Rebuild a gearbox or get another one

[dzammit85]

Hi everyone, so I just got my car (nb8b 6 speed) back from the mechanic, he told me that the syncros were on there way out, he said that they would cost around $600 to fix plus labour
What I'm wanting to know is

Am I better of rebuilding the gearbox and doing some upgrades to it to make it stronger

What upgrades, if any, can be done

Or, I seen that mx5 mania charge $1200 for a gearbox on there website, so should I just buy that

Right now I'm budgeting for the $1200 plus the labour to remove and re install the gearbox

Any suggestions on what I should do within that price range would be great
Thanks

[NitroDann]

Right now, the efficacy of rebuilding a 5 speed is "lol no", and for a 6 speed its borderline unless your gearbox guy is really good, and wants to charge no more than a good used box.

But, are the synchros really flogged, or does it just feel notchy when cold?

Dann

[dzammit85]

The 1st 2nd and 3rd gear all stick then once they finally go in there is a bit of crunch
I originally thought it may have been the oil, so changed it to some redline, but that didn't do the trick

[rascal]

Rebuilding your own gearbox gives you a known qty for $600 +labour.
Purchasing a second hand unit gives you an unknown qty for $1200 + labour.

Suggests getting your own rebuilt is both cheaper and less risky..

(Assuming your mechanic knows his stuff)

[dzammit85]

Hey dan, I only just joined this forum but within this couple days I've been on here have noticed you have quite the rep, I was wondering would you have any good 6 speeds laying around that you would want to sell

[NitroDann]

Rascal I'd suspect much more than 600 in labour to remove and refit, and rebuild.

OP: I'm sorry I have no gearboxes.

[dzammit85]

ok thanks for all your help, guess ill be looking for another gearbox, i will probably end up getting it from mx5 mania as I'm sure they aren't going to sell me a broken or worn one

[oztrackdays]

What is the going price for a "Crate" Gearbox ?

I heard that the replacement synchro's seemed to be even worse quality than the OEM originals ?

[greenMachine]

$600 equates to probably at most five hours labour. If your mechanic is very familiar with these gearboxes, that might be realistic. If he is not it is not. And that assumes that he does not have to take the gearbox out or put it back in.

On top of the $600, you would have to add parts. It sounds like new synchro, you would be mad not to put new bearings in it while it is apart, and there may well be other unexpected things found. Never having rebuilt a gearbox, I have no idea how much the parts might add up to. However, I could easily see another $600 in parts. I think that you need to get a more detailed and comprehensive quote, certainly including all the essential elements of the rebuild your mechanic envisages, and the parts cost for "good idea" replacements like bearings, together with an idea of other possible parts that might need replacing when the gearbox is open and the components can be inspected. I doubt that adding these parts will add substantially to the labour cost, but I could be wrong.

The upside is that you will end up with a gearbox in "as-new" condition, ready to go for the foreseeable future. The downside is that you may not keep the car that long, and that it may cost more than a second-hand box.

While you are considering this, I would try both a second opinion from another mechanic, and also do some searching on the different gearbox oils that people have used to improve the shifting. Sometimes redline works, sometimes other oils work. Gearbox oil is not cheap, but it is cheaper than a replacement/repair, and it would be worth trying a few of these to see if that can improve the situation.

The other thing to check is the small bush that sits at the bottom end of the gearlever, that it is in good condition and is not affecting the gearchange operation.

Additionally, you are the one that is driving this car. It would be worth driving it for a while before you do anything, so that you can form a better opinion about how bad you find it, and whether different gearchange techniques can be used to minimise the impact of any gearbox problems. It would also be good to have a drive of a couple of other similar cars, focusing on their gearchanges.

[dzammit85]

hey greenmachine thanks for your insight,

yeah i changed to redline though that didn't work, i done that at the same time i changed the gear boots as they were torn and i had read around that they could be the problem, the bush at the bottom of the liver was fine so didn't replace that, only thing i haven't done is tested other oils, though I'm not so sure that it will improve the problem, because i did feel a difference after i put the redline in, the gears that don't have any problem were real smooth, probably a bit too smooth for my liking

I will be giving mx5 mania a call tomorrow and take it in into them, hopefully they may be able to give me a more accurate quote with all those other little bits and pieces that may need to be done, if it is a similar price to one of there second hand gearboxes then i will get them to rebuild it

also i will be keeping my mx5 for a while, i just bought it a month ago and already have the bug, can't stop looking at things i want to buy for it, i never realised how customisable they are till after i bought it

[Regie]

If you are going to the trouble of changing the box, you may as well do the clutch and rear main at the same time. Especially if you plan on owning it for a few years

[zossy1]

I doubt anyone could remove a 6 speed, pull it down, remove both shafts and the relevant gears, buy and supply synchros, refit and rebuild with new bearings, and replace the box for $600. Most shops will charge that much or more for parts and labour just to do a clutch.

Speaking of which, you would surely put a clutch in it at the same time, regardless of which option you choose...

[dzammit85]

Yeah clutch is getting done, though I just wasn't so sure about the gearbox, so I thought I would get people's opinion on that, as the clutch is a easy decision, it's just getting replaced with a exedy heavy duty

[NitroDann]

Yeah the clutch alone is >500 for parts, typically 650.

[chrons_rotary]

I bought my 6-speed for $850 less than 6 months ago, seems to work just as good as the ones people are paying $1200+ for.
Just wait around for the right seller who wont overprice them.

I have rebuilt a RX7 turbo g/box before, not too difficult if you have a press and bearing puller set.
Full rebuild kit was ~$450, don't imagine the MX5 6 speed kit would be too much more.