Keeper_of_Tess
Trekker
This is a guide to the main differences that I have found (by reading, and some doing, and by asking questions on this forum) between the 1 Ton gearbox and the "normal" LT76 for the Series III. Most idiots' guides are written for idiots. This one differs in that it was written by an idiot, which is why the position of the apostrophe in the title is correct. Treat the information herein with suitable caution.
I have included remarks on differences between the different gearbox suffixes because, of course, theses are relevant to 1 Ton owners too.
All of this information is available elsewhere, none of it is my original work. If you find a discrepancy between what I've written here and some other authority assume that I've got it wrong.
1 Ton vs non-1 Ton differences:
No, this isn't about Chinese soups.
The mistake that I made when I started stripping an unknown gearbox for a rebuild was to ignore the transfer box until the very end of the strip down. If you look at the WSM, page 37-14, section 37.29.28 it tells you how to decide if you have an all-helical gear transfer box, or a helical-and-spur transfer box.
I erroneously assumed that the all-helical was the standard, later, transfer box and that the helical-and-spur transfer box is an older, more simple design. I was wrong.
It seems that all normal gearboxes use helical-and-spur transfer boxes (WSM page 37-18 , section 37.29.28) and that if you have the all-helical flavour, you're looking at a 1-Ton gearbox, like mine.
The main points are that the inner gubbins in the transfer case are radically different. The parts on the mainshaft that interface with the transfer box are very different. The overall gearing on the 1 Ton gearbox assembly is lower than for normal models; and ordinary overdrives, and high-ratio transfer gear sets, cannot be used to achieve a higher gearing.
So, really, the only folk who would want a 1 Ton gearbox are people who want to rebuild a 1 Ton.
Different Series III Gearbox Suffices:
In essence, suffix A boxes have a few of their own quirks.
Suffix B and C gearboxes are pretty much of a muchness except that during suffix C, the layshaft design changed while, unhelpfully, retaining the same part number.
suffix D gearboxes moved over to ECM gears, which are supposed to be stronger.
You cannot put ECM gears in with an early layshaft.
You can put ECM gears in a late suffix C gearbox, if you also change the 1st/2nd selector shaft. The WSM explains all of this on page 37-20, and tells you how to determine what kind of layshaft you have.
I believe that it is possible to up-rate earlier gearboxes to use a late-type layshaft but it's beyond my competence. I mention this because you might find yourself working on an apparently early gearbox that has been up-rated to D specification by a gearbox specialist.
There now follows a walk through the parts manual, looking at the important differences that I've been able to find. The reference numbers refer to the original microfiche pictures, from the parts manual.
Bell Housing
1H 02 1RE 110
No significant differences apart from the 2.6 petrol version, which uses a different bell housing.
************************************************
Front Cover
1H 03 1RE 111
All the same
************************************************
Main Casing
1H 03 1RE 109
Suffix A gearboxes use a different casing to all others
Minor changes in drain plug from some D-suffix boxes onwards
************************************************
Primary Pinion
1H 04 1RE 164
No difference between 1 Ton and "standard" versions. However, the gears changed from suffix D onwards. The primary pinion / constant gear assembly and the 3/4 synchro for pre-D and D-onward ECM gears are different and are not interchangeable.
606880 primary pinion. Use RTC2684 from suffix D onwards
FRC1758 3/4 synchro. Use FRC6996 from suffix D onwards
************************************************
Mainshaft
1H 04 1RE 164 & 1H 04 1RE 165
See remarks regarding D and pre-D gears above. As far as 1 Ton vs standard gearbox differences are concerned, different mainshafts are used and many of the rear mainshaft components differ too.
From the rear end forward....
576725 mainshaft 1 Ton uses 576726
217477 castellated nut 1 Ton uses 521633
217476 locking tab washer 1 Ton uses 521634
501501 washer 1 Ton uses 521636
218244 mainshaft gear 1 Ton uses 522017
502482 distance piece 1 Ton uses 521852
232415 oil thrower - an alternate part (FRC5116) is used for the transfer box deployed with late-D gear boxes.
236305 oil seal - same
RTC1948 circlip - same
FRC5115 bearing housing - same
1645 bearing - same
9960 circlip - same
576735 thrust washer -same
576734 bush -same
591362 mainshaft first gear: for suffix C boxes, use FRC2056; for suffix D, FRC3201
591364 synchro cone - same
608283 inner+outer member: for suffix B & C, use RTC2195; for suffix D, RTC2685
553084 }
503805 } plates, springs, ball bearings. All the same.
BLS108L }
RTC1979 pin - same
6405 pin - same
591364 synchro cone - same
267572 thrust washer - same, choose 267572 to 267575 as required for thickness
591363 2nd gear - same for 1 Ton. Use FRC2673 from suffix D onwards
FRC4076 bush - same
FRC4077 bush - same
556010 3rd gear - same for 1 Ton. Use FRC8179 from suffix D onwards
RTC1962 washer - same. Use 50702 or 50703 if greater thickness needed.
RTC1957 circlip -same
6397 bearing - same
************************************************
Layshaft Gears and Reverse
1H05 1RE 167 & 1H05 VS1 043
No differences between the "standard" and "1 Ton" versions.
However, suffix A gearboxes use substantially different parts to the others,
suffix B uses a unique layshaft cluster (FRC1691)
suffix C onwards use layshaft cluster FRC2084
See remarks in the preamble regarding layshaft changes during suffix C production.
Suffix A gearboxes may have been fitted with a reverse gear modification kit.
************************************************
Intermediate Gear
1H 07 1RE 113 & 1H 07 5RE 167
The only difference I can see is that the gear cluster changes for 1 Ton models.
533080 intermediate gear cluster fits everything except 1 Ton variants.
539828 is for the 1 Ton gear box.
************************************************
Output Shaft
1H 07 1RE 113, 1 H 07 5RE 167, 1H 08 1RE 114 & 1H 08 5RE 168
Apart from the speedometer drive components, there are virtually no parts which are interchangeable between the normal and the 1 Ton versions.
************************************************
Transfer Case
1H 09 1RE 115
As far as I can tell, the transfer cases are all the same, despite the different internals. The only variation appears to be that the transfer case was altered during suffix D production and late D variants have different bottom plates and drain plugs
************************************************
Rear Mainshaft Bearing Housing
1 H09 1RE 116
1 Ton and normal gearboxes use different bearings and a different housing. There do not seem to be any suffix-dependent variations, however.
************************************************
Front Output Shaft and Housing
Parts all look to be interchangeable between suffixes and from normal variants to 1 Ton gearboxes, with the exception of the dust cover and its fixings.
The standard part is 266956 but the 1 Ton uses a 512760 dust cover.
************************************************
I hope this helps someone else. Please feel free to point out ant errors or omissions, for which I apologize in advance.
Kind wishes,
Nick
I have included remarks on differences between the different gearbox suffixes because, of course, theses are relevant to 1 Ton owners too.
All of this information is available elsewhere, none of it is my original work. If you find a discrepancy between what I've written here and some other authority assume that I've got it wrong.
1 Ton vs non-1 Ton differences:
No, this isn't about Chinese soups.
The mistake that I made when I started stripping an unknown gearbox for a rebuild was to ignore the transfer box until the very end of the strip down. If you look at the WSM, page 37-14, section 37.29.28 it tells you how to decide if you have an all-helical gear transfer box, or a helical-and-spur transfer box.
I erroneously assumed that the all-helical was the standard, later, transfer box and that the helical-and-spur transfer box is an older, more simple design. I was wrong.
It seems that all normal gearboxes use helical-and-spur transfer boxes (WSM page 37-18 , section 37.29.28) and that if you have the all-helical flavour, you're looking at a 1-Ton gearbox, like mine.
The main points are that the inner gubbins in the transfer case are radically different. The parts on the mainshaft that interface with the transfer box are very different. The overall gearing on the 1 Ton gearbox assembly is lower than for normal models; and ordinary overdrives, and high-ratio transfer gear sets, cannot be used to achieve a higher gearing.
So, really, the only folk who would want a 1 Ton gearbox are people who want to rebuild a 1 Ton.
Different Series III Gearbox Suffices:
In essence, suffix A boxes have a few of their own quirks.
Suffix B and C gearboxes are pretty much of a muchness except that during suffix C, the layshaft design changed while, unhelpfully, retaining the same part number.
suffix D gearboxes moved over to ECM gears, which are supposed to be stronger.
You cannot put ECM gears in with an early layshaft.
You can put ECM gears in a late suffix C gearbox, if you also change the 1st/2nd selector shaft. The WSM explains all of this on page 37-20, and tells you how to determine what kind of layshaft you have.
I believe that it is possible to up-rate earlier gearboxes to use a late-type layshaft but it's beyond my competence. I mention this because you might find yourself working on an apparently early gearbox that has been up-rated to D specification by a gearbox specialist.
There now follows a walk through the parts manual, looking at the important differences that I've been able to find. The reference numbers refer to the original microfiche pictures, from the parts manual.
Bell Housing
1H 02 1RE 110
No significant differences apart from the 2.6 petrol version, which uses a different bell housing.
************************************************
Front Cover
1H 03 1RE 111
All the same
************************************************
Main Casing
1H 03 1RE 109
Suffix A gearboxes use a different casing to all others
Minor changes in drain plug from some D-suffix boxes onwards
************************************************
Primary Pinion
1H 04 1RE 164
No difference between 1 Ton and "standard" versions. However, the gears changed from suffix D onwards. The primary pinion / constant gear assembly and the 3/4 synchro for pre-D and D-onward ECM gears are different and are not interchangeable.
606880 primary pinion. Use RTC2684 from suffix D onwards
FRC1758 3/4 synchro. Use FRC6996 from suffix D onwards
************************************************
Mainshaft
1H 04 1RE 164 & 1H 04 1RE 165
See remarks regarding D and pre-D gears above. As far as 1 Ton vs standard gearbox differences are concerned, different mainshafts are used and many of the rear mainshaft components differ too.
From the rear end forward....
576725 mainshaft 1 Ton uses 576726
217477 castellated nut 1 Ton uses 521633
217476 locking tab washer 1 Ton uses 521634
501501 washer 1 Ton uses 521636
218244 mainshaft gear 1 Ton uses 522017
502482 distance piece 1 Ton uses 521852
232415 oil thrower - an alternate part (FRC5116) is used for the transfer box deployed with late-D gear boxes.
236305 oil seal - same
RTC1948 circlip - same
FRC5115 bearing housing - same
1645 bearing - same
9960 circlip - same
576735 thrust washer -same
576734 bush -same
591362 mainshaft first gear: for suffix C boxes, use FRC2056; for suffix D, FRC3201
591364 synchro cone - same
608283 inner+outer member: for suffix B & C, use RTC2195; for suffix D, RTC2685
553084 }
503805 } plates, springs, ball bearings. All the same.
BLS108L }
RTC1979 pin - same
6405 pin - same
591364 synchro cone - same
267572 thrust washer - same, choose 267572 to 267575 as required for thickness
591363 2nd gear - same for 1 Ton. Use FRC2673 from suffix D onwards
FRC4076 bush - same
FRC4077 bush - same
556010 3rd gear - same for 1 Ton. Use FRC8179 from suffix D onwards
RTC1962 washer - same. Use 50702 or 50703 if greater thickness needed.
RTC1957 circlip -same
6397 bearing - same
************************************************
Layshaft Gears and Reverse
1H05 1RE 167 & 1H05 VS1 043
No differences between the "standard" and "1 Ton" versions.
However, suffix A gearboxes use substantially different parts to the others,
suffix B uses a unique layshaft cluster (FRC1691)
suffix C onwards use layshaft cluster FRC2084
See remarks in the preamble regarding layshaft changes during suffix C production.
Suffix A gearboxes may have been fitted with a reverse gear modification kit.
************************************************
Intermediate Gear
1H 07 1RE 113 & 1H 07 5RE 167
The only difference I can see is that the gear cluster changes for 1 Ton models.
533080 intermediate gear cluster fits everything except 1 Ton variants.
539828 is for the 1 Ton gear box.
************************************************
Output Shaft
1H 07 1RE 113, 1 H 07 5RE 167, 1H 08 1RE 114 & 1H 08 5RE 168
Apart from the speedometer drive components, there are virtually no parts which are interchangeable between the normal and the 1 Ton versions.
************************************************
Transfer Case
1H 09 1RE 115
As far as I can tell, the transfer cases are all the same, despite the different internals. The only variation appears to be that the transfer case was altered during suffix D production and late D variants have different bottom plates and drain plugs
************************************************
Rear Mainshaft Bearing Housing
1 H09 1RE 116
1 Ton and normal gearboxes use different bearings and a different housing. There do not seem to be any suffix-dependent variations, however.
************************************************
Front Output Shaft and Housing
Parts all look to be interchangeable between suffixes and from normal variants to 1 Ton gearboxes, with the exception of the dust cover and its fixings.
The standard part is 266956 but the 1 Ton uses a 512760 dust cover.
************************************************
I hope this helps someone else. Please feel free to point out ant errors or omissions, for which I apologize in advance.
Kind wishes,
Nick
