Thump, Thump, Thump, Thump?

I was driving the jeep around the block yesterday, I took off from a normal stop sign and normal speed and my tires screeched and then all the sudden I heard a thump, thump, thump, thump, whenever i drove. The sound is right underneath me and only happens when I'm engaged in a gear. When I roll in neutral it doesn't make the sound.

I figured It might of been a broken driveshaft slapping the tub but they are fine. I'm thinking it's a transfer case??? Any input would be great,

Thanks

 

Try putting the transfer case in neutral and going through the gears. Then disconnect the rear driveshaft, leave the hubs unlocked and put the transfer case in gear, and go through the gears. This may help you to isolate the noise to the transmission, transfer case, or the axles.

 

The transfer case gears turn with the drive shaft so if it is not making noise when coasting or with clutch in then it's not in the transfer case but could likely be a broken tooth in the transmission.

 

I will play with this today see if I can make any progress

I hope this isn't the case but it's looking like it might be.


Also another problem I noticed, is when I leave the jeep in 1st gear when parked, I can push the jeep as if it were in neutral.

 

Just 1st or all gears?

I submit that your clutch is maybe failing.

 

I had a similar experience with a Willys MB & a T84, and yes, it was a broken gear in the trans.

 

I found a local guy selling a 3 speed transmission from his 71 jeepster that had a buick 225. This should bolt right up, he's asking $250 for it, Without knowing whats wrong with mine, you think it'd be easier/better deal to buy this one and slap it on?

 

It may not just slap in.. Due to the torque of the 225 V6, they were pretty rough on light 3-spd trannys such as T-14, T86, T-90-modified. We don't know what engine or tranny you now have and before buying any tranny you need to open and look inside at the gears.

 

A '71 will be a T-14 attached to a Dana 20. The '71 has a special bellhousing that goes with the transmission - no adapter. So you can only adpat that end if you have the adapter and bell that came with your presumably V6-T14-D18 '70 CJ-5. If you have another drivetrain combination, it won't fit. You will also need the output gear (bull gear) from your V6-T14-D18 Jeep, since the T-14 has 10 splines and won't work with the 6-spline gear used with the T-90 and a lot of other Jeep transmissions.

 

and it probably needs rebuilt too.

 

Or you will luck out, and from the description of moving it while the engine is off, and tranny is in first gear, the center hub of the clutch friction plate has come loose and there is nothing wrong with the tranny at all.

 

AHH! too many options I don't know where to start! I do know that I cannot push it in 1st gear anymore, so I'm not sure what the deal was, but it seemed to work itself out. I just need to find time to start wrenching I guess.

If this helps troubleshoot at all, the noise is a thump, almost like somebody is playing the bass drum, and it sounds right under my seat, or in between the drivers seat and passenger seat. It's not a clicking, or a grinding sound, just a thump. Only happens when engaged in a gear, I was in 2wd when it happened.

For those who asked earlier, I have the original buick 225 motor, and as far as I know, original transmission.

 

One of the front wheel bearings in my '66 Olds Dynamic 88 went bad and did the 'Thump! Thump! Thump!' thing. That was noticable to me as being toward the front and Passenger side. I replaced both at the same time.

Could maybe be a bearing in the tranny or TC gone bad. The 'Thump!' is from what-ever shaft moving sideways in the bearing.

 

sorry for no updates, We are in the process of building a new house, and selling ours, and the relator suggested that I move as many cars out of the garage to make it look bigger and cleaner. Any ways we conducted a risky evaluation on the jeep the other day. Had a buddy lay on a creeper underneath it and grab the frame while I slowly moved in gear. He isolated the noise to the transmission.

So now I need to see if I can find a local shop that can do a rebuild on it. That's my only option, I am not skilled enough to do any transmission work. I can handle motor work, but when it comes the the delicate process of transmissions, I'm lost!

 

I broke a tooth off one of the gears in my transfer case. Does it sound like this?

[video=youtube;-MqwYTpKCx4]http://www.youtube.com/watch?v=-MqwYTpKCx4&list=UUEujULl9-e25BLs8Arw6mvA&index=8&feature=plcp[/video]

 

If you can't find a local shop, you can box it up and send it to Herm to be rebuilt. www.hermtheoverdriveguy.com Apparently he has some affordable way to ship transmissions. But I'd take the top off and look for the broken gear before I came to any conclusions.