sillyiroc

I just saw a ZF T56 on ebay and i was wondering what is the difference between it and a regular T56? can I put this tranny in my iroc?

RB83L69

There's no such thing. Sounds likt a typical e-bay trick to make it come up no matter what you try to search for.

It might be a ZF, or it might be a T-56; or it might not be either.

I think you can put it in your IROC. You just need to make sure the cargo area is mostly cleaned out, and the tonneau cover (if you have one) is open. I think the hatch will even close.

TKOPerformance

A T56 is pretty easy to swap into your car.

A ZF six-speed from a Crovette is very difficult, because a lot of custom built parts are required.

I would be dead certain which trans it is before bidding. You don't want to get stuck with something that you can't use.

ScreaminDeamin85Z

if its a ZF..have fun trying to find parts for it, and if you are lucky enough to find them you might as well bend over

Parrydise7

iTrader: (1)

Didn't some Firehawks come with a ZF trans?

RB83L69

yeah .... like 2 of them .... and it's hard to find parts from either of those just laying around waiting for some e-bay victim to come along and be rescued

sillyiroc

The guy is selling two of them he says one is out of an 95 and a 96 4th gen. Are these any good? are they worth about as much as a regular t56? How is it different? does it bolt into my iroc just like another t56 would?

TKOPerformance

If they are out of a '95 & a '96 then that is the trans to buy. The '93 box has a super steep 1st gear, and doesn't have as consistent gear spacing as the later boxes. '98-'02 boxes won't work on a traditional small block, they are LS1 only.

This is a Borg/Warner T56, and is exactly what you want for a 3rd gen swap. It will bolt right in. You can reuse your stock driveshaft and torque arm.

How much are they going for?

iroc22

All of the 1992 Firehawks came with ZF 6 speeds and Dana 44 rears. You might be thinking of the 2 concept B4C's built with ZF 6 speeds (that weren't released to public of course).

RB83L69

OK, sorry.... 3 of them.

Actually, I know, it was 26. Still a mighty small universe of potential donors.

The T-56 is a much better way to go. But it's not a "ZF T-56". Like I said, the guy was just making sure that whatever people searched for, they saw his ad.

sillyiroc

I asked the seller if they were definatly ZF t56 and he hasnt gotten back to me yet. one of them has alot of miles on it and the other has like 60k. They are both starting at $700 with no reserve no one has bid on either of them. It comes with the bellhousing, flyweel, clutch, pedals.

Zepher

iTrader: (1)

SLP had a special bellhousing made for the ZF-6 to go into the Firehawks. It may have been made so that you could use the 3rd gen style clutch and hydraulics.

I bet that ad is for a regular T56.

I emailed a company a year ago that sells the ZF tranny's about retrofitting a ZF-6 into my 86 and they recommended that I just go with a T56 since it wasn't very cost effective.

He probably used ZF6 in the description for Vette owners.

sillyiroc

If it was out of a 4thgen then why would there be a problem with swaping it in.

Zepher

iTrader: (1)

If it was out of a 4th gen F-body, it wouldn't be a ZF, it would be a T56.
If it was out of a 4th gen Vette, it would a ZF6.

sillyiroc

I just got an email from the seller and he said he thought that they were all zf t56. He did not know that there is a difference. So it turns out that its just a t56 wich is good. Thanks for all the help.

TKOPerformance

They guy doesn't seem to know what he's talking about. Borg/Warner, which was later bought out by Tremec makes the T56.

A German company makes the ZF-6 trans used in C4 Vettes. ZF stands for two German words that I won't even try to spell or pronounce. Typically ZF transmissions are found in BMWs and other high end cars, but a few American cars have used them like the Corvette and a handful of special edition Camaros and Firebirds.

The transmissions are built by two entirely different companies and share nothing in common.

A T56 that is in good working order with what sounds like a nearly complete swap kit for $700 is a screaming deal. I'd snap that up if I was you.

sillyiroc

He doesnt seem to know what he is talking about. I am bidding on it, since he is calling it a zf t56 no one else has bid on it so it could be good for me.

jmd

iTrader: (4)

1993 had two different M6 ratios.

The 2.97 first gear set of ratios are extremely consistent 1-4. Slightly moreso than the 94-up ratios.

The 3.xx first gear set of ratios is less desirable for strength reasons but it depends on what you're looking for.

TKOPerformance

The '93 transmission uses a 3.36 1st, 2.07 2nd, 1.43 3rd, 1.00 4th, 0.80 5th, and 0.62 sixth. Tremec rates it to 350 lbs/ft of torque. Tremec has since discontinued this transmission, and all replacement 4th gen transmissions have the '94 and up ratios.

The '94-'97 T56 has a 2.66 1st, 1.78 2nd, 1.30 3rd, 1.00 4th, 0.74 5th, and 0.50 sixth. Tremec rates it at 450 lbs/ft. of torque.

The GM Aftermarket T56 has the same ratios as the '93 transmission, but uses a 2.97 1st gear. Tremec factory rates this unit at 400 lbs/ft of torque.

I chose the '94-'97 T56 for my swap because of the lower 6th gear, which effectively cuts the rear gear ratio in half. I also liked the lower 1st gear ratio, because it allows me to run a motor with a stock powerband (done at 5,000 RPM) and not have 1st gear act like a granny gear in a truck. I run a 3.73:1 rear gear with this combination and love it. It only turns 1,950 RPM at 80MPH! It's also nice to know that I have a significant reserve torque capacity for future engine modifications.

jmd

iTrader: (4)

Those were not the only ratios in 1993. The 3.36 first version came with 2.73 rear gears. The 2.97 first version came with 3.23 rear gears.

Do the math and you'll find that the 2.97 first gear 1993 ratios have a very even % drop between 1st through 4th gears.



Going through a T56 parts book, checking gear teeth count and doing the math to get the ratios verifies that the above is not accurate. Look at 2nd and 3rd ratios again. There has been inaccurate ratio info published for the aftermarket T56, such as years ago on sallee chevys site.


Me too.


The LB9 & L98 make torque and don't need a close ratio (like the 94-up f-body T56) first through fourth. The Z06 ratios are my favourite.

TKOPerformance

All that info came directly from Tremec by way of several PDF files that I was emailed by one of their representatives.

I'm not sure about the 2.97 1st gear being offered in '93. I was only provided information about the 3.36 ratio for that year. The '93 car was a transition model though, so I don't doubt that things like this may have happened with that year. The problem is still how do you verify what gear the trans has if it's from a '93? That's why I would still avoid them.

You're right about the 2.97 providing better spacing, but since it wasn't available with a 0.50 6th I went with the 2.66 box to get the better 6th gear. The Z06 has even better spacing, but these were never offerd in a non-transaxel T56. I toyed with the idea of assembling a custom gearset using off the self parts, but it was cost prohibitive.

I agree about the abundance of torque with a TPI 350 too. I don't notice any real drop between 1st and 2nd gear, even though logically I know it's there.

jmd

iTrader: (4)

I know. I know. I will say that I've only had good luck w/ them in researching parts.


I fixed reverse in one.


The metal tag on the tailhousing bolt has a service PN.


I can build one w/ those ratios, I just don't have the $.

TKOPerformance

Do you happen to know what the service numbers are that denote the different transmissions for the '93 year? I just like knowing stuff like that. I've got a folder full of T56 info that I keep around for S&G purposes.

Yeah, I know you can build the T56 with the Z06 ratios if you've got the coin for all the gears. I wish I did, but just a basic rebuild cost me about $800 in parts (bearing kit, synchro kit, 5th gear, 5th/6th synchro assembly, and a few other ods and ends). It was basically a good trans, but I don't think the previous owner kept the clutch engaged long enough when shifting into 5th, because the engagement teeth on the gear were screwed up and the synchro hub and slider were worn. I tend to go overboard when I rebuild stuff too, but when I'm done it's like it left the factory, or better. Oh, I did the steel 3/4 fork too. Seemed worthwhile.

Parrydise7

iTrader: (1)

"yeah .... like 2 of them .... and it's hard to find parts from either of those just laying around waiting for some e-bay victim to come along and be rescued"

Actually, what I was thinking is that if the factory built them, the factory has to carry the parts for them (ten years, I think). I did some checking with a parts guy at a local dealership. Now, I only checked on that bell housing. I was told it was disco'd and there are none in dealer parts.

jmd

iTrader: (4)

SLP had a clearance on the remaining parts. They were selling the clutch pedals, bellhousings, I think the floor hump.

I think that ten year stuff is a fable; never seen confirmation of it; just rumour.

What about the ZF bellhousing isn't usable in the F-body? Obviously they were made to bolt up to the SBC and I believe the fork was canted (at least in 4+3 apps) so what else is the problem? Yeah, I should do a search.

RB83L69

4+3 isn't the ZF, it's a T-10 with a hydraulically-applied overdrive.

I don't know exactly what about ithe C4 ZF bell won't fit in the F-body. I just know it's been tried more than once (but not by me, so I don't have first-hand knowledge of it) and hasn't met with success thus far. If you find out, let us all know.

Parrydise7

iTrader: (1)

I've heard its ten years because that's how long the National Highway Traffic Safety Administration (NHTSA) requires the automakers to perform recalls on vehicles. So, the automakers stock parts for ten years. After that, if there is a problem with a vehicle, the automaker is off the hook and no recall is necessary.

However, I can't find that written any where.

TKOPerformance

They may be required to stock mechanical parts for 10 years, but plenty of interior and body stuff seems to be discontinued almost as soon as the cars hit the showroom floor.

This is one place where American cars lose out big. If I had a 30 year old Mercedes or BMW I could go right to the dealer and get whatever I needed for the car. Granted I'd pay a hefty premium for it, but the fact that these parts are still available speaks volumes about these companies. Basically they plan on their cars being around for a long time, whereas GM and other American car makers want them off the street as quickly as possible so that they can sell you a new car. It's almost like they are telling you "Hey, this car has a maximum lifespan of ten years, after that go back to your dealer and get a new one." It makes me mad, because we are basically left waiting until the aftermarket picks up the parts as the cars start to near classic status.

Oh well, enough of that rant. Think I got off topic a little bit.

jmd

iTrader: (4)

REALLY?

My point was that the fork is not straight out the side on C4 Vettes, nor 82-92 F-bodies, so that aspect of it may be close to right.

SLP isn't going to "hammer the floorboard a bit; call it done" a big $ Firehawk in 1992, so their reasoning for casting a new one may be different than Joe Average.

Maybe the reversed slave cylinder is what doesn't clear.

Should be fun to research, athough I'm on the "just do a T56" bandwagon too.

TKOPerformance

Yeah, from what I've heard the 4+3 isn't know for strength or reliability. The ZF is probably very strong, but the swap is complicated. The T56 is a much simpler alternative since it's a total bolt-in deal (with one or two aftermarket parts that are readily available).

BTW, the 4+3 was built by Richmond I beleive. This makes sense, since they own the rights to the T-10, and the 4+3 is just a T-10 with an overdrive unit as mentioned.

jmd

iTrader: (4)

Like you said, the 4 speed section of the 4+3 is a Super T-10 and is fine and strong and reliable. The only weak point is the OD unit.

The ZF is strong and well designed but is a three shift rail design and the rebuild is a lot more crap & expense than a T56.

sillyiroc

thanks for all the great info guys. It turn out its just a t56 wich is good.