Turns out something isn't right in the diff. Could be a busted bearing that i haven't replaced. Actually i think that's what it is. Has a nice whine at about 50km/hr up.
The diff was bought off a guy who i suspect used it for drag stuff. It had a welded up centre but all the preload was off the pinion gear.
I noticed that when i torqued it up again, it added way too much preload to the bearings that made it difficult to turn the pinion flange without a socket on the nut for assistance. I decided to replace some bearings at that point.
I replaced the rear pinion bearing (closest to the crownwheel) because i thought that bearing would be the one to flog out first (it was exactly the same height as the old one in the race). But it was still too tight so i only torqued the preload to about 55 ft lb. After speaking with a few guys, i think that the conical piece and the spacer between the front and rear pinion bearings is too short, allowing too much force to be applied to the bearings.
Once i added the centre i could only set the backlash using the shims i had.
It was on the high end of the tolerance and i think that would contribute to some of the noise also. Wipe pattern and mesh looked central so i was happy with that.
Without a bigger selection of shims and spacers i don't think I'll get this thing setup right, so unfortunately (and disappointingly) I'll probably have to take it to someone to look at.
Trent, no movement on the exhaust yet. I'm not sure if i mentioned but i took the car to performance exhaust centre and spoke with the owner who has a very nice black 1600, he suggested putting the std manifold back on. Basically said that not only will my stainless one crack eventually, it's also not designed for the turbo i have (t28) and the whole inlet and outlet of the engine will contribute to its overall sound.
He also said that they flow well enough standard anyway so unless I'm making over 250rwkw then it won't impact upon my final power figure.
So that's next. But when i do that, i also want to take the head off and fix the oil leak coming out of the timing cover... will replace the head gasket with a metal cosworth one (when i work out who supplies them) and probably do a bit of head work while it's off...
That's the plan
Ongoing Project: 1972 Datsun 510 S13 SR20Det. http://ozdat.com/forum/viewtopic.php?f=33&t=17898
New Daily: D22 Navara (The new workhorse)
Retired 12/2016: MY98 Subaru Impreza RX
Previous Car: Restored Green 1972 Datsun 510, Hot L18