2.5L upgrade...

[Stoopid Jeep]

I have 4:10 with 31’s and 55 is difficult to get to at the on ramp of the freeway. I guess it must make that much of a difference huh? I never use 5th either.

Yeah, it makes a huge difference. After I got the 31's my jeep still had 4.10 gears, it was terrible. I hated it and almost sold it. It's much better now, even better than stock. I use 5th all the time, it will go up hills, and keep up with traffic, and it's even better off road. New gears made the jeep more fun. ..and that's the whole point of a jeep, isn't it?

 

[Flyer58]

Any recommended brand for the kits? I've done this before on other cars and will not be looking forward to doing the work. They seem to be running $500-$600+ for both.

 

[Stoopid Jeep]

Don't know how much it matters. I used elite and they set up fine, good pattern, no noise. I definitely wouldn't cheap out on bearings though, Timken or SKF.

 

[gixxerkid3]

Yeah, it makes a huge difference. After I got the 31's my jeep still had 4.10 gears, it was terrible. I hated it and almost sold it. It's much better now, even better than stock. I use 5th all the time, it will go up hills, and keep up with traffic, and it's even better off road. New gears made the jeep more fun. ..and that's the whole point of a jeep, isn't it?

That’s what I needed to hear. Thanks for the input

 

[T-Rex Jeepster]

My 2.5 will run 85mph, exactly how fast do you think a jeep needs to go?

Till it sees a hill coming........

 

[T-Rex Jeepster]

This may seem like a dumb question, but I'm just thinking outside the box for when someday my YJ needs a heart transplant. Why does no one ever try to install a hopped up 4cyl? With all the hi performance 4 bangers out there, it would seem that one could be adapted to fit. Chevy 350s and the 4.0 seem like common transplants but seem to need the replacement of all sorts of extraneous parts to handle the added HP.

Has anyone seen or heard of a built jeep 2.5L?

I swapped a '94 4.0 into a '95 YJ that had a 2.5, In short, NEVER AGAIN, It's a Chrysler product Ergo, NOTHING interchanges....Just get a nice V-6 or better yet a small block 4.7 or 5.3 and
drive responsibly. I had to go with a 3.07 gear on 31's and am disappointed with the power on highways so I'm looking to Super Charge the 4.0 to get it to the performance level I like. As far as adapting something to another, These guys are King.........

Novak Jeep Conversions - Home

Novak Engine & Transmission Conversions for Jeeps

www.novak-adapt.com

 

[machoheadgames]

I swapped a '94 4.0 into a '95 YJ that had a 2.5, In short, NEVER AGAIN, It's a Chrysler product Ergo, NOTHING interchanges....Just get a nice V-6 or better yet a small block 4.7 or 5.3 and
drive responsibly. I had to go with a 3.07 gear on 31's and am disappointed with the power on highways so I'm looking to Super Charge the 4.0 to get it to the performance level I like. As far as adapting something to another, These guys are King.........

Novak Jeep Conversions - Home

Novak Engine & Transmission Conversions for Jeeps

www.novak-adapt.com

the fact still is and always will remain that 3.07 gears suck. You killed what performance the 4.0 had by doing that….drive mine for comparison and comsidering 180 Hp & 220 tq, it’s relatively a bat out of hell. You are geared taller than any factory setup ever came. The 4.0 YJ came with 27’s and 28’s and the 28’s got 3.55. 3.07 on 31’s is terrible.

4.10 is a MUCH better match for 31’s with the AX15. That’s how the TJ Rubicon came factory and it was a great setup, well liked by many.

As for 4.0 vs 2.5, they are very similar besides engine mount location, fan shroud/hoses, and bellhousing and of course the exhaust and intake. But for engine management, you can buy stock harnesses and PCMs off eBay and make it plug and play….doesn’t have to be a hard swap. The benefit to 4.0 from a 2.5 is it has the OEM support. Any other V6 or V8 will require more custom work.

 

[T-Rex Jeepster]

the fact still is and always will remain that 3.07 gears suck. You killed what performance the 4.0 had by doing that….drive mine for comparison and comsidering 180 Hp & 220 tq, it’s relatively a bat out of hell. You are geared taller than any factory setup ever came. The 4.0 YJ came with 27’s and 28’s and the 28’s got 3.55. 3.07 on 31’s is terrible.

4.10 is a MUCH better match for 31’s with the AX15. That’s how the TJ Rubicon came factory and it was a great setup, well liked by many.

As for 4.0 vs 2.5, they are very similar besides engine mount location, fan shroud/hoses, and bellhousing and of course the exhaust and intake. But for engine management, you can buy stock harnesses and PCMs off eBay and make it plug and play….doesn’t have to be a hard swap. The benefit to 4.0 from a 2.5 is it has the OEM support. Any other V6 or V8 will require more custom work.

Heard it before....And still not down with it.......Gear too tall?

 

[machoheadgames]

Heard it before....And still not down with it.......Gear too tall?


View attachment 119226

Add all the power you want, the 3.07s will still suck. You can put a V8 on it, it will still be a V8 held back from its potential. But you do you.

 

[T-Rex Jeepster]

Add all the power you want, the 3.07s will still suck. You can put a V8 on it, it will still be a V8 held back from its potential. But you do you.

As always.....Applications, Applications, Applications.......

 

[machoheadgames]

As always.....Applications, Applications, Applications.......

Don’t know what that means. There is no application where a 4.0 “needs” tall gears, because in all of them it falls on its face. If you prefer a low rpm yourself then that’s you, but that doesn’t mean your situation needed 3.07. But of course, everyone is free to do as they please.

 

[T-Rex Jeepster]

Don’t know what that means. There is no application where a 4.0 “needs” tall gears, because in all of them it falls on its face. If you prefer a low rpm yourself then that’s you, but that doesn’t mean your situation needed 3.07. But of course, everyone is free to do as they please.