A 518 trans qUESTION?

[pmartinez]

Ok I have decided to go with A 518 trans in my 87 suburban. What I need help with is, what do I have to do to make this trans shift right? Is there a wiring harness or kit available or a modification I can do? Any help would be great.

 

[Hutchew]

A guy I know used a 518 w/ lockup convertor in his conversion and he used a dimmer switch to control lockup/OD functions. PIA if you ask me (I'de rather row, anyway). Should have a three prong connector on the side, if I recall correctly, center post is positive, outside posts are switched negative, one for OD, the other for TC Lockup. He just hits his switch and the TC locks up and transmission shifts into OD all at the same time. I'm not saying it's the right way to do it, but it worked for him.

 

[michigandon]

I am contemplating controlling the OD manually on my conversion as well. It's really the only way that I have much faith in the setup being reliable. I still have a really bad taste in my mouth from the '92 W250 I used to have. Damn thing used to go through TPSs like I go through changes of underwear (Never heard of the TDR nor did I know that you could clean and adjust them at the time).



I'd rather row too. In fact, the next CTD that I owned was a five-speed. Unfortunately there's really no practical way to install such a setup on a Class A forward-control motorhome chassis.



Don

 

[backroad]

I agree with your using the 518 transmission in your swap. It's really a lot better unit than most people give it credit for. For upgrades, I'd just find a competent transmission shop and go talk with them. Valve body work is definately in order for your firmer shifts as it tends to build less heat. In my swap, I went to the trouble (and lots of it) of converting the converter to a lock up type, simply to help reduce the heat buildup when towing. Especially In an application of a heavy vehicle. On a motorhome conversion especially. Isn't a suburban kind of like a motorhome?



It's imperative that you run some kind of awesome transmission cooler. Keeping an automatic cool is truly the life blood of an abused transmission. Derale (bought through Summit Racing) makes an incredible unit (quite like the original Dodge HD unit) that is rated for 25,000 GVW and includes a mounted fan. I believe that Summit is right now having a sale which also included a thermostatic switch for about $135. Normally the swithch is another $30 or so. THe cooler can be mounted anywhere. This is especially good when doing a swap that has limited space by the grill. I'm mounting mine just in front of the rear duals, under the bed. Be sure to keep the original heat exchanger in line. It's also a cooler in warmer conditions.



Have lots of fun with your conversion. Patience is a virtue, and u will need a bunch (ROFL)...

 

[pmartinez]

Backroad the 205 transfer-case that you used, was it a dodge or ford case? I am gonna use the original NP 241 that I am going to change the input shaft. But I am open to any suggestions if the 205 is easier adaptable. I know that is much stronger. let me know, thanks!

 

[michigandon]

I think backroads advice is pretty sound. I am sticking with a non-lockup unit (for now). While the transmission was already out of the vehicle I had a Transgo shift kit installed and replaced the stock converter with a low-stall HD unit from Mojave Green.



I have the OEM HD trans cooler that came out of the donor truck on hand as well. Hopefully the thermostat and fan motor on it are all still OK. I'm kinda contemplating eliminating it and the wimpy little grille mounted cooler in favor of a unit like this:



http://store.summitracing.com/partdetail.asp?part=SUM-G4969



But the jury is still out on that one. It depends on whether or not I have sufficient clearance up front, as well as the integrity of the components that I already have on hand.



Don

 

[backroad]

The 205 transfercase is kind of a story, but... ..... I was puting in in a Ford with the front differential on the driverside and the Dodge was on the passengers side. I used a 205 Case from a divorced Ford unit and put the Dodge/Cummins guts in it because they're a little better and newer. Had to us the Ford shift rails and forks and had to also build the shift linkage. I did take a litle lining up and drilling and taping to mount the Dodge transmission to transfercase adapter bell to the Ford Case and part of it did hang down below the Ford Case a bit so I simply remade the bottom inspection cover with a support coming up to the bell adapter. The part of the bell adapter that hung down was simply a reinforcing part of the casting and I could have let it alone but... .

And there is no fluid inside the adapter. All in all it was not too bad and I feel comfortable with the all gear TC...



If I had one of the Dodge HD Trany coolers, I would have used it. They are very good. When Dodge had them, they sold for about $450. OUCH!... . I didn't have one and the Derale unit was a good option and affordable. I'm so cheap sometimes... I'm not running any of the original coolers that were be hind the grill. I had to cut away too much just to get in the hugh Powerstroke Intercooler. I may later try to find a place to mount an oil cooler, but it's not really necessary as the Cummins already has one built in. Just overkilll.



Swap on... ... ... .

 

[backroad]

Michigandon, just a note. I would probably not use that particular cooler from summit. I would definitelly opt for the 16 pass, 25,000GVW cooler with the fan. Be sure and order the cooler with the larger 8AN fittings as the 518 use huge oil lines.

 

[pmartinez]

one more question. What is the final drive ratio of the A 518? So that I can pick my tire size and gear ratio's for my axles.

 

[backroad]

Originally posted by PMartinez

one more question. What is the final drive ratio of the A 518? So that I can pick my tire size and gear ratio's for my axles.

From what I understand, the 518 has the highest overdrive of all the overdrive automatics. It's a . 69 OD. Pretty cool huh?



I've convertered my four wheel drive dually to run the 35/12. 50X16 tires. It did take a spacer between the duals. I'm running 4. 10 gears and all this calculated out to 1700 RPM at 70 MPH. If you were to run a tire that is about 33 inches tall it comes out to only 1800 RPM's at 70, still with the 4. 10 gears. I'd really be afraid to run the 3. 54 ratio, especially for towing.

 

[pmartinez]

Backroad, I was wondering how strong the A518 is? I currently run a turbo 400 with a gear vendor o/d in my 89 Chevy 3500 dooley with a 93 CTD, Is it as strong? I also was brain storming about the toggle switch and dimmer switch idea for activating the o/d on the A518. On my gear vendor it automatically switches to o/d at 40 mph. So I have put a call in to GearVendor company so that I can purchase a brain and speed sensor to try and activate this o/d. I would like for it to be fool proof because my father age 70 will be the main driver of this suburban. I will let you guys know if I can get it to work.

 

[backroad]

I would definitely be interested in a control systems for the overdrive on the 518. I'm still in the process of buttoning up the last details on my conversion and the "electronics" part of the transmission is on the list. But, I guess for now, toggle switches will work, they just have to be remembered.



In my opinion the 518 is one of the best OD automatics built. Just needs to be "personalized", and I'm a Ford fan. From my experience, I would be far more worried about the Gear Vendor Unit that the 518. Still, they do an excellent job.

 

[michigandon]

Hey, thanks for the heads up on the coolers backroad. I guess I'll just try to use what I've already got on hand. Hopefully there's nothing wrong with the farn/thermostat/wiring on it. It does appear to be very heavy duty.

 

[Boilerman]

518 trans

P. Martinez

I have a question concerning the GM turbo 400 your using. Can you supply the part numbers for the readers to convert there Cummins engine to the Chev. turbo trans. Some of us would like to stay with the turbo and GV overdrive.

Thanks

 

[pmartinez]

Boilerman give me a day to get the info from my folder at work and I will post tomorrow. I did get all the peices from a cummins dealer.

 

[Boilerman]

518

P. Martinez

I'll owe you a six pack.

 

[pmartinez]

Boilerman here you go,





flywheel housing 3910516 superseded to 3908528 or 3906801

flex plate 3918957

crankshaft adapter 3907701

torque converter adapter 3908124

clamping ring 3904361

cap crews M12x1. 25x32

 

[Boilerman]

518

P. Martines,

I thankyou for taking the time to answer my questions. I and the others that are working on this conversion. thank you.

I mean what I said the beer is on me.