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Ok, Tranny Tunnel is Off...

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pjsmetana

pjsmetana

Jedi Warrior
Offline
Randall, Andy, or anyone know knows...

This is a continuation of strange thumping sounds when slowing down, in gear or on the brakes, at low speed. Prompted the lug nuts change and now this.

I finally got my transmission tunnel off. I grabbed the U joint on the forward end of the propshaft, and shook the heck out of it, and there is a little bit of movement. Just enough to make noise, but I can't really feel thats its moving any amount. I don't actually see anything wrong, but I know from the sounds last time I was driving that there must be. There U joint is solid as a rock with no play at all. It seems to me like all the problem is with the OD.

Someone suggested I check the nut at the end of the shaft that connects to the prop shaft. Do I have to remove the + in the U joint or would the 4 bolts get me to that collar/nut thing described previously? Or is it both?

Should I now jack up the back end, and spin the wheels, listening for anything?

U joint and OD close-up.
1269893554.jpg


Tunnel is off. Nice Floor Pans, eh?
1269893557.jpg
 
Pete;

Yes, the four bolts will get you to the nut on the back.
Just a thought, have you checked for a tight U-joint?
I had a horrible noise in a car once, plus a vibration, and it was from a seized joint.
Good Luck, keep us informed

Dave :hammer:
 
The 4 bolts will get you to the nut; although getting the driveshaft out of the way enough to turn the nut may be a problem.

But if you can just barely feel the movement, I doubt that is the problem. Unless I've confused this thread with another one, it previously appeared that it was moving by 1/8" or more. .002" is probably normal.

Running the drivetrain on stands can be a great way to locate mysterious noises. Just make sure the car is secure on the stands (try to push it off yourself, while the jack is still underneath but not quite touching).

I'm not too familiar with Spits, but it might also be advisable to support the rear suspension. My Stags do all sorts of things with the rear suspension at full droop, that don't happen with it loaded.
 
One other thought, you have a U-joint at each end of the shaft, correct? If so, you might check that they are phased properly. The yokes on the driveshaft should lie in the same plane. If someone has assembled it wrong, it can cause odd vibrations.
 
14dna said:
Pete;

Yes, the four bolts will get you to the nut on the back.
Just a thought, have you checked for a tight U-joint?
I had a horrible noise in a car once, plus a vibration, and it was from a seized joint.
Good Luck, keep us informed
Click to expand...

Oh yeah, My U joint is really tight. I'm wondering if maybe its too tight... its still got red assembly grease on it... so I know its not been used much. I've only put maybe 80 miles on her in more than a year. Can I tell if its seized without attempting to remove the U joint?

Since it does not look like I can torque the 4 bolts without taking the U joint apart 1st... I 'spose I'll be removing both anyways.

TR3driver said:
...But if you can just barely feel the movement, I doubt that is the problem. Unless I've confused this thread with another one, it previously appeared that it was moving by 1/8" or more. .002" is probably normal...
Click to expand...

No, its definitely no where near 1/8 of an inch of movement!

TR3driver said:
...
Running the drivetrain on stands can be a great way to locate mysterious noises. Just make sure the car is secure on the stands (try to push it off yourself, while the jack is still underneath but not quite touching).

I'm not too familiar with Spits, but it might also be advisable to support the rear suspension. My Stags do all sorts of things with the rear suspension at full droop, that don't happen with it loaded.
Click to expand...

Man, this just sounds dangerous. I feel like I'm gonna end up in my beer fridge. How the heck do I support the rear while spinning the rear?? Jack stands I assume... but where is safe that I wont bust anything?
 
Pete,

I center jack the rear and put the stands foreward of the wheels on the frame.(works for me).

Randal,

only the early style propshaft should have a phasing problem. the strap type can be pulled without pulling the straps and the CV type only has 1 u-joint.

you are correct the Spit does make extra noise when the rear suspension is at full droop, BTDT.
 
Pete,

IMHO you are at this point, pull the shaft and check the u-joints for smooth movement in their full range. You may have a joint starting to fail.

I still have a noise in mine, one day I'll find it
 
I had similar thumping sounds and it turned out to be worn bushings on the differential. There's a lot of torque there and the diff was banging against the frame.

Jim
-------------
1974 Spitfire
 
JimSnack said:
I had similar thumping sounds and it turned out to be worn bushings on the differential. There's a lot of torque there and the diff was banging against the frame.

Jim
-------------
1974 Spitfire
Click to expand...

Where did the sound seem to originate when driving? Mine seems to come from right under the stick, maybe a bit forward of it. Granted, all my years as a Navy Pilot has made me hearing quite lackluster. I'm sure the heavy metal music from my ipod at the gym don't help either :smile:

I'm starting to wonder if maybe this sound can come from a dry or low oil level in my OD or tranny. It looks like I got quite a bit of gear oil on the top of my trans from around the rectangular plate.
 
Don_R said:
only the early style propshaft should have a phasing problem. the strap type can be pulled without pulling the straps ...
Click to expand...
Don, you underestimate the, uh, imagination of some previous owners. Ask "JimSnack" about just how strap-drive propshafts can be messed up! Thanks to the ol' stash o' parts in the barn, I had steak that week! :wink: (I'm kidding; I gave him a pretty good deal on a splined Spitfire propshaft!)
 
Andy,

thanks for keepin me in check...my glasses went all rose colored again...
 
Now that I think about it a bit more, I don't think this could come from low oil in the OD as it works fine, and needs oil pressure to work. Nor could it be low oil in the Trans as it shifts fine sans a once-in-a-blue-moon second gear crunch and does not wine. My Diff does not wine at all either. I also think if I was leaking any oil, there would at least be a spot here and there on my carpet (yes I park my car on its own carpet).

Today is too nice to work on it though... I think I'm gonna go surfing, as yesterdays storm has left some nice waves.
 
Slacker.

As I only half followed the original post, question: Where is the transmission supported? Talking of the rear crossmember/trans mount. If that's weak (or missing) the box can flail around and make thumping noises if loaded/unloaded.
 
tdskip said:
pjsmetana said:
Today is too nice to work on it though... I think I'm gonna go surfing, as yesterdays storm has left some nice waves.
Click to expand...

Right on! How were the waves?
Click to expand...

Awesome! Solid predictable 4 footers all day. It was even nice at low tide. Water was a bit chilly, but my wife got me a wetsuit in Jan for my birthday. What an awesome day.

DrEntropy said:
Where is the transmission supported? Talking of the rear crossmember/trans mount. If that's weak (or missing) the box can flail around and make thumping noises if loaded/unloaded.
Click to expand...

I'm not sure whats supposed to be there. It don't look to me like anything is missing around the mounts. Anyone got a picture or a list for me to use as a check against my mounts?
 
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