Clonk In Rear

[Paul McGuffin]

I just changed the read differential, thinking the one I had was bad. When driving along in 4th gear, if I back on and off the gas, I get a clonking noise in the rear. The U-Joint are both brand new. The new replacement does the same thing as the first. Both were bought used. I guess I could have purchased two bad ones. Any though here? I’ve got the job down to about three hours.

 

[Jim_Gruber]

Radius arm rods are your issue. 95% chance. Simplest is to buy new, check U.K. Sources for prices and save the old set fir rebushing. Watch where the shim / spacer goes when you remove the bottom bolts. An airgun is your friend and a come a long will help to rotate the axle to get everything to align so bolts can be reinstalled.

 

[Paul McGuffin]

I can jack the rear up, moves the wheels back and forth and recreate the same clonk. I guess I don’t understand what a radius arm is.

This work was done by British Car Service in Tucson about 2000 miles ago.
1 Removed both Radius Arm Links
2 Pressed out 4 old rear Radius Arm Bushings
3 Press in 4 new rear Radius Arm busihings
4 Installed both rear Radius Arm links

So, with all that work, can it still be the problem?

 

[Gerard]

Paul, don't you have wire wheels? That sound is likely from worn splines in the hubs. When changing directions, the wheel can slightly rotate on the hub.

 

[Jim_Gruber]

Concur w Gerard if that is the case.

 

[Paul McGuffin]

Went for a longer test drive. This new/used rear differential in much better. Before, everytime I shifted gears I got the clunk, now just when I back off gas real quickley. ****, my 92 Toyota truck does that. I still get the noise when I take the rear wheels off and rock the brake drums. The splines on the axle and wheels are fine.

 

[woolfman]

Went for a longer test drive. This new/used rear differential in much better. Before, everytime I shifted gears I got the clunk, now just when I back off gas real quickley. ****, my 92 Toyota truck does that. I still get the noise when I take the rear wheels off and rock the brake drums. The splines on the axle and wheels are fine.

It could be the wheels inside the diff cage. I recently rebuild my diff with new new bearings, and when I disassembled the planet gears I discovered that the shims were through. After I replaced them and checked their contact pattern, play was absolutely minimal. The further they´re out from the center (eg worn shims -> less centered contact on teeth), the more play you have there.

One of many points where you can collect play:
Axle splines/worn
Planet gears/sun wheels --> shims worn
crown wheel/pinion --> worn/wrong play
propshaft to drive flange --> loose
propshaft/worn u-joints
gearbox mainshaft/worn splines


My 2 cents.

 

[JPSmit]

Before you get too complicated lie under the car and tighten every nut you see. that took care of my clunk.

 

[JPSmit]

Before you get too complicated lie under the car and tighten every nut you see. that took care of my clunk.

and that response just sounds wrong. :grin:

 

[Paul McGuffin]

The whole rear of the car suspension has pretty much been rebuilt 2000 miles ago. The fact that the new/old read end stopped 75% of the problem seems to make be believe, what’s left of the problem is another worn rear end. Buying used parts on eBay is a roll of the dice. On a related subject, is there anyone who sells a better rear differential gasket than Moss Motors? Their’s is just thin paper and next to impossible to put on and not tear.

 

[Jim_Gruber]

Possibly U Joints, but also Axle U Bolts, They do come loose and need to be really tight. Make sure Radius Arms Bolts are tight. Bushings could have been replaced but if someone forgot to tighten the radius arm bolts you could have a clunk there. Look in the MOSS Catalog for a BE Rear Suspension and you will see the Radius Arms and the two bolts on each side. There is also a spacer that needs to go on the correct side that keeps the radius arm straight. And since I need to install lthe Radius arms this week on Bugsy, Which side does the radius arm spacer go on. Pumpkin Side or Brake Drum side of the axle.

 

[JPSmit]

The whole rear of the car suspension has pretty much been rebuilt 2000 miles ago.

Much like re-torquing - my clunk was the spring hangers all tight all needed re-tightening as they bedded in . just sayin...

 

[nomad]

I think Wolf likely has the source. Not uncommon for the clunk to be the axles in the spiders or the spiders themselves. Give a kid with good hearing a ride and see if he can pinpoint it!:friendly_wink:

Kurt.

 

[woolfman]

On a related subject, is there anyone who sells a better rear differential gasket than Moss Motors? Their’s is just thin paper and next to impossible to put on and not tear.

Soak it in water and let it dry, then apply. It should stretch itself during drying up.

 

[nomad]

Soak it in water and let it dry, then apply. It should stretch itself during drying up.

Or make your own....I'm pretty much done buying gaskets that don't fit. A little time consuming to make but at least they will fit then.

 

[Jim_Gruber]

Paul,

I just made my own and installed it last night. Started with a roll of gasket material.
placed gasket material over top of studs and stretched tightly.
Took a small brass hammer and tapped the top and bottom stud to make an impression on the gasket material
Used a Leather Punch Kit - Largest size punch tip was same size as studs - Kit was all of $5.00 at Hobby Lobby or Michael's
refit gasket over two studs and placed nuts on top and bottom to hold barely in place
Repeated process of tapping L and R studs while holding gasket material tight
Punched out 2 additional holes, placed gasket material over 4 studs and tapped remaining 4 studs to make a make


with 8 holes now punched, I checked gasket carefully to make sure all holes aligned and trimmed with leather punch as needed. I used a wooden board under the gasket material BTW while I was punching it out.


With gasket fully seated I trimmed the outside to fit with an Exacto Blade or Utility Knife with a sharp blade

Outside gasket material removed, I followed the same process to trim out the inside. Check inside the Diff to make sure no material fell into the diff and everything is clean on the inside


I cleaned all oil and grease and junk off of mating surfaces with a painting PreClean. Lots of dirt and grease came off an already cleaned pumpkin mating surface.

Applied thin layer of Hylomar, Hylomar is a wonderful product that seals but does not get hard. Spread the layer thin being careful around Studs and applied gasket when Hylomar got tacky


Google Hylomar Blue to order on line to get the real stuff. Mfg in Cincinnati now.


coated top side of gasket with thin coat of Hylomar. and again used PreClean on the pumpkin side. Again lots of dirt and grease came off.


Installed Pumpkin, Tapped into place with a piece of wood. Added new bolts and lock washers,


Tightened by hand and short socket wrench in a Star Pattern Criss Crossing on opposite sides until all felt tight.


Walked away for 10-15m and used torque wrench. Could not find Torque Values to used same sized bolt value for Rocker Arms which is 25 ft pounds,

Tightened to 15 lbs in Star Pattern. Kept going round and round at 15 lbs until all were uniformly tight at 15 lbs. and then followed the same procedure to torque to 25 lbs going in a Star Pattern.

I was amazed that the same bolt tight at 25 lbs. needed 2-3 repeat attempts to torque it at 25 lbs to get a uniform torque on the diff on every nut.

Followed at the end with a clockwise circular torque and still found a few more nuts that would take a little more torque to get it to 25 lbs.


Does it leak? Will know in another week. And yes I hope I don't have a clunk when I put the wheels on the ground and the tranny in gear.Don't know yet but this entire process of gasket making took all of 15-20m and actual Pumpkin Install 20 m tops.


Hylomar, good good stuff. With Free Shipping 2 tubes around $25 on Amazon from a Range Rover Specialist out East.

 

[Paul McGuffin]

I found the “clank!” I’m too embarrassed to tell everyone what it was, but I will. It might save someone else the same head aches. The rear brake shoes were really in need of adjustment. When I would back off the gas, I guess the shoes were so loose they would bank against something. Well, now I have a perfectly good extra 3:92 rear end.

 

[JPSmit]

I found the “clank!” I’m too embarrassed to tell everyone what it was, but I will. It might save someone else the same head aches. The rear brake shoes were really in need of adjustment. When I would back off the gas, I guess the shoes were so loose they would bank against something. Well, now I have a perfectly good extra 3:92 rear end.

TaDa! Love a simple solution!

 

[Paul McGuffin]

TaDa! Love a simple solution!

Yeah, the solution was simple. Getting there was the problem.