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LT77 Gearbox Identification

Posted: Fri Sep 28, 2007 3:36 pm
by Coops
Gear box identification

the identification marks can be found on an oval lug near the base of the box

G16A SD1 2000 (Could be 4 speed)

G17A SD1 2300/2600 5 speed

G19A SD1 3500 SE/VP 5 speed

G22A SD1 3500 Police spec 5 speed

G23A SD1 2600 Police spec 5 speed

G26A SD1 2400 Diesel 5 speed

G27A SD1 2000 Later model 5 speed

G28A SD1 Vitesse 5 speed

G30A Sherpa Range

Posted: Tue Jan 15, 2008 6:39 pm
by paulmanta
Sorry about posting this in a nice tidy topic but i have what i suspect is an LT77 box, It looks the same as an LT77 i am fitting to my Manta but when i went to try and ID this box from the oval flat area by the drain plug i found that not only was the number not there but the machined area was missing too, it was just a plain casting from the factory, i can find no other numbers anywhere.

Any idea what i have here ?

Posted: Wed Feb 06, 2008 1:41 am
by V6GTE
Is the five speed box fitted to a TR7 an LT77? If so, with the correct bell-housing, would it be compatible with a Rover V8 engine?

Many thanks


Posted: Wed Feb 06, 2008 1:44 pm
by bodger
that what i was wondering , i have a TR7 box and sd1 bell housig and it looks like they are the same , they certainly fit together , and the TR7 clutch arm is the same as the rover one
not sure about ratio's , but as i have it all apart i'll count the teeth

Posted: Wed Feb 06, 2008 3:18 pm
by bodger
with the gearbox stripped and the clusters in situe ie:the input shaft pointing sky ward
working from the top

input ............. layshaft

22 ............. 33 = 4th / pinion gear
27 ............. 29 = 3rd
32 ............. 23 = 2nd
reverse .............
31 ............. 14 = 1st
20 .............. 36 = 5th
and 5th gear below the plate

it has the same ratios as an SD1 V8 box

to calculate the ratio's ..first divide the pinion gear ie: 33 / 22 =1.5
then divide the input shaft by the layshaft and multiply by the 1.5 ..and thats the ratio
1st gear
31 divided by 14 = 2.21 then times the 1.5 you got earlier and the result is 3.32 which is right

thankyou to Dave Ashcroft for explaining to me ... it makes sense now

or picture here :

Posted: Thu Feb 07, 2008 7:26 pm
by V6GTE
Cheers Bodger you are a star!

Posted: Thu Feb 07, 2008 7:52 pm
by paulmanta
Numbers stamped on the bottom of mine near where it joins the back nose casting, looking at the list it suggests its an SD1 police type. Nice !

Posted: Thu Feb 07, 2008 8:06 pm
by bodger
ssshhh don't tell everyone or they will be as expensive as SD1 boxes on ebay

havin stripped the tr7 box now , all the parts are the same as an SD1 box
inc oil pump / gaskets /seals and bearings
even the rear bearing is the same , even the LDV version that is suppose to have a stronger one is the same 6205 c3 bearing
change it everytime , each box i have stripped it's always noisy

Posted: Sun Feb 17, 2008 9:15 pm
by V6GTE
do'h :roll: I just read the 'gearbox' section of the Haynes manual for the Rover SD1 and it states in there that the box is the same as a TR7!

Posted: Thu Oct 16, 2008 6:40 pm
by topcatcustom
Does anyone know what ratio's i have in my 'box? The serial number is 28A0011412D and want to work out what ratio diff I need for the back - once I know what size wheels are going on!!!

Posted: Thu Dec 11, 2008 7:29 pm
by bodger
the only real differnence is the higher ratio 5th gear in your box TC , they all has the same ratios until the later versions ie vitesse which had a 37/19 5th gear pair
and also the sherpa version =R150-5 which had a completely differant primary ratio

Posted: Wed Nov 23, 2011 9:36 pm
by Richard P6
I have seen a couple of SD1 manual gearboxes which I presume are LT77s, but they have a serial number like CL-044564-C.

Anyone know what these are from?


gearbox ID

Posted: Tue Aug 27, 2013 10:51 pm
by asam_x
Hi. Can anyone give me any info on this box? Serial number is 28A0249247E. Thanx