518 conversion

[Smokin 90]

Hi everyone,

I hope you guys can help me out, the 727 auto in my truck died today and I was wondering what I would need to install a 518 in its place. Iam sure I will have to replace or cut down my current driveshafts. but what else do I need to do ( OD button on dash, steering column, kickdown cable, etc). The truck is a regular cab longbox 4x4 if that helps. I want to make sure I've got everything to do it right.



Thanks for your help.

Kurt.

 

[BushWakr - RIP]

Wow, 60 "views" and no takers..... hmmmmm they must all be on holiday or something...



Well you will need the wiring harness for the temp sensors on the transmission. They control the min-max temps that trigger OD on/off based on operating temps.

I think you'll need to mod your crossmember.

The switch on the dash you already noted, but you can get the shifter lever from a 2nd Gen truck that has the OD button on the shifter tip... that is a better option as far as I'm concerned...

You may want to improve on your auto transmission cooler system if all you have is the basic unit.

I can't think of too much else that would be different... you mentioned the drive shaft modification/balancing...

While you're at it, get a flexplate from a newer truck and put that in... they're a bit more sturdy. . just a bit.

Make sure that the center steady bearing has a 1/2" spacer between the mount and the bearing bracket. This basically "stands off" the bearing downward to help with occasional shudder that has been experienced by some.

Have the transmission pulled apart and gone thru... at the very least have your pressures tweaked, your band adjustment checked, and a shift kit installed to help out with the firmness/power transfer.



Oh and if you have a 3:54 limited slip, then take it out immediately and send it to me and I'll send you an open diff that will work WAYYYYYYYY BETTER !!!



BOB.



EDIT: oopps I missed the 'regular cab' part. no steady bearing in the center then... sorry. .

 

[hdm48]

Bob, leave the poor guy alone.

 

[BushWakr - RIP]

RATS !! my cover is blown already..... ahhh well...



bOb

 

[Smokin 90]

Thanks Bushwakr,



Does anyone know where I can find the wiring harness I will need to do this, and do I also need a TPS for the OD? also do I need to change my starter and will the 518 bolt up to my engine with no mods. The reason I ask is that I saw somewhere that I would need to change those as well. I will be installing a new transmission with a shift kit and heavy duty servos. The transmission shop will include a high performance torque converter with a stall speed of my choosing, what stall speed should I have.

The truck has just some minor pump tweaks now but I plan for more mods in the future such as exhaust, 16cm housing bigger injectors and pump timing.

Thanks,

Kurt.

 

[cerberusiam]

Ok Bob since you shamed us into responding I will further compound the issues.



I don't believe the models with the 727 had a PCM (somebody that has one verify this). The OD button from the later models sends a ground signal to the PCM to shift to overdrive but it also uses the TPS to control shift points. Without the PCM (and correct wiring) the buttons and TPS are of no use unless a manual system is used. The same for the temp sensor as its output is to the PCM for monitoring. If the truck has a PCM my question would be does it have the neccessary firmware and wiring to control the OD.



All the electronics aside, the A518 is an out-of-production item that had some major design flaws. All the research I have done to this point indicates that the costs involved in upgrading to the newer transmissions is not as significant as it could be. It is a given the 518 can be made into reliable unit. Its also a given the 618/47RH/47RE/48RE models have the benefit of 10 years of experience and updates to improve all aspects of its operation. I have some reservations with using the $$$ to build a good unit and not have the benefit of the updated models.



IMHO, getting the most bang for the buck would indicate moving to the a 47RH at the very least. If you are considering a performance rebuild then also consider moving to the new 48RE. Depending on how much BOMBing you intend to do, a stock 48RE unit may be all you will ever need.



It all boils down to how much are you willing to spend. Is it feasible to drop $4000 on a $6000 vehicle? Thats an answer that is specific to each situation, truck, and owner.



BTW: Bob, I hear you can buy an LSD unit from DC.

 

[Smokin 90]

Thanks guys for the help but I think I am just going to have my 727 built up and put back in. I would really like the OD but at this time my budget won't allow that option right now. but when it does it's nice to know that it won't be too hard to do. The company that is rebuilding my trans is giving me the option of stall speeds and I am not sure what I should run. I am thinking of somewhere around 1200 to 1500 but like I said I am not sure, any ideas?? I quess I will just have to live with the fact that my buddy with a powerjoke will continue to pass me after 65mph

Thanks,

Kurt.