Vintage Dirt Bike Q & A

i want to put new shaft seals in the rear 1975 mr175 shocks i have. Does anyone know a souce or size for these? Also, what would be the oil weight used stock in these shocks?

The shafts on my MR175 shocks are 12mm. This place has a new seal kit, but it isn't cheap (it's about halfway down the page, on the left side):

http://re-mx.com/cr/cr125_cr250.php

I read an online article by a guy who's rebuilt a bunch of these shocks - I thought I saved it on my computer, but I went through everything and can't find it. If I recall correctly, he unscrewed the seal caps and allowed the fluid to drain out completely, then measured it and used exactly that same amount again when rebuilding. He indicated that too much fluid would blow out the seals, and too little resulted in no damping around full extension. I believe he refilled with either 3W or 5W shock oil.

I wish I could show you the article. Damn, I keep everything, don't know where it went. Maybe re-mx can point you to it, or send you a copy.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Think I found it, but it dates back to '04,his name is Jerry-
Your shocks are rebuildable. I sell seals for $12 a set but I need to know if they are the early 10mm shaft or later 12.5mm shaft. I recommend 5w oil nothing heavier seems to work. You can do it yourself they are not that complicated. The tricky part is filling them with oil. Too much and they lock up mid stroke, too little and they run out of dampening at the top of the stroke. Contact me at mailto:elsinorestuff@qwest.net if you want seals or if you want me to rebuild them for you.

I got a set of poly seals in 1"od x 1/2"id x 3/8" height. They fit fine and work great for the 12mm shafts. For the 10mm shafts, the 3/8"id seal fits just right. These were about $5.00 each at the local hydraulic shop and they are always in stock. That was all for my cr250m, but aren't these just about the same shocks?

The book I have for the 74 CR250M recommends ATF, which also works just super. 145cc's was the oil volume that I learned after building mine. I followed advice to fill it to the point where there was some open space above the oil line when the shaft was compressed, and when the shocks were assembled they have damping at full extension. That for me ended up being right at 110cc or so. That guideline ought to get in the hunt.

Enjoy,
Jon

I am attempting to rebuild a set of 1979 CR250r shocks and I am looking for parts, the shaft is 12.5mm and the ID of the shock body is 40mm. I would need main seals, o-rings, bumpers and piston rings if possible. Thanks.