DR650 3rd gear blowups

Discussion in 'Thumpers' started by NordieBoy, Jan 16, 2009.

  1. BergDonk

    BergDonk Old Enough to Know Better

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    I've collected a few now and its random. Some exploded gears with all dogs intact, some with missing teeth, you name it. The pitting is in my view unrelated to the breakage failures.

    With respect to even loading of the dogs, I'm told that with 3 or less dogs, the clearance on the shaft is such that after a very short period they all load evenly, unless the machining is diabolical.

    The pitting is mostly related to oil film breakdown, and even the Nova gears are not immune from that, or dogs snapping off. the design is under spec, hence the value of the new complete Nova box to be available real soon..




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    Nova 'A' box vs stock.

    Lots more over on DRR; https://drriders.com/new-wide-ratio-gearbox-t18311.html
    ER70S-2, DR650Pete and procycle like this.
  2. Big Willy

    Big Willy Gen. Italia

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    I agree with you re the pitting not being a factor.

    I wonder what tests have been performed to substantiate the dogs all engaging theory?

    Seems very odd and haphazard to me when the rest of the gearbox is carefully machined and hardened that dogs wouldn't be machined as well?

    Could explain why some gearboxes let go and others don't

    Or maybe it's rider error i.e. not engaging gears properly.

    Just thoughts Steve :1drink
  3. GSXR

    GSXR Trail Rider

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    This fine country was built with hard labour and determination, and has some amazing places top to bottom, east to west.

    This transmission was laboured to death on the way to some of them... DSCI1555 (Medium).JPG
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  4. Big Willy

    Big Willy Gen. Italia

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    Haha...well spotted!

    Good reason for using the 525 sprocket. I know Steve modifies his drive sprockets.
  5. BergDonk

    BergDonk Old Enough to Know Better

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    This one was a mate of mine's that let go in a big way @ 55,XXX kms. Happened on the 2nd 3rd change under acceleration. Locked solid, but he kept it upright. He knew his 520 sprocket was an issue once he spotted it going, but decided to live with it. Gearbox explosion meant it didn't matter.
  6. jjxtrider

    jjxtrider questionable

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    The pitting I've seen on all brands , Yamaha , Kawi , and Honda all have this gear/that gear in some models do it , mainly the ones that are used the most . I feel it's due to cavitation/mini bubble explosions created when the oil is trapped between the teeth as they run against each other , which are close to the same geometry and many oil pumps . But I'd agree it's not the cause of this breakage otherwise it would be common in other bikes as well .


    .
  7. BergDonk

    BergDonk Old Enough to Know Better

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    I wondered about cavitation myself. Others who know a lot more about oil and gears than I do have discounted it though, and pretty much agree its metal to metal due to oil film breakdown. I'm just the messenger.
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  8. doug s.

    doug s. Long timer

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    i am just making a layman's guess here, but i wouldn't be surprised if the gear destruction is caused by lugging the engine in too low a gear, whilst attempting to travel in mucky off road conditions. i wonder how many folks have experience this problem who don't ride off road, or at most ride well-kept fire roads, etc...

    doug s.
  9. gunnerbuck

    gunnerbuck Island Hopper

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    The has been lots of failures while on paved roads, some have happened when slowing to take an exit ramp off the hwy.. There is no real smoking gun as to why, even some low mileage lightly ridden bikes have had the gearbox pop... The failure numbers are pretty pretty small when compared to units sold but the randomness of it means that there is always a small possibility for it to happen no matter how ridden or what model year the bike is... Some guys have had the failure happen on long trips in a remote place where they just abandoned the bike and found alternate means to get home... I rebuilt a friends engine last year that had about 40-50 K on it and the majority of gears in the box had bad pitting, we picked up a lower mileage donor motor to swap bottom ends and the gears in that box had stretch marks, but no pitting.. The bad thing is the locking of the wheel at speed when the gearbox pops, there was a case here where the guy went down after a lockup and skidded off the road, fortunately a vehicle was not coming the other way at the time when he crossed lanes.. There could even be some incidents where riders have been killed due to a gear box failure causing a skid out but it was documented as a rider at fault "losing control" accident..
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  10. doug s.

    doug s. Long timer

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    well, my theory could certainly be hooey. but, i still wonder, even these bikes blowing up on the street - how were they ridden when in the messy stuff? or were many street-only bikes? not certain what the life of mine was prior to my ownership, but it will never see dirt in my hands...

    as far as losing it due to lock-up, i am sure that's a possibility, but it seems more likely to have a serious incident locking up the front wheel, as opposed to the rear.

    doug s.
  11. gunnerbuck

    gunnerbuck Island Hopper

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    These bikes are dual sport so in theory they could spend time in all kind of conditions, messy or clean... Is your point that these bikes should be babied and not ridden as per design? It is likely that a very large percentage of these bikes that are out there rarely see more than just easy gravel roads.. The DR I rebuilt last year with the badly pitted gearbox had seen a lot of varied conditions, including loaded back country travel so it did not have the easiest life..
  12. procycle

    procycle Long timer

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    What strikes me is nobody has reported blowing up the transmission while seriously thrashing on the bike. No blow-ups in the middle of a gnarly hillclimb, No blowups while racing against buddies on a trail, etc. Most reports are "I was just riding along..." or "I just shifted into 3rd gear..."

    Also, most blowups seem to happen at lower mileage. There are LOTS of DR650s out in the world with 70K+ miles on them but most blowups happen prior to 25K miles. To my mind this points to a small percentage of gears with manufacturing (maybe heat treat) defects. The vast majority of bikes without defective gears run forever. The few with defective gears break regardless of how they are treated. If it was really all about riding conditions or accumulated abuse the high mileage bikes would break MORE transmissions, not less.
  13. BergDonk

    BergDonk Old Enough to Know Better

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    The one above that blew with 55,XXX kms was, and always was, ridden hard, not abused, and not lugged. OK one moment, not the next. Ridden by someone I have ridden with on the road, track, enduro competition and trail for 25 years.

    @micko01 's went twice, including the Nova dogs, being ridden side by side with his now wife, @Tan101 on her DR.
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  14. Big Willy

    Big Willy Gen. Italia

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    Definitely some flaw whether in design or manufacture that should have been addressed by now.

    For example...KTM690 has almost double the horsepower with a 6 speed box (that you would naturally think would have to have narrower gears) show no such problems apart from the very rare problem of the countershaft? shitting itself @El Ponkin

    Shame on Suzuki for not addressing the issue. With their substantial career in racing and engineering, you can not tell me that they do not know how to remedy the situation. Maybe the extra cost would affect sales or profit margins?
  15. Lammi

    Lammi Wannabe

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    I had just shifted up to 3rd when this happened...

    56,000k’s
    2001

    FML

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  16. doug s.

    doug s. Long timer

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    "...Is your point that these bikes should be babied and not ridden as per design?..."
    no, and that's not what i said, either. i was wondering if lugging the engine, especially in messy stuff, might be a contributor. if not lugging the motor is considered babying it, then maybe it needs babying?

    doug s.
  17. procycle

    procycle Long timer

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    I think not enough of them fail during the warranty period to force Suzuki to do more.

    Something I've noticed after inspecting a load of DR650 transmissions is that the 3rd gear set *looks* to be made to a higher standard than the rest of the gears. The finish is smoother, etc. This hints that they know there's an issue but are only willing to go so far in minimizing it.

    Also, the gears aren't just narrow but small in diameter. If the transmission shafts were further apart there would be room for larger gears that could carry more load with less stress. But that would mean a complete redesign of the motorcycle.
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  18. Big Willy

    Big Willy Gen. Italia

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    I see your point...:thumb

    So they basically can't address what they know is an issue without a redesign of the gearbox (which must necessitate a redesign of the engine case) which would necessitate a redesign of the motorcycle frame to accomodate the new cases.

    Will be interesting to see long term tests of the Nova box to see whether it holds together although I suspect that the DR650's days must be almost numbered by now.
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  19. gunnerbuck

    gunnerbuck Island Hopper

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    I think Suzuki is working on 1 fuel injected motorcycle that will replace both the DR 650 and 400, maybe something that displaces 450-550.. Let's hope it has a 6 speed gearbox..
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  20. hboehle

    hboehle Adventurer

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    Whether with the Nova set or just OEM, is anyone replacing their gear(s) preemptively, or is general consensus to just ride and hope?

    Purchased used at 4k miles, I ride my DR fairly hard (tight singletrack) but also commute highway and have 11k miles on it now. It has always had a fairly sloppy transmission shifting feel to it compared to other bikes I've owned, but no whining, false neutrals, etc. Do DR trannys typically feel less positive shifting than other bikes, or would this be interpreted as a potential warning for failure? Would hate to find out on my highway commute...