7.3L with a C6, durability question

[scfdiesel]

Hey everyone, I am completely new to this forum or any forum really for that matter and also new to the diesel world. I've always loved everything obout diesels; power, torque, sound, turbo's, fuel source possibilites etc.. and I have a 1979 f150 I bought a 1990 7.3L idi with 52000mi on it to be converted. I'm having a local diesel mechanic do the swap and he said he found a C6 that would fit the bell housing and 4x4 transfer case. I know the motor originally was mated to a E4OD which I think is a more heavy duty tranny. My question is; is this tranny going to be strong enough, were there many different 'forms' of the C6. I would like to put an aftermarket turbo on this motor as well...probably an ATS, any input on that issue would also be greatly appreciated.

Thank you very much for any input in advance.

 

[towcat]

welcome to the site.
the E4DOA is the younger brother to the C6 but flunked college.
you're better off going with the C6 and a add-on overdrive.
there's a few members here who have done the conversion into a pre-'80 chassis and it's not a hard one to do. you will be challenged slightly in modifying the firewall for the turbo though.

 

[david85]

Stock for stock the C6 is stronger. Stock for stock the E4OD is much more fuel friendly.

If you have the time and money, a build up of the E4OD will give you the best of both worlds. Knowing the build history of the transmission would also help. OEM rebuilds made after 1995 are comparable to C6 transmissions for durability. The right upgrades will make the E4OD bullet proof, but the C6 is already strong in stock form.

Depends on what you are after. If you are mostly off road with the truck then the E4OD is a waste, but if you like to cruise on the highway at 70 MPH or more, then the C6 will suck the fuel down as fast as an H2 hummer sucks gas.

 

[scfdiesel]

thanks a lot for the replies. Does the C6 with an add-on overdrive come close to the E4OD fuel economy? What would a E4OD build up require you to upgrade in the transmission, what would descent quality parts cost?

 

[david85]

thanks a lot for the replies. Does the C6 with an add-on overdrive come close to the E4OD fuel economy? What would a E4OD build up require you to upgrade in the transmission, what would descent quality parts cost?

I don't keep any secrets about my build

remembering what I did does get harder but I'll try and list them.

Gear train:

In 1997 ford offered a "superduty" build up E4OD that had all steel carrier planetary gears. Main forward was a 6 pinion, overdrive became 4 pinion, and reverse was 6 pinion. This is a factory Ford upgrade, but they are so popular that aftermarket suppliers carry them as well for decent prices. For your info, the C6 has all 3 pinion aluminum carrier planetaries and all E4ODs originally had them as well.

I bought the steel gear upgrades for the forward and overdrive planetaries. The overdrive planetary comes with a new stronger input shaft in most cases. What is interesting is that the power enters the transmission through the overdrive planetary so its always under load even if you are in 1st gear. Cost was about $100 off of Ebay for the OD gears and shaft.

I didn't bother with the rear planetary since that isn't subject to much load and at the time all you could get was a complete universal kit that was over $250, however now you can get only the planetary for around $100.

The torque converter:

I paid about $735CAD locally and had the following upgrades:

billet front cover,
internal structual brace to prevent balooning,
tripple clutch (no amount of power changes the lockup time)
furnace brazed internals (factory ones are crimped together)
Something about a bigger torrington bearing, don't quite remember.

Have seen comparable TCs on Ebay since then for less, but I wanted to buy something closer to home in case something ever goes wrong. Been perfect so far.

Center support:

One of the most critical internal upgrades came with a change of the center support bearing. 89-94 transmissions had a bushing where later ones had a ball bearing. You can get an upgrade kit that includes the center support, steel forward/overdrive planetaries and new imput shaft for under $400, or parts can be found seperately. If the transmission was rebuild after 1994, it should already have the roller bearing center support so its best to tear yours down before ordering upgrades.

Pump:

The front pump was changed in 1995 to have 15% more capacity. Got a used one off Ebay for $70 but had to change some of the valves in it. Since I spend a lot of time below 2000 RPM and above 70 MPH at the same time, I was concerned about cooling and pump pressure.

Rebuild kits:

Prices vary from $100 to $300 usually depending on how complete it is.

Shift kits:

After all is done, get a shift kit that makes changes based on orifice holes in the separator as opposed to just adding stiffer springs. The spring based shift kits are easier to install and remove, but they put more strain on the valve body valves and rise line pressure causing more heat. Opening up orifices allows fluid to more quickly fill clutch pistons allowing a faster shift without added strain on other transmission components.

Controller:

I am running an aftermarket controller that uses fewer input signals and will never throw a fault code or go into hard shifting. It costs close to $600, but I can't imagine using anything OEM after using this. Mine is set up more like a 5 speed than a 4 speed because the TC only locks up at about 50 MPH and overdrive engages roughly at 65-70 MPH. 3rd or 4th are perfectly viable at 70 MPH thanks to the 3.08 gears. 3rd works great for towing at 70 MPH.

OK, now about the fuel economy question. Simply put, an E4OD backed up with the right gears will give better peak MPGs than a C6 GV combo no matter what gears. The C6 cannot lock up the torque converter, so there will always be slip no matter how tall your gearing is. 2000 RPM is about the lowest you can get with an open torque converter in these trucks before slip negates any gearing advantage you might have (and making heat). The E4OD also has a wider overdrive ratio than a GV overdrive. Its also a myth that you can't tow with an E4OD in overdrive.


wiew, long post.
Hope it helps

 

[punkmechanic]

I will just back up what others have said. For simplicity and ease of stock components go with the c6, If you plan on this being a daily driver then your gonna want to build up the e40d or get a gear vendors for behind the c6.

Or you could go manual and swap in a zf5 and have it all, you just have to pick your gear.

As for the turbo, look into hypermax. Great kit, 1800 to your door with warranty and instructions. And hypermax will answer your questions and know what they are talking about. Ats is a good turbo, the company just sucks to deal with when you need to rebuild/upgrade/replace. Used kits are out there and you can save a lot, but you have to know what to get and what parts are going to need updated or replaced based on the kit you get.

just my thoughts on the topic.

punk

 

[Agnem]

Wow David! That's a great post. You just earned a spot in the IDI Tech Articles.


I did a C6 build up, and it's true. They are one tough transmission. Bigfoot uses one, and I was told it's just about stock. However, you will really miss having an overdrive gear, and your fuel economy will never be what you could get with a lock up clutch and an overdrive. I'd strongly consider putting a ZF in your 79' F-150 conversion. Tell your mechanic that we have experienced people here who have already done this truck build if he has any questions.

 

[scfdiesel]

Thank you everybody for all of your input especially David for that in depth review of tranny's. I have some decisions to make on that. This forum is awesome and I do really appreciate everyone's thoughts. I have a couple more thoughts or questions to add if anyone was still interested commenting on this conversion. My truck is currently a manual tranmission 4sp with granny gear. The granny gear wore me out on manual tranny's for the moment as my other vehicle is a manual too. The vehicle the donor motor is from had a 2wd E40D (1990 E350 ambulance conversion) I don't guess there is a way to mate this to a 4x4 transfer case...if I used that one I'd have the extra money to rebuild it with stronger components. If I kept the truck manual, would I be able to have it 're-geared' to do away with the granny gear? This truck's primary purpose will be a semi-daily driver with some towing of about 4500lbs. Does anyone have any further pro's/con's to offer about the ZF transmission?

 

[david85]

Wow David! That's a great post. You just earned a spot in the IDI Tech Articles.

Thanks, now I won't have to write it all again if some one asks .

I think the E4OD is actually a good foundation to build on with the right things in the right places, but you have to know what changes were made over the years to really do a smart build. Anyone considering the option of building up their E4OD should get the rebuild manual as well as the update manual. The update book is just as thick as the rebuild book and is packed with info on updates that were made, when they were made, and the reasoning behind them. I used the ATSG manuals and are pretty good ($20 each).

Not unlike the IDIs, combining different years of E4OD parts will get you the best results. 1989-1994 had the worst reliability from factory, but also had some of the strongest hard parts in some places.

 

[sootman73]

Thank you everybody for all of your input especially David for that in depth review of tranny's. I have some decisions to make on that. This forum is awesome and I do really appreciate everyone's thoughts. I have a couple more thoughts or questions to add if anyone was still interested commenting on this conversion. My truck is currently a manual tranmission 4sp with granny gear. The granny gear wore me out on manual tranny's for the moment as my other vehicle is a manual too. The vehicle the donor motor is from had a 2wd E40D (1990 E350 ambulance conversion) I don't guess there is a way to mate this to a 4x4 transfer case...if I used that one I'd have the extra money to rebuild it with stronger components. If I kept the truck manual, would I be able to have it 're-geared' to do away with the granny gear? This truck's primary purpose will be a semi-daily driver with some towing of about 4500lbs. Does anyone have any further pro's/con's to offer about the ZF transmission?

to mate it to a transfer case you would have to unbolt the tailhousing. you would also have to change out the rear output shaft to a 4wd version. that requires tearing the tranny all the way apart to get to it. but since you would be building it up anyway it really wouldn't be that much of an issue.

another source of info might be from these guys but im not sure how much they will tell you. they have one of the best reputations in the country for E4OD buildups. they have power ratings higher than you will ever achieve with your idi. like 600+ hp made for sled pulling or drag racing.
http://www.brianstruckshop.com/

 

[scfdiesel]

Thanks once again for all the input. I finally talked to my mechanic and he is in agreeance with the E40D build up so now I think I'll go ahead and get those manuals to further educate myself so I'm able to understand what the mechanic will be talking about parts wise. The mechanic mentioned he knows another local shop who specializes in tranny's and he could probably go to them for some used parts to do the build. Should I insist on using only new parts or is that not worth the extra money if good conditioned parts are used. From David85's info the new parts before a shift kit or controller would run around $1000 which would be at the higher end of what I would want to spend before labor. Just wondering if anyone had any thoughts on that? Also, I have pretty well decided on the hypermax turbo from peoples input and price. Do any of the 3 turbos available perform significantly better/differently than the other?
Thanks everyone. I'm going to start taking some pics of the conversion in the works to post if anyone would be interested.

 

[david85]

For used parts it depends on what you want to use. Wear items like cutch frictions should not be reused, but hard parts like center support, and gears can be reused if they are in good condition. In fact, there are some used parts in my transmission. A torque converter is a wear item though, since it houses the lock up clutch internally, so unless you are 99.9% sure about the history of the part, I wouldn't use it.

But hard parts like shafts, gears and newer sprags could probably be reused as long as you clean and inspect them very closely. Those are not really wear items and should outlast the transmision unless a major internal failure happens.