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Pickups Dodge Dakota Dodge Dakota Suspension and Axles
113 messages, Last post on Oct 22, 2009 at 4:47 PM
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I have a 1990 Dodge Dakota, 3.9 L gasoline engine, two-wheel drive with about 150,000 miles on the odometer. I've been noticing a kind of "swish-swish" sound coming from up front by the wheels and lately it has been getting to be more of a "grind-grind" sound. It seems to happen twice per wheel revolution, although I could not swear to that. I put the front end up on stands and took off the tires and then the rotors and pulled out the wheel bearings, inboard and outboard, cleaned out the grease from them and the races and inspected them as well as I could. I spun the bearings but couldn't see, hear or feel any trace of roughness or wear. I regreased the bearings and put them back in the rotors and reinstalled everything. The noise was still there. I then put the right side up on a stand and this time removed the outboard bearing and put in a new one (just the cone, not using the race provided, but leaving the old race in the rotor). I reassembled and heard the same noise on road testing. I tried swapping the passenger side front wheel and tire with the rear, but found no change. I then put the old bearing back in and brought the truck to a tire shop and asked them to have a look/listen and give me an opinion. Their $20 result was to say that the tires are OK but I probably have a bad wheel bearing. I went home and bought a set of bearings and races for the passenger side rotor and took the cleaned rotor to a local machine shop to have the old races removed and the new ones installed. The shop also "cut" the disc surfaces because they said it isn't always possible to exactly match the position of the new race with the old race's position. I took the rotor home, installed the bearings and new seal for the inboard bearing and heard the same noise with a road test. Today I took the truck to another tire shop for a second opinion. That mechanic also road tested the truck, put it up on a lift and spun the wheels and his $15 opinion is that the problem was a bad bearing on the drivers side. I took the truck home and got another new set of races and bearings for the driver's side, but only installed the bearings, leaving the old races in the drivers side rotor. Road test showed that the same noise was still there. The only odd thing I have noticed in all this is that one of the wheel studs on the passenger side seemed to allow the lug nut to keep turning tighter and tighter. I didn't notice this last time I put the tire and wheel on, so maybe it was not really happening. I looked at the rear side of the stud and it hasn't pulled any deeper into the wheel, and I haven't noticed the stud itself turning. Would appreciate any guesses as to what can be happening.
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Replying to: dustyk (Mar 20, 2007 5:30 pm) In case it hasn't been brought to your attention yet, "LIVE FREE or DIE" is New Hampshires state slogan.  Enjoy all the info on this forum. |
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Replying to: tjfitz (Jan 12, 2008 3:36 pm) Getting back to the mechanic, he also held a mechanic's stethescope to the differential near the drivers side axle (this is a two-wheel rear drive pickup) and I could hear some noise, which he described it as a "growling". He didn't listen to the transmission near the output bearing, but said he is almost certain the problem is in the differential, or possibly the rear axle bearings. (I seem to get in a real no-brain state when talking to any mechanic at any shop, and didn't think to ask him to listen to the transmission, although I had left a typed detailed description of the noise, my work, and also left a new transmission rear seal I had bought a couple of months ago, in case he found that was the source of the noise.) He also had me get in the pickup on the lift and put the transmission in drive to hear the noise, and it was the same as I hear when driving, so I suppose that proves beyond a doubt that the noise isn't coming from the front wheels, but I'm not as certain about it coming from the differential and not the transmission. I'll take the truck in to another shop tomorrow for a "second opinion".
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Replying to: tjfitz (Jan 16, 2008 4:36 pm) Unless you find somone reliable to perform the differential rebuild, you may not be happy with the results. A shop that rebuilds differentials for racecars would have the skill. You may want to consider just having a complete rear-axle assembly installed from a salvage yard. The cost may be less than a differential rebuild. (and the warantee may be the same as a rebuild) Whatever you do, consider using RedLine lube in the differential in the future. The extra cost is well worth it considering it would have likely PREVENTED this failure in the first place. |
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Thanks for the comment, bpeebles. Went to a second mechanic and he agrees the problem is the differential. I rolled under the pickup this afternoon with one wheel off the ground, a jack stand holding it up. Then I marked the propeller shaft (drive shaft) with chalk and put a chalk mark on the raised tire and rotated the tire forward to get 10 revolutions of the shaft. I did the same on the other rear wheel. The result for both wheels is that 10 shaft revolutions make about 5 and 5/8 wheel revolutions, or about 1.78 shaft revolutions per wheel revolution. I think you're supposed to multiply this by 2 to get the gear ratio between the pinion gear and the ring gear, so I am guessing my ratio is about 3.56. I also took a photo of the differential from the cover end. There is a metal tag fastened under one of the cover bolts. I enlarged the photo and it looks to me as id the the tag has this lettering: "1|8.3" . Could this be 1 ring gear tooth per 8.3 pinion gear teeth? If I multiply by 2, this becomes 3.66. Am I figuring all this right? |
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I brought my 2003 4x4 CC. in for a front and rear diff fluid change to mr. Lube, they used mopar antislip additive and it was quiet for a couple days it actually sounded better, now its really noisy, sounds like the howl of an old army jeep. the cantire mechanic says its prolly the bearings and will be 600 to fix.how can this happen overnight, a friend suggested throwing in jacobs to quiet it down. Any ideas?
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| dodgeman, "I feel your pain." I am scouring the region's junk yards for 7.25 inch, 3.55 gear ratio rear axle assemblies for my '90 Dakota and not having much luck. I may have to remove the whole thing and put it on sawhorses in my freezing cold front porch and see if I can repair whatever is wrong inside the differential box. May have to rent one of those salamander butane heaters to keep from turning into a block of ice (I'm in North Dakota). | |
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I removed the cover of my 1990 Dakota's rear differential (it's a 2-wheel drive) and counted 39 teeth on the ring gear and 11 on the pinion gear. Stamped on the ring gear is this: 2852943 - 3.55, also 10 25 89. I'm guessing the 10 25 89 is the date of manufacture, October 25, 1989. I've measured the gear ratio by turning the tire and the drive shaft and got 3.56, which is close-enough for me to 3.55, so I think the "- 3.55" means the gear ratio. Maybe the 2852943 is the Chrysler part number. Can someone check this? I took a string and used it to measure the circumference of the ring gear at its widest and got about 26 inches. If you divide 26 by 3.14 (pi), you get 8.28 inches for the gear diameter, which is closer to published numbers for Dodge's 8.25 inch gear than to Dodge's 7.25 inch gear. But before this, I was told by a local used parts emporium desk jockey that the cover for the 8.25 inch differential is hexagonal while the 7.25 inch cover is rounded. My cover is rounded (actually elliptical), so he told me I had a 7.25 inch gear. On the Internet I read that "Ring gear diameter can be identified by observing the housing tube diameter. The 7-1/4 inch axle has housing tubes which are 2.5 inch (63.5 mm) diameter at the inner ends and 3.00 inch (76.2 mm) at the outer ends; the 8-1/4 inch axle has housing tubes that are 3.0 inch (76.2 mm) in diameter." My axle tubes are 3 inches O.D. for their whole length. Maybe this is another indication that I actually have a 8.25 inch differential. Am I doing the ring gear measurement wrong? Should I be measuring around the widest part of the gear, or somewhere else? Am I wrong in thinking I have the 8.25 inch ring differential, or is the parts man wrong? I'd sure be grateful for some help. I've never done any differential work, and this is the first time I've seen one opened-up.
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Replying to: tjfitz (Jan 27, 2008 1:30 pm) Most 2WD have the 7-1/4 while the 8-1/4 inch come thru installed on the 4WD Daks. Somtimes it seems that they installed whatever happened to be laying around the day the rear-axle was installed- LOL
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Replying to: bpeebles (Jan 27, 2008 6:26 pm) My elliptic-shaped differential cover has 10 bolt holes in it. Also found when I took off the cover that there is a second metal tag under one of the two bolts that I left on while draining the oil. It has what looks like 3.5 stamped on it. The other tag has 3.189 stamped on it. The pinion gear driving the ring gear has several numbers painted in white on its end face inside the case. 4 and 1 are two that I remember. |
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