Clutch Basket Bearing Recommendations? 860GT

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Old905Duc
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Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Sat Jan 02, 2016 5:43 pm

I am in the process of upgrading the clutch on my early (1975) 860 GT. I have purchased a NOS clutch basket (Ducati P/N 0759.16.814). This clutch basket requires two unique bearings instead of the two common bearings used in the earlier original design. Based on Ducati parts manuals the bearing sizes are:
1) 25x47x12 with a snap ring in the outer bearing housing, and
2) 25x52x15 (no snap ring)
I have found two online sources for these bearing configurations, but I am uncertain on a few points that I hope the forum can clarify before I order bearings............
A) Is it better to use open bearings, or bearings with seals?
B) Should standard or C3 clearances be used?
(For reference my original early clutch basket used sealed bearings with "C3" marked on the seals)

Next, I am wondering if these bearings can be easily tapped into place or if a press is required? What is your experience?

Finally, I am open to any recommendations related to online sources for these bearings.

Thanks in advance for your valued advice on these questions.

jockduck
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Re: Clutch Basket Bearing Recommendations? 860GT

Post by jockduck » Mon Jan 04, 2016 2:30 pm

Just to show being ignorant does not prevent one from voicing an opinion, Always a little puzzled at Ducati's constant fiddling with 860/900 clutches, I would use C3 like the old ones, the fit in the drum will be tight hence the need for clearance. A press is good if available but a suitable hammer and drift with care will also work. The important thing is the preload between the bearings there should be some shimming involved(it IS a Ducati)
Why the reason for the upgrade?
Jock

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Mon Jan 04, 2016 4:57 pm

Hello Jockduc,
Thanks for your response. Why upgrade the clutch? Well here goes .........

I am the original owner of this bike. I've had it for 39 years. After 50k miles the clutch has now started to slip (not too unreasonable). My first instinct was to replace friction disks and springs and be done with it. However, because my 860 is a very early version it has the early original clutch design version. As it turns out no one sells friction plates for the early clutch design. The later clutch design is thicker overall with thicker friction plates to reduce wear and grooves on the inner hub splines. The thicker later design means a new basket, new hub, new friction plates, and by the way also new differnet basket bearings :-).

So, I decided to upgarde to the later clutch design because the friction plates are still supported (and to move to the more robust design).

Thanks for your thoughts on the bearing clearances and installation .. press vs. hammer/drift. I agree with your rationale on the C3 clearance.

Now your comment on the bearing preload "shimming" has got me thinking. I have attached a diagram for the clutch version that I am installing. You can click on it for a bigger image. Items 55 and 38 (washer / shim) are common for all design versions (I believe) and I will use them. The first basket bearing (item 17) locates against a shoulder in the basket bore. The second basket bearing (item 16 with snap ring) locates against the first bearing when it is pressed into place (inner race to inner race) with no spacer. This is my understanding(?). Your comment makes me wonder if any other "preload" shimming is involved or expected. Can you comment further on this? Is any additional "shimming" expected from your perspective?

Finally, although I have owned this bike for a long time I am no expert. So, I do appreciate your thoughts and comments.

Take care.
Old905Duc
Clutch and Transmission Diagram - Later Design.jpg
Last edited by Old905Duc on Sat Mar 05, 2016 4:00 pm, edited 1 time in total.

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by jockduck » Thu Jan 07, 2016 3:47 am

You are gonna hate this, I too have an early 860GT with the skinny clutch, the bike has done a lot of miles(90000+) and the clutch was very worn, I did manage to buy a good centre (I suspect you could turn a GTS one down if you wanted) as you might expect the splines on the friction plates were VERY worn, most less than half left. and yes the later and earlier plates are too thick, I bought a set of new skinny plates from Gowanlochs in NSW in Australia, they are/were being sold as a pack of 10 plates so that people could fix slipping clutches in GTS,900SS, MHRs etc using 10 friction plates instead of the standard 8, the kits are made supplied by Sureflex I think part No S1197/B. So my clutch is happy, no slipping just tends to grab a little at take off, probably needs the shimming fixed!
You are right the later clutch does not appear to have any shimming but the early one does, I know the arrangements are different but without having one in my hands I'm not sure I guess the two bearings are just sandwiched together with no preload.
I forgot to mention a reply to you query about sealed of unsealed bearings, weird thing I think the original clutch bearings were sealed, possibly they were cheaper when bought in bulk by Ducati. The snap ringed bearing in my GTS is of the open type and I think it is original, I think either type will do. There is not much oil in the clutch centre area but with time sealed bearings need re-lubing but by then the seals are leaking so some oil gets in.
Jock

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Thu Jan 07, 2016 12:06 pm

Hmm ...... thanks for the interesting information. I was not aware that new "skinny" friction plates were available from any source. I just now glanced quickly at the Gowanlochs online store and did not find them, but maybe an individual query is required to dig them out. As it turns out Steve does have a lightly used early 860 center hub in his parts store. So, This would be an easier option. However, I have already purchased all of the conversion parts except the bearings. BTW, do you recall the cost of the "skinny" plates that you purchased? Maybe this is still an option if they are still available and if I can return the parts that I already purchased(?).

Thanks also for your additional comments on the bearing preload and seal considerations. You have me thinking now if I should change my path.

BTW, since your early GT also has a lot of miles I am wondering if you ever rebuilt the bottom end? Mine is orginal (50k miles) but I see a few opinions that this is way overdue :-). Anyway, I am not about to tear into it at this point.

Take care.
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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Thu Jan 07, 2016 5:29 pm

I sent an email inquiry to Gowanlochs about the clutch kit that you mentioned. They responded that they do not sell that kit any longer. Instead they have a kevlar relining service that they run on a parts exchange basis ....... you provide your pressure plate and friction plates, and they exchange with a set already relined in kevlar. Apparently the kevlar gives much better holding power without the use of heavy springs. On an exchange basis the cost is about $305 AUD. Shipping is extra. I am now trying to confirm if they offer this service for the early "thinner" friction plates or only the more common later thicker versions. In the mean time I am about out of runway for the return of the parts that I have already purchased.

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Vince » Fri Jan 08, 2016 1:06 am

I have these relinned plates in my Laverda, they work extremely well.Zero slip and heaps of fun off the traffic lights. I expect there done by the same place in OZ as I am in Sydney. Make sure you clean any mesh oil strainer after a 1000k or so as they do shed a bit at first.

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by jockduck » Fri Jan 08, 2016 3:32 am

Stop! Sorry I made a mistake, I got the clutch plates from Italspares, Ian Gowanlochs business, Pt No S1197B, I bought them 25-Jan-2013 Ian does not run a website only email, iangowanloch@bigpond.com may not answer straight away. cost $144 Au.
I bought my GT in 1985 as a basket case and rebuilt it, first ran in 1987 been running ever since. When I bought it the crank had just been rebuilt by Brook Henry, there was a pair of new cylinder liners so I had them bored to suit the original 86mm pistons, everything else was shimmed up and put back in, I have done 146000km since then and only both heads have been off once, the rear at 30000 to have the plug hole helicoiled and the front at 65000 for a new exhaust valve and guide, and apart from the clutch plates and ignition stator nothing else has been changed, The bike must have done a fair mileage before I bought it to blow the crank, the clutch was in pretty used condition in 1987. Duck owners get a bit obsessed about cranks and oil, I think Ducatis heat treatment in the seventies was a bit all over the place, some original cranks have done over 100k miles a lot have not, pulling an engine down and splitting a crank for no reason is not fun, I know I wasted weeks doing that on my GTS.
Not very convinced about having bits of Kevlar swimming about in my engine oil,
I am a "leave well alone" guy and need a good reason to dive into an engine, I guess one day I'll get a surprise and the bike will lose its lunch.
Jock

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Fri Jan 08, 2016 10:56 am

Thanks Vince for your experience with kevlar clutch plates with your Laverda. I always liked Laverda's ...... especially after I heard my first tripple many years ago!

Jock,
Thanks for your update on the "thin" Surflex kit and the source reference. BTW, I did close with a rep from the Gowanlochs web site and they can provide the kevlar upgrade to the thinner plates although it is a little out of the ordinary compared to the more common thicker plates. Anyway, I am already too far down the road (with parts already purchased) to change my direction at this time..... can't roll back the clock.

Interesting to hear the story of your 860GT. I am the original owner of mine; now has 50K miles. Engine-wise I have replaced the ignition 2x times and am now using the old Lucas Rita conversion. I installed Bracken 88mm 10:1 pistons at about 42K and at the same time had the heads freshened with new guides, rocker shafts and bushings, and a valve job. At 48k one of the spark plug hole stripped out and I decided to pull both heads and install inserts in each. I have not touched the bottom end. Since I am not riding so much anymore I have no plans to tear into it proactively. Like they say; if it is not broken ..... Anyway, hopefully we both can enjoy many more miles before the bottom end lets go :-).

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Mon Jan 11, 2016 9:13 pm

Hello All,
Just an update with respect to my original question on clutch basket bearings......

I have decided to go with sealed bearings with C3 clearances ....... C3 to accomodate the press fit, and sealed because my original bearings were sealed and they seem just fine after 50K miles. My original intent was to use SKF bearings, but I could not find an online source for SKF with the sealed/C3/Snap Ring configuration. So, instead I went with Nachi; a good quality Japanese manufacturer I understand. The Nachi part numbers are:
6005-2NSENR - 25x47x12 Deep Groove Ball Bearing, C3 clearance, Sealed, with Snap Ring.
6205-2NSE - 25x52x15 Deep Groove Ball Bearing, C3 clearance, Sealed.
I was able to order these online at VXB Online Bearings for a pretty reasonable price.

The remainder of my clutch upgrade includes:
1) Later model clutch basket and hub
2) New friction plates
3) Heavy clutch springs
4) Longer "light pull" clutch lever kit

The last detail to work through (I think) is the clutch push rod / ball / spacer length. With the new deeper clutch basket I think some adjustment will be needed here. I'll figure that out when the other parts are installed.

Old905Duc
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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Sat Jan 16, 2016 10:20 pm

A few thoughts on clutch basket bearing installation .........

None of my manuals gave any information on bearing installation for the clutch basket .... its all intuative, no?. Anyway, I learned a few things in my first trial:

1) Heating the basket makes the installation quite easy. I used my wifes hair drier to get the basket as warm as possible.

2) Cooling the bearings also helps. I put the bearings in the refrigerator over night. I decided not to put them in the freezer just because I did not like the idea of freezing the grease, but this may not be a problem.

3) The larger 52mm OD bearing just needs to be driven to the shoulder in the basket bore. I used a big socket that matched the bearing outer race size. This way I was not tapping directly on the bearing race. The socket is held against the bearing and I tap on the socket with a hammer.

4) The smaller 47mm OD bearing takes a little more attention. Again I used a large socket matching the bearing outer race to drive it into position. In this case there is no shoulder to set the position. The bearing has a snap ring in the outer race, but this cannot be used to set the seated position. I mistakenly used the snap ring as a guide and this resulted in too much prelaod on the bearings (too tight). I ended up driving them back out and then ordered new bearings. Instead you need to drive them until the inner races just touch. As you get close you need to keep checking so that you do not drive too far and induce too much preload in the bearings.

Other than these points I cleaned the basket bearing bores well and lightly dressed them with motor oil. I then wiped off the oil with paper towels which left just an extremely slight residue. My thinking is that this is better than a totally dry interface when pressing the bearings in place.

At this point I am waiting for my new set of bearings because I do not want to re-use the set that I pushed out (due to high preload) since I likely damaged the bearings when I removed them ...... although they did not seem to be indented(?).

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Wed Jan 27, 2016 5:46 pm

Progress Update.........
I have received my second set of bearings and successfully installed them into the clutch basket with no issues. This time I was very careful to SLOWLY tap and check the position of the smaller snap ring bearing until it just touched the matching inner race of the larger opposed bearing. No binding this time and the bearings turn freely. As before I heated the basket with a hair drier and cooled the bearings in the refrigerator over night. I also used sockets that matched the OD of the bearings placed against the bearing OD races and tapped on the socket rather than directly on the bearing. They went in easily.

Installation of the basket and hub onto the transmission shaft was straight forward. Since the engine was still in the frame I did not use the clutch tool (I don't have one) while tightening the hub nut. Instead I put the tramsmission in high gear, locked the rear brake, and placed a study bar between the rear wheel spokes and the swing arm. This stopped all rotation and allowed me to easily apply the full tightening torque to the hub nut.

I soaked the new friction disks in engine oil for a few days (not sure if this is really necessary) and installed the new friction plates and cleaned up the old steel plates. At this point I now have the later version clutch basket/hub/clutch plates installed on my early 860 :rad: , but we are not quite done yet.

I had decided to also install new HEAVY clutch springs for a good grip. Since the clutch pull was already "manly" with the original springs I decided to also install the easy pull longer clutch lever that Steve sells. Installation of the longer lever was easy ..... but you will need a snap ring pliers of the correct size. Installation of the heavier springs caused me some problems. It seems that the heavy springs are also longer than the originals. I found it quite hard to compress the springs to the point of engaging the screw threads. At this point I referred to the parts manuals and determined that the shims used in the screw cups (for early 860's) were not used on the later clutch design. Removing the shims helped but I was still afraid of stripping the initial threads. So, after checking the thread depth I decided to buy new (slightly) longer screws. The original screws are M5x12. The perfect size (I think) would be M5x14. I could not find that size but I ordered M5x16 which I will either cut down or use washers to reduce the effective length. The screws are now on order. Since I was buying new screws I also decided to change the head type to a flanged hex bolt head from the original slotted head. This will make it easier to compress the spring and eliminate the fragile screw driver slot. At this point I am waiting for the clutch screws to be delivered.......... could not find them locally.

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Fri Feb 05, 2016 6:40 pm

OK .... here is an update. In my last post I stated that I had ordered longer hex head clutch spring screws for easier installation of the heavy (and longer) clutch springs. The screws arrived and after considering my options I decided to order a bottom tap and slightly deepen the clutch spring threads to match the new longer (16mm) screws. With that modification I could easily install the stronger and longer (heavy) clutch springs. But all has not quite worked out well yet...........

It seems that these springs are also slightly bigger in diameter and (as expected) stronger. Well, after installation I found that the pressure plate was deforming and not fully lifting when the clutch lever was pulled. A little further investigation determined that the OD edge of the spring was rubbing on the inner surface of some of the spring cups. This appears to be part of the problem. I also noticed that there were some rather sharp edges at the end of the springs. As a trial I reinstalled my old clutch springs and the pressure plate lifted as normal. At this point I plan to dress the springs to remove any sharp edges. Then I think I will perform some trials using 3 old springs and 3 heavy springs. If this trial is successful I will then try installing the 3 remaining (edge relieved) heavy springs to see if the pressure plate will hold up under the load.

I would appreciate any advice that the forum can share related to my observations.

Thanks and happy riding.

OLD905DUC

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Sat Feb 06, 2016 5:41 pm

Clutch Spring Trial Update........
in my last update I noted that the clutch pressure plate would not lift properly (seemed to be binding) after installing the Heavy clutch springs. Installing the original springs resulted in normal operation (lift) of the pressure plate.

I then spent some time carefully dressing the ends of the Heavy springs to remove any burrs or sharp edges since I noticed scratches on the insides of some of the spring cups. Then as an experiment I installed 3 heavy springs and 3 of the original springs. Again the pressure plate seemed to bind and did not lift properly. Installing all 6 original springs allowed the pressure plate to lift normally. I was a little surprised; but this seems to confirm that the problem is related to the Heavy springs. They are slightly (~0.35mm) bigger in diameter and my thinking is that they may be binding/rubbing against the side of the spring cup(?). The only other difference is the washer in the bottom of the spring cup that I use with the original springs, but remove when using the Heavy springs. I assume that its purpose is to add a little preload to the original weaker springs(?).

So, at this point I haven't found a way to get these Heavy springs to work in my application :*<: .

Anyone have any ideas?

OLD905DUC

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Re: Clutch Basket Bearing Recommendations? 860GT

Post by Old905Duc » Sat Mar 05, 2016 10:01 am

Clutch Spring Resolution .......
I tried one more experiment with the Heavy (26Kg) springs. I added three 1mm thick washers to the spring bosses of the center hub to reduce the overall spring compression on assembly. The motivation for this was measurements that I took suggesting that the springs were becoming coil bound. Even with these washers added the pressure plate seemed to bind and deform slightly and would not lift properly. I did not force it fearing that I might damage something. So, still no luck.

At this point I decided to order the 22Kg springs that Steve sells. These springs have a thicker wire diameter but the same spring OD and compressed height as my original springs. These springs did the trick, and the operation of the clutch and the lift of the pressure plate seem to be normal by visual observation. I can't explain why the heavy (26Kg) springs did not work in my application, but it must somehow be due to the unique combination of parts (basket, center hub, pressure plate, spring cups). Other than the slightly longer free and compressed height, the other observed difference is a larger spring OD (by approximately 0.35mm) of the heavy (26Kg) springs. Anyway, I now seem to have a combination that works using the intermediate (22Kg) springs.

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