Bronco Forum - Full Size Ford Bronco Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
I'd like to preface this by saying I know little about Bronco's :)
And I did a search but could not find a discussion on this.

My friend has a early 90's Bronco II 4x4 Eddie Bauer 5sp manual, 200k miles, which just recently makes a nasty sound when accelerating fairly hard in 1st, 2nd and sometimes 3rd.
It sounds like if your muffler was scraping against the ground while you were driving, kind of a crunching/scraping sound.
It seems to happen when you hit the gas hard and the rear axle rotates due to the weight transfer/torque change. Sounds like it's coming from the muffler/driveshaft area.
If we floor it in 4th or 5th it is fine.
Our theory is apparently there are some gears attached to the driveshaft (?) and when the rear end rotates under load, those gears may not be messing correctly. :shrug ...and maybe the shocks are blown allowing the axle to rotated too much???
Anybody have any advise for easy stuff to check?
 

·
Yeeeeehaw Y'all!
Joined
·
2,038 Posts
Put a floor jack under the rear end and get both of the wheels up. Hand spin them and see what you hear? Check for excessive slop in both axels (yank in and out), check the U-joints in the drive shaft(s).

Poke your head under there and do a visual inspection? It is possible that something on the exhaust has come loose and is rubbing along the driveshaft somewhere.
 
T

·
Guest
Joined
·
0 Posts
I'd bet it's the driveshaft. has it ever been updated, or replaced?
Crawl underneath. grab the shaft with the truck in neutral.
Try to push it forward and backward. If you get any movement, it's bad.
You will see rubber boots at both ends, if they are torn, it's another good sign it is junk.

If the driveshaft has been updated, it will have normal u-joints at each end.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #5
It is most likely original, I'll try some of the ideas above. Is it a normal thing for the DS to go bad? Is it just U joints on either end or are there gears, etc?
 

·
Registered
Joined
·
5 Posts
Discussion Starter #7
They must really be shot to be making the noises I'm hearing, sounds like I'm draging my exhaust doown the road. I'll check it out and see what I see.
 
T

·
Guest
Joined
·
0 Posts
Yes BII drive shafts are junk. When mine went. I would accelerate in 1st gear, or second gear and hear it. When It first started you had to stand on the accelerator pretty hard, as it got worse it did it easier and easier.
It would shake the whole truck, sounded like it was hitting the muffler or something.

Would only do it acceperating, never when you let off.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #9
Did you just replace with a new oem unit or are there other options?
I suppose mine lasted 200k mi so that's not bad...


Also, our theory is *if* the rear shocks are blown, the rear end will rotate under acceleration more (each shock is at ~45 deg to the rear end right?) causing the driveshaft to wear quicker, so we are thinking of replacing the shocks as well, even though they are not the original ones.
Comments?
 
T

·
Guest
Joined
·
0 Posts
Your theory is correct, but it's not just the shocks. the springs are junk also.

If you put an updated shaft in you'll never wear it out, bad shocks or not.

When I went to get mine done, the drive shaft shop told me my only option was the updated unless I wanted to get one from Ford.
The updated shaft uses standard, cheap u-joints.

I think mine was $200
 

·
Registered
Joined
·
5 Posts
Discussion Starter #11
Hmm, this brings up a good question. My friend is just planning to get the stock oem DS from the dealer, Autozone, whatever...
Is there a better option? (type to get, place to purchase, etc)
I think he said the oem one is ~$200-250
 

·
Registered
Joined
·
63 Posts
saeds bronco said:
Hmm, this brings up a good question. My friend is just planning to get the stock oem DS from the dealer, Autozone, whatever...
Is there a better option? (type to get, place to purchase, etc)
I think he said the oem one is ~$200-250
I have one left over from a 9" swap, it is most likely like the one you have with cv joints instead of ujoints. Mine is a trw rebuild unit, may have as much as 50k miles on it now. Original one in my truck was junk at 80k miles, trw replacement went 175k and started doing same goofy noise, this one has gone as I said maybe 50k.
 
T

·
Guest
Joined
·
0 Posts
I had seen ads in the back of Four Wheeler or 4Wheel&Off Road that listed the update driveshaft. Not sure if those ads are still there or not.
Might be a better question to ask at the Rangerstation.com, or maybe one of the other members knows a good BII website.
You might be able to get it offline cheaper than what I had built.

The one rmyers2051 had probably get you buy for quite a while. If the truck already has 200k on it, really how many more miles you gonna keep it?
 
1 - 13 of 13 Posts
Top