LT77 Gearbox Identification

[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

[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 ?

[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

Ian

[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

[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
ie:
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 : http://www.putfile.com/pic.php?img=7626912

[V6GTE]

Cheers Bodger you are a star!

[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 !

[bodger]

ssshhh don't tell everyone or they will be as expensive as SD1 boxes on ebay ..lol

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

[V6GTE]

do'h 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!

[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!!!

[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

[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?

Richard

[asam_x]

Hi. Can anyone give me any info on this box? Serial number is 28A0249247E. Thanx

[V8BRI]

hi all
i have a lt77 ( G17A ) i read on here is from sd1 23/26 5spd
but i cannot get 5th gear, could it be a 4spd box ? or i got other problem

[richyb66]

It's more likely to be a problem that missing completely. G17A would indicate 5 speed but I wouldn't put it past BL to have got the wrong number on it. If you can see it look at the small oval plate on top of the box closest to the gear lever (retained by 2 bolts that are aligned along the length of the gearbox).

If the oval plate is a plain flat plate, then the box is 4 speed. If it has a round pin in the centre of it, it's the locating pin for the 5th gear spool in which case the problem is either knackered rubber bushes on the remote gearchange extension, or something else internal.