Triumph Repair: POP NOISE REAR END?, axle shaft, wd 40

Question
QUESTION: Hi Jim, Glad to see your back.. I am having problems with pop noise on my 1972 spitfire IV. I have looked at this is what I have found so far. The noise happen in first gear taking off  ,and if I push the gas and let it off I can get it to pop. If  I turn to the left at a slow speed I get a pop also. If I down shift let the clutch out I get a pop noise. if the car is sitting and I push the car backward in gear I can get it to pop..  

what I have looked at so far took the D/P side wheel off tried to push and pull the drum in every direction everything seem solid. bush are all there not in the greatest condition but no movement. I replace the u-joint on the drive shaft. I didn't replace the axle u-joint but I don't see any play or movement when I move the tires back and forth. Could this be the rear diff? I do see it leaks and might be low on oil. would this help the problem? Any ideas to to help me quit popping ,and get me in the right direction?

ANSWER: Mark,

It sounds like something is getting torqued under acceleration... then moving back when you decelerate.

Check to make sure everything is tight in the driveline, including the bolts that hold the differential to the frame.  Top up the differential (it needs to have oil regardless) and see if the problem dissappears.

If not, something has too much slop in the driveline.  U-joints are a common culprit... but I've even had the axle shaft ends start cracking at the keyway (where the hub mounts) the can also give a similar effect.


Cheers,

Jim

---------- FOLLOW-UP ----------

QUESTION: Hi Jim, thanks I started today by spraying wd-40 on the u-joints axle shaft mount bolts. for about 4 hrs and then started wrenching. Found the problem right away after the rust was gone. The bolts that hold the axle shaft to the diff. Were sloppy lose. Then I wiggled the bolts seemed as if the the hole were much larger then the bolts. I am wondering if this might have been loose for a while ,and is it possiable I made the holes bigger with the slop.or is this normal? I wrenched everything tight and now the problem has now left. wooohooo Yesss..

Next question I have the new u-joints want to start this after a week of wd-40 everyday. Whats the best way to do this remove the axle shafts? Or go at it with a big C-Clamp? and step by step info would help.. Thanks mark

Answer
Mark,

If the prop shaft bolts were loose for a while it's possible that either the bolts are worn a bit or the flange holes have elongated.  As long as you keep the bolts tight it shouldn't be a problem.  Now you know what to check.

As to the U-joints, I've never had success doing them on the car.  It's a hassle undoing the brake line and parking brake cable, but much easier when removing/replacing the u-joint.  

Remove the circlips on the u-joint caps and wire brush to remove any corrosion in the flange.  Soak them with lots of penetrating oil.

One method that seems to work well is to hold the axle shaft in your hand and hit the u-joint cap area with a rubber faced dead-blow hammer.  

The c-clamp method also works.

The only trick I've figured out for installing the new u-joint is to load the caps with a bit of extra grease to help hold the needle bearings in place.  Using the c-clamp to gently press the caps in works much better than tapping with the hammer.  Just be careful, it's easy to get a needle bearing out of place in the cap.


Cheers,

Jim