H151F manual gearbox rebuild

[Ben Rydz]

P.S. No, no need to use a puller on the outer race. Sorry should have read your question more carefully.

Hi Frank,

Thanks for that that's good news, as the factory manual said to use a puller however it came straight out and the outer race is slightly loose in the intermediate plate, there is maybe 0.25mm wriggle room in it (I'm guessing here as it's not much), and it looks as though it's only just begin to spin, it slides in and out quite easily. The inner plastic race and bearings all appears to be fine and shows no signs of seizing at all.

As I've never rebuilt a gearbox before I wasn't sure if it was meant to be like this or not and was worried I'd have to buy a new intermediate plate. This gives me confidence that it's how it should be.

Another question, my box has a slight crunch into third and on inspection the synchros all appear to be fine as do the keys and hub, I'm going to change these anyway but should I be looking for anything else as a cause of this crunch?

Cheers

Ben

 

[frank rabbets]

The crunch into 3rd may not be cured by new synchros. Mine did it with only 30,000 miles on the clock, together with stiff 2nd gear.

I took this box apart an roughed up the cone on the hubs to make the synchros ring grip better but it made no difference.

Some say using thinner oil will make theses boxes better as the rings will be less slippery. Makes sense but I have not tried it. I just live with mine.

When you put the box back together and have put the bearing circlip on you could wipe it clean with degrease and put a smear of sealer round the circlip/bearing end. This will stop it turning most likely. That is if the bearing is OK.

 

[Ben Rydz]

Thanks Frank, yeah that is my fear. I'll change it anyway and fingers crossed fixes that problem seeing as though it's all apart.

Yeah the bearing is fine, just the casing has moved so I may do like you've suggested or put some bearing locktight.

 

[clivehorridge]

Love this thread.

Sadly, I don't have the confidence to even try this, although I know my gearbox would benefit no end from such treatment.

Beautiful job there and so much essential attention to detail. Looks like the "specialist" has a lot to learn.... as so many do IME.

 

[frank rabbets]

They are a bit of a nightmare Clive. Best to have 2 people to help and double check.

Loctite will do but will make taking the gearbox to bits again just a little bit more difficult as IIRC you can't remove the counter shaft until the outer race has been knocked out of the centre plate.

 

[Ben Rydz]

Yeah that's true but I can pull it out of the plate if need be, but I'm not planning to remove this again anytime soon. I've been given some loctite from a machinist who has used it at times and said this one will hold but not be so strong as to not be able to take it out again. I had him sleeve and machine my input shaft and he also made my flywheel like new again.

Going to purchase the necessary spares today, do a clean down of all the parts and start re-assembly, and fingers crossed when it goes back in it doesn't eat itself to bits!

 

[Neville Manno]

Hi Guys. I am new to this site. Was very interested in the H151 Gearbox rebuild article. I have a HZJ105, with the R151 Gearbox. I have recently purchased a Brand New H150f (I think) from a VDJ79, with the intension of fitting it behind my 1HZ with after market turbo. When the new box arrived, I realized my mistake, being that the VDJ79 has a much longer front input shaft!!!!, so obviously I have to swap the I/P shaft. Does anybody know wether the I/P shaft from a HDJ79 or 100 fit, ie is the Gear the same size, is it still a 14 spline shaft? I have the new 300mm clutch and pressure plate, so I would like to use these!!! Will need some more help later, on the best way to swap these shafts??
Cheers Guys

 

[Geoff Bart]

Hello all,
This a long one but stick with me. See a LOT of experience with the H151F gearbox on these pages. Perhaps someone can help with this query? Current steed is an 80 series petrol Cruiser (1997, 40th Anniversary Edition in OZ) fitted with the 5 speed box in question. Generally the vehicle is in very good condition for age with almost 350,00km on the clock.

Over the last 5,000km has developed a worrying noise in 4th and 5th gear only.........when driving it can be noticed mostly on coast (with power gently oscillating between drive and engine braking). Box shifts beautifully through all gears up and down and does absolutely nothing wrong, ever. The noise is not terrible, just noticeable when driving.

As an aside to a few other comments on previous pages, have used a few different transmission oil types/grades over the years but now run Penrite 75w-85 fully synthetic GL-4 grade manual transmission oil with one small 125ml tube of Nulon G70 "Smooth Shift" which has DRAMATICALLY IMPROVED the gear changes in this cruiser box.

Even when cold, straight into the historically bothersome 2nd gear with no delay, once warmed up almost silky into 2nd. General advice from those in the know is that a GL5 grade oil is neither required or recommended in older manual transmissions as additives, or lack of them, will negatively impact the syncro ring material. (75w-85 synthetic is also plenty strong enough regards EP grade.........its a manual gearbox after all, not a diff coping with huge downstream torque and gear impacts).

Back to issue at hand. Car stationary, Transfer in Neutral, engine at idle speed working through the gears there is a "rumble" in both 4th and 5th. (1st, 2nd, 3rd and reverse, all quiet). Listening under the vehicle it sounds a little like gear wear (lash) but has come on so quickly that I am doubtful of this. More like worn bearings or the like somewhere on the 4th/5th drive train. Also, the noise is still at least evident but quieter with load i.e. increasing engine revs which seems to rule out gear "chatter". Also noise is only evident in 4th/5th so unlikely to be mainshaft or layshaft main bearings?

Have only owned this vehicle for last few years so early. Logbooked for first few years of its life but mid-life maintenance history is unknown, although the "Old Girl" is a good example of the model and generally has been well cared for mechanically over its life. Some mention of perhaps a previous owner "towing in 5th gear" causing undue wear but the noise is in both 4th and 5th so perhaps questionable?

Any ideas?...........loath to pull the box out at this stage as it really is not causing a problem (and clutch is fine so no excuse there) but then again I wouldn't want it to unexpectedly go "BANG" in some inappropriate place on earth a long way from civilisation.

Welcome any suggestions from anyone with similar experiences to offer here or perhaps suggestions on what part(s) may be wearing and their expectant life? Crystal Balls front and centre. Thanks in advance.

 

[Dave2000]

Is the rumble 'rythmatic', (new word), comes and goes (or louder/quieter) at regular intervals?

If so then I would be thinking bearing.

regards

Dave

 

[Geoff Bart]

Hi Dave,

Couldn't really describe it as a "rhythmic" sound nor does it come and go. When driving, it could be classed as a bit of "Zizzy Whine" - mostly when "coasting" but barely noticeable when pulling under load or on downhill with engine braking (i.e goes quieter whenever there is a load on driveline)...........and it is not particularly loud. Many people would not even notice it when driving.

When stopped with transfer case in neutral it sounds like a "rumble" or "gear chatter" under the vehicle when car is idling in 4th or 5th gear. Noise speeds up with engine speed. Like small stones in a bucket of oil being mixed around really quickly.

Perhaps sounds like a large roller ball bearing on the way out but can't understand why it (the noise) is only evident when in 4th or 5th? The larger bearings in the gearbox are in play on the mainshaft and layshaft in all gears (so if it is one of the larger bearings why is the noise not showing up on the other gears???)

All symptoms are only apparent in 4th and 5th gear (no other gears or when box is in neutral) with the noise possibly a little louder when in 5th gear. Maybe its "speed related" and the output shaft is spinning at its fastest in 4th & 5th and the bearing on the output shaft only gets noisy under speed? (Best guess only....)

Regards Geoff.

 

[frank rabbets]

I've heard this rumble on an 80 we changed the 2nd gear synchro on after the box was assembled but the fault must have been there before as it's impossible to put a major component in wrong. I wonder if it is just the oil additive you are using or was it silent straight after the change ?

I would take it for a run and get the gear oil hot then drain it when hot and let the oil settle. If there are metal fragments this may point to the problem but if the oil is clear you will be no further forward and probably none the wiser if you strip the box.

 

[frank rabbets]

More thoughts. The idle rumble and noise in drive on over run may be coming from 2 different causes. Idle rumble is nothing new especially on large boxes. Aston Martin had this problem on new cars back in the 80's when they brought out their monster AM V8 vantage. Customers complained but nothing could be done and there was no fault per se. So in itself the rumble may not be a problem. Easy to obsess about the rumble and equate the two but are you SURE rumble was not there before?

The noise in drive on over run may be coming from a different source. Chris was chasing a noise for over a year which he thought was gearbox but turned out to be worn dif pinion bearings. Again back in the day worn dif pinion bearings would first show themselves on over run in high gears when there would be just the right amount of back torque to produce the sound. Sound travels up the prop shafts and appears to emminate from the box.

Perhaps get both difs and both boxes n hot and drain all oils and inspect for metal swarf. Must be done straight after driving so the bits don't settle to the bottom of the box.

 

[Geoff Bart]

Thanks Frank,

Yes, some very practical suggestions here. Pretty sure it (the noise) is originating somewhere in the gearbox as the symptoms are evident with the vehicle stationary and with transfer case in neutral and gearbox spinning in either 4th or 5th. Rumble noise is worse at idle but it is only evident when vehicle is in either 4th or 5th gear at idle speed.

When the engine is gently sped up, to say 2000 rpm in either 4th or 5th gear, the "rumble" then tends to a rough "Zizzy Whine". No similar symptoms with box in 1st, 2nd, 3rd, reverse or neutral. Honestly can't confirm if the rumble has been there for a long period as only started close examination when unusual noise started to appear while driving in 4th and 5th gear. Its a strange one for sure.

Didn't mention earlier, but had dropped the transmission oil as the logical start to the investigation a day before writing the first post . (Drain was performed as per your advices i.e. oil hot and dropped pretty much immediately after stopping).

The oil in the box had been in there for around 18 months (10,000km) and the vehicle has had quite a few tough days out over the period. Its not routinely a "daily drive", mostly used for 4WD holidays and dirty weekends only.

The transmission sump plug magnet had nothing of note on it when wiped on a white tissue (see attached photo as tissue was still in the garage bin).........minor dark slurry and just a few very tiny metal flakes. Pretty typical deposits I would have thought, all things considered? The drained oil is still sitting in a clean container and I will strain through a fine cloth tonight to see if there was anything of note suspended in it.



Re the Nulon G70 fiction additive mentioned. (https://www.nulon.com.au/products/Specialty_Products/Manual_Gearbox_and_Diff_Treatment).

Have used the product over many years with no problems and can honestly say that it does have a very noticeable and positive effect on rough-shifting. It does however turn the oil a bit "milky looking" because of its creamy texture so can be a little surprising when someone sees the oil draining out and its not the usual honey or clear colour that was put in. Only ever read positive comments and have never heard of anyone associating the G70 additive with any problems (has been in the market for probably close on 20 years now I'd think?). Others on the forum may also have experience with the product?

In the interim, guess I'll just need to keep on with the investigations............

Thanks again. Input is much appreciated. Regards Geoff.

 

[AndycruiserguyLomas]

Easy answer to all this 2nd gear/ rumbling problems. Buy a good second hand box from a Landcruiser 80 series which is badged "Amazon", the one with the dash air bag, or a 100 series manual box and swap the bellhousing and your problems will solved. It will help if you can drive the vehicle first.
I went down this route to overcome the problems I had with a box with a 2nd gear issue, the differences in the boxes is amazing,

 

[frank rabbets]

With no debris in the oil I doubt whether you'll be any wiser stripping the box apart. I understand your tests confirming noises with transfer in neutral off the road. However you may have an identical sounding noise from another component when driving on road and assume it's still the gearbox. The noise in the gearbox may be drowned out by the latter sound. I know you are 100 % convinced the noise is in the gearbox but I have seen and experienced this confusion before so I would check the axle tranny oils for debris.

 

[Dave2000]

I could have sworn my gearbox was making a row a couple of years back, turned out to be the transfer.

No saying this is your issue but as per Franks post, easy to make a mistake.

If the noise is there when stationary then that will discount the axles and prop shafts, so you have at least that comfort.

regards

Dave

 

[Geoff Bart]

Thanks for the various replies. Frank, do agree that with the age of the vehicle and so forth there could well be other parts needing attention in the drive line that are also in play and contributing to noise and vibration while driving. A lot going on with these things being "full-time 4WD".

Dave, definitely the transfer case is still in the frame and wondering whether the "rumble" when stationary might be the drive from gearbox output to the transfer and only evident at faster speed (4th/5th gear revs)? The vehicle does have a VERY VERY slight (but not usual) transfer "whine" at highway speed that is pretty much normal for any Cruiser with these miles on the clock. Certainly not worried about that. The Series 2 Landrovers were notorious for it and the things just went forever!!

Strained the dumped transmission oil this morning (that had been sitting for two days) and it was fine. Absolutely no foreign bodies, metal residue or anything else untoward in it. Would have happily put it back in if I had not already refilled with new oil. There could of course be something safely contained in the internal oil strainer/filter but that is as good as Pandora's Box until the gearbox is ultimately in bits on the work bench.

Will drain and change the oil on the transfer box as a final step just to be confident that I've done all I can (without pulling the gearbox/transfer out for inspection). I suspect Frank will be correct that even on removal and disassembly there is every likelihood that nothing will be particularly evident as the gearbox continues to perform flawlessly.

At this stage, while it doesn't point to being a "terminal diagnosis" I'll keep on as usual until something rears its head and points more clearly to the underlying problem.

Thanks again to all for your individual thoughts on this one. Regards Geoff.

 

[Jon Wildsmith]

just a thought about it being bearing noise - when the gear is selected the hub is locked to the gear so the hub bearings are stationary relative to the hub / shaft so wouldn't make noise? Maybe it's as simple as the selector fork catching in the hub ring slightly being in a different position when selected.

 

[Geoff Bart]

Jon, that is an interesting thought. Yes, that's right!! (I think?), the actual gear needle bearings for each particular gear are only spinning when it is not the actual one selected and driving the output. Will try a little pressure one way to the other on the shift stick while idling in 5th gear (transfer in neutral) to see if it could be something to do with the selector forks/hub.

If nothing of note there will start exploring to see if the issue is further along the drive line (gearbox output to transfer or something in the transfer box itself). Doing the transfer drain and refill this evening as a first step to follow up on Dave's earlier suggestion that the issue might actually be in there (transfer box).

 

[Geoff Bart]

Since last post have now drained the Transfer Box...............and have come up empty again. Just clean oil and no deposits at all on the drain plug magnet indicating any looming catastrophe. Which is good I guess ...... but still no closer to any conclusions on this.

So that's the end of it for now. I'll just keep driving the old girl and monitor the symptoms. Apart from the odd rumble from the gearbox at idle (in 4th & 5th) and very minor noise in same gears at highway speed the gearbox and transfer continue to perform flawlessly. (Just hope now it all doesn't end in tears somewhere far from home). Thanks again to all for the thoughts and suggestions.