Hello all, I was looking around on ebay and came across a ZF 6spd that is being sold with trans, bellhousing, driveshaft, clutch, shifter, flywheel, the whole nine yards I think. I as just wondering if this is something that would be worth buying. I have been wanting to do a 6 spd swap. Ever since I took out my 5spd and replaced it with a TH350 I have wondered what I was thinking!! I know that those are rare and that is what makes me skeptical. I wonder about replacement parts and installation. Does anyone on these boards know much about the installation? How much different would it be from a T56 swap? BTW, this is out of a 90 Corvette it it matters... Any responses are welcome since I don't know much of anything about this particular trans and/or swap. Thanks in advance...

the odds that the belhousing will bolt to your block are very bad.....if it came from an ls1 style (gen III) small block it wont bolt up....and the clutch system is totally different

LS1's NEVER came with a ZF6

again, passing along mis-information isnt cool

the did in corvettes smart guy,

and the setup is totally different with a rear mounted transmission and a torque tube.....

they also come in pickup trucks equiped with manual transmissions as we speak, including the 6.0L vortec which is an identical block casting to the ls1, it is also a gen III small block.

the only difference is the bore and stroke combination, and the intake and cam in the 6.0L, the bellhousing from the truck will bolt directly to the gen III block, whether it be a 6.0L vortec motor or an ls1/ls6

so get your info straight before you open your mouth genius

All right, don't make me separate you two... be nice!!!

Anyway I appreciate your info. I don't know if it makes much difference but this trans came out of a 90 corvette. I assume that means it was an LT5 powered car. I have very little working knowledge of an LT5 so I don't know how the bolt pattern is for the bellhousing. I also don't know about the clutch system for a ZF. My 92 Z originally came with the puny T5. NOw it has a TH350. I saved all the clutch hardware and pedal because when the money allows I would like to go with a 6spd. In case you are wondering I had the TH350, so it cost me very little to install it...

When I came across the ZF with just about everything needed to install it, maybe, I thought it was worth looking into.

If anyone else knows any specifics about installing a ZF into a 3rd Gen, please speak up. Thanks again...

Wrong. They came in Vettes in the late 80s and very early 90s. By the time of the LS1, GM had long since learned their lesson and adopted a far superior 6-speed trans, the T-56. Wrong. 90 Vettes had TPI (L98). The LT5 came out several years later later, 94 or 95 IIRC, for just a couple of years. Wrong.

Why do we have so much stuff in this post that's just blatantly WRONG? Thank you very much.

dude your an ***, go to the gm truck website and look at the transmission options.

i almost bought one with a 6.0L and a zf 6 speed.....its right on the window sticker of about half the trucks on the lot smart guy.

you really should educate yourself about these things before you open your mouth.

corvettes (c5's) are currently equipped with zf transmissions.....however it is a far different and application specific gear box that is part of the rear axle assembly.

go check out any new gmc or chevy truck with a 6 speed transmission, its a zf

its common knowledge...maybe you should pay more attention to whats going on.

this is what aggravates me about this site, everyone knows everything about everything

get a clue heres a link to the GMC truck website listing the options including the available transmissions......one of which is a zf 6 speed...... http://www.gmc.com/gmcjsp/sierra/spe...e=sierra2500hd

read that and tell me im wrong again.... your an idiot

Few years ago there a guy on this board that swapped in a ZF from a vette....I think his name on here was ZEBRA....costly swap compared to the T-56. Might wanna try searching his name.

I tried really hard to not get involved, but damnit, we have ALREADY had this discussion before, doesn't anybody pay attention????

ZF is the manufacturer of the transmission. So that means that ANY 6-speed transmission they make, can be called a "ZF-6 speed" Thats like saying that a 4 cylinder S-10 has the same transmission as a 2500 Sierra because they both have "Hydramatic 4-speeds", never mind the fact that one is a 4L60-E and the other is a 4L80-E. If you want to get technical, the Trucks had a ZF S6-650 while the corvettes had the ZF S6-40. THEY ARE TWO COMPLETLY DIFFERENT TRANSMISSIONS!

So, to repeat what you said yourself:

"you really should educate yourself about these things before you open your mouth."

And while your at it, please show me where you install the PTO on the Corvette "ZF 6-speed" and where do you put the CAGS solenoid on the Trucks "ZF 6-speed", please tell, I'm dying to know, since they are the same tranny...

92, to answer your question, it should bolt up fine, especially since it was the Corvette's 6-speed tranny GM borrowed when they built the Firehawk.

thank you RB and GMtech



what do i know anyways?

only went to the GM ASEP training center for 2 years, graduated and got my degree

i have straight info, so may i open my mouth now? :sillylol:

1989-1991 vette L98 with either 700R4 or ZF6
1990-1995 vette ZR-1 LT5 with ZF6
1992-1995 vette LT1 with 700R4 (4L60E begining in 94) or ZF6
1996 vette LT4 with ZF6 ONLY
1996 vette LT1 4L60E ONLY


NEW CORVETTE 1997-present
LS1 4L60E or T56
Z06 LS6 T56 ONLY


so get your info straight before you open your mouth genius
i'm sorry, but i find this part the the most ironic

SLP had a special bellhousing made to mate the ZF tranny to a Gen 1 sbc. These were used on the Firehawks.
Isn't the ZF-6 tranny in the vette stronger and better than the T56? Did they change for cost reasons? Cuz I know the ZF is expensive. I was told by a ZF dealer to just go with a T56 for my LT1 since the conversion kit they had was about $6K.

Zepher, thanks, now that I didn't know. Definatly useful information.

They also used an expensive dual mass flywheel that can be converted to a 'regular' flywheel, but the tranny makes alot of noise in neutral w/ the clutch out.

Check this site out, alot of good info!!!

Now all the work i did on my car, and me forgetting to reset my rev limiter 10,000 miles on the motor and 7,000 RPM.... Not a pretty picture (Thin cylinder wall +.060)

View Destruction

like i said, there is a zf 6 speed trans available for trucks, and it bolts up to a Gen III block,

explain to me how thats wrong.

i also pointed out the difference between the corvette transmission and the one in the truck, so once again, how am i wrong?

and finally, like someone already said i doubt a the zf 6 speed used in a firehawk will bolt up to a stock belhousing.

which one of the 25 (or so) existing firehawks of that generation did you take apart and check out the belhousing anyways?

im glad your a gm tech, but so is my brother and hes an idiot.......so that means absolutely nothing to me.

Thanks to all of you. I found out what I wanted to know. Now please would someone lock this thead so there can be no more mud slinging!!!!!!!:sillylol:

I've examined mine at great length and have lots of pics. My Firehawk seems to be the quietest of all of them from what I can tell speaking with other owners and driving in other ones. I love the tranny, perfect shifting that gives great feedback and feels fantastic when shifting, mechanical precision at it's best IMO...

I was thinking about the bellhousing the other day and I remember something about the SLP housing allowing a different style clutch and slave cylinder setup, more like a standard T5 style. There was one for sale in the classifieds a year or so ago. Does that sound about right?

IIRC, SLP sold a ZF6 conversion kit for thirdgens, so they might have done a modified belhousing, to use a t5 style clutch, with the ZF tranny :shrugs:

I have a ZF 6 speed from an 89 Corvette that I am going to put into my 89' Camaro. I chekced with SLP and they no longer have the kit with the specal bell housing. Although the T-5 slave cylender will fit earlier bellhousings the cylender it's self hits the trans tunnel as it is located at 9 oclock and needs to be about 6-7 oclock to clear the smaller trans tunnel. Then the ZF sits up higher and it wider so it hits the sides of the trans tunnel. I am hoping to get around a few of these issues as the LT1 I am swapping in sits a bit lower in the car. Then there is still the driveshaft issue and rear mounting brace to deal with but I know those can also be overcome.

Well, I think I am going to let the ZF idea go. Its not that I can't do the work neccessary to install it, I just don't want to. I would rather save for a Tremec or something that is less time consuming to install. I only have one car right now. If I buy my dads car next year when he gets a new one, maybe I will look into the ZF again. In the mean time the TH 350 works just fine...

Thanks again for all the info.

It's a whole lot easier, and probably a great deal cheaper, to put in a T-56. The ones from LT1 cars are a more or less bolt-in.

I am considering that. What does it cost roughly for a T56 and all the necessary installation stuff? What kind of power are they capable of handling? If an LT1 T56 is up to the abuse that an LS1 trans is capable of coping with, then it should work great for me!! Either way, it is going to have to wait until I can save some money...

It's about a $2000 swap if you get a good clutch and new hydros and a short-throw shifter. A lot of guys say the LT1 T-56 is a better tranny then the LS1 version. I don't know why, but I've heard it a few times before...it may have something to do with the slave cylinder, which tends to leak, and requires you to pull the tranny to fix it. The designs are nearly identical (with differences in the input shaft and front cover plate) and have the same power handling abilities. I'm not sure, but I think the factory rating is like 475hp and 450lbft. It's underrated.

FWIW I wouldn't trade mine for any other tranny out there.

*YOU'RE
*He's

And somebody please lock this thread. I can't understand the grammar from half of you people. If I tried to actually read it, my head would hurt. Again, I'm sorry.

LOL:sillylol: :sillylol: :sillylol:

I is a collage stoodent

I would have to disagree with this statement. From all the research that I have done I have come to the conclusion that the ZF that came in the early 90’s corvettes is stronger and better built then the T56 in the late 90’s Vetts and most certainly better then the T56 that came in Camaros. The germans build good stuff, except Volkswagens of coarse.

A transmission off a L98, LT1 or LT4 corvette will bolt up under a thirdgen. You have to modify the center consol because you may have some trouble getting it into first gear with the stock consol as seen here and here. You will also have to fabricate a custom cross member.

Here are some pics of the a thirdgen with a ZF (from TRAXION site)
- The cross member
- Another cross member pic

well considering ZF manufactures custom planetary axles for Bigfoot for use in their monster trucks, im sure the transmissions are top quality.....especially after seeing the truck sheetmetal axle housings they built for the foot guys

well i have a B.S.B.A, i'll make a not of it on the degree

89IrocZ

I agree that the ZF is a good piece, GM probably did it because the T56 is less bulky and is built here in the US.

also cheaper, cost wise that is.....

The ZF was also considered 'notchy' by many magazines standards, The ZF's I've driven definitely reflect that, they're notchier. The T-56 shifts a lot nicer, they are slightly weaker than the ZF. Because of the cost of the ZF many performance guys with corvettes convert to T-56s because they're cheaper to upgrade.