250 GTE 'Rumble' in drivetrain

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Zanny1
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Location: Fountain Hills, AZ

250 GTE 'Rumble' in drivetrain

Post by Zanny1 »

After a year at the repair shop (long story), 3177 is back home. It now has a rumble in the drivetrain, which is most noticeable at 100 KPH. Since there were many repairs done to the car since having it last, I am interested in the forum's opinions as to how to approach this.
1. The transmission and overdrive were rebuilt. The overdrive had noisy bearings and a few other issues. The transmission had bearings, synchros and the main shaft replaced. I now have a 2nd gear that can be shifted up/down at speed with no synchro problems. Both units appear to be quiet and operate as they should.
2. The rear springs were removed and re-arched to add about 2" to the rear ride height. The results are fabulous - no more squat and with new bushings the ride is solid and precise. Is it possible the repositioning of the rear axle has moved the driveshaft, and it's connections, where a worn part is now making this noise? Would running the car with the rear off the ground help identify the source of the noise?
3. All four Borranis went to Cork Adams for refinishing. They were fitted with new Blockley 205/70 VR rated tires. I suppose it's possible that one of the tires is bad, however I think this is unlikely.

And finally, with all the cold weather we've had here in northern Arizona (15-35 deg each day), I've had to use the choke to start the motor when cold. No choke - no start. I never thought I would have a vintage Ferrari that required the use of the choke. And yes.... when "opened" all the linkage moved freely back to the proper driving position.

I will post some pics of the before and after ride height in another post. Happy new year to all.
Mike
Mike
1971 365 GTC4.... on my second one
Timo
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Re: 250 GTE 'Rumble' in drivetrain

Post by Timo »

Opinions ? Well, as a "professional" restorer and vintage car services provider, here's mine, although it should be applicable for any (service) industry.
First, unless there are severely compelling reasons not to, I would highly recommend consulting person(s) or shop providing final assembly/installation/testing/etc of the any & all the major components included in aforementioned "(long story)".
Not only should they be afforded the chance to correct (or refuse to ?) any possible issue involving their work, but with their recent direct involvement should allow best position to start the process of elimination to discover & sort out the problematic component(s).
Any other approach, as first, could easily lead to after the fact and sometimes unjustified "finger pointing".
Timo
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Re: 250 GTE 'Rumble' in drivetrain

Post by Timo »

P.S. Allowing another service provider to take over will likely lead to additional and possibly excessive cost over-runs since they may have to dig deeper just to gain full understanding of the all previously performed work and since they're now becoming responsible for the outcome.
Timo
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Zanny1
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Re: 250 GTE 'Rumble' in drivetrain

Post by Zanny1 »

Having had the car gone for so long, I neglected to search previous posts.... and sure enough a lengthy post about precisely the same problem. So I now have to figure out how to approach this, as I am in a remote area with limited resources for repair.
Will keep you all advised, and welcome any comments.
Mike
1971 365 GTC4.... on my second one
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tyang
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Re: 250 GTE 'Rumble' in drivetrain

Post by tyang »

Hi Mike,

Diagnosing a "rumble" is going to take more data. At 100 kph, does it go away with higher speed? Does it come from the front, or the back of the car? Under load? On deceleration? In gear, out of gear? Clutch in, clutch out? There are a bunch of things that it can be, and as Timo said, you could be chasing a lot of directions. Wheel bearings, pinion bearings, u-joints, UN-balanced drive shafts, all can make this noise. Also, the frequency of the rumble will also give you clues as where it's coming from.

Good luck!

Tom
'63 330 America #5053
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Zanny1
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Re: 250 GTE 'Rumble' in drivetrain

Post by Zanny1 »

Hi Tom
The low frequency rumble can be heard and felt in the seat.
It begins as the car gathers speed and is most noticeable at 100 KPH.... that's when you can really feel/hear it.
The frequency does not change with speed.
The noise does seem to diminish as speed exceeds 120 KPH, but that could be because of road noise or any number of things.
It is definitely in the back. Load/no load/transmission in neutral, clutch in/clutch out, overdrive in/out - all the same.
I am tempted to put the rear on jack stands and see if I can duplicate in the shop....... although the thought of revving it up to speed in gear doesn't appeal too much. I live on 12 acres, so maybe do it out in the field.

I think the key clue is that we had the rear springs, differential, overdrive and transmission out recently. I am confident everything went back together correctly...... my engineering voice says something that was OK before the work is now not OK. As you know, when you change out one thing it can cascade into the appearance of other gremlins.
Mike
1971 365 GTC4.... on my second one
Jumprun
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Re: 250 GTE 'Rumble' in drivetrain

Post by Jumprun »

I know you don't think it's the tires but why not switch the wheels front to back? It's about the easiest thing to eliminate.

Tom M.
John Vardanian
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Re: 250 GTE 'Rumble' in drivetrain

Post by John Vardanian »

You might try driving the car with the rear axle lifted off the ground and see if you notice any change.

john
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michaelbalk330
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Re: 250 GTE 'Rumble' in drivetrain

Post by michaelbalk330 »

this the kind of noise/sensation my 330 had- and it was a cheap repair- pulled the driveshaft, and had it balanced. the "feeling it in the seat", in my opinion, supports the driveshaft. I am not familiar with the 250 and its driveshaft (s) but pulling it on 330 was an easy job. Also, after I replaced the rear diff oil with 250W, the drive line was even smoother. you can start with the tire rotation already mentioned but I think feeling in the seat of pants is a clue.
Michael
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SLM
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Re: 250 GTE 'Rumble' in drivetrain

Post by SLM »

John Vardanian wrote:You might try driving the car with the rear axle lifted off the ground and see if you notice any change.

john
John is correct. This is the first thing I did to identify my driveshaft problems. I put the car on a lift and ran it as we observed the driveshaft rotation. I had many of the same symptoms you had. Check my previous posts.
Steve
62 250GTE S/N 3733
afwrench
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Re: 250 GTE 'Rumble' in drivetrain

Post by afwrench »

Hi Mike,I am not familiar with the driveshaft setup ie slip joint or not but is it possible that the u joints are out of phase. Mike
72,365gtc4,14681,2007 599 GTB
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Zanny1
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Re: 250 GTE 'Rumble' in drivetrain

Post by Zanny1 »

Zac Dugger was kind enough to come by the house yesterday. We ran the car with the diff off the ground and had a good look at the wheels, tires, driveshaft.... everything looked and sounded great. Tracking down the noise, it appears to be a pinion bearing as the sound is clearly in the center of the differential. So it looks like the car's got to go back to the shop and get a rear end inspection and replace the noisy bearing(s).
As with so many things Ferrari, and vintage, you fix one thing and another thing pops up. It's a pity, since the motor, transmission, overdrive and suspension all make the car a pleasure to drive since it was repaired and set-up correctly.
Mike
1971 365 GTC4.... on my second one
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tyang
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Re: 250 GTE 'Rumble' in drivetrain

Post by tyang »

Hi Mike,

I feel your disappointment, but am glad Zac figured it out. Like you said, old cars have problems like this, but solving it is part of the triumph of ownership.

Good luck!

Tom
'63 330 America #5053
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