Tranny swap

[pickleweasle]

Whats up guys! Sorry im sure theres tons of post about this but I havent found any that are straight forward. I have a 79 620 king cab with an auto tranny that i want to swap to a 5 speed. From what all i've read a 280z tranny will work but im not 100% on that and i dont want to drop the cash on it and run into problems. If someone can tell me what cars/trucks I can get a tranny from year, model, and any other usefull info that would be awesome. I also need to know what flywheel I can use. Also too what mods need to be made to the body to make the swap work I assume that there are provisions for the clutch master cylinder and all i'll need to do is cut out for the shifter.

[datzenmike]

The 5 speed came in many years and models with a variety of different internal gear ratios. All will work, not saying they won't.

 

Vehicles that have the L series FS5W71B 5 speed that will bolt into your truck are:

 

'77-79 620

'80 2wd 720 (check that it is 31.5" long and not 26")

'78-'80 810

'81-'84 Maxima gas and diesel

'77-'78 280z and '79-'83 280zx non turbo.

 

You can use any 6 bolt flywheel. They come in 3 sizes 200mm, 225mm, and 240mm. They all look alike so to tell apart measure across the friction face like this one. It's a 240mm.

 

Trucks generally run a 225mm flywheel and the flywheel determines the clutch (225mm) size. This is about the second strongest clutch/pressure plate assy. Car L20Bs tend to use the 200mm flywheel. If you find one you can use the 200mm Roadster pressure plate a clutch disc. It's the strongest but very stiff to operate, so keep this in mind. Which ever size you get, be sure to get the matching release bearing holder. It is sized to match the size of the clutch you put in so if one comes with the tranny don't use it unless you get the flywheel that it was used with it.

 

To complete your swap you will need a clutch and brake peddle and all springs and mounting hardware from a standard 620 truck. Also:

 

The clutch master cylinder and push rod connecting it to the clutch peddle.

The clutch slave cylinder, there may be one already mounted to the 5 speed you buy.

A hydraulic hard line connecting the two and a flex line from body to slave. Pre made metric brake lines should work, bend them yourself.

A clutch arm and dust boot, may have one on the transmission you get.

A shifter, may be one on the tranny.

A brand new release bearing, spend the money, you don't want to have to take out the tranny again to replace it later. The bearing comes dry so it must be packed with grease.

A $5 pilot bushing to press into the end of the crankshaft for the nose of the 5 spd to fit into.Note: all automatics come with a spacer plate between the automatic flex plate and the crankshaft. It must be removed or flywheel won't fit on.

 

 

 

 

 

 

 

 

 

 

 

 

 

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[pickleweasle]

AWESOME thanks man thats everything I needed to know. I was just looking for a more common vehicle to get the tranny from and that helped alot. I will prob go with the 225 mm clutch setup cause I don't plan on building the engine alot at all so that should be fine. Thanks again for all the info!

[datzenmike]

You're welcome.the 5spd will have a reverse light switch about mid way up the side just behind the clutch arm dust boot. You will have to find the wires used on the automatic and wire it in.

 

Also the automatic has a safety NEUTRAL/PARK switch and an inhibitor relay to prevent starting it in gear. I can't remember if unplugging this or not using it as with the 5 speed will allow you to start or not. At worst two wires must be joined so the ignition 'thinks' it's in park and will start.

 

There is also a small vacuum line to the automatic that you don't need. It is usually spliced into the brake booster hose just before the one way valve and goes down behind the motor. Find and plug it.

 

When you disconnect the speedo cable, remove the speedo drive pinion in the tail stock once the tranny is out. This pinion is mated to your rear end gear ratio. The 5 speed may be out of a car with a totally different rear ratio. If your new 5 speed has the mounting bolt for the pinion in the twelve oclock position like this:

 

 

You should be able to slip the one from the automatic in and your speedometer will remain accurate.

.

[LenRobertson]

Datzenmike covered all the important things. I'll add a couple of links to pages of tranny ratios:

 

http://www.datsuns.com/Tech/datsun_transmissions.htm

 

http://newprotest.org/projects/510/gearRatios.pl

 

I've seen it alleged that 4-cylinder engines aren't happy with the Z trans with the 3.062 1st gear. It is supposed to be too high a ratio for comfortable standing start. I don't have any personal experience, just repeating what others say. It does appear the "Truck #1, #2, #3" trans on the second page have lower 1st gear. It might make a difference if you haul heavy loads in your 620 or not.

 

Note, some of the trannys listed on these pages are short-tailed (26" length), which you can't use without lengthening your driveshaft, and the Z20, Z22, and CA ones have a different tilt to the bellhousing. Either you swap bellhousings with an L 5-speed, of bend the shift lever to compensate for the tilt. Probably finding a "Truck", Maxima, or 280Z/early ZX box will be your best bet. But someone who has done it may post and say the later 280ZX works fine in a 620.

 

Len

[Dime Dave]

Old pilot bushing removal tip. (No fancy internal puller needed.)

 

Get a wooden dowel the diameter of the bushing ID (sand to fit if needed). Make sure it is a fairly snug fit, but not so tight it will get stuck.

 

Get your grease gun and fill up the inside of the old pilot bushing while it is in the crankshaft.

 

Take your dowel, push it into the ID of the bushing until it bottoms on the grease and wack it a couple times with a hammer. The bushing will be forced out by the grease. If grease is shooting out around the dowel and the bushing isn't moving, you need a bigger dowel that fits tighter in the bushing. (Like you haven't heard that one before!)

 

My Dad told me this trick and I didn't beleive him, but it works slick!

[74datsun620]

I use a cut Datsun transmission shaft to remove the pilot bushing with grease and a hammer. Also used for clutch alignment tool.

 

 

[datzenmike]

Pack with Ivory soap is cleaner but I just use a chisel or screwdriver blade and a hammer. Three slices or less down the length and the chunks will fall out.