ratio calculation

[69jeepcj]

I have a question for you guys or gals. My jeep had a warn all range overdrive unit and it went out about a month ago. I have put the tcase back to its stock form so I can at least drive the jeep but with no overdrive. I have a 350hp sbc and 4.88 gears on 35" tires. My question is can someone tell me what my ratio has been reduced to with the 35? and recomendations for top speed with those gears, I would like to drive it on the highway but not sure if I should push it with those gears. I dont have a speedo so I use the flow of traffic and my rpms for now as to how fast I am going. I have taken it on very short highway drives (from one exit to the next) and my rpms where 2500, I would guess my speed was 50-55 as cars were passing me pretty quick. Any Ideas? (meaning we loss some gearing with larger tires, so im wondering what my 4.88,s are eqivilant to with the 35,s, 4.10, 373,ect..)

 

[808CJ7]

Hey Paul. Morris 4x4 Center website has a gear ratio calculator. You need to get the gear ratio of your trans, transfer case, axles and the actual measured hight of your tires to get an accurate calculation of what gears to run. It's going to depend on what you use your jeep for also, daily driver, off road mostly? I'm thinking with the motor and trans. you have now you'll probably do better with a 4:10 gear or a five speed trans. just my opinion. Chris

 

[69jeepcj]

yeah i agree. can.t realy afford either of those right now so thats why I was wondering about what speed if any I should keep it under.

 

[808CJ7]

I know what you mean. I use my IPhone as a speedometer. The one on my jeep is way off. I would say around 2500 rpm is safe. Too bad about the warn overdrive, I hear there very hard to find.

 

[Gennybro]

I know what you mean. I use my IPhone as a speedometer. The one on my jeep is way off. I would say around 2500 rpm is safe. Too bad about the warn overdrive, I hear there very hard to find.

Iphone as a speedometer . How does that work? Guess technology is blowing right past me. Feel stupid asking, but oh well.

 

[Ghost Rider]

Iphone as a speedometer . How does that work? Guess technology is blowing right past me. Feel stupid asking, but oh well.

It uses GPS technology. There is also a app that if you are using head phones, while you are moving faster, the sound gets louder and as you slow down, the volume also gets lower so you don't go deaf at traffic lights....
I am too old for that technology also but my kids are keeping me up to date...Dad there is an app for that. I need an app for reminding me to take my Prozac...... LOL

 

[flatie46]

There's a formula to figure it in The Jeep Bible, and I have a copy...but it's loaned out at the moment. If I might ask, where'd you get the Warn overdrive? They're pretty hard to find.

 

[69jeepcj]

The overdrive was on the jeep when I got it. I was pretty excited about that in itself!!! If you are looking for one, HERM THE OVERDRIVE GUY has them. They are not cheap, around 600-700 bucks for rebuilt one and 900 for new one. If you have one that needs fixed you can send it to him and he will rebuild yours. Its going to be about 400 to fix mine.
Herm is a very nice guy and will talk with you for hours if you need it.
HERM THE OVERDRIVE GUY.COM

 

[flatie46]

The overdrive was on the jeep when I got it. I was pretty excited about that in itself!!! If you are looking for one, HERM THE OVERDRIVE GUY has them. They are not cheap, around 600-700 bucks for rebuilt one and 900 for new one. If you have one that needs fixed you can send it to him and he will rebuild yours. Its going to be about 400 to fix mine.
Herm is a very nice guy and will talk with you for hours if you need it.
HERM THE OVERDRIVE GUY.COM

Thanks for the info. If I happened upon one cheap I wouldn't turn it down but no farther than I have to drive mine (11 miles a day) I prob wont buy one. I just know they're rare and it was a good bonus for ya when you bought the Jeep. I've got a 46 Plymouth with the flathead 6 , I had looked around for an overdrive for it. I ended up making an adapter and putting a T-5 S-10 5speed trans behind it. I'm almost done with it, just started building Jeeps and kinda pushed it to the side. My son's really on me about finishing it, he has a 52 with the flathead. He wants the same setup in his.

 

[69jeepcj]

I think I figured it out, it came out to be 413something to one. 4.88(gears)X2.42(trans)X35(tires). I took it up to 3000rpm,s today, stayed with traffic but didnt like running it that high. Maybe thats not too high but it just sounds high to me. I have read that these 327,s will rev up to 6-7000 rpm,s easly, so maybe 3000 grand won't hurt it at all?? whats your thoughts on where I should keep my top speed. thx