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09-22-2008, 11:26 AM | #1 |
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5mt case reinforcement is go
While the 5mt case is probably not the main issue in seemingly high failure rates, the aging case design does seem to be a contributing factor. In regards to weak points, I've highlighted some areas that could be suspect.
My products will address these weak points by fastening a large 1/4" thick steel plate into all major front and rear transmission bulkhead bolts. Bolts with a higher-than-factory rating will be included and will allow for a marginal increase in bolt torque specs and huge increase in fastener rigidity to clamp everything together a bit tighter than possible with the factory bolts. There will also be an additional tubular front diff housing brace available. These parts are being released under the brand name "Nighthawk Automotive Engineering." Basic info: Material: 1/4" Steel plate, class 10.9 bolts featuring 130,000psi yield strength in 8mm and 10mm diameters. Solid steel rod on the diff brace. Models: Reinforcement Plate: 2002-and up WRX. Diff brace: 2002-2005 WRX (looking into compatibility with 2006+) Target demographic: All applications from stock to heavily modified. These would be good products for additional bracing on a stock transmission, and they would be great foundational/supporting mods to compliment an aftermarket gearset install. Availability: Initial production runs of 5-10 units per week, though this could probably be increased quickly if there is enough demand. Developement status: Phase: Final design complete for reinforcement plate, 1st production run of 5 units complete. Planned release: January 2009. Other items: -Working with a Nasioc vendor on a distribution plan -All materials and hardware have been sourced for small-scale production. -Planning on new affordable shift bushing designs released under Nighthawk name in solid aluminum or brass and possibly roller bearing forms for competitive driving applications. I want to make it clear that this product is probably not going to single handedly allow you to beat on your transmission like a rabid gorilla without breakage. The idea here is to strengthen some weak points of the 5mt's case design. It's always good to use stronger hardware and reinforce obvious weak points to make the transmission more durable as a whole, and this will likely be most beneficial when complimenting any "upgrade" gearset for above-stock power output (LGT, STi 5mt, MFactory, PPG, etc.). I expect the difference to be more noticeable as power levels increase. Feel free to ask any questions, for more info on these products, visit: http://www.nighthawkautomotive.com Production Reinforcement Plates: Production Driver's side diff brace:
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Last edited by jhargis; 02-05-2009 at 02:30 PM. |
09-23-2008, 03:08 AM | #2 |
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Corrected release date
Oops... Had a typo on the release date. Edited: Should be Mid-late November 2008, not 2009 .
I apologize for any confusion. I've been so busy lately that I must have forgotten what year it is |
09-25-2008, 12:41 AM | #3 |
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Design update:
Based on some input from a member that cracked his case at the bearing directly behind the ring gear side of the front differential, I'm also working on a separate tubular reinforcement that will run from a front bulkhead bolt to one of the bell housing bolts. It will be bolted to the driver's side diff housing at a non-threaded 8mm boss in the case... I made and successfully tested a self-tapping 8mm/1.25 bolt that will be included with the add-on reinforcement for ease of installation since this boss will have to be threaded. This should shoulder a lot of the load at the side of the case generated by the ring and pinion's tendency to "push" each other apart. The prototype should be ready to go and shipped out for testing in the next few days. This part will definitely be installable with the transmission in the car. Last edited by jhargis; 09-25-2008 at 12:49 AM. |
09-26-2008, 02:00 AM | #4 |
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Diff Brace Photos
Alright, I just got finished with a prototype front diff brace to address issues with the case actually cracking under a high horsepower application.
I am still modifying the main reinforcement design on the other side of the trans and will have some pics available as soon as it's done. Everything is coming together quite nicely Underside of the Prototype brace: From the top: Self-tapping bolt that threads this boss, which is normally not threaded: Last edited by jhargis; 02-05-2009 at 02:22 PM. |
09-26-2008, 02:10 AM | #5 |
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interesting... any proof that this will help or only speculation?
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09-26-2008, 02:22 AM | #6 |
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That middle bolt location is right next to where xdrian's case cracked. I got my spare case open and sure enough the support is very sparse there. While the bottom side of the case housing is a fairly beefy curve, the top is flat and not very well supported, so this brace will tie that area into the much stronger front bulkhead and bell-housing/engine block bolt locations.
Basically, the ring gear & diff carrier are being shoved into the driver's side of the case by the pinion gear... This should help to resist flex in that area. I'm not too concerned about the passenger's side of the diff housing as it's not seeing nearly as much force applied by the ring & pinion. This would probably be well complimented by the main reinforcement, as that will tie into the other side of that rear 10mm bolt. It will be going on xdrian's new case. He's saying that he's putting down a 10.8 @ 128, and with the busted case, I'd believe it. While it has yet to be tested, I'm pretty confident that it will help out. When a case actually cracks, it seemed to me like a logical step to add a steel reinforcement at the section of webbing that failed. But I guess we'll see how it holds up Last edited by jhargis; 09-26-2008 at 03:02 AM. |
09-26-2008, 09:56 AM | #7 |
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09-26-2008, 01:22 PM | #8 |
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I am definately interested in seeing more info on this piece - more along the lines of will it actually work and help. I understand where you are coming from, but WHO can really used this? Drag racers seem to be benefited more by this rather than road racers/autoX.
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09-26-2008, 02:14 PM | #9 |
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Obviously, the more power you're sinking into the trans, the more useful any form of case reinforcement becomes. However, I think any time you can upgrade the hardware that holds everything together and find a way hold to bearings in place more rigidly, it's going to have a positive affect on transmission longevity and reliability. There is not much aluminum holding things together and the 5mt design was obviously not originally intended for this kind of punishment (for the reasons I highlighted in the picture on my first post). The 5mt as a whole is not engineered with a lot of headroom for increases in power, I think even the most seasoned subie gearbox gurus would agree there.
Go to your local junkyard and find an old manual subie... You will find that the transmission in a sub-100 hp 20 year old Subaru is not very different from what's bolted behind the engine of a heavier and wildly more powerful WRX. Will the reinforcement be an end-all fix for th Subaru 5mt? I seriously doubt it. That's why I'm trying to keep it pretty affordable. When there are really clear shortcomings in the case design, it seems silly not to put $100 into stregnthening the foundation of your transmission... And for folks running above stock power and/or expensive aftermarket gears, it seems like a no brainer to me. Time will tell. xdrian is pushing good power and the diff brace will definitely be put through its paces there. Once the main reinforcement is done, a pre-production example will be sent off to Dylan at DS1 to get his impression as well. I'd like to try to find a couple of applications where these parts are punished relentlessly to see how they hold up... I was thinking of making a test fixture to measure deflection at different parts of the case with and without the reinforcements in place... But first thing's first: I want to get the basic design along with fit and finish worked out before moving on to heavy data gathering. Besides, there's no better proof of concept than putting a part in its intended environment and seeing how it performs under real-world conditions. If xdrian's case hold up with the brace installed, it doesn't prove much right off the bat, but it would provide compelling evidence to go into further testing. Last edited by jhargis; 09-26-2008 at 02:27 PM. |
09-26-2008, 02:27 PM | #10 |
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Would rolling my case with duct tape do anything? Im curious to see if this will help or not. I see these selling. pretty damn well. But the problem with this product is that its speculation that it will help (if the true reasonf or breaking gears is case flex.)
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09-26-2008, 03:08 PM | #11 |
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Unfortunately duct tape does not have a very high tensile stregnth. But it would be an inexpensive option!
As with any system, catasprophic failure often has a lot of contributing factors. A weak case is probably a secondary factor really. Gear seperation from shaft flex is probably the main factor in my opinion. Stronger shafts and stronger gears make an immediately noticable difference here. However, seperation between the gears will be greater if the structures that hold the bearings which in turn hold the shafts are allowed to flex. The concept goes like this: Gear teeth are wedges, and they naturally will try to seperate under load -> This force causes flex in the shafts on which the gears ride. There is a tiny amount of play in any bearing and the shaft will flex until that play is taken up -> At that point the flexing shaft will impart force through the rollers or balls of the bearing into the outer race of the bearing -> If the structure that holds the outer race is not rigid enough to resist this force, the structure will become slightly distorted in shape and the bearing itself will change position with this distortion instead of resisting shaft flex. By distortion, I'm talking maybe some thousandths of in inch in dimensional change. But that's a lot in terms of change in gear lash. By limiting this distortion, you are limiting the amount of movement in the bearings which in turn is limiting the amount that the shaft is allowed to flex. Last edited by jhargis; 09-29-2008 at 03:16 AM. |
09-26-2008, 04:32 PM | #12 |
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Not trying to crap on your thread or anything, but my take on the situation is that the ONLY 5 speed trans' that will benefit from this is the guys running some beefy ass straight cut gears. Even with MFactory and RA gear sets - the problem is still strength of the actual gears. I blew my 3rd gear in my trans (and my stock gears were cryo treated and shot peened as I lost a set previous to that set.), so they were replaced with RAs (the original ones that were still decent). When everything was pulled apart - the case was still fine, and this is after it's 2nd gear set that blew up in it.
I still plan on doing PPG straight cuts in my gear box, but I am trying to make my RAs last as long as I can. So, I was wondering if you were looking at the situation of how this could make the gears actually last longer? Given that the aluminum used in the trans cases sucks, it seems that cases cracking isn't nearly as common. Do you think that these braces will help prevent gears sliping leading to gears breaking? Or is your stance that the actual cases are flexing allowing the input shaft to move enough to damage the gears? |
09-26-2008, 04:48 PM | #13 |
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I am ready to buy one; the painful part is listening to the negative whining of some people.
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09-26-2008, 07:39 PM | #14 | |
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Quote:
Glad to hear from another potential customer though I really don't mind when people have something negative to say... Sometimes they actually have valid points that lead me to re-visit certain parts of the design and make a better final product. Last edited by jhargis; 09-26-2008 at 07:46 PM. |
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09-26-2008, 08:01 PM | #15 | |
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Quote:
Now back on topic... jhargis - what you said about the stock trans have deflection. How much are we talking about? How much is the case actually moving. I understand that there is quite a bit of force behind the actual gears in the transmission, but if this was a problem wouldn't there have been an easy fix from the factory that would prevent numerous 5 speeds from being blown up? Also - I am just curious on this but how many 5 speed trans cases have actually cracked? I haven't seen any first hand, but obviously creative minds have been inspired by something. I understand your point about helical cut gears causing more bearing deflection, as the whole concept seems like the gears would almost bind together more so than straight cuts anyway... But how often do you see bearing failures in the 5-speeds as well? The most common failure on the gearboxes is obviously the gears themselves. My point is that it's going to be hard to measure any amount of success on these braces as it isn't something common to have go wrong. That and the test car is going to need to throw down some real serious torque. It's obvious that the 5 speed is holding back a lot of people from making some serious power (me being one). But it's going to be hard to tackle a problem like case reinforcement when the only solution to having a decent gearset costs approximately $5000. (PPG gears of course) Hopefully with the release of the Helix gears whenever that will be and creative minds like jhargis those who don the 5 speed may in fact one day be able to have reliable 400AWHP numbers. I wish you the best of luck in designing these braces, and I truly do hope that someone can take actual data of before and after so that there is some serious facts to these braces. If there is any evidence of it helping the gearset last longer - I will for sure pick up a set. As for me - I'll be lurking waiting for a proper solution in order to get serious horsepower numbers on a 5 speed without spending 6 grand. |
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09-26-2008, 08:41 PM | #16 |
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Good input, and I appreciate any insight that I can get.
I'm not sure what the spec for gear lash is off the top of my head for the 5mt (I'll look it up) but I know a lot of domestic transmissions and differentials spec gear lash with a +/- .002" tolerance. And it doesn't take much flex to accomodate a few thousandths of an inch worth of movement. When gears seperate past that tolerance it doesn't neccessarily mean immediate failure either, but it can allow stress raisers and surface cracks to form which propogate to the root of the tooth over time and lead to catastrophy down the road. The bearings do fail... Not regularly, but it's not that uncommon. My front input shaft bearing failed shortly after I bought the car used right around 80k miles. It's certainly not an everyday thing to see a large crack in the case, but the crack uncovers a weak point. Where there's smoke, there's fire. And in aluminum, where there's a crack of this type, there's flex. Subaru did reinforce the case in 1998. I know this because my case was made in 1997 . They went from 4 bolts at the bellhousing to 8 bolts, probably for added torsional rigidity. They also added some material along the top and and bottom, no doubt in my mind for increased torsional rigidity. I've been in manufacturing quality control helping out with R&D and warranty-claim analysis for about 4 years now and have been over this scenario more times than I can count in a couple of different companies: The current design fails too often... so you find a reason and the bean counters tell you to add just enough stregnth so that it doesn't require massive retooling or other major production expenses. Engineers being limited by cost, no new concept there. There is a financial curve involved in this kind of revision. You stregnthen the design such that warranty claim costs do not exceed the money you save by not building it stronger/better. Big limiting factor there. Another big deal to me is the hardware involved... Subaru uses metric class 8.8 bolts to hold this thing together, which is really sub-par. Class 10.9 bolts are far stronger but much more expensive in the 180mm+ lengths needed (about 4-5 times the price of class 8.8 per bolt). So that's an obviously cut corner. Subaru did stregnthen the case to some extent, but certainly not to the level that you would see in a 6mt or any other modern transmission in a high performance car. That would have killed their bottom line in re-tooling costs and production down time. I'd imagine that this was a move made to hold the STi models together until the 6mt was ready for production. They left some very obvious weak points in place. That's where I'm stepping in. It takes some work for a car manufacturer to bring such a potent AWD car to market at a mid-$20k price range. But little things like using class 8.8 bolts instead of 10.9 and staying with basically a facelifted 20+ year old transmission design are what keeps the WRX affordable. Which is fine, that's why the aftermarket is alive and well Remember that when you're building 20,000 or more units of something, an easy $10 per-unit revision means you just lost $200,000 or your retail price goes from $25,995 to $26,005 (example) and 300 fewer fickle Americans buy your car. So nope, they might not have applied what to your or me seems like an "easy fix." That's just a reality in manufacturing. Last edited by jhargis; 09-26-2008 at 10:53 PM. |
09-26-2008, 10:27 PM | #17 |
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I had not realized the bolts were 8.8 either. Maybe you should consider offering the 10.9 bolts to replace the 8.8s for an additional cost. At that point my interest in this kit would only grow more so.
Going back to the bearings though - there could be many factors that would cause bearings to fail, so that needs to be taken into factor as well. It seems like you've got a great start on this project and you've looked into quite a few things. After talking with you about this my interest has grown in what you have to offer. I will definately be looking into this thread as it progresses. |
09-26-2008, 10:50 PM | #18 |
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Yup, they lack any standard markings and they have a corrosion resistant zinc finish (so they look like SAE grade 8 bolts), but if you look up generic bolt torque specs for 8.8's of that size/thread, they match up exactly with the factory torque specs. 10.9 torque specs are a good percentage higher.
Under "basic info" in the first post, you'll be happy to find that Class 10.9 bolts will be included with the main reinforcement at least at 4 bolt locations. They're kind of expensive for bolts, but I've factored those into the price 2 x 8mm/1.25 bolts that clamp the rear bearings down and 2 x 10mm/1.25 bolts at the front input shaft and pinion bearings. If I can fit it into the base price, I'll try to get some 8mm bolts along the top and bottom in as well, those are in lengths that are much less expensive... at least at the important positions. High grade metric hardware is surprisingly hard to find in the lengths that I'll need here in the states. Pricey too, I can see why Subaru went to a lower grade. Once I get the design and tooling for the main reinforcement hammered out, I'll likely look into the details of putting together an entire class 10.9 5mt bolt set. Shouldn't be too terribly expensive, and it would be sort of silly to use the crap factory hardware on a rebuild or gear set install if I can make the 10.9 stuff available for a reasonable price. Glad to hear your interest is growing. We'll see how the diff brace brace holds up in real world testing, and I'm anxious to get a pre-production main reinforcement made to send off to Dylan @ DS1 so I can get his expert analysis. Last edited by jhargis; 09-26-2008 at 11:41 PM. |
09-26-2008, 11:00 PM | #19 |
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Interesting read and product
SO is there a way to measure the case deflection? If so test your prototype, if it works, they will sell pretty well I think. just a suggestion, when you do decide to measure case deflection, do it on several cars that vary in whp, to get an idea of when/if it actually becomes benefitual. GL |
09-26-2008, 11:22 PM | #20 |
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Well to give you guys an idea of what the main reinforcement will look like, here's the revised bolt pattern template. The reinforcement itself will look similar to this in shape, but will have a hole near the middle large enough to clear the speedometer sensor and will have steel stand-offs between it and the case.
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09-26-2008, 11:33 PM | #21 | |
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Quote:
So... Next question: Is anybody willing to donate an already broken transmission? |
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09-26-2008, 11:44 PM | #22 |
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I have a couple of transmissions laying around.
I may be willing to donate one for a pototype reinorcement. |
09-26-2008, 11:49 PM | #23 |
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All I would need is the front half without the center diff housing/rear, to ease shipping costs. I wonder how much shipping would be on that? Sucker is pretty heavy. I'll see if I can't get something together here... If not, I might be getting in contact with you to see if we can arrange something.
Thanks. |
09-27-2008, 12:49 AM | #24 |
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The reinforcement plate isn't the nicest looking blingy piece, but for something you won't see function is definately better than form.
As for the hardware - I meant to ask you where you are getting the 10.9 grade hardware from. I find it extremely hard to find a decent supplier locally to me. The best I've found is STILL Ace. As for having Dylan take a look at the final product - that's a great idea. He builds more transmissions than anyone I'd think. I'm looking forward to seeing what he has to say about the reinforcement kit. |
09-27-2008, 01:19 AM | #25 |
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Haha, no that template falls far short of bling... That will be the base for the production jig. The part itself won't be much more fancy but I'll make it look at least slightly more impressive. However, the basic fitment and layout of the main reinforcement will be the same. I just posted the pic to give folks an idea of how it works.
As for sourcing the hardware... well... Trade secret. But I doubt Ace would have class 10.9 bolts in 200mm length, few places in the country do. Let's just say it took me some days and lots of phone calls to find . You won't find them on the shelf anywhere... I'm looking at 1-2 week lead times on the bolts as it is, as standard sizes usually only run up to 120mm-140mm through most suppliers. |
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