'81 720 Transmission removal

Dealing with all subsystems specific to the diesel powered Datsun-Nissan 720 pickup trucks.

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'81 720 Transmission removal


Post by FinnHillBilly »

I have a 1981 Datsun 720 SD22 standard cab with the regular (6.5 foot) bed, and for the second time I find myself in need of some transmission repairs. Last time I was able to locate one in a junkyard and I swapped them out, but because of the welded cross member I couldn't get enough clearance without raising the engine up about 6 inches or so. I rented a hoist before (I new I should have just bought one...) but I'm wondering if there was something obvious that I missed that would get it free without having to break the motor loose.

A call to the local transmission shop got me an estimate of $757 labor to remove, rebuild and reinstall the transmission, but you add in another couple hundred bucks (at a minimum) parts and I'm wondering if it's worth it for a trash hauler. If I could get the thing out and figure out just how far gone it is without spending an arm and a leg it might make it worth the trouble though.

I searched through the archives and came across a mention of it being a pain to R&R these, but no specifics. Anyway, if this has been covered in another thread that I missed by all means please point me in the right direction...

1981 Datsun 720 / SD22
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Post by asavage »

I've done it twice, but while it's a PITA, it doesn't require raising the engine.

From memory: The main thing is to remove the shift console (if equipped), the shifter boot, the entire floor plate (about 16" long, galvanized) and the shift lever (remove external snap ring or E-clip, remove cross shaft. Remove drive shaft assy. including carrier brg. Exhaust pipe has to be unbolted to allow some engine movement. Slave cylinder unbolts.

On the topic of rebuilding: while it's not my best writing, it's still good to read this thread to learn about the weak areas (two brgs, reverse gear) and cheaper alternatives to gears replacement if they are shot (gasser guts). By the time you get significant noise in 1,2,3,5 gears, and/or won't move, too many gears are shot to be worth rebuilding, and a used trans that was behind an SD is a poor investment unless you have driven it personally -- too many of them are bad!
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.
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Re: '81 720 Transmission removal


Post by philip »

FinnHillBilly wrote:SNIP - A call to the local transmission shop got me an estimate of $757 labor to remove, rebuild and reinstall the transmission, but you add in another couple hundred bucks (at a minimum) parts and I'm wondering if it's worth it for a trash hauler. -SNIP
It wasn't long after my 1982 aquistion (Feb '04) because ... it was given to me free. Well ... there's no such thing of "free" things and if you drive it ... it's not going to stay "free." LOL And like youself, this truck looked like it could be handy as a trash hauler and to grocery.

I'm older so I'm better at writing checks than I care to do heavy stuff myself. It ran about $650 for the whole thing including a new clutch. Luckly, I stopped the first day it suddenly started new making chatting noises ... so the gears were still good (enough). I watched the trans box dropped out WITHOUT moving the engine so ... follow as Al says.

Getting back to the "free." ANY vehicle this old and shakey as these little diesels are ... is going to request maintenances. If you accept that fact ... you'll sorta like these little critters. :wink:
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

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Post by abumariah »

I've done several transmissions...all dropped without the engine. IMO its worth the education the first couple times you do it even though it is a lot of work. Every time you shift after you rebuild it you'll be proud of yourself.

When it comes down to parts there are a couple places to look at for rebuild kits and someone on here will probably have any gears you might need for a small fee

I know I've got three old trannys with good gears around here somewhere...
1985 720 kc 4x4 z24
1981 720 kc 2wd sd22
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