[928uk] Fwd: Re: PSD operation] & Tyre pressures]

[Mark Nichols]

That makes sense. Considering my everyday journeys are mostly 30 - 50 mph & I always check and adjust for longer runs, I'll give it a try. I seem to remember the TPS warning can be overridden with a resistor? I wonder if one could make it variable threshold with a variable resistor... The intention being to retain TPS function but be able to set at a preferred trigger point.

Cheers



---------------------------- Original Message ----------------------------
Subject: Re: [928uk] FW: [Fwd: Re:  PSD operation] & Tyre pressures
From:    "Paul R. Smith" <smiffypr at clear.net.nz>
Date:    Thu, February 9, 2012 10:35 am
To:      928uk at lists.928.org.uk
--------------------------------------------------------------------------

I used to drop the tyre pressures in the winter by about 5psi, but didn't have RDK. The standard tyre pressures are set to prevent overheating at high speeds, but don't allow the tyres to warm up on cold, wet, straight roads.

The RDK sensors are temperature dependant, the given pressures being for 20C, so you should be able to get away with a little less in the cold weather, but probably not enough to get extra grip without the warning going off.

Smiffy

On 09/02/2012 23:25, Mark Nichols wrote:
> Thanks Smiffy, I am pleased the function appears correct. You are 
> right, I need to gain more experience. First car I have driven with an 
> LSD and last night was unintended. Just poor driving. Cold night, cold 
> tyres and poor road surface all conspired. I run standard wheels and 
> T1R tyres at handbook pressures of 44psi rear and 36psi front. My TPS 
> system works and nags readily if pressures drop by more than about 
> 2psi. 44 Seems quite high for the rear. Do any 928'rs run at reduced 
> pressures at all or is the 44psi considered optimum? I havn't run 
> these tyres far enough to see if they are wearing in the middle yet.
>
> Regards Mark N 90GT
>
>
>
> ---------------------------- Original Message
> ---------------------------- Subject: Re: [928uk] PSD operation From:
> "Paul R. Smith"<smiffypr at clear.net.nz> Date:    Thu, February 9, 2012
> 9:57 am To:      928uk at lists.928.org.uk
> ----------------------------------------------------------------------
> ----
>
>  That all sounds like it is working correctly. The PSD does back off 
> the locking gradually.
>
> In a cornering situation, with an open diff, the inside wheel would 
> loose grip, limiting the torque to the outside wheel, allowing it to 
> keep the rear end in line. With the PSD preventing the inside wheel 
> spinning, it allows you to apply more throttle in the same situation, 
> so when both wheels loose grip the back end goes more sideways. So, if 
> you are using the extra grip that the PSD gives you, you need to be 
> extra careful. Lifting off the throttle sharply makes it worse.
>
> You really ought to practice in a safe place rather than on a sharp 
> country bend.
>
> Smiffy
>

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