Hemi Conversion Automatic Transmission with Low Line Pressure - JKowners.com : Jeep Wrangler JK Forum
 
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post #1 of 3 Old 05-15-2015, 06:40 AM Thread Starter
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Hemi Conversion Automatic Transmission with Low Line Pressure

My taller half had a transmission issue. It would hesitate and towards the end started to slip. Caveat: this is in a JKU 2007 Sahara with a 5.7 Hemi and a (2009) Dodge Ram 1500 automatic transmission. He can do most stuff on his vehicles himself, but the automatic he took to a shop. (He said if it had been a manual, he couldve done it.)

They diagnosed "low line pressure", told him he needed a complete transmission rebuild (everything like except the gears inside and the housing iirc) - and charged him a buttload of money. So they did the rebuild.

It went back to the shop 2 days later - the rebuilt transmission wasnt going into overdrive all the times it should have. Sometimes it would, then it wouldnt and he would be running 3200 rpm on the highway (37s with 4.88 gearing).

The second diagnosis: "low line pressure". Hmmmmm....vaguely exactly the same diagnosis that led to the rebuild. Under warranty, they put some part on it (dont remember what it was called) that would make it build more pressure. So of course he is kinda pissed now wondering was this part what he needed all along and never really needed a complete rebuild? Or whether the rebuild was faulty and this part is just a bandaid?

One of the thoughts (not sure if it was his or the transmission shop) is that the problem is weight. The truck it originally came out of wouldve weighed what 6500-7000ish pounds (just did a quick google search-I didnt weigh a truck lol). As much of a pig as the JKU is, I believe it is closer to the 4000-4500ish pound range. Is this even plausible that weight difference could have this effect? Doesnt seem right tho as for the first what 20k the transmission behaved just fine - that if this was an issue, it would have always been a issue. So another thought we had is maybe it has something to do with the computer, some code took a crap or something (especially because of the conversion all of the computer parts need to talk to each other ie the Hemi/transmission piece and the Jeep piece)?

The engine/transmission only have about 20k-ish on them in the JK if I recall correctly. They were installed used, but he doesnt have the details (he bought the JK used with the conversion already done).

Any ideas?

2014 JKR "Bob" - RK X Factor 2.5, Nitto Trail Grapplers 37x12.5x17, Auto, 5.13, Rock Hard Skids, PS HD Cross member, Artec Axle Armor F&R, Artec Rear LCA Mounts/Skids, Synergy Rear Axle Side Weld on TB Bracket, PSC Hydroassist
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post #2 of 3 Old 05-15-2015, 06:41 AM Thread Starter
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Oops meant to put this in Modified Tech if any admin is inclined to move it I am cool with that.

2014 JKR "Bob" - RK X Factor 2.5, Nitto Trail Grapplers 37x12.5x17, Auto, 5.13, Rock Hard Skids, PS HD Cross member, Artec Axle Armor F&R, Artec Rear LCA Mounts/Skids, Synergy Rear Axle Side Weld on TB Bracket, PSC Hydroassist
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post #3 of 3 Old 05-15-2015, 06:55 AM
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Quote:
Originally Posted by queenmallcrawler View Post

As much of a pig as the JKU is, I believe it is closer to the 4000-4500ish pound range.
a 4door on 37's and a hemi, you are probably looking at 5200 pounds plus, easy.

Don't know the answer to your question, although I would guess, the weight is making any difference.

TC
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