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19,520 Posts
How to: Align your gearbox and PPF / Fix gearbox lash

Please read this guide in its entirety before picking up any spanners. Skipping ahead or rushing could cause you problems further down the line.
This guide is applicable for all models of Mk1 and Mk2/2.5 MX-5s

When does it need doing?
Every-time the Gearbox is detached from the PPF i.e. clutch change, differential change, gearbox change etc.

What do I need?
Breaker bar, 6 sided 17mm + 15mm 6 sided socket(s), trolley jack, a decent length straight edge i.e. a 1 metre length spirit level works well.

Raise the car high enough so you can get under it, preferably on flat ground, then loosen the two PPF to differential bolts, and the gearbox to PPF bolts

How do I do it?

Torque the two 17mm bolts on the gearbox to 104 - 124Nm (77 - 91ft/lb).

Raise the gearbox at the tail end with the use of the trolley jack, you need to measure a distance of 66.0mm +/- 5mm. This is between the bottom of the PPF and a straight edge that is placed on the chassis rails (see picture below).

Torque the the two 17mm bolts on the differential to 104 - 124 Nm (77 - 91ft/lb).

Torque up the gearbox/PPF angled bracket. First torque the 17mm bolt to 104 - 124Nm (77 - 91ft/lb).

Then torque the smaller bolts to 36 - 54Nm (27 - 40 ft/lb)

(Yes I know the sequence numbers are out, but the service manual assumes the box is aligned and to torque up and then measure, I've skipped out the initial torquing bit as we know the alignment is out!)

17 Posts
Brilliant post. I can't see the pictures. It says permission denied. Does anyone know where (or how) I can get them?

Also does anyone know if having the ppf mal-aligned cause difficulty in selecting 1st gear and reverse?


20 Posts
Resurrecting just to keep stuff in the same place.

I'm guessing this was one of the images that you can't see:


Below is the NC 6-speed PPF spec.
30.7mm +/- 4mm, but see note about +15mm for any deterioration.

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