yo,
I'm w/Bob & Hammerhead12 on this; I have had same rear clunk from Drive Shaft Slip Joint since I bought it new
could be a few things..
Rear Clunk:
slip shaft needs greasing
Worn and/or loose driveshaft U-joints/rear axle universal joint ******; Remove driveshaft and place on a suitable workbench. Check U-joints for seized bearing cups. Check U-joints for smooth rotation operation
Loose suspension components; Loose rear spring U-bolts
Excessive ring and pinion gear backlash
EXHAUST SYSTEM; Raise vehicle on hoist. Check for broken or loose clamps or brackets
Inspect running boards, grounding body to frame, antennas, visors, bug deflectors, etc. (if equipped).
Inspect wheels and tires
CHECK DIFFERENTIAL LUBRICANT:
Check for low lubricant level.
Lubricant Chart for a 94 by Mikey see Note @ bottom of 2nd chart for Traction-Lok Friction Modifier
Check for wrong or poor grade axle lubricant.
INSPECT AXLE HOUSING; Check for exterior signs of damage
-----------
Bronco driveshaft is two pieces that slide together. slip shaft is normally covered by a rubber boot in the middle like in the diagram below..."; miesk5 note, slip yoke is often referred to as the Slip Shaft Spline
Slip Shaft Spline Lubrication pic in a 95; "...If your bronco suffers from the notorious thunk this is a good time to **** your shaft.."
Source: by TRUCKY18 (Bco)
Driveline Clunk as Vehicle Starts to Move Following a Brake Stop (Two-Piece Driveshaft); "...Loose rear spring U-bolts. TIGHTEN U-bolts to specification. Worn or galled output driveshaft and coupling shaft splines. REMOVE the driveshaft from the vehicle. CLEAN the male splines and INSPECT for worn or galled splines. REPLACE if necessary. Worn or galled driveshaft slip yoke splines. CLEAN and INSPECT the female splines of the driveshaft slip yoke for worn or galled condition. REPLACE if necessary. Damaged driveshaft slip yoke seal. REPLACE seal. Insufficient lubrication in driveshaft slip yoke. Using a long handle (stencil type) brush, APPLY grease evenly on all the splines of the driveshaft slip yoke. REINSTALL driveshaft and using a hand grease gun, LUBRICATE the driveshaft slip yoke through the grease fitting. Use Premium Long-Life Grease XG-1-C or -K or equivalent meeting Ford specification ESA-M1C75-B. NOTE: Install the driveshaft slip yoke, making sure that the coupling shaft and driveshaft are in phase..."; Miesk5 Note, Premium Long-Life Grease XG-1-C ESA-M1C75-B is available as Castrol MP Multi-Purpose Chassis Grease is a NLGI #2 lithium based, water resistant grease or ConocoPhillips Moly Poly Grease NLGI No. 2
From Ford, 96 Bronco Workshop Manual; same for your year
The Bronco rear driveshaft is of the double Cardan type which incorporates two universal joints, a driveshaft centering socket yoke (4782), and a driveshaft center yoke (4784) at the transfer case end of each shaft. A single universal joint is used at the axle end of the driveshaft.
Rear Driveshaft and Coupling Shaft, Bronco
get under and see if there is any side to side movement with the ujoints on the shaft, there shouldnt be any side movement at all;
than grease your slip-joint and go from there
by ElKabong (Ken, El Kabong); "...When you check the u-joints as Spiked described, park it on a flat spot, block the wheels & put it in neutral. That way the driveshaft will be free to move if the u-joints are bad..."
Source: by spikedzombies (O' Black Betty) & by ElKabong (Ken, El Kabong)
To grease slip yoke; cut the boot retaining ring clips
slide the boot over the shaft. grease splines & pull boot back over & use zip ties to hold boot in-place.
This is how FORD describes it;
cut the driveshaft slip yoke boot clamps (4K227) with sidecutters. Remove and discard the clamps
Separate the driveshaft slip yoke (4841) from the splined stub shaft on the driveshaft.
Remove the slip yoke boot. Inspect the slip yoke boot for rips or holes and replace if required.
If, during inspection, the driveshaft and coupling shaft boot is found to be cracked or split, the grease should be checked for contamination. Check the lubricant by rubbing between two fingers. Any gritty feeling indicates a contaminated driveshaft slip yoke and stub shaft. If driveshaft (4602) is operating satisfactorily and the grease does not appear to be contaminated, add grease as described in the assembly portion of this procedure and replace the slip yoke boot. If the grease appears contaminated, disassemble the driveshaft, clean and inspect the stub shaft and driveshaft slip yoke for wear. If splines are excessively worn, replace driveshaft.
If required, remove and replace the U-joints.
Assembly
Install the slip yoke boot with the small diameter side facing the splined stub shaft on the stub shaft. Push the slip yoke boot as far as it will travel on the stub shaft.
Install a small driveshaft slip yoke boot clamp and crimp the clamp using Keystone Clamp Pliers T63P-9171-A.
Compress the slip yoke boot and coat the stub shaft splines with Premium Long-Life Grease XG-1-C or -K or equivalent meeting Ford specification ESA-M1C75-B.
Fill the slip yoke boot with approximately 10 grams of Premium Long-Life Grease XG-1-C or -K or equivalent meeting Ford specification ESA-M1C75-B.
Slide the large driveshaft slip yoke boot clamp onto the barrel of the driveshaft slip yoke.
Align the blind splines on the splined stub shaft and in the driveshaft slip yoke. Push the driveshaft slip yoke onto the stub shaft.
Remove all excess grease from the slip yoke boot and driveshaft slip yoke surfaces. Position the slip yoke boot over the driveshaft slip yoke boot groove.
Move the driveshaft slip yoke in or out in order to obtain the distance of 10 inches between stud shaft weld to the centerline of the driveshaft slip yoke U-joint
Before installing the new large slip yoke boot clamp, make sure that any air pressure which may have built up in the slip yoke boot is relieved. Carefully insert a screwdriver between the slip yoke boot and the driveshaft slip yoke and allow the trapped air to escape ("burp") from the slip yoke boot. THE AIR MUST BE RELEASED ONLY AFTER THE DRIVESHAFT IS SET AT THE SPECIFIED LENGTH
Position the new large driveshaft slip yoke boot clamp over the slip yoke boot and groove in the driveshaft slip yoke. Crimp the driveshaft slip yoke boot clamp with Keystone Clamp Pliers T63P-9171-A
< <'>
