Had one guy help me out allot here with a link to d-90.com....however I am looking for a little more. I know a little about D-90's but could use some help with people that actually use them and have years of ownership experience. I figure the old GM block V-8 should have most of the bugs worked out of it, and I know that early 94 models have transmisson issues. Also I know that the axles are weak due to 24 splines, bi-level gears and poor material used. How weak are the tranny/axles? Can you abuse the truck in stock form without breaking stuff....to a point? If so what is the max tyre size so as not to be a show rig? Could you run 33's? I think the T-case is all gear drive....any issues with that? Generally I am looking for people who really use these trucks and the issues that they have had with them.

the lt77 and r380 are both prone to losing syncros over time and be come difficult to impossible to shift. The zf auto doesn't have problems with our low hp rating. Just make sure it has fluid and you'll be fine same for transfercase (lt230) just keep fluid in it. Axles are weak but can be upgraded to nearly indestructable with 35s or less. There are several people that have aftermarket shafts that haven't failed with that size tire. Cvs on the other hand are going to break. That's your weak link right there. With the original diffs right behind that. There are lots of options for upgrading. If you have an auto and stay with 33s and use a selectable locker in the front you'll have a hard time breaking stuff if you drive smart. These are not vehicles that you can get it with in stock form you will break cvs and shafts (in stock form) Search for more information on upgrading stuff. That should give you a good start on where to look.

-ben

Ben is right,

but just to prove there is always one nutter.......

I stripped the teeth off the large gears in my lt230 over the weekend in the tomcat. Yes,it did have oil. I'm blaming the fact I put in a new input drive gear, and it did not like the mating gears due to wear and eat them.

But then, I had NEVER heard of a transfer case letting go before.

Merv.

Thanks for the info....ok so as I read your responses as long as you stay with the stock rubber you should be ok for getting in it once in a while off road. I drive pretty smart (most of the time), the D-90 I am looking at is going to stay stock and open on both ends. I know the axles suck.....along with the tranny but I have always been a fan of Rover's. I have a hard core rig and just want to beat around the bush once in a while with this without the fear of not being able to stand on it once in a while in order to get my self out of a bad spot. How often have you seen bone stock units break stuff?

I should add to the above......how often have you seen early manual versions that are bone stock break stuff?

What will go first if you stick with stock axles? Cv's, diff or stock axles. If you upgrade to heavy duty axles are you more prone to break cv's and diffs? If that is the case is it not cheaper and an easier trail fix just to carry a spare axle or two? Just wondering. That has always been my fear of upgrading to heavydut axles. Is my fear unfounded?

A stock truck unlocked will have a tough time breaking stuff with stock tires. And it will be still surprisingly capable. Take off the sway bars and retain the springs and you'll have quite a good little off road truck. The trannies just take time to go bad has nothing to do with going off road or not. I've seen several go at about 75k and have seen one that had 145k with the original clutch. Don't know what the magic behind it is.
Sticking with stock axles and stock tires I would think that the diff would blow first. That was my first causality but then again I was hammering on it with stock gears and 35s. Yes you are more prone to break something else once a weak link is upgraded. That's why I would replace an axle at a time. Do the rear first (upgrade diff axle lower gears) then do the front (cvs axles diff) yes it is an easier trail fix to change an axle but you're probably going to blow a diff first which isn't a quick and easy trail fix unless you carry a spare third member then it's just 10 bolts or so on the diff four on the driveshaft and you're ready to go

-ben

I'd advise stronger half-shafts (axles) and 4-pin diff's, then start looking for uprated CV joints.
You might want to change out the transfer box for a 1.44/1 to get the gearing sorted out for the 33" tyres.

Planning on keeping it bone stock at this point. Just wanted to know how much hell I can give it without breaking parts that's all. Are the axles the same used in the early model Range Rovers (1975)? I have seen one of those that got abused for years without breaking any mechanical stuff (other than the rear self-leveling unit....but that was after being jumped and about 6ft in the air). The tyres were much smaller (205's on 15" wheels If I recall correctly) so I don't know how well the axles would have held up with the 31's on the D-90. I know the engine was the same Buick block only 3.5L not 3.9L and only 130hp. The tranny was a 4 speed and the transfer case was full time with a center lock only it was activiated with a switch not by moving the lever to the left. Weight wise it was probably a little lighter than the D-90 although very close. That vehicle had zero drivetrain issues stock but like I said it was on much smaller rubber and a perhaps a little lighter with less hp.

no the rangie was worse, having 10 spline axles vs. your D-90's 24.

With the manual transmissions, use manual transmission fluid MTF94 - your syncros will love you.

LR recommended automatic transmission fluid, but now recommend MTF94, which has additives that are better for manuals.

Dont use heavy gear oils - the oil pump will not cope with the higher viscosity and will wreck your transmission.

Ben is right,

but just to prove there is always one nutter.......

I stripped the teeth off the large gears in my lt230 over the weekend in the tomcat. Yes,it did have oil. I'm blaming the fact I put in a new input drive gear, and it did not like the mating gears due to wear and eat them.

But then, I had NEVER heard of a transfer case letting go before.

Merv.


Merv M8 i blew the living daylights out of the t box on my 300tdi disco a month back.The teeth on the input gear and secondry gears were striped.Also the bearings on the secondry sharft have gone walkies.

So thats two of us on this side of the pond that are nutters :grinpimp:

A question for Merve and Wavey Dave.

What serial number was the LT230 that the gear teeth failed in?

From what Mal Story told me, Rover have made changes to the pressure angle and helix angle of the gear teeth in different models of the LT230.

Smaller pressure angle results in quieter gears at the expense of strength.

Bush65

Sorry for the dealy in answer.Been busey for quiet a while it seams.

Dont know the number of the LT230 box as it went to the scrapy a long time ago.It was how ever the stock box for a 1994 300tdi manual gearbox discovery.

Dont use heavy gear oils - the oil pump will not cope with the higher viscosity and will wreck your transmission.

I've never seen a 90 with the oil pump in the tranny. Discos and 110s yes, but not 90s.

I'd be more worried about the synchros with a heavy gear oil. When the lube is too thick, the synchros take forever to engage and people force the shifts.

IME, the synchros will last as long as any other gearbox if treated properly and a quality manual transmission lubed used (instead of ATF). Don't force the shifts and let the synchros do their job.

I personally had an LT230 lose a gear tooth... But in my judgement of the gear failure it was a casting defect.

As to axles, it depends on the year. On the newer stuff, the CVs are the weak point, then either the halfshafts or diff centers will go.

Speaking of synchros...
I've been suggested (years ago) from mechanics and lorry drivers to "double de-clutch" when shifting down as this should make the synchros live longer...

Is it true or just bull*cks?
:confused:

If you keep your fawking hand off the gear shift when not shifting, life of the second gear synchros will be much longer.

I find it very curious that Rover trannies behind anemic V-8s and not particularly powerful diesels don't seem to last nearly as long as those found in my old Chevy hot rods in the past. I wonder if it is a material issue, not design, nor driving habits.

If you keep your fawking hand off the gear shift when not shifting, life of the second gear synchros will be much longer.


I lost my fawking right hand thanks to a lightsaber when I was a young Jedi knight :vader2:
Call me "Hook".

Even the owner's manual suggests not to keep the hand on the lever,
You didn't reply my double declutch Q.
:flipoff2:

My driving habit is pure finesse!:D

As I stated, IME, the synchro should never wear. I know people with very high mileage and they shift as new.

Light pressure on the synchro and give it time to synchronize the gears. Too much force and the oil film is lost causing wear. Gentle hands make for long synchro life... :grinpimp:

You didn't reply my double declutch Q.


(Pendy voice on) It was so obvious that it didn't deserve a response(Pendy voice off).

Anybody who's owned a Series truck is already doing this out of habit!

(PT boyscout voice on)I really didn't mean for any of my comments in this thread to sound so nasty(PT boyscout voice off)

I've never seen a 90 with the oil pump in the tranny. Discos and 110s yes, but not 90s.

Errrrrrrrrrrrm, LT95/77/85's all have an oil pump in them.

swag

Anybody who's owned a Series truck is already doing this out of habit!

Call me out then,never had a Series...
:(

Errrrrrrrrrrrm, LT95/77/85's all have an oil pump in them.

swag

OK, I stand corrected. I've never seen coolers on any but the Discos and 110s and didn't realize they had pumps.

Thanx!