Hey everyone, so to start out I've got a 99 T/A with around 160k miles. My transmission is leaking fluid where it bolts up to the engine, so I believe my Front pump bushing is walking out. It's working right now, other than noisy shifts from N into P and R, and 1-2 shift makes the car lurch forward a little, but it's driveable.

My plan was to buy a junkyard 4l60, buy the kit online, and rebuild myself. I've never done a tranny rebuild, the most I've done was install my headers. I'm buying a different 4l60 because my T/A is my daily, so I'd like the current trans to last as long as possible to give me time to work on this trans without rushing and f**king something up.

I'm wanting to build the trans right the first time, and for it to withstand ~600-700 rwhp. The kits I've researched are good up to ~550, so I was wanting something stronger than that. Can I add some additional parts to one of these kits, or does somebody sell a kit for a 4l60 to hold that many horses?

I know that this isn't something for the faint of heart, but I believe if I have the time and stay organized, it's something I could do. My only issue is I'm a student so I'll be rebuilding the trans in my room instead of a garage. Will I need any BIG tool purchases for the rebuild? I have jackstands, no lift so I was going to pay for someone to do the swap itself.

Thanks in advance.

 

If you're wanting more than 550rwhp I would strongly suggest consider buying a 4L80E from the junkyard and building that. Why? Simple.

For starters, as far as I'm concerned getting a 4L60E to hold ~700rwhp is a gamble. It's VERY cost prohibitive as well to purchase the parts needed to get it close to those levels.

A 4L80E is:

- Cheaper. 4L80Es cores are often substantially cheaper than 4L60E cores, ESPECIALLY LS1 F-body cores.
- Stronger. A stock 4L80E is better than many built 4L60Es.
- Easier to build, especially for someone of your experience level. 4L60Es have a more complex pump and valve body setup compared to a 4L80E.
- Rebuild kits are much cheaper
- You have a better platform to work with
- Advantageous gearing, especially in a setup like what I'm guessing yours is. Not unheard of at all for cars to do a 4L60E to 4L80E swap and improve their ETs in spite of the extra weight.


With a 4L60E you're going to need to replace a LOT of hard parts. Just an example:

Sonnax SmartShell: $90
New A/C Delco Reverse Input Drum: $70
Sonnax Billet 2nd and 4th servos: $205
A/C Delco 5 pinion planets: $300

I could continue the list further just on hard parts, not including the actual rebuild kit with clutches, steels, seals, filters, gaskets, a $30 band, a $50 input sprag and so much more. Don't even ask me the price on the Sonnax SmartTech input drum, I'll let you Google that one and let you deal with that sticker shock

By that point you are ***** deep with no billet parts and a lot more to add to the list and it's still a toss up.

With a 4L80E, you don't need to change ANY hard parts unless you are using nitrous, make 4 digit horsepower or several other limited scenarios. A full rebuild kit, hydraulic modifications and you have yourself a transmission capable of more than what you are wanting for less.

Yes, you need to spend $150-$180 for a new crossmember, you need a new converter , and a few other odds and ends but you come out far ahead.

Just my opinion


Anymore info on the 4L60E to 4L80E swap can be found in this guide I wrote with us 4th gen F-body owners in mind: http://northtexasconverter.com/?page_id=8242

 

I don't think I could've asked for a better response. I was considering doing the swap but I figured the parts to swap would've been too expensive but I see now that building a 4l60 is more expensive.

Thanks for the detail and I've bookmarked your writeup. I'm trying to do as much I can by myself considering I haven't graduated yet so my income is hourly haha. I really appreciate it though, and I'm actually very excited to start building.

 

No problem man, I can understand that thought process completely. I also totally understand, I too have not graduated yet, two more long years

You will also save in tools needed to build the 80E vs the 60E as well. The low piston compressor tool for 4L60Es is anywhere from $60-$70 alone as well.

Glad I could help!

 

NorthTexasConverter has given you great advice, especially the reasons for going with a 4L80E. The basic idea is that a 4L80E with just a few upgraded parts and following the instructions for a stock rebuild will easily handle your power level.
In contrast a 4L60E for that power level will needs lots of special parts and you have to deviate from the stock rebuild instructions at every step.

However, in case you or the reader does want to rebuild a 4L60E, see my post #2 for instructions and tools in this thread:
https://ls1tech.com/forums/automatic...questions.html

Even if you have all the tools to rebuild an engine, you will likely need to spend $400 for special trans tools or have a very friendly/cooperative local trans shop do some of the steps for you.

 

NorthTexasConverter in the write up on the 4L60E to 4L80E swap in the link you posted, it mentions that you machine the output shaft so that a shock length F Body drive shaft can be used. Would you mine sharing how much you machine off the shaft?
Thanks

 

I actually should modify that. I don't use those kind of output shafts anymore, I only use the fully splined output shafts in our 2wd builds. They can be a pain to get ahold of but they're ideal for what I build the transmissions for.

As for machining the shaft, I don't have a preset amount I do everytime like with the forward hubs (another thing I'm looking to get away from), but I can get a picture of a machined shaft to give you an idea if that will help

 

Pics are always good. Thanks for the info.

 

Fully splined (what we use now)



vs cut (hopefully this gives you an idea)

 

Thanks for taking the time to post the pics.