‘Drivetrain Slap’?
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Is it possible your chains stretched in one place causing a tight and loose spot.
Riding BMX you get this happen a lot stopping you from being able to get the correct slack. This only ever happens with cheap / non genuine or chains made by a non reputable maker
Obviously I know this is bmx so I’m not sure how well it carries over but I guess the same principle could get applied
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@SpookDog Cheap chains can cause this as others have said but sounds like you've pushed the boat out running an X-ring chain.
There's a chance your lower chain roller could be fitted upside down; it's by no means obvious and I've seen lots of people fall down this hole on the DTR, it allows the chain to hit the frame's cross member below the swingarm pivot and could also increase its propensity to hit the lower part of the rear chain guide, particularly whilst decelerating.
Spring-loaded chain rollers/slippers were a thing on late 70s/early 80s trials and MX bikes but the pad or roller will wear quickly and running one could cause problems on a bike with as much rear travel as the DTR as chain tension varies so much over the suspension movement.
Chain roller bracket should look like this
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Yeah, I fitted a JT sprocket & X~ring chain set. It’s a great chain. My roller does look a bit worn down compared to your pic. I’ll try replacing it and tweaking the chain again when I fit my new back tire...
Can anyone please link me to a good replacement roller?...
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@SpookDog said in ‘Drivetrain Slap’?:
@HOTSHOT-III
Can anyone please link me to a good replacement roller?...Ditto, one ony ETX looks goosed
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@SpookDog I've always just used genuine ones from Fowlers or Yambits. Worth replacing the plastic sleeve as well. They seem to last pretty well if you degrease and re-lube them when washing the bike or a dash of chain lube whenever you lube the chain.
A lot of MX shops sell aftermarket ballraced chain rollers (basically skateboard wheels) so just a matter of getting one with a 12mm ID the correct width. DirtBikeExpress have a fair selection:
https://www.dirtbikexpress.co.uk/search.php?search=chain+rollers
Yes my top one hardly ever displays signs of use, it's only there to stop the chain slicing through the airbox when the rear suspension is on full compression as you say. In fact when that pic was taken, I'd just swapped the top and bottom rollers as a temporary measure as we were in lockdown! The lower one does a lot more work in normal riding conditions
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@HOTSHOT-III
Cheers, I would much rather have a ball or needle raced roller...If anyone can recommend a good one I’d be grateful. Save me my usually painful learning curve
...Cheers!
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@SpookDog Just measured some NIP genuine parts:
Plastic sleeve
Overall length 28mm
ID 12mm
OD 18mm where the roller fits (25mm) 24mm at the "top hat brim" part which is 3mm deepFoam roller
Overall length 24mm
ID 18mm
OD 35mmA lot of the ballraced aftermarket rollers look like they're designed to be fitted directly to the frame mount using an M8 bolt (although they don't give dimensions which seems a pretty basic oversight for someone selling universal MX bike parts online); potentially not a problem for the upper DTR roller but to use one as a lower one would necessitate either butchering the stock bracket which bolts to the frame or designing and making a new one
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Cheers for the info bud! I did manage to find a few likely suspects. 8mm inner hole and fittable to the nut on my lower mount, as well as being bearing raced. I’ve even found a few spring loaded contraptions that look fitable,(with a bit of finessing!) but I imagine that if they’re in constant contact with the chain that they’d shred the roller PDQ! It’s all food for thought though
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Once I tap a grease nipple into both sides of the swing arm front mount points. Try and find some half decent progressive front springs, get the upper and lower bushes and new seals, I’ll be happy. Have managed to get hold of a dtr200 variable dampening rear shock that I want to try and rebuild as well. I’ll have more faith in the setup at 70mph plus speeds
...I also want to improve the engine mount bolts under the swing arm bolt and at the engine front mount below the exhaust and bottom coolant pipe...
I think my engine may of been shifting about under loads and putting excess pressure on the cylinder head mount. Maybe affecting the gasket seal??!... on
