2550 broken hood mounts

[CCinCT]

If it had been a heat-related failure, you'd see some deformation. But because his picture doesn't show any melted or deformed plastic, I believe its a stress failure.

In my opinion, the main shortcoming of the current plastic hood is reduced access to the engine bay when compared to the older metal 3-piece design. I don't care for the 3-piece design much, except for how the top folds forward and away to provide unhindered access to the engine bay. It seems to me that the current hood could be front mounted in such a way to mimic that older feature. The problem would be in stopping it's forward travel at some point in a way that didn't load the hinge too much.

The current "automotive" style hood access has no actual value, other than to look kinda cool to bystanders that haven't had the pleasure of working under one.

 

[JSharp]

Having worked with a lot of molded plastic parts I agree this is a stress failure. But why?

I notice Cub is using self tapping screws to hold the hood onto the hinge assembly. It's not the best way and most that use molded parts won't do it on any assembly that's stressed. The screws put too much stress on the boss they screw into, or alternately can't provide sufficient clamping force unless the hole size and assembly torque is exactly right. And if wrong you can get thread stripping, or cracks in the boss like we're seeing here. Either way the assembly will fail.

Even when you get everything right the overall assembly isn't as strong as one that uses a threaded insert and machine screw. Too much stress, too many ways to put it together wrong with a thread cutter.

In the case of the these failures though it's hard to tell specifically what happened.

Hinge was moved too far at some point, or moved with some of the fasteners loose or missing? Improper assembly of the hinge? Poor molding of the hood and hinge attachment area? Hood material losing some of its mechanical properties because of elevated temperatures? It doesn't matter though does it? All of these things point back to Cub since it's highly unlikely 2 posters caused an identical problem on 2 different tractors. It also makes it less likely it's just a fluke or random occurrence.

I think we all know the "advantage" this hood assembly provides and why it was done. The $$ advantage to Cub. I still think it's possible to make one that works just fine. I wonder, do we hear JD and Kubota owners complaining about theirs? I wonder too how much of that money Cub saved will in turn fall into the pit of warranty claims. Not to mention the long term cost of customer dissatisfaction.

What Cub does about all the hood issues will tell a lot. If they fix these things promptly and modify the product to eliminate these problems in the future I say good on them. If not, and they adopt the automakers technique of starting to deny warranty claims to cut warranty costs, then I say good luck to them. There's bunch of people in Detroit and elsewhere that can tell them how that'll work out in the end...

 

[JSharp]

What do I think? Plastic hoods suck and should not be used on lawn and garden tractors that get hot and bounce and bang around a lot. I have a metal hood on my 682, 26 years old and not a single crack or melt in it. Scratches are superficial, and the occasional metal rattle does not bother me. When someone spends upwards of $3000 for a garden tractor, I think they expect a little bit better than cracked and melted plastic.

-Fordlords-

But if it lasts 26 years you won't buy a new one. You'll just rebuild the engine or install a new one. Then you'll keep on using it...

 

[CCinCT]

I think we all know the "advantage" this hood assembly provides and why it was done. The $$ advantage to Cub.

And to JD, Kubota, Simplicity... all of whom use plastic hoods in at least one line of tractor. And none of them are particularly impressive either, in my opinion.

 

[JSharp]

And to JD, Kubota, Simplicity... all of whom use plastic hoods in at least one line of tractor. And none of them are particularly impressive either, in my opinion.

I know almost everyone uses plastic now. I've never really studied how they do it though. As I said before, I wonder if the other brands have seen these kinds of issues too.

Problem is I think, by the time you're done using a plastic part and doing it right, it may not be all that much cheaper than the old way. And knowing how to use plastic parts correctly is a diffrerent world. It's really easy to do it wrong...

 

[CCinCT]

The only other brands' plastic hood that I've seen up close and person is on a JD LX175? Not sure that's the model number, but it's close to that. Anyway, it was a 1999 or 2000 model year lawn tractor with a plastic hood that hinged in the lower front, right above the bumper. The hood was broken at the hinge points from the owner running into something. I didn't see any inserts, but then I wasn't really looking for them either. I will say that the fit of the hood was tighter than our Cubs. But then the whole engine area was shrouded by that hood per design, so that would make sense. Point being, Cub should take a few pointers from JD in that regard: they made a front hinged plastic hood that controlled airflow better, and kept more dirt and debris out of the engine compartment.