I have the opprotunity to acquire a ZF tranny and an LT1 engine from a 93 vette. I hear rumors that the ZF transmission is fairly indestructible. Is this true?

Its for my C3, as I dont really have a problem, modifying things.

 

Nothing's indestructible, but it's a robust tranny for sure... Try www.zfdoc.com form some comprehensive ZF6 info.

 

From ZFDOC

Larry,

ZF Industries put a very conservative capacity rating on both the 610Nm and 540Nm rated S6-40s.

The 540Nm (400 lbs ft) version will easily handle up to 600 lbs ft of torque if built correctly.

The 610Nm (450 lbs ft) version will easily handle up to 800 lbs ft of torque if built correctly.

The only setup that may break the 540Nm transmission is putting a 150 straight shot No2 system on a 450 rwhp naturally aspirated motor where the No2 is not progressively (computer transitioned) introduced but just slams the extra 150 hp into the system.

The weak point is how the 540Nm unit’s synchronizer clutch body is affixed to the 2nd speed gear.

It is spline-fit and crush-crimped into position where as the older 610Nm unit’s 2nd gear synchronizer clutch body is welded into place. All of the 610Nm synchronizer clutch bodies are welded into place.

The 1st, 2nd, 5th and 6th speed gears on the 540Nm type S6-40 are spline-fit/crush-crimped but only 2nd gear sees the torque leverage anywhere near that required to distort/unseat the crimp. When this happens, the clutch body ring ruptures into 5 or so pieces, most of which get punched through a 4 inch hole out the side of the case turning into a $3000 repair job.

As you can imagine, this is a very ugly type of failure.



If you don’t plan on adding a crude 150 straight shot No2 system to your motor then the 540Nm rated ZF S6-40 unit will work very well for all of your engine power to driveline management needs.


See Ya,

Bill Boudreau

ZR51 Performance

Cave Creek, AZ

(602) 319-6575
--------------------------------------------------------------------------------

From: Larry Dickey [mailto:larry@dickey.com]
Sent: Wednesday, June 16, 2004 7:16 AM
To: billb@zfdoc.com
Subject: RE: 4+3


Hey Bill:

If I got to the ZF, can it handle 405RWTQ and what else is needed to do the swap, can I use my flywheel etc?
Larry Dickey
--------------------------------------------------------------------------------

From: Bill Boudreau [mailto:billb@zfdoc.com]
Sent: Monday, June 14, 2004 9:17 PM
To: 'Larry Dickey'
Subject: RE: 4+3

Hi Larry,

Sorry it took so long to reply, been very busy lately which is a good thing.

GM is clearing out the last of their ZF S6-40 transmissions from inventory.

If you are at all serious about converting over to the ZF S6-40, I strongly recommend that you contact your local GM Parts

Department and purchase one of these transmissions a.s.a.p. P/N 12455189 (ZF S6-40 540Nm).

It has been 4 weeks since the GM’s clearance price sale began and from what I’ve heard, there are currently less than 70 of 400 units left in stock.

GM is selling these units to the dealer for an incredibly low price of $1800 new complete with shifter. That is $2800 less than what they normally sell for.

Converting your 4+3 to a ZF S6-40 is the best way to go.

Regards,

Bill Boudreau

ZR51 Performance

Cave Creek, AZ

(602) 319-6575

 

I am looking to run around a 650-700hp Twin turbo road race application. Not really looking to drag much but I might a little bit.

I just want to make sure that things arent gonna blow up on me.

 

The ZF6 is a great transmission.

My only concern is fitment into a C3.

I know that Keisler has the TKO with kits that will fit perfectly. And some of those are good to 600 ftlbs.

1993 was the transition year for the ZF6. If it has a black tag, it's the stronger unit, if it has the green tag, that is the less strong unit. In 1993, it could go either way.

 

It will be a bitch to install (having installed several smaller T56's in C3's) because of its size but it is rather indestructable. I consider myself to inflicted more abuse to a ZF than just about anyone ever has and I never critically damaged one. The only incident I ever had was a third gear syncro that disentegrated when I blew a shift while on the button. That was a simple fix (relatively). To put it in perspective I ran a 571 hp 396 sbc and a 250 pill behind a McLeod Street Twin; I left on a 5500 rpm sidestep and ran a best ET of 9.91 at 141... Yeah, the ZF is a mac-daddy of a stick...
-Jeb

 

I really dont want to pay 4 grand for a tranny. Rsgear sells raceprepped T56s for 2800.

In this particular case I can get an LT1 and ZF from a 93 vette for about a grand. sell off the LT1 and get half my money back.



Is that little black thing there the tag?

 

yes. That's the black tag.

You are right... you can recoup by selling the LT1.

Infact, if you sell on eBay, you might just more then recoup. You have the ECU and the engine harness, plus, sell the DM Flywheel with it, because it will be needed to keep the engine in balance. You might hit nearly a grand for all that.

These are some of the fitment issues you might run into:

1) The shifter location

2) mating the c-beam boltup with the chassis. This will require a custom made bracket to bolt the tranny up to the chassis.

also, change the oil and use BMW dealer-sourced Castrol TWS 10-60 synthetic motor oil.

since you are road racing, I highly suggest the Hurst shifter.

 

The shifter location I can deal with, if its similiar to the T56 I can deal.

I am gonna need a new crossmember anyway

Interesting.

Do you think the tranny will be good for 650hp?

 

http://www.hotrod.com/techarticles/43599/index2.html

 

excellent thank you

 

From that pic, it looks like a '92. My '93 has the black valve covers.

 

Either way.

 

I talked to the member that is installing a ZF in his C3.

The shifter location in the console needs to be changed but thats a black peice of plastic.

And the transmission tunnel needs to be modded with a hammer.(I like this mod, I am good at hitting things with a hammer) Also I need to convert from a mechanical clutch to a hydraulic clutch(the part I dont know how to do)

And make a new transmission crossmember and an adapter brackets.

This seems doable.

 

So how does a Hydraulic clutch work?

I understand there is a slave cylinder, and that probably means there is a master cylinder somewhere. So it works something like brakes. push the little pison in a good way and the big piston moves a little bit.

Any pics or a diagram on how this clutch all works.

 

Indestructable if you only look at the the power numbers its rated for, not if you count all the people who have problems with synchros.

Synchros on that thing will wear out fairly easily, but thats really all you need to worry about. ZFDoc builds them to withstand 1000hp, or so they say.

 

The ZF is rated signifigantly better than the T56.

 

The black tag is killer. The synchro problems come from bad clutch hydraulics.

I have faith in Bill@ZFDoc. He is the one person who really knows his stuff. When the time comes to rebuild my black tag, he will get it. And the $2800 required to make it perfect.

 

That pretty much decribes it. You have to install a master, fits on the fire wall, and a hose, the rest is part of the bell housing. It's real easy, and never requires adjusting.

For your application, check with Doug Rippie, they have modified the slave to react faster.

 

I know, and in terms of quality it is. I just think you need to expect having synchro problems at some point in time.