How can I tell what gear ratio my blazer has. It's a 87 k5 350/700r4 completely stock.
Im new here and from doing a little reading my plan is 4" lift up front ORD shackle flip in the back, fender trimming and 35" tires.
How will the 10 bolts hang with the 35s and what gear ratio should I have for 35s, I'd probably rather save for a 14bolt then do a gear swap in a 10 bolt if so, it would prob be better for me to go with 33s for now?
Ok here's a bit of starter info for you.
Use this link for your current gear ratio.
http://www.73-87.com/chevy_ids/rpomenu2.htm
Your RPO codes should be in your glove box, they may or may not have a description next to them. If not the gear codes should start with a G (IE: GU6, GT4, GU4, etc.)
My opinion, I wouldn't go with any bigger tires than 35's if you plan on any hard core wheeling. If your just gonna be driving and cruising around with your truck you'll be fine.
If you want to do a gear swap, but want 14 bolts, you might as well wait till you get the new axles instead of spending the money twice, unless you have lots of it.
Gear ratio will depend on what your plans are with the truck (IE: trail rig, DD, etc.)
But here is a basic chart to help you decide:
Although you should take the time to do the math and find out which ratio is best for your truck and tire combination, to make things easier we've put together the following chart. This information will give you a general idea what ratios to shop for, but always discuss your gearing needs with a professional at your local shop before buying.
The chart is divided into three categories. The rpm highlighted in black are optimum for the tire size and ratio combination. These will most closely give you the best overall drivability. If you're looking for a ratio that will give better fuel economy for highway driving at the expense of some acceleration and overall performance, choose a ratio in the yellow shaded area. If you're looking for a ratio that will improve acceleration and towing power at the expense of some fuel economy, choose a ratio in the blue shaded area.
Note: This chart is based on engine rpm at 65 mph with the transmission in a 1:1 gear ratio (Third with a three-speed manual, Fourth with a four-speed manual, or Third with an Automatic). Remember, the actual rpm indicated in the chart will be slightly higher (between 100 and 300 rpm) on vehicles equipped with an automatic transmission. This is due to the slip present in an auto transmission's torque converter.
My current setup is as follows: 86 K-5/350/700R/ 4:88's/ 10 bolts
Hopefully this helps
