Series Gearbox ID

**Slunnie** · 13th July 2012, 01:22 AM

My eyes have gone square googling and reading info on identifying series gearboxs. This info comes from quite a few sources.

Please tell me if there is an error.

There are 3 types of gearbox: Series I & II, Series II and Series III.

Series I & II
· Serial Number with no suffix.

Series IIa
· Serial number on the RHS of the gearbox with a suffix underneath the serial number.
· Non synchro 1st & 2nd gears, synchro on 3rd & 4th gears.
· Very late (from early 1971) gearbox had synchro on all gears - gearboxs stamped with an "S" prefix. "S" may also be stamped on a top cover.
· Clutch slave on RHS and vertical on a Series IIa Bellhousing. (Suffix B+ may also fit Series III Bellhousings)
· Suffix B+ are renowned for being the strongest and/or most durable of the series gearboxs.
· Suffix: A/B -- C+
1st - 2.996 - 3.6
2nd - 2.043 - 2.22
3rd - 1.377 - 1.5
4th - 1.000 - 1.00
Rev - 2.547 - 3.02
High – 1.15 – 1.15
Low – 2.89 – 2.35

Series III
· Serial number with a following suffix on the top RHS flange of the transfer case.
· Synchro on all 4 gears.
· Clutch slave on LHS and horizontal on a Series III Bellhousing.
· Particularly the Suffix A & B require slow shifting to preserve the gearbox and have reduced strength and durability compared to the Series IIa gearboxs.
· 1st - 3.68
2nd - 2.22
3rd - 1.5
4th - 1.00
Rev – 3.02 or 4.02
High – 1.15
Low – 2.35

To tell the Series III box from the Series IIA without even having to drive it. Select all 5 gears (including reverse) noting the travel of the lever. If the lever moves about the same amount in all gears except 2nd, which is a lot less, it’s a Series IIA box. If the lever moves a long way in reverse, 3rd & top and not much in 1st & 2nd it’s a Series III box. It’s easy to check when driving. Drive at about 40-45 in 3rd, dip the clutch and go for 2nd. If it goes in silently it is a Series III, if it makes a horrible noise (and possibly won't go in) it’s a Series IIA. Alternatively, run the engine at a fast idle in neutral with the clutch engaged. Then dip the clutch and try engaging 1st gear. If it grates it’s a Series IIA. If it goes in silently after a moment’s resistance, it’s a Series III.

4cyl
Bellhousing - 1 top bolt at 12 oclock
2 bends in the gear stick

6cyl
Bellhousing - 2 top bolts at 11 and 1 oclock.
1 bend in the gear stick

For those with gearboxs with NO serial numbers, I would guess that a Series III gearbox has been mated with a Series IIa transfer box.

For those with gearboxs with TWO serial numbers, I would guess that a Series II or IIa gearbox has been mated with a Series III transfer box.

I'd be interested in any other input into the differences between these gearboxs.

**Lotz-A-Landies** · 13th July 2012, 03:38 AM

Hi Simon

The SIIa suffix D is actually the stronger boxes because of the change in the layshaft, where the circlip, retaining 2nd gear was removed and replaced with a shouldered layshaft.

The suffix B and later transfer boxes are more reliable than the Suffix a and SI/SII boxes because of the larger intermediate shaft diameter. The best low ratio crawler ratios are obtained by using a suffix c+ gearbox with a suffix B transfer ratio.

Also on the late SIII boxes the casing were reinforced with extra alloy (lattice shape) over the reverse idler shaft. The early SIII boxes were renown to crack in this location.

Can be seen on image below between red and green arrows.

**JDNSW** · 13th July 2012, 05:51 AM

Series 2 and 2a (except the very late all synchro box) have the clutch slave cylinder on the RHS of the bell housing, not LHS (in this country anyway - I haven't looked up to see where LHD ones have it).

All boxes have the same critical dimensions and are a direct replacement except for the bell housing being different between the six and the four cylinder boxes. But note that the clutch release sleeve is positioned differently, so that the pressure plate is different between the Series 1/2/2a and Series 3.

John

**pop058** · 13th July 2012, 06:53 AM

My 4/71 2A Workshop does not have syncro on 1st & 2nd. I am yet to confirm the box number.

**Slunnie** · 13th July 2012, 09:12 AM

Originally Posted by Lotz-A-Landies

Hi Simon

The SIIa suffix D is actually the stronger boxes because of the change in the layshaft, where the circlip, retaining 2nd gear was removed and replaced with a shouldered layshaft.

The suffix B and later transfer boxes are more reliable than the Suffix a and SI/SII boxes because of the larger intermediate shaft diameter. The best low ratio crawler ratios are obtained by using a suffix c+ gearbox with a suffix B transfer ratio.

Also on the late SIII boxes the casing were reinforced with extra alloy (lattice shape) over the reverse idler shaft. The early SIII boxes were renown to crack in this location.

Can be seen on image below between red and green arrows.

Thanks Diana! The increased webbing on the Series III gearbox is that shown between the 2 arrows???? Was this from Series III Suffix B onwards?

Also, I note that the green arrow is where I found the Series IIa serial number and the red arrow is where I found the Series III serial number.

Originally Posted by JDNSW

Series 2 and 2a (except the very late all synchro box) have the clutch slave cylinder on the RHS of the bell housing, not LHS (in this country anyway - I haven't looked up to see where LHD ones have it).

All boxes have the same critical dimensions and are a direct replacement except for the bell housing being different between the six and the four cylinder boxes. But note that the clutch release sleeve is positioned differently, so that the pressure plate is different between the Series 1/2/2a and Series 3.

John

Thanks for this John, great info! Absolutely correct and surprised I didn't pick this up re the Slave sides when looking at the gearboxs last night. I've just altered the first post to correct this.

**Lotz-A-Landies** · 13th July 2012, 09:31 AM

Hi Simon
The two arrows were indeed done to point out the number locations in a recent thread. The lattice wasn't present on suffix A SIII but was there by the time of the army contracts ?Suffix D SIII, but to find the actual change you'd have to find the service bulletin.

Hi John
Only in SI mechanical clutch linkages were different for LHD and RHD, in SII/SIIa with hydraulic system. the crossover was achieved by pipework. AFAIK this remained the same with SIII.

Diana

**JDNSW** · 13th July 2012, 09:51 AM

Originally Posted by Slunnie

Thanks Diana! The increased webbing on the Series III gearbox is that shown between the 2 arrows???? Was this from Series III Suffix B onwards?

Also, I note that the green arrow is where I found the Series IIa serial number and the red arrow is where I found the Series III serial number.

Thanks for this John, great info! Absolutely correct and surprised I didn't pick this up re the Slave sides when looking at the gearboxs last night. I've just altered the first post to correct this.

To further correct, or perhaps add to my post, the Series 1 (and 2l S2) petrol engines use the same bell housing as the six (Although I have an idea one stud is different), S1 and S2 diesel 2l are same as the 2.25 petrol and diesel fours.

John

**gromit** · 13th July 2012, 10:15 AM

Thanks guys,

This thread is helping me identify the gearboxes I have acquired and would be useful as a 'sticky' because there are lots of posts asking similar questions on Series boxes.

I found this on LandyZone
"Series 2A 1965-'72
Transmission Bearings & Seals; (Not inc transfer case)

Constant mesh pinon X1 RLS12/C3
Gearbox front seal (suffix H on) X1 35x50x10SLR
Primary pinion & Mainshaft Seal (sufix H on) X2 35x50x10SLR
Mainshaft Front X1 RA156 (NDH)
Mainshaft Rear X1 6307/C3
Mainshaft Rear Seal X1 193-300-50SLR
Layshaft Front (Suffix A) X1 RMS6/C2
Layshaft Front (Suffix B ) X1 6305/C3
Output Shaft Seal (F&R to '78) X2 162-250-50SSL
Output Shaft Seal (F&R '78 on) X2 162-250-50DLR
Speedo Pinion Seal X1 062-100-18SLR"

Short history here :-
Land Rover gearbox history

Gearbox suffix numbers here :-
Land Rover FAQ - Repair & Maintenance - Series - Chassis Numbers - Suffixes

Colin

**series3** · 13th July 2012, 04:20 PM

My 11/71 swb 2a has only 3rd and 4th synchro'd. (255 059 36F). I can only presume it's originality.

Sam

**Lotz-A-Landies** · 13th July 2012, 05:04 PM

Originally Posted by JDNSW

To further correct, or perhaps add to my post, the Series 1 (and 2l S2) petrol engines use the same bell housing as the six (Although I have an idea one stud is different), S1 and S2 diesel 2l are same as the 2.25 petrol and diesel fours.

John

To clarify John's post, the bolt pattern on the bellhousing to the flywheel housing/adapter on the 6 cyl Land Rover are essentially the same as S1 from 1954 model onwards. However the bellhousing on the gearbox on the S1 and SII 2 litre petrol have the small layshaft front bearing and matching clutch throwout housing, while the 6 cyl has the large bearing amd matching throwout.

BTW. as mentioned by Sam, I have never seen a genuine SIIa all synchromesh box and this accords with my Jan 1972 First Edition SIIa Parts Catalogue P/N 60824 which discusses the sealed pinion but not an all synchromesh box. Perhaps this was a NAS or UK Home market option that wasn't sold here.

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