R380 Gearbox

Posted on  by admin

R380 Gearbox The R380 box was introduced as brand new LR gearbox across the entire Land Rover and Range Rover product lines. The R380 is a radically reworked LT77 (The 1940’s Jag gearbox remember) with improved main shaft bearing arrangements that provided an overall strengthening of the box. The R380 name stands for “Rated to 380 Nm input”. R380 Battery Replacement Kit Compatible with Samsung Galaxy Gear 2 R380, SM-R380 and Gear 2 Neo R381, SM-R381 Smartwatch Repair Kit 4.0 out of 5 stars 33 $16.99 $ 16.

Every Land Rover nerd loves data. Especially if they are trying to do something a little different with the drive train. I've placed everything I could find about gearbox and Transfer case gear ratios here in a hopefully readable way. If you are feeling particularly nerdy you can also read my 'history of Rover gearboxes' web page.

Just for the fun of it I added the NP-435 close ratio gearbox and Ashcroft high ratio transfer case that is in The Green Rover for comparison. Then I got several requests to add other alternative gearboxes available used in the North American market. Specs for common alternative gearboxes have been placed on another web page.

NOTE: Ratios are rounded off to the nearest hundredth.

Some ratios:

  • Stock Series differential ratio - 4.7:1
  • Stock coiler differential ratio - 3.54:1
  • Common aftermarket differential ratios for the Rover differential carrier - 4.1:1 and 4.75:1
  • Standard Series transfer case high range ratio - 1.15:1 (making it an under drive) . Low range varies
  • Standard Coiler transfer case low range ratio - 3.32:1. The high range varies with the engine used.
  • Fairy/Superwinch overdrive ratio - 0.78:1
    (which coupled with the 1.15:1 Xfer case under drive gives you a 0.90:1 overall ratio through the xfer case)
  • Roverdrive overdrive ratio - 0.8:1
    (which coupled with the 1.15:1 Xfer case under drive gives you a 0.92:1 overall ratio through the xfer case)
  • Ashcroft high ratio kit high range ratio - 0.87:1
R380 gearbox problems

Some thoughts about low range first gear ratio: I found the stock Series Land Rover low range first gear ratio (40.7:1) to be too tall for most rock crawling and many climbing situations. Having 10 years experience with a 70:1 ratio I have found it to be too low for anything but the most technical rock crawling situations (with 33.3 inch dia tyre). At this time I'm leaning towards somewhere around 55:1 as being the best overall low range ratio for use in many different situations with 32 - 34 inch dia tyres.

Figuring out a differential ratio: If you have an unknown differential sitting in front of you, you can calculate the ring and pinion gear ratio by counting the number of teeth on both the ring gear and the pinion gear. Divide the number of teeth on the ring gear by the number of teeth on the pinion gear and you get the differential ratio.

Page Contents:

  • Series gearbox ratios
  • Series transfer case ratios and Ashcroft high ratio transfer case ratios
  • Comparison of stock series, Roverdrive, Ashcroft, 4:1 R&P, 3.54:1 R&P
  • Series overall final drive ratios for each gear, Suffix C & newer, 1-Ton & The Green Rover
  • Early coiler, 101 forward control, 109 stage 1 V8 gearboxes LT95 & LT77)
  • Late 5 speed gearbox (R380)
  • 6 speed gearbox (GFT MT-82)
  • Coiler transfer case ratios (LT230)

Series Gearbox Ratios: (Does not include 109 Stage I V8 which uses LT95)

R380Main gearbox
Suffix A & B
88 & 109

Suffix C on
88 & 109

Ser. III
88 and 109

Ser. IIA & III
109 1-Ton

Top

Direct

Direct

Direct

Direct

Third

1.37:1

1.50:1

1.50:1

1.50:1

Second

2.04:1

2.22:1

2.22:1

2.22:1

First

3.00:1

3.60:1

3.68:1

3.60:1

Reverse

2.54:1

3.02:1

4.02:1

3.02:1

Early Coiler, 101 Forward Control and 109 Stage 1 V8 Gearboxes

Main gearbox

LT95*
109 Stage 1, 101, Range Rover thru '83
V8 90/110 '83 & '84

LT85
All V8 90/110
'84-'91

LT77/LT77S
2.5L & 200 Tdi
'84 thru '93

LT77/LT77S
V8 Discovery thru '93
V8 90/110 '92 & '93

Fifth

none

0.80:1

0.83:1

0.77:1

Fourth

Direct

Direct

Direct

Direct

Third

1.51:1

1.436:1

1.507:1

1.40:1

Second

2.45:1

2.18:1

2.30:1

2.13:1

First

4.07:1

3.65

3.59:1

3.32:1

*Note: The LT 95 has an integral transfer case. A number of transfer case gears were available.

R380 Gearbox

Main gearbox
R380
All 300 Tdi Discovery & Defender
'94 to present
R380
All V8 Discovery & Defender
'94 to present

ZFHP22
Range Rover Classic
'92 - '03 Discovery, Defender V8

Fifth

0.73:1

N/A

Fourth

Direct

Direct

0.728:1

Third

1.30:1

1.39:1

Direct

Second

2.13:1

2.13:1

1.480:1

First

3.39:1

3.32:1

2.480:1

GFT MT-82 Gearbox

Main gearbox
GFT MT-82
'07 Defender
Transfer case

Sixth

Hi range: 1.211:1

Fifth

Lo range: 3.269:1

Fourth

1.223:1

Third

1.721:1

Second

2.839:1

First

5.443:1

Note: Overall low range first gear is 57.1:1 and overall high range sixth gear is 3.18:1

Series Transfer case Ratios:

TunnelTransfer case
II, Suffix A & B
88 and 109
IIA suffix C on & III
88 and 109
109 1-Ton
IIA & III
Ashcroft high ratio

High transfer

1.15:1

1.15:1

1.53:1

0.87:1

High transfer with 4.7 R&P

5.4:1 ( 3686 RPM @ 65mph*)

<- Same

7.19:1 ( 4900 RPM @ 65mph*)

4.01:1 ( 2737 RPM @ 65mph*)

High transfer with 4.1 R&P

4.7:1 ( 3208 RPM @ 65mph*)

6.27:1 ( 4279 RPM @ 65mph*)

3.57:1 ( 2437 RPM @ 65mph*)

High transfer with 3.54 R&P

4.07:1 ( 2788 RPM @ 65mph*)

5.42:1 ( 3699 RPM @ 65mph*)

3.08:1 ( 2102 RPM @ 65mph*)

Low Transfer

2.89:1

2.35:1

3.27:1

2.35:1

Low transfer with 4.7 R&P

13.58:1

11.05:1

15.37:1

11.05:1

Low transfer with 4.1 R&P

11.85:1

9.64:1

13.41:1

9.64:1

Low transfer with 3.54 R&P

10.23:1

8.32:1

11.58:1

8.32:1


Gearbox*Engine RPM calculated with 4th gear (1:1) and 32 inch diameter tyres (stock 109 size) Calculator at csgnetwork

LT230 Transfer case Ratios

Transfer case
LT230
Early Range RoverV8 D 110
300 Tdi
V8 D90
Discovery
2.5L Ninety, One Ten

High transfer

1.00:1

1.41:1

1.22:1

1.67:1

high transfer with 3.54 R&P

3.54:1 ( 2416 RPM @ 65mph*)

4.99:1 ( 3406 RPM @ 65mph*)

4.32:1 ( 2948 RPM @ 65mph*)

5.84:1 ( 3986 RPM @ 65mph*)

high transfer with 4.1 R&P

4.1:1 ( 2798 RPM @ 65mph*)

5.78:1 ( 3945 RPM @ 65mph*)

5.00:1 ( 3414 RPM @ 65mph*)

6.85:1 ( 4675 RPM @ 65mph*)

high transfer with 4.7 R&P

4.7:1 ( 3208 RPM @ 65mph*)

6.63:1 ( 4525 RPM @ 65mph*)

5.73:1 ( 3911 RPM @ 65mph*)

7.85:1 ( 5358 RPM @ 65mph*)

Low Transfer

3.32:1

3.32:1

3.32:1

3.32:1

low transfer with 3.54 R&P

11.75

low transfer with 4.1 R&P

13.62

low transfer with 4.7 R&P

15.60:1


Gearbox*Engine RPM calculated with 4th gear (1:1) and 32 inch diameter tyres (stock 109 size)

LT95 Transfer ratio ( Integral part of LT95 gearbox)

LT95 gearbox
transfer part
101 Forward Control11090, Range Rover

High transfer

1.17:1

1.34:1

1.11:1

Low Transfer

3.22:1

3.22:1

3.22:1

Overall gear ratio (final drive)

High transfer

gearbox positionSeries Suffix C & newer109 1-TonThe Green Rover
(NP-435 close ratio)

Low Transfer

High Transfer

Low Transfer

High Transfer

Low Transfer

Top

5.4:1

11.10:1

7.19:1

15.40:1

4.09:1

11.10:1

Third

8.05:1

16.50:1

10.80:1

23.10:1

6.91:1

14.47:1

Second

12.00:1

24.60:1

15.96:1

34.1:1

9.32:1

25.18:1

First

19.88:1

40.70:1

26.46:1

56.56:1

18.65:1

50.37

Reverse

21.66:1

44.30:1

28.91:1

61.78:1

R380 Gearbox Manual

Engine RPM comparisons for Series gearbox with Roverdrive or high ratio kit and for LT77S (same bellhousing bolt pattern)

Here is a comparison chart showing the differences for high range fourth gear (1:1 ratio) RPMs at 65 MPH with 32 inch diameter tyres mounted. Arranged in decending 4th gear RPM order.

vehicle & gearing

Fourth gear RPM (32' tyres)

Fifth gear or Roverdrive

2.5L Ninety and One Ten

3986 RPM @ 65 MPH

3349 RPM @ 65 MPH

Stock Series Land Rover

3686

2951

V8 Defender with 4.1 ring and pinion

3414

2628

tdi Ninety and One Ten

3406

2827

Series Land Rover with 4.1:1 ring and pinion

3208

2554

V8 Defender

2948

2270

Series Land Rover with 3.54 ring and pinion

2788

2223

Series Land Rover with Ashcroft high ratio kit

2737

R380 Gearbox Tunnel

This data came from several sources. It started with a 1971 Land Rover technical document and mid eighties Rover Ninety and One Ten dealer hand out brochure and grew through the help of many people who volunteered additional data through e-mail. Particular thanks to John Barge for his help in sorting out the coiler gear ratios.

R380 Gearbox Problems

Home‎ > ‎

R380 Gearbox


This section is dedicated to the R380 gearbox found on a manual P38 Range Rover.
In my case, I am doing this overhaul because when the gearbox was at full working temperature, the 4th gear tent to grind allot. Don't know why but when cold, the gearbox didn't show any problem.
Since had to take my engine out! Out came the gearbox also.
The manual gearbox fitted in these DSE's is a Type D gearbox. My particular one is a suffix J.
It is important to know this because if you are going to service the gearbox, the service manual the parts ordering must match that particular gearbox.
The type can be figured out by the manual and the suffix is the last letter of the serial number.


I recommend that you read the overhaul manual first and then start braking the gearbox apart.
Second thing you need is a crazy enough friend to help you on this heavy task.
Phew... This is heavy...
I removed the engine and gearbox because the engine died and needed special care and attention.
I can't be much of a help in concern of taking the gearbox alone. This site has an example of that.

Here it is! The box itself striped from ancillaries.

First half removed exposing the 5ft and reverse gears.

Now this nut... This nut is supposed to be torqued to 220Nm and LRT-37-023 special tool (I love tools that are special), has per manual, is to be used to hold the 5th lay-gear.
Since this tool costs £124.94 +shipping it's not worth to use only 2 times, so I built my own.
I remember reading on a forum that one can engage 5th and 3rd or 4th gear at the same time and use an air gun to undo the bolt. It seems that this is the preferred method around the shops. Someone suggested a rag or a old inner tube between the gears so that they stay put while you operate the air gun.
Because I also don't have a air gun and only a 6lt air compressor, I had to do it by my own brute force.

This is what I built with the tools, nuts, bolts, bits of metal and some grinding tools.





With this assembly I can set it on the floor and with a long breaker bar, undo the nut. My back still hurts...

A long 32mm deep socket is needed to do the job.

Here is one problem... More expense...

This is the 3rd and 4th gear synchromesh. Now I can see why the 4th gear was grinding.

It's amazing how the broken bits managed to get out of the synchromesh and just lay down on the bottom of the gear case.

R380