I posted this on the NSCC forums so certain references to peoples cars may not be relevant here.
With the help of
The Engine Whisperer (DumHed) we finally got the S14 5spd installed into MY S15.
First things first though.
Now according to most things you read on the 'interweb' to do an S14 5 speed conversion in an S15, all you need is the box, clutch and tailshaft.
But in reality, that list is no-where near correct.
So far I have found you need the following when doing the conversion
* S14 manual gearbox. - I've used a box built with a PPG 1st to 4th Helical Dog which comes with the billet selector forks and it also has the billet mainshaft
* S14 Clutch and flywheel - I opted for the ORC Twin Plate - ORC-559D-02N
* 8 x S14 flywheel bolts - nissan sell these for $22 each
* All 11 S14 bellhousing bolts - If you don't have these you will need to buy them as you can only re-use the top 2 bellhousing bolts from the S15. I sourced my bolts from a combination of Shane's car and Nepean BoltMaster
* 2 x S14 starter motor bolts
* S14 gearbox crossmember - Again stolen from Shane's car
* 1 x spigot bush
* 1 x C's Short Shifter - Thanks CaBS
* 1 x S14 tailshaft - I used Shanes old one, but as far as I can tell you need the front half of the S14 one.
* 1 x S14 Exhaust hanger/mount - If you don't have one of these you can modify the S15 to fit just by drilling 2 new holes in the mount which will then line the mount up perfectly which is what we ended up doing.
* 1 x S14 gear knob
Now for the important stuff
I took the car for a drive today and whilst it is a helical cut gearset, the box does have a whine. Its not obnoxious like in a straight cut box, so its quite easy to live with. Infact I think it makes the car sound quite tough, without being stupidly loud.
Clunks - oh my got, if you think your car has clunks, come for a ride in my car now, changes from 1st to 2nd are now the worst and I can see why people don't recommend driving a dog box everyday in traffic. Its a lots of work.
On the Advice of Andrew I was double clutching when downshifting and that seems to work ok. A little blip of the throttle to roughly rev match and its not too bad (but still clunks)
I have also found that the ratios are fairly longer than a std S14 box
STD Ratios: 3.321/1.902/1.308/ 1.00 / 0.838
PPG Ratios: 2.62 / 1.73 / 1.28 / 1.00 / std
Now I haven't done too much testing with this as I have only really driven the car once, but I did see that I did hit 60 in first gear but I am not sure if it had anymore in it as I was too busy watching the other traffic and worrying about trying to change gears. I think maybe a shorter final drive will be next on the agenda.
But enough of the bad stuff. When you are giving the car a bit of stick, and you slam it into gears whilst using the clutch its a good feeling, now clutchless shifting is just another world, it feels awesome, I never thought changing gears in an Silvia would feel or sound like it does when doing the clutchless shifting, i guess the sound has a bit to do with the slight whine the box has now too.
Overall I am fairly happy with the conversion. I guess I am just happy I can drive the car again after it being off the road since January.
The next thing on my agenda to look at is the fact that my drivers side window now does not work at all, which limits where I can drive the car to and also means that if its raining I cannot drive the car as the window does not wind up. I ran a multimeter over the wiring and can see the regulator getting the correct power from the switches, so lets hope I can just replace the regulator and it will be fixed.