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OK, here it goes.

When I'm in first gear going about 15-20 mph then I shift to second I hear this loud bumb/knock sound like if I ran over a rock or something. It's right after I shift from first to second, and YES I know how to shift. It does it everytime I shift into 2nd. At first I always thought I was running over a rock but I finally realized it today... I'm slow Anyways anyone know whats up with that?

P.S By the way I have no grinding in any of the gears.

 

hrmmm i believe its the 1-2 crunch problem maybe? thanks kris!

 

First, start by changing the tranny gear oil. Use something like Neo or Royal Purple (my personal choice).

 

The second synchro is a double-cone design. Mine is in rough shape too, and if it gets worn I think instead of directly grinding against the clutch sleeve teeth (like a std synchro) the cones will slip abruptly. Try double clutching from 1st-2nd (1st, clutch in, neutral, clutch out, clutch in, 2nd, clutch out) - it's not too hard and will reduce wear to almost zero. If you notice the double-clutch makes the shift smooth, that confirms the synchro wear issue.

Like Mahjik said, changing oil is never a bad idea. But try the double-clutching too and see if that eliminates the problem going into 2nd. You can double-clutch it forever without really having a problem.

Dave

 

its not a grinding sound though. its like a bump sound. just like if you were to run over a rock.

 

The 1-2 crunch isnt a grinding sound, it is a 'bump' or 'clunking' noise... pretty common in FD's, Preludes and Mustangs, not to mention many other cars.

Replacement fluid is suggested... using Redlin MTL or NEO is reccomened, although both are hard to come by in our area.

~Kris

 

Redline MTL is too thin. If you use Redline products, use MT90.

 

My mistake Mahjik, I knew it was one of those. Now head over to my Synchromesh thread and help me, I'm sure it is the same situation.

~Kris

 

"the cones will slip abruptly" sounds like a bump. It will grind sometimes if you really force it fast. Double-cones can handle much more torque than standard synchros, but at a price in smoothness. 3rd has the double-cone too. Try the double-clutch to confirm that it is synchro friction you're feeling, switch gear oils if you want to make it smoother.

In other words, I think it's normal unless you have to go out of your way to make a 1-2 shift properly.

Dave

 

Nix that. I finally noticed you said 'after' 2nd. Once fully shifted into 2nd gear, there shoudn't be any transmission parts free to move or make noise when you engage the clutch - everything in the transmission is already in synch. So maybe it's a throwout/pilot/clutch problem that is only coming up on 1-2 shifts. Or, something is loose in the gearbox that is only free to move and slap around when the shift fork is in 2nd position (1-2 select fork). Neither of them sound good.

Does it happen on every 1-2 shift? Does the pace of the shift affect it? Does double-clutching solve or reduce it? Did it begin happening suddenly?

Get it checked out soon. You'll definitely want to talk to a tranny expert and if they aren't RX-7 tranny guys, inform them that 2nd is a double-cone synchro. Dave at KD rotary I think has immense experience with these gearboxes, if you're looking for someone to call. (Cam at Pettit as well, and many others). They might call my theories trash, but either way they will know.

Dave

 

alright ill have to makesure to order some redline oil from rx7 store (i believe they have it).

hrmmm here is my what-to-buy/do/fix list for my car if anyone cares which you probally dont because you probally have problems too

***REGISTER THE DAMN CAR***
1. get my boost pills for wg and pc
2. fix my exhaust/turbo/manifold leak
3. new battery and battery cables
4. new plug wires
5. a nice engine clean
6. enjoy it and do lots and lots of spirit driving.

 

I would also suggest:

* Change oil & filter
* Change tranny oil (as mentioned)
* Change diff oil
* Flush coolant
* Change O2 sensor (use anti-seize)
* Change spark plugs (with your new wires, use dielectrical grease with them)

Along with your fixes, that will give you a good starting base for the maintenance car.

 

And fuel filter.

Dave

 

i already changed my oil, coolant, sparkplugs. i also need new air intake filters badly

 

Try Differential bushings.