Under Tray
- Thread starter Bungditin
- Start date
What Stephen said - pretty common and probably one is on a forum for sale somewhere too. I have one that I've removed but will keep. Removed for better under engine access and 'to keep an eye on things'. If you are going to fit one make sure all the tray brackets exist and haven't corroded away and your rear wing riser works and wing curtain is in one piece.
Bungditin said:
TBH, I think you'll find the jury is out on that one from other long-term 964 owners. I sprint mine often on 5-hour day long trips and usually @ 5k revs. Highest oil temp reached @ 110oC (or just above 09:00 position on gauge). Quality oil a factor too.
Typically a service centre wouldn't deviate from the Porsche standard and fair enough. However, the undertrays were primarily for undercar aerodynamic efficiency in Porsche needing to achieve acceptable overall fuel efficiency values (leading to regulatory US emmission reqs). Undertray slots were added to improve what would have otherwise been lack of heat removal. No undertray - less high speed motorway under car aero efficiency (if ever high speed of course).
As always though, it's down to owner preferences, as it should be.
Stephenjk
PCGB Member
Most people removed tray to improve cooling. I hadnt heard it made it worse.
if your car's cooling is fine you could easily cause yourself a fair amount of time and money and end up with more problems than you started with by putting the tray back on. That is my experience on these types of jobs. Even doing something relatively small can turn into a surprising amount of work once fixings rust and stuff breaks.
if your car's cooling is fine you could easily cause yourself a fair amount of time and money and end up with more problems than you started with by putting the tray back on. That is my experience on these types of jobs. Even doing something relatively small can turn into a surprising amount of work once fixings rust and stuff breaks.
They were installed to meet noise regulations but they simply trap heat hence the reason many are removed.
On the issue of heat it is more important to check the oil cooler fans are working correctly. I would guess the low speed fan is not working on more than 75% of cars. When its working correctly the oil temp will be held around the 8 o'clock marker in standing taffic. If your temp gets to the 9 or above then chances are the low speed fan isn't working. High speed operation is about the 10 o'clock mark.
On the issue of heat it is more important to check the oil cooler fans are working correctly. I would guess the low speed fan is not working on more than 75% of cars. When its working correctly the oil temp will be held around the 8 o'clock marker in standing taffic. If your temp gets to the 9 or above then chances are the low speed fan isn't working. High speed operation is about the 10 o'clock mark.
colin129 said:
My opinion on this would be that specialists wouldn't advise either way tbh, and I wouldn't expect them to. Deviating from what Porsche built or intended isn't really in their interest to advise the opposite (on the record of course). I think for most owners we rely on the experience, skill and knowledge of others who might know or have practised and have credible feedback from. Rennlist is full of undertray technical debate. Seems ensuring that heatshields around the bottom half of the engine remain in place, and not removed either, is the key issue. Personal preferences as always dictate I guess.
colin129 said:
Unless checking in particular for the low fan speed operation it's not readily apparent if it works or not tbh. It was my Indy who said most don't work, they didn't see this as a big deal but would be more concerned if the high speed fan didn't operate for obvious reasons. I would doubt if many specialist could accurately tell you the operating temps for the fans tbh.
Bad balast resistor is often the cause or as in my case the CCU driver was defective. I've just rebuilt my engine so would rather keep the temps around the 8 o'clock mark in traffic rather than see the temp climb up past 9 o'clock before the high speed fan kicks in. I have installed a low speed manual override to do just that.
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