Looking for someone to shed light on my 1800S transmission
 

Following is the image of my Volvo’s birth certificate, one of Karl's website where it states that both M40 and M41 were installed in P180's, one of the transmission ID Plate showing it is p/n 254409, yet the Parts Book doesn't seem to show it specifically by part number and finally the gear box itself showing it is in fact the M41 casting(fill plug higher on side) not the M40(fill plug lower on side).

Other owners have shown me tags that say M41 with this same p/n so what models have compatible parts to replace #28 in my case?

My question comes out of needing to replace the train of four gears because two teeth on the second gear are missing, well not so much missing as not where they belong since they are laying on the garage floor after draining the oil!

I'd post a 12 sec video if I could figure out how to do it.

gearboxes
 

Hi,
Not knowing much about the part numbers, i thought the figure of 8 part of the gearbox filler plug was;
1 fit the plug in the lower point of the fig8 for M40 non od units.
2 fit the plug in the higher part for M41 with od to allow for a bigger capacity of oil.
I have never seen an M40 case with the higher part for the filler plug.
Back in 2010 i had my unit rebuilt using the best parts from several g/boxes. I have kept the remaining dismantled items so some parts may be good and some may be defective. I noted the gearbox Fab and Part numbers which were dismantled.
1 of them was Fab 317208 part no 254409. Has your 2nd gear got 2 teeth together missing? How does its mating gear look?
I was going to invite you to bring your items for a comparison, until i realised you are near Vancouver. If you are interested and can post pictures of your damaged items i will take a look for you. If you can find new items, great, if you are stuck come back to me.
Chris.

https://www.dropbox.com/s/4z281z45sc..._6505.MOV?dl=0
Give this link a try to see the video of the gear teeth damage, to my eye the mating gears appear fine.

"I have never seen an M40 case with the higher part for the filler plug."

Exactly, but for some reason my gearbox is tagged M40! I've sent this question to Volvo archives to see if they can explain as there records indicate the 18345 Type designation as an 1800(18) with overdrive(3) for the N American market(4) having a M41 gearbox(5).

I haven't torn the thing apart yet, just looking down with the shifter cover removed as when I drained it of oil one tooth dropped out and then after opening the top cover and laying it on its side a second tooth dropped out. The mating gear is easy to look at and doesn't appear damaged.

What I do know is the second gear with the teeth missing had 20 teeth.

Gearbox issues
 

Hi,
Tried to open pictures though I cannot view without subscribing to dropbox. Sorry.Chris

A LOT can happen to a car in 60 years , someone must have fitted that gearbox to replace the original ...

The basic M40 can be converted for overdrive use by swapping in the longer main shaft. Yes it will have the level plug in the wrong position but if you drain the box completely and then add the correct amount of oil from the top that is fine. If your box turns out to be leaky best to fix that as being sure of the level then becomes difficult. I have had an Amazon with this type of converted box. The conversion of it was documented in the Driver a few years ago. Done by John Smith and Nigel Ayling. It worked just fine.
Playing devils advocate here, and asking if someone can post a pic of a gearbox plate that actually has M41 stamped on it.

JG I think that you will be able to replace your broken gear with a good one from any M40/41 box. I haven't checked the parts book but I think they are the same. I shouldn't make for a noisy box, that is invariably down to bad bearings.

“I think that you will be able to replace your broken gear with a good one from any M40/41 box”

Derek, that is reassuring. Thanks

“ A LOT can happen to a car in 60 years , someone must have fitted that gearbox to replace the original ...”

Clan, as you should be able to see by the Volvo documentation and the identity plate the transmission in my car is factory installed, it’s not a replacement.

gearbox
 

Hi,
This evening I have had a look at the gears in my oily box of parts. 1 mainshaft is still complete, the rest are dismantled. Looking at the parts removed from the mainshaft I put matching individual gears together. Counting the teeth, the only items with 22 teeth is the smallest gear. According to the Haynes manual "3rd gear is easily identified because it is the smallest gear"
Anyway i visually found 1 only difference between the 2 gears with 22 teeth.
1 has an inner removeable cage with needle roller bearings.
The other has an inner sleeve with holes in it to allow the oil through. This sleeve must be a machined fit.
I then trial fit the gears on to the shaft and both were a snug fit.
I noted each matching gear pair had the same set up, so I must have the remains from 2 dismantled gearboxes from different years.
I am assuming that the bearing design has at some stage been modified by the gearbox manufacturer. I hope this helps.
Chris.

Hopefully this is making it clear.

It is the "2nd Speed Gear" on the Idler or Countershaft drive gear that is missing its teeth, complete this gear has 20 teeth. It is the gear portion immediately in front of the reverse gear, therefore the third gear on the idler or countershaft from the front.

Is This what your looking for Derek ?