Well, I was driving the 7 over to the Gf’s place when I came to a stop to make a right turn. I made my turn, shifted into second and gave it about1/2 throttle. All of the sudden, I hear a sharp cracking sound (like a piece of wood being snapped) followed by an intense grinding sound coming from the engine/transmission. The whole car was vibrating with the grinding noise.
I pull over immediately, and kill the motor. I know I lost power, so I was thinking might be motor, might be transmission. GREAT!!!
I start poking around, and I don’t see anything (no leaks, no obvious damage).
So I figure if it’s the motor, it would probably not start, run like a bag of sh*t or worse. So I fire up the motor, and it starts fine. But the grinding is still there. I shut it down again.
I’m starting to think it may be the transmission / clutch.
I started the car again without depressing the clutch this time. Now it sounded like it had a hard time starting. Something was catching even though the shifter was in neutral.
Now I’m thinking transmission. Tried to limp it home (I was about 1mile from my driveway) it took off fine, but the minute I gave some throttle, it started grinding more, and didn’t pull forward any more. I was able to get the car up to about 25mph using 1st and 2nd with about 5% throttle. The weird part was, when I let off the throttle, I would be in gear, but the motor would drop to idle, but the car would maintain speed.
I have yet to tear into it, but I will pull the transmission first…

Any Ideas as to what it may be?
Is there a known weak point in the stock transmission?


The car is a FD with a stock motor, Upgraded intake, turbo back 3” exhaust, FMIC, Boost controller @ 13psi HKS ecu tuned to match the upgrades.
The clutch is an OS Giken dual disk. Stock 5-speed

 

Id pull the tranny and take a look at the clutch. Look for broken clutch fork, pivot ball, TOB, engagement collar...

 

+1 on clutch fork or clutch related..

 

I wouldn't immediately assume it was the motor...seals don't make loud cracking sounds when they break, atleast not to my knowledge. Most of the stories on here are a "feel" thing, like lose of power or hesitation when a motor goes south, but if you had some loud bang booms going on and loss of power as well, my vote goes for something in the bell housing/tranny.

jack the car up, get under and remove the little cover plate on the bell housing, 2 10mm bolts. Look up into the upper driver's side corner of the bellhousing and check out the fork and whatnot. Maybe feel around to see if anything is sitting loose in there as well. Take you 5 minutes to check it all out.

 

+1 , check the little cover plate , open it and check maybe with a small flashlight , you might be able to pinpoint that problem

 

If you dont' see anything funny inside the clutch cover, then drain the tranny oil and remove the big rectangular pan in the middle of the tranny. You'll know if you crunched a gear in there.

Dave

 

+1

I wouldn't just drop the trans immediately, sounds like a lot of work when the FD has some fairly good provisions for checking things over inside the bell/gear housings!

 

Just the pan, not the transmission.

 

Ya, I forgot about those inspection covers. Ive had access to a lift for the last couple of years, so pulling a tranny is no big thing.

 

+1 on the clutch

 

Well, I had popped off that little inspection cover, but I didn’t see anything out of the ordinary. The OS Giken twin disk clutch I have uses 2 solid sintered iron discs. I was expecting to see one of those shattered (This had happened in my Nissan 300ZX TT). I looked in, and everything seemed fine. So I figured, guess its time to pull the transmission, because there must be a problem with it. I went ahead, dropped the trans out of the car (yup, I do this **** on the driveway). I had it out within 1.5hours. Now here is the issue! The clutch and flywheel dropped out with the transmission!!! I had sheared off all 6 flywheel bolts!!! I had to drill holes in the leftover parts of the bolt that were stuck flush to the eccentric shaft (not an easy job – remember, this is all going down on the driveway!) 8 drill bits and 2 hours later they were all out. This is where the good news comes in. Total cost of this repair $18.04. I got new bolts (grade 10.9 I think…?) and that’s it. The clutch is still healthy, I checked the transmission, and it was fine. That’s all! Here is the pic I took once I separated the engine and transmission.

 

Wow, all the bolts broke. I could understand one or two, but all is nuts.

 

Wow, that's crazy, but lucky for your wallet!

so, what exactly would cause something like this? improper torque (or lack of) to the 6 bolts on the flywheel/pressure plate?

 

Was there locktite on them? Make sure to put it on the new bolts your installing. If you havent already.

 

Wow. So...why did they break? Did you order the bolts that broke from GhettoBolts.com or something? Is something misaligned causing undue stress on those bolts?

 

I have no Idea as to the cause of this. I haven’t ever driven the car hard. Judging by the mods, this was probably an all out drift/race car in Japan, so it probably did take a beating there. But the truth is, the bolt(s) finally let go while accelerating in second gear @ about 1/3 to 1/2 throttle...

Now I’m all sore from doing the transmission job, but still enjoying the 7!

 

Well there's your problem! :P

These cars were meant to be driven hard!

Remember, a redline a day keeps the carbon away!

 

you got really lucky those bolts came out. otherwise you'd have to either let a machine shop take a stab, or need a new e-shaft.

congrats on the job well done, $18 for repair and good as new..... you have much more patience than i do when it comes to broken studs/bolts

 

this is amazing and 100% sheer luck that nothing else was wrecked in the carnage. You should buy a lottery ticket.