Oh No Syncro problem

zbloke

Club Member
Tim the point I am making is a primitive Nissan box that is now around 40 years old is probably fcuked. The clue being Andrews description of what he saw when the drained the old oil out.

Pete, thats very true, it could well be, which is why I put

The damage could already have been done though

Regarding what Andrew saw when he drained the old oil, I've seen lots of drain plugs with slivers of metallic swarf on them and the boxes have worked fine......its when you have bits of gear teeth, springs and ball bearings on the drain plug you've got issues

IMO of course
 

RIDDLER

Well-Known Forum User
I had the same synchro problems in my 260Z. Managed to source a secondhand 260Z box on the net, but when fitted it was not a lot better. Eventually got an excellent place in Liverpool called Top Gear to take apart both boxes and build one good one from them. This work included turning round a couple of the synchro rings - total cost of the work was £250 and the gearbox is now very good.

Top Gear strongly advised against using Molyslip or that Slick stuff in the box, by the way.

I believe the best oil to use in the box is a semi-synthetic 75/90?

Good luck - a bad synchro is really annoying I know.
 

andrew muir

Club Member
Hi
Followed your thread from a while back.
Its getting the parts which seems to be the problem.
The place in Liverpool sounds like good value considering the work and skill involved.

It is weird how this has happened all of a sudden though, after the oil change! had no issues before so is not a progressive thing, and the down shifts seem to be ok which is even more weird.
Will try and put different oil in tonight to eleminate that as the mechanic which helped me thinks the new oil not enough friction to spin up the worn syncro.
I also wonder if clutch may be dragging a little.
Andrew

I had the same synchro problems in my 260Z. Managed to source a secondhand 260Z box on the net, but when fitted it was not a lot better. Eventually got an excellent place in Liverpool called Top Gear to take apart both boxes and build one good one from them. This work included turning round a couple of the synchro rings - total cost of the work was £250 and the gearbox is now very good.

Top Gear strongly advised against using Molyslip or that Slick stuff in the box, by the way.

I believe the best oil to use in the box is a semi-synthetic 75/90?

Good luck - a bad synchro is really annoying I know.
 

RIDDLER

Well-Known Forum User
I realise Peebles is a hell of a drive from Liverpool, but I can't recommend Top Gear in Liverpool highly enough. If you can drive to them they will whip your box out faster than you can blink and find out what is wrong with it. The guy to speak to there, who runs the place and is incredibly helpful, is Ernie who is the owner and really understands boxes from older cars. Phone: 0151-726-1777. He might even give you advice over the phone?
 

Nigel Brook

Well-Known Forum User
Have you considered the long shot possibility that it's not the gearbox that's the problem but the ciutch. Outside chance it's loosing hydraulic pressure when under load ie when the pedal is pushed.
 

andrew muir

Club Member
Hi Nigel
It is a possibility, not sure how to adjust will read up on that and give it a go, although other gears are ok and engaging first is no problem.

To update further I have put in the Redline MT90 oil up to the filler level and first impressions are that it is not a miracle cure but seems about 20-30% better can now rev till 3000 for quick changes and 4000 if I take it a bit more slowly. It will still grind above that but somehow not quite as much.
I have to add that due to the constant rain here, this was a very short test and the oil was probably not at full temp.
:unsure:


Have you considered the long shot possibility that it's not the gearbox that's the problem but the ciutch. Outside chance it's loosing hydraulic pressure when under load ie when the pedal is pushed.
 

Nigel Brook

Well-Known Forum User
Hi Nigel
It is a possibility, not sure how to adjust will read up on that and give it a go, although other gears are ok and engaging first is no problem.

To update further I have put in the Redline MT90 oil up to the filler level and first impressions are that it is not a miracle cure but seems about 20-30% better can now rev till 3000 for quick changes and 4000 if I take it a bit more slowly. It will still grind above that but somehow not quite as much.
I have to add that due to the constant rain here, this was a very short test and the oil was probably not at full temp.
:unsure:

If it is the clutch more likely duff seals than adjustment if it was ok before the problem. Check for leaks around the slave cylinder and under the dash at the back of the master cylinder.
 

andrew muir

Club Member
Hi Nigel
Had a look yesterday, definately no leaks from master and slave cylinders, but did discover rust in bulkhead which when proded produced a 2 inch rust hole,:lol:Going getting welded in next couple of weeks.

Had the car out last night for a more vigouous run, syncro problem now seems to nearly have disappeared with car almost no cruntching until very high revs 5000 plus. No cruntching at all if not rushing changes to above 4000 so can live with that.

What it does prove though is that oils make a major difference to the operation of the gearbox, the conclusion being that Redline MT90 is better than Millars TRX in a S30 5 speed box.

By the way when I changed the oil again there was basically no iron found on the magnet.
Andrew
:)
 

Mr.F

Inactive
Link is to brass toothed synchros - not suitable for any S30 box supplied for the UK market...
 

andrew muir

Club Member
Looks like I am pretty knackered then,:eek:
Just had a big drive, 200 mile s today, box is getting progresively worse.
Spoke to gearbox specialist who said he couldn't do much without parts.
So if anyone has spare syncros or a spare box interested in buying, or Pmac one of your conversions although not many s14 boxes about either.
Help!
:(

Link is to brass toothed synchros - not suitable for any S30 box supplied for the UK market...
 

Mr.F

Inactive
I know of a 260Z box - condition unknown (to me anyway; the owner might know better), but down in deepest Kent...
Worth a punt if you can arrange pick-up?
 

racer

Club Member
Andrew you could try and just turn the syncros round. I did that a few times with mine and it cured my issues for a while. Only a short term fix though. S14 box is the way to go.
 

andrew muir

Club Member
Hi Mike
Why are the UK boxes different? I would have thought the 5speed american boxes were the same as 5 speed uk. My sister is in the st6ates and is coming over in 3 weeks has agreed to act as courier for parts if need be.
Come on then PM me the owner, I take it it is up for sale, even if not perfect some of the lesser used syncros could be put in eg 3rd -4th etc. Does it include the bell housing or just the box itself?
Ta
Andrew

I know of a 260Z box - condition unknown (to me anyway; the owner might know better), but down in deepest Kent...
Worth a punt if you can arrange pick-up?
 

andrew muir

Club Member
yep looking out for one of them,
do R33 sysncro rings fit the old 5 speed porshe type box?

Andrew you could try and just turn the syncros round. I did that a few times with mine and it cured my issues for a while. Only a short term fix though. S14 box is the way to go.
 

Mr.G

Club Member
Make sure you have fitted new synchros and bearings to whatever box you decide to fit. Don't go on anyone's visual inspection, get it done or take your chance which could mean being in the same situation you are already in. This goes for the S14 box too, newer doesn't necessarily mean it's going to be in better condition then what you already have.
 

andrew muir

Club Member
Thanks George
Would be getting any box rebuilt anyway, would hope 200sx box would be in better nick but a lot will have been thrashed I guess.

Make sure you have fitted new synchros and bearings to whatever box you decide to fit. Don't go on anyone's visual inspection, get it done or take your chance which could mean being in the same situation you are already in. This goes for the S14 box too, newer doesn't necessarily mean it's going to be in better condition then what you already have.
 
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