MKIII Trans Rebuild Questions

Trying to put the finishing touches on a MKIII tranny rebuild and have ended up with 2 lingering issues.

1) I am questioning an oring for the Ratchet Shaft. Check out Part 19 in Group 7 (04-0079 ORing shift ratchet shaft). I don’t remember taking one off there (of course that's not too surprising) and although there is grooved section toward the base of this part where I guess it may seat, it's OD is alot bigger than the earlier boxes and the ORing ID seems awful small. Is this Oring supposed be there or is it an error in the parts diagram? If its supposed to be there, what's it for? It kinda sits under the ratchet plate - does it dampen the plate action or something???

2) In the parts diagram for the same Group on the Old Britts web site, they've drawn in a couple of parts for the plunger seal which I think were omitted from the diagram originally. See Parts 39 and 40 (06-3447 and 52-390015). The Oring looks correct to me and matches what I removed. The washer doesn't.

I pulled off a pretty thin washer, however the one Old Britts is recommending is thicker and has a smaller OD.

Original: OD ~1.00, ID ~0.63, Thickness ~0.025
Old Britts: OD 0.877, ID 0.628, Thickness 0.050

Mine was pretty beat up, so the measurements kinda varied. According to the parts diagrams, looks like the plunger had no seal or washer in earlier boxes - how did that keep the oil in? Wasn't this gearbox produced this way for years? Anyway I'm confused...

What say the collective hive mind about this? Thanks!

napanorton said:

1) I am questioning an oring for the Ratchet Shaft. Check out Part 19 in Group 7 (04-0079 ORing shift ratchet shaft). I don’t remember taking one off there (of course that's not too surprising) and although there is grooved section toward the base of this part where I guess it may seat, it's OD is alot bigger than the earlier boxes and the ORing ID seems awful small. Is this Oring supposed be there or is it an error in the parts diagram? If its supposed to be there, what's it for? It kinda sits under the ratchet plate - does it dampen the plate action or something???

Click to expand...

According to the 'Amendments' page of my MkIII paper copy parts book:

"[Group]7, [Item No.]19.....04-0079......Deleted - Not Required"

Click to expand...

napanorton said:

2) In the parts diagram for the same Group on the Old Britts web site, they've drawn in a couple of parts for the plunger seal which I think were omitted from the diagram originally. See Parts 39 and 40 (06-3447 and 52-390015). The Oring looks correct to me and matches what I removed. The washer doesn't.

I pulled off a pretty thin washer, however the one Old Britts is recommending is thicker and has a smaller OD.

Original: OD ~1.00, ID ~0.63, Thickness ~0.025
Old Britts: OD 0.877, ID 0.628, Thickness 0.050

Click to expand...

My MkIII also appears to have a thin washer of around the same thickness as the one you found. According to the AN website, the washer is 066622.
http://www.nortonmotors.de/ANIL/Norton% ... 07&Part=39

According to the RGM list, 066622 is a: 5/8" Dished Spring Thrust Washer.
http://www.rgmnorton.co.uk/buy/5-8-dish ... r_3732.htm

napanorton said:

According to the parts diagrams, looks like the plunger had no seal or washer in earlier boxes - how did that keep the oil in? Wasn't this gearbox produced this way for years?

Click to expand...

Yes, only the MkIII indent plunger bolt has the O-ring and washer, presumably if the earlier type leaks then sealant can be applied to the thread.

LAB - Thanks! I'll chuck the ORing supplied in the RGM MKIII kit. As for the washer per the RGM list "a spring washer" doesn't sound like what I have either. At least not how I think of a spring washer. I guess I need to keep looking... You have any ideas? I can't be the first person to run across this.

napanorton said:

As for the washer per the RGM list "a spring washer" doesn't sound like what I have either. At least not how I think of a spring washer.

Click to expand...

They describe it as being like a Belleville washer, so a slightly dished 'spring' washer as opposed to a 'coil' spring washer:

http://www.bellevillesprings.com/bellev ... shers.html

Belleville washers are a more economical and less precise form of conical disc spring, best used for static applications where some setting and/or loss of force can be tolerated.

Click to expand...