Over and Under for an auto???

[justinp20012500]

Does anyone have any suggestions for a under/overdrive for a 47RE. When I am manually locked up in OD my truck only goes 111 MPH. NOT FAST ENOUGH!!! O ya, and I have 265 x 70 x 17 Michelins

 

[Chipstien]

Dump the 4. 10 gears for either 3. 73 or 3. 55 gears if you want to go faster. Around here in the PNW, you will have pushed about 50 cars by the time you reach 90... ... .

 

[Chipstien]

Oh yeah, US Gear and Gear Vendors are two companies that make over/under drives.

 

[justinp20012500]

O ya, I forgot to list i have a Dana 70 with a factory Limited Slip loaded with 3. 55's

 

[Snow man]

you need to cut an orange wire under the hood above the valve cover. This is the speed limiter wire. With that wire cut the truck should do well over 125mph if it has 3. 54's.

 

[justinp20012500]

Originally posted by Snow man

you need to cut an orange wire under the hood above the valve cover. This is the speed limiter wire. With that wire cut the truck should do well over 125mph if it has 3. 54's.

Thanks SM, but I govern out (my tack won't go any more). I dont think that is right having 3. 55. ????

 

[Snow man]

mine with 4. 10s hits an indicated 111-113 on the speedo,at 3550RPM. my dads early 01 ive had to 125 and it had more in it,he has 3. 55's.

Maybe you have 4. 10's?

 

[justinp20012500]

Nope, I put chrome diff covers on, and the tag on it said 3. 55??? Could something be wrong in the transmission?? I used a GPS to get the speed, so for what I know its right!?

 

[Spooled-up]

Mount some bigger rubber! That'll help a little and it's probably the cheap way to go.

 

[Chipstien]

According to a speed calculator you should be at 111 MPH at 2900 RPM's and 127 at 3300 RPM's. Are you sure the TC is locking up? My truck with 4. 10's and 315 tires does 120 MPH at 3300 RPM's but I am able to take it a little beyond 3300 so therefore top speed is even higher.



If you put 315 70 r17's on your truck then you would have the capability to go 138 MPH at 3300 RPM's. Is that fast enough for you?

 

[justinp20012500]

Originally posted by Chipstien

According to a speed calculator you should be at 111 MPH at 2900 RPM's and 127 at 3300 RPM's. Are you sure the TC is locking up? My truck with 4. 10's and 315 tires does 120 MPH at 3300 RPM's but I am able to take it a little beyond 3300 so therefore top speed is even higher.



If you put 315 70 r17's on your truck then you would have the capability to go 138 MPH at 3300 RPM's. Is that fast enough for you?

Where did you find the speed calculator?? My truck dynos @ 417 Hp and 1019 ft/lbs, so i know the converter is locked. I wouldn't be able to get numbers like that it if it wasn't.

 

[Snow man]

My trucks power peaks at 106MPH on the dyno,and it goes 114-117 on the dyno depending on hwo long i let it wind out. And this is with 4. 10 and 285 tires, RPMS are Approx 3500. The speedometer on the dyno Jet is dead on,so somethings amiss.

 

[Chipstien]

Originally posted by justinp20012500

Where did you find the speed calculator?? My truck dynos @ 417 Hp and 1019 ft/lbs, so i know the converter is locked. I wouldn't be able to get numbers like that it if it wasn't.

Here you go! http://www.klenger.net/dodge/general-reference/gear-speed-calculator.xls You can thank fellow member klenger for this great calculator.



I agree with Snow that something doesn't seem right. Has your speedo been re-calibrated for the new tires.

 

[justinp20012500]

I went and played a little at lunch, and here is what I found...



1200 RPM's Locked up it went 46. 5 MPH

2200 RPM's Locked up it went 85 MPH





From what that speed calculator says, I am right on. I guess I am just running out of road.

 

[Mad Bomber]

Originally posted by Chipstien

Oh yeah, US Gear and Gear Vendors are two companies that make over/under drives.

From what I've heard they DONT stand up to more HP in our trucks. At least 2 people in our club NW Bombers have had or have worked on them they BOTH said the are a POS