MrVette90l98mt

My LS3 appears to be killing my ZF6. I pretty much finished the LS3 swap and have about 800 miles on the LS3 with 113,500 on the ZF6. Saturday I went for a short 30 mile drive with the roof off and notice when I got back home while driving at low speeds I can hear what sounds like a supercharger type of whine in 1st, 2nd & 3rd under acceleration. In 4th and the upper gears the sound is very faint or goes away completely. Car shifts smoothly with the occasional hard shift.

Facts:

-Bought the car in 2009 @ 97K mi Probably never changed the oil
-I Changed trans oil with Amsoil 5-30 (same part number as recommended on ZFdocs website) when bought and before each track day (4 HPDE's with L98)
-Whine can be heard in Neutral and will go away with clutch depressed.
-Probing around with stethoscope proves the sound is coming from the rear of transmission, I assume rear counter shaft bearing has gone bad or the counter gear shaft has shifted.
-I changed oil prior to 30 mile drive due to oil lost during R&D of new VSS for LS3 my thread:
https://www.corvetteforum.com/forums...put-issue.html


Can the counter gear shaft shift causing noise?
Where to have the ZF6 rebuilt?
Other places besides Standard transmission and gear or Rockland standard gear?
Rebuilt ZF6 on the shelf anywhere?

I got a quote for 4 grand for a rebuild, just checking to see if there are other options I may have missed or not discovered yet.

T-56 options? seems like it's going to cost roughly the same as a rebuilt ZF6 but may have a higher torque capacity.

QCVette

I am not sure where your noise is coming from or even if your noise is the normal ZF sounds.

You might check with ZF doc. He can help you diagnose the noise and also can do repairs, etc.

http://www.zfdoc.com/

He has helped quite a few on the C4 forum. He helped me with information when I was swapping mine, and also I got some parts from him. He is a pretty good guy to work with.

RWDsmoke

My ZF6 was really noisy shortly after a clutch change. It Sounded like a bearing to me. ZFdoc convinced me it was an alignment issue. I pulled the trans again and had the bell housing surfaces checked for flat and parallel. After a little touch up to the surfaces the noise was gone. Seems to be a common problem with these transmissions, but an easy fix.

phDiesel

Another confirmation of Bills knowledge on these things. He's currently solving my problems and has in the past.

Tom400CFI

That seems unlikely, to me. There have been many, way WAY more powerful engines in front of a ZF6 w/o issues.



Sounds pretty normal to me. Here is mine, bone stock. They all sound about like that.....


When I FIRST pull out of my pit-spot, you can hear what I consider to be normal 1st gear whine in a ZF6. Also at 0:30 when I downshift to first and mat it...FYI, this is an earlier/"Black tag" ZF6 which would be the noisiest variety.



If there IS a problem, the countershaft bearing COULD cause noise.

I would rebuild it myself, if it were mine (and did have a problem)

I'd get parts from RS Gear.

I would never trade a ZF6 for a T56. NO WAY. I've had 4 T56's...**** boxes. The ZF is way, WAY better. I REBUILT THE BLOWN T56 in my wifes, "Wife Driven" CTS-V. They're better than their predecessor (the T5)...but that's not saying much.


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MrVette90l98mt

[/QUOTE]When I FIRST pull out of my pit-spot, you can hear what I consider to be normal 1st gear whine in a ZF6. Also at 0:30 when I downshift to first and mat it...FYI, this is an earlier/"Black tag" ZF6 which would be the noisiest variety.[/QUOTE]


That is very similar in the sound that I am hearing, but mine will have the same frequency and amplitude across 1,2,3 at all loads. The thing that scares me is this is a sudden change 30 miles ago from what was "normal" in the past 7 years with a SPEC single mass flywheel. I know microphones are more sensitive to picking up transmission noise than what we will hear. I will try and get a video up with a mic recording this weekend.

During the build I bought lakewood adjustable dowel pins to dial in the bell housing. If I remember correctly I dialed in to within .004" it never crossed my mind to check flatness after doing all the mods to keep the pull type clutch.

Does anybody know for sure if ZFDoc is still in business? During the LS3 swap I inquired about a ZF rebuild a year ago with no response. I emailed him today, and still no response. Anybody know him personally?...tell him to check his emails?

VikingTrad3r

thats a heck of a plug for zf. i had no idea they were that good.

dorri732

His website has a phone number listed: Phone (602) 319-6575.

Maybe try calling him?

Tom400CFI

Check out "TPI421"s posts...look at what he is doing with a ZF6. They are good.

Tom400CFI

I think it's good that you're checking things.

I'd point out that if you had a counter shaft bearing that was failing, I'd think that you'd also have whining in 5th and 6th gear too.

whalepirot

Just sent a txt to him. I've experienced periods where I waited for a reply from Bill.

He replied via txt.

v8vette84

This is his own personal opinion. I personally have had 2 T-56's myself in addition to 2 buddies who currently run T-56's and not one of them has ever had an issue.

I don't discount the strength of the ZF6 but I still don't believe the T-56 is even in the same ballpark as the T5 like Tom400CFI is implying or that the T-56 is garbage compared to the ZF6. After all which transmission did the general continue using on their flagship car? The T-56...

If the T-56 was so crappy why would it have been used in all the manual C5 and C6 Vettes in addition to the Z06 until 08' plus Terminator Cobras or the Dodge Viper?

The T-56 is a great transmission just like the ZF6. I personally wouldn't hesitate to get/rebuild either one. I just got a better deal on the T-56 at the time.

856SPEED

When I FIRST pull out of my pit-spot, you can hear what I consider to be normal 1st gear whine in a ZF6. Also at 0:30 when I downshift to first and mat it...FYI, this is an earlier/"Black tag" ZF6 which would be the noisiest variety.[/QUOTE]


That is very similar in the sound that I am hearing, but mine will have the same frequency and amplitude across 1,2,3 at all loads. The thing that scares me is this is a sudden change 30 miles ago from what was "normal" in the past 7 years with a SPEC single mass flywheel. I know microphones are more sensitive to picking up transmission noise than what we will hear. I will try and get a video up with a mic recording this weekend.

During the build I bought lakewood adjustable dowel pins to dial in the bell housing. If I remember correctly I dialed in to within .004" it never crossed my mind to check flatness after doing all the mods to keep the pull type clutch.

Does anybody know for sure if ZFDoc is still in business? During the LS3 swap I inquired about a ZF rebuild a year ago with no response. I emailed him today, and still no response. Anybody know him personally?...tell him to check his emails?[/QUOTE]


If you are running the SPEC single mass FW (especially an aluminum) one that is exactly why you have a noise at neutral w/o the clutch engaged and it goes away when you press the clutch pedal. There is no dampening there like they had with the EOM very heavy, DMF. They are no longer made (the EOM dual mass). That is completely normal and you can run the snot of out and probably will never hurt it with that LS3. That LS3 is not coming near the potential to hurt these things.

I have a SPEC alum. FW behind an Gen1 SBC that puts down nearly 370 rwhp and that ZF (blue tag) has 0 issues with it after many years.

We have seen guys running 10's on stock ZF gearboxes.

Tom400CFI

I think you put some words in my mouth there.
*the T-56 is garbage
*same ballpark as the T5
*T-56 was so crappy
Please quote where I said any of that so that I can correct it.

I guess I DID use the term "sh!tboxes"...and it IS my opinion, but it's not unfounded, that's for sure. Trans's that shift into "NO MAN'S LAND", BLOW UP, while "woman driving" at a constant speed on the highway, reject shifts at the drag track...yeah, when you compare that to the performance of the ZF6...it's not good.

Additionally, no stock T56 is going to take the kind of "hits" that TPI421 is feeding into his ZF. They won't do it.

The T56 isn't terrible though, I didn't mean to imply that it's in the same league as a T5 b/c it's not. I said it was the replacement for and an improvement over the T5, which it was, but a T5 improvement isn't saying much b/c the T5 sets a low bar (for tq capacity at least -the T5 does shift more reliably than the T56 in my 3 T5/4 T56 experience).

My comments were more so in the context of ZF6 vs. T56; there is no comparison, and the T56 can't take what the ZF can.

Why did GM move to the T56? That isn't "proof" of anything; they did so b/c it met their criteria, and it was/is a cheaper solution. Same reason Ford moved to the MT82, 6 speed in the Mustang. How'd that work out? Point being, an OE making a change is not "proof" that the change was for the better.


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SurfnSun

Cost and complexity/ease of repair.

v8vette84

Apparently "the t-56 is garbage" and *T-56 is so crappy* have COMPLETELY different meanings than they are "**** boxes"....

I'll bet your response claims I wasn't able to quote you EXACTLY...

The meaning of this sentence can be confused and I apparently deciphered it wrong compared to what you wanted it to say. Despite that it sure doesn't say the T-56 is light years ahead of the T5 either...

You sure love to bring up TPI421's car and ONLY his car... There are FAR LESS ZF6 trannys out there compared to the T-56. Why wouldn't there be more T-56 failures? Also ONE car/tranny is not really solid proof that EVERY ZF6 is, in your words "way, WAY better" than every T-56.

I agree with that but it still proves the tranny was reliable and stout enough to take the abuse GM knew it would receive from owners otherwise GM would have replaced it MUCH earlier. (Especially behind the LS7) I have hardly heard about any T-56 failures, same as the ZF6.

Can you prove that with actual data to back you up? Otherwise you are claiming your opinion is a fact and it makes you look like this gentleman right here>>>

Tom400CFI

Damn right I do. B/c I know that NO stock T56 could take that hit. And his has, for 20 years!

Want more? Look up "rklessdriver". There are plenty of other big hp/ZF cars out there...you can do some of your own research.



Well, I just told you about a T56 failure; mine. Z06 has tq mgmt. Put a early Z06 trans behind a 400+ engine w/a 200 shot and slicks...see what happens. GM did replace the T56 as soon as they could. TR6060 in '08.



Just my own.

Of course, none of this addresses the shifting deficiency. "No man's land".

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cv67

Have a T56 with all the good hardened parts inside and wouldnt trust it to hold up to anywhere near the abuse that the ZF can take.
If anything the input shaft would shear off

T56 is certainly not bad but its nothing compared to the ZF in terms of sheer strength imo.

Jim is running crazy amounts of power through his with hard launches lots of nitrous and has never been apart...bone stock. Show me one factory trans that could take 900 lbs tq over and over.

MrVette90l98mt

Here is a video of the sound I'm hearing. 10 min long first portion is car on the ground cell phone under the car at idle, cycling clutch, and reving. Second portion is driving around town to a privet road for WOT testing.

Test setup:

Samsung S5, under car video.
Cheap Chinese Go-Pro knock off, eBay special
In car Audio recorded with a Tascam DR-05
Video editor: VSDC free video editing software, edited by me
Mic: Yamaha mic that came with my 7.1 home theater receiver mounted to the windshield pointing at the shifter.

Car build:

LS3 EROD create engine
SPEC billet Steel LSx to ZF flywheel
SPEC stage 2 Pull type clutch
Driver side poly engine mount
Pass side OEM rubber engine mount.
Trans oil changed 30 miles ago and noticed whine present (N,1,2,3) Amsoil 5-30
This is a sudden change from What I considered as normal ZF6 noise with these parts

I don't have A/C Yet so some of the in car audio is with windows down.

~6 minute mark is WOT and heavy throttle at low speeds. You can also hear my Hurst shifter rattle/buzzing...which is annoying and also figuring that one out as well.

My thoughts:
I wonder if my frequent Trans oil changes flushed all the synchro wear particles out and is no longer providing a cushion for the gears and bearings? Oil thinner than than the old oil mix allowing more NVH?

Your thoughts?

1985 Corvette

Did you check the bellhousing alignment during the swap? That LS motor doesn't have the power to bust a properly set up ZF drivetrain. I know you ended up using a quick time bellhousing with some modifications. Gearboxes can whine if not perfectly spot on lined up after the bellhousing is fastened to the block, and possibly a host of other issues. I sent a paypal to ZF Doc recently for some quick parts after he sent me an invoice, so he is still doing business.