TH350 - Lock-up or Non-lockup? Any Preference

[houston54]

I am currently running a non-lockup TH350 in my truck but picked up a lock-up TH350 last night off the local craigslist.  The tranny now in the 54 was another craigslist purchase during the construction phase and was supposedly "rebuilt" just prior to the sale.  It is now starting to seep a bit probably from dry seals but I dislike a vehicle that marks it territory and am planning to drop it out.  

Would I be better off having the lockup TH350 gone through and use it?  

The truck is driven to/from work in mainly highway traffic situations.

[zzford]

The answer really depends on your type of driving. If you are just pulling short local trips, it probably wouldn't be worth the effort or expense. If you do a lot of long distances at highway speeds, I'd say go for it. My coupe has a 700r4 that I drove for about a year before I finally got around to hooking up the lock up converter. On the open road, it makes a significant difference in mileage.

[1FATGMC]

If you drive it much and are going to change why not go to an overdrive and pick up a real difference in gas mileage?

A 200R4 would most likely go in there with the same drive-shaft and just a change to the  rear cross-member and some electrical hookup.

c ya,

Sum

[EMSjunkie]

I don't mean to.....but I'm gonna steal this thread for my own selfish purposes :oops:  

I scored a T-400 tranny for the C-cab a couple weeks ago....how do you tell if its a "lock up" tranny :?:
the one I scored has a deep pan, and an electrical connection on the left side, about 3/4 of the way back toward the tail shaft. it is a single connector, looks like it screws into the side of the case.
I'll try to get a pix of it this weekend.

OK.....now back to your regularly scheduled program..........

Vance

[enjenjo]

If it has only one wire, it is not a lockup. Even two may not be a lockup. The single wire is for the electric kick down. Second wire can be switch pitch convertor, spark retard, or lockup, depending on the model and year.

[Crosley.In.AZ]

first ;

there never was a t-400 built with a lock up converter.


second ;

the weak part of the t-350 lock up trans is the converter.  The spring loaded hub inside the converter was prone to failure.

[kiwipaul]

What is lock up ? Is that what we call Cruse and use to call Auto pilot?

[enjenjo]

What is lock up ? Is that what we call Cruse and use to call Auto pilot?

A clutch in the convertor, that locks up to eliminate convertor slippage

[mcdonald]

No Paul the lock up is a place in town thay put Ned kelly so watch out .       Lindsay

[kiwipaul]

Same as McDonald Brothers

[houston54]

To get this back on track ....  The truck currently has a TH350 non-lockup trans in it that is slipping a little and marking its territory.  The rear axle is a 2.41 posi out of a 78 T/A, the engine is a 280 HP/300 Ft Lbs SBC mild compression.  The truck is to see use as a daily driver to and from work.

Will the lock up tranny be a positive addition to this rig?

[enjenjo]

To get this back on track ....  The truck currently has a TH350 non-lockup trans in it that is slipping a little and marking its territory.  The rear axle is a 2.41 posi out of a 78 T/A, the engine is a 280 HP/300 Ft Lbs SBC mild compression.  The truck is to see use as a daily driver to and from work.

Will the lock up tranny be a positive addition to this rig?

For fuel economy, yes, in most cases. Should increase it from 1 to 5 percent. FWIW, I have a lockup 350 in one of my cars, without the lockup connected, it has been in there for a number of years with no problems.

[1FATGMC]

..................... The rear axle is a 2.41 posi ..............................

Forget my suggestion on an overdrive trans....wouldn't work well at all with that rear gear,

Sum

[phat rat]

..................... The rear axle is a 2.41 posi ..............................

Forget my suggestion on an overdrive trans....wouldn't work well at all with that rear gear,

Sum

That's for sure. My 3.42 comes out to 2.39 with the 700R