LQ9 4x4 1988 RCLB questions

[Jake88]

New to this site and I'm planning on doing a 2002 LQ9 in my 1988 k1500. I have the motor and the harness and a place available to build a stand alone for a good price. I need help with transmission options and if they will bolt up to my LQ9. I have the 700r4 in it now with the old TBI 350. What will work best for this set up and still being able to use my 4wd without too many crazy modifications

 

[Shaun Anderson]

Your best option for transmission is to acquire a very cheap used 4L60E and have it fully rebuilt with all the upgrades to make it a 4L70E. That will handle the power of a stock LQ9 and it will bolt up to your factory trans to t-case adapter just like stock. That will also allow you to let the ECM control the trans shift points and firmness which are all fully programmable by whomever is going to be your tuner.

I would ditch the 700R4, because it's mainline pressure and shift points/firmness are determined, in part, by the proper installation/adjustment of the "TV cable". It is problematic to get that tv cable to work correctly with the LS platform. It's better to use the native electronically controlled version of the 700R4 mentioned above. Gets rid of all kinds of headaches.

 

[Christian Steffen]

Why not get a 4l80e? Shouldn't be any worse than a 4l60e.

 

[Shaun Anderson]

Why not get a 4l80e? Shouldn't be any worse than a 4l60e.

4L80E is longer (wider too), so that means new drive-lines or existing ones reworked to fit. Also have to slide the trans/tcase xmember back and remount it. Also means purchasing a new trans to tcase adapter, which can be somewhat pricey and difficult to find. Also would have to swap the 27 spline input shaft of the t-case to 32 spline. 4L80E is an exceptionally tough trans. No doubt. I have one in my rock crawler CJ6 behind a LQ9.

 

[90halfton]

Motor swap and low modification/ cost/ and ease rarely go together if you want to do it how I would consider "right".

 

[Shaun Anderson]

Motor swap and low modification/ cost/ and ease rarely go together if you want to do it how I would consider "right".

While I agree with this generalized statement, especially if we are talking about someone who is inexperienced, but there are ways to minimize the bleeding that can occur when one embarks upon the LS swap path.

OP asked what transmission he should use to fit to his LQ9 that would work the best and essentially be easiest to install.

Installing a 4L80E would handle any abuse thrown at it, but it's overkill in this application. OP has a 1/2 ton truck with 1/2 ton axles. I just think it's unnecessary in this swap and it goes completely against what he was asking, which is what trans will bolt in and work correctly/reliably for his application. 4L60E built to 4L70E specs. Been done by so many people with great results.

 

[df2x4]

My stock V6 C1500 has killed two 4L60Es, one of which was built way beyond OEM specifications. I'm aware that this is not normal, but the fact remains, it happened. While I agree that the 4L60E would be the easiest bolt in option by far, I personally would not trust one behind a stock LQ9. I'm sure there are people out there doing it, but I would not volunteer for that potential headache. I'm 4L80E swapping my truck, and my K1500 Suburban if/when the 4L60E in it decides to go. More work and money for sure, but I feel it would be a much better option in the long run. Especially for a six liter LS engine.

Good luck whatever route you choose!

 

[90halfton]

While I agree with this generalized statement, especially if we are talking about someone who is inexperienced, but there are ways to minimize the bleeding that can occur when one embarks upon the LS swap path.

OP asked what transmission he should use to fit to his LQ9 that would work the best and essentially be easiest to install.

Installing a 4L80E would handle any abuse thrown at it, but it's overkill in this application. OP has a 1/2 ton truck with 1/2 ton axles. I just think it's unnecessary in this swap and it goes completely against what he was asking, which is what trans will bolt in and work correctly/reliably for his application. 4L60E built to 4L70E specs. Been done by so many people with great results.

In my opinion it depends on how this truck will be used. As a DD you're completely right. If it's going to be flogged around in the mud or write his name in rubber in the parking lot there's no such thing as overkill . In which case you're correct about the 10 bolts being the weak knees of the equation.