Red Line 75W90NS, have heard this stuff improves the dreaded 2nd gear crunch, anyone had success to validate ?
We use redline lightweight shockproof oil in both rally cars, expensive but I've been impressed with how long it lasts and the reduced wear on the syncro rings. As far as reducing the second gear crunch, unfortunately I don't think there is going to be a magic "pour in" fix, it's box out and replace the syncro rings (at a minimum). If you do, be sure to get the good quality rings, plenty of poor reproductions out there
I can only agree with Colin. I used to have a slow synchro in Second gear, and tried the redline test. It didn't improve. I eventually pulled the box out and changed the synchro ring and while at it modified first gear to stop the standing still delay. The box is fabulous now. Still using redline, and box is super smooth.
Is it possible to flip the synchro ring from 5th to 2nd, as a quick fix**, in the Nord box?
(I've done this many times in Sud/Sprint boxes)
** while you save up and consider all the parts/re build options.
Yes. You can also use the 'back' side of any ring in any position to get a new 'major' surface. But with the box in bits why not replace at least the 2nd and 3rd rings with new, good brand, ones (at about $120ea) and change the two needle rollers for few dollars more. While you are there change the selector rod oils seals (stock bearing shop item) and the box rear and front seals. Box rebuild for $300! The only bearing I have needed to change (once) is the centre layshaft roller, and that is after years of punishing tarmac rally shifting. Just make sure to tighten, stake and loctite the layshaft end nut--they have a habit of unscrewing themselves.
I'm stocked up some Red Line 75W90NS for when I next get under the car. I was told you can use it for the diff as well?