4+3 to 6 speed conversion
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 844
Likes: 0
From: Cape Cod Ma
4+3 to 6 speed conversion
I have an 85' vette with the 4+3 trany. Im building an engine for the car that will have around 450-500 h.p. and I was thinking about puting a richmond 6 speed in the car to handle the extra power.
I know thare are other alternitives out there but not too sure what to do. Can I do this swap for under 3k
If anyone knows of a place that sells a conversion kit or a trany for this car, 6 speed would be great or a 5 speed please post.
I know thare are other alternitives out there but not too sure what to do. Can I do this swap for under 3k
If anyone knows of a place that sells a conversion kit or a trany for this car, 6 speed would be great or a 5 speed please post.
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Originally Posted by redfast
how strong are the zf six's
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
Team Owner
Joined: May 2001
Posts: 36,175
Likes: 2,511
From: ...tearing up the highways, one state at a time™®©
Keisler www.keislerauto.com may have a solution for a 6 speed conversion
they advertise C4, five & six speed kits...
they advertise C4, five & six speed kits...
