30th droptop

iTrader: (-1)

Hi guys,

I have a '99 T/A 383 stroker that makes 418 RWHP. So far, I've kept things in the drivetrain stock. I've only had the car at the strip once, but I'll be taking it back soon. It's a street car and will not be regularly raced. I'm looking for wisdom about the driveshaft. Has anyone broken a stock aluminum shaft at this HP level through an A4?

I don't want to spend the money on an aftermarket aluminum shaft, so I'd probably run a stock steel shaft if I don't run the stock aluminum. But I figure there's probably some small advantage in regards rotational inertia if I keep the stock aluminum shaft.

Oh yeah, and my 60-foot is about 1.8 running DRs.

Thanks.

HCI2000SS

iTrader: (2)

You're fine with the stocker

JRENIGAR

iTrader: (37)

I have run mid 10's @ 130 or so in a 4000# car cutting 1.70 60's on the stock alum ds and u joints. I simply upgraded for safety reasons as I dont like to push my luck. You should be fine.

01ssreda4

iTrader: (96)

Auto with 1.8 60fts I would much worry about anything drivetrain related.

RPM WS6

iTrader: (3)

I never broke anything in the 7.5" rear or the aluminum DS with my A4 car even in the high 1.6x range.

30th droptop

iTrader: (-1)

Thanks!

Omega Doom

iTrader: (2)

out of curiosity may I ask the rest of your mods?

RacerX2

I have a M6 car with bolt-ons i.e headers, exhaust, intake and like it's mostly street driven with maybe a weekend or 2 a month at most at the track on street tires (not drag radials) and at an HP level similar to yours, maybe even a little less. And I will tell you honestly you are on borrowed time at the track. I have broken 3 sets of ring & pinions and one stock driveshaft (at the top end of the track 107mph when I let off the gas - scary) . If you saw how thin the factory driveshaft is with cardboard inside and how much damage it can cause when they fail, you would think twice about up grading your d/s. Having one let go on me a the track made me go with a steel D/s. Its heavier and slowed me down maybe a tenth or two. But with a mostly street car it was worth it for peice of mind. Like you, at the time I didn't have the coin to upgrade to an aftermarket alum. d/s like I would have preferred. I you have an auto, you may get by longer. But when you start upgrading like a looser torque converter or drag radials. The same will ultimately happen. Sometimes the damage can be done at the track and not show until your driving on the street like when I messed up my first set of gears. They let go just pulling out from a shopping center!Hope you have fun with your ride, It sounds nice.

RPM WS6

iTrader: (3)

It's not really a comparable situation. The M6 cars have been known to break rears and stock aluminum driveshafts at stock/near stock power levels. The concern isn't remotely as serious with the A4 cars - even with drag radials and a higher stall speed. That's not to say that A4 cars don't ever break these components, they certainly can, but the urgency of concern is much less and with only 1.8 60-foots from a car that won't see the track very often, I wouldn't lose a single minute of sleep over the factory rear and DS. Keep wheel hop away and there won't be much to worry about in this application.

01ssreda4

iTrader: (96)

Not a bad idea to pull your DS and install Precision 223 solid ujoints.

blackandgold

iTrader: (2)

Our M6's eat 10-bolts for breakfast. The A4's at OP's power level and 60' times would be fine. Once the 60' times start getting down to ~1.6 I'd start shopping around to be safe.

HioSSilver

iTrader: (8)

I ran to 11.1 on the stock ds and 11.0 10bolt with a m6. Auto's should be fine even faster. Didn't break the stock ds just found a carbon one.

MidwestChassis2

iTrader: (1)

The fact is the stock aluminum driveshaft is a weak link and there is many more factors that play into effect than HP numbers and 60' times such as old U-Joints, possibly surface damage from years of street driving, out of balance, and so on.

If you are going to abuse your vehicle you must consider what a weak driveshaft will cost you if it does break. You are now not only looking at the cost of a replacement driveshaft but possibly exhaust, broken brake lines, broken fuel lines, damaged torque arm, and even the worst possible issue if it makes it way into the cabin.


As far as performance gains or losses due to a driveshaft swap. Your average vehicle will not see much gains or losses in either direction just from a driveshaft swap from heavy to lighter or lighter to heavy.

DANOZ28

iTrader: (1)

even though i have a DS safety loop, i read somewhere factory shafts can be out of balance & cause vibration so since i wanted new U-joints and my stock steel shaft was rusty crusty & the new aluminum was lighter i thought it was a good idea.

blackandgold

iTrader: (2)

I don't think anyone is going to tell you that replacing the stock d/s is a "bad" idea.

RPM WS6

iTrader: (3)

Not "bad" but not a primary concern, and often unnecessary, for mild-moderate A4 street applications with limited track use.

senicalj4579

iTrader: (41)

Mine hasn't broke. Its got 130k on it and I have been know to beat it up a little.

SPDEMON

I've bent a stocker on the STREET on road race style tires, in a car that put down 390rwhp. So if you plan on making drag racing a habit, get a loop.
I'd just run the stocker, and when you bust it, get another one, they aren't hard to find these days it seems