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4+3 vs. ZF 6 spd

A

auto_x_al

Guest
I have been throwing around the idea of swapping in a ZF6 in lieu of the Doug nash unit. Can this be done easily and is it more cost effective after initial investment? Additionally I have heard people using lighter "single mass" or one piece flywheels for racing application. This will be a racing application and gear chatter is not a big deal as long as it does not harm anything. Any input would be greatly appreciated. Thank you all in advance.

Al
 

Roadster Guy

Well-known member
Joined
Oct 17, 2004
Messages
261
Location
Rolling Hills NE of Toronto
Corvette
1996 Roadster CE/LT4/F45
losing 30 LBS from the engine's rotating asembly..pros & cons...

In the July 2006 Issue of Corvette Magazine on page 37 the "Tech Nerd" replies to a letter regarding removing a dual mass flywheel and installing a 12 pound aluminum unit in a 96 LT4. You should check it out. He points out some negatives, however the one place he thinks a lighter flywheel really does help is in roadracing since the engine spins up faster when it's unloaded.....so that seems to apply to you.

Regarding the tranny swap I don't really know. I have seen discussions on it, but can't recall where and what was concluded. Make sure you check the CAC knowledge base and do a search of previous threads. Someone here should be able to advise you........Welcome to the CAC:beer
RG
 
Joined
Jun 24, 2002
Messages
252
Location
Abingdon,MD
Corvette
1996 Torch Red LT4
I think it would be alot of work and expense to change to a ZF6sd. I believe Tremic or one of the big tranny makers has a direct bolt on replacement for the 4 + 3. Good luck, Guy
 
A

auto_x_al

Guest
I think it would be alot of work and expense to change to a ZF6sd. I believe Tremic or one of the big tranny makers has a direct bolt on replacement for the 4 + 3. Good luck, Guy

The issue lies with the NCCC rules. I have to run equipment that was available with an L-98 motor. I can update and backdate within the C4 generation as long as everything is compliant with an L-98. I have 2 4+3's so having the spare tranny is not an issue with the 4+3. I was just thinking if it was reasonable price wise and close to being a bolt in swap I would consider it. Thanks for all the input!
 
A

auto_x_al

Guest
Keisler makes a 5 speed that bolts in.

Keisler with the tremec was going to be the way to go but it was never offered from gm and that would put me in a class where I would not be competetive with under 600hp.
 

c4cruiser

Well-known member
Joined
Feb 22, 2002
Messages
971
Location
Lacey, WA USA
Corvette
87 Gold Z52 Coupe 02 EB Z51 Supercharged Coupe
The 89-91 cars used the ZF6 box and the L98 motor so I would think that parts from those years would fit in the earlier car even to the point of being a bolt in. You may have to use the later C-beam to get it to bolt up.

The later hydraulic clutch system may have be used and you can just remove the cooler lines and plug up the connections at the radiator. There may be some differences in the floor tunnel and console but a sawz-all may help with clearances.

Exhaust should not require any modifications around the ZF6.

There is a person over on the Corvette Forum that is trying to get a group purchase together from a vendor that has a half-dozen new trannies available. Price is somewhere around $1450 each. Don't know if they come with shifters or not. If the rules allow for a aftermarket shifter, then a Hurst or B&M unit will be worth the money.

You could find a decent used ZF6 on eBay if you didn't want to pay a higer price.
 

JoBu

Active member
Joined
Nov 3, 2006
Messages
26
Location
Space Coast, FL
Corvette
1985 Silver Coupe
Sorry I don't have a very detailed response for you, but I do recall seeing an article in a Vette mag in regards to this swap. Your tunnel will have to be hacked (modified). I also believe you need a different length driveshaft. Dang, I wish I could be of more help. Have you tried to do a search on Google or another search engine? I would think someone would have an article scanned out there somewhere. Ok...I found a little information. I hope this helps you out. http://www.digitalcorvettes.com/forums/showthread.php?t=21327&highlight=6-speed+swap I hope the link works.

Cheers,

Joe
 
A

auto_x_al

Guest
You guys have been very helpful. I was thinking the C beam and the driveshaft were going to change and i am sure the bell housing will too. As far as the floorpan we have a roller that we have been using for parts and it was a six speed car and the shifter mount looks a bit diffrent. I would probably use the b&m or the hurst unit as the rules allow for aftermarket shifters in my group. I appreciate the insight as this now gives me some sort of idea what this project may ultimately entail. Thanks again,
Al
 
Joined
Jun 20, 2002
Messages
2,509
Location
Tallahassee, FL
Corvette
none right now :(
You guys have been very helpful. I was thinking the C beam and the driveshaft were going to change and i am sure the bell housing will too. As far as the floorpan we have a roller that we have been using for parts and it was a six speed car and the shifter mount looks a bit diffrent. I would probably use the b&m or the hurst unit as the rules allow for aftermarket shifters in my group. I appreciate the insight as this now gives me some sort of idea what this project may ultimately entail. Thanks again,
Al

If you go for it, try to get one from 89-93. they hold up better. I think they are the black label units (as apposed to the blue label from 94-96 when they eliminated the reverse lock-out), but can't remember for sure off the top of my head.
 

G Winter

Well-known member
Joined
Aug 21, 2004
Messages
2,177
Location
NW Iowa
Corvette
1990 red convert 6 sp
Another thing to think about, what rearend do you have? If you don't have the dana 44 you may want switch that at the same time.

Glenn
:w
 

Hrtbeat1

Well-known member
Joined
Nov 24, 2002
Messages
923
Location
MS Gulf Coast
Corvette
'90 coupe (gone) '96 CE LT4 Z51
I think the blue labels are GM factory, from what I've read the black labels are ZF factory rebuilds. I've even seen double tags .... blue and black. The crash thru shifter came about later in the production run ... maybe '95. The LT5 ZF6 tranny is about 1/2" shorter, so it won't fit right for a L98 or LT1/4. The magnesium bellhousing is a hard to find, specialty item. The bolt pattern to the tranny itself is the reason.

There is a lot of information on the ZF tranny here. They may be able to answer your question.

:w
 
A

auto_x_al

Guest
Another thing to think about, what rearend do you have? If you don't have the dana 44 you may want switch that at the same time.

Glenn
:w

We are in the process of repairing and rebuilding our 44 right now.
 
L

Louis Bartay

Guest
I have been throwing around the idea of swapping in a ZF6 in lieu of the Doug nash unit. Can this be done easily and is it more cost effective after initial investment? Additionally I have heard people using lighter "single mass" or one piece flywheels for racing application. This will be a racing application and gear chatter is not a big deal as long as it does not harm anything. Any input would be greatly appreciated. Thank you all in advance.

Al


WWW.ZFDOC.COM go to this web site for Z51 Performance. Call Bill on their phone Monday and he will explain what it takes for the swap. The Black Label ZF was assembled in Germany and the Blue Label was assembled in the USA. I think there was a improvment in the strength in the Black Label(second gear) that Bill does when you send him a used ZF to be upgraded and rebuilt. Good Luck, hope this helps.
 

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