[Fot] Racing a TR3 A Type Overdrive

[steve]

Hardy, I found your detailed OD info very illuminating.  No, I don't even run an OD unit in my TR3 but I enjoyed your write-up nonetheless.  I can see that you've put a huge amount of time and effort into pushing your machine to it's uppermost limits of power and reliability.  Very cool!

~Steve


-----Original Message-----
>From: Catpusher at aol.com
>Sent: Nov 12, 2012 4:28 PM
>To: fot at autox.team.net
>Cc: HRPTR3 at aol.com
>Subject: [Fot] Racing a TR3 A Type Overdrive
>
>Racing a TR3 A Type Overdrive  
>Please see what you can find in the archives. 
>For many years the TR3 was one of a very few cars  not allowed alternate 
>gearbox ratios in SCCA E Production. Using second gear  overdrive was 
>essential with a full race motor to bridge the gap between  2nd and 3rd. I spent 
>thousands of hours studying and  modifying the OD. Running a pressure gauge 
>during events is necessary, as is not  allowing it to leak on the driver. The 
>gauge will show when the solenoid is out  of adjustment, and most critically, 
>when there is a running pressure drop. If  the accumulator piston does not 
>reach the blow off holes, that oil no longer  gets to several parts. The 
>specks for the accumulator bore are very tight, and  honing to remove the steel 
>piston ring scratches will only work a few times. The  TR4A IRS/TR6 piston, 
>sleeve, and spring provide a much lower volume and  pressure, but a 
>replaceable sleeve is a good idea. Much research about piston  displacement and 
>pressure pointed me towards a Jaguar sedan assembly that was  NLS, but JRT, 
>with the help of a UK Jaguar club, provided a few sets of piston  and sleeves, 
>and I also located the matching springs. I did find it necessary to  run an 
>oil cooling system with an electric pump and MGC auto gearbox cooler, all  
>set low enough that it would not flow back into the gearbox during the early  
>laps before the pump was turned on. Keep in mind that I was running slicks 
>and  often ran where the track temps were high. 
>TR Regards, Hardy
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