TXCatfish

I'm running a 4k circle d stall that's a little tight for my new setup. Is there a 5-5500k loose converter available for 4l60e trans? I'm hoping I can just swap converters and use the same trans.

Thanks!

Circle-D_Brian

We could do a 230mm based 4l60 converter for you. It's a rare request, but it works great for a max effort n/a type of build.

-Brian

TXCatfish

Thanks Brian. What do most people do, swap to a th350/400?

The issue I'm having is I swapped my factory 10 bolt w/ 3.23's to a 12 bolt w/ 4.88's and the 60ft stayed exactly the same (1.60). In the burnout I have to get on the brake and linelock or the car wants to roll. Also pre-stage and stage I have to keep it under 2400 or it wants to roll, before I could stall it to 2800 before it rolled.

Just fyi the car is 100% bracket raced. The goal is to get the 60ft down and get it to leave better off the line.

Thanks!

TXCatfish

Or can I have the same converter restalled? Not sure if that is possible.

Thanks!

Circle-D_Brian

We can do some calculations on converter efficiency if you give me a full run down of the setup. I need:
-Trap RPM
-Trap MPH
-Tire height
From here we can determine what your gear ratio change did to affect the converter, and possibly what we can do to make this better.

-Brian

TXCatfish

Thanks. Would it be easier if I called you?

Circle-D_Brian

You can certainly call, but maybe for educational purposes we could continue in this thread. If it helps just one more person, then it's worth it.

-Brian

TXCatfish

Sure no problem. I'll verify the trap rpm tonight.

With the new combination: 1/8th mile
Trap RPM 6500
Trap MPH 97
Tire Height 28"

Thanks

Circle-D_Brian

Right now I'm calculating 14% slip. There is just a lot of gear in this setup. I'm thinking we can go to our 230mm converter and retain your 4l60. This would let you keep lockup and give you a looser converter for better E.T.

Option 2 would be a helper shot of N20 to loosen things up back to where they need to be. Let me know what you think

TXCatfish

Thanks. Definitely not option 2. What trans are most people running with short gears, 3 speed turbos?

And what is the price on the 230mm? I didn't see it on the website.

Circle-D_Brian

You may also look into Sonnax's 2.84 ratio input carrier kit to eliminate the big 1-2 rpm drop. Cool deal for the 4l60. Don't forget about the 4l80 as an option here also. I prefer to keep lockup whenever possible if you do any street driving. Pricing on the 230mm will depend if we are going to use your current converter or start from scratch.

-Brian

TXCatfish

I will look up the Sonnax 2.84 tonight when I get home.

What is the "big 1-2 rpm drop"? Sorry i've only ran the car one weekend since the rearend change. And I would be using the same converter.

Circle-D_Brian

The 4l60 is known for a rather large gear change on the 1-2 shift. In some circumstances its enough to drop the car out of the power band losing E.T. Stock is 3.06 1st to 1.63 2nd. This would bring you to 2.84 1st to 1.55 2nd. I'll pm you pricing for the 230mm unit.

-Brian