Hello,

I was wondering if someone could tell me which of the two following gearboxes are the strongest. I have a 1967 or so 123 GT with an M41 with overdrive and a 1971 P1800 with the M400 overdrive.

Just curious, cheers for any info.

Regards,

Michael

Sounds like you have looked already, but are you sure the 1800 gearbox is a M410? They only came from Volvo on the 1800 in 1970. Of course any number of things could have happened since then, resulting in an M410 on your '71 1800. But thought I'd deal witht eh easy question first.

--
Justin 70 1800E, 66 122E, 71 145S
Read vclassics!

You're off on your nomenclature. The overdrive in your 1800 is an M410.

The M41 is a more robust unit. It was originally designed for the 164.

The M410 on a B20 is a very rare unit. Only used for a year or so.

So, while the M410 is much stronger, it's weakness is in that it is somewhat rare (relative to the M41) and that some parts can be harder to find.

"The M41 is a more robust unit. It was originally designed for the 164. "

Should read, "The M410 is the more robust..."

That being said, have you ever heard of anyone breaking either one through hard use? They can wear out, of course, but out and out breaking is practically unheard of.

My first car was a 1963 beetle - I broke the tranny 'hockey stick' on an exuberant 1-2 shift. The part was pretty cheap but it took an insane amount of work to replace it...

I have successfully stripped gears on a M41... of course, it still got me down the road, but without first gear...maybe reverse too...don't remember, but the small gear on the layshaft was no longer a gear.

Of course, that was due to a set of bad (missing my then) roller pin bearings in the layshaft followed by first gear clutch dump from redline when I was having a bad day... no fault at all of the gearbox. I have also seen lots of chipped and broken teeth in gears of M40/41.

I would think the M410 would indeed be a beefier unit, but they have the bearing issue... they are all noisy, and if they aren't...they will be soon.

-Matt

Wearing out is highly possible, given that the newest M410 is 28 years old. And the boxes do break under hard use. Racing, I mean.

Hello,

An M410 is MUCH stronger than the M41. However an M41 (the later type with J-type OD) can handle a lot (know a few people that race with these M41 boxes and have well over 170 Din hp without any trouble the last few years)
It is known the M410 gets noisy after a few 10000 miles already but that is caused by a plastic bearing that wears out prematurely, if this is replaced by a bronze bearing the problem will not come back again.

BTW. I am still searching for a bellhousing to mate my M410 to my B20, so if anyone has one for sale let me know.

CU

Stefan

The M410/400 bearing that wears out is PLASTIC?? Is the bronze one the
standard replacement or do you have to have it made?
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma

If I remember correctly it is indeed a sort of plastic bushing that wears out and causes the noise because the axle that runs in it isn't centered like it should.
A friend of mine made the bronze bushing himself on a lathe (about 10 years ago) and installed it in his M410.

CU

Stefan

Sounds like it would certainly simplify the job. If I should happen
to install the spare tranny I have I'll seriously consider the same
operation. Many thanks.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma

George. If you fit phoshor bronze bushings to gearbox machine them for floating fit. Minimum .004" clearance id and od with spiral oilways. Any closer tolerance and they will seize because of lack of running fit for heavy oil. Seized trannys are not easy to dismantle.