Adding Park to a 3L80 trans

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Adding Park to a 3L80 trans

Post by Kurt Lesser » Wed Sep 09, 2015 8:08 am

Let's try this again. Please PM me if it still won't allow you to access the file. I changed the permissions so that anyone should be able to view it.

This is an article I wrote for MVPA's Army Motors magazine back in 2001 about adding a Park position to the HMMWV.

Here's a link to the Google Docs page:

https://drive.google.com/file/d/0B6mfKm ... sp=sharing
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Re: NEW Adding Park to a 3L80 trans

Post by Action » Tue Sep 22, 2015 10:07 pm

The link works.

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Re: NEW Adding Park to a 3L80 trans

Post by Clarke » Wed Oct 14, 2015 4:44 pm

Many people would say that the drive-shaft e-brake on the older trucks is inadequate - certainly I've found it so offroad. The A2 e-brakes in the calipers are infamous for sticking and dragging the rotors. Park gives you an option for when you aren't on an incline to not use the e-brake if you don't want it.

As far as why not just upgrade to the 4L80E - because that's a $3000 upgrade in parts alone. $800-900 for the A2 body harness (assuming you already have a 12/24V alternator and don't need to buy one of those too), $1200-1400 for a reman trans and a couple hundred for the TCM, and 500-800 for the shifter assembly.

$850 (shifter and internal parts) or $2200?

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Re: NEW Adding Park to a 3L80 trans

Post by claptonisgod » Wed Feb 17, 2016 7:28 pm

How readily available are the internals for the trans and 24v/LED bulbs for the shifter? I see the tutorial was written some years ago, and quick Googling didn't turn any of the parts up.
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Re: NEW Adding Park to a 3L80 trans

Post by Kurt Lesser » Thu Feb 18, 2016 10:21 am

To answer your question Fenris, the E brake does not work fine other than on flat, level surfaces. That's why the military chocks their wheels. Even on my slightly sloping driveway the E brake would not hold the truck in place unless I tightened it so much it would overheat and warp the rotor. Don't ask me how I found this out. They left the Park position in the same trans in the CUCVs, so why they removed it from the HMMWV is a question some no longer employed designer might be able to answer.

Admittedly I live in San Jose and there are plenty of shops that rebuild transmissions and was able to buy all of the parts necessary to do the upgrade for around $15 and have never gone out and asked what all new parts would cost but if you look at the parts you need to collect they're all small stuff. There are no hydraulic valve bodies or solenoids, just a pin, a pawl, a shaft, and a selector detent. Even if you went to Chevrolet and bought them I wouldn't think you'd be into them for over $100. As with most transmission jobs the money is in the labor rather than the parts. If you have a "Pick-n-Pull" type wrecking yard around you might find a core transmission that you could strip the parts out of. If you need some help just shoot me a PM with what you need.

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Re: NEW Adding Park to a 3L80 trans

Post by GPW43 » Fri Jun 03, 2016 8:59 am

Gents
Attached is the picture of the failure mode Kurt was presenting. I experienced it first hand and didn't even noticed it. I parked the HMMWV after a 20 min drive. Came to move afterward and it locked up. I thought it was the X-fer case at first, I spent few minutes troubleshooting it and couple of back and forth later ... BANG, the issue went away. Then I would hear this rattling noise and I thought I let go something in the rear Diff. My good friend Cam jumped on the back seat and we drove for 1/2 mile; got out and looked underneath. We got the picture, literally and physically.

For those who I am sure will comment - The brake was neither ON nor I noticed any loss of power but there was enough friction left on those pads to cause the disk brake to melt and warp to the point it locked up the shaft after I parked the car. This is from the tendency of increasing the tension on the E-brake to get it to hold the truck on an incline. In San Francisco area that is a NECESSARY undertaking.
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Attachments
HMMWV brake failure.jpg
Brake Failure Mode
HMMWV brake failure.jpg (62.48 KiB) Viewed 1844 times
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