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Hi all,
My gearbox needs a rebuild as the syncros are slowly dying.
I have spoken to my mechanic and he recommended a place which only does transmissions in "Revesby" (Sydney) ..... he believes the stores name is "Mazbit" or "Mazbyte" .... but he's not 100% sure on this.
Does anyone know this particular store and can provide me their number or else, recommend another place in Sydney for a gearbox rebuilt for my 5??
Cheers
Robbie

hrmm.. i wonder how much it'd cost? i think it'd be a fair bit to rebuild with all the labour involved. it might be easier and less headache to get another gearbox (preferrably an SE one if you drive your car hard)

Thats what I was thinking...

NB8B boxes generally go for less an $1000, but Id still be interested at how much a rebuild would cost.


Try giving justjapanese auto wreckers a call, from memory they had an NB box?

Hard to guarentee the condition though.

Hey Robbie,
When you say the syncros are slowly dying are they crunching going back through the gears or snicking when changing up?

I spend my days doing up diffs and gearboxes and mate , many transmissions sent to me are fine except for a tarnish build up, causing slow syncros, a good flush and replacing the oil with a semi synthetic 75/90 oil will do wonders.

If the syncros are stuffed, allow approx $2500 to do the box properly (guesstimate) for new genuine syncros and bearing, probably linishing of mainshaft and labour.

Unless the car has been well and truly mountain dríven or used to teach little sister to drive, I'd be surprised that it would need syncros.

Try the oil change first, it's a lot cheaper

Terry

Just as a bit of further info ... Bruno at Maranello Motors in Melbourne re-built an NA8 box with noise and synchro issues for me last year. For just over $400 he replaced all (5?) bearings and seals, adjusted the linkage and shimmed a couple of cogs. The box was perfect after that until I tried to slam it into reverse at about 180.

Ref SE GB, there was one on ebay until recently for which I think the starting price was $2300.

tbro wrote:Hey Robbie,
When you say the syncros are slowly dying are they crunching going back through the gears or snicking when changing up?

I spend my days doing up diffs and gearboxes and mate , many transmissions sent to me are fine except for a tarnish build up, causing slow syncros, a good flush and replacing the oil with a semi synthetic 75/90 oil will do wonders.

If the syncros are stuffed, allow approx $2500 to do the box properly (guesstimate) for new genuine syncros and bearing, probably linishing of mainshaft and labour.

Unless the car has been well and truly mountain dríven or used to teach little sister to drive, I'd be surprised that it would need syncros.

Try the oil change first, it's a lot cheaper

Terry

From 1st to 2nd i'd get a bit crunch, it helps when i pause for a second or two between shifts....

I have been using castrol oil for the past year or so, then switched to red line light-weight shockproof. The red line oil helped for about 1000k's then it just feels the same again.

When down shifting to 3rd from any gear (with heel and toe) it just doesn't feel right, I need to use more force, as though I need to "jam" it into gear.

My mechanic said there was an MX5 (model/type unknown) that did a GB rebuild a couple months ago for $850 at Mazbit, he said that the syncros were gone. But he did make it very clear that it really depends on the condition of my GB.

Cheers everyone =)

Have you checked the top boot for splits?
Put a splash of new oil into the top chamber under this boot where the linkages are?

Hello tbro,
What causes 'snicking' on the change up? My 1985 Swift has had this condition,2nd to 3rd, for over 100000 ks, and tho' slightly annoying, seems to be not getting any worse or indicating any other possible trouble. What causes 'tarnish'? And what is the procedure for flushing a gearbox, please? Is there a special fluid for this purpose? Also is there a particular gear box oil that you prefer to use?
With thanks in advance, John

slowpoke wrote:Hello tbro,
What causes 'snicking' on the change up? My 1985 Swift has had this condition,2nd to 3rd, for over 100000 ks, and tho' slightly annoying, seems to be not getting any worse or indicating any other possible trouble. What causes 'tarnish'? And what is the procedure for flushing a gearbox, please? Is there a special fluid for this purpose? Also is there a particular gear box oil that you prefer to use?
With thanks in advance, John

Hey John,
Snicking on gear change is caused from burrs on the syncro cone, won't cause problems and the only way to rectify is replacement.
Tarnishing is caused by not changing the gear box oil often enough and a heat biuld up especially in alloy housing transmissions, Jap boxes and diffs require new oil every 40,000ks to keep them in good nick. I think most people have heard the old whine from Mazda commericals and toyota 4wd, all caused by poor servicing. The old Mazda/ Ford vans & utes kept most gearbox specialist plenty busy back in the 80s/90s due to mainshaft failures caused by lack of lub due to old oil. The main shafts were modified by the factory something like 14 times to try and stop failures, in the end it was made a warranty procedure to prove oil was changed at 40k service or no warranty.
I don't know of any flushes that actually work, change the oil a couple of times, say every 5ks and that will clean most of the tarnish out of the box.
I use Valvoline semi synthetic oils in both the race car and the clubman, got it for free from Valvoline Seems a reasonable product. In a turbo car I will only use Royal Purple, very expensive but so are transmission rebuilds in BIG hp cars.
Hope that helps.
Terry

slowpoke wrote:What causes 'snicking' on the change up? My 1985 Swift has had this condition,2nd to 3rd, for over 100000 ks, and tho' slightly annoying, seems to be not getting any worse or indicating any other possible trouble...

If it does this when you do fast gear-changes, then it's not a concern as Swift boxes are reknown to do this all the time.
I have friends with the early model, and last model, GTi, and their boxes are still strong regardless of the graunching sound on fast changes.

Thanks tbro and 1red5 for your informative replies. In a general sense tho'when regular servicing/oil changing ect is done, what causes "burrs on the syncro cone"? Is it caused by poor gear changing techniques? Or something else? And Terry, you recommended "semi-synthetic"oil... I have been using Red Line MT-90, an "all-synthetic formula" because I had supposed it to be the best. Does an 'all synthetic' oil, in fact, not perform as well (in a modern Jap gear box) as a semi synthetic...? Or is it simply a waste of money to use the all- synthetic gear oil instead of the semi?

slowpoke wrote: In a general sense tho'when regular servicing/oil changing ect is done, what causes "burrs on the syncro cone"? Is it caused by poor gear changing techniques? Or something else? And Terry, you recommended "semi-synthetic"oil... I have been using Red Line MT-90, an "all-synthetic formula" because I had supposed it to be the best. Does an 'all synthetic' oil, in fact, not perform as well (in a modern Jap gear box) as a semi synthetic...? Or is it simply a waste of money to use the all- synthetic gear oil instead of the semi?

First off have a read on Wiki on Manual transmissions. This will help you understand how a transmission works. Without a gearbox stripped down and both of us present it can be very confusing to try and explain the workings, but I'll try my best. The burring is caused by normal wear and tear of gear changing, and can be increased by trying to select a gear at too high a road speed, resting your hand on the gearshift for long periods of time ( a bad habit to have, nearly as bad as resting your foot on the clutch) or trying to be a big trucky and not using the clutch!!!!

I use semi synthetic oils as they are supplied FREE!!!!!!!, but if I had to buy my oils I'd probably still use semi oils.

I'll try and not offend people here but I have yet to meet any race team manager/mechanic that has a good word to say about Redline oils,
BUT have found that teams pushing big torque and HP are all very happy with Royal Purple. Full synthetic oil is probably an added expense thats not required in a normal MX5, Turbos are a different matter especially the SP, heaps of added hp and nothing done to the tranny unlike the SE tranny. But it not my money so if you want to run synthetic oils go for it, it can't hurt!!!

Terry

tbro wrote:
I'll try and not offend people here but I have yet to meet any race team manager/mechanic that has a good word to say about Redline oils,
BUT have found that teams pushing big torque and HP are all very happy with Royal Purple. Full synthetic oil is probably an added expense thats not required in a normal MX5, Turbos are a different matter especially the SP, heaps of added hp and nothing done to the tranny unlike the SE tranny. But it not my money so if you want to run synthetic oils go for it, it can't hurt!!!

Terry

Hang on a minute, this sounds exactly like a conversation I had with someone earlier this week

btw I got your message re 888s, I assume that they are on 15s? may cause me a wee problem with Mr Will & Mr Wood

also probably going to be in the ND, unless the 888s are on 16s