Author Topic: 74 DT 250 rear wheel/sprocket  (Read 449 times)

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Offline 2nd Gear

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74 DT 250 rear wheel/sprocket
« on: April 11, 2016, 12:35:20 AM »
My son found a DT 250 (1974) at a good price. While changing brake shoes I noticed a slight wobble to the rear sprocket even thought all the bolts are tight.  Down anybody know if this is normal for this bike.  I'm new here so any help would be great and thanks in advance.

Offline wayne61

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Re: 74 DT 250 rear wheel/sprocket
« Reply #1 on: April 11, 2016, 02:50:25 AM »
Hello Mate
Not sure about 74 DT's specifically, but in general wobbly sprockets are not recommended.
I'd guess it was bent and ready for a scrap bin.
Go soothingly on the grease mud, as there lurks the skid demon.

GRIP AND RIP CRAIG AND CHRISSO!!!

Offline 2nd Gear

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Re: 74 DT 250 rear wheel/sprocket
« Reply #2 on: April 11, 2016, 03:46:12 AM »
The sprocket is straight but the whole assembly has a little play in it.  The sprocket bolts are tight, but there is a little play in the whole assembly.

Offline Martin I Henry

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Re: 74 DT 250 rear wheel/sprocket
« Reply #3 on: April 11, 2016, 04:08:16 AM »

Quote
The sprocket bolts are tight, but there is a little play in the whole assembly.

I expect the assembly is supported by a rubber 'cush drive'. Probably normal.

Post-up some photos.

Cheers,

Dave R.

Offline Guilly

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Re: 74 DT 250 rear wheel/sprocket
« Reply #4 on: April 11, 2016, 07:29:34 AM »
Good day Second Gear, yeh that is pretty nornal for that model bike with some distance covered and being a 74 its probably has covered quite some distance. The rear sprocket is a rubber cush drive system with rubbers inside the hub. The sprocket bolts to a boss and this slides onto the centre hub and into the cush drive and is held there by a large circlip. When new the rubbers are not worn and neither is the groove the clip locates in but of course they both wear and play or movement is the result and to some extent is normal. Check the grove and the circlip and determine if they are still servicable ie is there enough wear and "play" for that clip to come off if you think so you may have to look for a replacement rear wheel. Replacing the cush would probably help.
I have had the same problem when I was in my 20s on a bike that was up around 30k covered. My repair which worked OK was a bit extreme was to dill through the boss and the hud and run bolts through ( 6 of them I think, maybe 8mm) because the groove on my hob was totally shot. This was a 74 360A, same rear wheel. Not the prettiest fix but it worked.
Cheers Guilly
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Offline 2nd Gear

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Re: 74 DT 250 rear wheel/sprocket
« Reply #5 on: April 11, 2016, 08:20:56 AM »
OK thank you.  The play seems minimal, but not used to this type of rear wheel/hub so it seemed abnormal to me.  Thank you again for your help

Offline dont

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Re: 74 DT 250 rear wheel/sprocket
« Reply #6 on: April 11, 2016, 06:03:02 PM »
There can be quite a bit of wear before it gives a problem I think. I thought my DT2 cush drive was giving problem due to this wear and used some 1/2 mm aluminium sheet to make a kind of shim/bush that got it nice and snug again with little play.
It turned out the problem I had was a loose flywheel and sheered woodruff key.
What goes up must come down, unless you broke a 'rod 😞

Offline 2fITy.J

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Re: 74 DT 250 rear wheel/sprocket
« Reply #7 on: April 11, 2016, 06:19:21 PM »
Yep, hate when the cush drive hardens and condenses...leaving you with a slight delay with gear changes and a horrible jerky ride at a cruise speed.

Although unavailable new,  some NOS items may still remain...try searching the part number... Yamaha 275-25364-00-00 DAMPER Ebay can be a good source for NOS parts.


If no joy, there should be some used ones at a bike wreckers, the part was fitted to these bikes so your search widens somewhat....

1970 RT1 REAR WHEEL
1970 RT1M REAR WHEEL
1971 DT1E REAR WHEEL
1971 DT1MX REAR WHEEL
1971 RT1B REAR WHEEL
1971 RT1MX REAR WHEEL
1972 DT2 REAR WHEEL
1972 RT2 REAR WHEEL
1973 DT3 REAR WHEEL
1973 RT3 REAR WHEEL
1974 DT250A REAR WHEEL
1974 DT360A REAR WHEEL
1976 DT250C REAR WHEEL 250B - C - 400B - C
1976 DT400C REAR WHEEL 250B - C - 400B - C



Cheers,
Chris.
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Offline fred99999au

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Re: 74 DT 250 rear wheel/sprocket
« Reply #8 on: April 11, 2016, 09:22:47 PM »
I reckon a tube of silicone and a couple of fruit shop placcy bags might be in order to take up some of the slack.

Offline wayne61

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Re: 74 DT 250 rear wheel/sprocket
« Reply #9 on: April 11, 2016, 09:40:06 PM »
Shim it with cut up innertube?

(soz 2nd Gear Dude, didn't know old DT's had a cush drive)
Go soothingly on the grease mud, as there lurks the skid demon.

GRIP AND RIP CRAIG AND CHRISSO!!!