Does anyone have a picture of what this would look like? Is it similar to how Reverse is engaged in a standard honda transmission? I understand what a straight cut gear is compared to a helical gear, but the "dog engagement" I don't understand. Why would it not grind? Why is it not favorable for a "streetable" car?

 

The "dogs" are the teeth on the syncros. With straight cut gears you remove every other tooth, but still use the syncro. You can still grind, but with a forceful engagement, the straight-cut gears are very reliable. What makes it difficult for a street car is that you have to slam gears the same cruizing slow as you would WOT at the track...that can get a little annoying all of the time (plus they have a constant gear whine...like in reverse). Trying to granny shift a dogbox will just wear it out.

 

Ah...completely didn't think about the whine.

Is there an explainable reason why a straight cut gear with synchros with half the teeh on it grind much less than the common counterpart?

 

hey I have been looking into these also. I don't have any pictures though. I think there are some pics on SAENZ website.

This setup is supposed to be awesome for drag racing, but you have to "positive" shift always like you are dragracing. Downshifting is not recommended, however i do not know why.

I also asked my tranny guy about these and he said that he has put something very similar into VW trannies and the only down side is that he has seen a fair # of the gears wear out within 50 hard passes. I called SAENZ and they were wishy washy about that issue. They said they have seen them last more than one drag season but they said it depends on how many misshifts you have.

anyway I can get the gear sets for around $3000.
just my $.02

 

http://www.magnusmotorsports.c...n.asp

Here's a link for Magnus' gears for dsm's. There's a small write-up and pic. According to Magnus, they're fine for downshifting.

 

Good site!

Here's the picture and the info cut and pasted for the lazy people:



The Magnus Dogmission

DSM’s are notoriously hard on transmissions. They have been known to take quite a bit of abuse, far more than they have been designed for. As for being indestructible; they are far from it. Anyone who drives a modified DSM will tell you, you have to be gentle with the transmission and let the power do the work.

Enter the Magnus Race Program.

We had come to a point where there was plenty of power but we could never get it to the ground properly. 1st gear was too short, synchro’s would always have to be replaced and 4th gear would constantly shatter. The cost of transmissions was taking its toll.Some time in 2001 we went to the drawing



board and set out to see if we could fit a dog engagement gearset into a Stock DSM case and do it at an affordable price. In the same gearset we would also need the capability to withstand over 800ftlbs of torque

Three 3 years later.

Extensive research and testing has brought us, to introduce for sale to the public, the Magnus Dogmission.

The Magnus gearset is completely new featuring all new gear ratios and designed by racers for racers. The Dogmission is made out of a superior material over the factory box and is designed to take all of the punishment we could put it through. Every piece is proprietary, by Mitsubishi guys, for Mitsubishi guys.

***

Q. What transmission case does the Magnus gearset fit into?
A. The gearset will fit all AWD DSM transmission cases from 1989 to 1999. If you own a FWD we can modify an AWD case to accept this gearset. For FWD owners we can also provide you with a choice of three different final drive ratios depending on the tire size you wish to run.
The gearset slides into a 1st gen or 2nd gen AWD case with little modification. All you have to do is remove the 5th gear synchro brake and shave down the outside cover. The center differential is replaced by a spool, which reduces cost and provides a 50/50 torque transfer for AWD. Excellent for drag racing. If you want to run a 4 spider differential, or an aftermarket differential, Magnus can custom adapt your existing center differential to fit.




Q. Can I just use one or two gears out of the Magnus gearset in my DSM transmission?
A. No you can't use just 3rd and 4th for instance. The material is one of the weak points of the Mitsubishi transmission so teaming up good gears with weak gears is just not worth it. You would find the Mitsubishi gears would break and ruin up your good gears.




Q. How much power can The Magnus Dogmission handle?
A. The Gears were designed to withstand 1000 ft lbs of torque. We have however tested it up to 700ftlbs in our racecar.




Q. What are the gear ratios?
A. Gear ratio's are as follows:

The first number is the actual gear ratio.
The second number is max mph @ 9000RPM on a 24.5" diameter tire.
The third number is max mph @ 9000RPM on a 26" tire. We calculated it using these numbers because these are the most popular tire sizes for slicks. Radials for the stock DSM are somewhere in between around 25”.


1st 2.429 57.2 mph 60.7 mph
2nd 1.579 87.9 mph 93.3 mph
3rd 1.174 118.2 mph 125.5 mph
4th 0.885 156.9 mph 166.5 mph
5th 0.690 201.3 mph 213.6 mph

Final Drive (stock) 3.8667

We are not factoring tire growth of 2" diameter usually by 120mph (on slicks) this means that theoretically you can take it past 170mph in 4th gear. This means one less shift in the quarter mile, and you don’t have to run your engine to dangerously high RPM levels.

The Ratio's were chosen as a best all around ratio for both different tire sizes and in between tire sizes (radials). These ratios also allowed us to use the strongest possible gear and tooth profiles. The best possible all around choice.




Q. Is a longer first gear bad for my launch?
A. No, actually a longer first gear is very desirable. It allows you to attain a higher speed and keep that momentum when shifting. Most factory transmissions are designed for the old school 0-60mph or 0-100kmh sprint test. This just happens to be an industry standard that is used as a marketing point when selling new cars. You will notice that most cars will reach 60 mph by the end of 2nd gear. By throwing out this practice and choosing our own ratios we can hold it in 1st gear longer which will provide a better launch and help you attain better quarter mile times.




Q. How fast can I shift it?
A. You can shift it as fast as you want and as hard as you want, but you MUST shift with authority. you cannot wimp out as with a synchro set. Driving a car with a crashbox (as dog engagement transmissions are sometimes called) really makes you feel alive! It is the purest sports car driving experience. You may use the clutch or ignition interrupt to shift. You may also or lift off the gas or gently touch the clutch, it is your choice. Because we back cut the dogs, there must be a momentary release of power to shift. This is so the transmission will stay in gear when you remove your hand from the shifter. This makes it suitable for roadrace, and road use.




Q. Is it good for the street and does it wear differently?
A. You can be soft on the shifts by using the clutch, but you still must shift fairly quickly. We also use a very thick oil that softness up the shifts dramatically. The oil is made by MOTUL for dogboxes.

Rest assured if you shift it fast hard and with conviction IT WILL GO INTO GEAR NO MATTER WHAT.

On the other hand, shifting like a sissy and missing the gear will cause the most wear, you must be firm and direct. If you shift slow as with a synchromesh box the dogs will not engage fully and they will start to chatter against each other. This is the only time you will start to see excessive wear. Basically premature wear is caused by misuse. If this happens to you quite often and it is time to service the box, the rings and gears can be sent to us for re-cutting, which will save you money, in place of having to replace the whole piece as with a current synchromesh transmission. Mind you it is not as delicate as a synchromesh. It will take a lot of missed gears to wear out the dogs. Whereas on a standard DSM box, miss the gear once and you may as well throw the gear, synchro and sleeve away.

One of our pre-production test boxes had over 200 passes on it. While we would normally turn a stock box to mush after 20 passes on last years 750hp 2.4 motor.



Q. How much faster will the Dogbox make my car?
A. Every time we have switched to a dogbox we have been able to knock .5 seconds off our quarter mile time from the shifting, they last longer before tear downs, and are eventually cheaper in the long run. Expand that over how many times you shift in a roadrace car or rally car and you can see why a dog box can be so beneficial to times.




Q. Do I have to match revs to downshift?
A. No just shift the lever in to the next lowest gear to down shift. Driving a Dogbox really wakes you up. The driving experience can be harkened to driving a real sports car, not something that anyone's mother could drive. Downshifting is great, just slow down and slam the lever, it’s in. Up shifting in corners gives a whole new meaning to 4 wheel drift. Just imagine slamming the next gear going from second to third in a constant power slide, no interruption in power, no weird/pitch/roll and dive conditions from having to clutch in, shift, release.




Q. Aren’t helical gears stronger than straight cut gears?
A. Yes and no. Manufacturing parts or making parts that will work together is all about compromises. Although it is true that helical gears contact 1 1/2 teeth making them stronger for the selected pitch, it puts thrust loads on the case (left to right) which is not what the factory case was designed for. It is much stronger in a radially (up down). Straight cut is the way you want to go to take the left/right loads off of the box.
Instead of using helical, and because we are using a better material to begin with, you can now get a beefier, stronger pitch in a straight cut gear within the same transmission case dimensions. This will take far more load than a smaller pitch helical gear, which is limited to having rather small teeth in comparison in order to be effective. Basically starting from a clean sheet of paper with a whole new concept we were able to achieve what we were looking for.

Helical gears are used for quietness, just like synchromesh transmissions. I, as many of you also probably did as well; used to sidestep the clutch back in the day. Bad idea. Not so bad when the car was stock, but very bad after we started making a bit of power. You should never sidestep, or drop the clutch if you appreciate your wallet. Now that am wiser, I know this. We would actually send shafts through the transmission casings, and if we didn’t we would totally demolish the bearings. Three transmissions in one weekend and I soon changed my driving style. They used to say I could break transmissions by looking at them. Not the best moniker to have.

The straight cut gears, on the other hand, are far better at withstanding this kind of abuse. Had we had this transmission then, I could have saved a lot of money.




Q. I heard straight cut gears whine, is this true?
A. If you have ever heard the reverse gear or some older Ferrari’s, you will recognize the unmistakable sound. The reverse gear on all factory transmissions is straight cut.

At first we anticipated the gearset to be loud. But after it was completed and we had gone for our first test runs, we were pleasantly surprised. After we put the gearset in the street car we realized that they were not as noisy as we thought they were going to be at all. They do whine, but not as loud as we had originally thought they would be. We thought that it would sound like a Ferrari. But it's a bit less exotic. After some daily driving I sometimes forget it’s there.




Q. Does it wear out more if I shift without the clutch?
A. With or without the clutch it doesn't seem to wear any different. Because the dogs are back cut they have a longer service life than a standard straight cut dog as in motorcycle transmissions. We have also made the dogs taller than other dogboxes we've seen and tested on the market. This does two things, more contact area (strength) and also takes longer to wear a big radius into the corner, which translates into more time between having to service it.

***

We recommend changing the oil quite frequently on a dog engagement box, depending on how much shifting you do. We suggest changing out the gear oil every 1500 miles for fresh oil, this will keep your bearings very happy. You will see some particles in the oil after every oil change, this is the nature of the transmission, and is commonplace. This is the reason we suggest changing the oil frequently.
When designing the gearset we wished to have it use as many OEM parts as possible, with as little modifications possible to the existing parts. We were able to keep first gear long enough and still keep the factory reverse arm intact. Not having to grind the reverse lever like other boxes ensures reliability. Also the stock rails and stock forks have been adequate when used with our transmission. If you use good quality new OEM forks you should see a 2 year racing service life on the factory aluminum forks.

No viscous is needed anymore, and the transfer case output shaft is retained by roll pins in the spool. Less rotating mass means better shifting and less inertia.

***

Only place that I've found that sells Honda trannies with dogs is http://www.gear-speed.com

 

Dax, your avatar actually freaks me out...

 

What's freaky about it? Many people tell me I have a great smile.