Blue/Black ZF6 labels - ZR-1 Net Registry Forums

Perry Mitchell · 09-18-2023

Can somebody explain the differences between blue and black ZF6 speed transmission labels? Which is better or more desirable? I have a 91 ZR1 transmission with black label that was removed from a totaled Z with 17,000 miles complete with bell housing, flywheel, and dual mass clutch sitting on my shelf. Not sure if I will use it in a future project or not. What is the value of this unit?

Corvettes White · 09-18-2023

Not sure of any differences. Blue were built in the US. Black in West Germany before the wall fell.

I would keep the black one just because it makes a story more nuanced.

George

secondchance · 09-18-2023

My understanding is the early Zs' black label ZF6s have higher torque rating but some of these transmissions (if not all) can be noisy at low speed. Later blue label ZF6s are quieter. I do not know when the change occurred (perhaps concurrent with 375hp to 405hp in 93?).
My 91 had a black label and 94 has a blue label.

Thomas ZR-1 · 09-19-2023

Picture from Bill`s homepage zfdoc.

Black label: 89-92 610 Nm max
Blue label: 93-95 540 Nm max

wfot · 09-19-2023

The black tags have the gear/dogs welded together, making them stronger. the blue tags have pressed on dogs, still very strong. also yes the tooth angel of the blue tags are different, making them a little quieter..

John

secondchance · 09-19-2023

Also, later blue tag throwout bearings have nylon sleeve whereas early black tag throwout bearings do not. This may be a contributing factor for later ZF6 being quieter.

tccrab · 09-20-2023

Don't forget that late model blue label have no reverse lockout ring on shifter, the have "crash through" reverse engagement.

Crabs

Perry Mitchell · 09-20-2023

Thank you all for the replies. So it seems there isn?t much difference in the two labels other than year specific. Possibly the black label is more desirable. Any ideas on the value of my transmission with shifter, bell housing, flywheel, and clutch assembly with only 17,000 miles of use?

Dynomite · 09-20-2023

1. Throwout Bearings.

I have a 91' ZF S6-40 Transmission (Black Label) Parts List No 1052-000-035 with a collar diameter of 1.373 inches and a 94'-95' ZF S6-40 Transmission (Blue Label) Parts List No 1052-000-087 with a collar diameter of 1.305 inches.

Post 38 - Throwout Bearings and Clutch Forks

Post 241 - Rebuilt Black Label Transmission Installed and New Driveshaft U-Joints

5ABI VT · 09-27-2023

Black = made in Germany
Blue = made in USA

early to 93 have a different input shaft diameter as well as the higher torque rating and associated differences. my 94 is an early car and has a black tag that has a later 'revised' 94-96 internals

09-18-2023	#1
Perry Mitchell Join Date: Nov 2018 Location: Washington Posts: 98	Blue/Black ZF6 labels Can somebody explain the differences between blue and black ZF6 speed transmission labels? Which is better or more desirable? I have a 91 ZR1 transmission with black label that was removed from a totaled Z with 17,000 miles complete with bell housing, flywheel, and dual mass clutch sitting on my shelf. Not sure if I will use it in a future project or not. What is the value of this unit?

09-18-2023	#2
Corvettes White Join Date: Dec 2003 Posts: 477	Re: Blue/Black ZF6 labels Not sure of any differences. Blue were built in the US. Black in West Germany before the wall fell. I would keep the black one just because it makes a story more nuanced. George

09-18-2023	#3
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,722	Re: Blue/Black ZF6 labels My understanding is the early Zs' black label ZF6s have higher torque rating but some of these transmissions (if not all) can be noisy at low speed. Later blue label ZF6s are quieter. I do not know when the change occurred (perhaps concurrent with 375hp to 405hp in 93?). My 91 had a black label and 94 has a blue label.

09-19-2023	#5
wfot Join Date: Jan 2009 Location: New jersey Posts: 156	Re: Blue/Black ZF6 labels The black tags have the gear/dogs welded together, making them stronger. the blue tags have pressed on dogs, still very strong. also yes the tooth angel of the blue tags are different, making them a little quieter.. John

09-19-2023	#6
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,722	Re: Blue/Black ZF6 labels Also, later blue tag throwout bearings have nylon sleeve whereas early black tag throwout bearings do not. This may be a contributing factor for later ZF6 being quieter.

09-20-2023	#7
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,654	Re: Blue/Black ZF6 labels Don't forget that late model blue label have no reverse lockout ring on shifter, the have "crash through" reverse engagement. Crabs __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]

09-20-2023	#8
Perry Mitchell Join Date: Nov 2018 Location: Washington Posts: 98	Re: Blue/Black ZF6 labels Thank you all for the replies. So it seems there isn?t much difference in the two labels other than year specific. Possibly the black label is more desirable. Any ideas on the value of my transmission with shifter, bell housing, flywheel, and clutch assembly with only 17,000 miles of use?

09-20-2023	#9
Dynomite Join Date: Aug 2009 Location: South Dakota/California Posts: 3,797	Re: Blue/Black ZF6 labels 1. Throwout Bearings. I have a 91' ZF S6-40 Transmission (Black Label) Parts List No 1052-000-035 with a collar diameter of 1.373 inches and a 94'-95' ZF S6-40 Transmission (Blue Label) Parts List No 1052-000-087 with a collar diameter of 1.305 inches. Post 38 - Throwout Bearings and Clutch Forks Post 241 - Rebuilt Black Label Transmission Installed and New Driveshaft U-Joints __________________ Left Clickable links -Solutions- LT5 Modifications/Rebuild Tricks Low Mileage ZR-1 Restoration 1990 Corvette (L98) Modifications LT5 Eliminated Systems LT5 Added Systems LT5/ZR-1 Fluids 1995 LT5 SPECIFIC TOP END REBUILD TRICKS Last edited by Dynomite; 09-20-2023 at 11:42 PM.

09-27-2023	#10
5ABI VT Join Date: Jun 2013 Location: Toronto Posts: 783	Re: Blue/Black ZF6 labels Black = made in Germany Blue = made in USA early to 93 have a different input shaft diameter as well as the higher torque rating and associated differences. my 94 is an early car and has a black tag that has a later 'revised' 94-96 internals