4wd Trouble
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Joined: Oct 2003
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From: Princeton kentucky
4wd Trouble
I recently bought a 79' f-150. Here is my problem. When locked into 4wd on pavement the front tires chirp, if it is on gravel the do the same only you here the gravel moving as the front tires sort of chuck. Haven't had it in the mud so I don't know how it acts there. Had a friend tell me it sounds like the gears have ben changed in the front or rear end, and know they don't match, cause only one has been changed. It doesn't make any unusual noises when locked in. Any input would be greatly appreciated. Thanks.
Posting Legend
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It is normal to get some movement because the front driveline is set up to go a little faster than the rear to keep the truck straight. Check the ratio's out fore and aft to make sure. Do not engage the 4WD on dry pavement as damage to your driveline may result.
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No the front drive line is not designed to go faster then the rear
the front and rear should have the same gear ratio
ratios for the late 70s ford 4x4 are these
f150
front dana 44 came with these 3.00, 3.50, 4.09
rear 9" came with these 3.00, 3.50, 4.11
you will notice the difference on the last set is because of the manufacter variances but the .02 difference will not cause chirping
however if you lock into 4wd on pavement and turn in a tight circle you will get binding and wheel hop this is normal but straight line driving no just faster tire wear no chirping
check your gear ratios in your axles
the front and rear should have the same gear ratio
ratios for the late 70s ford 4x4 are these
f150
front dana 44 came with these 3.00, 3.50, 4.09
rear 9" came with these 3.00, 3.50, 4.11
you will notice the difference on the last set is because of the manufacter variances but the .02 difference will not cause chirping
however if you lock into 4wd on pavement and turn in a tight circle you will get binding and wheel hop this is normal but straight line driving no just faster tire wear no chirping
check your gear ratios in your axles
Posting Legend
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Many times the front and rear are set up with slightly different ratios, the front is always the faster ratio. When the exact same ratio is available then it is used. The problem comes when axles are mixed and matched and exact ratios are not available as in D44 front and D60 rear etc etc. Tire rollout due to loading can give problems also.
Posting Legend
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You can get worse than wheel hop... I call it "humping" 
It is caused when the suspension and frame flexes trying to make up for the difference in ground covered during a revolution of the driveshafts. When the flexures let go the wheel can hop or the body/vehicle just plain heaves and wallows, -very hard on U-joints and drivetrains!
It is caused when the suspension and frame flexes trying to make up for the difference in ground covered during a revolution of the driveshafts. When the flexures let go the wheel can hop or the body/vehicle just plain heaves and wallows, -very hard on U-joints and drivetrains!
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I was thinking about changing out my gears in my truck, and was told by a mechanic that my stock 79 F-150 had a DANA 44 with a 3.54:1 ratio up front, and the rear 9" had a 3.50:1 ratio. I found the tag on the rear axle, but have no idea where he got the number for the front axle ratio.
Mine hops on pavement a little bit when in 4 wheel drive. I've been told that if the gears are overly mismatched the truck will kind of wind up the suspenion like a car does when you brake race it.
Mine hops on pavement a little bit when in 4 wheel drive. I've been told that if the gears are overly mismatched the truck will kind of wind up the suspenion like a car does when you brake race it.
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Ok I'll throw the obvious out there... Along with gear ratios being the same, make sure you've got the same size tire all around. I only mention this since I actually saw a guy w/ a 4x4 the other day that had tires on the rear that were larger enough than the front to give the truck 2 - 3 inches of rake. I s'pose he liked the look and didn't use the 4x4.
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if it really does have a 3.54:1 ratio up front someone swapped in a Later model gear set. Because when Ford started putting in the 8.8 rearend they came in 3.55:1 and don't have the 3.50:1 ratio like the 9" has. The gears shoulkd be within 1% of each other to work without binding. 3.54:1 front and a 3.50:1 rear gives you 4% diffirence will cause lots of binding.
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No, the front axle was never swapped, the trucks been in the family since new. Like I said before I don't know where the mechanic got the numbers for the front ratio, but that is what he had told me?
Can anybody tell me what I do have, just so I know? This is what the door tag reads under the VIN:
133 S F141 TB4 A H2
06300 1979 14
Thanks,
Ron
Can anybody tell me what I do have, just so I know? This is what the door tag reads under the VIN:
133 S F141 TB4 A H2
06300 1979 14
Thanks,
Ron
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From: Boise, ID
Look for a tag on the front differential cover. The gear ratio will be stamped on it (if it's still there).
My front Dana 44 is equipped with 3.54 gears. My 9" rear has 3.50 gears. That is how my truck came from the factory.
FYI...both 3.54 and 3.50 gears are available for the TTB Dana 44 (I know, that really doesn't apply here).
Edit: I almost forgot. It's not a good idea to drive on dry pavement in 4wd with a part time system. It's really hard on the transfer case.
One more thing......
The only positive way to know which gears you have is to count the teeth on the pinion and ring gear then divide.
My front Dana 44 is equipped with 3.54 gears. My 9" rear has 3.50 gears. That is how my truck came from the factory.
FYI...both 3.54 and 3.50 gears are available for the TTB Dana 44 (I know, that really doesn't apply here).
Edit: I almost forgot. It's not a good idea to drive on dry pavement in 4wd with a part time system. It's really hard on the transfer case.
One more thing......
The only positive way to know which gears you have is to count the teeth on the pinion and ring gear then divide.
Last edited by 77'F-150Mudder; Nov 30, 2003 at 04:49 PM.
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Originally posted by clean79150
133 S F141 TB4 A H2
06300 1979 14
133 S F141 TB4 A H2
06300 1979 14
S.... is the paint code
F141... Mode code and GVW
TB4.... is the body code
A... trannys code which is a NP 4spd
H2...Axle Code is 3.50:1 LS
(?) should be another code right behind the H2 for front axle code
06300 Max GVW LBS
1979 year.
14... order code..
Posting Legend
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Originally posted by Txquadhunter24
if it really does have a 3.54:1 ratio up front someone swapped in a Later model gear set. Because when Ford started putting in the 8.8 rearend they came in 3.55:1 and don't have the 3.50:1 ratio like the 9" has. The gears shoulkd be within 1% of each other to work without binding. 3.54:1 front and a 3.50:1 rear gives you 4% diffirence will cause lots of binding.
if it really does have a 3.54:1 ratio up front someone swapped in a Later model gear set. Because when Ford started putting in the 8.8 rearend they came in 3.55:1 and don't have the 3.50:1 ratio like the 9" has. The gears shoulkd be within 1% of each other to work without binding. 3.54:1 front and a 3.50:1 rear gives you 4% diffirence will cause lots of binding.
3.54 & 3.50 -That is only a 1% difference...
((3.54 - 3.50) / 3.50) * 100 = 1.14
Fleet Mechanic
Joined: Aug 2003
Posts: 1,546
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From: Kemmerer, Wyoming
I think the bottom line here is... NEVER put a part-time in 4WD on dry pavement. If you do, you will get strange behavior and sounds, all varying depending on your tires, suspension setup, etc. Get the truck off-road (doesn't have to be mud, just any kind of low-traction situation) and see how it acts.