Anyone have 4.88 and 35s?

[The Loner]

Currently running 33s with 3.73. I am going to move up to 35s and regearing. It has the 305 and auto w/ od. The setup is terrible in my opinion. It pulls grades like a semi, takes a lot of throttle to get over rocks, and offroad goes downhill way too fast. Dont have enough cash for atlas or 350. I was thinking 4.88 might be a good alternative since I am regearing anyway? What I am worried about is engine, tranny, or axle damage from them spinning too fast on the freeway. It is a daily driver. Should I go 4.56 or 4.88? I think the guys at the local 4x4 place use meth, so they're not much help.

My other question is about axles. Can't decide if I should stay half ton w/ detroit and moser in back, or switch to 3/4 ton. I know the 14 bolt detroit is cheap, but the ring and pinion is more. I was thinking it would be best to keep weight down with the small motor. Opinions? Thanks for any thoughts.--B

 

[mudhog]

with the overdrive i think you would be ok with 4:88's /forums/images/icons/smile.gif

 

[m j]

it is simple to plug the numbers into a gear calculator but you have to decide what rpm you are comfortable running at.
old school guys dont mind 2500-3500rpm cruise speed but new stuff with OD runs much lower then that for fuel economy

 

[MR.4x4]

I have 35 and 3.40 (12/41) and in off-road is great!!!

I dont do x-treme Rock-Crawling but i dont need more power, i have 350 and with the 4L it Rocks!!!

Today im buying some lockers!!

 

[The Loner]

I guess we have a difference of opinion about gearing then! I played with the gear calculators and I think 4.88 is the way I want to go. I'm just wondering if the rear 10 bolt w/ 4.88s is going to hold up?

 

[MR.4x4]

Sorry, i have 12 Blt in the rear!!

Again, i dont make hard Rock-crawling.

But if you can afford the new gears go get them /forums/images/icons/cool.gif

 

[TopOff]

THe only problem I foresee is the small pinion gear. I think that will be your week link.

overdrive should be at .75 x 4.88 assuming you have some BFGs 35" which are really 34.5" you should be pulling ~2300 rpms at 65 mph.
If they are trully 35" then ~2280 rpms

 

[MaxCrack]

I have 4.88's with 37" tires. It does really well on the freeway. Of course, my tach is not working so I don't know how fast the engine is running, but it sounds good. The temp gauge is working and the motor temp is fine. Even after doing about 70 for 2 hours. It does OK crawling. If I go bigger tires I will definatly have to go lower gears.

As for 3/4 ton with a 305, I do not have any experience. But when I went to Dana70's I did not notice the engine working any harder, of course I also went from 35" tires and 3.07 gears to 37" tires and 4.88 gears at the same time.

 

[Blazinaire]

I have a 350/700 combo with a 10/12 bolt with 4.56's and 35''s. IMHO this is more than enough gear, when I let off of the gas in low range the truck skids, and it bounces off the rev limiter at 8 1/2 mph in low range first gear. I do know one person with 4.88's and 35''s but he has D60/14ff in his jimmy. I have two concerns: 1: the pinion gear for a 10 bolt with 4.56's is smaller than I am really comfortable with and the pinion only gets smaller the deeper you go. 2: while the engine RPM may be acceptable to you, you must remember that because of the OD in the 700 the driveshaft will be spinning 30% faster. If your truck is lifted (I'm assuming it is if you are running 35''s) the u-joint angles are probably out of whack and the higher speed of the shaft with 4.88's will cause some pretty mean vibrations. But if you do decide to go that route, a c/v shaft should take care of that problem. I think that 4.88's with 35''s is great if you don't have to do a lot of highway driving otherwise I would say to go with 4.56 (or dare I say 4.10) As for detroit and moser vs. 3/4 ton, my $.02: go 3/4 ton now so you can already have 8 lug wheels for down the road (D60!) not to mention the indestructable 14bolt!