Series 3 gearbox rebuild problems

Hi all,

Ive decided to put myself up to my neck and ploughed into stripping a spare gearbox down to rebuild and then replace my noisy current one. So far the transfer box was fine to strip and have the new parts on order, however the main box has been causing headaches and i'm running low on swear words.

I stupidly tried to remove the bell housing without removing the layshaft bolt first (which is on tighter than anything else) and even removed the primary pinion cir-clip and output cir-clip both of which I have replaced now. Through my effort to split the housing from the mainbox I appear to have miss-aligned the gears maybe or something as the box is now locked with reserve and 2nd gear (I think) engaged. The bellhousing also won't meet the mainbox anymore and I don't want to force them.

So, any ideas on how to get it all into neutral again firstly and secondly the best way of removing the layshaft bolt?

undo lay shaft bolt ,failing that remove all bell housing stud and bolts ,selector shafts and try again

jamesmartin said:

undo lay shaft bolt ,failing that remove all bell housing stud and bolts ,selector shafts and try again

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Thanks James, I had the selectors and all that out and it seemed to be the layshaft bolt was the only thing hold it all together since I thought I would just be able to remove it all in one go. Ive reassembled it now and swung off the layshaft bolt with heat to no avail (3rd gear engaged with rope wrapped around the output drive gear). So im either thinking of brining it to a local garage to let them swing off rather than investing in more tools which I dont have the cash for

whack the end of the bolt it will shock it loose eventually and break the loctite hold, a battery or air gun usually shift them

with the selectors out you can manually select two gears which will lock the box up for you.

jamesmartin said:

whack the end of the bolt it will shock it loose eventually and break the loctite hold, a battery or air gun usually shift them

Click to expand...

When you said whack it, should I be using a buffer between the hammer and it or just whack it whatever way? Could I not end up deforming the head of the bolt?

Blackburn, even when I had 2 gears selected the layshaft would turn under the force of myself and a mate trying to get the bolt off.

Also when I reassembled it the bellhousing is now standing proud of the mainbox by maybe 100mm or so. If I try and tighten the bolts the mainshaft locks up put I can still turn it at the output side.

yes hit the head with a large punch and large hammer fit socket before head deforms too much , a new bolt is cheap

I ended up getting the bolt out! Threw more heat on it, penetrating oil, a breaker bar and myself and a mate swung off it and it released! Someone in the past had put some gunk to make sure it was hard to get off. Great feeling getting it off though! Onto rebuilding now

i made that layshaft bolt mistake the first time round too. its easiest to crack that before you take the transfer case off. i made a little bar that locks the front propshaft flange to the transfer lever bracket on the bellhousing. then put in into low ratio and that locks everything up nicely so you can crack the mainshaft nut and layshaft bolt on the bench without much problem.

Dylan353 said:

I ended up getting the bolt out! Threw more heat on it, penetrating oil, a breaker bar and myself and a mate swung off it and it released! Someone in the past had put some gunk to make sure it was hard to get off. Great feeling getting it off though! Onto rebuilding now

Click to expand...

its a good idea to put stud lock on the l/ s bolt they often come loose and cause real problems

jamesmartin said:

its a good idea to put stud lock on the l/ s bolt they often come loose and cause real problems

Click to expand...

Cheers, ill be sure to put some on when its going back together!

So im going through all the parts I need to replace on the gearbox project at the moment and the overhaul kits are probably the way ill go.

Who would ye recommend? Ive seen Synchro Gearboxes kits and Peagasus parts.

i got a couple of kits (main and transfer) last year from shop4autoparts and i am very happy with the quality of them. none of it was any trouble to fit and i have not had a hint of trouble with those parts since.

So I get a little further and hit another wall. Am I right in saying the locating peg on the mainshft should come out with relative ease? Any tips for how to get the thing out without going down the drilling and collapsing route?

Dylan353 said:

So I get a little further and hit another wall. Am I right in saying the locating peg on the mainshft should come out with relative ease? Any tips for how to get the thing out without going down the drilling and collapsing route?

Click to expand...

mole grips or a new shaft ,leave alone unless the thrust washer is broken

jamesmartin said:

mole grips or a new shaft ,leave alone unless the thrust washer is broken

Click to expand...

Thanks as usual James! I'd be tempted to leave it but the bearing at the rear is knackered and I'm under the impression that to replace that bearing I've to remove the 1st and 2nd gear craic?

rear bearing comes off the rear of the shaft ,remove 1st and 2nd gears then push bearing housing to the rear , your left with shaft thrust washer held in place by pin

jamesmartin said:

rear bearing comes off the rear of the shaft ,remove 1st and 2nd gears then push bearing housing to the rear , your left with shaft thrust washer held in place by pin

Click to expand...

Shows what I know! I'll let you know I get on, cheers!

jamesmartin said:

rear bearing comes off the rear of the shaft ,remove 1st and 2nd gears then push bearing housing to the rear , your left with shaft thrust washer held in place by pin

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edit first gear is on the bearing housing side but result is the same they go rear wards,2nd and 3rd come off the front the rest off the rear ,you need a press or copper hammer and support

Well I finally got it apart! Made a mess of the bearing carrier but hey, live and learn. It took two of us with heavy hammers, heat, oil etc to get the thing to shift! On the plus side, the gear, synchro and such were in good nick, however I ended up breaking the locating pin for the thrust washer and drilled it out, how precise must the height of the pin be? Do I just need to get a new mainshaft?