6.9 Jeep Swap

So it looks like the clutch needs to be replaced. I'm thinking a transmission swap is in order. Any thoughts on a ZF-5 vs an NV4500?

Personally I don't like the zf5.
Nv4500 is stronger. Can actually get beefed up internals too.

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Isn't that the 5 speed that was available behind the 6.5? I don't like that one because it drops the engine 1500 rpm between shifts. That's clear out of the boost range unless you're at the govenor!

I have both, the close ratio ZF5 is my preference. I like the way the NV4500 shifts but the RPM drop from 3-4 is awful. I've found myself skipping right from 3rd to 5th occasionally with the NV4500 just because I have to wind up so high in 3rd. I also have the early GM NV4500 with the lower first gear so your results may vary.

The ZF s5-42 (which is 99% of what you'll find available) isn't a bad transmission, per se. It's rated for 420ft-lbs of input torque, but it'll take a /lot/ more than that.
Justin @ R&D had one behind his 400+RWHP IDI(something like 1,000 ft-lbs of torque), and the transmission didn't blow up. Clutch had a real hard time holding that power, though.
I'm currently running 460 at the wheels, which is a bit more than that at the crank. No issues on my transmission.

The main downside to the ZF transmission are that the synchros are 'weak'. I'm not sure if they are weak in general, or simply the rest of the transmission outlived it's design life by a long time, but most any ZF transmission you find will have some worn out synchros.

Common symptoms are:
1. Hard to get into second gear when moving. I've got a couple which will do it if you rev-match, but if you try to force it, they'll grind instead of going into gear.
2. 3rd gear being 'notchy'(hearing a few teeth bouncing off before it goes in). Also related to worn synchros.
3. Reverse synchro being shot - this results in it being hard to put into reverse(also possible to have it pop out of reverse, but I've not seen that).
What I see is where you put the transmission into reverse, hear it not quite go in, let the clutch out just a hair while holding the gearshift and hear a 'clunk' as it finally engages.
That, or having to put it back in neutral, let the clutch out for a second, press back in and then quickly put it into reverse(so the input shaft was still spinning) at which point it goes in just fine.

Also, I've got a couple of transmissions with bearing noises from something or other; rest of the transmission seems just fine though.

Despite all that, they tend to work just fine, handle high torque, and I'm quite happy with mine, even with the synchro-issues.
Someday I'll try to rebuild one and fix it, but it's not something that's in the 'must be fixed' category.

Thanks for the input! Looking at the cost of adapting I'm probably going to go with a ZF when I find one available. I've considered the rebuilt ones but they are spendy. I may put a new clutch in and then wait till I find a good deal on a ZF. Almost had one but it sold before I could get there.

Yes, they were in the gm trucks. Also used in the dodges. Which may have better ratios.

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79jasper said:

Yes, they were in the gm trucks. Also used in the dodges. Which may have better ratios.

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Well you made me curious so I looked it up.

The pre 95 GM NV4500 is the deepest geared of all of these transmissions.

The 95+ GM and all the Dodge variants were geared slightly higher. 95+ GM and Dodge NV4500 gear ratios are identical between the two manufacturers, with a couple minor exceptions (reverse gear in the later years).

95+ GM and Dodge NV4500 is VERY similar to the gearing of the Wide ratio ZF5.

Apparently the two variants of the close ratio ZF5 were geared slightly different from each other.

My experience is with the lowest geared NV4500 with the widest spread, and the highest geared ZF5 with the closest ratios.

If you don't count the gearing at all, I prefer the "feel" and ease of rebuilding of the NV4500. If you count the gearing, I prefer the close ratios of the ZF5 behind my diesel. I love the NV4500 behind my SBC, except for the spacing between 3rd and 4th.

Also need to consider the special fluid the NV4500 requires is about $35 and only available from the dealer or online order, use the wrong fluid and kiss your synchros goodbye. ZF5 takes regular old ATF. $12/gal at Wally world.

But technically, the same is true about the fluid with the zf5.
Many have "tried" other fluids and messed them up.

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Until I find the right deal this is all strictly academic. I'm putting in a new clutch/flywheel with a cleaned up T-19. Just going to get it going well until I can swap the body and hopefully find a good deal on a ZF or NV by then.

So, did new glow plugs, new return line set (found at least 2 that were leaking and another that was on the way. May have a bad injector line, will see when it is running. Adding a coolant filter, wix fuel/water separator, and a lift pump. Also looking into hydroboost brakes so I can ditch the vacuum pump (I don't have anything on vacuum now except the little bit for the heater and that will go away, the jeep uses cables for the HVAC controls).

Here is the one I made out of tool steel.

laserjock said:

Unless you have the correct tool don't knock the freeze plugs out. They are not standard freeze plugs. If they arent leaking, I'd leave them in.

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Do you rent it out? Looks nice. I was planning to make one that was good for a couple of uses.

FoolhardyIDI said:

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Here is the one I made out of tool steel.

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I ended up putting a standard 1.5" cup style in the hole above the starter. Permatex and a full depth install mean it's probably not coming out any time soon.

I've gotten most of it back together and hopefully I'll have a complete f250 this weekend. As for the swap I may do that in June. Just take a week off to get it all swapped over and new frame mounts built.

Almost finished putting everything together. Spent an hour at Home Despot trying to find the right fittings for the fuel/water, fuel pump, coolant filter. Finally gave up and put in an order to mcmaster.

For anyone looking, the part numbers to adapt the Napa/wix fuel/water separator, transicold lift pump, and napa coolant filter head are:

F/W - 53525K57
Pump - 53525K16 + 53525K17 + 50785K27 (Replacement elbow and barbed fitting and extenstion for stock filter)
Coolant - 53525K22 (the kit includes non-barbed fittings but figured it's worth it to keep everything consistent)

Hoping to have it up in time for the weekend.

On a side question, the upper and lower radiator hose fittings that bolt to the block were pretty corroded. Are new ones available or is it a salvage item?