baddriver Posted August 28, 2003 Share Posted August 28, 2003 This has already been discussed quite a bit, but I am still on the fence about which tranny to use. My plan is to install an LT-1 350 from an F-body. The logical and recomended tranny is the t56 that came behind this engine. However, for half the price, I could get a t5, which weighs less, and will drive the speedo cable (an additional $200 savings because I don't have to buy a new electronic speedo) However, the t5 is rated to 300 lb-ft of torque, while the LT-1 is capable of delivering between 310-340 lb-ft depending on the year. (or is it ft-lbs....?) I might take the car to the drag strip once or twice to see what she'll do, but I mostly autocross and I won't be buying drag slicks. Could I get away with the T5, or will this be a mistake? Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted August 28, 2003 Share Posted August 28, 2003 As long as you don't get the "drag strip bug", and buy sticky tires, and dump the clutch a lot you should be alright with the t5. But if you get the "more hp bug" your better off with the T56. Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted August 28, 2003 Share Posted August 28, 2003 I have over 50k miles on a T5 behind a built 350 and it works fine. It has seen a hand full of drag strip runs plus hard street driving (no drag radials). Use a good, high performance oil (ATF) and you should be fine. Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted August 28, 2003 Share Posted August 28, 2003 Having installed both but very little road time on them I can give you some install insites. You will need to spend another $75 on the T5 for a speed sensor that also drives a cable, available from JTR. Except for the slave cylinder (if you are using the f-body bell with stock slave) there is no tunnel clearancing required for the T5. The T56 requires some fin trimming and tunnel clearancing. Stock f-body slave on the T5 requires trimming of the accelerator peddle. Early T56's with the external slave should NOT be modified per JTR, IMHO. The plastic T5 slave has more material at the hydraulic connection and can be drilled out safely. The T56 slave has a narrowed down section at the line connection and will leave that area extremely thin when drilled and tapped for a 1/8"NPT connection. I contracted with a machinist to make me an adapter from the GM proprietary roll-pin style fitting to 1/8"NPT and used two hoses. adaper cost me $30 plus shipping. The T56 shifter fits much better in the Datsun shifter hole than the f-body T5, better centered. Quote Link to comment Share on other sites More sharing options...
Phantom Posted August 28, 2003 Share Posted August 28, 2003 I have the T56 behind an LS1 in a 280Z. The tunnel only needed some very minor pounding in two areas and no fins trimmed on the T56. That being said, if I weren't going to abuse the car, I'd be better off with a WC T5. The T56 gears and the available differential ratios just don't work as well together as I would like. To have a useful 6th I need a rear end ratio that burns the tires in 1st & 2nd. If I adjust for a better ratio on the low end it is hard to find a place where the speed limit is high enough to run above 'lug speed' in 6th. That being said - I'm still glad I've got the T56 because I am going to abuse the car on the strip and I don't want a tranny that will shell on me when I get the stickier tires and pour it to them. Quote Link to comment Share on other sites More sharing options...
80LS1T Posted August 28, 2003 Share Posted August 28, 2003 In my 280ZX LT1/T56(93') I can cruise at 90MPH @ about 2200RPMS! I have a 3.55 rear end. So basically 6th gear is almost useless...unless you are doing a HIGH SPEED RUN! However like the other guys are saying...the T56 will take more abuse no doubt about it. I think its rated at like 450Ft-Lbs! Guy Quote Link to comment Share on other sites More sharing options...
Guest BigWhyteDude Posted August 28, 2003 Share Posted August 28, 2003 so where would a T-5 trans shifter and T-56 shifter be oriented in the shifter hole of say a 280z ? towards the front of the hole back middle??? Quote Link to comment Share on other sites More sharing options...
baddriver Posted August 28, 2003 Author Share Posted August 28, 2003 Hey, everybody, thanks for the input. Hearing from a lot of people who are using the T5 is encouraging. I probably should have mentioned that I'm working on a 260Z. I searched the archives a while, but I knew you guy's all wanted to brag about your transmissions, so I posted my Q. The additional $75 for the speed sender is much easier to swallow than the $450 mod to drive a speedo cable with the t56, and I like my speedo with the high-beam indicator and brake-warning light that I only just got working. With the Transmission question out of the way, I only have to find a good design for an AC mount. I almost went with a TPI just so I wouldn't have to spend $$$ on new AC brackets, but I am convinced that I will find an inexpensive way to keep my AC, even if I have to weld the compressor to the block. Has anyone had a close look at the brackets for the LT-1 caprice with the towing package? I saw a picture and it looked like the AC compressor was mounted high like the S&P brackets. Are these available anywhere? Thanks again, Jeff E. Quote Link to comment Share on other sites More sharing options...
Phantom Posted August 28, 2003 Share Posted August 28, 2003 Shifter location depends where motor is mounted. My motor is about 4.5" forward of firewall and the shifter is about 1/2" forward of where the stock shift came through on my 280Z. Quote Link to comment Share on other sites More sharing options...
dot Posted August 28, 2003 Share Posted August 28, 2003 In my opinion the T56 has to be the finest transmission ever designed for a mass production vehicle. The shifts are effortless. I have had mine apart for a bell housing alignment and the insides are the finest of the machinists art. I have had a T5 apart out of necessity and there is no comparison. With a 411 gear I cruise the 4 lane at 2000. A 390 would probably been more sensible but wasn’t on sale at the time. Take the time to save the cash, you won’t regret it. I used the VDO speedo. It is easy to set up and looks close to the original. Cheers...:::Glenn Quote Link to comment Share on other sites More sharing options...
jbeech Posted August 28, 2003 Share Posted August 28, 2003 So how happy are you with that Jag V12? How much more than a SBC does it weigh? Quote Link to comment Share on other sites More sharing options...
Guest benjlv Posted August 29, 2003 Share Posted August 29, 2003 In my opinion the T56 has to be the finest transmission ever designed for a mass production vehicle. think BMW trans...my old mans M3 is one of the few that i would say that it "snicks" into gear. you can have a T5 built to handle a lot of abuse for about a grand. I have a friend running stickies and 11s with a built T5 in a mustang... A built up brand new T5 will cost you less with core than a T56 will.... Quote Link to comment Share on other sites More sharing options...
Guest tom sixbey Posted August 29, 2003 Share Posted August 29, 2003 one of my mustang buddies holds our local transmission record of 3 T5's in two weeks. yep - he wrote off 3 T5's in two weeks, but that was with 400 horses and sticky tire drag launches the entire time at the track. I would not worry about it unless you absolutely abuse your car. Quote Link to comment Share on other sites More sharing options...
Guest benjlv Posted August 29, 2003 Share Posted August 29, 2003 dont know. His is just with mild performance heads and cam and a 100 or 150 shot of N20 he hasnt got very many miles on it yet Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted August 29, 2003 Share Posted August 29, 2003 so where would a T-5 trans shifter and T-56 shifter be oriented in the shifter hole of say a 280z ? towards the front of the hole back middle??? Don't have that answer (maybe someone does) , but here is a handy link that shows dimensions of T5 and T56 so you can comapre. http://www.thirdgenresource.com/transmissions_information/ Quote Link to comment Share on other sites More sharing options...
Heavy Z Posted August 29, 2003 Share Posted August 29, 2003 I have a non-wc T5 in my 240Z. I drive it hard daily. I used to be freaked out because I'm way over the torque limit of the tranny, but this thing just keeps on trucking. How long is my question, but it feels/sounds no different than a year ago. As said, a T56 is stronger, and has the 6th gear to keep the gas mileage cool in hyper drive. But for half the cost (if you aren't a clutch-dumping fool) a T5 will do the job. If mine grenades next week I'll come back and edit this post, but for now I'm standing behind the T5. Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted August 29, 2003 Share Posted August 29, 2003 so where would a T-5 trans shifter and T-56 shifter be oriented in the shifter hole of say a 280z ? towards the front of the hole back middle??? I used the JTR kit both times. On the T56 with the motor pushed forward in the slotted motor mount towers the shifter came up right smack dab in the middle of the hole. With the T5 the motor was set about an inch farther back and the shifter again comes up about the middle but offset to the left side. I had to trim about a half inch off the edge of the hole for it to clear. This is using the f-body bellhousing which rotates the tranny about 15 degrees. If you use a straight up bellhousing I bet the shifter will fit better. Either way once you get the console and trim pieces back on you never notice. Quote Link to comment Share on other sites More sharing options...
Z-Dreamer Posted August 30, 2003 Share Posted August 30, 2003 While a T-56 is certainly strong enough for most street applications, it comes with a weight penalty, it's about 50 lbs. more than a T-5! If you want the best of both worlds go to: http://www.g-forcetransmissions.com for the ultimate T-5! 600HP+ in a 3,300 lb car with drag radials producing low 10 second 1/4 miles. Mark Quote Link to comment Share on other sites More sharing options...
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