Another 235 with open driveline question...

I am planning on in the future switching to an open driveline in 54' Belair. However I would still like to retain my factory 235. In the near future I plan on adding some headers and dual intake. Its a PG car with 3:55 gears.

I have a couple questions...

1) I would like to retain an auto transmission...700r4 or 200r4? Where I'm at it seems like I can pick up a 700r4 alot faster and easier than a 200r4.

2) Does either transmission allow for the use of the stock speedo cable? I would really like to retain my stock gauges.

3) Lastly, what rear axle gear ration would work best in my set up? I want to be able to cruise nicely around 70 to 75mph on the highway.

Looking for ideas or opinions from anyone out there who has or had a similar set up...pro vs. cons...and such

 

I used a T-5 in my 50 with 261 engine and 205-75R15tires and liked the 3.36 gears best after trying 3.55 and 3.78 first should be the same for either a 700r4 or 2004r although I tended to drive in 4th up to about 60-65.

 

1- You will need to pick up from Tom langdon a tranny adapter plate
2- I believe the speedo cable will fit but not 100%
3- I'm using a rear out of a S-10 blazer 4x4 with 3:42 gears 59.5 inches outside drum to drum fits nice.

 

700R4s used mechanical speedometer cables through '90 or '91.

 

I came across a 55' Chevy Belair rear end, 3.70 gear ratio. Anyone use this with a AOD like a 700r4 behind a 235? Is that a good gear setup?

 

I don't think you would get much benefit from those gears.

 

With a 30 percent overdrive, 3.70 turns into 2.59 in o/d.

 

You will want to turn around 2200rpms @ 65mph with a 235. Go to an online gear calculator and plug in the numbers. Done.

both transmissions were available with cable drive. Look before buying.

'86 and Earlier 700-R4's are not as durable as the later ones, but they can be upgraded. Keep that in mind when buying one.

Because of the difference in 1st and 5th between the 700-R4 and 200-4R, sometimes one is a better choice than the other. Depends on cam profile and how you plan on using it. A stock 235 will work fine with either one.

 

Thanks snarl, looks like a 3.70 or a 3.73...would work at a .70, a final .67 on the 200r4 will bring me closer to 70mph @2200. Which is still okay.

Does the rear axle matter if it came off a manual or auto car? I wouldn't think so, just thought I would ask.

Again, I am mainly looking to cruise at a decent highway speed, not trying to whoop anyone off the line.

I am add a 3/4 cam down the road when I have the motor gone through..but for now some headers and maybe a dual carb intake. keep it simple.

 

i would look for a 3.42 gear rear end for a manual car or 3.73 for automatic. the rear end does'nt matter if it came out of car or truck ,manual or automatic . it just matters what gear you want.

 

Start planing ahead for the correct tv cable hook up. It needs to be right. Not sure how you will do that with a pair of carbs on the 253.

 

325w...educate me...what exactly do you mean? thx

 

+1 on this, if you don't have your TV (trottle valve) cable hooked-up correctly and adjusted correctly your tranny will shift all funky and will eventually burn up. In it's simplest form, the TV cable tells the tranny where the throttle is positioned so it knows how to shift.

When attaching it to your carb linkage you have to be aware the linkage geometry and how far away it's attached from the linkage pivot. Attaching it too close the cable will open slowly and not fully when at WOT (wide open throttle). The reverse is true, if too far away the cable will open too fast and will make the tranny think its at WOT when it may only be 3/4 of the way there. Some internet research and a trip to a juckyard to study the linkage geometery and you'll get it all figured out. Besides, you're going to want to grab some parts such as the mounding braked for the TV cable at the carb end.

Adjusting the cable it's self is really easy. Check out this link for adjustment along with a much better description of operation and issues when dealing with non-factory linkage.

http://www.cpttransmission.com/tech_tvcable.htm

One more thing to think about is the TCC (torque converter clutch) lock-up. You can buy lock-up kits but all you need are a few robbed parts at a junk yard, or just get some fresh ones at the parts store. You can go an even easier route and install a simple toggle switch for the TCC, just don't forget to throw it when comming to a stop.

 

Thanks for the info Hussey. Unfortunatley I am not that savy...I will probabley have a shop do the whole conversion to open driveline for me. A) I don't nearly have the space I would like to do it myself (living in a cookie cutter home, small garage and crazy HOA). B) i love doing research and figuring out how to build and make things work on my own..but this will be a better task handle by someone with know-how..

I might set up the rear end myself...but thats about it...

How about a 350 auto setup, is that worth looking into?

 

A 350 doesnt have OD so you wont get that highway speed rpm reduction.

 

So I am planning on picking up the 3.70 rear end out of that 55' chevy...can I also use the drive shaft out of the 55' as well to mesh to the 700r4?

 

not as is. The length is probably wrong and the yoke is the wrong spline. It is probably too long, which is beter than too short, just take it to a driveshaft place and have them shorten it and change the yoke and put in new U-joints and balance it.....
Or leave it till last and let the shop that is doing all the work for you worry about it...