What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

New transmission recommendations?

8

86k5Blazer11

Registered Member
Joined
Mar 18, 2009
Posts
16
Reaction score
0
Location
pa
If I was to get a new transmission for my 86 sense mine burnt out, what would be best? My blazer has a 350 from an 89 blazer. I need something pretty bulletproof, automatic, cheap (I could find it in a junk yard?). Is the 700r4 a good choice?
 
if you change trans you'll probably have to change more than just a trans. Most are mated to a particular combo of trans output shaft/ t/c input. If you change from your existing type trans get everything else with it.....t/c, driveshafts, shifter etc.
 
if you want bulletproof and cheap, the th400 would be best, but then again whats the cost of you switching everything out you had, and your time to do it. Id just roll with what you had for cheap..
 
I've heard the 700R4 is the same as the 400 but with overdrive. So if you wanted you could drive around in D and have the same thing as the 400. The benifit is you have overdrive which improves your gas mileage.

Correct me if I'm wrong anyone, I'm only repeating what I have been told.
 
nsxxtreme said:
I've heard the 700R4 is the same as the 400 but with overdrive. So if you wanted you could drive around in D and have the same thing as the 400. The benifit is you have overdrive which improves your gas mileage.

Correct me if I'm wrong anyone, I'm only repeating what I have been told.
Click to expand...

The 400 is a lot stronger. But if you have a 700r4 currently, getting a good rebuild is the way to go.
 
700r4 is very similar to the TH350 not the TH400.
Th400 is a lot stronger, longer, and has diferent output shaft splines.
The 700r4 is a good trans but the eariler models had some bugs and weak points that were worked out buy 1988. If you get a 700r4 get one with the later model case 1988 and up. Do not get a 2wd 700r4 their cases are weaker than the 4x4 case and can crack. 4x4 700r4 has a big K cast into the case to ID it.
4l60 is the same as 700r4 and has all the upgrades.

If you need a cheap replacement you can use a TH 350 out of a 4x4 truck. It will fit and bolt right in.
You will loose overdrive and may take a small hit in your gas milage. You will need to do is run a vaccum line from the intake manifold to the vac modulator on the trans.
 
Keep the TH350, better tranny than the 700r4.

My advise to would be a rebuild, when going with a used tranny you never know what you are getting, I've been down this road with used tranny's before and none of them lasted too long and in the end it cost me more than had I just got a rebuild. Also the TH350 & 400's are CHEAP to rebuild.
 
Thunder said:
700r4 is very similar to the TH350 not the TH400.
Th400 is a lot stronger, longer, and has diferent output shaft splines.
The 700r4 is a good trans but the eariler models had some bugs and weak points that were worked out buy 1988. If you get a 700r4 get one with the later model case 1988 and up. Do not get a 2wd 700r4 their cases are weaker than the 4x4 case and can crack. 4x4 700r4 has a big K cast into the case to ID it.
4l60 is the same as 700r4 and has all the upgrades.

If you need a cheap replacement you can use a TH 350 out of a 4x4 truck. It will fit and bolt right in.
You will loose overdrive and may take a small hit in your gas milage. You will need to do is run a vaccum line from the intake manifold to the vac modulator on the trans.
Click to expand...

1 big flaw in your info. you will need a specific length 350 2wd tranny and the spacer kit to keep drive shafts in the same locations. its sold in a whole kit shaft/spacer/and other goodys.
 
Thunder said:
If you need a cheap replacement you can use a TH 350 out of a 4x4 truck. It will fit and bolt right in.
You will loose overdrive and may take a small hit in your gas milage. You will need to do is run a vaccum line from the intake manifold to the vac modulator on the trans.
Click to expand...


That's exaclty what the previous owner did to my '88 Sub. Even though I'm probably losing 1-2 MPG's not having OD, I still feel that overall, the TH350 is a stronger tranny. I had a 700R4 in my old '90 Blazer and I never used OD when I look back. I don't know why as it was a rebuilt tranny, but I just never used it.
 
I see nothing wrong with a WELL rebuilt 700r4. My father drag races his 82 K10 with a 700r4 behind 450hp 500 torq and has never had problem. Though a 400 is stronger overall I see nothing wrong with rebuilding a 700 strong and using it. The 700r4 really just has a bad rap from the first initial crappy stock ones (86-87)
 
I have not used a 700R4 in a 4x4 but I have abused a built one in my Corvette with slicks. I didn't have any problems, but it does shift a little hard. I rebuilt the trans myself and had a 2600 stall. Nothing radical, but it held up. Good luck.
 
nsxxtreme said:
I've heard the 700R4 is the same as the 400 but with overdrive. So if you wanted you could drive around in D and have the same thing as the 400. The benifit is you have overdrive which improves your gas mileage.

Correct me if I'm wrong anyone, I'm only repeating what I have been told.
Click to expand...


the 3L80 is the same as a TH400....and the 4L80 is the 400w/ overdrive
4L80e electronically controlled.

3/4= forward speeds
L= longitudinally mounted
80= strength of unit (to what measurement I'm not sure)
 
Probably a stupid question, but is the 350 the engine or transmission you are referring to? You never quite mentioned that in the original post. You might just want to rebuild whatever it is you have, or hit the junkyard to get a replacement for what you have. All 3 transmissions (350 400 700r4) are different lengths, requiring possible drive shaft changes, TC changes, kickdown changes... Stick with the same type as what you have. The 350 or 700 can be located relatively easily either in a junkyard or on Craigslist but you should still have it checked out.
 
My car had a 700r4 in it that burnt out. Can I just get a th350 and bolt it in?
 
You must log in or register to reply here.

Latest Posts

Top Bottom