I'm modifying my I6 by putting in an offy/holley deal with a reman cylinder head and headers. It's on a 1984 f150 automatic. I was thinking of lifting it like 3" also. Anyway, I still have the stock rear end and I was wondering what I should do to it in order to follow the modifications I am doing.

Sould I leave it stock? If not, what should I put there and where can I find that? I don't know much about rear end drivetrain!

Thanks

 

If you want something for off-roading or towing, the best would be a 4.10 rear end. If you want better highway performance and better fuel economy, go with 3.05. If you want the best of both worlds you might want to try 3.55. I have 3.55 in my 2wd F150 with the 4.9L and it hauls well, but still gets 20mpg on the highway. Just depends on what your purpose is.

 

i think i see the picture. So for my intents, i would go with a higher ratio. Now, what exactly does that mean? Do I change the axle? the differential? the gears inside? drive shaft?

How does it work??

Sorry, I really dont know much abour rear ends!

Thanks a lot!

 

The first thing is that, in my opinion, you should decide if you want to put the lift in there. If so, then what size tires are you going to run. After that, do you want more crawl out of the truck or more top end. Here is what I did. I had 3.55, 4x4, stock axles, 30" tires. I put on a 6" lift, went to 35's and redid my gears to 4.56. I want crawl, not highway speed since I only really do 100 klicks (~60 mph) tops. I can't afford the speeding tickets. As to what it involves, when I put the lift in, I already had the rear axle dropped so I took the whole think to the shop to get regeared. All you need is new ring, pinion, and a master instal kit, as long as your spider gears are OK. If you are stock, then the rear is an 8.8 and the front is a Dana 44. You can change the gears in the 44 up to 3.73, but if you want to go higher, you will need a new carrier. This is not a big deal. They are only around $60 US. There are alot of places that sell gears, but I bought mine through Randy's ring and pinion and had them shipped here to me. They beat all the prices in Canada, even with the exhange, shipping and broakerage. Now to redo the gears in the 44, it is more difficult since you have to basicly drop the whole thing to get access to the pod, but since I had the whole front apart anyways to put the lift in, I took the pod out and just took the pod into the shop to get regeared.


I played alot with this gear calculator http://www.bncoffroad.com/tire_gear_cal.html until I found what I liked for the gears. I am very happy with the outcome of my truck. If I would have gone any higher (lower number, like 4.10) I would not get the crawl that I wanted.

I hope this helps. Like I said, if you want to put in a lift, then I would regear at that time since you will save a little coin since the axles will be out. Feel free to ask any questions. The guys on this site are great. This is how I got all my info. Just post some pics when you are done

 

Cool! I'm really starting to get the picture.
Basically, All I wanted to do with the truck was to put more power and looks to it. So like you said, I would lift it not more than like 3-4" and put larger tires and wheels on it. To get more power, I imagine I would need bigger gears. Someone had mentionned to me a 3.73 ratio. What do you guys think of that???

I don't want to go nuts with height and offroad stuff. I just want it to look meaner.

Also, What would you guys suggest for new wheels and tire sizes to fit a 4" lift??

By the way, I only have a 2X4 so I don't need to mess with a front axle.

Thank you very much, this is extremely helpful!!!

 

There are alot of different thoughts on what size lift you need for what tires. I have heard of some guys sticking 33's on stock and some 35's with a little trimming (mind you these are 4x4's). 4" and 33's would look good. I like the look of a little more clearance on my truck, that is why I went with 6 for the 35's. I have pics in my gallery of you want to look.

For you, 3.73 will get you out of the hole quicker, if you are looking for more jump, but your rpm's will be higher at higher speed, therefore more gas. If this is what you are looking for, then a 3.73 and 33's would be good. If you want lower rpm on the highway, then go with 3.55's. The calculator will tell you exactly what your rpm will be with a different gear and tire specs and the tranny ratio that you have.

As for tires, what do you intend to use the truck for? Some mild offroad and mostly highway, or gravel road (logging roads) and city or ......? If you can fill in the blanks we can help on a tire selection. Also, if you live ina place that has alot of snow and ice like me, then that is something to consider as well.

Enjoy working on your rig. I love working on mine.