Gears?

[72 Blaze]

Ok I'm back with another question. I just had my Blazer worked on. As most of you know from pre-post I was having some carb problems... Anyway the Blaze runs great and I just installed two new super 44's sounds great.. to me at least. The guy that works on a couple of my old 4x4s told me it would really help the power of my Blazer to re-gear it. I kinda already knew that. But, I need to know what gears I should run. Its a 72 with stock gears. 350 with mild cam and a 350 trans with shift kit.. Thats my problem I think. I dont have the money for another trans and I dont want to go too low with the gears. 12 bolt out back and a D44 up front. I had a guy quote me new gears and a detroit locker for the rear... 2600.00 seemed high so I backed out... I'm running 35's and do alot of street driving. Also will I be able to feel the Detroit?

Thanks

 

[owenst7]

Ok I'm back with another question. I just had my Blazer worked on. As most of you know from pre-post I was having some carb problems... Anyway the Blaze runs great and I just installed two new super 44's sounds great.. to me at least. The guy that works on a couple of my old 4x4s told me it would really help the power of my Blazer to re-gear it. I kinda already knew that. But, I need to know what gears I should run. Its a 72 with stock gears. 350 with mild cam and a 350 trans with shift kit.. Thats my problem I think. I dont have the money for another trans and I dont want to go too low with the gears. 12 bolt out back and a D44 up front. I had a guy quote me new gears and a detroit locker for the rear... 2600.00 seemed high so I backed out... I'm running 35's and do alot of street driving. Also will I be able to feel the Detroit?

Thanks

$2600 put into half tons is just retarded...it's also pretty high. Find a good deal on the gears and find someone local that knows how to do them. I've helped out friends for dinner and beer.

Would help if you told us what ring/pinion is in there now. However, I was running 3.73s and 35"s in my trail rig for a while and I wasn't too concerned, and that was rock crawling with a stock motor from '76.
http://www.grimmjeeper.com/gears.html

 

[72 Blaze]

Ok I will show how dumb I am.. I dont know what gears she running now i have never cracked opened the diffs. I'm sure what ever came stock back in 1972.. Thats what i wanted to do after I found out what gears Yall thought I should run. I was going to shop around for some and then find a buddy to help me install them...

Thanks again for the replies!

 

[doubletrouble]

I have a '77 blazer with half tons , auto tranny , 3.73 gears and 35 inch tires. Not bad on the street or trail. It will do 80 easy on the highway. I do plan on going lower. I'm thinking maybe 4.33's or 4.56's at most.

 

[1BEATK5]

3.73 or 4.10 would be my suggestion with 35s. i have had 4.10s w/35s a couple times, and i liked it alot for overall performance. the only issue is driving 70+mph. then you are 3000 rpm.

the easiest and cheapest would be some 3/4 ton axles. 3.73 or 4.10s are the most common, add strength, and a detroit for a 14bolt is cheaper.
the 14 bolt wont be a "bolt in" in a 72', but its not too hard either.

 

[Hogback Fabrication]

First, find out what you have. If the tags are missing on your axles (the tag would be around one of the diff cover bolts) then pull the cover on one axle and look for the number stamped into the ring gear. Towards the end of the jumble of numbers will be a couple that tell you the number of ring and pinion teeth (i.e. 41 10 means 41 ring gear teeth and 10 pinion teeth hence a 4.10 gear ratio). If you can't find those numbers you can count the teeth on the ring and pinion.

As for desirable gears, you may have 3.73's and if you do it may not be worth to switch to 4.10's because it isn't a huge difference (the really high ratios, 3.42, 3.08, 2.72 etc didn't come until much later).

IMO 3.73's or 4.10 are what you want; 3.73 being a bit more highway oriented and 4.10 being a bit more performance oriented.

As for new gears, bearings, seals, install and locker that price is high. Give us a call if you're looking for that stuff, we can set you up.

 

[72blazerguy]

As for desirable gears, you may have 3.73's and if you do it may not be worth to switch to 4.10's because it isn't a huge difference (the really high ratios, 3.42, 3.08, 2.72 etc didn't come until much later).

As for new gears, bearings, seals, install and locker that price is high. Give us a call if you're looking for that stuff, we can set you up.

I swapped a set of 3.08 gears out of a 71.

Better figure out what gears you have before deciding what you want to buy. 4.56 will be to low for interstate type driving (ask me how I know) with the tranny setup and you will definitely feel the Detroit. You can adapt your driving, but you will know its there.

From Randy's Ring & Pinion
r&p (yukon) 225
master overhaul kit 135
detroit 642

Looks like about $1,000 for parts (rear only). FWIW, I got a quote to setup new gears for a 14 bolt (been awhile) and the labor was 500.

 

[72 Blaze]

I just got home from an out of town trip.. I ran up to the garage and couldnt find a tag on the rear diff. But I did find a tag on the front.. attached to one of the diff cover bolts. It looks to read 4314 and 307.. Does that
make any sense to anyone?

Thanks

 

[frankin5]

divide 43 by14=3.07

 

[72 Blaze]

Wow thats crazy so I have 3.07 gears in my Blazer... So by going to 3.73 or 4.10 would be a great help. And I have had the Blazer in 4WD for sure, so the rear gears have to be 3.07 too. Im I on the right track here guys? I guess the sure way to really tell is pull the cover off the rear. But for now I think I'm safe to say it has 3.07!

 

[owenst7]

Wow thats crazy so I have 3.07 gears in my Blazer... So by going to 3.73 or 4.10 would be a great help. And I have had the Blazer in 4WD for sure, so the rear gears have to be 3.07 too. Im I on the right track here guys? I guess the sure way to really tell is pull the cover off the rear. But for now I think I'm safe to say it has 3.07!

You can also rotate the tire and count the rotations of the driveshaft.

Play around with a gear ratio calculator online. They are helpful for deciding what you want to accomplish with a ratio change and your driving characteristics.