3.73s in a QTl

I got a few questions and I believe you gentlemen are intelligent enough to have my answers. We got a small population compared to other Jeep forums but we lack the dumbasses so it works for the best. First, I know you can grab a front axel off a 4.7 or 5.7 but do the axels have a difference between the QTl, QTll, and QDll or is it all t-case? My second question is if I were to try this would the hypertech be enough to reprogram or would I need to go to the stealer?

Edit: On another forum I belive I have read of this being done to a WK I'm not sure who's or if they go into this issue I can't find it right now.

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QTI and QTII have the same axles, but QTII has the same tcase as QDII.

There are a few people who have swapped 3.73s into their QTIs.... I'm pretty sure Adam (07JeepXK) put a set in his friends WK.

I was the one that did the 3.73 swap on my buddy's 05 3.7 liter Grand Cherokee WK. You need to get a front differential out of a 4.7 liter with 3.73's and QT II. You will still use your stock cv axles. As for the rear we used Motive gear 3.73's for a chrysler 8.25 axle. The dealer can't do the reprogramming, but the Hypertech speedometer calibrator will be able to reprogram for the gear change. It's an easy sway if your familiar with setting up gears on a 8.25 rear axle. You will still use your original transfer case. No issues with his Jeep since the install.

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Originally Posted by 07JeepXK

I was the one that did the 3.73 swap on my buddy's 05 3.7 liter Grand Cherokee WK. You need to get a front differential out of a 4.7 liter with 3.73's and QT II. You will still use your stock cv axles. As for the rear we used Motive gear 3.73's for a chrysler 8.25 axle. The dealer can't do the reprogramming, but the Hypertech speedometer calibrator will be able to reprogram for the gear change. It's an easy sway if your familiar with setting up gears on a 8.25 rear axle. You will still use your original transfer case. No issues with his Jeep since the install.

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I have an 08 the ecu won't have any conflicts or anything. I believe there were small changes to the 08 from the previous models but I'm not sure what they are. I don't think the base models changed that much.

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As long as you use the hypertech speedometer calibrator for the gear ratio change you will be fine. You can even upgrade it to the Max Energy Power programmer and tune your Jeep

I think the OP may be right.... isn't there a model year that the programmers don't support for 3.7s? Though I thought it was an issue with 2005 WKs.... but you used it for that already.

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Originally Posted by Matt

I think the OP may be right.... isn't there a model year that the programmers don't support for 3.7s? Though I thought it was an issue with 2005 WKs.... but you used it for that already.

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That programmer worked fine for Jay's 05 WK. Hypertech lists the same programmer for 2008 so I dont see why it wouldnt work.

There was a year they made some changes to the ECM and it resulted in errors when people tried programming their vehicles. IIRC it only affected 1 model year and superchips/hypertech (I forgot which one) said they didn't have plans to update it to work. Ill have to do some searching later during lunch to see if I can dig that stuff up.

Called my buddy Tim... it was an issue with 2006 model years and the Hypertech speedometer calibrator. So he should be good with his 2008.

Easy way to find out. Before ordering the gears and front differential, get the Hypertech programmer. Try to program the vehicle and if it works, purchase the gears and front diff. If not send it back, get your money back and live with the fact that your stuck with 3.07 gears..lol

Can you post the part # of the Hypertech calibrator you or your buddy used? I already have the gears I just need the calibrator. Thanks.

Hypertech Speedometer Calibrator Part # 752501

Thank you sir!

Anytime. Let me know when you want to install them. Road trip!

how much money are we talking , not labor, just parts, and is there a noticible difference with the WK ?

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Originally Posted by NeilSmith

how much money are we talking , not labor, just parts, and is there a noticible difference with the WK ?

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For me so far:

Front Diff with 3.73 gears installed (used) and Rear 3.73 ring and pinion (new) - $400
Hypertech Speedo Cali - $200


And I still have a LOT more to go because I want to upgrade some things as well

Damn you got your parts cheap. It cost my buddy $1000 all together for parts. Front diff, rear gears and speedo calibrator. Install was free!

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Originally Posted by NeilSmith

how much money are we talking , not labor, just parts, and is there a noticible difference with the WK ?

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Definitely a noticeable difference. Jay's WK is running a 4 inch BDS with 33x12.5R18 and it was night and day.