ZF 5 Speed- good or bad?

[46stude]

Whats the feedback on the ZF 5 spd trannies that came in the late '80s- early '90s F250/350 trucks?

I want OD behind the EFI'd 300 in my '69 & was going to use the ZF, but a post in my thread over in the "Project" forum says it might not be a good swap. Any bad problems w/ these transmissions that I'm not aware of?

I know they're not as low in 1st as the 435 or T19s, 4th is 1:1 like in the 4 spds, & that they're prolly not quite as tuff as the cast iron 4 spds. But if ones taken care of properly & only abused occasionally, am I still gonna have trouble?

My truck is an F350, & will be worked like a 1 ton- no cushy life in store for this truck. Whatcha got for me?

[AustinTom]

I have one behind a 351 in an 89 that I have never had any major problems with. I beat the truck pretty bad as it is my work truck, and the only thing I've ever noticed is that the syncros aren't the strongest. I'd say go for it.

[FLATBEDFORD]

Got one in my '96 F250. Only problem I had was with hydraulic clutch. The slave cylinder developed a leak. It was replaced under warranty. Only about 70,000 miles on it now and it hasn't worked that hard either.

[xxxtina63]

If given a choice, go with the ZF, not the Mazda 5 spd. They are much more durable and I think they are designed for use with a V-8. An I6 should be no problem. Also, any trans that has an inboard slave cylinder is prone to problems eventually. Once they start leaking they will saturate the clutch with fluid requiring replacement.

[46stude]

The Mazda 5 speed is not a good trans for a 1 ton dually, & not really even good for a truck period. I'd never consider it, don't worry.

[oldschoolrods]

I know people that have run the ZF 5 and had good results. Only one had the synchro problem as someone else stated

[studdmstr]

Say you are switching from a Ford 3 speed to a ZF trans will a new trans crossmemeber need to be fabricated or the original used and relocated back?

[averagef250]

The ZF's are pretty tough. I put a 98 ZF 5 speed mated to a 205 behind a 1000+ ft/lb 24 valve cammed 5.9 cummins in a customers '87 F-350 4x4 and it's holding up pretty good so far.

The mazda M5R2 would be plenty to handle the EFI six. I wouldn't worry about the ZF at all. The M5R2 will get better mileage than the ZF. There's just less spinning around in there.

[46stude]

I don't think the Mazda would last long w/ me. Here's my 300 powered '81:

[46stude]

And yes, the truck pulled it. I was not insane enuff to actually drive down the road, but I did move it around on the property. Funny thing is, theres a 360FE sitting on the bed of the truck, too. I figured the 14X80 mobile home wasn't enuff weight.....

[averagef250]

That could exceed the recommended GVW for an M5R2! I definitely agree! I have used several M5R2's and EFI sixes in older trucks with good results though.

[46stude]

Built Ford Tough

For me, its not just a slogan- its a way of life!
The '81s 300 is bone-stock & backed by a worn-out T18. I didn't block the springs, either- the truck carried the weight on its own. I've got several pics of the '81 loaded down, but the mobile home is the most impressive by far!

And if someones thinking "yea, it moved that, but I'll bet it messed that truck up afterwards", think again. I did that 2 or so yrs ago & still drive the truck & work the snot out of it today- never any problems after moving the trailer house!

Thanx for all the feedback everybody. Looks like I'll go ahead with the 300/ZF combo. I just can't find much more than a couple bad reports on the ZF, & FoMoCo put them in a ton of trucks over the years.

[FLATBEDFORD]

You gotta love those 300 sixes! I had an '83 F250 with a 300 six and 4spd. That truck could move anything as long as I wasn't in a hurry. I think my old 300 had more grunt than my '96 with 351.

[averagef250]

I agree that built Ford tough is definitely not an exageration. My old '70 hiboy has done several feats over the years that would have made excellent Ford commercials had someone had a video camera. The truck has sat at 34,500 GVW with a 30 foot tandem dual trailer loaded with 9 WWII vintage swiss cam screw machines and several tons of spare parts. The rear axle alone was over 10K. I took the load over the cascades and 350 miles total. 45 MPH was all she'd do up the passes and I warped the rotors coming down, but she did it. I say not bad for weighing 5 times the max GVW and 9K over CDL requirements.

[46stude]

I have had over 10K in concrete blocks & pads on the bed of my '81, plus the tools & jacks, etc for house moving- prolly near 12K on the bed, I would guess.

Ever heard the expression "it can pull a house"? The '81 has done it a few times. Not mobile homes, but real houses loaded on beams & dollies.Didn't use it to hold the weight, but it did pull the weight. I haul scrap iron, too, & have had some pretty heavy loads run over the scales.

All in all, the '81 has been the best darn vehicle I've ever owned. Poor things getting pretty rough now- 9 years of hard work by me, not to mention that it was previously owned for years by a roofing company & hauled roof tear-off debris! Thats why I'm building this '69 F350 to replace the '81. I honestly don't plan on beating on the '69 quite as bad, though!