im thinking about going from a c6 to a zf 5sp in order to gain alittle mpg.
1.whats the difference between an auto trans starter and a manual trans starter?
2.what years was the zf used?
3.what years did they use an external slave cylinder with a 351w?
4.are there any reliabilaty issues with the internal slave cylinder or just a pain to replace it?
5.how many mpg can i get with the swap(for those who have done it before)?

 

I've done this swap a couple of times in various forms and here's my .02 worth.

1. I've been able to use the automatic starter with the manual tranny.

2. The ZF was from 1987 thru 1998 in various forms

3. They were all concentric (internal) slave cylinders. You have to use the tranny with a small block bellhousing (300, 302, 351)

4. Just a pain to replace since you have to remove tranny. My last one had 120,000 miles before needing changed.

5. This one depends on many factors. Differential ratio, tire size, driving habit, etc. Many will debate this but my opinion is if you keep your foot out of the gas, manual trannys get better mileage than automatics. I own nothing but manuals for this reason.

On a sidenote, you are not far from me. If you have trouble finding parts, email me. I have many extra Ford truck parts to help with your swap. I even have an extra ZF with a cracked transmision mount ear.

 

If it's just the ear, its easily fixed. Oxy/Acl torch and coated aluminum welding rods and that's over with in 5-10 minutes. Just don't overcook

 

Yea, I kinda figured it shouldn't be too much trouble to repair. I priced the rear piece new and they wanted $200 for it. The tranny works great otherwise. I only took it out of my truck so as not to damage it by only having one tranny mount bolt in it.

Thanks for the welding advice.

 

thanks for the offer but im going to a junkyard in NC (pullapart.com) to get a good bed and hood and to do the 5sp conversion.
right now, with my sig truck, im getting high 13 to low 14mpg now. i travel highway mostly @65mph, but have been known to have a heavy foot when merging.

1.about the flywheel, i have to get one from a 351w, right, because of the balancing?
2.also the driveshaft, just get one from a reg cab, 133"wb, zf truck and im done?
3.should i get the original clutch disc off the donor truck,install it so i could practice on it, or just get a new one?
4.whats the thickness of a new one so i can compare it to the used one?

 

Yes, you would need the flywheel from a 351W. The balance weight should be different between 351W and 289/302. Someone will correct me if I'm wrong but I believe 302 is 28oz and 351 is 56oz.

Yes on the driveshaft. Most of the ones I have seen are 2 piece with a carrier bearing. One piece may be hard to find. Your differential also makes a difference in length due to the pinion snout length difference between a Dana60 and Sterling 10.25. I have the driveshafts from a Sterling if you need them with carrier bearing and mount.

I would just opt for the new clutch. I only say that because a ZF is a heavy tranny to have to remove to change it later. As long as you don't ride it, clutches are pretty durable. I'm not sure as to the thickness of the clutch disc for you to compare. If you opt for the used one, the disc material should be thicker that the rivets holding it on. I would assume by about 1/16". If the material is getting close to the rivets, just get a new one. I just did my clutch and the disc set was only $130 with the throwout bearing. My kit even came with the slave after I had bought one seperately.

Side note, I took my ZF out of a 1988. It was behind a 300 six. I got about 19 MPG with 4.10 gears in back. Granted I drive like granpa, but is should give you an idea.

 

wow, you get 19mpg with a 4.10 rearend, what engine and which truck since its not the ones in your sig.
did you use a 2 piece driveshaft on your conversion?
any other helpful tips?
what did you do with your trans crossmember?
how long did the conversion take?
thanks for all your help

 

The truck I have is a 1988 F250 2wd. I took the 5 speed out of it and put a 4 speed in it now with a transfer case. I planned on a 4x4 conversion but don't know if that will happen now. I have always used a 2 piece driveshaft with a ZF conversion. Reason being is the ZF is a fixed yoke tranny. You have to have a slip joint somewhere for the driveshaft to shrink and grow with axle travel. Without custom making an output shaft for slip yolk, the 2 piece shaft is the only way to go.

I have the crossmember sitting in my garage. Most of the conversions I have done only took a weekend. Granted I had all of the parts necessary and some various extra parts just in case. My longest conversion was the above 88. I took the 5 speed out and put in a NP435 and NP208 x-fer case. This required going from hydraulic clutch to linkage due to the year bellhousing I had. It took about a week.

My best tip is to make sure you have everything you need. Don't start until you do. I started one assuming that all the parts I needed would be available in the local salvage yard and they weren't. I ended up fabbing almost the entire clutch linkage. That was in my dad's 75 F100 (auto to manual conversion). If you pull everything from one donor truck it is better. Mine always consist of parts from various years being inserted in to one truck. This makes it a little more time consuming but not difficult.

After seeing your truck and what you have done to it, you should not have any problems. Pretty straight forward. I'm happy to help if any questions come up that I can help with.

 

I'll correct you 351w and 81ish and older previous 302 have 28oz counterbalance, 82ish and newer 302 have 50oz imbalance. You are right about needing the 2 piece driveshaft.

I'm in the process of gathering parts right now to do a ZF swap in my 79. From my digging around, the 300, 302, and 92 and older 351w have an 11" clutch (or 300 may have had 10"), while the 93 and newer 351w used an 11.5" clutch (actually 11 9/16"). As far as I know this is the strongest factory clutch for the 351w. Took a while, but I picked up a brand new 11.5" clutch second hand (for about $75) and a year later an 11.5" flywheel (for about $50). The 11.5" parts are a lot harder to find than the older versions.

 

Thanks for the correction. Someone had told me before that the balance weight changed on the newer 302 but I never looked for any info otherwise.

Never heard of an 11.5" clutch before. Learned something new today. I only knew of 10" and 11". My truck had a 10" clutch and I changed it to 11" when I put the new clutch in. My flywheel had the tapped holes for both sizes. I'll have to start looking for that 11.5" clutch though for my 351W Mustang. The extra clutch would be nice for when I go out horsing around (no pun intended).

Great info.

 

lots of great info here.
can i use a driveshaft from a zf/sterling truck on my zf/dana?
what needs to be done to the crossmember?
do i need the one from the donor truck or use mine and modify it?

 

You would have to measure the distance from the axle centerline to the universal joint between the 2 different axles to see how much difference there is in pinion snout length. Depending on that number there might be enough slip in the slip joint to comensate. If not, you would either need the driveshafts from a truck with the same setup you are using or have drivshafts lengthened or shortend depending on need.

The crossmember is diffferent between the automatic and ZF. If I remember correctly, the crossmember from an automatic truck is straight across. The ZF crossmember has a "dogleg" in it towards the front of the truck so that it can use the common frame holes and still hit the tranny mount. The ZF mounts is further forward than an automatic.

I can send you a picture of a ZF crossmember so you can see what I mean. Email me and I can also send you a picture of the driveshaft setup you would most likely need.

 

I'll correct you here again too. According to my measurements for 2wd transmissions, a C6 is longer than a ZF, however, the mount on the ZF is further towards the rear of the truck than the C6, so the dogleg would point to the rear. For me, I think it means I need to make a custom tranny crossmember for my 79 to fit the ZF (unless by some chance an NP435 crossmember will work).

 

Your probably right on the length issue. The trucks I converted from automatic to manual were C4 to manual. You are correct about the mount. I went back through my notes and was bass ackwards. The offset in my crossmember went to the rear of the truck.

Funny you mention the NP435. When I removed my ZF and put in an NP435, I used the NP435 crossmember from an early 80's truck but Had to flip it upside down in order to use a transmission mount. I used the crossmember from the truck I removed the NP435 from but in my 88 is forced the transmission to sit higher in the frame. Never did figure out why. All of my measurements from the older truck matched up with the newer one.

 

thanks, a picture is worth a thousand words.
i have a questions about the carrier bearing, where does it attach to?
i think that was about the last of my questions to you, you have been very helpful in my quest for more gas mileage and having a 5sp in an 80's truck