So, here's the thing:

Recently the car started to make a slight knocking/tapping sound at idle. The sound went away as I pressed the clutch so I thought is must be clutch / trans related. I pulled the engine and it's definitely in the transmission. I verified this by rotating the transmission input shaft using an electric drill.

Here's a short clip about that:
https://youtu.be/2GAHxo7bhY4

Never dropped the clutch or did anything same kind of stupid but I cannot speak for the previous owner.

Could it be the input shaft bearing or something else? Doesn't sound a like bearing failure?

Car:
1999 WRX GC8 160kW (known as Impreza GT in Finland)
Trans code:
TY754VN1AB

Looks like I have a few options:

1. Repair the gearbox myself, cost estimate 200-400€

2. Switch to 5 speed Type r box with DCCD (ty754vb1ca). I can have the box, rear diff, axles and the DCCD controller for 1300€ (about 2000 AUD). I believe I would need R180 rear hubs and brakes but one option could be to use the "Suberdave R160 - R180 Hybrid Axle shafts". The clutch, trans & rear diff mounts are the same for all GC8's aren't they?

3. Do a 6 speed swap (not cheap!). 6 speeds go for 3000€ around here and that's not including all the other parts (clutch, slave cylinder, drive shaft, rear diff etc) And generally the parts are incredibly hard to find here. I could try to find a wreck car witch the right parts but that could take a long long time.

I'd like to hear your take on this. The future power goal is at least 350 WHP, currently at about 270. Fix the 5 spd and start saving for 6 spd? Is my power goal too much for any 5 speed anyway?

-Timo

strip the gear box and show us what's damaged

rear main shaft nut loose ?

That's on the ToDo list. Hope to get it done this weekend.

Keen to see pictures.

Been rather busy with my work. I haven't opened the transmission yet but I drained the oil today. I found something interesting on the drain plug, see the pics.

-Timo

Attached Thumbnails

   

Here is how I intend to proceed:

-Swap the transmission to Type RA, ty754vb1ca
-Use the R180 rear diff
-Use R160 - R180 hybrid axles
-Use stock rear hubs
-Use stock driveshaft by swapping the flange to the rear diff

Broken tooth

Finding a broken tooth like that is good luck, otherwise you would be tempted to dismantle the box to find the problem.
Maybe the box is repairable, but better to replace as you are doing.

The 6 speed is reputed to be much better than the 5 speed, but doubtful value considering the big extra cost.

So I went with the ty754vb1ca and hybrid rear axles. Wired up the STI DCCD cluster and the controller box. Absolutely loving this gearbox's close gear ratio and the RPMs ain't that bad at highway speeds.

Now I'm preparing to swap 268 cams & 20g... and maybe a stroker kit

When I blow up this box I'm getting a 6 speed.

That's the spirit!

__________________
Bye bye betty blue. Hello F6.