6 replies to this topic

[nz_seamless]

I have fully rebuilt this box, it's a DAM2886 which is very early A+, so bigger input shaft and drop gear shafts, but still an A gearset.

 

I have two issues, first is that when I run the input backwards to the normal direction of rotation, there is no neutral. If I run it normal driven direction I do get a neutral. Is that normal for a rebuilt box? To bind when run in a direction it won't see in normal conditions? It freaked me out because when I had assembled everything and was seating the mainshaft oil seal, I couldn't get the box in a neutral position.

 

Second and more importantly, when shifting into forth, if you pull the gear lever all the way back, it's pushing the syncro too far and it rubs on the laygear. If you push the gearstick back just a little (as though starting to change into third) then you can feel it settle into the proper location. In the video I am pulling back hard, as you would on a normal change into forth, then creeping it forward which you can see settles it about 4mm from its hard over position. 

Should the syncro even be able to move that far? Is it free to move as far as it wants but the rodchange mechanism is expected to only push it far enough? Should I be tearing the gb down to check the syncro hub, or should this be resolved using the rodchange?

 

https://youtu.be/0CtXzFF9S4k

 

[Spider]

The 1st and 3rd (Mainshaft) Nuts torqued up?

 

If yes, then it could be that the bearing sleave under First Gear hasn't seated completely or the mainshaft has hung up on the Mainshaft Bearing. I've found with all the late Mainshafts, they are in interference fit in the Bearings, some ridiculously so, to the point where I've had one new bearing coma apart, just by fitting the shaft. I now grind them all back to size, as the earlier shafts where. This same 'oversize' picks up on the 1st gear bearing sleeve more than it should too.

 

While I haven't found a crook one, it could be worth checking the 3rd / 4th selector fork, the parts of it that fit on to the selector shaft actually set the throw stops, if the end facing the back end of the box (1st motion shaft end) is too short, it will over throw.

Edited by Moke Spider, 02 November 2015 - 09:18 PM.

[nz_seamless]

Yeah everything is torqued up and the shaft is the original one as is the top hat. 

I'm trying to remember but I couldn't have gotten the 3/4 selector fork on around the wrong way could I? I think for memory you won't be able to get to the roll pin hole if you do that, but that does fit the symptoms a bit better.

[Spider]

I think you'd have a pretty hard time trying to get the selector forks in the wrong way around!

 

The issue that you've noted regarding 'Neutral' is usually from a distorted baulk ring or one that's undersize. I have had a few like that, typically Genuine ones, it appears that they get ever so slightly out of shape, I'm not sure if from heat treatment or something being dropped on them.

 

The other thing that could possibly relate to both issues is the big 'C' retaining plate for the Mainshaft Bearing. These often have shims between them and the casing, if any, usually only one or sometimes two. Most times you don't need to fit them (I very very rarely fit them), but if the case was machined such that it needed a bit of shimming and these are not there or not enough, it will push the Mainshaft further down the casing, but we are only talking maybe 0.005". I don't fit these shims 999 times out of 1000 as it's important to lock the Mainshaft bearing as tight as possible in place. I think the workshop manual says up to 0.001" float is OK!     In their dreams maybe,,,,,,,

[nz_seamless]

It does have shims in the mainshaft retainer, but for memory I was using feeler gauges to put a little preload on that bearing as per Haynes. I think I might strip the box completely and go through and check everything again.

[nz_seamless]

Back in bits and nothing looks amiss. Highly frustrating.

[nz_seamless]

And solved. This is a case of looking at something half assembled. When the transfer case is in place it prevents the selector shaft from overthrowing like this, I was seeing issues where there were none if the motor was assembled.

Thanks Moke for the replies