Driveline project

by Biomedtech Fri Apr 08, 2011 9:50 am

OK, I'm on to planning out the drivetrain for the 76 guna,

I'm planning on putting in around a 400hp small block backed by a Monster kit installed 700r4. My question is if I'm running 315/35r20 nittos on the rear what rear gear should I use to get approx 2000rpm at 70 mph? Also should I consider a different TC and if so what size/stall should I go with?

Just for street cruising, no strip time planned for now.

by JB2wheeler Fri Apr 08, 2011 12:09 pm

Not doing the math and just taking a wild guess, I would say the stock ratio should do it. I'll let one of these college kids on here do the math. JB

by The Dude Fri Apr 08, 2011 1:41 pm

315/35r20 tires = 28.7" diameter
700r4 OD = .7

With those tires & that OD ratio, 3.42 gears will put you at 2000rpm at 71 mph assuming the trans is in lock up mode.

Can't recommend a torque converter without knowing engine specs, but your best bet is to ask Monster transmissions what they suggest since you are using their stuff.

by pila Fri Apr 08, 2011 2:14 pm

It's always better to ask the folks who are into it, like the trans guys. Talking to companies on their tech line can save a lot of bucks and work sometimes......

by The Dude Fri Apr 08, 2011 2:18 pm

Yep. Too many variables including driving style, weight, torque curve, & vehicle use to try & suggest a TC. Not to mention cam specs, gear ratio, whether or not you have a separate cooler, etc.

by JB2wheeler Fri Apr 08, 2011 5:41 pm

I have 3.42 rear gears with a 1 to1 final ratio (TH400) and a 27.1 inch tire and I run 3,000 rpm at 62 MPH. I am running a 2100 stall converter now, but at first I was running a 2800 stall and it did not like street driving at all. JB

by 74Malibu383 Tue Apr 12, 2011 1:25 pm

I'm running the same tires and same transmission. With a 4.10 gear I'm running about 2500 at 70mph. Rago's math works out though.

FYI - A 4.10 gear with the 700's low 1st gear is a little much. I plan on going down to a 3.42 or so before the next LONG road trip.

Also, the torque converter won't matter in regards to the cruising RPM. It'll lock up if you have it wired correctly.

Food for thought - I have a 2800 stall.

by Biomedtech Tue Apr 12, 2011 10:20 pm

74Malibu383 wrote:

Also, the torque converter won't matter in regards to the cruising RPM. It'll lock up if you have it wired correctly.

Food for thought - I have a 2800 stall.

Which brings up the next question, I was at a swap meet recently and there was a guy selling 700r4's that he states are wired internally for the lockup. All that is required is one 12V wire to the trans. Is this accurate? I thought I was going to have to buy a magic box from TCI or the like...

by pila Wed Apr 13, 2011 12:16 am

A friend has a couple 700R4s in his cars, and he said something about an item used in diesel engined cars with a 700, that he uses. Don't know the details. I'll have to ask him about that, since the question comes now & then.

by 74Malibu383 Wed Apr 13, 2011 11:17 am

Check out this link. It took me all of 5 minutes to wire this thing in. It just replaces your current brake switch.

http://www.bowtieoverdrives.com/catalog/catalog_inc/viewitem.php?ITEMID=334

This kit is used in GM applications that have a stock plunger style brake switch and doesn't have cruise control. This kit was designed to lock up the torque converter without the need of a computer. We prewire all of our transmissions with an internal wiring harness prior to shipping out our transmission. This kit will complete the lock up system of the torque converter, which will automatically lock up in fourth gear, and give you the capability to manually lock up the torque converter in second and third gear also (typically for towing applications). This kit comes with a new AC Delco brake switch, weather tight pigtail and every accessory that you'll need to install it.

by Pdawgie Wed Apr 13, 2011 2:45 pm

You can also rewire it and have the lockup on a toggle switch. (AKA: 1 wire), that's how I have mine hooked up. I just told the tranny shop that I was doing it this way, and they did the wiring inside the tranny, I had to just put in the toggle switch.

by 74Malibu383 Wed Apr 13, 2011 3:52 pm

Correct. Or you can wire it so that both methods work. The brake switch does it automatically, or if you want, you can flip the switch and lock up the converter at any time.

by Sponsored content

Driveline project

Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project

Re: Driveline project