Chevy & GMC Vans

Turbo 350 in an astro? I am having transmission problems with my 700r4. I thought rather than having it rebuilt for $1700 I could buy a new 350 from summit for around $700. I dont need the OD. From what I understand the 350 is the same size as the 700r4. Would I have to build custom tranny mounts? I would probably buy a floor mount shifter, so the column linkage wouldn'd be an issue. What am I overlooking? I this as simple I think it is? Will the stock driveshaft work?

I am pretty sure the 700R4 is longer, wich would mean you need to get your driveshaft shortened... but I would double check that as I am not 100% sure... other than that you wont have any problems, the column shift will work, it will just stop at 2 and not go into the 1 position.

Hi Zach,
Consider rebuilding your tranny.$1700 sounds on the high side.With the right parts for the rebuild you can make your trans all that 350 and more.Where you located?.Look for a private owned trans shop that has been in business for a long time.Shop it around for a better price.Tell us what is wrong with your trans.There are many,many members here that can suggest how to make your trans live a long,long,time.Swaps generally look cheaper at the beginning and can end-up costing more than fixing the OEM trans.Valve body mods done by a lot of members is a Trans-go kit,Vett servo,.5 boost valve,trans cooler.

I am in Houston TX, I called a known tranny shop here that does alot of performance builds. I told them I wanted my transmission to be good for up to about 400hp. I figured that since my transmission is messing up, now would be the time to put something better in so I dont have to worrie about it when I drop a v8 in it.

Now the symptoms...

When I just start my van and it is cold, I have to rev it high or it will just sit there slipping.

when I am driving it sometime it bucks hard. This has happened at all different speeds, and even sometimes it will stall my van.


so there it is.... any suggestions?

You will need to fabricate on the mount of the cross member, but other than that a 9" tail shaft TH-350 will fit, the difference in overall length is something like 1/16 or 1/32 an inch nothing to worry about with a slip yoke. For 1700 it'd better be 400hp capable, nationa average for a stock 700R4 is something around 1175. That being said a 4 speed slush box carries a premium for the rebuild you're talking significantly under 600 bucks for the whole mess in parts.

I paid $800.00 on my 1994 Lt when I bought it with a blown tranny.That was R&R&R from a friend who owns a trans shop.

GEJ wrote:I paid $800.00 on my 1994 Lt when I bought it with a blown tranny.That was R&R&R from a friend who owns a trans shop.

actually a very good price he cut you a pretty big deal.

Yep

Mr_Roboto wrote:

GEJ wrote:I paid $800.00 on my 1994 Lt when I bought it with a blown tranny.That was R&R&R from a friend who owns a trans shop.

actually a very good price he cut you a pretty big deal.

Don't complicate your life any more than it needs to be. If you always dreamed of a 3-speed Turbo Hydramatic transmission, then that's different (though your dreams could use a little more excitement ).
But if you're doing this to save money & hassles, I don't think it's worth it. Find another 700 in good shape and run it as is if you're tight fer bucks. Or, get yourself a 700 tranny from PATC, they offer 3 or 4 different levels of wickedness.
As well, you might not think you need an overdirve now, but slap in some 3.73's or 4.11's gears and mebbe high(er) stall converter and you might just regret going the antiquated 3-speed way.

Listen to these guys. Turbo 350 is a dinosaur. The newest version of the 700R4 is actually a 4L60. 1988 to 1993. It has 30 splines on the input shaft. And other good upgrades. and can be made to handle serious HP. It's also a direct bolt in swap.

I dunno, I am far more of the opinion the 350 is fine, but you have to stay within its strengths. If you do a lot of out of town driving or if you do a lot of city driving, wether or not this is a weekend vehicle or a daily driver all come into play. For a "weekend" van that sees limited milage on the highway, a TH-350 is not only good but great. It has advantages over a 700R4 such as being significantly lighter, a way better 1-2 ratio (a flaw with the 700R4 IMO) and can be made durable for much cheaper if you are paying for the labor. That being said, I can tell you how to build one up for under $700 including the cost of tools if you are inclined to do so and probably way less. I've decided my van will probably eventually be power glide or TH400, but they both require some fairly extensive modifications to fit. Seriously leaning towards the glide right now but only if the torque is high enough.

Here's a guy that shows being registered on Ebay since 07 but think he was in Fl. long before this and was registered then so don't know what that's all about. Think this may be where Trybe got his 700r. Not sure of that but anyway,,check out his different builds and prices. This will give you an idea of what's out there and the price range. Watch for core charges and shipping. I'm not saying contact this guy, it's just a suggestion on something to compare to.
Check with James and see if this is the guy. He got some great service and a few issues the guy was all over making it right.

http://motors.search.ebay.com/_W0QQsassZoutlawtranny