Okay I'm new to the OD Trannies ,and I'm unsure of which T/C to use . I've seen both ,the locking & Non-Locking . Can someone Coach me on the finer points of the Right T/C for my application . Eventually I'll have A Posi with 3.55/3.73's (leaning more towards 3.73) , 235/60x15's ,1970 350 GS "SP" Coded , Larger Cam (?sorry haven't gotten that far) , Hotter Ignition , 2.5" Duals w/X-Pipe, It'll be mostly a Cruiser . Also , How can I find the Cruising RPM range @ 70 mph. with the 3.73's & 235/60x15's . I know I used to have the site but can't find it . Thanks in advance . Steve
Steve, your combo sounds very close to mine. I chose to go with the "9x11" converter. I like the lockup because you can have it stalled for max performance (4000 in my case) with a larger cam, but lock it up for highway driving. The milder the cam you run, probably the less benefit you will get from a lockup.
I use a "D5" from http://www.ckperformance.com/gm_200R4_convert.html like the lockup for the highway. This is with a built up 455. I use a 3:73 with 275/60/15's. The lockup has a manual switch and it is like having a 5th gear on the highway.
I chose the lock-up converter also. I put a toggle switch in my glove box to control it. If I'm just cruising around town, I leave it off. But as soon as I'm getting on the highway, I flick it on and it's great. The only time it can be irritating is if you leave it on and at about 43 mph it engages. Now your engine is loafing along at about 1200 rpm's. I run a 3.73 gear with a 28" tall tire. 70 mph is about 2200 rpm's cruising down the road in lock-up. Can you say nice!! :TU:
Sounds great ! I have a Crower Cam #50259 that is a Perf. Level 4 (5 being most radical ) . 284/290 Adv. Dur . / @ .050" 226/234 , I-.499" / E-.508" . The worst part is gearing , it's a 2.78 . And a Posi. 3.55/3/73 is a while off unless one drops from the sky . Is there any way I can run that cam for the time being using a higher stall (2200-2500rpm) , and perhaps "Rhodes Lifters"? Off Idle wouldn't make the cam seem smaller to the engine ? The one thing for certain , The car will be seeing alot of Hiway Time 65/70+ Cruising . How would it fare with those 2.78's /.67:1 ratio and the 235/60-15 ? Would I be lugging the engine ?
using the calculators on this page... http://www.tciauto.com/tech_info/calculators.htm at 55 MPH 2004R Locked converter 1324 RPM at 70 MPH 2004R Locked converter 1686 RPM I'd say thats lugging the engine, especially when it has a cam designed for peak torque at a higher RPM. If the engine was designed to have good torque at 1700 RPM it would work. You could always run the 2004r in 3rd gear until you installed the 3.73's It acts just like a 3 speed in 3rd.
To make this work you should leave the engine mods to being the LAST thing you do. Get the suspension, brakes, trans, rear end done first. Converting to a 200r4 is not an inexpensive undertaking. You should probably check out Phil's thread on doing this. There are a lot of little things that are vital that you must plan for. To run the current gear you have with a 200r4 you will need a high stall converter and will have a lot of heat. That means you MUST have additional cooling with the trans (good idea anyway.) Since your planning on a cruiser you will not want to run a motor that needs a 4000 rpm converter. Plan on building a motor that needs about 2500 stall and you will get good all around performance. Set up a plan for your upgrade with priorities and follow it. Good Luck!
