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View Full Version : 1upfronts new custom clutch



Daddio
06-01-2008, 10:41 PM
On the second race of the year 1upfronts 300r smoked the clutch in a bad way. He said that he wouldn't put it back together until he could find something more durable than the stock set-up. Well after much research we decided that no one makes anything for the air cooled Rs. So he said that he thought that the 78-80 cr 250 shared the same clutch as the 81-84 R. I looked into the prospect of finding out what was available for these. I was able to find a billet clutch basket for the cr 250 on ebay uk. It was quite pricey and took a while to get this guy to ship it to the states.
The next problem was the play where the kick start gear fits into the clutch drive gear. This is important because the clutch bearings fit inside of the kick start gear and the gear actually supports the drive gear and basket. We thought that welding the two together would solve this problem. The drive gear is cast so that limits what you can do as far as welding. So after much discussion with many people we decided to braze the two together. That went pretty well. After brazing we put it in the oven and let it cool down over a period of several hours.
The next problem was that the center of the gear that rides on the bearing had shrunk about five thousandths of an inch and it no longer fit on the bearing. We took it over to a good friend of mine, who is the local Harley guru and millwright, and he honed it back to stock specs.
Now we are ready to join the new basket to the modified drive gear. The new basket came with solid rivet for this task. This would be easy with a rivet press but I don't have one so we had to do it the hard way. The old hammer and bucking bar method.
This new basket uses 300ex clutch plates and the stock hub and steel plates. He bought some cr500 clutch springs for it and as soon as the new steels get here it will be going back together for a trial run then weather permitting we will be taking it to Dirt Country on the 7th for a TF warm up.
http://i39.photobucket.com/albums/e183/lrdunlap/100_0338.jpg
stock basket
http://i39.photobucket.com/albums/e183/lrdunlap/100_0347.jpg
kick start gear/drive gear
http://i39.photobucket.com/albums/e183/lrdunlap/100_0404.jpg
gear brazed on
http://i39.photobucket.com/albums/e183/lrdunlap/100_0402.jpg
finished product ready to go

tecat-z
06-02-2008, 12:11 AM
Very nice. I'm so glad Sprock has given us a chance at new billet baskets for the tri-z. I've said it before, i'd love to have one for my first gen t-3. Seems all of the baskets left are gettin' pretty worn. This will definately be a big deal in the near future for the t-3 and air R's. Oh, and people that don't know Sprock.

dansvan
06-02-2008, 04:22 AM
I was told the CR500 springs are actually softer/weaker than the 250r springs. What have you found out?

Daddio
06-02-2008, 08:02 AM
I was told the CR500 springs are actually softer/weaker than the 250r springs. What have you found out?

He ran them for a while last year and decided to switch back to heavy duty stock one because the 500 ones made it too hard to pull the lever.

300rman
06-03-2008, 01:55 AM
not really understanding what kind of clutch plates are meant to be used with this basket. obviously not stock.

Daddio
06-03-2008, 09:22 PM
:wondering It uses 300ex plates. Actually when you cross reference the ebc part # on dennis kirk the list of other machines that these plates fit it is quite extensive. Since we work at a Honda dealership we ordered them for the 300ex from Honda.:)

Daddio
06-08-2008, 10:16 AM
Well the steels finally got here on Fri. ,had to work yesterday but finally got to put it all together. Things weren't all great at first. With all of the new stuff in there we couldn't get enough action out of the clutch. Hartley had all of the adjustment used up and it was just starting to disengage the clutch. That is not a good thing. So I told him that he should measure the thickness of the new style steels and discs against the the stock ones. He found that they were 2.5 mm thicker than the stock stuff. So I went over to the shop and put a few spot welds on the end of the clutch rod to make it a little longer, then I filed it down then carefully sanded it down until it was 2.5mm longer than stock. Then I polished the end with an extra fine sharpening stone so it wouldn't cause any wear on the clutch actuating arm. Got it back together at about 10:30 last night and readjusted everything. The adjustments are all right in the middle now like they should be and the clutch feels great. We will take it out later and do a little torture testing on it. In the meantime we are working on the kamikaze cylinder for his stock 250r. It will either finish the race or blow it's self up trying.:naughty: When that is done we are going to take it out with the 300 and see what we have.:naughty:

Daddio
06-09-2008, 10:01 PM
Well got the clutch working very smoothly, finally. It will go to trikefest virtually untested under racing conditions though. I'll give a report on it's durability after trikefest. See you there. :Bounce :beer :Bounce Here is a picture of it installed.
http://i39.photobucket.com/albums/e183/lrdunlap/100_0415.jpg

tecat-z
06-09-2008, 11:34 PM
Wow!!! Quick change cover. Did you have that made? Looks very nice and can't wait to see it in action.:beer

Daddio
06-19-2008, 09:24 PM
Wow!!! Quick change cover. Did you have that made? Looks very nice and can't wait to see it in action.:beer

No that is stock. By now you can say that you've seen it in action. :naughty:

The clutch itself worked like a dream. It hooked up very well, and operated very smoothly. The only problem that he had with it is the broken clutch cable. The clutch cable on it broke last summer and it ended the racing for the day. When we got home he ordered two new Honda cables and always carries a spare now. I think it's the heavy duty springs he runs in it that causes the cables to break so often. He ordered two more cables Monday night.

Daddio
08-14-2008, 10:55 PM
Okay I have an update on the 300. I guess when you do something that hasn't been tried before you can expect to run into a few problems.
The clutch performed well at TF but needed frequent adjustment. During the races at dirt country it did well but continued to need frequent adjustment. It was washed and put away after the race. When it was time to do race prep for the next race 1upfront noticed that he was running out of adjustment so he pulled the clutch to see if everything was intact. The first thing that he noticed was that the clutch rod wouldn't slide out of the engine. Not a good sign. So instead of running the risk of destroying something we pulled the engine again. He had to split the cases in order to get the rod out. The end of the rod that I had welded on to lengthen had failed. The steel from the weld wasn't as hard as the rod and it mushroomed out. this is why it needed constant adjustmentand also why it wouldn't slide out of the shaft. The next thing was the brass didn't hold on the clutch hub up either. That didn't make me feel very good. At least we made it to TF with it and made a good showing. Also nothing else in the engine was ruined. I guess nothing ventured nothing gained.
Well while the engine was apart a few questionable bearings were replaced and it is all back together except for the clutch. We took a good clutch rod to a machine shop and and they are going to custom make some that are 3mm longer than stock. We also took a clutch gear and hub to have welded. We asked the guy how much it would cost to make a one piece hub and he said that it would be about $1500 for the first one. That was all we needed to hear. He also said that he could make billet clutch baskets but they wouldn't be cheap either. So hopefully after this the clutch won't be an issue any more.
Here are a few pics of the old clutch rod.
http://i39.photobucket.com/albums/e183/lrdunlap/100_0540.jpg

http://i39.photobucket.com/albums/e183/lrdunlap/100_0539.jpg

88 Turbo Coupe
12-02-2008, 06:10 AM
[QUOTE=Daddio;626495]On the second race of the year 1upfronts 300r smoked the clutch in a bad way. He said that he wouldn't put it back together until he could find something more durable than the stock set-up. Well after much research we decided that no one makes anything for the air cooled Rs. So he said that he thought that the 78-80 cr 250 shared the same clutch as the 81-84 R. I looked into the prospect of finding out what was available for these. I was able to find a billet clutch basket for the cr 250 on ebay uk. It was quite pricey and took a while to get this guy to ship it to the states.
The next problem was the play where the kick start gear fits into the clutch drive gear. This is important because the clutch bearings fit inside of the kick start gear and the gear actually supports the drive gear and basket. We thought that welding the two together would solve this problem. The drive gear is cast so that limits what you can do as far as welding. So after much discussion with many people we decided to braze the two together. That went pretty well. After brazing we put it in the oven and let it cool down over a period of several hours.
The next problem was that the center of the gear that rides on the bearing had shrunk about five thousandths of an inch and it no longer fit on the bearing. We took it over to a good friend of mine, who is the local Harley guru and millwright, and he honed it back to stock specs.
Now we are ready to join the new basket to the modified drive gear. The new basket came with solid rivet for this task. This would be easy with a rivet press but I don't have one so we had to do it the hard way. The old hammer and bucking bar method.
This new basket uses 300ex clutch plates and the stock hub and steel plates. He bought some cr500 clutch springs for it and as soon as the new steels get here it will be going back together for a trial run then weather permitting we will be taking it to Dirt Country on the 7th for a TF warm up.


I'm not clear what needed to be done to the rivets. Can you explain?

1upfront
01-16-2009, 12:10 AM
The factory rivets have to be drilled off and when you get the new basket on you have to buck the new rivets, basicly strike them with a hammer and punch with something solid underneath on the backside of the rivet and they will spread out and become tight.