Good point. With my 2000, at least I know I can wrench on it and keep it on the road for decades to come. I wonder why Harley did that in the first place?

 

Very simple! Since that design was introduced the performance of the engine has increased substantially and it is no longer robust enough. It is the same reason that Harley went to rubber-mounts on their big twins back in 1980 - reliability in the face of increased performance in an elderly design. You are much less likely to need to do maintenance on a current rubber-mount Sportster than an old solid-mount.

 

They can't sell new bikes if you can fix the old one! After all, it's all about the money!

 

Rubber mounts they went to for a smoother ride and they are much more reliable, less vibration, less parts breaking and shaking off.

But I'd bet a paycheck that the real reason for dumping the trap door transmission and going to a different case design on the 2004 and up Sportsters is because it is cheaper to manufacture.

 

That is very likely a contributing factor, but the trapdoor is a flawed design, from the point of view of increasing power. Also when installing the engine in a rubber-mounted frame the crankcases need to be very strong, as they also bear the weight of the swingarm and rear wheel. We have seen similar major changes to the way the transmission and crankcase of the big twins are joined together, to make them stronger.

 

I don't care, the way I still see it is no transmission door no new Sportster for me! Used to build the Harley US Twin race bikes and have had the transmission out to repair track side! Who is going to pay the dealer a $100 per hour to work on a 5-6 year old 883 that is worth ??? You might as well throw it away (what Harley is hoping) and buy a new bike! Do you remember the Harley ad's where they showed a Zippo lighter & a Bic lighter, under the Zippo they said our way of thinking & under the Bic they said their way of thinking? Well guess what?

 

The new transmissions are bullet proof. You hardly ever hear of any trans trouble. If you are as good as you say you shouldn't have any trouble splitting the cases. I am capable of doing any thing that needs doing to my 2014 Sportster including splitting the cases. Mine is right at 110 HP and I ride it hard. I've got 25000 + miles with no trans issues what so ever. None of the Sportsters riders I know have ever had to go into their trans and some of them have over a hundred thousand miles on them. Damned if I will set around and worry about something that may never happen.

 

Solid mount bikes, with their trap door transmission, are enormously more popular in drag racing than the rubber mounts. There are some awfully powerful bikes out there using Sportster trap door transmissions. The trans is very tough.They take a lot of abuse.

Back in the day, the XB Pro-Thunder bikes were all getting trap door conversions, for serviceability. Likewise the Buell XBRR factory road race bike (56 made) put 150hp to the rear wheel and used a trap door transmission. Rubber mounted motor, too.

I'm with VAFish. It was a cost reduction.

 

There's a fundamental difference between a race engine that is frequently rebuilt and a stock one expected to go to the moon and back!

 

You very rarely see out-and-out failures in the trans. What's much more common is worn dogs causing hop-out problems. You'll be accelerating and there's a momentary hesitation as the gears get pushed away from each other and then re-engage. I've had this happen on a couple different XL's over the years, and I know of several others who've experienced as well. It happens equally on both solid mount and rubber mount bikes, there's no difference in that aspect of the trans design. Here, let me show you what happens:





Once these get rounded like this, you start getting hop-out. Pretty easy to fix on a solid mount bike. Quite a bit more work on a rubber mount.

Don't get me wrong, I personally prefer the rubber mount bikes overall. But I view the loss of the trap door as a negative, and accept the fact that if I have a trans issue, I need to do a full tear down to fix it.

If you want rubber mount with a trap door trans,you can always get a pre-2003 Buell