Consensus on 6BT in FJ80 without AWD (1 Viewer)

[lostih]

Well...it looks like I might be getting back in the 80 series diesel group. After completing the 4bd1t swap in my 94 I decided to venture to the darkside with a 100 series. Once again I find myself wanting to lose sparkplugs and go diesel and just picked up a triple locked truck with a blown head gasket. I've been reading up on the recent builds and folks seem to have made a ton of progress on the 6bt's. I didn't like having a custom adapter in my last build so I'm thinking of trying to use a stock 6bt/5spd/NP205 combo. So here's the two questions bugging me right now that I haven't got a clear answer on:

1. How does the stock rear end hold up with low power 6bt's (meaning sub 250hp) if you use a splitcase, 205 or ? that causes you to lose AWD? Lots of people seem to worry about this, but has anyone put say 10k miles on one to find out?

2. And has anyone actually run a NP205 or other centered output transfercase on either gas or diesel using the stock offset rear end to see if the stock fuel tank is an issue? I assume it must be as the couple I found have moved the tank, but they were also running centered diffs. I'm just curious if you run enough lift for 37's could you also run the centered 205 with the stock cruiser axle and have enough driveline clearance? Alternatively using a tank mounted where the spare used to go seems like a reasonable tradeoff for not having to monkey with adapters. I like the build that mounted an air tank in that spot...

Thanks for any experiences you can share!

 

[LINUS]

Title means you want to glowplug a <'93 80 but gets murky in the post.

The same Yota 3rd is present in all years (9.5") - but later means full float over semi, as I bet you are familiar.

From there - not sure what you are worried about, but I know the 205 case however I've really only seen (maybe I only paid attention to-) -swaps that went from a motor to a bellhousing swap there.

Had a old 350/205 in a blazer, was OK. But that was my "poor kid years". Once sold I went to a minitruck with a turbo, then from there the 80.

Is there a reason not to use an adapter & get a Yota powertrain back in play ASAP after the transplant motor?

 

[lostih]

sorry if it was unclear. I'm planning to go 6bt and would like to do a manual. My least favorite part of my last swap was having a custom adapter in it...so doing something close to a stock dodge drivetrain from crank to driveshaft sounds appealing. However, reading some of the builds it sounds like people were worried that the 9.5" rear end wouldn't take the torque of the cummins without AWD splitting some of that torque to the front axle. Mr Cimmarron seems to be doing just fine with it though. Maybe a non issue.

Anyone using a 205 or other centered rear output case with a stock 80 offset axle?

 

[maxamillion2345]

I think if you're not beating on it the rear will hold.

Can't say on the DL clearance with certainty but I suspect you may be able to clear.

I'd suggest a NV4500 and a 2nd gen 12valve, I wouldnt hesitate to run a np241hd either but I can understand the appeal of a 205.

 

[DIESELJEEP]

I used a 12v+getrag+np205 for my swap.Using the stock off-center rear end.Only 600 miles on the conversion so far but it seems to be holding up fine.The centered tcase and off-center rear play nice together.No vibration.I did have to replace/relocate my fuel tank to the rear. The pump is turned up a bit and I've put the driveline through the paces,cutting up spinning tires (37's) and just all around driving it hard.So I think the stock rear will be fine behind a mild cummins

 

[lostih]

I wouldnt hesitate to run a np241hd either but I can understand the appeal of a 205.

Thanks for the info. Your build has got me thinking about this path seriously. I'm learning as fast as I can about the dodge parts. Is there a version of the 241 that has a passenger side front output? I was thinking they only came in second gen dodges with the drivers side drop.

 

[lostih]

I used a 12v+getrag+np205 for my swap.Using the stock off-center rear end...So I think the stock rear will be fine behind a mild cummins

This is exactly what I'm thinking of doing! Great info! How are your rpms with the getrag at say 70?

 

[DIESELJEEP]

This is exactly what I'm thinking of doing! Great info! How are your rpms with the getrag at say 70?

Tach isn't functioning as of now but the motor seems happy around 70 and can be pushed to 90 but its wound tight by then

 

[lostih]

Tach isn't functioning as of now but the motor seems happy around 70 and can be pushed to 90 but its wound tight by then

Do you have any pics of the underside that you could post? I'm curious to see how the 205 it's up in the tunnel.

In your registry post I see the firewall flex was a problem for you. How did you fix it?

 

[lostih]

Sorry one other question, have you worked out the speedo?

 

[DIESELJEEP]

Sorry one other question, have you worked out the speedo?

Yea speedo works fine,although its off by 10mph.Just had to mix and match the two gear driven units at the tcase.Needed to make a little square shaft to mate the two

 

[DIESELJEEP]

Do you have any pics of the underside that you could post? I'm curious to see how the 205 it's up in the tunnel.

In your registry post I see the firewall flex was a problem for you. How did you fix it?

Yea been meaning to post some pics.I'll try and get some up for you.But it fits well and I'm sure a cable shifter would make a cleaner look for the tcase.I used the stock (dodge)shifter and cut a large hole to fit everything.I just plated the firewall to add rigidity.I thought I had a faulty slave/master cylinder.It took me a bit to figure out what was going on so I mentioned it in case someone else tried and had issues

 

[DIESELJEEP]

Do you have any pics of the underside that you could post? I'm curious to see how the 205 it's up in the tunnel.

In your registry post I see the firewall flex was a problem for you. How did you fix it?

Hope these help ya

 

[lostih]

Hope these help ya

They sure do! Thank you! Is that the stock cross member with a spacer in it? Were you able to keep it in the stock location? Using mechanical fan or electric up front?

Thanks again...these are super helpful. I'm either going to do what you have here or see if I can go with a NV4500/NP241 combo for the 2.72 tcase low range. I want to keep it simple though...and this set up looks pretty straightforward.

 

[DIESELJEEP]

No worries glad to help.It is the stock cross member,had to add the spacer to keep the tcase out of the floor.Had to drill it to fit the tcase mount as it didn't line up just right.Used electric fan but was only lacking a bit of room to mount the mechanical fan.I have an after market radiator also,so it might be doable with a different radiator.

I've done a few drivetrain swaps,this was one of the easier ones.Besides the weight and just moving these cummins engine around!

 

[lostih]

Awesome. Thanks again for these pics. I've done a couple swaps as well and would like to see what can be done without adapters and as clean as possible. We'll see where we end up

 

[maxamillion2345]

Thanks for the info. Your build has got me thinking about this path seriously. I'm learning as fast as I can about the dodge parts. Is there a version of the 241 that has a passenger side front output? I was thinking they only came in second gen dodges with the drivers side drop.

Oh shoot! You're right! Totally skipped my mind.

 

[lostih]

Oh shoot! You're right! Totally skipped my mind.

Turns out we are both right 89-91 Chevy suburbans used a NP241 with a passenger side drop. It has a different spline input shaft, but the 2.72 low range and quite chain drive make me think its worth swapping the input shafts to get quite and almost 3:1 low range...

 

[lostih]

also 89-93 dodge gassers used the NP241 with a passenger side drop. Don't know what their input shaft was though...

 

[mjosoba]

I think the dodge gasser 241 was 27 spline. Could swap dodge gas nv4500 mainshaft in, and keep the diesel nv4500 input so it would still bolt up.