Bolt on Overdrive

[USMCBLB125]

I was looking into the Gear Vendors under/overdrive unit, and I've seen other members mention it on here, but are there any other quality kits anyone is aware of. I don't necessarily need an overdrive unit rated up to 1250 HP I'm looking closer to 600-650.

[monte70car]

Burton your other option is a 700r4 or a 200r4 built for that hp range. The 700r4 and 200r4 will replace your current trans rather it be a 350th or 400th. As far as bolting straight up to the back of a trans Gear Vendors is probably only thing on the market.

[Winston Wolf]

I never liked the way high stall converters drive. Mushy pedal and it just seems like there is no throttle response. You are not really going to save any money with a GV either. I just can't see their logic of cruising way below the stall speed without a lock up converter....

[USMCBLB125]

I guess I was a little ambiguous, and I hadn't considered everything you had mentioned Allan. I basically want a quick cruiser. I may bring it to the track every now and then on test'n'tune days for kicks but I don't have any plans to race competitively. My goals are a 454 with 500-600 HP TH400 trans, and probably a 3.73 gear. I'd like to end up with mid to low 12's in the 1/4.

 

I Suppose this has strayed a little from my original topic buy I'm interested in what some of you think is the best way to approach this set up. Thanks for all of the advice already.

[USMCBLB125]

Hmmm. I hadn't really considered a 700R4. I've heard they were too expensive to build, and withstand substantive HP, compartively to a 350 or 400. And I have a bit of a speed streak and I don't know that I'd be happy with 5-600 HP

[monte70car]

here is a good place to shop for a 700r4 http://www.bowtieoverdrives.com/catalog/catalog.php?Action=GETSUBCAT&CATID=B they also sale 200r4 and 4l80e, for above 500hp they call for the 4l80e to be used.

[USMCBLB125]

Thanks Rob, I'll check them out

[Winston Wolf]

If you have low gears, I would go with a 200-4R. It's also a bit simpler swap than a 700 if you're coming from a TH350. Cost is a wash if you count in the driveshaft shortening you will need with the 700R4.

[Winston Wolf]

I won't disagree that it would be a smart update on the u-joints, but don't think it's absolutely necessary though. If he only wants to run 12's in the quarter, there's no need for 500+ HP either. 450 should get that done pretty easy. One thing to consider is a roll cage at 11.99. They won't let us run around here at that speed without one anyways.

[Winston Wolf]

Yeah. I think that driveshaft loop is required already in the 13.5 sec range.... I just fab'd my own with 1/4" flat stock and 4 bolts, but I see there are many kits available.

[kc8oye]

i run a mildly built 700r4 with 3.55 gears, and even with only 325-350ish hp 355cid engine, my car is MIGHTY quick around town. and by mighty quick, i mean that with the exception of corvettes, and other extensively modified perforamnce cars (f-body's mustangs etc) there are pretty much no production cars that can touch me in a 'stop light' drag race

 

I run a 2500 stall converter that's a tad high for my combo right now but i'm going to add more cam and heads soon

around town, I pretty much never lock the converter up. (I installed a nice large stand-alone trans cooler too)

and it's low enough stall that I don't really notice it. it also helps that I have a 'tight' converter.. at light throttle it behaves more or less like standard production converter.. but when I whack the throttle open the engine spools up to aroudn 2500 and then promptly breaks the tires loose :>

 

when I hit the switch to active the lockup converter, I run 2250 rpm @ 70mph with 3.55's and 255/60-15 tires (27" tall)

 

overall it's a fantastic combo. that low 1st gear makes for an impressive 0-60 time in a car that weighs 4,020lbs with me and and 16 gallons of fuel.

 

i run the 1/8 mile in a hair over 9 seconds @ 87mph so I figure my 0-60 time is around 7.5 to 8 seconds.

 

i don't have enough cam to run good 1/4 mile times tho

14.243 @ 95.95 mph is my newest 'best'

 

[BuffaloBillPatri]

I copied this about a year ago, don't remember where.

 

"Can I run a high stall converter in overdrive with a 3.42 axle?

 

Yes, this is one of the most often confused questions (even when you ask people you would think would be knowledgeable). Here is the detail. Our example could be this 3.42 Chevy guy. In overdrive he is going to be a 2.67 final drive ratio. He is a Cutlass body with 27 inch tire and so at 75mph in overdrive the motor will be turning 2484 rpm and he has a 3500 stall speed on the back of a pretty nicely built 350ci motor making close to 400hp. 95% of the people you would ask (even tranny guys) would say no-way and yet we know this is an awesome package (drives wonderful, no high temps in the trans etc) why does it work? When his converter was made it was set up to stall at 3500 with 400hp. However if you put 600hp to it it would stall at something like 4500. Conversely if you only put 125hp to it (as when you are just crusing at 75mph not accelerating) then the stall is way down at 2,000 rpm. So his stall with a 3500 converter is not 3500 at cruise because

he is not making 400hp. Car drives wonderful. If he romps on it while cruising then the trans is going to downshift to a lower gear and get him into the powerband. (note: read gear vendors passing gear in this section) So, this is why you never lie to you converter builder (because if you overstate your hp you will not get the stall you wanted).

 

The package of 3500 and 3.42 with 400hp is a sweet setup with a GEAR VENDORS . Without a GEAR VENDORS the trans will not have a great passing gear because 2nd is too low. But with a GEAR VENDORS it will jump right into 2nd-over which will rip nicely and put the converter right in the power. You can use this setup as a guidline and say move up or down in ratio related to stall from this good setup with a GEAR VENDORS."