bearing change on yzf750/thunderace wheel

billy budge · Post by **billy budge** » Sun Jan 20, 2008 7:05 pm

To all you blokes that use the yzf750 or the thunderace rear wheel, i need your input please if you have ever changed the wheel bearings yourself.

Not done it before on this wheel but through a moment of stupidity and not measuring the recess before i put the new bearings in, once they were seated properly they were about 2mm proud of the recess on the sprocket carrier side. Ive always known bearings to sit sub flush but after thinking there must be some debris or a burr behind it i knocked it back out again, then after i measured the recess i was deeply pissed orf!!!!
There is a double recess if you like and didnt know why, cant see what would go between the bearing spacer and the bearing and nothing was there when i took the old bearings out originally but now i wanna know for sure if this is the case.
The bearings are correct and measure ÃƒÆ’Ã‚Â¸52mm and 14.95mm thick, the first recess is also ÃƒÆ’Ã‚Â¸52mm but only 12.95mm deep???
Then it steps up by approx 2/3mm and the second recess is ÃƒÆ’Ã‚Â¸47mm and 5mm deep, sorry this is abit lengthy but i dont want to bollocks up anymore bearings by using guesswork. I did try the sprocket carrier on afterwards and it seemed ok, but again with that ive got nothing to compare it too and couldnt remember how flush to the hub the carrier sits.
If anyone has got a picture of the sprocket carrier on the wheel then id be eternally grateful and i may even buy all your drinks at the avebury meet!!!!

Cheers peoples.

honkdawillydahonk · Post by **honkdawillydahonk** » Sun Jan 20, 2008 7:33 pm

Billy,

Get one side seated correctly, then measure the length of the middle spacer and the other bearing. This will give you a ball park (within a mm or so) of where the other bearing should be when seated correctly... Once assembled the bearings should turn freely and the middle spacer should be lightly retained (ie not flopping about inside)

Hope this helps....

billy budge · Post by **billy budge** » Sun Jan 20, 2008 8:48 pm

Cheers Ad,

Yeah mate that helps, simple but effective!!! Is there a specific tool for knocking the bearings in, i just used the old bearings as a drift...seemed to work ok???

Quan-Time · Post by **Quan-Time** » Tue Jan 22, 2008 1:10 am

yer, the older bearings make an awesome way to push the new bearing in.

Saying that, I usually make a bearing punch if i dont already have one for that size. But having access to a lathe helps.

You want to punch on the OUTTER part of the bearing, not the inner. So a piece of tube is quite often the best way.

steve speed · Post by **steve speed** » Tue Jan 22, 2008 1:43 pm

or try a socket of the right size

billy budge · Post by **billy budge** » Tue Jan 22, 2008 8:40 pm

Cheers for the pointers chaps.

While we are on the bearings subject, i should be getting round to the trx front wheel bearings this weekend and need some advice please.

The thunderace rear wheel bearings look identical whereas the trx front bearings are completely different to each other in looks. Although they are both 6203 code numbers, one is 6203ZZCM and t'other is 62032RSCM. One has a red rubber strip around the middle and one is just all metal looking, does anyone know what one goes where as im assuming as they are different it matters what side they go?? Cant find anything in the yamaha manual or the haynes to confirm that it matters or not.

Cheers.

steve speed · Post by **steve speed** » Tue Jan 22, 2008 8:57 pm

i think that 62032RSCM. refers to the rubber seal which i think is correct for both sides

billy budge · Post by **billy budge** » Tue Jan 22, 2008 11:10 pm

By that then mr speed, do you mean that my main man at yamaha has sold me one duff bearing???

The yamaha manual says they should be the same numbers.

youngy · Post by **youngy** » Tue Jan 22, 2008 11:19 pm

according to oemmotorparts the bearing number is B6203RS on both sides of the front wheel. there is also an oil seal on the right hand side. maybe you've been sold a bearing with an integral seal for that side???

http://www.oemmotorparts.com/oem5.asp?M ... TRX-850_bi

billy budge · Post by **billy budge** » Tue Jan 22, 2008 11:27 pm

Cheers marty, gonna check with yamaha tomorrow and see what the score is.

The bearings i got sold were made by koyo and have K62032RS on the box and then also the other 2 numbers i mentioned earlier????

Looking on ebay at sets and they are identical, i bought the oil/grease seal separately so im buggered if i know whats happened!!!

steve speed · Post by **steve speed** » Wed Jan 23, 2008 1:42 pm

you can fit those bearings just make sure that you fit the one with no rubber seal behind the oil/grease seal ,i think that's the speedo drive side ..koyo are good they are a c3 fit ,which is good ,but remember as quan said dont bash them in with the center use a pipe or a socket on the outer ring ,, warm the wheel up first and it will be a lot easier

youngy · Post by **youngy** » Wed Jan 23, 2008 2:26 pm

or put the bearing in the fridge overnight

billy budge · Post by **billy budge** » Wed Jan 23, 2008 2:43 pm

Cheers speedy, appreciated.

You boys are all geniuses, how do you discover these pearls of wisdom??

Quan-Time · Post by **Quan-Time** » Wed Jan 23, 2008 3:24 pm

lots of skinned knuckles.

steve speed · Post by **steve speed** » Wed Jan 23, 2008 3:33 pm

mine was mostly picked up at unity spares in castleton in the 70s,bashing lumps of British iron