I pulled my 4L60e out of my 97 Z28 (LT1) a few months back and had it rebuilt by a reputable performance builder here locally. He did mostly a Sonnex build with a few BG parts. Anyways, I ordered a Yank SS3600 directly from Yank (Matt is a great guy to deal with for the record) and received it a month or so later. I also ordered a TCI flexplate (399173) to replace the factory one. Then came time to install everything. Where I went wrong was not measuring everything first before installing it. After putting the transmission back into the car, the time came to measure the converter spacing with the 1/8” spacing rule in mind. Once installed, the converter was right up to the flexplate and barely touching it. It was not putting pressure on the flexplate, as I was able to spin the converter easily, but there was nowhere near an 1/8” gap either. I then pulled the transmission back out and started measuring to find my 1/8” difference.

I am 100% positive the converter is installed completely into the pump gear. This has also been verified by my transmission guy. Yank wants at least 1.125” from bell housing to converter pads when the converter is installed. When I measure mine, I have .935”. My transmission guy also measured a stock converter installed into a different 4L60 and said the measurement was a little less than 1”.

I’ve spoken with Matt at Yank several times and after measuring the converter several ways, we’ve verified it was built to their specs. I, unfortunately no longer have my stock converter to compare to. I’ve also measured the TCI flexplate to the stock flexplate and only found negligible differences... nowhere near 1/8”.

I stumped with where to go next. Has anyone experienced this or have any ideas what the issue may be? Thanks in advance!

 

Can you Post an image without the Torque-Converter... showing the Stator-Support and Input-Shaft.
Then an image of the Hub of the Torque-Converter.

 

This is a 30 spline shaft if that matters. I can get measurements also, if that helps. Thanks.

 

Forgive me... I know that you said that you were able to fully insert the Torque-Converter into the Transmission...

But I have had a stupid amount of people also say this to me... then I check the TC and find that it was not in completely.

What has your Transmission guy had to say after being able to be hands-on with your TC and Transmission?

 

He says it’s an issue with the converter. Yank says it’s a transmission issue. I’m at a loss. Here is a picture of it installed into the transmission. I don’t claim to be an expert by any means, but I don’t see how this could slide in any further. I’ve also verified that the converter is engaging the pump gear.

 

I would send them the photo that you just posted.
... as well as the Bell-housing to TC pad measurement.

 

That’s just it... I’ve sent them the photos and haven’t really gotten anywhere. That’s why I was hoping someone on here had experienced a similar issue.

 

flexplate on backwards? flexplate made wrong?

check the spacing of the flex plate compared to the stock one. I once had a flex plate that was stamped wrong and the flex plate sat too far away from the engine.

 

Did they have you measure the overall height of the converter? This is the height from the face of the hub(silver snout that goes in the trans) to the face of the pad where the bolts go into the converter.

 

Did you tell them that you have an "Early-Model" 4L60E with a 1-Piece Case?
...or did they ask you this?

The 4L60E Torque-converters for the Gen-3/ Gen-4 SBC (LS) Engines are Larger.
I have never tried to see if a Torque-Converter for a 300mm Input-Shaft will fit on the Stator-Support Shaft of a 298mm Transmission.

The 300mm version of the 4L60E has a longer Stator-Support, and a slightly larger Bell-Housing to accommodate a larger Torque-Converter.

 

KFxguy- I checked that already by measuring how far the new and original flexplate sat on the crank. They were virtually the same with like a .004” difference or something.


Slow_Five- Yank had me measure the overall height of the converter and that checked ok. It measures 5.950”, which is what they said it should be. Unfortunately, I don’t have the stock converter to measure or compare it to.


Vortec- The guys at Yank didn’t explicitly ask me about the bell housing, but they were aware it was a 4L60e LT1 combination. I hadn’t thought about the shaft sizes being different, that’s a good idea. However, even if was made for the longer LS shaft, that still wouldn’t give me my 1/8” discrepancy.

 

The stator tube is the same spline. the difference aside from the obvious spline difference and o-ring location is the spline depth and OAH.

The 300mm converter will slide on, but the hub will bottom out in the pump early or the nipple will bottom out in the converter(depending on cover design)

 

Craft: Can you drain the fluid from the converter enough to see all the splines in the converter and post a picture?
After seating the converter in the trans, it is difficult to pull back out of the trans at all?

Also if you haven't already try taking the o-ring off the input and sliding the converter in, does it go in further?

 

Once installed, the converter slides and about easily and never binds or hangs.

I have attached three photos below. The first is the best picture I could get looking down into the splines. The last three show my very rudimentary measurements of the over height of the hub and the space from the rubber o-ring to the back wall in the transmission ​​​​​​where the hub would bottom out against (marked with a black mark on the screw driver shaft). Now knowing these are the same measurement, that tells me the converter term is to big. Am I incorrect for thinking that or could there still be smoothing installed incorrectly in the transmission?

 

I'm curious what you ever figured out on this? Was planning on going with a Yank for my '96 Formula WS6 and while researching the idea I came across this thread! Any insight would be appreciated👍

 

Yank makes a good product. I own two of their converts and both have been flawless.

 

MMBM, the issue ended up being with the mounting pads on the converter. Since I didn’t have my original stock converter, I found one and compared it against the Yank converter. After measuring everything, I found the mounting pads were 1/8” thicker than the stock one. I took the Yank converter to a local machine shop and they milled each pad down the 1/8”. It then slid right on the input shaft and bolted up without issue.

Since it’s a weekend car, I only have about 400 miles on it so far, but I’m very pleased. Yank makes a great product and Matt provides the best customer service you’ll find. Even after this slight issue, I’d buy another tomorrow.

 

I appreciate the update! Thanks for responding👍