2.5 Automatic Re-Gear

Blake Stamper

TJ Enthusiast
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Boise, Idaho
Okay, I am new to this forum soooo, sorry if I missed it but I'm struggling to figure out what I should regear my 1999 jeep 2.5l automatic and I was wondering if I could get some help?
 
Tire Size is 33 but eventually hoping to go 35s after getting rid of the crappy Dana 35, but I'm a highschooler with limited resources so yeah.
 
Hey there,

Welcome to the forum. I made a thread all about the 2.5L "four bangers", which you can find here. You might find some of the links to be helpful.

If you are running 33s, then yes, you're crossing into the territory of needing to re-gear. At 35s especially. On this forum, you'll find a lot of banter about whether or not it's needed for 31s, but I don't think anyone would argue about 35s.

But, I now see you're not asking whether to regear, but how. For that I'll stay tuned to see what others say!
 
Hey there,

Welcome to the forum. I made a thread all about the 2.5L "four bangers", which you can find here. You might find some of the links to be helpful.

If you are running 33s, then yes, you're crossing into the territory of needing to re-gear. At 35s especially. On this forum, you'll find a lot of banter about whether or not it's needed for 31s, but I don't think anyone would argue about 35s.

But, I now see you're not asking whether to regear, but how. For that I'll stay tuned to see what others say!
Yeah, I know it probably needs a regear I just haven't been able to find out much for an automatic squirrel-powered TJ.
 
Tire Size is 33 but eventually hoping to go 35s after getting rid of the crappy Dana 35, but I'm a highschooler with limited resources so yeah.
Sell it or stick with some aggressive 31" tires. A 4 cylinder auto is like making a bad situation worse. I gave my ex wife a 2.5 auto and even she said it was a gutless piece of shit. I let her keep it since they already had two things in common.💩
Jeep 31s.jpg
 
Use this to plug your information in and then play with different gear ratios to see how it affects your RPM's.

http://www.grimmjeeper.com/gears.html
I had a 4 cyl that I ran for about 4 years before I swapped to a V-8. But I had a manual transmission and have heard more than one person say the 4 cyl w/auto trans SUCKS.
 
Ah, one of the sell it kinda guys, very helpful.
More helpful than you think. You will come back and thank me when you're still not happy after sinking $5,000 into it. You might want to read my entire post. Sometimes people on these forums are here to help you, not be your mama and tell you what you want to hear. Ask people if they ever had a 2.5 auto when they give you "solid" advice. 99.9% NOT.
 
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More helpful than you think. You will come back and thank me when you're still not happy after sinking $5,000 into it. You might want to read my entire post. Sometimes people on these forums are here to help you, not be your mama and tell you what you want to hear.
Sorry, im not trying to be rude or anything like that, my brother has a 4.0 on 35s and it is more of a dog than mine on 33s so I just would rather keep it honestly. I just don't fully agree with the whole idea that if its not the 4.0 than get rid of it because I've seen some really well built 2.5s.
 
More helpful than you think. You will come back and thank me when you're still not happy after sinking $5,000 into it. You might want to read my entire post. Sometimes people on these forums are here to help you, not be your mama and tell you what you want to hear.

He isn't lying or making jokes about your rig. In a JEEP the 4 cyl & auto trans is just a REALLY BAD combo.

Next thing is that your Dana 35 isn't a POS as many say it is. You can make it live with larger tires but you have to spend MONEY to make it live. The best option you have IMO for your situation is to swap in a V-8 but that might be more than you want to do.

Sorry, im not trying to be rude or anything like that, my brother has a 4.0 on 35s and it is more of a dog than mine on 33s so I just would rather keep it honestly. I just don't fully agree with the whole idea that if its not the 4.0 than get rid of it because I've seen some really well built 2.5s.

And the reason your brothers 4.0 w/35" tires is a DOG most likely is due to not being geared properly. The 4.0 isn't a highly powered engine either but it is better than the 2.5. And yes I've seen some really nicely built 2.5's also but with the auto it's just that much worse.

Use the gear calculator to see what differ ratios will get you. Since you don't have a overdrive it makes it that much harder.
 
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Sorry, im not trying to be rude or anything like that, my brother has a 4.0 on 35s and it is more of a dog than mine on 33s so I just would rather keep it honestly. I just don't fully agree with the whole idea that if its not the 4.0 than get rid of it because I've seen some really well built 2.5s.
You're not rude at all. I didn't say that. A 4.0L with 35s and stock gearing is every bit as bad. I was suggesting some nice aggressive 31s and not spending $1500+ regearing it. It's your Jeep and you do want you want and don't give a crap about other people's opinions. I live my life that way. 🤫
RUBI skel 8 26 2 (4).webp
 
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He isn't lying or making jokes about your rig. In a JEEP the 4 cyl & auto trans is just a REALLY BAD combo.

Next thing is that your Dana 35 isn't a POS as many say it is. You can make it live with larger tires but you have to spend MONEY to make it live. The best option you have IMO for your situation is to swap in a V-8 but that might be more than you want to do.



And the reason your brothers 4.0 w/35" tires is a DOG most likely is due to not being geared properly. The 4.0 isn't a highly powered engine either but it is better than the 2.5. And yes I've seen some really nicely built 2.5's also but with the auto it's just that much worse.

Use the gear calculator to see what differ ratios will get you. Since you don't have a overdrive it makes it that much harder.
Okay and thank you for your input, sorry for smarting off at you, it's just I'm looking for keeping my jeep because it's my first one and I really like it I was just trying to get it a little more power and I know its never gonna be a racecar I was just trying to get recommendations on what people suggest.
 
Okay and thank you for your input, sorry for smarting off at you, it's just I'm looking for keeping my jeep because it's my first one and I really like it I was just trying to get it a little more power and I know its never gonna be a racecar I was just trying to get recommendations on what people suggest.
The 4.0L Jeeps suck too. They're fun, so keep it and enjoy it.
 
Okay and thank you for your input, sorry for smarting off at you, it's just I'm looking for keeping my jeep because it's my first one and I really like it I was just trying to get it a little more power and I know its never gonna be a racecar I was just trying to get recommendations on what people suggest.
oops i meant that for boogie man
 
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He isn't lying or making jokes about your rig. In a JEEP the 4 cyl & auto trans is just a REALLY BAD combo.

Next thing is that your Dana 35 isn't a POS as many say it is. You can make it live with larger tires but you have to spend MONEY to make it live. The best option you have IMO for your situation is to swap in a V-8 but that might be more than you want to do.



And the reason your brothers 4.0 w/35" tires is a DOG most likely is due to not being geared properly. The 4.0 isn't a highly powered engine either but it is better than the 2.5. And yes I've seen some really nicely built 2.5's also but with the auto it's just that much worse.

Use the gear calculator to see what differ ratios will get you. Since you don't have a overdrive it makes it that much harder.
Also i know that Dana 35 can have like a super 35 but i got quoted 4400 for a regear and super35 at my local shop so i was planning on getting a ford 8.8 from ecgs.