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Thunk from the chunk

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sjuengst

sjuengst

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The last time I took Muffy (Mk 1 BT7) out for a ride, I noticed a rythmic thunking noise (felt it in my seat too) which seemed correlated to the wheel RPM (as opposed to engine RPM). It sorta sounded like the driveshaft U-joint was hitting the frame. Yesterday, I put her up on jackstands and got under the car and looked around. Visual inspection of the driveshaft showed no sign of contact. Then, with the engine running and in gear, I felt the gearbox, OD, and differential, and could feel the thunk in the differential most of all. So it looks like I need to a tear-down of the chunk to see what's going on.

Here's my question: I'll be moving soon to a house about 10 miles away. Do you think it'll be ok to drive her there with this noise coming from the differential, or should I rent a trailer for this short trip? I'm not going to take her apart until she's safely in her new garage.

Thanks,

Stu
 
Had the car previously/recently been towed on a trailer, while left in gear?

The noise you describe sounds like when my car had a single tooth broken of the pinion gear__as a result of towing the car on a trailer, while in gear.

Can you drive it ten (10) miles? Maybe, are you talking 25-35 mph surface streets or 70 on the freeway? Me; I'd probably drive it__gingerly!
 
About a year ago, I trailered her from Florida to Texas on a car-carrier trailer like this, but I have driven her a good bit in the interim before the noise started:

28249_390406874482_6623294_n.jpg


The roads to my new house are 4-lane surface highways, most traffic goes about 60mph. I could drive slowly in the right lane, but don't want the Healey to look bad of course! I guess going slow looks better than sitting on a trailer, though! :wink:

Thanks,

Stu

PS: that's me and Dad on the day he handed her over to me.
 
Great picture Stu! I hope you get to pass it along in a similar style someday (looks like you've still got a few good years left :wink: ).
 
I finally got around to moving Muffy to her new home. I decided to drive her there (rather than trailer) and we made it without issue. On the trip, I noticed that the clunking only happens upon deceleration and/or downhill. When going uphill or accelerating, it goes away. My friend who followed me in my daily driver suggested that might imply a u-joint issue rather than the differential. Does this sound likely?

Thanks,

Stu
 
Or a loose pinion flange. Drop the shaft, manually check the joints for roughness (or tightness) in rotation, dragging the offside with you hand to simulate load, and angle the joints a bit, too. Check the pinion flange for looseness and play.
 
A few years ago i had a similar problem with my friendss healey. When i got inside the diff i found a plastic cap off a hypoid oil bottle.---Keoke-- :laugh:
 
Hey Stu,
Great picture of you with your Dad ! Need to tell us the story of how he got the BT7 or how long he had it before passing it on to you. Always great to read stories of a father passing on a car to his son. As to the clunk, check the pinion bearings too as I had a BN6 that would make a very noticeable 'whine' when you backed off the throttle. Realize that it was not a clunk, but on load you get no noise, apparently just when the diff is not under load. If it was mine sure it would be the more difficult of the two to fix !!!
Good luck,
Mike
 
Hi Mike,

Do you get "Healey Marque", the magazine of the AHCA? Keep your back issues? I wrote up our story for the September 2010 issue. Made the cover too! If not, let me know and I'll repost the article here. The short version is that Dad and I shared the LBC hobby when I was in HS and college. I had a series of TRs and he bought the Healey in 1978. Eventually, his arthritis got so bad he couldn't get in and out of her anymore, so he suggested I take her and keep her running. I was happy to take on that burden! :wink:

PS: we used to take famiily vacations to Edisto Island, SC every year. I love that area.
 
Hey Stu,
I'll look for the article as keep my old Healey Marque copies ! Real small world as I live on another island that is 8 miles across from Edisto Island. I can look out from my home and see Edisto across the water from Harbor Island where I live, next door to Hunting Island and Fripp Island.
Regards and good luck with that clunk !!!
Mike
 
Take the tunnel off and drive around the block with a passenger and put the brakes on to see if there is any movement in the engine/translission, you may find the source of the clunk that way. - a word of warning - Do not wear anything loose or trailing like a scarf though and keep fingers away from moving parts!

:cheers:

Bob
 
So, after moving and holidays and such, things finally settled down enough to take some time to diagnose the clunking noise. Turns out it was the knockoff hub retainer nuts on the driver's side were not quite snug. As the wheel rotated, it would shift around on the studs, making the clunking noise. I had checked the wheel for play early on, but was testing for lateral play, whereas in reality it was vertical play. Simply tightening the lug nuts solved the problem! Glad I don't have to disassemble the differential! I still can't explain why it only made the clunk upon acceleration and uphill, but not decelerating or downhill.
 
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