Questions about Borg Warner T18 transmission swap

[KarlTJ]

Hello!, my name is Karl I live in Quito Ecuador, and wanted to ask from the Jeep guys a question. I live in Quito Ecuador and I'm after a Jeep TJ 4.0L, I found one that is in very good condition but the problem is that it had a transmission swap. If you guys could help me out with some questions I would be highly appreciated. It originally had an automatic transmission but it was swapped to a manual It now has a borg warner t18 transmission, It has a crown and cone Yukon 30 35 relation 4 88
But... it drives like a truck its super-strong has lots of torque but almost no speed and I want to use the car for my day to day basis, driving to the university some 4 wheeling and going out with friends

So my questions are...

1. Does a transmission swap affect negatively the jeep?
2. How good is the transmission Borg Warner t18 for a TJ
3. Only by changing the crown and cones will I be able to get more speed and less torque?
4. How safe would it be for the jeep to do another swap but to the OEM manual transmission

 

[Chris]

I've been into TJs for a long time and never once heard about a Borg Watner T18 swap.

How does that even mate up to a 4.0 without some sort of adapter. Why would someone even do this?

If it works, keep it, there's no reason to fix it if it isn't broke. If you're insisting on swapping in another transmission, the AX-15 is considered the go-to choice for manual transmission swaps.

 

[Rubicon88]

I've been into TJs for a long time and never once heard about a Borg Watner T18 swap.

How does that even mate up to a 4.0 without some sort of adapter. Why would someone even do this?

If it works, keep it, there's no reason to fix it if it isn't broke. If you're insisting on swapping in another transmission, the AX-15 is considered the go-to choice for manual transmission swaps.

It mates up very simple.

All someone needs is a BH from a 76-86...
that was in front of a T150, or a (jeep T18) then later a T176 ... and the jeep or Ford T18 will bolt right up to that BH...which that BH can interchange from 232 I6 , all the V8's, the 258 six, and of course what we have in the 4.0
It bolts up beautifully to all those.

Being a T18 the final drive gear is 1:1 as there is no 5th gear.

He also claims lower R&P at 4.88:1

Hello!, my name is Karl I live in Quito Ecuador, and wanted to ask from the Jeep guys a question. I live in Quito Ecuador and I'm after a Jeep TJ 4.0L, I found one that is in very good condition but the problem is that it had a transmission swap. If you guys could help me out with some questions I would be highly appreciated. It originally had an automatic transmission but it was swapped to a manual It now has a borg warner t18 transmission, It has a crown and cone Yukon 30 35 relation 4 88
But... it drives like a truck its super-strong has lots of torque but almost no speed and I want to use the car for my day to day basis, driving to the university some 4 wheeling and going out with friends

So my questions are...

1. Does a transmission swap affect negatively the jeep?
2. How good is the transmission Borg Warner t18 for a TJ
3. Only by changing the crown and cones will I be able to get more speed and less torque?
4. How safe would it be for the jeep to do another swap but to the OEM manual transmission

Karl...

What size tire are you running?
I'd be willing to bet it's smaller and you're running out of engine ram.

That t18 has no overdrive gear and first is too low for the street. (If it's the low gear version) You start out in second gear.

I see you are 19 years old...a t18 is NOT driven like forza. I mean no disrespect in saying that but you don't launch in first gear and expect to scream it slamming it into second gear.

This tranny you start out in second gear, and shift it nice and slow. It has a long throw to it and you definitely don't try power shifting it need for speed style.

If the conversion was done right you'll really gave no idea how lucky you are to find such a conversion if done right.
That tranny is stronger than any of Jeeps manuals...ever. not even close.

It's tremendous on the trail. Won't ever break. Shift it the way it's meant to be shifted and it will out live the vehicle.

 

[Cross-Threaded-06TJ]

Hello!, my name is Karl I live in Quito Ecuador, and wanted to ask from the Jeep guys a question. I live in Quito Ecuador and I'm after a Jeep TJ 4.0L, I found one that is in very good condition but the problem is that it had a transmission swap. If you guys could help me out with some questions I would be highly appreciated. It originally had an automatic transmission but it was swapped to a manual It now has a borg warner t18 transmission, It has a crown and cone Yukon 30 35 relation 4 88
But... it drives like a truck its super-strong has lots of torque but almost no speed and I want to use the car for my day to day basis, driving to the university some 4 wheeling and going out with friends

So my questions are...

1. Does a transmission swap affect negatively the jeep?
2. How good is the transmission Borg Warner t18 for a TJ
3. Only by changing the crown and cones will I be able to get more speed and less torque?
4. How safe would it be for the jeep to do another swap but to the OEM manual transmission

1. Swapping to a factory 5 speed Jeep transmission like and AX15 will not negatively affect anything. Other than cost you money.
2.The T18 is the strongest 4 speed ever installed into a Jeep. Especially if you have the wide ratio with the 6.32 first gear.
3.Yes, if you changed your "crown and cones" to a lower number you will regain speed and lose torque.
4.Its perfectly safe to swap in another transmission of the same year range.

 

[KarlTJ]

It mates up very simple.

All someone needs is a BH from a 76-86...
that was in front of a T150, or a (jeep T18) then later a T176 ... and the jeep or Ford T18 will bolt right up to that BH...which that BH can interchange from 232 I6 , all the V8's, the 258 six, and of course what we have in the 4.0
It bolts up beautifully to all those.

Being a T18 the final drive gear is 1:1 as there is no 5th gear.

He also claims lower R&P at 4.88:1


Karl...

What size tire are you running?
I'd be willing to bet it's smaller and you're running out of engine ram.

That t18 has no overdrive gear and first is too low for the street. (If it's the low gear version) You start out in second gear.

I see you are 19 years old...a t18 is NOT driven like forza. I mean no disrespect in saying that but you don't launch in first gear and expect to scream it slamming it into second gear.

This tranny you start out in second gear, and shift it nice and slow. It has a long throw to it and you definitely don't try power shifting it need for speed style.

If the conversion was done right you'll really gave no idea how lucky you are to find such a conversion if done right.
That tranny is stronger than any of Jeeps manuals...ever. not even close.

It's tremendous on the trail. Won't ever break. Shift it the way it's meant to be shifted and it will out live the vehicle.

Its running BFGoodrich KM2 35" but I was thinking about going down to a 32" in order to get more speed without causing the engine to rev so high without forcing the engine since I would use it on a daily basis at a commute of about 40min drive on a highway. My off-roading is limited to mud and mountains about 3-4 times a month

 

[KarlTJ]

1. Swapping to a factory 5 speed Jeep transmission like and AX15 will not negatively affect anything. Other than cost you money.
2.The T18 is the strongest 4 speed ever installed into a Jeep. Especially if you have the wide ratio with the 6.32 first gear.
3.Yes, if you changed your "crown and cones" to a lower number you will regain speed and lose torque.
4.Its perfectly safe to swap in another transmission of the same year range.

As I mentioned I have it has 4:88 gears... If bringing it down to the stock Sahara crown and cone or probably even lower will I maintain good power and loosen the force on the engine? Because I would not like to go faster having a risk of blowing the engine

 

[Cross-Threaded-06TJ]

As I mentioned I have it has 4:88 gears... If bringing it down to the stock Sahara crown and cone or probably even lower will I maintain good power and loosen the force on the engine? Because I would not like to go faster having a risk of blowing the engine

4.88 gears and 35" tires would be fine if you had overdrive (5th gear). If you are going to change the "crown and cones" with your current transmission then choose 4.10 gears if you want to go faster with less RPM. Or do the redneck thing and install even bigger tires.

 

[Rubicon88]

Its running BFGoodrich KM2 35" but I was thinking about going down to a 32" in order to get more speed without causing the engine to rev so high without forcing the engine since I would use it on a daily basis at a commute of about 40min drive on a highway. My off-roading is limited to mud and mountains about 3-4 times a month

If you drop to a 32 you'll have more rpm. That would be a pretty quick jeep with 4.88:1 and 32's.

Do NOT change the tranny. If done right that is a bad ass machine.