The most economical transmission solution I have come up with is as follows. 1990-1992 core trans for $100-$200. New synchros, and intermediate shaft bearings. I also clean the gears up. Rinse and repeat.

I've found that the best increase in longevity for me came when I switched to 85w-140 gear oil, and stopped doing back to back 3-4 pulls.

twicks69 said:

You should seriously be listening to what he is saying. We are trying to help you. We have significantly more experience than you. This is not "hatin", I was brought up to help others, not jealousy of someone else's abilities.

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Tim I am no fool I know what I am doing. The only freedom we all have on these boards is to build our cars the way we like I read all others approach and I see nothing but failures and disappointment I am not following that route. I feel confident about my approach all I get is what you're doing is a waste of time money. How can you say that when you never tried it wpc. I have and I know it work. Just so you know it does strengthen cast aluminum.

Ooook dude, I won't offer advise or help then.

Good luck with your project!

Your expectations aren't realistic. Success with the awd trans is measured in how much use you get out of it before it breaks.

To expect the first awd transmission you build to be better than any other transmission built for them, by people with decades of experience is also unrealistic.

What you'll find is that using the best parts, treatments, and meticulous setup will result in a trans that is on par with the best units available. They still break.

I never said it wasn't going to break but I am sure not going to follow a route that is known to break that's foolish.

Maybe i missed it, but why not dogbox?

I wasn't "hatin" on you. Just giving you my experience. I was just surprised you went with the Evo III 3/4 and not the HD 3/4 setup. Also if I missed it are you staying with the 3.909 diff gears?

keltalon said:

I never said it wasn't going to break but I am sure not going to follow a route that is known to break that's foolish.

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Everything you are doing has been done before. There are no routes with stock parts that haven't been done. They all break.

For all you are spending in money and time, you will be in the ballpark of the boldt mechanics gearset. Last time I checked it was 1550eu for 3rd, 4th, both intermediate shaft gears spline fit onto your intermediate shaft, and your center diff housing fitted with a straight cut gear.

Kels,

I can tell you with absolute certainty that the only post manufacturing treatment that you can do to help the gears is shot peen them. However, I'm not entirely sure that anyone can actually do it right. Different applications need different levels of shot peening. It appears that this is found by cut and try.

bastarddsm said:

Kels,

I can tell you with absolute certainty that the only post manufacturing treatment that you can do to help the gears is shot peen them. However, I'm not entirely sure that anyone can actually do it right. Different applications need different levels of shot peening. It appears that this is found by cut and try.

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This is what wpc is its a micro shot peen process the other treatment

89Patches said:

I wasn't "hatin" on you. Just giving you my experience. I was just surprised you went with the Evo III 3/4 and not the HD 3/4 setup. Also if I missed it are you staying with the 3.909 diff gears?

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Its all good didn't mean to use the word too loosely. Yeah I am for know staying with the 3.909. When you say HD 3/4 which gears are you referring?

donniekak said:

Everything you are doing has been done before. There are no routes with stock parts that haven't been done. They all break.

For all you are spending in money and time, you will be in the ballpark of the boldt mechanics gearset. Last time I checked it was 1550eu for 3rd, 4th, both intermediate shaft gears spline fit onto your intermediate shaft, and your center diff housing fitted with a straight cut gear.

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Donnie I am not saying its new just haven't seen much transmission wpc treating around here. Where can the boldt gears be purchased?

keltalon said:

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Donnie I am not saying its new just haven't seen much transmission wpc treating around here. Where can the boldt gears be purchased?

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I contacted him through the dsmlink forums. But he's also on the Facebook.

Lots of people have tried all the surface treatments. Even at their most effective they are still only treating the first few thousandths of a very small gear. From everyone I've talked to you can get an extra 20% strength increase with them. This is actually amazing, but remember you are adding 20% to a gear that was rated around 250ft/lbs to start with.

I’m not sure what to make of the true effectiveness of all the treatments, as I have never used an untreated gearset or preformed a back-to-back test. Various engineering papers suggest they are effective and increase longevity. But the problem with surface treatments is just that—they only treat the surface of the gear. The exception would be cryo. 3rd and 4th gear strip the teeth just at/below the rootline. Gear design engineering principals would also imply that the Evo III 3/4 gears are not as strong as the L91-E92 3/4 gears or 90’ (strongest). However, the Evo III 1st gear and input shaft is advantageous. The Evo III 1st gear has the largest root radius and most meat under the gear teeth before being undercut and isn’t stupid short. If you’re going to run the Evo III 4th gear make sure it is the updated billet gear from Mitsubishi and not their old stock. That gear is less undercut to fit the bearing on the shaft and its material is superior to the Mitsu proprietary 4135H (cast) gear steel. The other thing to pay attention to with new gears from Mitsu is the witness marks left on the gear from the hobbing & shaving operation. Some batches of gears are just bad in this regard and are guaranteed to fail (sooner)—I sent a set back and ordered another because of this. These marks may be seen below the region of the teeth that is shaved and are the main place where cracks initiate when the gears are overloaded.

I am currently on transmission #7. I am making various changes in the off-season so I recently pulled my trans apart and it is showing the classic signs of fatigue. This is after 3,700 miles and 25ish passes at the strip. This trans was assembled w/ new HD L91-E92 3/4 + all treatments, detailed, etc. So I’m putting that one aside. Going to run my last “built” spare which has a welded c-diff, which sucks for the street. After this one strips I am switching to the Boldt Mechanics 3/4 straight cut gear setup & TMZ chromoly cross-shaft. Ever since moving to E85 and crossing the 500 ft. lb. threshold I have had a hard time keeping a trans in my car for any reasonable amount of time. Most have been catastrophic failures—including the case. There are 2 main failure modes—there is tooth breakage from excessive bending stress (function of Brinell hardness) and there is breakage from excessive contact stress. Sometimes a gear tooth may not break from bending stress but rather can develop pits in the tooth face due to high contact stresses fatiguing the surface by compression. The contact pressure is intensified near the pitch circle, where the contact is pure rolling with zero sliding velocity. The treatments, even WPC, cannot overcome the small face width of these gears (3/4 in particular) when you start making real power and simply become severely overloaded, fatigue, fail and destroy everything, in short order. Many in this thread have experienced this more than once, with less power than the OP. Many more have parted out their cars or turned down the power or switched to an auto trans (lame ) because of constant failures.

Keltalon, considering your car makes 801/608 ft. lbs. at the wheels, I would highly recommend inspecting your trans/gears right around the interval Bastarddsm alluded to. It sucks to throw a rare trans with all the upgrades you have done in the garbage at the same interval most change their oil. Just looking out. With 600 wtq, the most effective solution over time is the Boldt Mech. setup (IMHO) or maybe what Donnie does…really depends on how often you use the car and how willing you are to constantly spend the time, energy, down time and money to deal with the inevitable failure after a ridiculously short time. Hoarding nice spares is not as easy these days and many of the most desirable stronger OEM parts are now obsolete…the L91-E92 HD 3/4 DSM gears w/ HD hub and slider is the best/strongest readily available new. Just sharing some insight based on my research and experience—I sincerely like your awd build and best of luck with everything.

I really hope that someone gets a boldt setup. I want to see one. Anyway I'm working on yet another option that fixes a lot of out issues in one swoop. But more on that when I make more progress.

Lots of Evo guys run Boldt gears. Check 4gtuner.com - I think I've seen a couple people there with them.

mavericktsi83 said:

I’m not sure what to make of the true effectiveness of all the treatments, as I have never used an untreated gearset or preformed a back-to-back test. Various engineering papers suggest they are effective and increase longevity. But the problem with surface treatments is just that—they only treat the surface of the gear. The exception would be cryo. 3rd and 4th gear strip the teeth just at/below the rootline. Gear design engineering principals would also imply that the Evo III 3/4 gears are not as strong as the L91-E92 3/4 gears or 90’ (strongest). However, the Evo III 1st gear and input shaft is advantageous. The Evo III 1st gear has the largest root radius and most meat under the gear teeth before being undercut and isn’t stupid short. If you’re going to run the Evo III 4th gear make sure it is the updated billet gear from Mitsubishi and not their old stock. That gear is less undercut to fit the bearing on the shaft and its material is superior to the Mitsu proprietary 4135H (cast) gear steel. The other thing to pay attention to with new gears from Mitsu is the witness marks left on the gear from the hobbing & shaving operation. Some batches of gears are just bad in this regard and are guaranteed to fail (sooner)—I sent a set back and ordered another because of this. These marks may be seen below the region of the teeth that is shaved and are the main place where cracks initiate when the gears are overloaded.

I am currently on transmission #7. I am making various changes in the off-season so I recently pulled my trans apart and it is showing the classic signs of fatigue. This is after 3,700 miles and 25ish passes at the strip. This trans was assembled w/ new HD L91-E92 3/4 + all treatments, detailed, etc. So I’m putting that one aside. Going to run my last “built” spare which has a welded c-diff, which sucks for the street. After this one strips I am switching to the Boldt Mechanics 3/4 straight cut gear setup & TMZ chromoly cross-shaft. Ever since moving to E85 and crossing the 500 ft. lb. threshold I have had a hard time keeping a trans in my car for any reasonable amount of time. Most have been catastrophic failures—including the case. There are 2 main failure modes—there is tooth breakage from excessive bending stress (function of Brinell hardness) and there is breakage from excessive contact stress. Sometimes a gear tooth may not break from bending stress but rather can develop pits in the tooth face due to high contact stresses fatiguing the surface by compression. The contact pressure is intensified near the pitch circle, where the contact is pure rolling with zero sliding velocity. The treatments, even WPC, cannot overcome the small face width of these gears (3/4 in particular) when you start making real power and simply become severely overloaded, fatigue, fail and destroy everything, in short order. Many in this thread have experienced this more than once, with less power than the OP. Many more have parted out their cars or turned down the power or switched to an auto trans (lame ) because of constant failures.

Keltalon, considering your car makes 801/608 ft. lbs. at the wheels, I would highly recommend inspecting your trans/gears right around the interval Bastarddsm alluded to. It sucks to throw a rare trans with all the upgrades you have done in the garbage at the same interval most change their oil. Just looking out. With 600 wtq, the most effective solution over time is the Boldt Mech. setup (IMHO) or maybe what Donnie does…really depends on how often you use the car and how willing you are to constantly spend the time, energy, down time and money to deal with the inevitable failure after a ridiculously short time. Hoarding nice spares is not as easy these days and many of the most desirable stronger OEM parts are now obsolete…the L91-E92 HD 3/4 DSM gears w/ HD hub and slider is the best/strongest readily available new. Just sharing some insight based on my research and experience—I sincerely like your awd build and best of luck with everything.

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Well I do have a set of the HD 1990 gears,center diff and intermediate shaft.

Well after doing some more reading I have decided to use the 1990 hd gears instead of the evo 3 gears and double synchro. I have all the components mention above to make the swap. Intermediate shaft, Center diff and the 3rd and 4th gears. I read a post by bastard dsm somewhere last night about the evo 3 being weaker can't find the post now but he gave a very good explanation as to the difference and the reason for the evo gears being weaker maybe he will chime in.

As far as Boldt gears I am very interested and will definitely get them down the road my plan is to get a spare transmission and start the process. I have reach out to him on facebook just waiting on current pricing. Thanks guys for all the good recommendation! In the mean time I will see just how long the 1990 hd gears will hold up. Still getting all the treatments done on them just so I know .

People say late 91-92? I have 2 91 transmission apart (3rd is in my DD) right now, all my 91's share the ctd gear profile with the 90 and have the aluminum 5th/rev fork. From what I've gathered they both have the "HD" gears the 90's have? I was planning to build a nice trans out of the 92 because the ctd diff is no longer available for the 90-e91. So to build a decent trans I should take the hubs/sliders/gears from the 90 and mount them on the 92 input/intermediate.

Interesting information here I've been learning more about transmissions and differences Jon at tre tre about early 1990 transmissions differences and making one out of the two I had.

It appears that boldt gears are taking a good bit of punishment , 9sec run after run is not to shabby for a synchronized gear I am sold!

Is Boldt setup just straight cut gears?

It's a straight cut 3rd, 4th, cd. Uses stock everything else.

Like I've mentioned in previous threads, to get any real strength gain you need more face width on the gears. Which doesn't happen with the boldt gears.

Going to a better material and increasing the pitch only helps the brute strength incremental amounts. I suspect that the fatigue life of these gears isn't a whole lot better. Your never going to get away from the face that the 3rd gear on the intermediate shaft is subject to reverse loading. That cuts it's fatigue strength in half.

There are a few guys out east going 9 after 9 after 9 on a oem gear set.

I was about get a straight cut gear 1st ,2nd, 3rd ,4th and syncro 5th and resevere trans from dog Box transmission in 2009. They were going 9.4 in 2007. But all the shops, associates, and friends who go fast as hell said it was a waste. But I knew they were just ignorant. I was going to get the gearset shotpeened and then cryo'd. I know for a fact the places I use for treatment would increase the gear strength. I look forward to kels trans. It may take some messing around with but in the end I know it will be bad ass

Adding extra Dowell pins to the case will also help strengthen the case and address the flex issues as well Kels.

spoolin ddub said:

I was about get a straight cut gear 1st ,2nd, 3rd ,4th and syncro 5th and resevere trans from dog Box transmission in 2009. They were going 9.4 in 2007. . I look forward to kels trans. It may take some messing around with but in the end I know it will be bad ass

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Those were oem mitsu gears faceplated by liberty... Also kels trans will be just like every other dsm trans in a high power car. Living on borrowed time. All the treatments are going to do is buy him an extra pass or two.

10's or bust said:

Adding extra Dowell pins to the case will also help strengthen the case and address the flex issues as well

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No. There's not much of a case flex issue. At 1000ft*lbs in first gear theres only about 10000lbs of shaft spreading load. That's only about 5-6000psi on the cases. The yield strength of A356 in the annealed state is 12000psi, so we are at half that, at an absolute worst case.

bastarddsm said:

Those were oem mitsu gears faceplated by liberty... Also kels trans will be just like every other dsm trans in a high power car. Living on borrowed time. All the treatments are going to do is buy him an extra pass or two.




No. There's not much of a case flex issue. At 1000ft*lbs in first gear theres only about 10000lbs of shaft spreading load. That's only about 5-6000psi on the cases. The yield strength of A356 in the annealed state is 12000psi, so we are at half that, at an absolute worst case.

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I find this amusing. everyone or more know now liberty face plated dogbox trans. But...how many knew that's who did it back then? as in 2008-2009ish. I did.

Gears are going to break no matter what but a lot of issues are because of the way people drive on top of the hp. But if he gets the right treatment setup. I say setup because it will take more then one form of treatment. The trans will last way longer then a pass or two. I've seen drag tractor gear parts that scuff after one or two passes get treated and look new after a year. so It depends on what you get done and who is doing the treatment

spoolin ddub said:

Gears are going to break no

if he gets the right treatment setup. because it will take more then on form of treatment. The trans will last way longer then a pass or two. I've seen drag tractor gears parts that scuff after one or two passes. get treated and look new after a year. so It depends on what you get done and who is doing the treatment

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Scuffing is different than ripping the teeth off at the root. If they were just scuffing it was an oil, or surface hardness issue.

The treatments do help. But remember these gears were designed for a car with 200hp.