I recently read on these message boards that the 5 speed manual tranny and the 5.0 only have a 3500 pound rated towing capacity. Before I knew about that, I had been towing farm equipment every fall and spring (including wagons that weighed WELL over the 3500 lb rating) Not to long ago I towed a 6000 pound trailor loaded with old hit and miss engines to a show. Then, I read on the boards that 3500 lbs is max. Why is that? Is it because the tranny's aren't strong enough to hold the weight? Or (this is what I'm thinking) the clutches aren't designed for it? I just turned 254,000 miles on my odometer, and replaced the clutch at 160,000 miles. If the clutches are the factor, why not buy a more "heavy duty" clutch?

 

Both. The M5OD is a very light duty tranny for a truck application, but most people who have trucks nowadays wouldn't notice or care.

The clutch is probably OK except that with a first gear ratio of 3.90:1 it's way too easy to abuse the clutch to get a heavy load moving. A heavier clutch would help, but the real fix is deeper first gear in a stronger box. That's why Ford puts the ZF 5 and 6 speeds in the 250s and 350s

 

I believe it is a little of both(The clutch and the transmission). I wouldnt worry about it too much. The M5OD is a pretty good tranny as long as you dont get too rough and start jerking it around a lot.
I exceeded that much weight with my old 92 F150 at least once a week for 2 of the 3 years that I owed it. I never had any transmission trouble and the factory clutch lasted 145000 miles. If you are worried about the tranny you could always put synthetic oil in it for a little insurance.

 

I'm gonna agree. Its both.

I pull a trailer 3x a week with 2,500-3,500lbs, and probably 4,000-6,000 once a month. I've done this for the past 5 years. I had a bad slider in the M5OD at 160k, but I think that is due largely to banging it around like others have said. 220k on the truck now. I've had the 351 in it now for 4 months and 5,000 mi. We will see how long that M5OD holds up behind that. So far so good. BTW I installed an 11" clutch when I did the swap, that made a world of difference. I dont even know why Ford bothered with the 10."

 

Keep in mind that the rear gears affect the rating too. Higher gears equal a lower rating, and vise~versa.

Take care,
~Chris

 

O.K., so there "rated" at 3500, but realistically, they are beyond that. Sounds pretty cheap to me. But, I've been breaking the rules fro sometime by quite a lot of weight with no problems.

 

I don't know about cheap. I've put 2 10" clutches in my truck over 100k period. This last time I put in an 11" and I am sure that will make a difference. My dad had an '86 with a 4.9L/M50D and put 4 10" clutches in it over 120k while working it hard. Nobody said they wouldn't tow more, just remember you'll wear them more. Depends on how much you use them. I will say that the M5OD deserves more credit than people give them, but I have to put the weakest link on a 10" clutch.

Remeber, like PKRWUD said, gear ratios make a big difference.