- Don't unscrew the large 22mm nut on the top/driver side of the transmission. It's NOT the oil filler nut. It's really the pivot bolt for the shifter arm that controls reverse. If you take it out it disconnects the arm and drops a circlip into the bottom of the trans. You have to completely open the trans case to reset everything. I found this out by mistake, even after reading not to do it on a newsgroup. Stupid is as stupid does.
- If you do have to open the case, take off the shifter, and drive a pin out of the main shifter rod and slide off the rear housing after removing 8 large bolts around the housing. This allows you to take the top cover off the trans and remove the shifter to expose the gears.
- 75/90 has a lot of additives and cushions the gears and synchros well, but gets thick in cold temperatures.
- ATF (10W) is used to give quicker shifting and gear engagement, and makes cold weather shifting easier.
- on 1970 style bodies they came with a one-piece unit with a single hole in the center, with 1 vertical bolt on each side into the frame.
- On later 240-280's they were a heavier two-piece mount with 1 horizontal rubber bolt/bushing on either side.
BORG-WARNER T5 5-SPEED
280ZX
Yes a real Borg-Warner 5-speed came in the turbo 280ZX. It arrived at the end of the L28's life, when hydraulic heads, CV axles, and engine management systems were coming on the scene. It's a first generation Borg-Warner T5 like the ones in early 1980's Mustangs while the bell housing was replaced with a special Nissan version to let it fit onto a L6 motor. I remember in 1982 a mechanic at Bob Bell Datsun in Salem, Va told me that Datsun was worried a stock 5-speed wouldn't hold up which is why the 1981 turbo only came with an automatic.
While this isn't the "world class" T5 you find in late '90s cars, people have been racing Mustangs with them since the early 1980's with great results. The shorter 1st and 2nd gears of this model are slanted towards helping a turbo engine off the line, I believe this was rated to take 265 ft/lbs of torque which is fine for a 6-cylinder. I don't believe it came in the 2+2 ZX turbo as the driveshaft would have been a monster and 2+2's were usually automatic trans cars. But there might be some rare ones out there.
Borg-Warner doesn't make T5 transmissions anymore and gets annoyed if you call them with questions. They even used to have an angry disclaimer on their web site directing people to Tremec, who bought all the rights to the T5 in the 1990s. Unfortunately Tremec isn't much help either. Their response to a question was to suggest I go to my local transmission shop for help. I guess they bought the rights to the name, but nothing else.
I've compared the input shaft and I don't see any way to mate this with a Chevy or Ford V8. The input shaft is a different length, has a different pilot diameter, and a different number of splines for the clutch. In other words, nothing will easily transfer over to a V8. Even if you got a clutch to fit you would still need to buy an expensive new V8 bellhousing, so I wouldn't even try. Do yourself a favor and buy the proper T5 if you want to do a V8 conversion.
TRANSMISSION TIPS
BUT BE CAREFUL: I always thought I could R&R any engine part, but just learned differently. A T5 is a different beast, don't open it up unless you are trans-literate. The gears and synchros are held in place by two shifter forks coming out of the top housing. These shifter forks are controlled by some odd, sliding levers that have to be perfectly positioned. If you get them out of place it's nearly impossible to get them back unless you have a T5 rebuild manual to refer to.
I unknowingly messed them up on mine, and when I bolted everything back up the shifter wouldn't move. @#$%*. Luckily it was still out of the car and I knew an old guy at a local trans shop who was a T5 Guru. He took it home with him, reset everything, regasketed it and proclaimed it in excellent shape. I had to pay $100, but at least it got a clean bill of health and knew it was adjusted properly.
SHIFTER CHOICES
The Nissan T5 came with a poor-quality shifter, it's simply a straight rod out of the top of the trans.
FORD SHIFTER: Over the years Ford perfected the T5 shifter, the late 90's Ford Mustang shifter being the one to use on a T5. The dogleg angle greatly improves leverage and shifting feel. It also has a hard rubber damper that cuts down on buzziness. The only downside is that when in 1st, 3rd and 5th gears the shifter arm sits about 2 inches forward of the stock one on a first generation Z. This means you will need to modify the front of the console a bit. However, it improves shifting, smoothness, and overall drivability by such a huge amount it's worth the trouble.To find a stock Mustang shifter go to Ebay. You can sometimes find people who have upgraded their Mustang and need to get rid of the old stock shifter.
THE BETTER SOLUTION: As good as the Mustang shifter is I recommend getting a true "short-throw" version. Be careful though, there are several very cheap knockoff T5 shifters on Ebay and the internet: B&M and Summit Racing are the ones to use. The Summit version has a nice fat arm with cool gated spring action from side to side and the baseplate is solid aluminum. I have it on my T5...feels like a Formula 1 car now, very solid and fast, a major improvement over the excellent Mustang shifter....no kidding!
 Nissan vs. 2000 Mustang shifter |
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CLUTCH
The T5 came with a L6 Nissan 2+2/turbo clutch and respective flywheel. Interestingly, while the turbo and coupe flywheels are identical in weight (23 lbs), the turbo clutch cover is measurably heavier. It's much stouter, with thicker fingers and metal case, and sits higher. So I suspect using a turbo clutch adds unwanted weight and inertia to the engine. On my T5 I use the widely available "Zoom" brand coupe clutch (after changing the throwout bearing collar from 2+2 back to a coupe version) with no problems .
LUBRICANT
I'm not sure what the factory put in mine. The oil smelled like gear oil, but was very thin. The Datsun manuals don't say anything about T5 maintenance though, they seem to have forgotten to include it. I suspect Nissan shipped theirs with 75/90 weight. So I called the Pennzoil 800# number from their website, and also spoke to the local T5 guru who fixed mine. Both said that the trans specs call for 75/90 gear oil or ATF.
This T5 lore may be why some people use ATF in normal Z transmissions. But I don't think that's wise: 1970's transmissions are designed for a heavier oil to cushion the brass synchros and gears. The T5 can use ATF because it was designed to, not because the oil is superior.
Dexron-3/Mercon ATF came out in 1996. Before that there was Dexron 2 and before that Dexron 1. As they evolved the detergent and lubricating properties greatly increased over the years, making ATF an excellent oil. There are several ATF versions though, make sure you don't get "Type F" or "ATF+3". "Dexron-3/Mercon" is what you want. All brands have to meet the same standards to say Dexron3/Mercon, so the brand is up to you. I use synthetic-blend Valvoline ATF.
A Ford Muscle Web article claims 75/90W ruins world class T5s. This is because T5 oil passages and bearing clearances supposedly are smaller than regular transmissions, and a heavier gear oil can have trouble flowing through.
DRIVESHAFT (the tricky part in a 1st generation Z)
The Nissan T5 came with a special driveshaft to fit the 280ZX. It is stouter and fatter than other Z driveshafts, has a different spline count on the front end, and a square flange on the rear. In other words, the only driveshaft that will fit the T5 is the one that came with it. A 240/260/280 driveshaft cannot be modified to fit.
LENGTH: The T5 driveshaft is almost the same length as regular Zcar driveshaft, but the T5 transmission is a few inches longer. This means if you use a Nissan T5 trans/driveshaft in a first generation Z the driveshaft will be too long by about 2-3 inches.The solution is to have a custom driveshaft made, or have the stock one shortened. Most driveshaft shops can fabricate one if you tell them what you want, about $300. A cheaper solution for us budget ZCAR people is to have the stock one shortened and rewelded, about $100. This gets tricky because driveshafts should be shortened only at the ends for balance reasons. And for some reason Nissan T5 driveshafts neck down to smaller diameters right at the flanges. This means that after cutting, the yoke and flange ends are too small to weld up to the center tube.
But I went down to the local racing machine shop that does my head work in Richmond, Va (Ballos Machine). The owner used to race and make his own driveshafts and said he would take a stab at it. Somehow he broke the law of physics and cut both ends, shortened it, and magically rewelded a perfect bead for $90. It may not be perfect for a 500hp nitrous Z, but on a 6-cyl 2,200 lb car it works great. Don't believe a shop when they say it can't be done.
New Powertrain Industries version on top, shortened stock one on bottom.
My measurements for both were 29 1/4" from tip of yoke to rear of flange.
In August 2007 I decided I wanted a new T5 driveshaft with replaceable u-joints. So I contacted Powertrain Industries who advertise themselves as Japanese driveshaft specialists. They were very helpful and using my simple length measurements fabricated an excellent driveshaft that fit perfectly into my T5/240Z. What a concept...actually having a driveshaft underneath my Z with replacement u-joints! TIP: if you have a standard round differential flange, have a driveshaft fabricated with T5 front yoke and stock round rear flange.
DIFFERENTIAL FLANGE
The differential flange used on all ZCARs from 1970 through '83 was a round 4-bolt design that took 8mm bolts.
The T5 one is on the left
The turbo T5 cars used a special square flange with 10mm bolts. The bolt-holes are also in a slightly larger parallelogram shape (not quite square) like the earlier flange.
The bolt holes might look spaced similarly, but they're not. You can't drill or modify the older flange though or you would damage it and throw off the balance. This flange used to be available from the Nissan dealer for $55. On the parts list of 1983 R200 differentials, it's the flange for the 5-speed turbo L28E. If you can't find the flange at the dealer, try to find a turbo differential in the junkyard. Even if you don't need the differential buy it just to get the front flange home. When you get there you will need to use an /impact wrench to break loose the 24mm nut on the front of the differential, then use a puller to draw out the flange. The new one then slips on by tightening the nut back on. Torque it to 130lbs.
REAR TRANS CROSSMEMBER
This is the rear crossmember that holds up the back of the transmission. The T5 uses the same rubber trans mount as the other Z transmissions, but the mount sits rearward about 2 inches, making the crossmember boltup tricky but not hard. You have to be a little ingenious and fabricate one yourself.
There are 2 rear trans-crossmembers on 1st generation Z's.
I went to the hardware store, and found a very thick (12 gauge) flat-steel angle-iron brackets (2"x6" long) with four holes. By bolting one on each side facing rearward into the existing body holes, the crossmember now bolts to them, rearward by 3 inches. Kind of scary how easy it was. However... if you have later 240-280Z with the heavier mount you will need to fabricate something a bit different.
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You also need to check the the exact position trans tailshaft and the driveshaft. Transmissions have to indexed inline with the differential flange, no angles in the driveshaft in any direction...you should have 2 degrees or less angle between the two. Use washers between the rear trans member and the bracket to raise and lower the rear of the trans to adjust this.
A trans shop could do this for you, but I used an old Hot Rod trick. I went and bought a piece of plumbing PVC pipe the same length and diameter as the driveshaft. I then held it in place on the rear of the trans, and "sighted" the alignment. My trans was 3 inches too low I found, and went from heavily vibrating to very smooth once I aligned it properly. So don't believe people who tell you indexing doesn't have an effect on driveshaft balance.
DRIVING IMPRESSIONS
The spread of the ratios feels great to me. Compared to a 1977-80 5-speed 1st is very low making 0-60 runs much quicker and there is a tighter spread between 2nd and 3rd. 5th gear is also very high, and 70mph with my 4.11 is only at 3500revs.
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