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Discussion Starter · #1 ·
I have a 1979 GMC K10 shortbed and in the near future will be looking to change the gearing to something around a 3.73 or maybe a 4.11 ratio. What I would like to know is if the ring and pinion parts are the same for the front and rear? It would make sense that they would be the same part numbers, but I have not dealt with them to know. So, are they the same or are they different parts?
 

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Num 1 Dad, I am no expert but I believe GM vehicles used a smaller front ratio than the rear. Seems like it was something like 3.07 front 3.08 rear. Others will chime in.
 

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I googled Napa site and there is a difference from the front and rear. However its the ring size 8.50 front 8.60. Most GM vehicles use Dana differentials. I once changed a 1975 Chevy Camaro gear ratio from 3.08 to 3.73.That really spruced up the cars performance and was a good all around gear choice. It had plenty of low end and top end performance. I had it installed and had purchased an after market set. The problem was an annoying whine that never could be removed. I had two different mechanics try to shim, or adjust it, the whine remained. I would use factory parts if available. My problem could have been a one in a hundred situation. Don't forget to replace the speedometer gear set also. Got a speeding ticket like that once. Other's will answer with better imfo. and may question tire size you plan to run and may even advice a lower gear.
 

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In most trucks the front and rear diff's are different, due to the sixe of the axles, so they would have different part numbers
Most Gm trucks in your yr would have same gear ratio's front and back, but again, they would be different part numbers
as the rear ends , front/back would be different
 

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Most front ends are .01 faster ie 4.10 front 4.11 rear. However you MUST get the reverse cut to allow for the fact that its turnin backwards basically, unless yer transfer already reverses it. That's somethin else you've got to look into.
 

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You need to make absolutely CERTAIN what axles you have!, your front is most likely a GM Corporate 10 Bolt, But it could be a DANA 44!, the rear could be a GM Corporate 10 Bolt but it may very likely be a GM Corporate 12 bolt.
NO! GM truck ever had a reverse rotation solid front axle, they do INDEED! use the same gear cut in the front and rear!
I wouldn't even consider spending my $$$$$ on OE gears??, there are competitively priced aftermarket gears that are just fine, YUKON is a good one, we sell a TON of them at work, US Gear are ok too.
Be aware there are "Carrier Breaks" too, the Dana 44 is 3.73/3.92, the 10 Bolt is 2.56/2.73 (shouldn't be an issue?, you should already have the low one) and the 12 bolt is 2.73/2.76-3.42/3.73, so you may need one or two new carriers too??
 

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Well said, I can't really add anything I am a mechanic and was at one time ASE master certified with an L-1 cert and a Ford powertrain master. Work in a defense related field now so I let them all expire.
 

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Num 1 Dad, I am no expert but I believe GM vehicles used a smaller front ratio than the rear. Seems like it was something like 3.07 front 3.08 rear. Others will chime in.
I doubt the front and rear would be slightly off.... binding would occur which would result in something breaking. My 74 K10 has matching 3:73's front and rear. It will also depend on which differential that is in the front. It's more than likely a corporate 10 bolt, but it could be a Dana 44.... whenever I'ved looked at ring and pinion sets, the front and rear are listed under different part numbers if I remember correctly.

Also bear in mind that you might have to changes carriers depending on what the current gears are and what you wish to upgrade to.
 

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Discussion Starter · #10 ·
Different ring/pinion part numbers for the front/rear...gotcha

Whine? Not worried :) Won't hear the whine over the noise of the exhaust or tires! :) :)

Possible carrier switch...hmm, may limit what I what as I am working with a budget...might have to go no higher than what, a 3.73? Would like to maybe have the 4.11 or 4.56 as to start with I am going to run 40's on it.

The front is a 10 bolt, have not investigated any further as to the manufacture...and the rear is a 12 bolt...I, at this time, do not know the gearing in it, but I know it is NOT what I want...I am thinking in the 2'ish range, maybe low 3's...and what might be the easiest way to distinguish if the front is indeed a Dana 44? Would pictures help (front and rear)

Thanks all for the input :)
 

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Discussion Starter · #11 ·
OK, found this picture of a Dana 44 and GM 10 Bolt 8.5...does it accurately identify the difference? Just a rounded off bottom vs. squared off?
Just Chevy Trucks.com
 

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Before you dig into this yourself....
Doing a ring and pinion is a SERIOUS job... It's not a job even for the "Average" professional Garage mechanic....
It's not just an unscrew/reinstall job....
It takes about $1,000 worth of specialty tools and measuring equipment (On the low end) beyond the "Usual" wrenches, prybars, etc....

Ring and pinions have to be precision re-aligned and shimmed for exactly the right gear mesh pattern....
Your accuracy has to be somewhere within 0.002"....
You also have to get the bearings shimmed for exactly the right pre-load

Those bearings are pressed on.... so you have to be able to press them back off as well..

What you will find if you take it to a "Good" shop that does stuff like this regularly.....
There's typically ONE guy who does gear/axle work like this...
There's a good reason for this... It takes a LOT of practice to be able to get them in and out efficiently, and to get them all set up properly the first time....

This is the difference between a gear set that lasts 1 year and a gear set that lasts the life of your vehicle...

Thanks
 

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Discussion Starter · #14 ·
I fully understand this as I have read both in the past and recently on the changeing out of the ring/pinion. Tis nothing to snuff at for sure, and do have plans to have it professionally done, which is why my budget is lower than what I would like for this...otherwise, I would be buying me a nice set of lockers for the front and rear ;)

I am just trying to figure out what I need to buy on my own, then take it all at once to have it installed.

And thank you for the concern :)


And also, it looks as though the front is a GM Corporate 10 Bolt as it resembles the left side axle in the picture I posted.
Before you dig into this yourself....
Doing a ring and pinion is a SERIOUS job... It's not a job even for the "Average" professional Garage mechanic....
It's not just an unscrew/reinstall job....
It takes about $1,000 worth of specialty tools and measuring equipment (On the low end) beyond the "Usual" wrenches, prybars, etc....

Ring and pinions have to be precision re-aligned and shimmed for exactly the right gear mesh pattern....
Your accuracy has to be somewhere within 0.002"....
You also have to get the bearings shimmed for exactly the right pre-load

Those bearings are pressed on.... so you have to be able to press them back off as well..

What you will find if you take it to a "Good" shop that does stuff like this regularly.....
There's typically ONE guy who does gear/axle work like this...
There's a good reason for this... It takes a LOT of practice to be able to get them in and out efficiently, and to get them all set up properly the first time....

This is the difference between a gear set that lasts 1 year and a gear set that lasts the life of your vehicle...

Thanks
 

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Discussion Starter · #15 ·
This is getting fun! *sigh*

If I am reading this correctly, I can run a 4:56 in the rear without changing carriers (this is from the Richmond Gear catalog) as it shows part #69-0206-1 will fit the #4 carrier while part #69-0352-1 fits the #3 carrier, so I just have to figure out which one I have before buying the parts....Next will be figuring out what part # I will need for the front...and it looks like I will need a minimum 4.56 to run the 40's....everywhere I read suggest 4.56's for 35's, so the 4.56 would be ok as I may run 35's on it as well.
 

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Call up Randy's ring and pinion and go through it with them.....

At the minimum... You will get the Gears + install kit for both axles.... The install kit may or may not come with bearings... You WANT new bearings all the way around....

If you are going up to 4:56 - you will likely need a new carrier in front.... Go with a locker.

Here's the thing....
The Labor in the shop is your major cost..... You have like $150-200 in parts per axle... The whole job is usually around $800/axle - because of the labor involved....

IF you are going to do lockers - you will have to do the WHOLE thing all over again when you do lockers.... Sure - you will be able to keep the Gears - but you will be redoing all the Labor, bearings, and shims.....

So... Go ahead and do the lockers while you are at it....

I personally went with Detroit lockers front and rear... You hear lots of folks wringing their hands about having a Detroit up front......
Unless you are going to be driving in the Snow/Ice in 4x - you will LOVE it..... Offroad - it's fine... You can turn just fine....

If you plan on Daily Driver use driving on ice/snow.... Leave your axles with Open differentials..... There's nothing like the fun of spinning round and round and round end for end on an icy road.....

So.. Here's why I went with a Detroit.....
Their reliability is LEGENDARY!
And.. Nothing sticks out of the pumpkin to hang/get pulled off on the trail....
All the Air/Electric lockers have ONE common problem.... Air/Electrical lines you gotta route hither and yon through the vehicle.... Hang a branch on your air/electrical line and guess what... No locker... It's more stuff that has to work right.... You gotta keep that electrical connection or Air pump working right or you have NO locker....

Oh.. That will never happen to ME.... Well.. Just last weekend - I hung a branch that pulled my O2 sensor wiring loose from the Exhaust manifold..... That's WAY up in there.... I have had to Chainsaw plenty of big branches out of my drivetrain, suspension, and engine compartment.... It happens....

Thanks
 

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on those two pictures, it seem the bolt pattern is different too?
some times its worth paying to have it done right too, I agree, doing a rear isn't a simple drop in deal, and being off a little can lead to doing it twice, and doubling the costs real quick
on a side note, I also believe the actual PART/maker of the new gear set matters too, cheap made parts don't last and GOOD parts can cost a little more, but save you doing it a second time in the near future
here are a few sites to check out maybe

Randy's Ring & Pinion

Precision Gear Ring and Pinion Gear Sets

Gears, Install Kits, Carriers, Ring & Pinion Gear Sets, Spider Gears, Lockers

Welcome to Richmond Gear - Richmond Gear

http://www.quad4x4.com/#Chevy
 

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Discussion Starter · #18 ·
I personally went with Detroit lockers front and rear... You hear lots of folks wringing their hands about having a Detroit up front......
Unless you are going to be driving in the Snow/Ice in 4x - you will LOVE it..... Offroad - it's fine... You can turn just fine....

If you plan on Daily Driver use driving on ice/snow.... Leave your axles with Open differentials..... There's nothing like the fun of spinning round and round and round end for end on an icy road.....
I have heard excellent things about the Detroit Lockers....rock solid...just noisy when engaging/disengaging. I do plan on it being a for-the-most-part daily driver with some winter off-road fun. I would actually like to have a limited slip front and rear. And I found out all to well what lockers do on snow...my 78 K5 has 44" Interco TSL Super Swampers with 4.56 locked front/rear diffs...in 2 wheel drive, I hit the road with 2" of snow on it and was immediately sideways as soon as I touched the gas...can't believe that I have to run in 4 wheel drive to go on 2" snow...

TSL_Super_Swampers.jpg 78 K5.jpeg

This is what I am working on:

79 K10.jpeg
 

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I fully understand this as I have read both in the past and recently on the changeing out of the ring/pinion. Tis nothing to snuff at for sure, and do have plans to have it professionally done, which is why my budget is lower than what I would like for this...otherwise, I would be buying me a nice set of lockers for the front and rear ;)

I am just trying to figure out what I need to buy on my own, then take it all at once to have it installed.

And thank you for the concern :)


And also, it looks as though the front is a GM Corporate 10 Bolt as it resembles the left side axle in the picture I posted.

Srength wise, a Dana 44 and a Corporate 10 bolt are the same.... it's the axles and joints that need the upgrade for bigger tires
 
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