Aug 1, 20196 min read

M32 GEARBOX | Guide To Faults & Fixes

Updated: Apr 13, 2022

A guide to the common faults and repairs including uprating the Vauxhall, Alfa Romeo, Fiat M32 gearbox . If you are unfamiliar with its factory name the M32 gearbox is the common 6 speed gearbox found in most Vauxhalls as well as Alfa Romeo and Fiat.

M32 Gearbox Symptoms

So chances are if you're reading this you either have issues with or have suffered from problems with your M32 transmission. You're not alone and this gearbox has kept Eco Torque very busy over the last few years. In fact we are up to over 1000 repairs or complete replacements on this one particular type of gearbox alone.

As there is so much information and updates with this unit there may be separate standalone guides so be sure to search M32 in the tags and search option to get the full story.

So onto the common symptoms.......

6th Gear Bearing Whine

M32 Gearbox 6th Gear End Bearing Fault — M32 Gearbox 6th Gear End Bearing

By far the most common symptom we have described to us and manifests itself in a loud whining sound mainly in 6th gear.

This is down to the wear in the 5th/6th output shaft bearing and creates a distinct whining sound mainly noticeable in 5th and 6th gear. A common misconception is that 6th gear it self has its own bearing however this bearing along with another supports a whole shaft of gears.

If this issue is left too long it will result in the bearing fully collapsing causing severe damage to the internals and in some cases ejecting metal out of the end casing of the gearbox.

M32 Gearstick Movement

This issue is directly relates to the issue above and stems from wear in the 5th/6th output shaft end bearing.

It results in a downwards movement of the gear stick (towards the centre of the vehicle) in 1st and 5th gear. These gears share the same shaft and it the reason why you see the issue on both gears. At this stage the end bearing is very worn and results in the whole shafts physically moving our of place inside the gearbox. This transmits the movement through the selector forks and out through the linkage into the gear stick. As you can imagine gearboxes are very precise bits of engineering so movement in this way is a very serious matter!

Another common misconception is that people know of the gear stick symptom but notice it in 2nd 4th and 6th and think their gearbox has the fault. This is not the case and is simply engine movement transferring through the linkage.

Watch the video below to see what the gear stick movement symptom looks like.

Constant Bearing Whine From 20 MPH Upwards

M32 Output Shaft Bearing Wear — M32 Gearbox Output Shaft Bearing Wear

This one is less common but often comes to us after being misdiagnosed as a wheel bearing issue. The constant whine starts at 20-25 MPH and is present even if the clutch is depressed. This is due to the fact that the bearing at fault spins with the output shaft and differential, so will ultimately make a sound if the vehicle is in motion. This issue requires a full bearing rebuild to resolve. We have noticed that this can sometimes be a result of incorrect shimming and gearbox oil contamination.

Crunching Or Loss Of Gears

Very common especially in 2nd, 3rd and 4th gear. This starts of with intermittent crunching when selecting gears. This progresses with the crunching becoming constant and then develops to gears "popping out". At this stage the wear on the gear has caused it to lose a proportion of its contact teeth meaning there is simply not enough there to keep the gear engaged. This will ultimately lead to the complete loss of the gear.

This issue can be increased drastically by a worn clutch system and heavy gear changes. The Vauxhall VXR models are more prone to this issue due to the nature of driving style they exhibit.

The pictures below show the worn teeth on the top of the gears

Sloppy & Stiff Gear Selection

This issue is normally the linkage between the gearbox and gear stick rather than an internal issue. It can feel like moving the gear stick through a thick fluid when trying to select gear. This will require the linkage cables being replaced. The issue can also arise from oil contamination, bearing wear and broken selector forks.

M32 Gearbox Oil

Performing a regular M32 oil change will benefit the unit greatly, as this will remove swarf and contamination from the unit increasing the lifespan of the gearbox bearings.

The M32 transmission oil capacity was originally 2.2 litres of 75W 90 gearbox oil, however this can be increased to 2.5 litres on the Gen 1 unit without any issues.

The Gen 2 version with the updated endcase does not necessarily need the increase in oil capacity due to the improved oil flow guides within the casing. Using good quality oil will always help with the lifespan and units with a limited slip differential must use a slightly different grade.

M32 Gearbox Shimming

This is one of the most crucial elements when rebuilding any gearbox, it is almost one of the most overlooked factors. We know that a lot companies offering repairs on M32 transmission and DIY repairers do not check or adjust the shimming in the unit. It is a question normally dodged in the comment section on Youtube tutorials and articles written. We know this because the customers we have come to us that are requiring their third rebuild after only having a set done sometimes less than 20'000 miles previously.

Why is gearbox shimming so important? The shimming sets the bearing tension within the unit and this is essential for any sort of lifespan. Too tight and the increased friction and heat will wear the bearing out too quickly. Too lose and the excessive movement will produce uneven wear and come apart spectacularly.

The shimming must always be checked even if you are not replacing casings! Unfortunately the shimming on the M32 is known to be incorrect even from factory. This is particularly evident in the Vauxhall Insignia gearbox, as the 1.8 models can come in on only 40'000 miles.

We are asked on a daily basis, what shims do I need in my gearbox? Shimming of a gearbox is individual to each unit, it requires the measure of the tension of the shaft and checking of freeplay. It is not something you will find reference to online.

If you are performing the M32 transmission upgrade from the Gen 1 to Gen 2 casing this must be done correctly otherwise it will destroy a new set of bearings very quickly. We know that we will not repair everyone's M32 unit, so if you are reading this and using a local repairer, ask about their shimming process. If they say they don't need changing or they do not sound confident on the subject, then it would be worth finding another repairer. This could save you hundreds of pounds in the long run.

M32 Gearbox Upgrade

As there is so much information on this unit, we have written a separate article on the upgrade from Gen1 to Gen 2 here. It details the difference between the casing and bearing sizes. It also explains the myth with uprated bearings.

How To Indentify My M32 Gearbox?

Vauxhall, as well as the other car manufacturers which have this unit have not made any clear uniform marking for each unit. Units have stickers with barcodes from new, however these are usually lost with a few thousand miles of road use.

Valeo has produced a guide on whether you have and M32 or F40 here.

What Vehicles Have The M32 Transmission?

We see mainly Vauxhall when we repair the M32 gearbox. This is partly due to our geographic location, being based 15 miles from Luton, the home of Vauxhall. However its mainly down to the fact that there are a huge amount of them on the road, spanning numerous models over various years.

Makes and models effected include