14 bolt swap questions
 

I have a HO52 in my 69' Suburban. I want better gear options so I'm looking to swap in a 14 bolt. I have coil spring suspension. What do I look for when locating a 14 bolt? I plan on having it gone thru before installing it. I'd like a direct bolt in if possible. If not how close to direct bolt in can I get? Specifics would be great. Can I use leaf spring axle. Will the e break cables direct connect etc. Thanks

Re: 14 bolt swap questions
 

There will be modification.

There will be no direct bolt in 14Bolts. Leaf spring perches will need to be cut off and coil spring perches welded on.

Cable is cable, so one way or another the 14Bolt e-brake cables can be connected.

Re: 14 bolt swap questions
 

Are there any specific years of Doner trucks that are better than others? I'm looking for 3.54 or 3.73 gears, correct shock mounts etc.

Re: 14 bolt swap questions
 

There will be no correct shock mounts either.

You can get 14 bolt full floating axles out of HD 3/4 ton trucks and 1 ton trucks. These are some of the best axles the General ever put under a truck. They are all 8 lug and have a huge 10.5" ring gear. The started sometime around 1977 and stopped using them in the mid late 80's. There are semi floating options for this axle as well. Most of those found their way under 3/4 ton suburbans. These 2 forms of the 14 bolt are bomb proof.

There are also smaller versions of the 14 bolt with 9.5" ring gears that are semi floaters that came under late 80's to late 90's half tons and some 3/4 tons. They are a 6 lug and can be forund in most wrecking yards for a decent price.

But just remember, like ERASER5 said. NONE of them will be a direct bolt in for the 67-72 trucks.

Gary

Re: 14 bolt swap questions
 

Don't mean to hijack the thread but....
Do leaf spring perches of LATE 70s 14 bolt match with our trucks if they were equipped with leaf???
Do any of them come in 4.56 gear?

Re: 14 bolt swap questions
 

This kind of leads into my next question. Should I ditch the coil springs in favor of leafs? I can't see much difference in the amount of work needed to do either job. Sorry but I don't understand what "Semi Floating" and "Full Floating" means. My purpose for doing this is to gain a little fuel mileage while reducing RPM at freeway speeds. At some point (not too distant future) I will be replacing the turbo 400 for a 700R. The 4.56's in the HO52 are killing me!! I don't tow heavy but I do tow a small 3500# travel trailer or a 16" flatbed with my Jeep on it. What gear ratio would be suggested? I hope no one is offended by all the questions. I just dont want to get it wrong the first time :dohh:
I'm no stranger to swapping axles and I do weld. I replaced the rear Dana 35c in my jeep to a Ford 8.8. Had to relocate perches and shock mounts and set driveline angle. Did a full axle over lift on it at the same time so the front axle had to get new perches and shock mounts as well.

Re: 14 bolt swap questions
 

Full floating means the driven axles shafts actually "float" in the axle tubes as they bear none of the weight of the load. The axle tubes and housing bear all the load weight. The axle shafts can actually pulled from the vehicle without opening up the diff.

Semi-floating means that the driven axle bears some of the weight of the load.

All of the 14 bolts will be out of leaf sprung trucks. You can convert the 14 bolt over to accept your coil springs. Just need new perches and shock mounts. The e-brake cables will have to be changed to the same year vehicle as the donor axle.

A late model 6 lug 9.5" ring gear 14 bolt out of a mid 90's Chevy/GMC truck would be a perfect swap. I towed a 5,000 pound travel trailer with a 1994 GMC 1/2 ton that had a 9.5" 14 bolt in it. Truck had 4.11's in it. Worked great

Gary

Re: 14 bolt swap questions
 

Thanks for the info Gasoline71. I really want to stay with the 8 lug axle. I like the wheels on the Suburban so I don't want to buy new ones which brings me to a new question. Will the 8 lug bolt pattern on the 14 bolt be the same as the HO52?

Re: 14 bolt swap questions
 

Wasn't even thinking about the 8 luggers on your rig now.

Then a large ring 14 bolt would be the better option.

I also had one of those in a '79 K25 GMC I had. 14 bolt full floating axle. I pulled a lot of heavy stuff with that truck. Again, 4.11's from the factory. =) Great axle.

Gary

Re: 14 bolt swap questions
 

Yes the 8 lug 14 bolts have the same 8 x 6.5" wheel stud pattern as the Eaton HO52/72's

I do make trailing arm mounts specifically for installing the 14 bolt under the '60-'72 trucks.

Re: 14 bolt swap questions
 

And there ya go! Even prefabbed mounts for the 14 bolt!

Gary

Re: 14 bolt swap questions
 

Now I just need to find a good clean one locally! Thanks for the help all!

Re: 14 bolt swap questions
 

Ditto that! You asked all my questions, now I know what to be looking for too and I will hit up captain fab about his mounts

Re: 14 bolt swap questions
 

If captainfab does not work out for you, there is a complete kit available from Classicparts.com
http://www.classicparts.com/Trk4Flip/index.html#120

Re: 14 bolt swap questions
 

Randy's gear and rpm calculator says for 4.56 gears, 31" tires and 65 mph, the RPM's would be

3 speed auto trans (1-1 Final Drive Ratio).= 3299 RPM
4 speed OD auto (.70 FDR).....................= 2249 RPM
4 speed man........................................= 3213 RPM
5 speed man. (.80 FDR).........................= 2570 RPM

Change the Gear ratio to 3.73 and you get

3 speed auto.........................................= 2698 RPM
4 speed OD auto....................................= 1839 RPM
4 speed man.........................................= 2628 RPM
5 speed man.........................................= 2102 RPM

Going from 4.56 to 3.73 is a fairly substantial reduction in RPM. Should net about 20% increase in MPG. So 9 mpg now would result in almost 2 mpg increase.

Re: 14 bolt swap questions
 

Full floating means the axle shaft only drives the wheel and doesn't support the weight. It uses two wheel bearings on a hub like a front setup on a 4x4. You can spot these when the wheel centers are off by the protruding hub with 6 bolts in it.

The full float 14 came out in 1973 in GM trucks. The Semi-Float (meaning axles drive the wheel and support the weight, single wheel bearing in the housing like a car) came out in 1981. They are flat on the end except for where it chucks in the machine tools so no protrusion on the hub.

I would look for a 4.10 center section and run as tall a tire as possible in the near term as you budget for the OD trans. The 4.10 will be a better gear all around with the OD.

Re: 14 bolt swap questions
 

4.1 gears with 31" tires should put you in the power band for best overall performance

65 MPH @ 1:1 = 2890 RPM
65 MPH @ 0.7:1 = 2023 RPM

Re: 14 bolt swap questions
 

If I am gonna keep the th400, would 3.73 be better gearing in the 14 bolt?

Re: 14 bolt swap questions
 

Your transmission is not involved in the decision, other than your top gear ratio, which will be 1:1 regardless of your rear gear ratio.

The decision you should make regarding rear gearing is between your tire size, RPM and speed. See here: http://www.coastdriveline.com/htmlfo...lculator2.html

Re: 14 bolt swap questions
 

Unless you have an overdrive trans like a 700R4 (.070:1) or NV4500 (.073:1).

Re: 14 bolt swap questions
 

Will this work and is that a reasonable price? What should a 73 to 80 axle cost?
"Selling complete take out rearend from 2001 2500HD silverado. Disc brakes. 100% complete. $500 OBO."

Re: 14 bolt swap questions
 

Just got done with a 14B swap in my 71 K20. From what I've heard, unless you get one from a 1 ton truck, the spring perches have to be moved. The 14B I got came from a 79 K20

Here's what had to be done on mine:

-Move spring perches
-Move shock mounts
-Change to 3/16 brake line
-E brake cables too short. Still unhooked (have automatic, so no big deal)
-Change to strap-style ujoint retainers

Think that was about it. Had to replace my roasted HO52 after the spiders tried to weld themselves to the carrier!

Re: 14 bolt swap questions
 

Those trailing arm mounts are for 3" axle tubes. The 14 bolts have 3-3/8" axle tubes.

Re: 14 bolt swap questions
 

FWIW , 9.5" SF rears are 8 lug at least 50% of the time - if not more , but ratios are normally either 3.73 or 4.10. Brake sizes and axle widths vary among both 14 bolts also. Please do your homework !

Re: 14 bolt swap questions
 

. I am installing a semi float 14 bolt in a 69 C20,coil spring truck. The 14 bolt has an axel tube diameter of 3 -5/16”. I need the weld on trailing arm mounts & U bolts.What do you have?