How do crashboxes work? I guess I understand that they replace the transmission but what are they? Are they drive specific, how do they hook up? The reason I am interested is I am having my Twin Disc 502 trannys rebuilt and it is pretty expensive and they will still be overpowered. How do the old ones that require you to shut off the engine to shift differ from the ones available now. This is a KAAMA drive boat. Thanks.

standoff boxes are spacers that go between the drive and the transom and change the x dimension of the boat used in high performance applications

most crash boxes require you to shut the engine off to shift which requires a large set of bals at the dock. Ther are some air shifted versions around today that are shiftable while running. There are a few guys around here that run em and love em. Do a search for air shifted crach boxes and you will come up with the info you need.

unless you are running BIG power, you probably don't need or want crash boxes... i would just upgrade to better trannys...

For some reason the Twin Disc MG 502s seem to be the only trannys used with these drives, perhaps it is the only one that has the correct dimensions/ output angle? The dealer that has the trannys says they will not reliablly handle anything over 450 Hp(Twin Disc also confirms this). They have a new Twin Disc tranny that won't be a direct bolt in(may not fit at all really) that they want to sell me for 4k. So, Im looking for alternatives ideas. I asked the engine builder to keep the power around 500 hp because of these trannys. I would go higher if able. I hear stories of people racing these drives/trannys in the 1980s at 600-700hp 5800-6000 rpm. Don't know who to listen to. I don't have enough money to screw up, it needs to be right the first time. It would be nice to hear from someone that has direct experience with these drives from back when they were still in production. Archer was the one that told me about the power levels above, but how reliable were they? I don't want to be rebuilding them on a regular basis like I guess the race teams did.

So do I:
1- rebuild my MG 502s which the dealer and Twin Disc both say will not last at over 450hp and take my chances.
2- spend 2x the money for a Twin Disc 5050 that probably won't fit(they are still looking into fitment, butare already reccomending them) but I won't know for sure till I buy them.
3-Somehow find out why the MG 502 is the only tranny ever used with these drives and why another tranny won't fit.
4- Crashboxes, which I know nothing about, even if they can be used with these drives, and financially would probably be older ones that require you to shut the engine down.

i would look into a huber transmission... then you can upgrade the motors all you want...

In most applications crash boxes will take the place of a transmission with some driveshaft modification due to length. So If a different transmission wont fit then you will find problems with crashboxes also. Most boats running crash boxes are over 1300HP to give you something to compare too. There are more boats than you can count running over 1000HP using trannys reliably.

I was looking at crashboxes based on my assumption that the Twin Disc tranny is the only one that would fit. I have to think that if another tranny fit someone would be using one. Yes, the crashboxes would not fit without dropdown boxes for the drives, which MIGHT be available.

huber mods them borg warners nice..