Ok, So Talk Me Out Of A ZF-6

[tonyleed]

Looking to start a thread on exactly what it will take to mate a ZF S6-650 to the 6.5; in my case this is a swap out for the 4L80E and rounding out the discussion to cover swapping out other transmissions is a good thing. Am seeing where there is some interest in the ZF-6, but the search feature is not working well with query items like “ZF-6”, “ZF S6-650”, etc so it is a little tough to get a feel (or results) where anybody has completely worked through a ZF-6 conversion.

Am nearly convinced that the 4L80E is not the right tranny for me given my preference on speed control is with the throttle / gearing and then friction when necessary. I do have an ECM tune which gets better TCC lock-up above 45 mph (versus the OEM tune) which I like, but brake application forces an unlock which I do not like. Resulting from a good bit of research and conversations on the topic of getting the 4L80E to act more stick-like, it looks like this is a square-peg and round-hole goal where the OBDII programmers have yet to conquer this yet and likely it is simply outside of what the 4L80E will do anyway. Another research area was addition of a BD Torqloc to get the lower gears to lock-up at lower speeds, and while this tool looks nice, it seems to have a mild temperamental aspect of throwing a code in OBDII systems or making the tranny go into limp mode if not handled correctly.


Enough of the background and on to the topic . . .

Am seriously thinking about the GM variant ZF S6-650 as it is pretty much what I want:
- A standard shift.
- Plenty beefy to tow and a proven platform.
- Lower engine RPM’s (and noise) on the highway.

For swapping to a ZF S6-650, here is what I have so far:
- The ZF S6-650 was converted into an Avalanche 5.3 gasser with a really good write-up, so I know this is close to a drop-in solution but it does need some fabrication / parts replacements.
- Bolts up to the 6.5 (and, from what I am seeing, most if not all of the GM V8 engines).
- Heavier than the 4LXX and NV platforms by about 60#’s.
- Costs more than the NV.
- Need to shorten the rear drive shaft and get a longer front shaft (latter not necessary for 2WD).
- Need to install all the clutch pedal guts and cut a hole for the stick.
- Might need a lift kit or modifications to the body (depending on the suspension).
- (Self evident, but listing anyway) An ECM tune when replacing an automatic.
- (Self evident, but listing anyway) A towing clutch (Luk, South Bend, etc).

Only pieces that I have not dug into yet are:
- Verifying that the misc transfer cases bolt-up to the ZF-6 (looks like they do) and (for the push-button 4x4 systems) whether a wire harness extension is necessary due the ZF-6 pushing the x-fer back a few inches; also need to verify whether the input shaft mates with the ZF-6 or need to change the shaft.
- Making it work with the push-button 4x4 system so that the system knows when the transmission is in neutral (confident this is workable otherwise the push button system would not work with a NV).
- Whether it needs a different flywheel (and if it does, definitely a single mass and NOT the dual mass).
- If a different flywheel is necessary, does it need a different starter?
- Whether my 8600# suspension will need a lift or hump expansion; or put another way, which bodies / suspensions need modification.
- Whether the speedometer needs recalibration and if so, is it changeable by software or ship it off for another ECM tune.

Here is what I am trying to avoid:
- Moving this thread out of the 6.5 section as the focus is how the ZF S6-650 mates to the 6.5 versus a general transmission discussion (not to mention am not seeing a ZF-6 Forum (yet)).
- Comparing the ZF S6-650 to other transmissions: focus is how to make the swap work and nail down / work through any ‘gotchas’ that I have not already caught.

Have you made any progress on this?

I have a 99 GMC suburban 2500
7.4/4l80e

Right behind it sits a parts truck 02 GMC 2500hd
8.1/zf6

In the bed is an lq9 6.0..

I'll be taking the 6.0,zf6, and tcase from the donor and putting into the suburban...

Any tips would be great!

 

[GM Guy]

Ok, since the thread was resurrected, figured I better chime in.

In 2016 I bought a 06 Duramax factory ZF6. While I enjoy it for the most part, and it has proven to be fairly robust, the parts availability has me spooked to ever swap one into something else. The cost and availability suck, and the size isn't favorable for swapping.

For what a used ZF6 can sell for, a guy can go buy a new Tremec tr4050.

I have heard good things about the 4050, seems to be similar in size to the NV 4500, but can handle more power.

Off-Road/Truck Transmissions | RSGear

www.rsgear.com

Is one seller, here's another https://shiftsst.com/nv4500?gclid=C...AlRH5o27qpF4b0Us9nYt_mX26ZxCISnRoCwdAQAvD_BwE

I think going forward when I can't find anymore good used nv4500s, I'll be going to the Tremec.

 

[WarWagon]

Have you made any progress on this?

I have a 99 GMC suburban 2500
7.4/4l80e

Right behind it sits a parts truck 02 GMC 2500hd
8.1/zf6

In the bed is an lq9 6.0..

I'll be taking the 6.0,zf6, and tcase from the donor and putting into the suburban...

Any tips would be great!

WHY???

Cost to do this isn't going to be worth the fuel saved over the 454.

A better engine "to get out of it's own way" than the "Dog" 454 mediocre GM pushed on their loyal customers ... You are choosing poorly. Use the 8.1L engine. If you are going through the trouble make it worth it! The 99 is one of the better 454's for this body style so again: why?

@GM Guy is spot on. You are building a vehicle with a transmission that is essentially not repairable. No parts and some of the experts for this era of MT's have retired and closed up shop.

Era specific example: Although I respect the NV-5600 mentioned on here it's slow shifting and parts are not the main concern. Standard Transmission and Gear of Tuscon where Richard Poels set a standard to lube the rear bearing that all new cases now have machined in has retired. (Fix the problem of rear bearing lack of lube failure.) You will be hard pressed to find anyone who knows them as well as he did.

Nothing worse, and expensive, than fighting a Dammed clutch problem and/or transmission problem where it has to come out more than once. The MT's were a low bidder exception where the OEM's hardly gave us anything worth a damn. Low demand and the OEM's finally got rid of the warranty problem despite the fuel savings... as auto's finally were able to get close enough esp. by locking in the TCC below 45 MPH this era didn't exactly do.

 

[MrMarty51]

Did I get tired, or, did I get lazy ?
Run manual transmissions for so many years that I got tired of shifting, nothing but automatics for Me.
Besides, if a situation arises that I would get stuck in a snowbank or mud bog, rocking a truck with an automatic wins over a manual transmission every time.
Okay, I’m done. Carry on.

 

[jrsavoie]

Did I get tired, or, did I get lazy ?
Run manual transmissions for so many years that I got tired of shifting, nothing but automatics for Me.
Besides, if a situation arises that I would get stuck in a snowbank or mud bog, rocking a truck with an automatic wins over a manual transmission every time.
Okay, I’m done. Carry on.

Same here.
I was good with the getrag 5 speed I had in the 1989. Very smooth shifting.
I always heard they wouldn't hold up. But that trans went at least 600,000 miles and was still going when the engine locked up.
I've never cared for the NV4500. Neither I've had were easy shifters.

The Spicer 6 speed in The 1991 International 4700 put the NV4500 to shame also. Very smooth shifting

 

[DieselAmateur]

Thank you for the info on the 4050 @GM Guy, I didn't know there was a still in production alternative to the NV4500. Pretty neat that they're cheaper than a cryo- treated NV4500 rebuild too

I was vaguely interested in a ZF6 only because I don't know of any adapter that will mate the NV5600 to the 6.5. The extra low gear is really attractive for heavy towing. My least favorite thing about the NV4500 is the large drop in gearing between 3rd and 4th

I did find though that the 4050 bolt pattern is only for the 96+ GM bellhousing, same as all Dodge NV4500. So if one wanted to drop a 4050 into a 92-95 GM they'd have to get the newer bellhousing, possibly an older style from Advance Adapters that can take the mechanical linkage, or maybe even drill out the old bellhousing to fit the new transmission. The 96+ uses the same upper two bolt mounting locations, but the lower holes are roughly 1.5 inches lower and 1/2 inches closer together.

 

[GM Guy]

Thank you for the info on the 4050 @GM Guy, I didn't know there was a still in production alternative to the NV4500. Pretty neat that they're cheaper than a cryo- treated NV4500 rebuild too

I was vaguely interested in a ZF6 only because I don't know of any adapter that will mate the NV5600 to the 6.5. The extra low gear is really attractive for heavy towing. My least favorite thing about the NV4500 is the large drop in gearing between 3rd and 4th

I did find though that the 4050 bolt pattern is only for the 96+ GM bellhousing, same as all Dodge NV4500. So if one wanted to drop a 4050 into a 92-95 GM they'd have to get the newer bellhousing, possibly an older style from Advance Adapters that can take the mechanical linkage, or maybe even drill out the old bellhousing to fit the new transmission. The 96+ uses the same upper two bolt mounting locations, but the lower holes are roughly 1.5 inches lower and 1/2 inches closer together.

Last I checked the 96-07 bellhousing was still available new.
The 92-95 definitely isnt, and was not the best design, kinda crack prone.
All a guy would have to do is buy a clutch kit and hydraulics for a 96+ application to run the 96+ bellhousing, definitely the best route to take.

 

[DieselAmateur]

Although the 92-95 bellhousing has more moving parts and thus more to go wrong, I prefer the external slave to the internal design of the 96+. Not having to pull the trans to replace the slave is a big plus for me.

 

[GM Guy]

Use quality slave components and you wont be dropping it, aka avoid chain auto parts store stuff.
I was using the aluminum slave from o-reillys thinking it was better than the plastic for my external slave 95, and after swapping it 3 times I gave up and swapped it out for a LUK plastic and havent touched it since.