What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

What gears to get? PLZ HELP!

P

PorterzCustomz

Registered Member
Joined
Apr 19, 2007
Posts
28
Reaction score
0
Location
CT
I have a 1990 K5 Blazer. I just put on 35's and the power was effected greatly and I want to restore the gearing to compensate for them. I bought the truck with 33's and the gearing was decent, Is there a way to calculate the difference? The 33's were A/T and my 35's are mud tires so they are more like 36's if they were A/T because of the tread.

I want to replace the gears so they compensate for the tires. I wouldent mind restoring it to stock gearing or even how it was geared with the 33 A/T. What is stock ratio and what size would I need to replace it with? :confused:

Thanks!!
Eric
 
4.56's if you have an overdrive tranny. 4.10 if not.

Tread pattern has nothing to do with tire height.
 
not pattern but road tires and offroad mud tires have different tread height
 
Would that be bringing it back to stock gearing or is that what it would be with the 33's?

I know its not exact, Would that be the low side or the high side compaird to stock?

What is the stock gearing?
 
Do you plan on larger then the 35" tires you have now? If yes then 5.13's or 4.88's if you have the OD gear. If no larger then 35's with OD then 4.88's or 4.56's.

If no OD and you see highway then 4.10's.

I had 35" tires with 4.56's and OD and wish I had went to 4.88's or 5.13's especially since I now have 37" tires.

Harley
 
Go with 4.88 gears. In overdrive at 75 you'll be turning 3200 rpm's--this ratio also works best with the NP 208 t-case in 4 low. 4.56 gears with a 700R4 tranny is too high. If you have this tranny and don't use it on the highway very much I'd even go with 5.13's. Call ORD--this is what they recommended for me and I've been thrilled with it.
 
Where is the cheapest place to buy your gears???

Hunterguy, why did u go with a 14 bolt rear and leave the 10 bolt front?? Is it really nessisary to go 14 bolt rear? If so why leave the front??
 
PorterzCustomz said:
Where is the cheapest place to buy your gears???

Hunterguy, why did u go with a 14 bolt rear and leave the 10 bolt front?? Is it really nessisary to go 14 bolt rear? If so why leave the front??
Click to expand...

I broke the rear 10 bolt so I went 14 cause its stronger. I left the front 10 bolt cause it will hold up under the tires i'm running and for the wheeling I do.
 
Ohh, What were you running that broke the 10 bolt?? I herd with lockers it makes it stronger is that correct?? What does it take to brake the stock rear??

Where is the cheapest place to buy gears!?
 
PorterzCustomz said:
Ohh, What were you running that broke the 10 bolt?? I herd with lockers it makes it stronger is that correct?? What does it take to brake the stock rear??
Click to expand...
Mainly bad luck. It's a poor design but some people can wheel the snot out of them on 35's and not break a thing. Then there's the mud guys with 44's on 3.08 geared 10 bolts who claim to have never broken anything...:rolleyes:

I know two people who have broken the supposedly stronger 30-spline 10 bolts from 90's trucks. One truck had stock sized tires and the other had narrow 33's. There's lots of similar stories.

Spending money on a 10 bolts is a risky thing. You might be fine or you might be polishing a big, expensive turd.
 
PorterzCustomz said:
I herd lockers make the rear ends stronger somehow??
Click to expand...
If you install a full carrier locker (detroit, ARB, etc), then yes, those carriers are stronger than the stock carrier. The shafts are the same though, and a locker puts MUCH more stress on the shafts.

You will have much more problem with breakage on a 1/2 ton axle with a locker than you will without.

Seriously, buy a membership here and check out the numerous other threads on this subject. Its well worth your money.
 
I run a '91 with 700r4 and 35 BFG/MT. 4.10s are almost stock like. At an indicated 70mph I'm doing 65 mph so that's about as close to stock as you'll get. If you want a little bit more grunt, go for 4.56s.
 
I had really never seen a 10 bolt brake except a few times when the spider gears exploded because of excessive wheel speed in a stuck. That was until a month ago and 2 of them went within a week one the cross pin bolt came loose and slid out hooking on the case and the other the govloc exploded. The bolt problem can happen with a 12 bolt as well so it is not just the 10. I have a limited and locked 84 k-10 on 33s and since I bought it this way I am upgrading the rear axles but I recommend doing a 3/4 or 1 ton swap to get stronger axles and better gears. My buddy just bought a 78 3/4 gmc with a newer goodwrench motor/th400/203s and 44/14 with 4.56s for $300 runs great lost of rust large cab dent. To regear my axles was about $2500 with parts and labor.
 
you need to know your original gear. 4.56 won't make much difference if you are 4.10 now. I would suggest 4.56 gear unless you had 4.10 to start. If you have 4.10 to start, I would suggest 4.88
 
You must log in or register to reply here.

Latest Posts

Top Bottom