1987 N/A. Yes, I'm an RX-7 noob and I have read the FAQ... still gettting the main kinks worked out of this foreign machine before creating a N/A beast

1) Clunking/Grinding sound downshifting from 4th into 3rd... doesn't do it in any other gear... bad syncro?

2) After cold start... engine starts to 3,000 rpm, does its thing for 17 seconds or so and works down to about 1,500 where it tends to do the 75-100 rpm dance (read: erratic, fluctuating, pulsatiing, whatever). Once warm, it seems to do okay. Depressing the clutch and turning on the A/C will rid the rpm pulsation. What is this? Probably 10 different things, right?

Thanks in advance.

 

1. probobly a syncro. they're fairly delicate (or at least old) in these transmissions, but if you take it easy and maybe double clutch on that shift, its nothing to worry about much.

2. its normal, the car does that to warm up faster (covered in the FAQ sticky). it can be dissabled by holding the gas 1/2 way down when you start.

 

I understand the accelerated warm up on a cold start... 3,000 rpm, and whatnot. But is the fluctuation in RPM normal after the 3k start?

 

On the tranny, I had the same problem with mine when I first bought it. I got really tired of it, so I pulled the tranny apart. Turns out the input shaft to main shaft bearings were worn out allowing the shafts to flex. The synchros look great and now after rebuild, the bump is gone. If double clutching doesn't solve it, its most likely the bearings.

 

1) Bleed your clutch. Replace your shifter bushings/boots. Change your gearoil. Its worth a try prior to removing/rebuilding the tranny. Use a quality gearoil like Redline MT90, Amsoil MTG, SpecialtyFormulations MTLR, or RoyalPurple Maxgear.

2) Do a tuneup, clean all electrical power and ground connections, and check for vacuum leaks. High RPM starts are normal. Engine should idle well when warm.

 

The clutch was bled about 4,000 miles ago when I replaced the clutch reservoir. I'll bleed it again and change the shifter bushings when I install the short throw shifter. Hey all, thanks for the ideas. It's not a huge problem; more of a nuisance when I get the "world is my racetrack" itch.

 

About the idle... just came off a fresh tuneup... was out checking for vacuum leaks today with a tube. Didn't clean the grounds or power connections... will get on that soon... maybe that will help the 3,800 hesitation thing also -- probably not though. ha.

 

The double clutching doesn't help with the grinding downshift into 3rd. And yes, I'm a good double clutcher because I drive a very big truck over the road all week. Will figure it out soon enough.