PDA

View Full Version : O/D on or off at the track



02SVTKID
04-12-2006, 10:52 PM
Like it says leave the over drive on or off at the track. And please explain is one way safer than the other or what?

L8 APEX
04-13-2006, 07:44 AM
Do I need to explain what automatic transmission means:D Leave it in drive and race. The only thing O/D off means is it will hit the rev limiter at 5800rpm and then break something.

RUNVS
04-13-2006, 09:09 AM
Unless you are running big HP or 4:10 gears, I'd suggest turning the O/D off. The 3-4 shift puts a substantial strain on the motor at WOT and your MPH will likely not be high enough to warrant the shift anyway..... especially in the 1/8 mile.

I started turning mine off several years ago after learning a valuable lesson while bracket racing. I left the O/D on, had a short lead at the top end of the track, throttled down slightly to protect my dial-in as we approached the traps, and the truck immediately shifted to O/D once I let up. My opponent closed the gap faster than I expected and as a result of the unexpected upshift, I was at the wrong RPM level needed to nose him out.

Mark #2
04-13-2006, 10:46 AM
I run with the OD off.
Go through the traps at 119 mph/4900 RPMs
3.55 gears, 28" slicks.

wesman
04-13-2006, 11:20 PM
Ask Ron what he thinks now :hammer:

--wes

01REDL1TNG
04-13-2006, 11:43 PM
Id listen to Terry. We all know he knows what he's doing or we wouldnt ask him all the time.

L8 APEX
04-14-2006, 12:15 AM
Without doing real math the approximate numbers for 3:73 trucks for 3-4 shift @ 5400rpm and 120mph. The only reason for O/D off is if you plan on letting up or playing other bracket racing games. Or if you want to run the RPM past shift point towards rev limit which I set at 5800 on most stock trucks. So rev limit 5800 should be in the high 120's on a stock 3:73 truck.
Rob was hitting 4th at Hallsville with his KB 11:30's at 122 I think...
Rocks always ran with O/D off and never had a problem on motor since he trapped under 130 with 30" slicks. Unfortunately his first pass on the NX threw him into the rev limiter. Which may have led to his recent engine failure.
So I would suggest folks know their RPM limits before locking the truck in any certain gear. I had a customer run the Texas Street car shootout at Ennis last month. He accidentally put it in 2nd instead of drive. It burned the trans out of the hole and banged the piss out of the rev limiter @ 300' mark.

wesman
04-14-2006, 01:28 AM
Also, depends on the tires/gears you're running. I was shifting into 4th with 3:73 gears and 26x16 slicks and my traps are only 115

--wes

L8 APEX
04-14-2006, 08:32 AM
My numbers were with 28's, good info Wes 26's wrap out earlier being shorter.

03LightningRocks
04-14-2006, 01:19 PM
What Terry said. Pay special attention to the issue of what will happen when bracket racing. Most guys in here could probably turn it off with no problems. As RUNVS posted, it will shift into OD at the big end if you are letting off to keep from breaking out. Then your focked...