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Discussion Starter #1
I have been trying to figure out the mysterious vibration problem in my '67 Super for sometime now. I finally got feed up and had a "real" mechanic give me his opinion. After driving the car he put the car up on all fours and ran it in gear and mentioned he heard something in the gearbox and that he thought the drive-line (which I thought was the culprit) seemed okay.

To give some background on the car: It is a 1967 Giulia Super that I have changed out the stock 1600 with a rebuilt and balanced 1750. I kept the 1600 5-speed by using a clutch adapter from Centerline. When I rebuilt the original box I did the synchro upgrade to the newer style. The drive-line has a new giubo, center support bearing, spider style transmission rear mount - ? and new u-joints.

After doing all of this work and making sure the drive shaft is in phase I have a strong vibration at 40 MPH to 70 MPH. The vibration happens in gear or out of gear coasting down hill (clutch engaged or disengaged).

SO getting to my question, could a strong vibration under my seat be caused by something a-miss in the gearbox if the car shifts fine and there is no metal "jewelry" when I drain the gearbox oil? I should also mention that I took the giubo and front of the drive-shaft off (again!) and inspected the output flange. The nut was tight but I noticed the stake-down washer wasn't staked down anymore. I also notice that one of the nuts on the drive-shaft side of the giubo was loose but I don't think that is the problem.

I apologize for the long-winded description but I am at the point of pulling the rebuilt gearbox out and busting it open just to make sure I didn't miss something. AAAArrgh! It seems to me that the kind of vibration I am experiencing would require the rotating mass/problem be south of the transmission - ?

Things that it might be - incorrect giubo installation (am I missing something here?), loose output flange nut, transmission, Centerline clutch mod, wrong rear transmission mount -??

Any suggestions would be appreciated,

Scott
 

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Scott,

I have a very similar vibration that I can feel in the seat in my 72 Spider. Kind of a low frequency growl or rumble. I suspect it is the diff. carrier bearings, as my driveline also is in excellent condition and not suspect. I'm going to swap diff's to see it it helps. I have done lots of seraching on this and it seems to most likely be the problem. I wouldnt tear into the trans. until you are sure it is not the diff.
 

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I'd make sure the trans output yoke nut is tight, and did you measure the ball on the trans output shaft, and the bushing in the front of the front driveshaft section, to make sure they're a good fit? If the ball is worn, it allows the driveshaft to wobble, further wearing itself out, messing up the giubo, and allowing the driveshaft to run off center, hence a vibration.

This should be under the sedan or trans discussion, not GTA.

Andrew
 

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Discussion Starter #5
Thanks for the suggestions. Sorry about posting it in the wrong section - I didn't know this was the GTA discussion.

Unfortunately I have taken the whole driveshaft to 3 different shops with an used output flange and they all say they cannot balance this type of drive shaft because they have no place to attach the front of the shaft to their equipment.

I didn't measure the ball but it looked in good shape. I should mention two things - I did put different (yellow) springs on the front and back that lowered the car about an inch. Also before I changed out everthing and had the wornout 1600 engine and gear box it didn't have any vibration (or 2nd gear synch)

I have a friend that has a differential out a Spider he rebuilt but isn't going to use (he later found a limited slip version) - will this work in a Super. I did notice about a 1/8" play in the diff input flange when I rotate it by hand.

Scott
 

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Where are you located? Maybe someone can suggest a driveshaft shop. On the d/s also check the sliding splines, if they have a worn spot that will cause vibration, the wear can be determined by visual and/or hand inspect and it will show up when balancing the shaft. Lowering the car will alters the wear pattern/point on the d/s.
The spider differential is a direct replacement, the question is what gear ratio?
In the past I've had a couple 105 cars with very firm springs that have induced difficult to diagnos speed related vibration., Have you replaced all the rear suspension bushings? and with what material? Also along with looking at the splines on the output shafts, check rear wheel bearings.
 

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If you have a vibration in or out of gear it sounds to me as if it is from the transmission back to the rear axle. Is the front yoke aligned properly with the rear U-joint? I know it sounds silly, but that can make a huge difference. Even one spline off can cause problems. Is the center support in good shape? If it has any age on it, that can cause the driveshaft to move.

Put the car on a lift and drive the car in gear. The vibration will show it self easy in 5th gear at 40 mph with a good mechanic watching to see what is happening.
 

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Discussion Starter #8
I am located in Tulsa, Oklahoma. I have taken to one driveshaft shop where other members have taken their driveshafts for balancing and but the same answer.

I just try running it with the giubo on just the transmission side but no driveshaft. It isn't real smooth but looking at the spinning giubo it looks pretty stable. I don't know if that is a valid test or not. It almost feels like I need new motor mounts but those are brand new too.

The center support bearing is brand new and was installed by a drive-shaft shop.

I checked the phase of the yokes on the driveshaft and they seemed to be lined up. If it is off a spline would you see a difference - ? I am wondering if I rotate it 180 if that would help.

The thing I keep thinking is that it is something I did after the rebuilt engine , transmission and driveline - like I said no vibration before with the 1600.
 

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Hey, at this point rotate the yoke 180 and see what happens. If it doesn't work at least you can say you tried it. If it works, I can see your grin all the way over here. :)
 

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Find a place that does truck driveshafts; they should be able to handle it. Take the output yoke, donut, and all the hardware along, and of course, mark everything to be installed as it came out.

Andrew
 

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I will reiterate what Andrew said earlier. A major cause of vibrations in older 105s is the wear in the ball on the back of the mainshaft and the mating bore on the front of the propshaft. You can balance the shaft and throw as much money at it as you want, but if they are not is good nick, it with go on merrily vibrating your teeth out till the cows come home. The amount of vibration you feel through the gear lever is a good indication where it is coming from. So after you have checked the rear section as below, check the these. Check for a flat section running around the outer of the ball, and then inside the spigot for a groove... there should not be any! You can buy and replace the spigot bush (simple), but the mainshaft requires transmission disassembly. And: Stuff lots of grease in there when you reassemble ensuring the seal is there!!!!

Misaligned and/or seized/worn uni joints and worn spines in the rear part of the propshaft is another cause of vibration. Take the rear section alone to a reputable shaft centre.

As for the front section... well unless it is bent, components like this usually have a reason for being out of balance. They just don't "go" out of balance.
 

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balance is not the major problem here it's the alignment of the drive train.
Have it on a lift and see what it does when you run it in gear as "VELOCE" also mentioned earlier.
 

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Discussion Starter #13
Thank you for the suggestions. I did eleminate some of the vibration by inverting the metal piece under the center support bearing (early 105 cars) to be installed in the correct manner. Always check the simple stuff first - boy I felt stupid. Before I reinstalled the drive-shaft I measured and checked the ball on the output shaft and found no excessive wear however when bearing in the prop-shaft I found a slight grove - ? Sort of matched the dimension of the ball. I also double-checked all of the u-joints and spines and re-greased 'em. Everything on the drive line - u-joints, center bearing, & giubo are all new.

Anyway, I put everthing back together with a lot of care to apply the proper amount of grease and torque settings and drove it around town and later to a club event. As I mentioned earlier, the main vibration was gone (by installing the support bearing plate the right way - duh) but I found a slight vibration and loud, low "growl" from the gearbox - especially prominent in 5th. After the club event on the trip home the "growl" went away until I got about 3 miles from my house on a 20 mile return trip. I know this may sound odd but it seems to emit the sound from the gear box only when I have it warmed up. If I were to discribe the way it drives - the engine spins freely with it in neutral or with the clutch disengaged but feels like it is fighting something when engaged. I am getting close - I think.

Thank you again for all of the suggestions.

Scott
 

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Discussion Starter #15
I just changed the gear oil this weekend from a Redline MTL to a Castrol 80-90. I filled it until it started to come out the side filler hole so I think I got enough.

Scott
 

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You did say you rebuilt the gear box, did you put in a new input shaft bearing? This bearing takes the load from the engine and can wear to the point of having some wobble to it. A new input shaft bushing on the crank is always a good idea at rebuild time and not that expensive. I am doing both the bushing and bearing when I do an over haul.

Did the old oil and drain plug come out clean? The main shaft does make a fair amount of noise spinning around at idle. You should compare your trans to someone elses to see if yours is making excessive noise. If there was one bad bearing, it could make a grumbling sound.
 

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Discussion Starter #17
Yes, the 1600 gearbox was rebuilt with updated syncros/sliders and I will check my receipts but I believe that I replaced the input shaft bearing and I know I replaced the bushing (that one you don't forget the tricky r&r). I have successfully rebuilt two other ALFA 105 gearboxes but this one is a little different because of the syncro mod (pretty straight forward) and the Centerline clutch adapter that allows a 1750 or 2 litre to mate with a 1600 gearbox -

http://www.centerlinealfa.com/cgi-local/SoftCart.exe/online-store/scstore/p-CP501.html?L+scstore+whnf8954ffc572c5+1212801594

When I drained the old oil it came out clean and even though they all have that "smell" it didn't seemed burnt. I will drive my brother's 74 spider and compare the sound per your suggestion. Was I correct in changing out the Redline MTL Synthetic with Castrol 80 - 90w?
 

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Changing oil is like asking if someone likes brown socks or blue socks. There is a lot of opinion on here as to what is best to use. I have redline in my wifes gear box and it is perfect. I have used Valvoline Synthetic 90w and that works too. If I want to get original I have Shell Spirax here and maybe some old Dentax.
Glad to hear you did a good gearbox. I would drive it and enjoy the drive.
 
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