Finding M25 shoulder bearings seems really difficult to say the least. Any advice out there for a source of Steyr or FAG bearings with brass cage? I found:
1) FAG M25-TVP with polyamid cage (from a German supplier). These are rated to only 90 C. One would worry about the temperature stability and resistance against gasoline and oil. Do people have experience with those?
2) M25 bearings of undisclosed make (probably from a Chinese manufacturer) apparently with brass cage (from a British supplier). Is there any experience out there using Chinese bearings?
I understand that at least one of the Chinese manufacturer stoped making those too. Availability of crank bearings may become an important issue for fixing engines.
I would greatly appreciate to hear about your experience before spending money on this!
Thanks
Andreas
P.S.: Yes I did check with Al Buehner.
Most of us here have been using one piece bearings. Makes it harder to shim cases, but can be done.
I wouldn't worry about polyamid cage. Those were used in new KTM's as early as 1981 and probably before. I replaced mains (M30)in my 1981 495 and the originals had the polyamid cage as did the new bearings.
Tony
I have some that I had made for me. They are slim here in the states. Email me at
[email protected]
Andreas, I have gotten bearings for these motors and trans from Bartlett Bearing in Birmingham 866 987-1915. They got me Consolidated M20 and M25 separable race types, as well as some of the odd needle bearings in the trans shafts. I work with Bartlett daily in my electric motor repair business. Tell em I sent ya.
Keith Meatyard
Thanks Keith! I've contacted them with reference to you.
Andreas
Just use modern one piece bearings. Modern Sea Doo watercraft main bearings (Rotax engines) have polyamid cages.
Whatever you do, DO NOT use Chinese bearings on the crank. Wheel bearings and other places are fine for Chinese bearings, but main bearings are a bad idea.
Brian
The problem with the Chinese bearings is that the balls are smaller and the internal race is fatter. When to try to put the case halves together, the balls get pushed out of the groove in the internal race (small balls & small groove). This results in a lot of grief and aggravation.
I wound up with a shipment of these last year and wound up sending them all back. A costly lesson for me with double freight charges and import tariff fees. :( STAY AWAY FROM THESE BEARINGS - specify the FAG brand when searching.
Alan Buehner
If using the one pc bearing is the process for shimming the crank the same as using the M20,s ???.. thks BT
Brian Taylor
Got two of the good German made FAG M25 bearings with brass cage:
http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3342_zps2a4718bb.jpg.html?sort=3&o=1
Here my collection of new FAG bearings for engine and transmission rebuild:
http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3345_zps58d79312.jpg.html?sort=3&o=0
Thanks for the guidance!
Andreas
Hi All,
I am fixing to install the new bearings now. Have a look at the picture below:
http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3531_zpsb3228b19.jpg.html?sort=3&o=0
This is how I found the crank seals installed when dismantling the engine. On the left (clutch) side seal carrier the seal spring points to the outside. On the right (mag) side seal carrier the seal spring points to the inside. Isn't the right side wrong and needs to be assembled the other way around? This sure needs to be uniform.
Thanks in advance!
Andreas
Check out this thread on crank seal orientation, it seems that the spring always go on the inside toward the crank. Mike
http://pentonusa.org/forum/topic.asp?TOPIC_ID=12246&SearchTerms=crank,seal,placement
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
1975 Can Am 175 TNT & 77 250 Black Widow
1979 Husqvarna OR390
1976-78 RM & 77-79 PE Suzuki's
1974 CR250M 07 CR125R 79 CR250R
Thanks, this makes sense.
Andreas
Just looked in the Penton repair manual. Spring (therefore the lip) faces the crank, both seals.
Keith Meatyard
I've installed, after pre-heating the case, the crankshaft main bearings and the transmission bearings, all FAG brand:
http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3538_zps446b7777.jpg.html?sort=3&o=1
http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3541_zps215561fe.jpg.html?sort=3&o=0
In the process I've encountered another problem on the transmission side: while the small FAG 6203.C3 fit well, the larger FAG 6205 don't! The larger bearings are both loose. Is there any way to secure those? Are the FAG bearings known to have a loose fit? Needless to say: I don't really want to get a new crank case.
Thanks
Andreas
All bearings of the same size but different manufacturer will be the same size dimensionally, they all meet the same tolerances. If the bearings are loose (not interference when the case has cooled down), then the bore in the case is worn and will affect reliability. In the ball bearing world, one of the fits, either the outer race or the inner race is a slip fit while the other is an interference fit. In the case of these motorcycles, the shafts have the slip fit in the inner race to allow assembly. The outer race can be inserted into the case bore when the case is heated because of the greater thermal expansion coefficient of the magnesium verses the steel race.
Keith Meatyard
Any experience with products like Loctite 640 retaining compound? These are advertised to address problems like this.
Andreas
Andreas,
It appears from your photos you have a decent set of cases. So how loose are the bearings in the cases? Were the old bearings bad, did they spin in the bore and hog it out? Is there alot of clearance, or only a few thousandths? You may be able to loctite them in and be fine. Loctite 271 high strength (red) should work if it's not too big a gap. I have not used Loctite 640 but in my experience their products work as advertised.
This is of course your call as a mechanic.
I have used SKF ball bearings from a local industrial supply, they are good bearings but as Kieth said would not vary in size from FAG or any other brand.
The original bearings were loose too. The engine was not in running condition when I got it so I only know what I can see now.
There is a slip fit between case and outer bearing race, the bearings will simply fall out when the case is turned over. I don't want to operate the engine like this because this can only become worse if they start spinning in the case. The gap is indeed very small, I can't even get the 0.1 mm feeler gauge in between case and bearing. I Loctite is probably the way to go. The thing that worries me: will I be able to get these bearings out if I ever need to? That's why I am asking whether there is some experience out there on how to fix this problem. This sure must be a common issue with old engines.
Thanks for your input!
Andreas
My experience with materials like Loctite is that it can be heated with a torch to a point it will release when needed. Carefully heat the bosses to a point where things start smoking and the Loctite will crystallize and release the part. On machine parts with a loose bearing fit, I sometimes lightly dimple the seating surfaces with a center punch. This raises some metal and gives something for the outer race to push against, and also use Loctite to secure the bearing. Do a thorough job on the rebuild and unless you really thrash the engine by racing it hard, you may never have to worry about getting back in there again.
Good luck and have fun,
Dan McEntee
I used the center punch method to secure the transmission bearings:
http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3550_zpsd963d5cc.jpg.html?sort=3&o=1
http://s1341.photobucket.com/user/andreas_g_piepke/media/Penton/100_3551_zps5ef1da3f.jpg.html?sort=3&o=0
The bearings are tightly seated now. Let's hope they stay that way once the case warms up.
Thanks again for the input!
Andreas
6/13/2018
Hi, guys, rebuilding my 74 1/2 250 and I called Barlett in AL. They found plenty of these bearings at a supplier of theirs called Consolidated Bearings. The brand they are sending are FAG and have a plastic cage. Just an update FYI in case anyone is looking for these bearings.
Rgds
Where are the bearings made?
Quotequote:Originally posted by pastmxa
6/13/2018
Hi, guys, rebuilding my 74 1/2 250 and I called Barlett in AL. They found plenty of these bearings at a supplier of theirs called Consolidated Bearings. The brand they are sending are FAG and have a plastic cage. Just an update FYI in case anyone is looking for these bearings.
Rgds,
Richard
1976 MC 5 Original Owner
1976 Penton 175 XC
received the bearings, they look ok, FAG brand
I am avoiding bearings with plastic cage in two stroke engines. I am worried that the contact with the gasoline weakens the plastic over time. For the rebuild I did I got FAG bearings with brass cage.
Cheers
Andreas
'73 Penton Hare Scrambler
'73 Norton Commando
'77 Maico 440 GS
I didn't read all the postings, but one could switch to a two piece roller bearing on the mag side and use a standard ball bearing on the drive side, engine would still come apart easily and you wouldn't have to mess with shims!! Send checks to....lol!
smart....
Quotequote:Originally posted by JP Morgen
I didn't read all the postings, but one could switch to a two piece roller bearing on the mag side and use a standard ball bearing on the drive side, engine would still come apart easily and you wouldn't have to mess with shims!! Send checks to....lol!
1976 MC 5 Original Owner
1976 Penton 175 XC
You have this combination of roller and ball bearings in Maico engines. This allows for the different thermal expansion of the engine case and crank shaft without the need for shimming. I just rebuilt a 1977 Maico. However, these roller bearings are hard to find and pricey too.
Andreas
'73 Penton Hare Scrambler
'73 Norton Commando
'77 Maico 440 GS
https://www.ebay.com/itm/SNR-30305-25-X-62-X-17-TAPER-ROLLER-BEARING-30305-SNR-30-305/113149662474?hash=item1a583ed50a%3Ag%3AEBYAAOSwQJxa0lj7&_sacat=0&_nkw=25+x+62+roller+bearing&_from=R40&rt=nc&_trksid=m570.l1313