35s in the sand - stock gearing

[prossett]

I've read a lot of posts on 35s and their pros and cons, but I'm still unsure.

So here's a personalized question - I drive a beautiful 1983 Jimmy, manual gears, 305 engine, headers, 2" lift, and I only drive in sand dunes - big big sand dunes.

I think my diff gears are stock, somewhere from 3 to 3.7something, and the axles are GM 10 bolts. I don't do rocks or mud, just sand, so I'm not concerned about them breaking.

My worry, though, is loss of acceleration. Oftentimes I need a good run-up to get up a long dune.

I currently run dedicated sand tires 9.00x15 (33"s) and off the start the acceleration is not brilliant, but good enough.

Based on your experience, would going to 35s worsen performance on sand or improve it?

I'm thinking of buying Yokohama Geolanders 315/75R16 which measure out to 34.5x12.50 (got 16" rims from a Nissan that fit). This is what they look like:

Your comments appreciated.

 

[resurrected_jimmy]

you need to get your gearing figured out, 3.08 or 3.73 is a big difference in gearing..... either way I think you are going to have to run a round in low range most of the time to keep from bogging the engine bown too much with 35's

 

[prossett]

A fair comment. I should know the gearing by now... to tell the truth I stupidly forgot to count when I had the front out!

On climbs I normally run 4-LO 2nd gear.

Here's a pic if anyone can figure out how to count the teeth:

 

[southernspeed]

I use 4.10's with 35's and it's almost stock like.

 

[muddybuddy]

i ran 35s with 3.73's. would do deep mud and never had a "lack of power," but ive got a 350tbi. my guess is that you have 3.08's if ur talking bout having trouble with 33s

 

[big83chevy4x4]

i used to run 35s and 3.42s. in the dunes, i could do anything in high range. could bearly do anything in low. i ran 3.42s for quite a while and never needed deeper gears.
i now run 4.10s and 35s and its great. i havn't been on the dunes with 4.10s yet so i don't know how it is. in the mud though, it doesn't compare.

i say get the 35s, run them and change the gears/axles when you can afford it.

 

[prossett]

Could be 3.08s, I really don't know. Can you tell from the pic? (previous post)

I don't have trouble with 33s, I climb like a gazelle - it's just not fast off the start and changing into second takes forever! Mind you, I don't have any other similar trucks to compare with, only Wranglers...

BigChevy, I normally run in high range on regular dunes (maybe up to 10-12 feet or so) but for a long climb I find low range gives me more. These are kick-a$$ dunes out here, BTW, it's a sand box that runs hundreds of miles non-stop!!

 

[OffRoad]

i'd put in 4.10s or get 3/4 ton axles with 4.10s.

 

[cbbr]

I use 4.10's with 35's and it's almost stock like.

Same here - 35's, 4.10's and a th400. The tranny is a considerationbecause of its gearing also.

 

[muddybuddy]

14b with 4.56 and a detroit and then regear ur front never worry bout having problems in dunes again

 

[prossett]

I live in the middle of the friggin desert where not even FedEx gets to (but they come close). I'm stuck with what gears I've got, but I'm not complaining, just happy I've got a beautiful and absolutely unique 22-yr-old GMC truck to drive!!!

But I also don't want to blow $400 on tires that will slow me down...

 

[muddybuddy]

im sure those tires will be fine. also could look into mickey thompson's. probably more expensive then what ur looking at, but are designed for sand, since u dont do mud or rocks.

 

[dontoe]

305 with big tires and high gears, you'll be disappointed with the take off and acceleration. And pulling any grade will tax it!

 

[tunedportk5]

All I know is I love the freaking sand!!

I think really all that matters is enough HP to keep up the RPM's. I have BF mud terrain 35's with stock gears. and I have a beeft up 700r4 and replaced the carb with the TPI on the stock 350. this combo work really good at pismo dunes

 

[SchnorrCS]

I had an 83 GMC 1/2 ton, and it had 3.73s in it, and I would bet yours does too. GM put 3.73s in everything. Mine also had a 305, and it was a good motor. Lasted forever, but wicked gutless. If it were my truck, I'd put a 350 in or go 4.11 posi in the axles. Either way, with a 305 and 35s, she'll hurt. She'll do it, but she'll hurt.