If I understand correctly, a A518 trans has a non lock-up TC and an overdrive
unit in the trans. Correct?

Is an aftermarket triple disk converter a type of lock-up converter upgrade?
Could someone please enlighten me on how it works?

 

Yes it is for a lockup transmission. A normal A518 is non-lockup.

 

so if I get one I'll have OD plus a lock-up TC?
What would I need to do to make it funtional?
another switch in the cab?
or do you just not run it in lockup in our application?

 

You just get a non-lockup torque convertor for the A518. There are plenty of companies that make them.

The transmission that has lockup is called a 47RH, aka A618. You can't just add a lockup torque convertor the the 518 and make it a lockup transmission, there's more to it than that, but I don't know what else you need. There are people who know more than me and they will probably post later.

 

you'll need a different input , different valve body, a different pump a different engine adapter

Easier to just get a 94-95 47rh trans and swap it in or just buy a tight converter for your non lockup A518 which is what i'd do.

Basicly it's a pain to convert your 518 to lockup, there's alot to it.

 

I would contact Spec-Rite Torque Converters....they built a converter that held c. 700rwhp and a 7.2 at 98mph in the 1/8th in Cole Dow's truck. I would buy and try their converter before anything else!

 

From what I have heard the trans company P.A.T.C. has made a electrical hook.up that makes it a lock up,only in 4th gear @ 55 mph maybe in 3rd gear, yes you need to buy alock up converter,part from P.A.T.C. is $65.or $85.00. I don't work for company just read there web page check out there Mega Viper III rebuild it yourself,have a shop do it

 

This.

 

P.A.T.C. makes there own triple disc as well,according to them they said not a lot of was involved,don' know for sure

 

A lockup converter won't fit on a box stock non-lockup A518. The input shafts are different, 1 spline off. Non-lockup has a solid input while the lockup has a hollow input. The input shaft support is different between the two, its the part that sticks out from the front pump on the trans and has the splines that engage the stator in the torque converter. The valve body is similar, but has an additional solenoid to control the lockup circuit. The torque converter is different of course, the lockup converter is an inch longer to make room to put the clutch disc and apply piston. And the engine adapter that is meant to be used is an inch thicker to accommodate the additional converter thickness.

To convert a 518 to lockup you would need to:
change the input shaft to a lockup one. Free to cheap if you know who to talk to.
change either the front pump or the shaft support to a lockup type. I bought a whole front pump for about $50 a few years ago from a trans shop.
add the required parts or acquire a 47RH valve body. I would get a whole valve body from a vender all setup.
secure the proper 3 pin connector for controlling lockup and OD. Junk yard or PATC.
A lockup converter of course. This is the expensive part if you buy a good one.
And the thicker engine adapter from 94 to 02. Hunt around, they are pretty easy to find.

Then to install it you need to follow the instructions in the following threads.

https://www.dieseltruckresource.com/...d.php?t=114702

https://www.dieseltruckresource.com/...d.php?t=236738

If you know a good trans shop that is willing to sell you parts its not that bad. The real advantage with the 47Rx's is you get a better/stronger low/reverse band. Double wrap vs. single wrap with a better anchor point. There's other hard part updates that have happened over the years, the big on started in 96 with the 47RE. They began using 5 pinion steel planet carriers vs aluminum.


I'm pretty sure any lockup converter they make is the standard dimensions for a lockup one, about an inch longer than a non-lockup unit.

 

Sorry bud but that's for the gas version of 518 they are lock up.