crashboxes/KAAMA/TwinDisc?
 

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.

Re: crash/standoff boxes ?
 

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

Re: crash/standoff boxes ?
 

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.

Re: crashboxes/KAAMA/TwinDisc?
 

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

Re: crash/standoff boxes ?
 

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.

Re: crash/standoff boxes ?
 

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.

Re: crash/standoff boxes ?
 

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

Re: crash/standoff boxes ?
 

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.

Re: crash/standoff boxes ?
 

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.

Re: crash/standoff boxes ?
 

huber mods them borg warners nice..

Re: crash/standoff boxes ?
 

The reason they were used was because:
1) they are capable of full power forward or reverse. So one engine doesn't need to be counter-rotated.
2) they have a built in 1.5:1 gear reduction.
3) they have a drop center, dow angle output which lines up with the drive.
A crash box has none of this, so give up on that idea.
Check with Huber, Bam, etc. they may have a solution for you.
Gary

Re: crash/standoff boxes ?
 

BAM was recommending a ZF-80. Problem is fitment. The drive coupler is already probably as short as can be and the engines are pretty close to the front right now. I don't know how close because they aren't in the boat now.

Re: crash/standoff boxes ?
 

Ive got the number for bam, anyone have contact info huber. Didn't find it on a search.

Re: crash/standoff boxes ?
 

It looks like the dropdown from input to output shaft is 5.65 with the output being at a 10 degree angle. It looks like the distance from the front of the tranny(not including bellhousing) to the out put shaft is 9.1 inches.

Re: crash/standoff boxes ?
 

I would talk with Rik at Arneson

Re: crash/standoff boxes ?
 

Huber Marine's Phone # 225-927-6895
Great Choice.



SCS shiftable crash box
About $ 9g's per engine, it think that answers your question
SCS Shiftable Crash box link

Good luck
Cougarman

Re: crash/standoff boxes ?
 

Don't know where Huber is located, but you can't get through due to the hurricane.

Re: crash/standoff boxes ?
 

Arneson's a good choice. I'm sure they've put together lots of trannys for inline ASDs. Rik is on the board.
Again a crashbox wont work due to the issues above.
You may also want to check with BAM, Huber, etc to see if they can upgrade yours, or the 5000 series BW, Hurth, or can set up a drop center, gear reduction 72C tranny for that much HP.

Re: crash/standoff boxes ?
 

Baton Rouge, LA


Spoke with them a few days ago they are open and up and running so keep trying.

Cougarman

Re: crash/standoff boxes ?
 

Seems like the biggest problem with using a different tranny is getting the necessary drop. There is about a 5.65 inch drop from input shaft to output shaft, then the output shaft itself is at a 10 degree down angle. The Twin disc dealer is still looking into the possibility of using another one of their trannys. I did get a hold of huber, but at a different number. Will talk with them again later. The Arneson conversion is just too expensive for me.

Re: crash/standoff boxes ?
 

Check with Arneson on a tranny. Their inline drives require a dropped, down angle output as well. They might reccomend a tranny that will hold up to more than 400hp and 4500rpm.
BTW, the 5000 series BW, Hurth, and ZF gearboxes all have a dropped, down angle ouput.
Gary

Re: crash/standoff boxes ?
 

I am going to inquire with Huber about the trannys mentioned. I believe Twin Disc owns Arneson, so they should be aware of the available trannys.

Re: crash/standoff boxes ?
 

If he's talking about no more than 500hp engines, then why not just re-glass the transome so a set of Bravo's would fit up? Wouldn't that be about a wash cost wise to new tanny's? Parts, resale, etc. would benefit I think. The take off parts could be sold to help offset the cost of the B1's.

Re: crash/standoff boxes ?
 

i think he said he would put more HP in it if he could....

Re: crash/standoff boxes ?
 

I was limiting myself to 500 Hp because that was a number I thought the trannys could reliably handle. If they could handle more I would build for more.Now I am being told by Twin Disc and the dealer they will not hold up to that, so I asked the question here to try to explore my options to handle more power. As far as re glassing the transom for bravos that is not something I would consider as this entire transom is new, never even been wet and I'm not really concerned with resale value. What I would really like is for someone with experience with these drives from when they were still in production to give me some idea of what these trannys can handle power and rpm wise and be reliable in a pleasure application. I've heard 600hp@5800 rpm, but I'd like some conformation before I start spending money and blowing stuff up, especially since the stuff coming apart would be obsolete drives and transmissions that are getting harder to fix.

Re: crash/standoff boxes ?
 

I recall seeing a twin disc spec sheet. And the MG 502s were only rated at 4500rpm max, and I think 400hp. Most of their trannys are better suited for low rpm diesels.
Although I think the Kamma package usually came with Cyclone engines, 400-420hp and 5000rpm. That may be the maximum reliably.
Gary

Re: crash/standoff boxes ?
 

You are correct in what they rate them at from the factory. The highest output KAAMA package that I am aware of was 425 HP from Innovation Marine. I was told that when racing them they were putting 600-700 Hp before changing to crashboxes with dropdowns for the drives. How reliable were they at those levels ? Were they rebuilding them every race, were they failing during races. It was also pointed out to me that those power ratings(from factory) were probably for near constant duty for thousands of hours which is why they could handle soo much more during short term use like a 500-1000 hour life. Make sense ?

Re: crash/standoff boxes ?
 

Just got off the phone with Huber. He says not much can be done with my current trannys and even if I managed to upgrade them, the drives would be very close behind as the next weak link. He seems to think all would be happy at 500 HP. He also explained that the difference between these drives and the Arnesons that prevents you from using their trannys is that the Arnesons have built in drop boxes, so you don't need a trans with a drop.

Re: crash/standoff boxes ?
 

Only the ASD6s and 8s are available with drop boxes. You still need a tranny, but it can be an inline without the requirement for gear reduction or full power reverse.
There are a couple members on the board with inline ASD drives (no drop boxes). You may want to post a question under:"What tranny to use with 600hp and inline arneson"
Gary

Re: crash/standoff boxes ?
 

inline arnesons.....

Re: crash/standoff boxes ?
 

Thanks for all the help. I think based on the cost, work and general PITA involved in a 20 year old boat that is not going to increase much, if any in value no matter what I do to it I will just rebuild the 502's. I will decide on the HP I want to throw at them, maybe play it safe at 500(I have decided that 500 is safe despite what TD says), maybe take my chances at 600, definitely no higher than that. Sad thing is that for close the price of rebuilding the 502's, I could get some much higher capacity trannys, if only they would fit.