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General Forums => The Mess Hall => Topic started by: DanMarino on June 17, 2017, 07:42:29 PM
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Hi Everyone,
I have a 1994 YJ with the 2.5 engine and AX-5 tranny. I noticed a humming noise today when I would let off the gas while driving. When I was on the gas, no humming. It hummed when I was both in gear and in neutral.
Any ideas what I should be looking for?
Wheel bearings?
Some other bearing someplace?
Rear differential?
Driveshaft U joint?
Thanks for the help.
13
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Could be tires even. You're going to have to localize the sound. Best to drive around without the top and doors.
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Since I am deaf in one ear, I can't locate noises. So I'll have my son or wife give it a listen. In the mean time I'll check out the driveshaft u-joints as a start.
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When you say in neutral, are you still moving?
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Hi Jeffy,
Yes, I am driving the jeep. Doesn't matter what gear I am in or if I am coasting in neutral. If I'm in gear, and have my foot on the gas pedal there is no humming sound. As soon as I let off the gas, there is a humming sound that continues until I give it gas again. When I stop at a traffic light, there is no humming sound. So I've got to be moving.
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I'll take a look at the engine and transmission mounts too.
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So noise while under power only? If it was more like a can of ball bearings sound I'd suspect the driveshaft U-joints.
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I'll drive it again tonight and take a look underneath.
I must not be explaining it well. When I am driving the vehicle and let off the gas pedal, then I hear the humming sound. I'm not sure if it is a vibration or a hum, or where it is coming from. I'll start a process of eliminating components and report back.
Thanks again.
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Update. - Jacked up the passenger side of the jeep last night and did some investigation.
1. I didn't find any play in the drive shaft u joints. Front and rear u joints seemed fine.
2. I tried to wobble the front wheel up and down, left and right to see if there was any play. All seemed tight. Wheel bearings seemed fine.
3. I checked around the exhaust system to see if it was bumping or rubbing anyplace and all seemed fine there.
4. I did notice some play in the transfer case rear tailshaft. there was movement up and down or left and right when I applied pressure there. It moved maybe 1/8 inch or a little less. How difficult is this seal/bushing to replace there? Is it normal to have play at that point?
Thanks,
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How much lift do you have? How much of the slip yoke is exposed? Have you ever replaced the U-joints? I suggest greasing the upper U-joints and see if it goes away. I highly doubt replacing the rear seal will do anything. Play is caused by wearing on the output shaft splines and the drive shaft slip yoke. This us usually exacerbated by bad driveshaft angles.
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Thanks Jeffy.
I am stock on flat springs from 1994. haha. No lift for me. So the angle is not severe at all.
I'm pretty sure I have had a shop replace one bad u joint before. I'll take a look at my maintenance records. I'll also look and see if my u joints have grease fittings.
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It sounds a little like this, but only when I let off the gas. https://www.youtube.com/watch?v=EjoaGOrhQco
From what I have researched, it could be that the pinion nut needs to be tightened slightly. Apparently as things wear, there gets to be some slop in there and the angle changes slightly when the driveshaft is under load/not under load.
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If it's your pinion yoke you should be able to shake it and it would move. Pinion side shouldn't move. U-Joints typically sound more gravely though. I'd grease the U-joint and see if it changes.
That video sounds like tires or a worn pinion bearing. Smooth hum.
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For the heck of it I changed the transfer case fluid. Things were fine there.
Next I took the cover off of the rear differential. Metal flakes in the fluid as it drained out.
Found this.
(http://i.imgur.com/CfTk9Yv.jpg)
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Each of the 2 small spider gears have lost a tooth.
(http://i.imgur.com/7AzG1aX.jpg)
It sounds like the Dana 35's are notorious for exploding. People hate them.
I don't wheel this vehicle. It tows my kayak/utility trailer and gets me around in the snow. It sits in my garage probably 5 or 6 days a week.
The pinion gear teeth and ring gear teeth look fine. I'm not sure what else to check.
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Well, luckily, it didn't damage the R&P. Should be an easy fix then.
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Thanks Jeffy.
So is there anything else I need to replace besides new spider gears?
I'm guessing I need to start disassembly to see if I notice anything else that is bad.
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Thanks Jeffy.
So is there anything else I need to replace besides new spider gears?
I'm guessing I need to start disassembly to see if I notice anything else that is bad.
You're just going to have to disassemble it and check the surfaces. Keep in mind that if you change the side gears out there are two different kinds. Since yours is a '94, you should have an ABS carrier. Although, I don't think there's any difference in the actual spider gears. You might have to look for the Bill of Material number on the axle tube.
https://www.crownautomotive.net/Differential-Gear-Set/4740670.html
https://www.crownautomotive.net/Differential-Gear-Set/83503002.html
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Got the spider gears out.
(http://i.imgur.com/kKzoRe8.jpg)
The pin must be worn. The hole for the screw that holds the pin in place is definitely oval.
(http://i.imgur.com/9JmPZQ3.jpg)
Carrier bearings seem tight.
Pinion bearing seems tight.
Pinion and ring gears seem good.
Looks like I need 2 new new spider gears and their washer/shim things.
Looks like I need a new pin and a new screw to hold the pin in place.
Not sure if I need a new carrier.
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I've got a question about the side gears.
Do I need to remove the axle c clips first, before the side gears will pop out?
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I've got a question about the side gears.
Do I need to remove the axle c clips first, before the side gears will pop out?
Yes, because that's what holds the axle shafts to the side gears.
So take the drums off and push the axle in and you should be able to get the C-Clip out. Then slide the axle shaft out a bit and you should be able to take teh side gear out.
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Sounds good Jeffy. I'll try to get that accomplished tonight and I'll go ahead and order the gear set on the internet as well.
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Removed the rear wheels and brake drums. Pushed the axles in slightly and the c clips fell out. The side gears were easily removed. Ring and pinion look good. I'm going to order a new set of differential gears. It comes with 2 new side gears, 2 new spider gears, and the thrust washer things, a new center pin and a new screw to keep the pin in place.
(http://i.imgur.com/hsrNuRx.jpg)
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I'm trying to order the right gear set. Where do I find the casting number that is mentioned?
This ia a 1994 Wrangler with 4.11 gear ratio and Dana 35 rear.
Is this the correct part to order?
https://www.quadratec.com/products/52412_08.htm
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Have you taken out the side gears yet? I'd measure them. The difference is 1.62" vs. 1.56", I think. Non-ABS being the larger. Crown says that it depends on if you have the ABS option but I'm not so sure. Believe Jeep started using the ABS carrriers in Non-ABS Jeeps no matter what.
(http://eastcoastgearsupply.com/images/F64461363.jpg)
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Cool. The side gear was 1.56 inches.
So what's the correct part/kit to order?
The axle tube number that was stamped said. 605661-2 if that helps at all.
I'm lost here. haha.
Tom
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Here's the Dana website that talks about what is needed for my Axle number 605661-2
http://www2.dana.com/expertforms/deabill.aspx
If I am reading this correctly, I need the Differential Inner Parts Kit #707321X
Am I on the right track here?
Thanks,
Tom
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You have an ABS carrier so get the kit for ABS. This is what you want. https://www.summitracing.com/parts/sdh-707321x
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Thanks Jeffy, I ordered the new gears. Hopefully I can be back on the road this weekend if the gears arrive in time.
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The Good News: The new gears arrived and I installed them over the weekend.
The Bad News: I broke the head off of one of the differential cover bolts as I was torqueing the bolt down. Now I gotta drop the axle or gas tank to extract the bolt. No bueno.
The Other Bad News: There is still a humming sound when I am coasting. With the new gears, the humming is much quieter. Something else is wrong and I can't tell where from.
It's like when the drive train is producing forward momentum things are quite. Then when I let off the gas to coast, the humming noise starts.
Not sure what it is... Oh well. I'm getting discouraged. Need to get my son to help find the source of the noise as we are driving the vehicle.
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Was able to extract the broken rear differential cover bolt that I snapped the head off of.
Jacked the rear end of the YJ up in the air and secured with jack stands.
Lowered the rear axle so that I had just enough clearance to work on the broken bolt without interference from the fuel tank and skid plate.
Tried to center punch the broken bolt to make a place to start my drill.
Used a small left hand drill bit to drill through the center of the bolt.
Sprayed a bunch of WD40 as I was drilling.
Used a larger diameter left hand drill and expanded the hole in the bolt.
The bolt remnants gripped onto the drill bit spun out smooth as butter.
Threads seem fine. Just need to get a new bolt. :biggrin:
Still some noise when I drive and let off the gas. Not sure where it comes from.
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Could it be the 2 piece front drive shaft not disengaging and you hear the drive line operating the transfer case?
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Thanks Bootguy, how would I check this?
The front drive shaft should not be spinning when in 2 Hi, right?
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Stuff I'm reading sounds like if there is noise/humming when decelerating, then it is an issue with the pinion bearings.
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Put it up on jacks and turn the right front tire. If your driveshaft turns the axle is not disengaging.