Cost of rebuilding NA8 5 speed gearbox?

[ericson]

Hi guys,

About 3 weeks ago took ownership of 1996 1.8L NA which it has been my daily ever since.

One thing I always do whenever I put the car in 1st gear is I keep pressure towards 10 o'clock direction (ie. I move the shifter into 1st and keep holding it with a bit of pressure), because if I don't, when I release clutch sometimes the gear pops out of 1st accompanied by grinding noise. My guess is the shift fork shaft is bent causing the selector fork to not fully engage in gear and when under load (as I release the clutch) it pops out of gear.

Because of this, I avoid using handbrake to assist in starting in a steep hill (even though I want to sometimes) or go into a corner from stand-still without taking pressure off 1st gear as I am "worried" that the gear will pop out.

I also noticed that sometimes I feel two "notches" when putting into 1st, while at times I feel no notches/stops/resistance and shfiter simply goes straight in especially when I put the gear into 2nd first from neutral then to 1st (ie. N > 2 > 1) before taking off from a stop. Not sure if this is normal?

Just wondering if any of you have rebuilt the gearbox or know the approximate cost of having the gearbox fully rebuilt as I'm driving the car daily (consciously worried about gear popping out of 1st and keeping pressure on the shifter is getting annoying) and I plan to take the car to skidpan in the future.

Cheers,
Eric

[manga_blue]

It's usually cheaper and easier to buy another gearbox. Any NA6, NA8 or NB8A gearbox is a direct swap. If it's NB8A then you'll need an NB8A gear lever as well. Condition is more important than which model.

[hks_kansei]

As above, usually a secondhand one is cheaper than a rebuild.

My gfs old work used to charge about $2,000 to rebuild an MGB 4 speed, can't remember if that was regular or overdrive.

But yeah, an mx5 box would be similar labour.

[93_Clubman]

Yeah, $2k-$2.5k has been quoted to forumites over the last few years.

at times I feel no notches/stops/resistance and shfiter simply goes straight in especially when I put the gear into 2nd first from neutral then to 1st (ie. N > 2 > 1) before taking off from a stop. Not sure if this is normal?

Normally the MX5 5 speed GB is very good & reliable in standard or modestly modified MX5s. That technique reminds me of what we used to do with the older Alfa 5 speed GB. Before replacing the GB have a quick look in the top turret for oil & condition of components, but it sounds more terminal. Btw, clutch thrust & pilot/spigot bearings are probably also on the way out if original.

[ericson]

Ouch, 2k-2.5k is more than I first imagined and looks like a 2nd hand gearbox is the way to go. Thanks for the tip on NA6 and NB8A gearbox being a direct bolt on. Currently in process of organising a method of delivery with the seller and a mechanic to have it installed.

Before replacing the GB have a quick look in the top turret for oil & condition of components, but it sounds more terminal. Btw, clutch thrust & pilot/spigot bearings are probably also on the way out if original.

I will take a look under the turret anyway as it's the only fluid I haven't looked and replaced since I got the car.

[hks_kansei]

For future reference, and future gearbox, the oil in the box (note: separate to turret) is supposed to be changed every 80,000km off the top of my head.

[hks_kansei]

Also, if you're in Melbourne I may be interested in buying the broken gearbox once you've removed it.

(Price depending)

[manga_blue]

You beat me to it, only I'm in south coast NSW. I've got a good NA8 5 speed with the 3/4 selectors bent, just waiting for a donor box like that.

[hks_kansei]

Similar here.

2nd has been whining in my box for a few years now, so I know it's a matter of time before I have a 4 speed.

Granted, there are already a few spare boxes in the shed. 2 mx5 5 speeds, plus an auto.
And a pair of Holden 3 speed manuals.

Unfortunately both the 5 speeds are meh, one stripped 3rd, the other has loud bearing whine.

[ericson]

I'm in NSW, not sure how soon I'll have the gearbox replaced but will post updates as things progress.

[ericson]

Just an update. Got the gearbox swapped for around $600 including labour. Also got flywheel resurfaced, installed new pressure plate and clutch. The difference in shifting night and day The old gearbox is left at the mechanic's shop, waiting for someone who needs a donor gearbox for parts.

[Mr Morlock]

$600 for the gearbox and the labour to remove and refit a gearbox seems like a very cheap solution- you would think it would be 4-5 hours labour at least- and what extra for new clutch etc .It underlines that not many people are going to shell out serious money to have the things rebuilt.

[rascal]

$600 for the gearbox and the labour to remove and refit a gearbox seems like a very cheap solution- you would think it would be 4-5 hours labour at least- and what extra for new clutch etc .It underlines that not many people are going to shell out serious money to have the things rebuilt.

MM, think you'll find the $600 was just for labour to install it.

...and looks like a 2nd hand gearbox is the way to go. Currently in process of organising a method of delivery with the seller and a mechanic to have it installed.

[madjak]

5 speed boxes are really easy to pull apart and reassemble. You need some different sized punches, a hammer and a socket set but thats about it. To change a shift fork would take a couple of hours.

The 6 speeds are far harder.

[Blackmx52807]

Neat Gearbox in Adelaide do boxes, mine was shot peened, polished, bearings and synchros, around 2 grand mark for the NA 5spd with you dropping box off