to third. When I shift at anything about 2500 RPM it shifts just fine.

Things you should know, transmission probably has not had a fluid change ever or for at least 50K+ miles. Shifter feels very loose and sloppy, seems like the bushings are done for. I'm guessing where the gears are sometimes... Also Im sure that brake fluid has not been bleed for a very long time. The clutch disk was absolutely shot, it literally had no friction material on it.

I'm hoping my transmission is fine and the only issue is the fluid and bushings, if not I guess its time to get a new (used) tranny.

Moe Greene

Start with the gear oil. Believe it or not Mazda recommends 15,000 mile changes on the gear oil!

I'm fixing to try the Idemitsu gear oil, I've heard good things. It's like $8-9 a quart and you need 3 quarts.

And DEFINITELY get new shift lever bushings. That makes a HUGE difference. Super easy to do as well.

If the gear oil doesn't do the trick, you're not out much money. But I've seen good gear oil do wonders for a transmission.

Dale

I purchased a replica B&M shifter... but i have the transmission out of the car since I'm rebuilding the engine :(

Should I just play it safe and get another tranny or do you think fluid change + short shifter will fix this issue?

Also if the transmission grinds at low rpm shouldn't it grind at higher rpm if the synchro are bad? What would cause low rpm grind?

hey buddy. I have a thread about the same issue with my 94. seems like you are experiencing same as me ?

check out my video. the thread is not old. maybe second or third page.

I checked out the thread (https://www.rx7club.com/3rd-generati...1106571/page2/), my issue is different. The transmission was good when in gear, granted it has lots of play while in gear, the grinding I'm hearing is in this sequence: Clutch pedal in->shift down from 1st into neutral->move shifter from neutral to *grind* second->clutch pedal out


Now obviously when I shift from 1st to second I don't hang out in neutral, the transition is much smoother aside from the grinding. The strange thing is if i shift from 3K+ RPM it wont grind.

Anyone have and insight into this? Super curious as to why it would grind at low rpms.

Back in 2005 I replaced the OE trans fluid with Valvoline 75W90 synthetic and immediately had grinding when the trans was cold. I then switched to NEO 75W90 synthetic, and the issue disappeared, and shifting was better than it was with the OE fluid.

So, yes, the fluid type makes a big difference.