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speedo problem

hi all please can someone help me out, I have a 1988 suburban R20 2wd truck with tbi and a th400 gearbox, my problem is the Speedo doesn't work, I have fitted a new cable,head and a brown 39tooth plastic gear, my question is does anybody have a diagram for a th4oo box so I can see what is involved in replacing the steel Speedo gear which drives the 39 tooth brown plastic one, the small governor gear is in good condition so the only thing left is the steel gear, any advice will be very welcome. thanks xxxxxl p.s I am in England so taking it to a transmission shop isn't easy in my area.

Reply to
xxxxxl
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first:

spin the cable at the lower end with a drill and see if it reads in the cab

if not, it's not the gear

is so, you have mis-matched parts

Reply to
TranSurgeon

Hi Transurgeon thanks for the advice, the head is genuine gm and so is the cable, the 39 tooth plastic gear was identical to the old one its teeth were in perfect condition but the shaft had snapped in half, the head needle was moving freely when I spinned it with my fingers prior to fitting. thanks xxxxxl

Reply to
xxxxxl

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