LS Swap Rabbit Hole

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megaman_plums
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LS Swap Rabbit Hole

Post by megaman_plums »

Hey all! I’m going a while since I’ve had an update but figured now is a good a time as any. After my most recent visit to the Jeep that was filled with issues I think I finally come to the decision to go with an LS swap. Obviously it pains me as I would love to have the 401 working right but everything my dad and I have done has proven unsuccessful and I just want to be able to drive my Jeep and actually enjoy it.

I just wanted to have a soundboard here just to confirm a few things. The current breakdown:

1977 Cherokee chief
401 with th400
Quadratrac
Dana 44 front and rear

I terms of actually picking and finding an engine I’m not terribly worried. I was thinking of either going with one of the variations of the 5.3 or LQ4/LQ9. The first problem I run into is that I cannot find anyone who makes an adapter for a Gen III Chevy to meet up to the Jeep version of the th400. I know Novak used to sell the adaptor but I have not been able to find that kit at all anywhere. That would mean switching to a 4l60e or 4l80e. The follow up issue would then be I haven’t been able to find anyone making any parts to convert one of those transmissions to hook up to Quadratrac, which means getting a new transfer case.

So I just wanted to confirm the primary way for me to realistically complete the swap would be new engine, trans and a Dana 18.

I know I could go to a different transfer case but that would mean having to swap axles and that just seems like even more work than there already would be. I know Novak has a adapter kit to hook up in early 4L60, but it seems like if I’m already going through the trouble of having to get a new transmission why don’t I just stick with something I can actually have more computer controls and tuning with.

Like I said, just wanted to hear if anyone else had any possible suggestions or alternative routes before I start figuring out ways to kill my bank account

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Last edited by megaman_plums on Tue Oct 04, 2022 11:58 am, edited 1 time in total.
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dodgerammit
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Re: LS Swap Rabbit Hole

Post by dodgerammit »

Is there a reason you couldn't use a GM specific 400 trans and then run the quadratrac?

2nd option is the 700R4 and this: https://www.advanceadapters.com/700r-4- ... uadra-trac

I understand the desire for many to have a newer transmission, but have read issues of getting everything to work with speedo/speed sensor, etc.

Every time I read those issues, I just smile because I kept the fresh 727 in mine. Many on the fakebook swap pages just pooed on the 727 and gave all sorts of lame reasons (just hearsay, because nobody had actually any experience) it wouldn't work.

I ditched all the wiring for the electronic trans and ran my speedo cable from the case to the speedo like factory. No sensors. No reprogramming. No issues.

My 2 cents is this: If I'm going to replace the trans with a different one, it's getting inspected/rebuilt at that time. No questions. I don't trust any auto transmission I haven't owned for a length of time. Maybe it's different elsewhere, but here in BFE Hickville, nothing gets serviced. If it does, it's by the hack owner who shouldn't touch tools, or an inept "mechanic", so I always expect the worst. Usually, I'm not wrong.
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Yeller
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Re: LS Swap Rabbit Hole

Post by Yeller »

Lots of options. You could pick up core turbo 400 and change the case. I have a converter snout ring I'd mail you if you go this route, also have a D20, t400 output shaft, and adapter that I'd send you for the cost of shipping if you wanted away from the quadratrac. The simplest route if you want overdrive is to go to a 2wd 4l80e from an RV or van, they have a fully splined output shaft that can be cut to the correct length, the rear speed sensor is in the case on a 2wd, allowing you to run any transfer case that has a 32 spline input with a mechanical speedometer. 700r4 is an option as well, I have one behind a 5.3, it is ok, but it shifts too early, even with a corvette valve body, governor and servo's and converter lockup control is terrible, really wish I had done a 4l60e. If you do a transfercase without a mechanical speedo Speedhut does sell a speedometer drive that works very well converting a VSS signal to a mechanical drive.

Couple of things to do to the donor motor, based on my experience with swapping many of them. Plan on changing the water pump, pan gasket, timing cover gasket and seal, rear main cover and seal, and valve cover gaskets. also don't skimp and not use an alignment tool for the timing and rear cover to prevent leaks. Nothing is worse than getting it put in and a week later it needs a water pump, and the rear main cover is leaking...... Only had the rear main leak on 1, but its $20 and 30 minutes to change it before it goes in, once its in, it has to come back out or the transmission comes out. I'm 0 for 12 on water pumps lasting the test drive, even on motors that I pulled from running, driving vehicles and immediately installed.

My current truck is an LQ4/4l80e/241c. I'm very happy with it other than my 241c has a cracked case and leaks. After pricing getting a core, rebuilding it, adding a slip yoke eliminator, if I paid myself labor, I was within a couple of hundred dollars of an Atlas, I just ordered a 3.0 Atlas and not looking back. not the least expensive option but in my opinion the best option for my brain, and my use of the truck.

For reference, here's the info on the mechanical speedo drive for anyone interested. Not cheap but it works well.
https://speedhut.com/categories/speedbox.html
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Stuka
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Re: LS Swap Rabbit Hole

Post by Stuka »

I would not consider using a D18 behind an LS a good idea. There was issues with D18 reliability behind anemic i6 engines, which is why the D20 came around.

The D20 is also not the best option, but it will survive if you don't abuse it. And sadly, I think an NP case is not an options due to the much longer case which would result in more of a drive shaft angle with the offset rear axle. Which its worth noting the rear axle you have was the same for the D20 and QT equipped models (only the case for WT and J-Trucks).

As far as I know, you can put a QT on the back of a GM TH400 if you swap the rear output shaft out, but I would need to dig around some to see if anybody else has done that. But I think it would be the cheapest route for you to go.

Though before going that route, it would be good to find out the current condition of your QT. No point in going through all the work to keep it, just to find out its toast.
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thej10guy
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Re: LS Swap Rabbit Hole

Post by thej10guy »

For a transfercase and keeping stock axles, you could use the transfercase out of a 88-91 square body chevy. It will bolt up to the transmission and would have the passenger side drop. I have an 83 j10 that I am doing the swap in, and picked up an 89 GMC Jimmy (full size) and was going to put that transfercase in it so I could run the axles out of my 79 j10 but decided against it because we didn’t want to do the axle swap (yet).


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tgreese
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Re: LS Swap Rabbit Hole

Post by tgreese »

Comment on the Dana 18 - in the V6 Jeeps, its main issues are durability and noise.

The intermediate shafts and bearings wear out quickly. When introduced, the WWII version had a very small 3/4" diameter shaft, which was quickly replaced by a 1 1/8" version in civilian use. Later it went to a 1 1/4" diameter shaft, which is referred to as the "big hole case." It is possible to break the case from impact load (I presume) and you can build a big hole Dana 18 in a somewhat stronger Dana 20 case. There is or was an aftermarket girdle that bolts to the bottom of the case to strengthen it.

There are things to know when rebuilding a Dana 18. First, the intermediate shaft and bearings from the usual aftermarket suppliers do not last. (Lots in common with the Quadratrac here - in both cases the intermediate gear or chain is driving the rear wheels all the time, and it wears out). If you stay with the original intermediate shaft design, a higher-quality hardened shaft and bearings from Novak or HermTheOverdriveGuy is a must. You can also buy a kit from Advanced Adapters to convert from the loose bearings to a tapered bearing (like a wheel bearing), but it requires machining the case to accommodate the new design.

Next, the Dana 18 is noisy. The gears are driven all the time, and there is a constant gear whine. When introduced, the Dana 20 was touted as the "silent transfer case" for this reason. The intermediate gear in a 20 is not driven on the highway, unlike the 18.

Any Dana 18 you find will be no newer than 1971. And they leak - you'll find thread after thread on the early CJ and flat fender forums about ways to make them leak less. Other than that, they are great.

If you want to build a D18 for your Cherokee, there are dozens of threads on earlycj5.com addressing these issues. Novak has a chart showing the versions and gear numbers for all generations of 18 and 20, which you should refer to so you know what you have.

Interesting that Stuka cites the length of the NP cases as reason to go with the 20. I'd think the Dana 300 would be the superior alternative if the 20 is ok. Demand is high for the 300; you should be able to source several 18s or 20s for the cost of a 300. But they are out there, passenger drop like the 18 and 20, come with a NP pattern typically, and are well supported in the aftermarket.

PS - I'd also reject the TH400. You may as well keep the AMC engine if you don't get rid of the inefficient legacy automatic. They are smooth, strong, reliable and durable, but way less efficient than a modern overdrive automatic.
Last edited by tgreese on Sat Dec 17, 2022 2:57 pm, edited 1 time in total.
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Re: LS Swap Rabbit Hole

Post by dodgerammit »

Yeller wrote: Tue Oct 04, 2022 6:16 am
Couple of things to do to the donor motor, based on my experience with swapping many of them. Plan on changing the water pump, pan gasket, timing cover gasket and seal, rear main cover and seal, and valve cover gaskets. also don't skimp and not use an alignment tool for the timing and rear cover to prevent leaks. Nothing is worse than getting it put in and a week later it needs a water pump, and the rear main cover is leaking...... Only had the rear main leak on 1, but its $20 and 30 minutes to change it before it goes in, once its in, it has to come back out or the transmission comes out. I'm 0 for 12 on water pumps lasting the test drive, even on motors that I pulled from running, driving vehicles and immediately installed.
Agreed on the seals. Sac city corvette has inexpensive alignment tools. I used one on my T/A.

Add to that the famous oil pump pickup O ring.
84 Grand Waggy-Radio Flyer (Garnet Red/3M Ebony Metallic woodgrain, with honey interior) AMC 360 :cry: 2004 4.8LS/Advance Adapter/727/242 D44/AMC20 Serehill tailgate and headlight harnesses :fsj: Ongoing thread-viewtopic.php?t=11897

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Re: LS Swap Rabbit Hole

Post by Stuka »

tgreese wrote: Tue Oct 04, 2022 9:28 am Interesting that Stuka cites the length of the NP cases as reason to go with the 20. I'd think the Dana 300 would be the superior alternative if the 20 is ok. Demand is high for the 300; you should be able to source several 18s or 20s for the cost of a 300. But they are out there, passenger drop like the 18 and 20, come with a NP pattern typically, and are well supported in the aftermarket.
Yeah, a D300 is also a viable option, but they are more costly. But they use the NP round pattern so are easy to adapt to.

A chain driven NP case may work ok, it just results in a shorter rear drive shaft, which will make the u-joints run at a steeper angle. Perfectly fine for a J-Truck as its rear shaft, even on a shortbed, is 10" longer.
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megaman_plums
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Re: LS Swap Rabbit Hole

Post by megaman_plums »

Yeller wrote: Tue Oct 04, 2022 6:16 am Couple of things to do to the donor motor, based on my experience with swapping many of them. Plan on changing the water pump, pan gasket, timing cover gasket and seal, rear main cover and seal, and valve cover gaskets. also don't skimp and not use an alignment tool for the timing and rear cover to prevent leaks. Nothing is worse than getting it put in and a week later it needs a water pump, and the rear main cover is leaking...... Only had the rear main leak on 1, but its $20 and 30 minutes to change it before it goes in, once its in, it has to come back out or the transmission comes out. I'm 0 for 12 on water pumps lasting the test drive, even on motors that I pulled from running, driving vehicles and immediately installed.

My current truck is an LQ4/4l80e/241c. I'm very happy with it other than my 241c has a cracked case and leaks. After pricing getting a core, rebuilding it, adding a slip yoke eliminator, if I paid myself labor, I was within a couple of hundred dollars of an Atlas, I just ordered a 3.0 Atlas and not looking back. not the least expensive option but in my opinion the best option for my brain, and my use of the truck.

For reference, here's the info on the mechanical speedo drive for anyone interested. Not cheap but it works well.
https://speedhut.com/categories/speedbox.html
I was planning on rebuilding/refreshing all the new parts and pieces when they arrived. Far easier to do that stuff when its out the Jeep than in it.

I had heard about the 241c but everything I had seen was that it was a passenger front/center rear. I know some people are ok with the center to rear offset and others aren't but I just don't see too many people posting about it. And an Atlas would be amazing but I am not planning on anything serious in terms of offroading.

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Re: LS Swap Rabbit Hole

Post by megaman_plums »

Stuka wrote: Tue Oct 04, 2022 7:01 am I would not consider using a D18 behind an LS a good idea. There was issues with D18 reliability behind anemic i6 engines, which is why the D20 came around.

The D20 is also not the best option, but it will survive if you don't abuse it. And sadly, I think an NP case is not an options due to the much longer case which would result in more of a drive shaft angle with the offset rear axle. Which its worth noting the rear axle you have was the same for the D20 and QT equipped models (only the case for WT and J-Trucks).

As far as I know, you can put a QT on the back of a GM TH400 if you swap the rear output shaft out, but I would need to dig around some to see if anybody else has done that. But I think it would be the cheapest route for you to go.

Though before going that route, it would be good to find out the current condition of your QT. No point in going through all the work to keep it, just to find out its toast.
Got it. And as far as I am aware my QT is in ok shape besides some minor leaking, but then again what isn't leaking on this Jeep.

I know my dad thinks the best route would be to get the early 4l60 and just use one of the adaptors to connect it to the QT. Get one of the Mile Marker adapters to help things as well.
Last edited by megaman_plums on Tue Oct 04, 2022 2:06 pm, edited 1 time in total.
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Re: LS Swap Rabbit Hole

Post by Yeller »

megaman_plums wrote: Tue Oct 04, 2022 12:01 pm
I had heard about the 241c but everything I had seen was that it was a passenger front/center rear. I know some people are ok with the center to rear offset and others aren't but I just don't see too many people posting about it. And an Atlas would be amazing but I am not planning on anything serious in terms of offroading.
It is a center rear output. It would require a slip yolk eliminator, and a standard single ujoint and not a CV at the tcase. In my opinion, stock height up to about 2-1/2” of lift you’ll be fine. Yes mine is in a truck but has a Dana 60 and a really long slip yoke eliminator that is 8” longer than a normal one, so the driveshaft is the same length as it would be in your wagon.
The bus I ride is so short it is a yellow Smart Car full of squirrels, monkeys and clowns.

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Re: LS Swap Rabbit Hole

Post by supergeess »

Yeller wrote: Tue Oct 04, 2022 6:16 am Lots of options. You could pick up core turbo 400 and change the case. I have a converter snout ring I'd mail you if you go this route, also have a D20, t400 output shaft, and adapter that I'd send you for the cost of shipping if you wanted away from the quadratrac. The simplest route if you want overdrive is to go to a 2wd 4l80e from an RV or van, they have a fully splined output shaft that can be cut to the correct length, the rear speed sensor is in the case on a 2wd, allowing you to run any transfer case that has a 32 spline input with a mechanical speedometer. 700r4 is an option as well, I have one behind a 5.3, it is ok, but it shifts too early, even with a corvette valve body, governor and servo's and converter lockup control is terrible, really wish I had done a 4l60e. If you do a transfercase without a mechanical speedo Speedhut does sell a speedometer drive that works very well converting a VSS signal to a mechanical drive.

Couple of things to do to the donor motor, based on my experience with swapping many of them. Plan on changing the water pump, pan gasket, timing cover gasket and seal, rear main cover and seal, and valve cover gaskets. also don't skimp and not use an alignment tool for the timing and rear cover to prevent leaks. Nothing is worse than getting it put in and a week later it needs a water pump, and the rear main cover is leaking...... Only had the rear main leak on 1, but its $20 and 30 minutes to change it before it goes in, once its in, it has to come back out or the transmission comes out. I'm 0 for 12 on water pumps lasting the test drive, even on motors that I pulled from running, driving vehicles and immediately installed.

My current truck is an LQ4/4l80e/241c. I'm very happy with it other than my 241c has a cracked case and leaks. After pricing getting a core, rebuilding it, adding a slip yoke eliminator, if I paid myself labor, I was within a couple of hundred dollars of an Atlas, I just ordered a 3.0 Atlas and not looking back. not the least expensive option but in my opinion the best option for my brain, and my use of the truck.

For reference, here's the info on the mechanical speedo drive for anyone interested. Not cheap but it works well.
https://speedhut.com/categories/speedbox.html
I did same as Yeller...LQ9, 4L60E, 241...bought everything form one wrecking yard with ECM, harness, and DBW pedal. Used my stock D44 axles for years with no issues at all, then upgraded to D60 and Corp14. Dakota Digital gauges for me.
1977 Chief: LS1 6.0, 4L60E, NP241, SYE, Dakota Digital gauges, more to come.

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Re: LS Swap Rabbit Hole

Post by sierrablue »

I'm not sure I understand the issues with the Dana 20--it's plenty strong, and gear driven, and it's fairly light. But if you have a Quadratrac, and are looking to swap, the only reason I'd consider the D20 is if you wanted to keep it stock but didn't want the full-time 4x4 (due to mileage and drivability as a daily driver).

Ditto on the LS w/o overdrive--there's no reason for the LS swap if you're not putting in an overdrive too. The '88 I had had the 401, TBI fuel injection, and the 727 still, but I was looking at swapping a '95 Grand Cherokee overdrive transmission behind it (yes it's electronically controlled, and yes it's fairly weak out of the box--but in reality it's a 727 with electronic controls and an overdrive--you can make it plenty strong). Depending on the problems you're having and how you're planning on using it, I'd probably just fuel inject the 401.

Just my personal opinion--an LS is cheap and easy but not the best upgrade. It's still a pushrod V8--sure, it's fuel injected and easier to work on, but still a pushrod V8. If I were gonna swap, I'd look for SOHC or DOHC, but that's just me.

What problems are you having with the 401?

The truck looks really good!
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-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

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There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.
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