Hi Mark,
iv'e built a fair few gearboxes.
To Keep it short and not to technical i would replace the detense and the 3rd gear synchro as in most boxes 3rd gear is the one that cops the bigest hiding.

Good luck with it

Charles

Hey Mark
Glad to hear your 5 speed came with new synchros
Cheers
Mal

I run Redline Super Lightweight (yellow) in my racecar and will not use anything else now. Did use Syntrans in the early days but it ate my first close ratio 260Z box ......
The Redline works well for us - and at about $25 - 30 a litre it won't break the bank for a small volume box like an A series.
Cheers.

While we are on the topic, how much oil does a 60 series box take?

Did you check the surface condition of the synchro cone on the gear? I find they can get nicely glazed and the cones then lack real bite on the gear. Spinning it up slowly in the lathe and breaking the glaze with a very fine very flat stone does the trick. Agree that a mild bead blast to the friction surface of the ring is well worthwhile. It helps to have a few rings to choose from as sometimes the mating angles are not perfect.
Get it all right and they really bite hard. Also last a lot longer as they don't slip near as much.
Hope this helps

Yes the roughed up cone will work but like you said it will soon polish out - but for a super light rotating assembly motor, it would allow real quick shift speeds - at reduced syncro life.

My thoughts too were about the energizing lugs, they wear and round over allowing less force being exterted - so I said wind a stifer spring/or you can replace them.

I can tell a slight difference in selecting 3rd then say 4th or 2nd - tiny bit less resistance (3rd has more wear on the lugs) unless thats just me thinking it is.

On a positive note, it seems that more driving is fixing the problem! It "sounded" like the dog gear skipped 5 or so teeth and now it "Sounds" like its only skips 1 or so - the crunch turned to a more of a instant dull click - hard to explain but its definately better.

Oh and the 1.6mm sounds huge but when I opened the box I noticed some else had been in it before (sealant, bolt heads) and theres new syncros all round! It may have crunched before and they tried to fix it, I dont know. They could have changed the energizing lugs for me too, sheesh...lol.

Nah, I was stoked with that and I did the bearings and seals.

The purpose of speeding up (or slowing down) the gear is not entirely left up to the synchro ring on it's own, but also the energising lugs and springs play their own part as well. What series gearbox are we talking about here? 1.6mm sounds fairly high for a 60 series, more like a 71 series, either that or they are like new.

Roughing the surface of the dog cone will certainly help but it will be short lived. It will polish out soon enough. Some cones have their own machined grooves that allow a place for oil to travel to allow a harder grip between the synchro and the cone. It offers a lessened surface area for oil at a reduced syncro life as the trade off. The problem you have may not lie with the synchro or cone itself but maybe with the energising lugs. As they get older they wear the square shoulders off the tab and offer less resistance to the selector ring as it applies the pressure to the energising lug to the synchro. The energising lugs release earlier while the gear is still being selected and it can cause some short lived grinding as a result of the gear speeds not being matched correctly.

It's a tough one to call over the phone but the oil is the easiest way to try and sort it out, before pulling the box apart.

How would you guys rate the Penrite 75 against Redline shock proof?
Just wondering cause the Redline oil is sooo expensive at $66/litre!

+1 for penrite 75. Reccomended to me by benny.

Very very, happy with the results.

That is my first step (last is pulling the box apart again!).

This weekend I will look into a good mineral oil and see how that goes.