[s-cars] Da Green Monstah goes back to da dyno

qshipq at aol.com qshipq at aol.com
Sat Oct 16 11:05:01 PDT 2010

 Agree wrt changing the design engineering on re-hardened axles = why?  I remember reading that Audisport just paint marked them lengthwise, and replaced them when they twisted more than 90 degrees in competition.  IIRC II, someone on MG is running 600+hp to the wheels and just replaces the axles at 180 degree twist.  I have also bent and snapped an 016 axle at steamboat on my urq, which I attributed to heat, twist and -20degree ambient.  The carnage was ugly as the axle twisted up into the brake line immediately.  The problem with re-hardening axles is that you are changing the flex/twist audi designed into the axle.  

As a rule, the amount of hardening of the axle is directly related to the duty of the splines at it's drive ends to the exact spec of the carbon steel used.  Most engineers design drive axles to twist significantly under heavy loads, to prevent the shock on the spline.  Put another way, you re-harden a stock axle, I would expect two things to happen besides the obvious (less twist being the assumed primary goal).  1) the duty cycle of the axle is reduced by definition and 2) the splines will likely become the weak link until '1' happens.

Before going at this because it sounds right, I'd sure want some data to support a change.  Paint mark the axles and see what the current flex does in terms of duty cycle and/or failure.  In the end, re-hardening the stock axle sounds expensive and frustrating.  If axle failure is a problem, have a new axle made all together.  It's not as expensive as one might think, this is done in the HD truck market right here in the US of A.

my .02

Scott J

-----Original Message-----
From: Peter Golledge <petergolledge at gmail.com>
To: John Cody Forbes <cody at 5000tq.com>
Cc: S-CAR list <s-car-list at audifans.com>
Sent: Sat, Oct 16, 2010 11:48 am
Subject: Re: [s-cars] Da Green Monstah goes back to da dyno


I'll second Cody's opinion, I'm running 400ft/lb in the LT-1Q which has been 
abused for more than
10 years in Auto-X, Steamboat, Asphalt events and joyrides.  I'm in Denver area 
also so my driving
includes lots of spin up the tires to 2X road speed on the ice then have them 
catch on the dry bits.
I run with Center/Rear locked on Steamboat/Ice stuff and that puts more load on 
the axles as

If the stock Type 44 axles can handle that the S6 should handle the little old 
300ft/lb of your
motor.  Now wheel bearings on the other hand... you are going to go through a 
few of those!


On 10/15/2010 10:15 AM, John Cody Forbes wrote:
> Are you sure you want hardened axles? The harder they are the more brittle 
they are. Personally I'd rather let them flex. The failure mode on most Audi 
axles I've seen is they bend. I'd rather bend one and limp home than BREAK one 
and have the two halves flailing around destroying things.
> -Cody (mobile)
> On Oct 15, 2010, at 10:48 AM, Hap Maguire<captmagu at gmail.com>  wrote:
>> Taka
>> The car is very easy to drive on the street. The power curve is so large that 
you don't have a sense of lag. The only real challenge is the clutch. Basically 
its a custom race clutch for the street that was concocted by Southbend with 
consultation from Dave Jones. For a hydraulic clutch its very heavy and Mr Jones 
specced it to hold 800 ft/lbs of torque. Nothing like the mechanical clutch on 
my Big Block Vette back in the day but stiff nonehteless. Its stiff but not 
grabby like a Spec. The turbo is at about 24 lbs of boost at 4500 rpm and full 
boost by 5000. The motor is making 300 ft/lbs at 4000 rpm.
>> As far as the rest of the drivetrain, the tires are the fuse right now. They 
break loose quite readily. Having that fuse eases the strain on the rest of the 
drivetrain. We are taking a set of axles in to a shop to have them hardened and 
we'll install them this winter. The 6-speed CRB was rebuilt and I had everything 
hardened by Mr. Klugge in Germany before it was shipped to me. 


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