need opinions on keeping my 350 tranny or switching

[rome704]

Well when i bought ((boomer)) the truck it had a 350ci/350 transmission with a Hurst shifter...it shifts fine but i need more gears on the highway its screaming and the revs are to high it really isn't that good on gas either even with the stock street gears...Maybe a 700r4 or th400 would be better? can i get some help

--Rome

[rome704]

ttt

[Orange77]

if your on the highway a lot then a 700r4 would be great considering it has the overdrive as well. They told me to do the same that it would swap right in. you'd only need to reroute some lines.

[asphaltburner]

Yo!
700R4. The TH350 and TH400 will give you essentially the same gearing,...the TH400 is heavier duty.
The 700R4 is an overdrive tranny and will lower your final gear ratio to reduce your rpms at highway speed. Search this, and the driveline forums for more info, but I believe it is a direct swap with the TH350.
Have fun! Todd.

[rome704]

Thanks well it looks like im looking for a 700r4 then

[JohnC]

Yeah for what it sounds like you are wanting I would go with the 700R4. That is the one I am switching my TH350 out for.

[rome704]

700r4 it is then thanks peeps

[rome704]

what car/truck donor would be best to get a 700 r4 off of

[79 silverado]

I'm going to assume you are a 2wd... In that case, you have tons of options...

* full size chevy/gmc trucks
* full size/mid size gm cars like the caprice, impala, etc (careful, some are 200-4r series)
* camaro/firebird v8 only (the v6 had a different bellhousing pattern)
* corvette

the list goes on and on.

The trick is, try to find one from the later 80s or beyond. The earlier 700r4 trannies were not *as* strong and are more prone to wearing out earlier due to some design flaws that were compensated for in the later models... It can be corrected in a rebuild so if you are just looking for a core its not as instrumental, but, if its a slap in and go situation look for the later years...

[larrystone]

If you a just using the truck as a car and not a work truck hauling a trailer, I would suggest that you just swap the entire rear axle with one from a salvage yard that has a 2.73 or 3.08 ratio.

[rigon4]

GM changed the 700r4 a little bit in late 87 and they are much better so look for some thing 1988 to 1992 for your swap

[rome704]

Originally Posted by 79 silverado

I'm going to assume you are a 2wd... In that case, you have tons of options...

* full size chevy/gmc trucks
* full size/mid size gm cars like the caprice, impala, etc (careful, some are 200-4r series)
* camaro/firebird v8 only (the v6 had a different bellhousing pattern)
* corvette

the list goes on and on.

The trick is, try to find one from the later 80s or beyond. The earlier 700r4 trannies were not *as* strong and are more prone to wearing out earlier due to some design flaws that were compensated for in the later models... It can be corrected in a rebuild so if you are just looking for a core its not as instrumental, but, if its a slap in and go situation look for the later years...

Yeah I'm 2wd Thanks for the List i wasn't sure so ill look for one out of something 80 or higher shouldn't b hard...

Originally Posted by larrystone

If you a just using the truck as a car and not a work truck hauling a trailer, I would suggest that you just swap the entire rear axle with one from a salvage yard that has a 2.73 or 3.08 ratio.

Yeah wont be pulling or hauling nothing well there is that mustang im getting soon but that's it...i wanted a higher posi ratio for the rear... What ratio is already in there...Isnt stock 2.73?...

Originally Posted by rigon4

GM changed the 700r4 a little bit in late 87 and they are much better so look for some thing 1988 to 1992 for your swap

will i have to changed the flywheel... and is there a stall you all could recommend?....Is the 700r4 longer? will i need a drive shaft? Just Curious

[rigon4]

Yeah wont be pulling or hauling nothing well there is that mustang im getting soon but that's it...i wanted a higher posi ratio for the rear... What ratio is already in there...Isnt stock 2.73?...



will i have to changed the flywheel... and is there a stall you all could recommend?....Is the 700r4 longer? will i need a drive shaft? Just Curious [/QUOTE]

For your ratio in the rear end look at your glove box sticker it could be anything
Your flexplate should be good.
A 9 inch tail shaft th350 is a 1/8 inch shorter than a 700r4

[rome704]

thanks bro new shaft as well

Yall have been alot of help

[Justins76]

700r4. You'll have overdrive for the highway and a better 1st gear for acceleration. The later ones have a aux valve body. Some minor adjustments were made by GM like when going from P to R or D it doesnt jerk.

[boatpuller]

i run a th350 and turn a little over 2 grand with 3.08 rear.and a little taller than stock tire.personally i like the th350.the other's do have o.d's which help.check you rear end ratio.it may be low.

[rome704]

i have no idea where to look i dont see anything thing about the rear ratio

anyone else has a 78 swb

[benoit454]

ther'es a sticker in the glove box with axle ratio on it or under hood on the fender well driver's side. Or you can pull the cover.

I personally hate 700r4's because if the tv cable aint right it'll be sloppy or burn up quickly. It seems to lack power IMO also. I never liked them.

I run th350's in everything and love em. Now the short tail th350 is shorter then a 700r4 so you'd need a driveshaft shortened or find a shorter one. Flexplates should be the same.

I'd run another rear end in it, one that's more highway geared like the one in our 84 it sucks it's a 273 and I hate it for take off. If you were closer I'd trade ya lol. I want a taller gear something for more take off and you want less gear for highway and less rpms.

You can also run taller tires, that brings the ratio into were you want it more.

[rome704]

Thanks for the Input

[silvereagle07]

You can also get the transmission from aftermarket trans shops like this site.
http://www.bowtieoverdrives.com/index.shtml
They also have good info on the site for the overdrives and tv adjustment.