14 bolt GM diff - The 1947 - Present Chevrolet & GMC Truck Message Board Network

aussichev · 08-30-2003, 08:17 AM

Nobody here in Western Australia knows much about this diff.
Is it anything like a dana 60 (bits interchangable)?
Is it a good diff,tough,any problems with it?
It`s 8 stud could I change it to a different pattern if i wanted to?
Where is a good place to look for diffrent ratios?

hrc200x · 08-30-2003, 10:04 AM

The full floater is probably the stongest, but both the semi and full floater have their pros and cons. Of course with a full floater you have to pull the axle out and deal with the nuts inside the hub just to change brakes, but then again if you want to change an axle you don't need to mess with C clips in the diff.

I have yet to see a full floater go bad. I belive I read in a magazine the FF weights around 600 pounds, so moving it around will be no light snap.

Look for FF's in 73- 80 chevy's for sure, if you see a 73-80 2wd or 4wd 3/4 ton or 1 ton chances are it has a 14 bolt full floater. They were sometimes equiped with a Gov-Loc. I'm not really sure how they work, but something like if you get above 15mph the locker won't ever lock so you won't spin out of controll. Some say Gov Locs are weak. The ratios I've heard of in 14 bolt FF axles is 3.73, 4.10, and 4.56. Most 2wd 3/4 tons from the 70s seem to have 3.73 ratio around here, while most 4wd's have 4.10.

Look for semi floaters in 81-87 3/4 ton pickups and suburbans. I don't know if 2wd in these years came with semi's or not, my '84 GMC has a FF. I think there is a kit avialable to change a 14 bolt semi to 5 lug, but I'm not positive.

onetoncrewcab · 08-30-2003, 09:16 PM

I just junked out a 1985 3/4 ton 2 wheel drive Suburban that had a semi float rear axle.
Mike

low 84 · 08-30-2003, 09:46 PM

the early 90s ss454 trucks had 5 lug 14 bolts

i'd like to get ahold of one of those!

aussichev · 08-31-2003, 04:47 AM

Thanks for the replys.I`ve got a full floater (I think) and i did here that they where tuff.The the ratio in it sounds like it might be around the 4.56 my 350 hums at 60miles an hour not what i want so i guess i will have to change it . where would be a good place to look for new ratios.
Paul down under

*gmtrucksaddict* · 08-31-2003, 02:14 PM

takes special toolsand knowledgeot change gears, you will be betteroff finding a better geared rear axle assembly, coloradok5.comis where to ask about changing the 14bolt FF from 8lug to 5or 6lug, i have pics from a member who did that to one

14 bolt FFis 10.5"
14 bolt FF is hard ot find underpickups after 1980
mostly the SF 14 botl was used after then

phantom dually · 08-31-2003, 04:41 PM

I have a 94 with a 14 bolt 9.5" semi floater. It is VERY heavy!! Changed the gear to 4.56

77K20 · 09-01-2003, 02:35 AM

How do you tell the difference between a semi and full floating 14 Bolt? and what is the difference between the two? I have a 77 with a 14 bolt, so I probably have a FF right?

Thanks in adance for any and all info.

2-Knee

hrc200x · 09-01-2003, 11:20 AM

YOu can see the difference in the pumkin, but the easiest way is to take off the hub cap if you have one. If you see 8 bolts where the axle sticks through the rim then its a FF.

Its hard to see in this pic, but if you look at the middle of the rear rim you'll see a small circle, thats the end of the axle with the 8 bolts in it. If you remove those 8 bolts and pull the whole axle will come out.

08-30-2003, 08:17 AM	#1
aussichev Registered User Join Date: Aug 2003 Location: western Australia Posts: 124	14 bolt GM diff Nobody here in Western Australia knows much about this diff. Is it anything like a dana 60 (bits interchangable)? Is it a good diff,tough,any problems with it? It`s 8 stud could I change it to a different pattern if i wanted to? Where is a good place to look for diffrent ratios?

08-30-2003, 10:04 AM	#2
hrc200x Registered User Join Date: Sep 2002 Location: Minnesota Posts: 203	The full floater is probably the stongest, but both the semi and full floater have their pros and cons. Of course with a full floater you have to pull the axle out and deal with the nuts inside the hub just to change brakes, but then again if you want to change an axle you don't need to mess with C clips in the diff. I have yet to see a full floater go bad. I belive I read in a magazine the FF weights around 600 pounds, so moving it around will be no light snap. Look for FF's in 73- 80 chevy's for sure, if you see a 73-80 2wd or 4wd 3/4 ton or 1 ton chances are it has a 14 bolt full floater. They were sometimes equiped with a Gov-Loc. I'm not really sure how they work, but something like if you get above 15mph the locker won't ever lock so you won't spin out of controll. Some say Gov Locs are weak. The ratios I've heard of in 14 bolt FF axles is 3.73, 4.10, and 4.56. Most 2wd 3/4 tons from the 70s seem to have 3.73 ratio around here, while most 4wd's have 4.10. Look for semi floaters in 81-87 3/4 ton pickups and suburbans. I don't know if 2wd in these years came with semi's or not, my '84 GMC has a FF. I think there is a kit avialable to change a 14 bolt semi to 5 lug, but I'm not positive. __________________ '75 Chevy 3/4 4x4, 6" suspension lift, 3" body lift, 3" lifted gas tanks, '83 cab, '88 clip, 35" cooper tires, American Racing Baja rims, 350, 700r4, 208.

08-30-2003, 09:16 PM	#3
onetoncrewcab One of my kids. Cute eh? Join Date: Oct 2001 Location: Mitchell, SD Posts: 1,286	I just junked out a 1985 3/4 ton 2 wheel drive Suburban that had a semi float rear axle. Mike __________________ If a kid asks where rain comes from, I think a cute thing to tell him is “God is crying.” And if he asks why God is crying, another cute thing to tell him is “Probably because of something you did. John 3:16 2006 Chevy HHR 2000 Dodge Durango 1985 Jeep CJ-7 1970 Chevy Pickup

08-30-2003, 09:46 PM	#4
low 84 Registered User Join Date: Jan 2002 Location: Houston, TX Posts: 2,144	the early 90s ss454 trucks had 5 lug 14 bolts i'd like to get ahold of one of those! __________________ '51 F100, backhalf with a narrowed 9 and coil overs, 18.5" mickeys, monte front clip, +400" sbc in the works '05 1500 Crew Cab RIP '84 swb 5/7 drop, solid cammed 408 w/ fully ported dart heads, th350 w/ 10 inch hughes, 12 bolt w/ 3.73 richmonds and a locker '80 swb 4x4 in progress: 7" lift, 350 th350/np205, d44 and 1.5" ORD tie rod, 14BFF w/discs , armored diff covers, 40" MTR's

08-31-2003, 04:41 PM	#7
phantom dually Project92 SWB stepside Join Date: Feb 2003 Location: Louisville KY Posts: 4,792	I have a 94 with a 14 bolt 9.5" semi floater. It is VERY heavy!! Changed the gear to 4.56 __________________ 92 C1500 stepside 496 Stroker Competiton Engineering Ladder bars/QA1 coilovers. Dana 60 rear with 4.10 gear and posi. Bonspeed Palisade 20x12 in rear w/335/30/20 and 20x8.5 front w/245/40/20. 5/8 drop with Belltech springs/DJM spindles/drop shocks. WWS Progress thread http://67-72chevytrucks.com/vboard/s...d.php?t=140448

08-31-2003, 04:47 AM	#5
aussichev Registered User Join Date: Aug 2003 Location: western Australia Posts: 124	Thanks for the replys.I`ve got a full floater (I think) and i did here that they where tuff.The the ratio in it sounds like it might be around the 4.56 my 350 hums at 60miles an hour not what i want so i guess i will have to change it . where would be a good place to look for new ratios. Paul down under

08-31-2003, 02:14 PM	#6
gmtrucksaddict Account Suspended Join Date: Aug 2003 Location: IL Posts: 60	takes special toolsand knowledgeot change gears, you will be betteroff finding a better geared rear axle assembly, coloradok5.comis where to ask about changing the 14bolt FF from 8lug to 5or 6lug, i have pics from a member who did that to one 14 bolt FFis 10.5" 14 bolt FF is hard ot find underpickups after 1980 mostly the SF 14 botl was used after then

09-01-2003, 02:35 AM	#8
77K20 Registered User Join Date: Jun 2003 Location: Estacada, OR Posts: 37	How do you tell the difference between a semi and full floating 14 Bolt? and what is the difference between the two? I have a 77 with a 14 bolt, so I probably have a FF right? Thanks in adance for any and all info. 2-Knee

09-01-2003, 11:20 AM	#9
hrc200x Registered User Join Date: Sep 2002 Location: Minnesota Posts: 203	YOu can see the difference in the pumkin, but the easiest way is to take off the hub cap if you have one. If you see 8 bolts where the axle sticks through the rim then its a FF. Its hard to see in this pic, but if you look at the middle of the rear rim you'll see a small circle, thats the end of the axle with the 8 bolts in it. If you remove those 8 bolts and pull the whole axle will come out. __________________ '75 Chevy 3/4 4x4, 6" suspension lift, 3" body lift, 3" lifted gas tanks, '83 cab, '88 clip, 35" cooper tires, American Racing Baja rims, 350, 700r4, 208.



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