Counter balance Bearings

[bretb81]

I had just stripped a GS500 engine to find the RHS C/B bearing shot. Previous threads have shown this to be a common problem. Has all the failures been the RHS. The manual is incorrect in the specificaion for this bearing and most of the bearings and spacers are discontinued. Has anyone had success in repairing this. The crankcase area around the bearing is badly marked, I plan to use Locktite bearing lock to take up the slack. I have successfully used this for stub axle repairs after bearing failures. 

[dgyver]

Ronayers.com has the bearings listed as curent part numbers. Where did you see them as discontinued?

[sledge]

Cant comment on the bearings but like DG says I cant see them being discontinued, the bike is still a current model and all parts should be available from Suzuki dealers

What is it that makes you think the manual is incorrect regarding the bearing spec`, please elaborate?

Also bear in mind Loctite is essentially a glue and not a filler, I have been  led to believe its ok for gaps up to aroundabout 0.010" anything above that and you are taking a chance. However 0.010" is probably more than the allowed tollerances between bearing housings on the LH and RH casings. In other words if one side is worn, you will struggle to get it perfectly in line with the other regardless of how you try to repair ir.

[bretb81]

If you check the current Suzuki parts manual, there are three spacers listed (originally different parts with different tolerances) these now all have the same part number. The manual describes an etched letter (A or B) stamped on the C/B which gives the outer tolerances of the bearing journals. This is fine for the LHS, but the RHS has the spacer (it has no etched letter where the manual states) and a letter would be irrelevant. The dimensions of the spacers is not available, I have contacted Suzuki are they have no idea. Since the bearing shell and spacer are RS on my motor I am unable to measure their dimensions. I have guessed the required parts are will work backwards after measuring tolerances. I have a feeling the bottom end in this motor is common with the old GS250, which given the increased C/B weight would account for the bearing failures. 

[sledge]

The bearing shells come in 4 sizes and are colour coded. They are identified by a spot of colour on the side, green, black, brown or yellow. You may be lucky and see some colour left. The correct size of bearing is arrived at by cross referencing the relevent crankcase ID with the shaft OD. The crankcase ID can be one of 2 sizes, A or B. This is indicated by a group of letter stamps on the rear surface of the upper crankcase, not the shaft itself. Top row, far left and far right indicate the C/B I/D sizes. (Note LH and RH are not neccesarily going to be the same). The bottom stamps indicate the crankshaft bearing sizes but thats another story. The stamps can be seen on the case directly in front of the back wheel with the engine still in the frame.

Crankcase I/D sizes.

A=35.000-35.008
B= 35.008-35.016

These figures are confusing as a size of 35.008 could be either A or B and anything larger than 35.016 means the cases are toast. If you are on .008 I woud go with A

The C/B journal size can be in one of 3 groups and is arrived at by measuring the O/D with an accurate Micrometer and placing it one of 3 tolerance brackets, it will be classed as A B or C dependent on its size. there is no letter stamped anywhere on it to indicate its size as it is wears in use unlike the crankcase I/D which in theory shouldnt.

A= 31.992-32-000
B= 31.984-31.992
C= 31.976-31.984

Again these figures are confusing owing to the changeover points i.e a size of 31.984 could be B or C. Anything less than 31.976 and the shaft is toast.


Then cross reference the ID with the OD on the Suzuki identification table quoted in the manual to arrive at the correct bearing size.

Crankcase A with shaft journal A is green, with B is black with c is brown
Crankcase B with shaft journal A is black, with B is brown with c is yellow.

Part Nos.
green  12229-01D00-0A0
black   12229-01D00-0B0
brown  12229-01D00-0C0
yellow  12229-01D00-0D0

All this info I have lifted directly from the GS5 Suzuki service manual, I find it far better than Haynes or Clymers when it comes to issues like this. It is covered in section 3.36-3.37. I dont have a scanner or I would be happy to mail you a copy, perhaps someone else will be kind enough to offer to do it for you. C/B bearing failure is not unheard of in this forum but it is rare, most cases are down to poor lubrication, ie lack of oil changes and blocked oil galleries. The engine is generally regarded as bulletproof and I personally am not aware of any comparisons with the GS2.5 bottom end. If you have metal missing from the crankcase area surrounding the shells you will have alignment/support problems between the RH and LH cases and the bearing life will be reduced. My manual makes no mention of any spacers on the C/B shaft that require replacement, are you talking about crankshaft thrust washers? Or maybe it is a latter mod or someone has already been in there and tried to effect a repair/mod.
I  have never changed the bearings in a GS5 but have done in other similar bikes, the bearing selction/identification methods used are similar for most makes and models. However there are guys in here like DG and Ken who have changed bearings and may want to add their own comments.
   

[bretb81]

The problem is the spacer on the C/B RHS. There are three listed in the parts book, however two are discontinued. There is no mention of the differences between them, I assume they are different dimensions which match the three alternate bearing shells. I have guessed the part number sequence is in-line with the different bearings and have ordered the parts accordingly. I'll check the tolerances and then may have to order other shells to match. A bit hit and miss but it is the only alternative. The bearing journals are identical to those on the earlier GS250/GSX250 engine, which may explain why this is a weakness in the GS500 engine. Crankshaft bearing are also identical and all shared with the ealier capacity increase in the GS425/GS450 (same bottom end). The greater weight of the C/B for the increased capacity overstresses the bearings. I don't think there has been the same failure rate with the smaller engine.

[Gisser]

The bearing journals are identical to those on the earlier GS250/GSX250 engine, which may explain why this is a weakness in the GS500 engine. Crankshaft bearing are also identical and all shared with the ealier capacity increase in the GS425/GS450 (same bottom end).

The GS450 is the 1st gen plain brg Suzuki twin.  The 425 belongs to the GS400 engine family and uses ball brgs on the C/B.  The GS250 came a year or two later and apparently borrows GS450 brgs for the sake of standardization (good ol' parts bin engineering).  Your spacers sound like thrust washers--which would control end-play and would be unrelated to plain brg size.  Not too important as long as you have minimum clearance.  At any rate, Loctite is a bandaid not a miracle.  Take that into consideration before you sink any more time & money into this project.