4.10's and 35's with overdrive

[andyblack]

Hey, I just saw this thread. One thing I'd like to add is that you can possibly go to a torque converter with a different stall speed to keep the tranny from hunting gears all the time. I know my swb pickup is much lighter than what you have, but I have a 700R4, 35s and a 305 that's stock and the only time I have a problem with it downshifting a lot is when I try to use the cruise control (yes it still works) on an interstate with a lot of hills. The thing is, I don't think the torque converter is locking up fully. That may be why the truck doesn't feel as weak as most 305 trucks I've encountered. It also only gets 10 mpg though. I don't know what stall speed the torque converter is, but you may want to look at that.

 

[G-Force8]

Hey, I just saw this thread. One thing I'd like to add is that you can possibly go to a torque converter with a different stall speed to keep the tranny from hunting gears all the time. I know my swb pickup is much lighter than what you have, but I have a 700R4, 35s and a 305 that's stock and the only time I have a problem with it downshifting a lot is when I try to use the cruise control (yes it still works) on an interstate with a lot of hills. The thing is, I don't think the torque converter is locking up fully. That may be why the truck doesn't feel as weak as most 305 trucks I've encountered. It also only gets 10 mpg though. I don't know what stall speed the torque converter is, but you may want to look at that.

thats an idea. Thing is, I plan on replacing the stock GMPP 700R4 with a BTO stage II unit and I'll be considering torque converter options at that time, which will be around the time I swap in a Dana60 front,more lift, and regear for 38.5" swampers

 

[cuervo]

www.diy4x.com has a gearing calculator under tech tips.

at 75 mph you would be turning 2070 rpm in od.

in drive you would be turning 2970 rpm to go 75.

What is the trick to get this thing to work? I keep getting error 13 and it crashes.

 

[cuervo]

NVM, I found one online.

With 4:56 315/75/17(35s I believe) and a .75 on a 4l804 it looks like I'll be at 2250 RPMs when doing 75.

I used http://www.kabamus.com/garage/gears.html#gearspeeddata

I should have about 385lbs of TQ at that RPM so I'm feeling pretty good.

 

[andyblack]

I forgot to mention that with my 305/700/4.10s, my overdrive kicks in at about 50 mph most of the time. As long as I don't use the cruise control on the big hills and anticipate when I need to get on the gas, the trans doesn't hunt gears at all.

 

[Blue85]

Hey, I just saw this thread. One thing I'd like to add is that you can possibly go to a torque converter with a different stall speed to keep the tranny from hunting gears all the time.

I don't know about this. I would only match the stall speed to the cam and intake being used. Even small increases in rated stall speed can really suck in a heavy truck. Plus, the higher the slip, the greater the heat, turning a borderline tranny situation into a real problem. Make sure the clutch locks in overdrive!

 

[andyblack]

I don't know about this. I would only match the stall speed to the cam and intake being used. Even small increases in rated stall speed can really suck in a heavy truck. Plus, the higher the slip, the greater the heat, turning a borderline tranny situation into a real problem. Make sure the clutch locks in overdrive!

Good advice. I've never really messed around with different torque converter stall speeds but I've heard about people changing them and it making a difference. Automatics are still kind of weird to me at this point. The truck I have now is actually the first vehicle I've ever had with an auto.