Stock Low Range Gearing

[GURU]

G'day all,

I was wondering does anyone know for sure that all LT230 low range ratio's are the same?? I have a 84 model 4dr that was an auto and someone converted it to a manual (LT77) but kept the standard transfercase. I then fitted a R380 and left the original TC in as well, But have since fitted a LT230 out of a 1996 disco that was fitted with a 300tdi. For some reason my low range gearing feels higher than it use to.

I swapped the TC as the auto one was a 1:1 high and the disco one was 1.2:1 for on road driving, but low range feels higher.

If no one knows I will pull the TC apart and count teeth. does anyone know the standard teeth count? thanks

[ISUZUROVER]

I am 99% sure that ALL LT230's are 3.32:1 low range - unless someone has ftted Mal's 30% lower low range kit.

You know that the 1st gear in the LT77 is lower than in the R380 don't you?
First low with an LT77 and 3.54 diffs is about 43:1
First low with an R380 and 3.54 diffs is about 39:1.

And the LT95 gives 48:1 with 3.54's,

[will_warne]

As far as I know thats right. One thing to add, though, is that MOD spec R380 gearboxes had a 20% lower first and second gear to help with towing.

[red90]

http://members.shaw.ca/red90/gears.html

[HSV Rangie]

all the same.

3.32-1.

Michael.

[TuffRR]

Yep, all the same. High range ratios are the only difference between LT230's.

[ISUZUROVER]

http://members.shaw.ca/red90/gears.html

I notice you don't mention Range Rovers there John. Do you know if the early LT77 rangies had the higher or lower ratio LT77 gears?

Also if you are updating the page - the 1.003:1 LT230 was also fitted to the ISUZU powered 110's (with LT85).

[uninformed]

I am 99% sure that ALL LT230's are 3.32:1 low range - unless someone has ftted Mal's 30% lower low range kit.

You know that the 1st gear in the LT77 is lower than in the R380 don't you?
First low with an LT77 and 3.54 diffs is about 43:1
First low with an R380 and 3.54 diffs is about 39:1.

And the LT95 gives 48:1 with 3.54's,

Ben, none of my books have specs for the R380 but have allmost every other. just wondering when/how you know this. a few people i have spoke to(that i thought would know) seemed to think that, in the defender in any case, it was the same as the LT77. 39-1 no wonder it sucks. anyway my 4.1s and MD low rang will help.

cheers, Serg

[ISUZUROVER]

Serg. - the info is out there... Have a look at John's (Red90's) website linked above.

R380 is 3.39:1 1st (Tdi) and 3.321:1 1st (V8) Low is 3.32:1 and diffs are 3.54:1

For R380 Box
Tdi - 3.39 x3.32x3.54=39.84:1 so roughly 40:1
V8 - 3.321 x3.32x3.54=39.03:1 so roughly 39:1

For LT77 Box
Tdi - 3.692 x3.32x3.54=43.39:1 so roughly 43:1
V8 - 3.321 x3.32x3.54=39.03:1 so roughly 39:1

[GURU]

Okay i did know there is a differance between the LT77 1st and the R380, but I have only noticed this increase in gearing since the TC change, was good before.

I am running 4.11 maxis and I think the gearing is too high, puts it at about 46.2:1

I'm also 99% sure that the previous owner didn't put maxi gears in

[red90]

http://members.shaw.ca/red90/gears.html

I notice you don't mention Range Rovers there John. Do you know if the early LT77 rangies had the higher or lower ratio LT77 gears?

Also if you are updating the page - the 1.003:1 LT230 was also fitted to the ISUZU powered 110's (with LT85).

Well..... LOL.. I don't have a RR workshop or parts manual. Never owned one. Actually, there is one on the net, so might look there.

Most data is from the genuine parts and workshop manuals. Some of the LT77 and R380 data has been adjusted from discussions with Mr. Ashcroft. One day I was going to try and get him to check a few more things and go over and count some more gear teeth for me.

If anyone has a box apart and wants to count ratios by teeth, send it along.

Yes, as you see, the diesels lost some gearing in the change to the newer box. Fortunately, I have a military LT77 on my 90 with a reasonable 4:1 1st gear.

I'm actually in Oz at the moment, so will need to try and remember next month as I can't ftp from here.

[ISUZUROVER]

Cheers John, - on a side note, do you know how much the gears cost to convert a normal LT77 to a military one? I assume you just need to replace the manshaft and layshaft first gears? - assuming the layshaft isn't one piece with the gears like on a SIII box.

What is happening in OZ? I thought the G.O.S. project went belly up???

[Bush65]

Cheers John, - on a side note, do you know how much the gears cost to convert a normal LT77 to a military one? I assume you just need to replace the manshaft and layshaft first gears? - assuming the layshaft isn't one piece with the gears like on a SIII box.

What is happening in OZ? I thought the G.O.S. project went belly up???

Layshaft is one piece except for 5th gear.

My Haynes manual for Disco was not very helpfull for gear ratios - only one list for low and high range, although discos used LT77 up to mid 94.

Anyway it lists overall ratio for 1st low as 43.367:1

[Aquarangie]

I will add that the early Chrysler 727 autos used 1.003:1 high range and that would make ytour gearing on-road too tall. Low range same as norm.

I think the later LT95's have a 1:1 high range in the Rangies, like the 83 I have aquired. May be wrong.

Regards,

Trav

[GURU]

I checked the low ratio of the old TC and it is 3.32:1

[ISUZUROVER]

I checked the low ratio of the old TC and it is 3.32:1

Maybe the bearings are a bit tighter and the T-case is sapping more torque now, or your engine has dropped in torque a bit - either could make the gearing seem taller.

[red90]

Cheers John, - on a side note, do you know how much the gears cost to convert a normal LT77 to a military one? I assume you just need to replace the manshaft and layshaft first gears? - assuming the layshaft isn't one piece with the gears like on a SIII box.

What is happening in OZ? I thought the G.O.S. project went belly up???

Too many parts as stated. Easiest thing is to get a 2nd hand used box. Relatively easy around here, surprisingly enough.

http://www.pirate4x4.com/forum/showthread.php?t=237396

I'm here for the final inspection. Project is not over, just supposed to be moving to the next stage....

[Maxtd5def]

Anyway it lists overall ratio for 1st low as 43.367:1

I've seen this figure before, but never been able to figure out how its calculated.


Anyone else been able to recontruct it? With quoted 1st gears?

Regards
Max P

[TuffRR]

Anyway it lists overall ratio for 1st low as 43.367:1

I've seen this figure before, but never been able to figure out how its calculated.

Anyone else been able to recontruct it? With quoted 1st gears?

Regards
Max P

43.367 = 3.54 (diffs) x 3.32 (xfer) x First gear ratio

This would mean that first would have to be 3.69:1. This is the ratio used in tdi LT77's whereas the V8 LT77's had a first gear ratio of 3.321:1

[uninformed]

Serg. - the info is out there... Have a look at John's (Red90's) website linked above.

R380 is 3.39:1 1st (Tdi) and 3.321:1 1st (V8) Low is 3.32:1 and diffs are 3.54:1

For R380 Box
Tdi - 3.39 x3.32x3.54=39.84:1 so roughly 40:1
V8 - 3.321 x3.32x3.54=39.03:1 so roughly 39:1

For LT77 Box
Tdi - 3.692 x3.32x3.54=43.39:1 so roughly 43:1
V8 - 3.321 x3.32x3.54=39.03:1 so roughly 39:1

Hey all, i was at maxi-drive the other day and mal had a r380 apart, so i asked about 1st gear not being as low as the lt77 and he seemed to think the tdi was and the v8 wasn't. so we did a tooth count.
Main gear box
Primary 33/22 = 1.5
Low 13/32 = 2.46

1.5 x 2.46 = 3.69

so: 1st 3.69 x
lt230 primary 1.58 x
lt230 low 2.10 x
final drive 3.54 = 43.34

ben any thoughts on this, have i missed something??? the r380 was from a tdi.
cheers, serg

[ISUZUROVER]

That is interesting info Serg, great work. Interestingly, a 4th gear ratio of 14/31 (x 1.5 input gears) gives the 3.32:1 V8 ratio, so it seems that the V8's must have 14/31 gears and the Tdi's have 13/32 gears.

All the info I have ever read though has quoted the 3.39 instead of 3.69 - maybe somewhere the information was incorrect and other people have just copied it. Or maybe Australia got different Tdi ratios but I find that doubtful.

[justinC]

Hi all, Just to throw a spanner in the works, I have a Isuzu 110 county LT85 and Lt 230, and it is 1.213:1..
This is still the genuine transfercase from the factory as I know the vehicle's complete history.
Could some of these 110's have had a mixture of ratios? Maybe in the trayback versus the wagon?

JC

[ISUZUROVER]

Maybe they ran out of the 1.003:1 on the day they built yours??? Surely the gear would have been replaced with a cross-drilled one when the mainshaft oiling problem was fixed though?

Mine definitely has the 1.003 ratio.

[1tonsoup]

Did the 101 LT95 box ratios differ from the Rangie at all? I have seen an answer to a question in a mag telling the reader to change in order to increase the gearing in the 101.

[uninformed]

not that i know of. at the time of development it has been said that rover could only afford to design one gear box. as they thought the military contract was a better bet than the range rover (remember nothing like the RR existed so they didn't know how it would sell) they built it more with the 101 in mind. i know the 101's were built from 1975-78 but they had been developed alot earlier than this. constant 4wd came from the fact that they didn't want big heavy axles on the RR so to split the toque to front and rear this was done. even rover knew how week there diff/axles were as they did not want to risk 135hp and 205ft/lb toque on the rear only. ha. any way the first RR had a 1st low of 47.84-1 with 3.54 axles, the 101 had 75.11-1 with 5.57 axles, so this is the difference, the axles. they both had high range of 1.174-1 and low of 3.321. remember in the RR from 1976 they started to change the transfer ratios in high range first. 1.116-1 then in 1981, 0.996-1 low was not effected.
cheers, serg

[uninformed]

just to correct myself, YES they were different as the transfer box was integeral to the lt95, so in 1976 and 81 you had different high range. this would help road driving on the 101's so 4th high was 6.54, it would become 1976=6.21 and in 1981=5.55
cheers, serg

[LowRanger]

according to my genuine workshop manual,it lists the following for the LT95.

Fourth 1:1
Third 1.505:1
Second 2.448:1
First 4.069:1
Reverse 3.664:1

Transfer ratios

Gearbox suffix A&B,.......... C............ *............. **

............. High 1.174:1.. 1.113:1.. 1.123:1.. 0.996:1

............. Low 3.321:1.. 3.321:1.. 3.321:1 .. 3.321:1


Overall Ratios

Gearbox suffix A&B......... C......... *.......... **......... Low

........Fourth 4.16:1.... 3.94:1.... 3.97:1.... 3.53:1.... 11.76:1

........Third 6.25:1.... 5.93:1..... 5.98:1.... 5.30:1.... 17.69:1

........Second 10.17:1.... 9.64:1.... 9.72:1.... 8.63:1.... 28.78:1

.......First 16.91:1.... 16.03:1.... 16.16:1.... 14.34:1.... 47.84:1

......Reverse 15.23:1.... 14.43:1.... 14.56:1.... 12.91:1.... 43.08:1


* Denotes Suffix C from gearbox No. 355 94060 C

** Denotes PREFIX 12C

Hope this clears up a couple of things at least

[justinC]

Maybe they ran out of the 1.003:1 on the day they built yours??? Surely the gear would have been replaced with a cross-drilled one when the mainshaft oiling problem was fixed though?

Mine definitely has the 1.003 ratio.

Very strange Ben, Yes the input gear was replaced when the gearbox was rebuilt the third time( The time when the bellhousing misalignment of 050" was rectified!), and the T/box has definately got a 1.213 sticker on it.
I had heard these were supposed to have 1.003 gears, and was suprised to find mine without .
What RPM do you get at 100kmh in top with 750/16?
regards JC

[red90]

Hey all, i was at maxi-drive the other day and mal had a r380 apart, so i asked about 1st gear not being as low as the lt77 and he seemed to think the tdi was and the v8 wasn't. so we did a tooth count.
Main gear box
Primary 33/22 = 1.5
Low 13/32 = 2.46

1.5 x 2.46 = 3.69

Hmmm, now I wonder if I made an error. The data that I posted for the R380 was from a Discovery workshop manual, which I don't have anymore. Could someone with a Disco manual lookup the posted ratios. The newer Defender manuals that I have do not post ratios. Silly Land Rover.

Anyone want to go and count teeth on a Defender TDI R380?? Could you give Mal a call while the box is in pieces??

[uninformed]

hey John, it seems no matter how many books we quote and how many tooth counts we do, there will always be an exception to the rover rule. i think the box mal had apart was from a defender. i know it was a tdi. as i said he thought there was a tdi ratio and a disco v8 ratio. as for my lt95 ratios i got them from Graham Robson's The Range Rover Land-Rover, fully revised & up-dated edition1998 other info i have from The Land Rover Experience, Tom Sheppard. i only have s11a workshop manuals so i can't offer any help from them. when i asked my LR mechanic, Ricks 4WD, he looked up on his computer (lots of rover files) but could not find the ratios for defender tdi r380.
serg