I have a 3-speed auto tranny and I hate it!!!

[thissnsooosucks]

Just took home my very first Datsun! 1978 620 L20B, 3N71 3-speed bullshit transmission. I love it except the tranny part. It won't do. Especially if I plan to make this my daily driver (minimum 80 miles a day)

 

So.... 2 questions:

 

1) Does anyone have a 5-speed transmission they can sell me? I read the 200SX drops right in (clarify?)

 

2) Can anyone in the Los Angeles area install this for me??? I'll pay you!

 

My back has been injured and I can't do any strenuous work. I basically have an old man's back on a 29 year old body. Ironically, I work in a steam plant. :mellow:

 

I'm totally worthless when it comes to cars. But I've always loved Datsun and I really need my car to work for work. So please, help! Or suggest me to someone who can help. Thanks guys!

[Wide14u]

what is this no pics j/k but i do want to see it

[datzenmike]

The very early '72-'73 620 had a short length transmission and the '77-'79 200sx would fit without having to mod the drive shaft. After Oct '73 a longer 4 speed was used. In '77 the 620 had a 5 speed option the same length. Fortuitously the 280z/zx also uses the same length transmission as does the 810/Maxima. These would be good candidates.

 

If you have a bad back why would you want to work a clutch and gear shift? The auto is perfect. This is a major cost in labor to have someone else do this for you even if the parts, all the parts, were available and free. If this is a mileage or problem with high rev sounding motor you could much easier change the rear end to a 4.11.

 

You will need clutch and brake peddles,any nuts, bolts, springs and switches. A clutch master cylinder (new preferably) and push rod, clutch slave (new preferably) and a hard line between them. A flex line from the slave and tranny. A five speed transmission, hopefully with clutch arm, boot, shifter and boot included. A 225mm flywheel, matching clutch disc and pressure plate (new preferably), pilot bushing for the crank, release bearing and collar. I think you can 180 the automatic X member and use the rubber mount from the auto. You may have to mod the tranny cover plate in the floor to fit the new shifter location.

[thissnsooosucks]

The very early '72-'73 620 had a short length transmission and the '77-'79 200sx would fit without having to mod the drive shaft. After Oct '73 a longer 4 speed was used. In '77 the 620 had a 5 speed option the same length. Fortuitously the 280z/zx also uses the same length transmission as does the 810/Maxima. These would be good candidates.

 

If you have a bad back why would you want to work a clutch and gear shift? The auto is perfect. This is a major cost in labor to have someone else do this for you even if the parts, all the parts, were available and free. If this is a mileage or problem with high rev sounding motor you could much easier change the rear end to a 4.11.

 

You will need clutch and brake peddles,any nuts, bolts, springs and switches. A clutch master cylinder (new preferably) and push rod, clutch slave (new preferably) and a hard line between them. A flex line from the slave and tranny. A five speed transmission, hopefully with clutch arm, boot, shifter and boot included. A 225mm flywheel, matching clutch disc and pressure plate (new preferably), pilot bushing for the crank, release bearing and collar. I think you can 180 the automatic X member and use the rubber mount from the auto. You may have to mod the tranny cover plate in the floor to fit the new shifter location.

 

Thanks, Mike. I completely didn't think about the strain of driving stick. It's been so long since I have.

 

And you pretty much nailed the reason why I don't like this 3-speed auto... I'm having a terrible mileage problem with the high RPMs. I just drove 40 miles and burnt up about half a tank of gas on a heavy foot. :unsure:

 

So to get this straight, I could change my rear end differential to a 4.11 and essentially change my engine RPMs for better mileage? How does that translate in what I'll rev at in 1st, 2nd and 3rd gear? (I'll be doing mostly freeway driving) Right now, it appears that my gears change at 30 and 60 mph. I don't have a tach, so I don't know what RPM it's shifting at.

 

Sorry if I sound completely aloof, but like I said, auto-mechanical work is not my deal :(

[thissnsooosucks]

Sorry... here's a pic.

[dat77sun]

Sorry... here's a pic.

 

clean truck, what brand are the seats?

[thissnsooosucks]

Not sure. Something generic.

[datzenmike]

Thanks, Mike. I completely didn't think about the strain of driving stick. It's been so long since I have.

 

And you pretty much nailed the reason why I don't like this 3-speed auto... I'm having a terrible mileage problem with the high RPMs. I just drove 40 miles and burnt up about half a tank of gas on a heavy foot. :unsure:

 

So to get this straight, I could change my rear end differential to a 4.11 and essentially change my engine RPMs for better mileage? How does that translate in what I'll rev at in 1st, 2nd and 3rd gear? (I'll be doing mostly freeway driving) Right now, it appears that my gears change at 30 and 60 mph. I don't have a tach, so I don't know what RPM it's shifting at.

 

Sorry if I sound completely aloof, but like I said, auto-mechanical work is not my deal :(

 

Hell you could probably go much lower like 3.889 or 3.70 for a light truck like that out on the highway. Shifts at 30 and 60 must be be full throttle. naturally a 3.889 ratio will slow down the acceleration but the higher 4.375 is fro a truck hauling half a tom load in the back. Since this is for transportation only you can do away with some of the gearing. My '78 would get high 20s on long trips so I'm guessing the auto would be at least 25 or a bit more. Going from 4.375 down to say 3.889 is a 12% drop in engine RPMs.

 

There comes a point where the engine RPM's drop so much that there isn't enough power to push through the air and the throttle is pushed down more and more and there is little to gain.

 

Keep in mind that to double your speed you need 4 times as much power not twice. This means that to go 80 you need 4 times what is needed to go 40. A small drop in speed makes a huge difference in mileage. People used to speed find the discipline very hard to go the speed limit.

Keep your tires inflated to the max pressure on the sidewalls. It will roll easier and save gas. The ride will be firmer though.

Town stop and go is the worst. Remember every time you hit the brakes you are throwing away the gas just used to accelerate the weight of the truck up to speed. Anticipate slow downs and stops well in advance and let the truck slow down under it's own momentum.

[thissnsooosucks]

Hell you could probably go much lower like 3.889 or 3.70 for a light truck like that out on the highway. Shifts at 30 and 60 must be be full throttle. naturally a 3.889 ratio will slow down the acceleration but the higher 4.375 is fro a truck hauling half a tom load in the back. Since this is for transportation only you can do away with some of the gearing. My '78 would get high 20s on long trips so I'm guessing the auto would be at least 25 or a bit more. Going from 4.375 down to say 3.889 is a 12% drop in engine RPMs.

 

I appreciate the straight forward answers, they're very helpful.

 

Even not at full throttle, I can feel the car reving at at least 4-6000RPM and still not changing gears. I feel on edge waiting for it.

 

I don't mind a slower acceleration since this is going to be a commuter car.... for now. You have any idea how much this should cost me or if any import auto mechanic can do this?