Well, I think I'm going to bite the bullet and do my gear swap now. I still have the stock gear ratio of 4.10 which I haven't changed since I lifted my truck and put on 35's. The question is, should I go with 4.56 or 4.88 gears? Traditionally, most people match 4.56 gears with 35" tires and use 4.88's with 38" tires. However, in order to restore my factory tire/gear ratio, I would need 4.88 gears. 4.10's on 29" tires is about equivalent to 4.88's on 35" tires. This would correct my speedo, and consequently my odometer, tripometer and would allow my rear abs to work properly once again. There is also another factor that must be taken into consideration-- my transmission gear ratios. Since I have the AOD tranny (which I plan on keeping), my 1st gear ratio is pretty tall at 2.40:1. This is much higher than the E4OD 1st gear ratio which is about 2.87:1 or somewhere around there. Most manuals have a 1st gear ratio of 3+:1. Considering this, I think I need all the help I can get. I also have a high 2nd gear ratio (1.47:1) and a high OD ratio (0.68:1). Above all, I just want to avoid making the same mistake that I made with my engine swap and my lift. I went conservative on them, choosing not to beef up the engine or swap in a 351 and only going with a 4" lift instead of higher and I would hate to spend all this money on a gear swap only to have to do another change in the future. So I guess I'm just want to know if anyone else thinks this is a good idea or if I'm just trying to rationalize the irrational. Thanks.

 

I got 4.10's and 31" tires and wish I had more gear than I got. If I had 35" tires I probably would go with at least 4.88 or maybe even a little considering the aod tranny which I have also.

 

i am running 4.56's with 36's. it is pretty much right on the money with stock drive. as you know with bigger tires they are heavier and it drags you down a little. so if you do alot of highway you may want to go higher so your not kicking down very much, that is if your running a basically stock motor. good luck !

 

so am i crazy for not being out under my truck right now putting in the new gear set i have waiting? It sounds like im missing out on alot of power running 3.55s and 33" tires.

 

I don't think it's worth changing with only 33" tires. When I put mine on, I only noticed a power loss out on the highway, which was quite substantial, but I still don't have any problem running 70-75mph as long as there is not a heavy headwind. With 3.55 gearing and 33" tires, I turn 2000rpm @ 60mph in overdrive (5 speed manual). That is verified with a GPS since my speedo is so far off I don't ever pay attention to it anyway. With an auto, the engine will be lugging a bit more though.

 

In my opinion- If you have an overdrive tranny you cant have too much gear. Go for the 4.88's.

 

With a 302 an automatic and standard 29' tires, the smallest gear ratio that makes any sense to me from a performance, hauling, towing or general truck use standpoint is 3.55. Anything less is for highway fuel economy only. To get the 302 into it's best working range, the 4.10s actually make more sense. Going to 35s to be equal to that you'd need 4.30s. 4.56 would be about equal to 3.73 with the standard tires and as you said the 4.88s would be about equal to 4.10s.

If you can take the highway fuel economy hit (and its not that big a hit) go with the 4.88s. You'll gain performance, towing, hauling and off-road capability and will either gain a hair or hold even in around town fuel economy.

 

Thanks for the replies guys! I decided that I will get the 4.88's. I had some doubts after telling some of my friends (one of my friends is running 4.88's with 42" tires!!!). So they thought I was kind of crazy at first for wanting to go that low, but after I reminded to them that I have an auto tranny with OD and high gear ratios, the 4.10's came stock on 29" tires, and I'm building my rig for on/off road performance and not for putting around, I guess they understood. I did, however, decide to hold off until next summer. Basically, for two reasons: 1) I'll be doing freeway driving 7 days a week from now until next summer and 2) I'd rather save up and pay cash than use credit and this way I can justify the large expense as a college graduation present to myself next June Any ways, thanks again for the advice!

 

4.88