Always race with O/D off?

BigNutt · Jul 25, 2005

I went o the dyno the other day and they of course had to dyno me in Drive with the overdrive off, 3rd gear. Anyways I have never been to the track, but have raced a few times and never once thought to take the car out of overdrive. I understand when the auto tranny switches into overdrive that is a weak spot in the tranny, but if your racing to 100mph+ you can't really be doing the car any better by being out of overdrive can you?

I'm just wondering when you race with overdrive on and when you race with it off? If there is a chance in it being damaged going WOT on a dyno, I assume it would be a bigger risk on the ground.

TGJ · Jul 26, 2005

I know of quite a few broken 4R70W transmissions that broke because of a WOT 3 - 4( OD ) Shift. Some of them were quality built transmissions too. You may get away with it a few times but do you really want to chance it? Better to be safe than sorry and turn the OD off.

BigNutt · Jul 26, 2005

Okay, but how does being in regular drive affect rpms when racing at high speeds? I have 4.10s and my O/D kicks in at like 90 mph, but I am thinking I need 3.55s if I do any racing much over 100mph with O/D off right?

TGJ · Jul 26, 2005

You would be better off keeping the car out of OD while racing. At higher speeds the car will be in it's power band while in 3rd. If you are concerned about fuel mileage at those higher speeds, well then being in OD may be ok, but you want to avoid WOT shifts between 3 and OD. You should be ok with 4.10's.

BigNutt · Jul 26, 2005

TGJ said:
You would be better off keeping the car out of OD while racing. At higher speeds the car will be in it's power band while in 3rd. If you are concerned about fuel mileage at those higher speeds, well then being in OD may be ok, but you want to avoid WOT shifts between 3 and OD. You should be ok with 4.10's.

Just wondering cause when I am just cruising I m at 4k rpms at 100mph. 4.10s + S-Trim = high rpms.

ProCharger GT · Jul 26, 2005

i've never had any problems at WOT in OD going from 3-4

03ghoststang · Jul 26, 2005

i've never had problems shifting from 3-4 at WOT with (OD) off and manually engaging it or with it on.

03ghoststang · Jul 26, 2005

BigNutt said:
Just wondering cause when I am just cruising I m at 4k rpms at 100mph. 4.10s + S-Trim = high rpms.

3.73's will do the trick for a supercarged applicationand the rpm's arent that high as 4.10's

tomustang · Jul 26, 2005

YOu should have the OD OFF all the time until you use it or run out of rpms in 3rd.

1ba96gt · Jul 26, 2005

03ghoststang said:
i've never had problems shifting from 3-4 at WOT with (OD) off and manually engaging it or with it on.

How would you manually shift into 4th? Its 1,2,D on the shifter. Why you you want to go to 4th, your idle set up is to stay in 3rd till the end of the track. I do it with 4.10's+S Trim with 26" tires. I am pretty sure I trapped 123mph at about 6300 rpms (trying to remember).

streetstang03 · Jul 26, 2005

you must of had some serious mods to trap 123mph

BigNutt · Jul 26, 2005

tomustang said:
YOu should have the OD OFF all the time until you use it or run out of rpms in 3rd.

I don't see why you say that, I hardly ever boost and my 25 mile comute to work is all hwy. I see no reason to even have it in drive until I 1. dyno or 2. race.

1ba96gt · Jul 26, 2005

streetstang03 said:
you must of had some serious mods to trap 123mph

Yup, I do. Everyone gets a laugh when I ask them to race my 96 GT with a slowmatic and side exhaust that cost me at least 20rwhp according to everyone else. The beauty of the sleeper. No but really its a very modified daily driver.

streetstang03 · Jul 26, 2005

mods?

1ba96gt · Jul 26, 2005

BigNutt said:
I don't see why you say that, I hardly ever boost and my 25 mile comute to work is all hwy. I see no reason to even have it in drive until I 1. dyno or 2. race.

I think thats what they meant. Your original question was about dynoing, and mentioned racing thought. There isn't a reason to turn it off on normal driving, then again I don't do 100+ WOT in normal driving.

The for turning it off on the dyno is to get a 1:1 gearing. Car must have that on the dyno for accurate results, so you don't want the car to shift or you'll get false numbers.

1ba96gt · Jul 26, 2005

streetstang03 said:
mods?

An S Trim (unintercooled at the time) 4.10s, e.t. streets and most of the other fun stuff. Nothing crazy or out of the norm as far as cams, and boost levels. A much simplier set up than most people expect.

streetstang03 · Jul 26, 2005

and you're trapping 123mph?

what did you dyno?

1ba96gt · Jul 26, 2005

streetstang03 said:
and you're trapping 123mph?

what did you dyno?

494rwhp 440rwtq std to answer you question. And please don't start an arguement on my set up being capable or not, it won't help the thread any.

streetstang03 · Jul 26, 2005

im not trying to start an argument....can you give a full mod list?

2001sleeper · Jul 26, 2005

streetstang03 said:
im not trying to start an argument....can you give a full mod list?

+1

Always race with O/D off?

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