3.6L Pentastar Transmission Options
I had a hard time finding info about what actually bolts to a 3.6L so I figured I'd consolidate all I've found out so far.
First off the Bellhousing bolt pattern is not even close to a 3GHemi/Small Block, not by a long shot. This Autocad drawing I made shows differences. The 3.6L in GREEN and the LA SB bolt pattern in White
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The 3.6 Pentastar Bellhousing most closely resembles the 2000 and newer Aluminum Block 3.5 and 4.0L SOHC[see below]. I haven't 100% confirmed it, but the resemblance is there as seen by the unique pair of bolt holes near the top of the bell.
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AUTOMATICS
The most obvious choice for a RWD swap would be to use a NAG1 from a +2012 Wrangler. The NAG1 swap has been done more than a few times when mated to a Hemi so it has more R&D to support it as opposed to the newer 8 & 9 Speeds.
Wranglers are most all 4WD so you don't need the whole transmission JUST the bellhousing. I've come to find out that a popular swap for your brand new +$37K Jeep is to spend another $15K-$20K to install a Hemi & pitch the 3.6L [Jeep guys are crazy]. They do this by simply SWAPPING THE BELL HOUSING from a LX Hemi NAG1 onto the Wrangler's 4WD NAG1. So 3.6L NAG1 Bellhousings are actually readily available as "new" take-off. Take-offs like this one shown below go for about $75 to $125 all day.
Again, the 3.5L Trans from 06-10 LX MIGHT bolt the 3.6L but might not. They used a "weaker" 42RLE 4 speed anyway so the 5 speed NAG1 would be a better choice imo. Just take a Hemi NAG1 and bolt on the Wrangler 3.6L Bellhousing.
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MANUAL Trans
Big issue here is there's only 1 OE option but its not a good one. The ONLY manual trans to bolt behind a 3.6L was a NSG370 6-Speed but ONLY 4WD as far as I've found. Novak has decent info on it.
CONS: 3.6 versions Harder to find[$$], Poor Gearing, Big Boned, Shifter position less than ideal, Goofy Driveshaft, Integral Bellhousing that is part of the Case.
PROS: Bolt on
Here's the NSG370 Gear Ratios 1st-6th
4.46 2.61 1.72 1.25 1.00 0.79
Not the best spread especially that 1st gear,,good for Rock Crawling but maybe not much else.
Jeeps used the NSG370 since 05 and if/when there was a rare occasion for a RWD, they just used the same darn 4WD trans but instead of bolting on a transfer case, they used this Goofy CV type driveshaft. Slick idea and I love the CV and damper but that doesnt make it easy to find or cheap. That shaft is ~$500 new and then you probably still have to cut it.
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Tremec TKO and T5
A TKO500/600 seems like a decent route. Everything from the Trans back has been already figured out so it's a welcome relief from the R&D and fabrication associated with this swap.
QuickTime now makes a Bellhousing to mount a TKO500/600 + Hydraulic TB behind a 3.6L. Thank Shannon at Redline Gauge Works for that[he's doing the same swap]. Part number is RM-4070 msrp $1132
Here it is on a trial fit
Pros: Easy TKO bolt-on
Cons: Cost, Weight, ONLY GM TKO, ONLY Hydraulic TB
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T5
This is my choice for now. Its 1/2 the weight(80lb) of the TKO(160lb), widespread availability, upgrades, and plenty strong. I picked up a Ford Racing Z-spec version a few months ago at a very reasonably price.
Gear Ratios 1st-5th
2.95, 1.94, 1.34, 1.00, .63
The big issue I have is that the QuickTime bellhousing is TKO ONLY. While most other QT bells are cut for both TKO & T5 trans, the RM4070 for the 3.6L is only made fora GM TKO. Getting a Custom bell from QT would cost an additional $450 on top of the $1099. That was a bit too much for my budget. But I think I found a possible 2nd option.
Since I was going for light weight, the rather hefty QT Bell wasn't optimal but was the only game in town. Also, my T5 would have been a no go or I'd have to spend a couple grand for a TKO. So i took another look at the ONLY other "Bellhousing" on the planet for a 3.6L,,,,,the NAG1 auto
The Jeep NAG1 auto bell is Aluminum, so its very light. Its also readily available and barely $100. So the way I see it, I can put a few hundred dollars in it machining it to bolt on the T5 and still be far ahead in terms of Cost.
There are also numerous "T5 adapter plates" sold to bolt a T5 on to nearly anything. So mounting plates of various thicknesses and offset are available right off the shelf. This means I just need to find the right plate and then get the NAG1 bell cut for the T5 Bearing retainer and 4 mounting bolts. Seems easy enough
I found a "new take off" Bell for just $70 and it's on its way. I'll get it measured to see where the T5 needs to be to properly spaced from the engine.
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