‘86 6.9, worth it or hold out?

[Hobbywelder]

Folks, I found a lady selling an ‘86 F250 6.9idi with a manual.

I know in relative comparison to the 7.3 it doesn’t have the power but it isn’t as susceptible to cavitation.

So: my two biggest questions are this:
1: what are my options for a trans upgrade to a 5 or 6 speed manual?
2: what wiring would I need to change to mount in a ‘93 recipient body?


Is it worth it, if the price is right? Or should I hold out for a turbo 7.3?

*I have no issues building the motor, but if wiring is a C/F, and a later 5 speed manual doesn’t mount then well....

 

[Thewespaul]

zf5 bolts on, you will need a new clutch and flywheel. It will also work in the newer cab but you will need to swap the serp accessories on and install zd9 glow plugs then your harness will plug in.

 

[Hobbywelder]

zf5 bolts on, you will need a new clutch and flywheel. It will also work in the newer cab but you will need to swap the serp accessories on and install zd9 glow plugs then your harness will plug in.

By new clutch and flywheel, as in brand new or a different one robbed from like a 7.3 or a 6.9 with a 5-speed?

so basically steal the more modern components like an alternator so the plugs are the same?

where would the glow plug harness connect given the donor body is a gasser?

 

[FrozenMerc]

Another Transmission option is the Ranger Gear Splitter. It is a 2 speed auxiliary trans that bolts in front of the old 4 speed. You end up with a 4x2 gear combination (8 forward, 2 reverse). I run one in my '85 F-350 with a NA 6.9 and a I really like it. I treat it like a 5 spd (Low Range: 1,2,3,4 - High Range), unless I am pulling a heavy load, then it can be handy to split ranges, especially the big jump between 2nd and 3rd.

Two things to be aware of:
1. They push the main trans back about 8 inches, so that will require a shorter driveshaft, and a new shifter hole in the floor. (Probably not a big concern with your cab swap)
2. They have straight cut gears - Strong, but a bit noisy. There is a noticeable gear whine, but to me that is better than the motor spinning 3500 rpm @ 65 mph.

https://www.advanceadapters.com/pro...tter-overdrive-27-with-a-5125-retainer-index/

The Ranger Splitter is cost competitive to a ZF-5spd swap, and much, much cheaper than a Gear Vendors unit. I went with the Ranger because I was having a tough time finding a good ZF.

 

[Hobbywelder]

Another Transmission option is the Ranger Gear Splitter. It is a 2 speed auxiliary trans that bolts in front of the old 4 speed. You end up with a 4x2 gear combination (8 forward, 2 reverse). I run one in my '85 F-350 with a NA 6.9 and a I really like it. I treat it like a 5 spd (Low Range: 1,2,3,4 - High Range), unless I am pulling a heavy load, then it can be handy to split ranges, especially the big jump between 2nd and 3rd.

Two things to be aware of:
1. They push the main trans back about 8 inches, so that will require a shorter driveshaft, and a new shifter hole in the floor. (Probably not a big concern with your cab swap)
2. They have straight cut gears - Strong, but a bit noisy. There is a noticeable gear whine, but to me that is better than the motor spinning 3500 rpm @ 65 mph.

https://www.advanceadapters.com/pro...tter-overdrive-27-with-a-5125-retainer-index/

The Ranger Splitter is cost competitive to a ZF-5spd swap, and much, much cheaper than a Gear Vendors unit. I went with the Ranger because I was having a tough time finding a good ZF.

thats not a bad idea. I would love to have a 4/8 speed. What kind of towing have you done with it?

what is your end RPM with it? I have a 4.10 rar, so I expect my cruising (75-80mph here) RPMS to be high.

 

[DaveBen]

By new clutch and flywheel, as in brand new or a different one robbed from like a 7.3 or a 6.9 with a 5-speed?

so basically steal the more modern components like an alternator so the plugs are the same?

where would the glow plug harness connect given the donor body is a gasser?

Your glow plug will not match a gasser. They do NOT have glow plugs.

 

[Hobbywelder]

Your glow plug will not match a gasser. They do NOT have glow plugs.

i am aware, hence why I asked where they would go. I would have to make an alternate connection or switch to manually use them most likely.

 

[IDIBRONCO]

i am aware, hence why I asked where they would go. I would have to make an alternate connection or switch to manually use them most likely.

Maybe Wes's glow plug harness would help. You'll have to draw the power for them from some place. I don't know, but another problem area may be the speedometer. If it runs through the computer on the gasser, then it probably won't work with an IDI.

 

[FrozenMerc]

thats not a bad idea. I would love to have a 4/8 speed. What kind of towing have you done with it?

what is your end RPM with it? I have a 4.10 rar, so I expect my cruising (75-80mph here) RPMS to be high.

I tow a 10,000 lb 24' Pace enclosed car trailer, I have drug that trailer all over the Dakota's, Minnesota, Iowa, Nebraska, and Missouri with no problem. My '85 has a 4.56:1 rear, so it is still turning around 2600 RPM's in overdrive at 70 mph. But it could not even hit 70 with the factory 4 spd without slinging the rods out.

 

[Hobbywelder]

I tow a 10,000 lb 24' Pace enclosed car trailer, I have drug that trailer all over the Dakota's, Minnesota, Iowa, Nebraska, and Missouri with no problem. My '85 has a 4.56:1 rear, so it is still turning around 2600 RPM's in overdrive at 70 mph. But it could not even hit 70 with the factory 4 spd without slinging the rods out.

Shoot thats not bad at all. Ill probably run about the same RPM’s or a touch less cruising on the interstates here.

4.56, SRW or DRW? Maybe the prior gens had a much higher ratio than im used to seeing.

 

[FrozenMerc]

Shoot thats not bad at all. Ill probably run about the same RPM’s or a touch less cruising on the interstates here.

4.56, SRW or DRW? Maybe the prior gens had a much higher ratio than im used to seeing.

Dually. I am the 2nd owner. The previous owner lived in the hills of Western Virginia and used it to pull car trailers up and down the Appalachians, and he never needed to go over 55. The Great Plains have a bit different profile....

 

[Hobbywelder]

Dually. I am the 2nd owner. The previous owner lived in the hills of Western Virginia and used it to pull car trailers up and down the Appalachians, and he never needed to go over 55. The Great Plains have a bit different profile....

That would explain it. I live in the rockies, and sometimes speed is important, and others the low end grunt and high gears make or break a trip.

 

[dgr]

...


2. They have straight cut gears - Strong, but a bit noisy. There is a noticeable gear whine, but to me that is better than the motor spinning 3500 rpm @ 65 mph.

https://www.advanceadapters.com/pro...tter-overdrive-27-with-a-5125-retainer-index/

....

Are you running the advanced adapter unit or an original? Advanced mentions helical gears. I'm curious about the gear noise between the two?

 

[FrozenMerc]

Advance Adaptor. I can't say I have ever pulled a cover to check the gear style. I just assumed straight cut due to the noise.