Transmission & T-case: Transfer Case


Topics covered:

Overhaul & Input Gear Upgrade

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From: Craig Reece[SMTP:craigreece@earthlink.net]
Sent: Wednesday, December 20, 2000 12:23 PM
Subject: Re: [D90] transfercase leak??

> Directly aft of the Transfer Case is a large cylinder looking thing
> that then connects to the U-Joint and rear drive shaft. What is the
> name of that part? and is there a gasket where that part meets the U-
> Joint? I am slowly, but surely spinning gear oil out of there.

The handbrake drum assembly is held onto a shaft from the transfercase by a big nut - it's at the rear of the drum, and you can't see it because i'ts concealed by the u-joint or CV joint, depending on which you have. On mine, this nut loosened, allowing gear oil to leak all over the brake shoes. I replaced the brake shoes and reinstalled the nut using Locktite, and so far so good.

Craig Reece

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From: Gomes, David
Sent: Monday, November 06, 2000 9:48 AM
Subject: [D90] LT230 manual

THIS ugly american doesn't recognize the language of the site (Dutch?), but the reference materials are in english. Of main interest here being the PDFs of LT230R transfer case manual. The link was originally posted to LRO by Kristjan Vaarmann.
http://www.landrover.ee/est/faq/downloads/downloads.htm

-Dave G.

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From: Clarke Williams[SMTP:clarkewilliams@halcyon.com]
Sent: Wednesday, July 19, 2000 1:32 PM
Subject: Re: [D90] 94 vs 95 transmission

>I think it's also worth mentioning that some later production 5 speeds came
>with a different input gear in the transfer case with four holes in it to help
>reduce spline wear. I don't know if the change occurred at the same time as
>the change from LT-77 to R380. The newer style gear can be retrofitted to
>older style vehicles.

George,
That change was at Suffix "C" for the LT-230T. The length of the spline was also later lengthened to attempt to resolve some spline wear issues.

Later cases (often called "Q" cases although "Q" does not appear in the serial number) changed the tooth angle and tooth count of the input gear and intermediate gears to make the transfer box somewhat quieter. As this change appeared after LRNA stopped bringing in Defenders, you only see "Q" boxes in Discos and RRs in the US.

Early Torqueflight 3-speed autos (Rangie gearbox until 1986) cannot be used with the later LT-230Ts due to the longer spline engagement. You would have to re-spline the coupler shaft or replace the input gear.

Clarke

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Engaging Center Diff Lock

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From: Robert Dassler[SMTP:roadsiderob@hotmail.com]
Sent: Monday, March 20, 2000 9:13 PM
Subject: Re: [D90] 4 Wheel engagement problems

If your friends car is a 94 or 95, it only has mechanical linkage. If the car is a 97, it could have electrical problems. The 97's have an interlock system that uses a solenoid to keep the transfer box locked in gear. the transfer box can only be shifted when the trans is in neutral. I don't have a schematic in front of me but basically, there are a couple of microswitches in the trans shifter housing that control the solenoid. The system is also tied into the key interlock system that prevents the keys being removed unless in park. The diff lock light not coming on is probably a different problem. Has the drivetrain been apart recently? perhaps the connector at the t-box is disconnected. I have seen very few solenoids fail. problems are usually in the shifter switches or wiring. As for the diff lock, engage it and jack one wheel up. If the wheel spins free--the diff lock is not engaging and you have a mechanical problem. If the wheel is locked, you have an electrical fault. I replace a lot of diff lock switches. The contacts can come loose when the wiring is disconnected or they develop high internal resistance. If the mechanical test passes, jump the diff lock leads together--if the light comes on the it is a good bet that the switch is faulty. lastly, if the trans or t-box has been out--inspect the linkage carefully. It is possible to reassemble the linkage sort of upside down in such a fashion that it will not shift high to low.

Good luck
Rob Dassler

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From: Alan Dobbs[SMTP:gulfcmt@flash.net]
Sent: Wednesday, November 29, 2000 8:51 PM
Subject: RE: [D90] RE: 4-High

> I currently have a 1995 D90 SW in which I cannot engage
> the 4-high or diff-lock,

It has happened to our D-90 [Alan's is a 1997, earlier linkages are stronger - Ed.] many occasions.
There is a poor designed stamped metal linkage that connects the rod linkage to the transfer case.
When under a hard push or pull on the diff lever (to go into hi or low) the linkage bends causing it not to engage. I just beat it back and reassemble. It can be removed from the bottom or access thru the top by removing the access panel between the seats.
Before you tear apart the D-90 I would have a person move the linkage back and for the while you feel the linkage from the bottom. Be careful not to smash your fingers.
Also you could remove the linkage and see if you can manually engage from hi to low. It may help if the D-90 is on jack stands so you can rotate the tires to let is slip into gear in the T-case.

Alan

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Date: Thu, 27 May 1999 09:22:15 +0100
From: jimallen@onlinecol.com (Jim Allen)
Subject: Re: [D90] Center Diff lock: A cautionary tale!

Doug A. wrote:
>A good friend has just rolled his Disco while driving a fairly smooth
>gravel road at @ 35 mph. Analysing the event (I was not there) I think one
>of the principal causes was that he was in center diff lock.
>Why? As y'all know, when in diff lock you force the front and rear drive
>shafts to rotate at the same speed. So as you drive round a curve and the
>rear wheels track a lesser path, the wheels themselves must rid themselves
>of the extra distance by spinning. Not much, perhaps, but just enough to
>lose traction. If they do not lose traction, they will try to drive the
>same distance by taking a wider line: i.e. your tail will swing wide......
>Either of these effects will make your rear end loose. This is precisely
>what happened in a relatively innocious curve at a reasonable speed. His
>tail went light and started swinging wide. Attempts to correct just
>increased the amplitude of the fishtail (overcorrecting) until he clipped
>the bank and did his roll(s). ended up on his roof after (he thinks) 2 1/2
>rotations.
>He was (thankfully) unhurt and left suspended from his seat belt (the
>wearing of which quite possibly saved his life!) and friends following (in
>a stretched out convoy due to road dust) were able to extrace him and roll
>the vehicle upright with straps.
>
>Lesson to be learned: don't drive in diff-lock unless the terrain really
>warrents it: you will strain your drive train and decrease your vehicle
>stability.

RE DIFF LOCK: -

Good advice, Doug! I've seen the same scenario several times, though in every one I saw, excessive speed for the conditions was always a contributing factor. I was instructing in a D90 with a student driver in '96 and this exact scenario happened (less the rollover). We didn't SEEM to be going too fast, but that off camber gravel turn (not a tight one even) said otherwise. YEE-HAA! No wreck but it was close. D90s are hard to get back when they start to switch ends. Somehow my driver did it. He was Japanese and I learned a couple of curse words in that language as it occured. It was an error in judgement on my part for letting him go faster than conditions safely allowed. I read that section of road all wrong!

As a counterpoint, I know of at least one expert driver (well two, if I include Lea Magee) who prefers having the center diff locked under these conditions, a fellow named Malcolm Smith. Lea and Malcolm like the front axle to he hooked up so they can power up to straighten the rig out. I've seen it work (look at some of the all wheel drive Pro Ralley cars). Smith and Magee argue that without diff lock, if you power out of a turn with low traction, the power transfers to the tire with the least traction - - usually the inside rear wheel. True, but it's a squirrellier situation with it locked for most of us. I would argue just what Doug did, but I'm not going to second guess Smith or Magee if it works for them.

Still the newer Range Rovers will lock automatically and and the driver has no control (very little anyway - sometimes you can cause it to lock and unlock with the throttle if you are "finesseful"). Then What? The new Discos don't even have the diff lock hooked up (it's there in the 'case, however,at least in the early models, and you could hook it up to a seperate control).

One other addendum to Doug's advice is not waiting too long to engage diff lock on the trail. We're not talking about speed here - like a fast gravel road - just slow, off-highway terrain in general. When I was wrenching on the '87 and 88 RRs (nearly the same LT-230 as in the D90), we had a lot of center diff failures on rigs that actually saw trail use (used often in the desert in sand, etc). Why? Because the drivers waited till they were actually (or nearly) stuck before engaging diff lock. Up to that point, that little center diff (it is little!) was working very hard. They can actually be overheated and spit the shims out and/or grenade. Saw a lot of them turned blue- and with the t-case full of (burned) oil! One of our big pushes in the driver training programmes was to teach proper use of the manual center diff lock for the above reasons.Our basic advice was, "Engage diff lock at the point past which you wouldn't drive the family Buick." Over simplistic for more experienced drivers, perhaps, but a good starting point for novices. FWIW

Jim Allen

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Stock Ratios

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Date: Thu, 29 Jul 1999 08:26:55 +0100
From: "Dave Ashcroft" info@autoconv.com
Subject: Re: [D90] Re:Transfer case ratios

Hi,
There are basically 4 different high range ratios used on the LT 230 transfer case, all the low ranges are very similar if not identical.

1.003
Highest is the 1.003 used on the 3 speed RR auto

1.2
Next down is the 1.2, I call it the 1.2 because over the years there have been many variations on this ie it has ranged from 1.192 to 1.222 to 1.211 and now 1.206 but these can all be treated as the 1.2 which is used on :
RR Classic 5 speed manual
RR Classic 4 speed auto
All Discos
and the V8 D 90's

1.410
Next down is the 1.410, this is used on all LR 90's bar the V8 and all LR 110's bar the very early LR 110's with the 2.5 N/A diesel and the 2.25 petrol .

1.667
lowest is the 1.667 used on the very early LR 110's with the 2.5 N/A diesel and the 2.25 petrol .

Hope this is useful,
Dave

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GBR Low Range Gearset (crawler gears)

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From: Bill Ritchie[SMTP:billnsandi@kingwoodcable.com]
Sent: Monday, January 10, 2000 5:08 PM
Subject: [D90] Crawler Options - was RE: Automatic gearboxes

I have to jump in and help with some cost numbers here for those interested.

GBR LT230 Gear set - $1995 (plus $500 refund. core charge) plus shipping.
Yields a crawl ratio of about 70:1 depending on R+P

Ashcroft Crawler Box - 1500 British Pounds ($2455 plus duty and shipping)
Yields a crawl ratio of about 120:1 depending on R+P

I don't know what the duty and shipping for the crawler would be, but for my ring and pinions and axles it wasn't too bad.

Bill Ritchie

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From: Richard Hills[SMTP:rhills@nmsu.edu]
Sent: Thursday, July 20, 2000 5:26 PM
Subject: [D90] GBR gear set

Doug, others,
I am about ready to install my transfer case back into my d90. Plan to test the GBR gear set this weekend on one of our moderate trails.

Observations so far:

1) The engineering of the gear set appears to be quite good. The quality of workmanship is at least as good as stock and the design appears to be very conservative (more so that stock).

2) One must remove the transfer case and remove all of the gear/shaft clusters. Some of the bosses in the case must be ground down to make room for the larger bull gear. Very little material had to be removed from non structural areas. Removing this material will not weaken the case. A standard 5" grinder can be used and this operation doesn't take long. One must also relocate the magnetic drain plug. The magnet is long enough that it would hit the larger bull gear. A non magnetic plug is provide to fill the existing hole. One must drill and tap (a tap is provided) a new hole about 70 mm from the existing one. Be careful that you drill and tap this straight - or the plug will leak. I had enough damage on my transfer case from rocks that I took it down to school and used a mill to drill, initiate that tap, and to mill a flat for the relocated magnetic plug.

3) The rod on the high/low shift fork must also be ground some to provide clearance for the bull gear. The strength of the fork is not compromised as the material removed is less that that already removed for the shift detents.

4) A new bull gear is provided for low range. Replacing this gear is the only operation that requires special tools (a gear puller and a special socket to remove the bearing retainer stake nut - I fabricated a simple one out of some steel I had laying around). Preload adjustment is not required on this shaft, but I suggest you order a new stake nut. You do need to use a torque wrench on this nut - so you do need some sort of special socket rather than an adjustable wrench.

5) The stock input shaft and gear is simply slide out of the case. Preload does not need to be readjusted.

6) The entire intermediate shaft/gear cluster is replaced with a new one. Normally, you would have to use a crush washer on this shaft and adjust the preload correctly. However, the MaxiDrive shaft/gear cluster uses two sets of roller bearing that are opposed to absorb the shaft thrust and radial load. These bearings are already installed "inside" the gear cluster and have the correct sized, non crushable preload sleeve already installed between them. There is also a third bearing (needle bearings) under the low range gear to absorb its radial loads. The gear cluster is very easy to install. One simply holds it in place in the case and slides a shaft through through the transfer case wall, through the gear cluster and bearings, and out though the opposite wall. A nyloc is provided (replaces the stake nut on the stock shaft) and is torqued to 80-90ft-lbs.

All I have left to do is put the bottom plate on the case, reinstall it in my vehicle, add oil, and give it a try. Will let you know how it turns out.

Rich

Rich [SMTP:rhills@nmsu.edu] later added:

I have the newer transmission, so my low is not as low as yours (Doug M.). I also have 4.11s rather than 4.7s, so I'm around 63:1. Yes, this new ratio has pushed the automatic transmission down to near bottom of my to-do mod list. I'll run these gears for a while before I decide whether to simply put in 4.7's or go with the automatic.

I installed it myself with some help lifting it in and out from my friends. Lance Harkey (you meet him at Independence) came over Saturday morning about 10:30AM to start working on the conversion. We had the transfer case out and disassembled by 1:30PM. Sunday, I modified the case (the grinding took very little time, but I was very careful in relocating the drain hole), cleaned the case, and removed the bull gear from the output shaft. The rest of the week, I made some tools (a sleeve to press the bearing and bull gear back on, the socket to properly torque the bearing retainer nut, an adapter plate to bolt the transfer case to my floor jack) and reassembled the transfer case. Sheila and I normally eat with some of my 4x4ing buddies on Friday night. After dinner, they wanted to come over (about 8:30 PM) to help put the case back in. We finished by 12:00 Friday night.

Maxidrive provides 2 pages of clear instructions (with color pictures) for the modification to the case, but does not provide instructions concerning removal of the transfer case from the vehicle or disassembly/re assembly of the case. So one definitely needs a LR shop manual that discusses this in detail (my 93-95 manual does, my 97 manual does not). The transfer case is also quite heavy (because of the differential/housing and the brake/output shaft housing), so I highly recommend a transmission jack and a mount to hold the transfer case at the required angle (30.5 degrees) for installation. It is too easy to mess up the input shaft seal if you try to man handle it. I have a transmission jack adapter that mounts on my floor jack. I made an adapter plate to bolt the transfer case to the jack.

Would I do it again - in a flash. Everything worked first time. Our Jeep friends have had much more trouble with their 4:1s. These are not very dependable set-ups. The gears fail and the new casings come in warped. One of my friends had his TJ in and out of the shop for over a month before he got it to shift in and out of 4wd. Lance Harkey is on his 3rd set of gears in his transfer case.

I will be up on Blanco this Sunday, around B.Vista Monday and Tues (Iron Chest, Wheeler Lake), and don't know where on Wed. Would like to do Independence again on Wed., but don't have a winch with us.

Rich

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From: Richard Hills[SMTP:rhills@nmsu.edu]
Sent: Saturday, August 05, 2000 4:22 PM
Subject: [D90] Q, lower gears, brief trip report, and winches

Q, I am very happy that you really like your suspension and SSR's. This combination really makes the d90 a very capable vehicle.

We just got back from our Colorado vacation and had a great time. We did 5 trails including Blanca, Iron Chest, and Holy Cross, Mt. Ontero, and one in New Mexico. I was very pleased with the performance of the GBR gear set. For you guys that have done Iron Chest, I was able to lead through the rocky section (I have never done Iron Chest before) without any spotting and without using the clutch. I did hang up the rear diff once and had to back up once to take a slightly different line. I did hit very low rpms for a few instances, but the engine didn't stall. Blanca was also done without having to feather the clutch and never hitting low rpms. Simply drive through your line. The only time I had to feather the clutch while climbing was on the water fall above the cabin on Holy Cross. I also enjoyed the lower gear going down steep step-offs. On most of them you could simply drive off. On the tippy ones that I had to inch off (coming down Jaws II for example), I found that the lower gear ratio had enough torque that I could use the brakes and just a tad of clutch to keep moving without every needing throttle. My wife noticed a big difference in how much effort was required to drive the vehicle compared to last year on the same trails and liked the change (this was good as she was well aware of the $s involved :-)). The overlap between high range and low range is still plenty. I could run 3rd or 4th in low range or 1st in high range (I have 4:11s). The only down side was the noise of the straight cut gears. I found the noise annoying while going up the early miles of up-grade on Mt. Ontero while in 3rd, 4th, and 5th. When this was the case, I would put the transmission in high range 1st. However, going down grade or on level (i.e., when the transmission is not loaded), the whine was still there, but not bothersome. I tend to be more easily annoyed by such noises than others. It didn't bother my wife a bit, but she can sleep through my snoring!

Thanks for all the great input on winches! One question - does the roller fairlead mount directly to the Husky winch or does it require a separate bracket?

Rich Hills

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