Since I am restoring my 77 cutlass supreme brougham. We are playing with the engine, sounds like we are building a stroker 380 around 425 HP, getting rid of the 2 something rear end and putting in 3.42. Now should I bother to put in an 3 speed tran with over drive or just leave the th350 in it. Is there any mod's to do if we put a 3 with overdrive? Also put in a shift kit and stall converter?

 

Well, if you do a lot of freeway driving you may see a benifit. But if I remember right the TH200R has a .67 in overdrive. If that's right, then the final drive ratio with 3.42 gears would be about a 2.12. If you decide to go with an overdrive you may want rear end gears more like the 3.91 to give you a final drive ratio of 2.42 which is still pretty tall. I had a 1976 Cutlass years ago with 2.41 gears and it wasn't bad on the highway. My 2 cents worth. John

 

What kind of RPM would it run at 30 and 60 mile an hour if we went with 3.91, to me seems low ,no? My trucks both have 3.73, to me that is low enough. TH200r hard to come by? any mods to the car if I went with this

 

What would mileage be at, around 18. My 07 duramax 366HP and 650 torque gets around 18. Has 3.73 gears but also 6 speed ali in it would it compare?

 

what about posi. worth it?

 

Unless a 200r4 is heavily modified, it won't last with the torque of an Olds!
A 700, with an adapter, woudn't need that much modification to last.
1st gear, [3:06] woud get you out of the gates better, and the O.D. is still there!
3:06 x 3:42 = 10.53
2:52 x 3:42 = 8.64
Some say the RPM drop from 1st to 2nd is accessive, but with the torque of an Olds, you'll be fine!
Mods include moving the crossmember back, shortening the driveshaft, a switch for the O.D. and lockup, and TV cable linkage - all available aftermarket!
To me, posi is a must! One-leggers'll only burn up a tire at a time - both look and feel better!

 

Bear with me, x your ratio's 10.53/8.64 what is that mean? What is the easiest approach for this procedure.Bolt tran to engine,place engine,block up tran,put cross member into place.Then you can get your shaft measurement?Are the trans easy to come by, what about stall converter/shift kit?

 

The numbers are your 1st gear ratio x rear end ratio - the higher the better!
3:06 is the 700 - other is a 200.
I like to do the engine and trans seperatly - PIA together, unless you've a lot of room, and an excellent engine hoist.
Everythings available mailorder - uness you've friends at a trans shop.

 

Found this web site www.BowtieOverdrives.com but they call it 700R4 same thing. Where would be the best place to buy

 

Yeah, that'll work! Just make sure you tell them you need the Olds adapter!
Call them tomorrow -

 

I would look at a art carr california performance transmition 200r4
you will have plenty of low gear with 390's way to much if it is not posi . Will have better gear spaceing for it up shifts closer ratio's and a taller od you will have to spend money on both a 700 and a 200 . Other wise look into a gear vendor, expensive but no tv cable to adjust and can be driver shifted if wanted or on board computer comes with . The gear vendor is about 2500 and a 200 or 700 will be about 1900 from what i have seen form cpt or tci.

 

My 91' Safari had 4.10 gear with 215/78R/15. There was no problem with RPM when I went on trips. Don't be afraid of a bit of gear.

 

Sorry but what is a gear vendor?

 

A seperate unit that bolts on the back of your exhisting trans - about 100 lbs.
Check it out on the web!

 

thanks for the info

 

Jmo but I have a 200-4R with lockup along with a 3.73. Personally I'd go with a 3.55 or even a 3.42 next time. Remember you can choose to not engage the overdrive until higher rpms and on top of that the lockup won't engage until you're in 4th. That sounds like alot of options to me.

Plus they have more evenly spaced ratios, 2.70, 1.52, 1.00, .67. On another note, 200-4R's are powering 9 second 20psi turbo'd GN's making 600+lbft of torque. If built right they're as bullet proof as anything else.

 

yep we are going this route

 

2000 rpm with a 3.42 gear, 2004r and a 25.5" tire. Get one built by someone who knows them. Mine shifts great but getting the shift points on my low po unit is a pain.

 

Got a hold of bowtie overdrive, they are setting me up a price, going to a level 3 200r4, couple of upgrades I can do to it. They figure I will need a 2500 to 2800 stall converter put in as well