Driveshaft?

[JonW]

I've been reading about driveshafts, and I have a question. I have 4.10s and a tune. I've had my car up to 125 in 3rd gear, and probably won't do that again. I like hard acceleration, I don't care that much about top end. Given the fact that my car will not see the dark side of 100 mph very often, can I stay with the stock driveshaft, or should I get an aftermarket shaft?

[Zack]

The stock shaft is good if you stay true to keeping it under 110 or so.

[Marauder386]

Yeah, that driveshaft wobble sucks @ above 110 ... thats why I have had the DynoTech shaft for a long time on my cars...


:cool:

[MENINBLK]

With the 3.55 gears, most people feel the wobble come on around 80+ MPH.
With 4.10 gears, it comes on a little sooner.

You may want to either upgrade your shaft or balance the OEM shaft.
It helps save the transmission tail housing from wearing out.

Where are you located ?

[RF Overlord]

^^^what MENINBLK said^^^

Unless you regularly exceed 80, there's no absolute NEED for the DynoTech shaft, but the problem is that once you reach driveline critical speed, the driveshaft flex harmonics can occur without you noticing and it doesn't take long to destroy the tailshaft bushing.

Quite a few people here have posted that they kept their stock driveshaft after installing 4.10s and have had no problem, but do you REALLY want to take that risk?

[O's Fan Rich]

I got a 2000 police car shaft, had it rebuilt and balanced. No problems since.

[fastblackmerc]

Has anyone had their stock driveshaft balanced?

[Glenn]

I had some vibration with the 4:10s and had a drive shaft shop balance the OEM drive shaft at high rpm. I have had no problems since.

Glenn

[merc]

What shop was that Glenn ?

[jdando]

I got mine balanced before my first HDPE. Had it up to 135-140 mph smooth as slick. Second school had it up to 140-145 mph and still smooth. Next school is in two weeks:banana2:

jeremy

[Blackened300a]

Quite a few people here have posted that they kept their stock driveshaft after installing 4.10s and have had no problem, but do you REALLY want to take that risk?

I have gone over 130 more then a few times since my 4.10's were installed with the stock driveshaft and I never had a vibration or problem.
If you are paranoid about it then have your stock one balanced, If still paranoid then step up and pay the $550 for the matrix but IMO, I dont see why.

[Meteorite]

There are two completely separate issues here:

(1) Driveline imbalance, which is the imbalance (in units of in-oz or the like) times the square of the rotational speed. This is the issue that is remedied by balancing a driveshaft.

(2) Driveshaft whirling, which occurs when the rotation speed of the shaft coming up to (or near) the first bending mode eigenfrequency of the shaft. Driveshaft balancing does not address this. Making the shaft stiffer in relation to its mass addresses it, moving the eigenfrequency up high enough so that the critical speed does not occur until a higher vehicle speed.

[Glenn]

Merc:

I had my drive shaft balanced at:

Drive Shaft Service
1395 Cobb Parkway, Suite L
Marietta, GA 30062
#770-427-4898

Ask for Ernie. Be prepared, it is not much of a shop, but look at the equipment they use and the large number of drive shafts they have to work on and for PU.

Glenn

[JonW]

OK... I had my car to 125 mph and didn't notice any vibration. But then again, I wasn't really looking for any, so unless it was very noticeable, I might have missed it. i was too busy looking for cop cars at the time.

So, even if my driveshaft is balanced (or if I have it balanced), that still does not address the other problem of the driveshaft whip, is that correct? If that is the case, then even a balanced driveshaft is suspect at speeds over 80 mph, correct?

If I didn't feel a vibration, should I let sleeping dogs lie, or should I proceed further.

[Meteorite]

OK... I had my car to 125 mph and didn't notice any vibration. But then again, I wasn't really looking for any, so unless it was very noticeable, I might have missed it. i was too busy looking for cop cars at the time.

So, even if my driveshaft is balanced (or if I have it balanced), that still does not address the other problem of the driveshaft whip, is that correct? If that is the case, then even a balanced driveshaft is suspect at speeds over 80 mph, correct?

If I didn't feel a vibration, should I let sleeping dogs lie, or should I proceed further.
Obviously, each driveshaft is going to have a little different imbalance. I would say if you were up to 125 without feeling any vibration, that is a good sign. In fact, my guess would be that it is already pretty well balanced to be able to achieve that.

When I had my stock driveshaft, the vibration became objectionable at about 95 mph.

It also matters whether or not you intend to run for a sustained period of time at high/ speeds. If you're just going to accelerate up to 125 and then immediately back off to a slower speed, I imagine you'll be fine with what you have. Some of the symptoms (like some failure modes associated with the tail shaft bushing) only arise after several minutes or more at extreme speeds.

[magindat]

OK. eigenfrequency is 'whip' and it's felt as a general roughness. Balance is vibration and is felt as a vibration. Whip is HARD to feel. I could only tell AFTER I had replaced my shaft and noticed MUCH smoother ride at all speeds, but more noticably as speeds increased.

Now you don't have to go CF or even Metal Matrix. DR has a Dynotech ALUMINUM shaft for a few bucks LESS that works wonderfully! I have it and as stated above have no vibration or roughness.

[wchain]

I took my driveshaft off the DTR when I first got it, and took it to a driveshaft shop and left it there for the day. Had it balanced and 'certified' well over any speed the MM is capable of.

He charged me 65 dollars and I never felt any vibrations, at least up to 143, but I didnt want to push anymore ;)