[Mgb-v8] [Mgs] Miata rear end

[edd.rogers at GM.COM]

James, In an AWD vehicle there is a central differential that doles out 
the power to front and rear of vehicle.  Typically there is 60% alloted to 
the main axle and 40% to the secondary.  If the vehicle's basic design is 
FWD then the majority of power goes to the front axle. So, all I am saying 
is that one needs to exercise due diligence before going forward.  If the 
rear diff is only designed for 40% then it probably will be massively 
overstressed if 100% of the torque is applied since the V-8 at least makes 
similar torque to the Rendezvous' engine. This would be bad.  In research 
on internet it appears that it is a varaible system that will allow up to 
70% of torque to a particular axle so not as bad as I was thinking 
initially.  The engine used made about 250 lbs/ft so, you are within 
design when no more than 175 lbs/ft go to the rear diff.  There is 
probably a safety margin built in of some amount. I just don't want to see 
someone go to all the work and R &D and then blow the diff.


Edd Rogers
A Unistaff employee representing General Motors
Sales Engineer
MD Business Center
31 E Judson St
Pontiac MI  48342
Ph:  248.874.3503



"James J." <m1garandusa at verizon.net> 
01/12/2009 07:36 PM

To
edd.rogers at gm.com, mgb-v8 at autox.team.net
cc

Subject
Re: [Mgb-v8] [Mgs] Miata rear end






Edd,
    What does that mean?  That one has to de-rate the drivetrain's max 
safe torque rating by 40% when calculating if it is strong enough for 
the MG, or are you describing some kind of clutch mechanism in the input 
of the rear differential that decouples/unlocks above a certain torque?
    If it's the former, we would also have to take in account the MG's 
light weight vs. a Rendezvous (~2500lbs vs. ~5000(?)).
T-5 transmissions are typically rated at a much lower torque than they 
can actually handle in a British car.
    Does anyone know if it shares internals with another common design?
V/R
James.

edd.rogers at gm.com wrote:
> I don't believe that the Rendezvous rear is capable of full torque.  It 
is 
> an AWD based off FWD set up.  I think it only is designed for about 40% 
of 
> torque.
>
>
> Edd Rogers
> A Unistaff employee representing General Motors
> Sales Engineer
> MD Business Center
> 31 E Judson St
> Pontiac MI  48342
> Ph:  248.874.3503