Trans swap!

[jel111]

I have a question for the guys that have kept there inline 6. I want to keep my 230 for a while and see how the gas prices go or at least till I get a beater. I have the stock 3 on the tree and I wanted to go with an automatic. I picked up an axle with posi and a 3.90 gear. I want to go with a 700r4 as I see a lot of guys on here do. My bro says he can get a turbo 350 trans already rebuilt for bout 700 bucks. He says I should go that way anyhow. He says it won't make a diff. I say there has to be a reason all the posts I see on here go with the 700 trans. What do you all think and can I mod the old column or use one out of a newer truck that isn't so expensive as these replacement models?

[jocko]

depends what you want to do with the truck. If you will be on the highway AT ALL(!) I'd personally go with the 700. If it's just to put put around town, the 350 will be fine and save you money (in up front costs anyway). The 700 WILL save you money on gas if you get much highway time. The difference is the overdrive aspect of the 700. TH350 has 1:1 final drive, 700R4 has overdrive ratio .70:1 (or close to that). But for instance - WHATEVER your combo is (rear end, etc):

- "3rd" gear will be the same rpm in the truck with either trans.
- and whatever speed you get to on the highway that gives you 3000 rpm with the TH350, for example - that SAME speed would be achieved at only 2100 rpm with the 700 because of the .70:1 o/d ratio.

Hope that helps. There is a little more cost and a little more setup involved in the 700 - but if you will see >60 mph very much, I think it's worth it. Especially with a 3.90 rear end.

[J.Cagle]

If I guy was to put a th350 in a truck with a I6, what would be the best gear to put in it? My currently has stock rear gears( whatever that is?) I'd like to do the same as the OP. But I may end up driving soem hiway. Thanks.

[jel111]

Thanks for the reply! I will being driving the highway. I will drive this truck a lot. Prolly everyday. I am leaning toward the 700 with the more posts I read. What are the things to look for when setting this up. You mentioned that thgere is a little more set up involved with the 700 r4.

[fleetsidelarry]

Jel, more thoughts. I'm not sure what your bro was thinking, but wouldn't you rather have a 4 spd than a 3spd. the 700r is a 4 spd, the 350 isn't any different than what you have now, just more inefficient (meaning worse gas mileage.) And with the 700r, it's more than just the 4th gear OD. It's also got a great first gear. I don't know what your current 3 spd's first gear is, but the low gear in a th350 is 2.52 to one, it's 3.06 in a 700r4. that means quicker/easier acceleration off the line.

Bearing in mind that automatics are less efficient than manuals, (it takes more HP to spin them and they have slippage losses) have you considered staying with a manual? something like a t-5 from an s-10. I say this particularly because you have a six, if you had a 350 or whatever, I'd say go auto.

with a 700r, you'll be looking at a driveshaft modification cause it's longer than your 3 spd, the th350 may be the same length as what you have, don't know about the t-5. the front yoke probably has a different number of splines. you'll need a different tranny crossmember.

[samuellg1977]

Originally Posted by jel111

Thanks for the reply! I will being driving the highway. I will drive this truck a lot. Prolly everyday. I am leaning toward the 700 with the more posts I read. What are the things to look for when setting this up. You mentioned that thgere is a little more set up involved with the 700 r4.

One thing to remember is: The TV cable has to be adjusted right!! If not, you will burn up the tranny in no time flat!! With your 230 I6, you'll have to make a bracket to connect the cable. Not too hard if you can fab simple metal plates and such. The geometry on the cable has to be right. Do your research and read every piece of literature you can get your hands on BEFORE you wedge it in there. I have a 350/700R4 in my 63 Short stepper and (though it was a pain to install and setup), i absolutely will not go any other way from now on. Just the right amount of giddy up (that 1st gear is awesome!!) with gas saving and hella speed on the interstate too. The best of both worlds!!

Sam

[Crash'd Artwerks]

Originally Posted by fleetsidelarry

Bearing in mind that automatics are less efficient than manuals, (it takes more HP to spin them and they have slippage losses) have you considered staying with a manual? something like a t-5 from an s-10. I say this particularly because you have a six, if you had a 350 or whatever, I'd say go auto.

with a 700r, you'll be looking at a driveshaft modification cause it's longer than your 3 spd, the th350 may be the same length as what you have, don't know about the t-5. the front yoke probably has a different number of splines. you'll need a different tranny crossmember.

I put a T-5 out of a Camaro with an early S-10 tail housing to use a mechanical speedo cable--the original speedo cable wasnt long enough, but the bullet fit right in the hole. The S-10 trans that I had bought was out of a truck with the 2.8 V6, so it had a super low first gear--3.97:1 ! That coupled with the 3.70 gears that came in my truck would have made first gear useless. That's why I went with the Camaro trans--2.95 first gear.

The T-5 bolted right up to the original bellhousing in the original 3 speed's place. Awesome thing about that is, you don't have to make a trans crossmember ! The difference in length is 7 1/2", so obviously I had to shorten the driveshaft that amount. Luckily my dad has a lathe and I can TIG weld ! Lol ! The output shaft is the same spline count, so you can even re-use the original yoke if it's useable. I was even able to use the original pressure plate and just use the Camaro clutch disc because it is 26 spline versus the 10 spline 3 speed.

Originally Posted by J.Cagle

Would this same set up work on a newer t5 5 speed manual transmission?

You can use the early S-10 tail housing ('83-88) and use the mechanical speedo.

Originally Posted by kieth

I do not know how the T5 mounts....Kieth

It uses the same 4 bolts that the original 3 speed bolted up with. Works out perfectly because you don't have to fab a trans crossmember up.

Originally Posted by Wrenchbender Ret

No. The t-5 has a different rear houseing with the elec. drive. You would have to find a rear houseing & internal gear from a mech. drive model. They are getting scarce.

I actually found one at a local transmission shop and paid $40 for the whole thing. They bought it as a core because the internal parts were trashed. All I needed was the tail shaft and shift rail, so it worked great for me !

I have a bunch of pictures if anyone is interested.

By the way, I'm new here. Been lurking for a while. I guess I should go ahead and post my own Introduction thread.

-Aaron

[J.Cagle]

What kind of cross member would you need to add the 700r4 into one?

[Captainfab]

Any auto trans crossmember from a '63-'87 2 wd pickup or Suburban. You'll just need to drill the holes to bolt it in place in the frame.

Originally Posted by J.Cagle

What kind of cross member would you need to add the 700r4 into one?

[J.Cagle]

awesome! Sounds like its a pretty easy swap to a 700r4.

[kieth]

Originally Posted by J.Cagle

awesome! Sounds like its a pretty easy swap to a 700r4.

Here are some pictures of me adding a 350 and 700r4 to my 66

We used a tubular bolt in crossmember since it left more room for the dual exhaust later....

http://kieth.smugmug.com/Trucks/66-G...23545979_r7nUc

just click on the next thumbnail and you can see the progress ....

this shows the changes we had to make for a manual speedometer drive.

http://kieth.smugmug.com/Trucks/66-G...13173619_4TK8C

[gimmy 64]

if you are going to run the six and an auto trans you want to run the 2004r. this is because of the closer 1st and 2nd gears. the 700 has a big gap in gears from 1st to 2nd which the six does not like. go to inliners.org and they will explain it more

[fleetsidelarry]

Originally Posted by gimmy 64

if you are going to run the six and an auto trans you want to run the 2004r. this is because of the closer 1st and 2nd gears. the 700 has a big gap in gears from 1st to 2nd which the six does not like. go to inliners.org and they will explain it more

good point

[J.Cagle]

Originally Posted by kieth

this shows the changes we had to make for a manual speedometer drive.

http://kieth.smugmug.com/Trucks/66-G...13173619_4TK8C

Would this same set up work on a newer t5 5 speed manual transmission?

[kieth]

Originally Posted by J.Cagle

Would this same set up work on a newer t5 5 speed manual transmission?

I do not know how the T5 mounts....Kieth

[Wrenchbender Ret]

Originally Posted by J.Cagle

Would this same set up work on a newer t5 5 speed manual transmission?

No. The t-5 has a different rear houseing with the elec. drive. You would have to find a rear houseing & internal gear from a mech. drive model. They are getting scarce.

[J.Cagle]

pm sent Crash'd!