Lewis Posted April 27, 2015 Share Posted April 27, 2015 Talk to me about cross drilled input gears, what do I need to know, where do I get one, and how much hassle are they to fit? My 90 is from 1986 and the drive take up is a bit clunky, so I thought it was about time I tried to sort it Quote Link to comment Share on other sites More sharing options...
Les Henson Posted April 27, 2015 Share Posted April 27, 2015 Might be too late as not only the gear wears, but the shaft as well. Poor lubrication is the culprit - hence the cross drilling to prevent excessive wear. Available from most L/R stockists as far as I'm aware, and not difficult to do. PTO cover and bearing track off, then manipulate the gear off of the shaft. You'll need to buy the 2 bearings as well. Count the teeth as well, as I believe there are two types. Les. Quote Link to comment Share on other sites More sharing options...
Anderzander Posted April 27, 2015 Share Posted April 27, 2015 I got one and for mine and seem to remember the types were detailed on the Ashcroft web site. Quote Link to comment Share on other sites More sharing options...
Maverik Posted April 27, 2015 Share Posted April 27, 2015 http://www.ebay.co.uk/itm/Defender-Discovery-LT230-Transfer-Box-Input-Gear-With-Bearings-26T-FTC4962-/321607212254?pt=LH_DefaultDomain_3&hash=item4ae1489cde See the holes in the middle of the shaft... that's the "cross drilled" bit... Quote Link to comment Share on other sites More sharing options...
reb78 Posted April 27, 2015 Share Posted April 27, 2015 How important is measuring and resetting preload when putting a cross drilled gear into an existing box? In reality, are most ok if you fit it and bolt the old carrier up without worrying about the preloads too much? Reason I ask is that I have two cross drilled gears that match two boxes that I have. I run an overdrive on the box currently in place so don't use either input gear, but could keep one as a spare and offer the other to Lewis. That is, if it isn't better to keep them paired to their respective boxes in the event I remove the overdrive. Quote Link to comment Share on other sites More sharing options...
Anderzander Posted April 27, 2015 Share Posted April 27, 2015 I had this conversation with James - I measured the non cross drilled gear I've taken out and the replacement gear - bearings too and it seems dead on the same. My assumption was thus that the preload variation is in the box rather than the gear - so I think the same shim for the same box is fine. It only my assumptions though. Quote Link to comment Share on other sites More sharing options...
reb78 Posted April 27, 2015 Share Posted April 27, 2015 I had this conversation with James - I measured the non cross drilled gear I've taken out and the replacement gear - bearings too and it seems dead on the same. My assumption was thus that the preload variation is in the box rather than the gear - so I think the same shim for the same box is fine. It only my assumptions though. Yep - i suppose that's fair enough if the gear measurement is dead on as you say. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted April 27, 2015 Share Posted April 27, 2015 I would go with it being the cases too. The gears are ground, and it'll be much easier to keep tight tolerances on that, than on the aluminium castings of the casings and the covers that bolt up to them. Quote Link to comment Share on other sites More sharing options...
Lewis Posted April 27, 2015 Author Share Posted April 27, 2015 Thanks for the responses guys I get that that it could well be too late for the mainshaft, but going on cwazywabbit's replys on this thread http://forums.lr4x4.com/index.php?showtopic=76480 I'm hoping a new input gear will improve things for a while - if mine does 12000 miles that'll last me nearly ten years at present usage Quote Link to comment Share on other sites More sharing options...
dailysleaze Posted April 27, 2015 Share Posted April 27, 2015 Can you get away with leaving the existing bearing track at the far end next to the gearbox? Presumably it would be taking the box off to replace that? Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted April 27, 2015 Share Posted April 27, 2015 Can you get away with leaving the existing bearing track at the far end next to the gearbox? Presumably it would be taking the box off to replace that? If you can get the corresponding race off the old input gear off intact and transfer it onto the new one then yes, you can. What you can't do is fit a new inner race to the new gear but leave the old race in the back of the housing, it will fail quickly if you do. When Cwazywabbit and I did mine a couple of years ago we dropped the box off, not a difficult job but a bit time consuming! As above the preload is determined by the machining of the ali casing so 99% you will use the same shim on assembly. But being a pedant I would still check to make sure, the process for this is in the workshop manual. Remember that if your bearing carrier plate is fitted to the main casing with a gasket it needs to go back on with one, and vice versa. Fitting a gasket where there wasn't one before will reduce the preload and omitting one will increase it. Earlier boxes had gaskets, later ones just used RTV. Quote Link to comment Share on other sites More sharing options...
Anderzander Posted April 27, 2015 Share Posted April 27, 2015 Oops - I never thought about the gasket / RTV and it's so long since I pulled the box to bits that I can't remember which it was. Though it's a RRC box - so likely to be a gasket. Needs a membership on Aulro - but a thread on the preload here: http://www.aulro.com/afvb/1786903-post42.html Quote Link to comment Share on other sites More sharing options...
Anderzander Posted April 27, 2015 Share Posted April 27, 2015 The LT230 manual says the gasket is present up to serial no. 288709E Anyone have the part number for the gasket please ? Quote Link to comment Share on other sites More sharing options...
reb78 Posted April 27, 2015 Share Posted April 27, 2015 Can you get away with leaving the existing bearing track at the far end next to the gearbox? Presumably it would be taking the box off to replace that? I have changed the bearing but not the race in the past. It's not best practice as James says, but it didn't actually cause any issues. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted April 27, 2015 Share Posted April 27, 2015 I have changed the bearing but not the race in the past. It's not best practice as James says, but it didn't actually cause any issues. I know of someone who did that with a wheel bearing and didn't get very far, I know it's slightly different but I think I'd only do it in an emergency tbh. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted April 27, 2015 Share Posted April 27, 2015 Thanks for the responses guys I get that that it could well be too late for the mainshaft, but going on cwazywabbit's replys on this thread http://forums.lr4x4.com/index.php?showtopic=76480 I'm hoping a new input gear will improve things for a while - if mine does 12000 miles that'll last me nearly ten years at present usage Pull your existing input gear out through the inspection/pto cover on the LT230 and make sure there is an unworn area on the splines (there will be on an R380 but I'm not sure on an LT77). If there is then you can go the cross drilled route, if not then it'll be time to change the gearbox output shaft. Pulling the gear to check the splines is really quick. Quote Link to comment Share on other sites More sharing options...
Boydie Posted April 27, 2015 Share Posted April 27, 2015 Regarding Pre-load on the transfer box input shaft. If you replace the existing bearings with items of the same make and refit the same shims, cover gaskets etc. then you shouldn't have too many worries. Taking measurements with a Vernier gauge isn't a bad move to ensure that your new bearing has been pressed onto the shaft in the exact same location as the old worn bearing, if the new bearing is slightly thinner - as in you're going to go from a Japanese bearing to a Timken then this is essential as the difference will need to be made up with an additional shim behind the outer race. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted April 28, 2015 Share Posted April 28, 2015 make sure there is an unworn area on the splines (there will be on an R380 but I'm not sure on an LT77). If there is then you can go the cross drilled route, if not then it'll be time to change the gearbox output shaft. Pulling the gear to check the splines is really quick. No there isn't tried it on mine before we fitted it...it's seemed to be much tighter by feel, fitted everything up and it still bangs and crashes on the road....bit annoyed to say the least, bloody rip off dumb schmuck pirate 4x4 breakers for you..... Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted April 28, 2015 Share Posted April 28, 2015 So it's an R380 only fix then Ed? Or are there cross drilled input gears with short splines as well as the ones with longer splines? Quote Link to comment Share on other sites More sharing options...
Lewis Posted April 28, 2015 Author Share Posted April 28, 2015 So it's an R380 only fix then Ed? Or are there cross drilled input gears with short splines as well as the ones with longer splines? It seems there are input gears with shorter splines - there is a thread by robertspark discussing getting an input gear re-splined to suit a different gearbox where he mentions buying a cross drilled gear to get a longer spline, but it turns out to be the same as the one removed Quote Link to comment Share on other sites More sharing options...
Anderzander Posted April 28, 2015 Share Posted April 28, 2015 The input gear I removed had shorter splines than the cross drilled one I got to replace it - I wondered what that was about. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted April 28, 2015 Share Posted April 28, 2015 So it's an R380 only fix then Ed? Or are there cross drilled input gears with short splines as well as the ones with longer splines? I think so, certainly didn't work for my LT....only think I haven't yet checked is whether the disco output shaft has longer splines, but from memory it hasn't. I was really quite optimistic when I tried it by hand.....no such luck though...banging and crashing like a good 'un.....gearbox rebuild will be required...and that after it was sold to me as a good quality box with splines in good condition.... Quote Link to comment Share on other sites More sharing options...
Boydie Posted April 28, 2015 Share Posted April 28, 2015 Yes, when I went to the local wreakers to obtain a "spare" gear to cross drill it they had several input gears on the shelf, and some did have shorter splines so there are definitely two types - I selected the best of the longer splined units. Quote Link to comment Share on other sites More sharing options...
Lewis Posted April 29, 2015 Author Share Posted April 29, 2015 According to this ebay Ad there are two lengths of 26tooth input gear http://pages.ebay.com/link/?nav=item.view&alt=web&id=220423759679 Quote Link to comment Share on other sites More sharing options...
Hazza Posted April 29, 2015 Share Posted April 29, 2015 My lt77 equipped 110 had no unused splines, they had worn the whole way along. I have tried a cheap quick fix but will keep this to myself until I've got a few more miles on it. Quote Link to comment Share on other sites More sharing options...
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