X box input gear

[Tibout]

Hi guys I'm thinking on replacing my input gear with a cross drill one from Ashcroft before I order anything I wikis like to know how hard is the job going to be? Do I need to just drop the T box and how difficult is it? And also what do I need like bearing gasket etc. I don't have any special tools to remove the bearing will that be an issue?

Thanks for any help and advice

Thierry

[pete3000]

Don't think you have to drop anything out, from memory.

Drain LT230

Remove cover plate (6 bolts)

Remove philips screw/s + pull outer bearing race.

Remove old gear. insert new + replace bearing with diferent shims if necessary.

Re fit cover plate

Fill box back up.

[reb78]

You dont even have to drain it!

The one worry is that if you are fitting new bearings, you should also change the bearing races. The forward race cant be changed with the box in. I think many take a chance and fit a new input gear and bearings and dont change the forward race (i certainly did when i fitted my gkn overdrive). It will still need shimming up properly but you only need a dial gauge for this and a selection of shims. If you are worried about the races (old race with new bearing) and your old bearings are ok, i suppose there is nothing stopping you using the old bearings on the new input gear and this would remove the problem (still need to check shims though).

[Tibout]

Thanks guys so I'll only know if I need new bearing when o remove the input gear? What could be the worst if I use new bearing and the old races? And also how do I verify the shims etc is there any technical data I could look into I have the workshop manual does it include the input gear replacement and how to get the correct adjustment? Sorry for all the questions but I want to make sure I got it right. Just did a conversion and the 200tdi have so much power and smoother than my old TD but every time I'm slowing down when I'm at around 60 mph I could hear the gear making a terrible noise. So I think the input gear is badly worn.

Thanks very much again

thierry

[white90]

You can remove the outer race(within the box itself)if you drain the box and remove the lower cover with a pry bar and CARE

No shims nothing!

remove PTO cover withdraw old gear (replace bearings as you see fit)

replace gear(ensuring it is full seated), replace cover. refit lower cover if you decide to replace outer race(within the T box) refill if you drained it and drive off.

[reb78]

Tony, is it easy to press the new forward race back in place with the box in situ and input shaft in the way? - this would save a lot of time and allow the job to be done properly!

[Aragorn]

The old race welded to a piece of tube would probably work quite well to drive the front race back in?

The box will need reshimmed to do the job properly though.

[Tibout]

hey tony thanks for the reply. just to clarify which lower cover do you mean. what i understand from your advice is that i'll be able to replace the track bearing as well with the box in situ and i don't need shim or anything? hope i got it right

thanks a mil

thierry

[Aragorn]

Not reshimming the bearing is akin to fitting headbolts without a torque wrench.

Ie it might work, but it also might throw its guts over the road and you'll be doing the job again.

[Tibout]

so if i understand:

1. drain the box

2. remove the pto cover

3. get the input gear out

4. put the new one in with new bearing (if need to)

5. put cover back (is there a gasket here to be replace?)

6. re-fill box and that should be it?

[reb78]

I think Tony meant the bottom cover and not to put shims behind the forward race (where i dont think there are any normally anyway). You will still need to shim up by adjusting the ones behind the race in the rear bearing carrier.

Old race on a tube may well work as Aragorn suggests...

[white90]

No tube required it presses in very easily as the box is Alloy unlike a wheel bearing race

I have done this job twice on different cars and never had a noise, howl or any overheating

no Shims required as there are none on the I/P gear inside the box.

The lower cover is the one on the base of the t-box held on with 10mm bolts. oblong shape

Aragorn you are a Doom monger-er.

what are you saying needs shimming?

I have had an underdrive that bolts straight on as do all underdrives, overdrives no shimming required then removed and refitted a brand new I/P gear no issues again used original bearing carrier and cover.

[Tibout]

i'm a bit confused . what if i replace the bearing both ends but only the track bearing on the pto side and use the old shim which is already there? will that make it worst not replacing the other track bearing with new bearing? but i guess if when taking it apart and found that my old bearing are in good condition that will be much easier( but by the sound of it i might have to replace the bearing as well and i've order them to anyway). whats the normal clearence allow anyway when shimming?

[white90]

There are no shims on the I/P gear inside the box if the outer bearing carrier is not marked

it is less than Ideal but no a show stopper to reuse it.

I would replace it as the job is a simple one to complete.

[Tibout]

I was just looking at the tech archive and i have a better idea now . so basically i'll remove the bottom cover and pto cover remove the old I/P gear i think i might get access to the other bearing track with a pry bar and fit the new one without any major trouble (hopefully). thanks again for everyone for your help i'll tackle the job during the w-end if i'm stuck i'll let you know

beat regards

thierry

[Aragorn]

Well there were certainly a shim in the LT230 i took apart and the manual for the LT230 details how to measure and select the correct shim when rebuilding the box.

It sits behind the rear bearing race, between the race and the alloy carrier.

The clearance is -0.05mm, ie 0.05mm of preload on the bearings.

As i said above, it might work fine. Or it might last 5 miles before spitting itself all over the road, depending on how far out the clearance is. If its too tight you'll cook the bearings, and too slack and it'll probably chew up the gears from moving about so much.

From the manual:

NOTE: Shims are available from 3.15 to 4.00 mm (0.12 to 0.16 in) thickness rising in increments of 0.05 mm (0.002 in).

[Marco]

Over the weekend I've assembled two complete LT230 boxes, I recommend to take the box out vs just putting a new gear in. First without taking out the box you can not properly inspect main shaft splines and second checking bearing end float / resistance is not possible with the box in situation. Removing the outer race of the front bearing will be a difficult one... not sure if that's possible at all without removing the box. And when you have it on the shelve it's much easier to check the rest like intermediate shaft (leaks) front + rear output shaft bearings etc. OK it's more work but guess bit more durable than just putting in a cross drilled gear.

Drilling your old gear on a DIY base is also possible, as far as I can compare the only difference is a hole in it! That will save you cash and problems with bearings and alignment.

Beware, by now I know that (new) input gears do not always line up properly, it can easily be one mm off.

Cheers

Marco

[TheHarv]

I have mine in pieces on the bench right now and I drifted the front bearing track out last night - I'm impressed anyone could pry it out through the lower cover, although there are a couple of voids below the track where you could get a tool/puller in only one of them will be get-at-able. I'm a wuss about prying on alloy housings anyway.

I'm no expert but my take would be EITHER take the box off (it's really not many more bolts than the bottom cover - just the 6 or 7 bolts to the mainbox plus the props) and do it by the book OR if the bearings look OK swap the old cones onto the new gear and leave the old tracks/shimming in place

Here's a page I came across with some pics and discussion - it has a link to a small portion of the overhaul manual (covering just the i/p gear fitting and setup) but you can find the whole thing in the usual places

http://www.geoffrey-...nsfer/index.htm

Good luck

[Tibout]

thanks for that lads i'm not going to tackle the job for another week so any advice is more than wellcome

thierry

[nickwilliams]

I think the need for 're-shimming' the LT230 if you change the bearings is over stated.

The shims are required to compensate for differences in the machining of the alloy case, but once the shims have been selected during original manufacture, unless you change the case parts I don't see why re-shimming is necessary at all. Any replacement bearings or other steel parts will be machined to tolerances which are at least an order of magnitude better than you can measure in any normal home or motor vehicle repair workshop, so unless you swap any of the alloy parts there is nothing to be gained by messing around with shims.

As for re-shimmng the input gear bearing, the mounting plate which provides the pre-load on this bearing is separated from the gearbox case by a fibre gasket. There is therefore absolutely no point in messing about with shims to tolerances of .05mm when a difference in torque of a few NM on the mounting bolts for the bearing carrier will squash the gasket by more than this.

Incorrect shimming will not cause the box to disintegrate after 5 miles. If the shims are too small so the bearings are loose the box will probably be noisy (rattly) and if they are too tight it will get hot and whine. Either way, the life of the box will still be at least several thousand miles.

The LT230 is not a piece of high precision engineering. From new a box can last for 100,000 or more miles before they need to be replaced and you can bet that the tolerances on the bearings are nowhere near +/- 0.05mm near when it's done that sort of milage, yet they rarely (if ever) fail catastrophically.

Nick.

[reb78]

If you press a new set of bearings onto a new input gear, they could be quite a way out in terms of the magnitude of difference in the shims. That is why you ought to do it for new bearings and gears.

[Aragorn]

Well for starters only early boxes have the gasket, and the manual specifies the cover must be fitted with the gasket and the coverplate torqued up before measuring the end float.

Later boxes dont have a gasket at all, just RTV sealant.

Fair enough, if the shimming is based on the alloy case, but you dont know that for sure?

The TD5 wheel bearings have a range of shims, and everything in there is machined steel. Theres no guarantee the new cross drilled gear will be the same size as the old one.

I've seen wheel bearings that have welded themselves to stub axles because they've been overtightened, so you cant really just say they'll only get hot and whine...

If your going to the effort of doing a job, its my opinion it should be done properly. Dont do it properly and you'll just end up under the truck again doing the job again. If you want to bodge it up, then fine, but dont try to claim thats the right way to do it.

[nickwilliams]

If you press a new set of bearings onto a new input gear, they could be quite a way out in terms of the magnitude of difference in the shims. That is why you ought to do it for new bearings and gears.

I don't agree. If all you do is change the bearings and you find the shims need to be changed then either the gears are worn to the point where they need to be replaced or you have not got the parts together properly.

[nickwilliams]

Well for starters...

<SNIP>

Next time you do this job then, tell us what the old and the new shims were.

[reb78]

I don't agree. If all you do is change the bearings and you find the shims need to be changed then either the gears are worn to the point where they need to be replaced or you have not got the parts together properly.

Well, thats up to you, but if when comparing the originally fitted gear and bearing, there is 0.25mm difference in the casting of the gear and the same in the casting of the bearing (which is pressed onto the input gear - more room for error here too), that is potentially 0.5mm too much or too little transferred to the position of the bearing and needs correcting with shims - that is what they are there for. I agree with aragorn - it hardly takes a lot of time to do the job properly and in doing so will give you a box that should be reliable in service. Shimming it up is a PITA, but it is there for a reason.

To the OP, the detail is all in the re-build manual (see attached PDF)

LT230T_Transfer_Box_Overhaul_Manual.pdf