~ Engine Bearings Explained ~
As noted by Marcel van der Heijde <mheijd@xs4all.nl> on
The BevelHeads List 12/12/02 - Use this info as you please but...
Don't get mad at anyone if things don't work out as you planned

Hi heads,

Since somebody wanted to post my comments regarding bearings on a website I did some additional homework.

When I had my 860 GTS engine open ('76 # 852554) I went through the bearings as well. As it was opened by somebody else a couple of years before I got it, I had to in fact replace all bearings. This is the list I came up with at that time with the help of a local bearing supplier who still had access to old RIV codes. In fact RIV was bought by SKF. I took the part numbers from an 860GT parts manual because that is the only one I have (so not the GTS version), but for most bearings these will be the same as used on my engine and later SS or Darmah engines.

So here is my list. If you want to put it on a website feel free to do so, as long as you include some sort of disclaimer that anybody is still responsible for his own actions or something like that. (Use it, abuse it, but don't blame me!)

The notes on the suffixes were taken from the catalogues of bearing suppliers, as was the limiting temperature for the reinforced PA cages. FAG and SKF use identical temperature limits by the way.

Cheers, 
Marcel van der Heijde <mheijd@xs4all.nl


SKF suffixes used:

Angular contact ball bearings (72xx / 73xx)

  • A with 30 contact angle
  • B with 40 contact angle (BE preferred)
  • BE with 40 contact angle and optimised internal design
  • CB for paired mounting in random order with normal clearance
  • M machined brass cage
  • P with glass fibre reinforced polyamide 6.6 cage (max. 120 C)

Deep grove ball bearings (6xxx)

  • N with snap ring groove in outer ring
  • NR with snap ring groove and snap ring installed in outer ring (it is possible to use an N type and re-use the snap ring from the old bearing)
  • C3 1 step larger internal clearance than 'normal'
  • RS1 Synthetic rubber seal (NBR rubbing seal) with sheet steel reinforcement at one side of bearing
  • 2RS1 RS1 seals on both sides, grease filled
  • Z Pressed steel seal on one side of bearing (possible to buy double seal type 2Z and remove one seal)

Dual row self aligning ball bearings (12xx)

  • ETN9 Optimised internal design with glass fibre reinforced polyamide 6.6 cage (max. 120 C)
  • V with glass fibre reinforced polyamide 6.6 cage (max. 120 C) (FAG T suffix)

Roller bearings (NUxxx)

  • EC Optimised internal design incorporating more and/or larger rollers and with modified roller/end flange contact

In general bearings with a sheet metal, pressed steel or brass cage are preferred for applications where continuous use over 100 C is expected. Ducati advised metal cages only for the bevels as far as I know, but for the lower end of the engine the use of glass fibre reinforced polyamide cages shouldn't be too much of a problem (up to 120 C). The bearings on the  tower shaft and on the camshaft should have metal cages if you can get your hands on them. In fact the bearings in the lower end are easier to get with metal cages. Ask the bearing supplier if he can supply specials with metal cages.

They might not be included in the standard bearing catalogue on all occasions but they might be available if he is willing to ask the manufacturer.

There also is some discussion on the main crankshaft bearings. As far as I know ordinary B-types were used, but since I don't have the originals to check (previous overhaul before) I cannot be sure. The old RIV code was checked by an SKF representative and they told me it was a 7307 BE or equivalent.

The only bearings where Ducati uses C3 tolerance are the camshaft bearings so one could use normal clearance on all other bearings. 

I prefer to use C3 tolerance deep groove ball bearings in my engine and I used a 6008-RS1 on the output shaft, making it oil lubricated instead of the grease filled 6008-2RS1. If you use the 2RS1 keep an eye on the application temperatures for the grease used.

The only bearings where Ducati uses C3 tolerance are the camshaft bearings so one could use normal clearance on all other bearings as well.

Clutch housing up to engine no 851193

  • 75162.2566 RIV 6005-2RS = 6005-2RS1

from engine no 851194

  • 75113.2566 RIV 6005 = 6005

The GTS uses a modified clutch housing with one 6005 NR and one 7205 BE bearing.

Tower shafts

Top bearing

  • 75243.1747 U117-1203 Hoffman = 1203
  • SKF has a 1203ETN9 (max 120 C)
  • FAG has a 1203TV (max 120 C)

For this application it is probably worth searching for the metal cage types, but they should be considered specials and will be hard to find.

Lower bearings

  • 75380.1747 RIV 4A = 7203A
  • SKF has 7203 types with BEP / BECBP or BECBM
  • FAG has 7203 B.TVP

The B-types have a contact angle of 40 instead of 30 for the A type.

  • Preferred type from above 7203 BECBM

Right hand side engine casing

Layshaft bearing

  • 75120.2054 RIV 1A20 = 6204

Output shaft bearing

  • 75162.3683 RIV 10L40 = 6008 2RS1
  • a 6008 RS1 could be used if you prefer oil instead if grease for lubrication

Main crankshaft bearing

  • 75143.3380 RIV 630107 = 7307 BE
  • SKF has 7307 types with BEP / BECBP / BECBM / BECBY
  • FAG has 7307B.TVP
  • Preferred type from above 7307 BECBM

Left hand side engine casing

Main crankshaft bearing

  • 75143.3380 RIV 630107 = 7307 BE
  • SKF has 7307 types with BEP / BECBP / BECBM / BECBY
  • FAG has 7307B.TVP
  • Preferred type from above 7307 BECBM

Output shaft bearing

  • 75120.3075 RIV 3A30 = 6206

Layshaft bearing

  • 75120.2054 RIV 1A20 = 6204

Bearing on end of crankshaft

  • 75155.2054 RIV 1APL20 = 6204-Z

Bevel shaft support on RH side

Bearings for horizontal bevel shafts

  • 75195.1542 RIV 6302 NR = 6302 NR

Bearing for crankshaft

  • 75790.2054 RIV NU204 = NU 204 EC

Cylinder heads

Camshaft bearings

  • 75120.1542 RIV02A C3 = 6202 C3

Use metal cages on these bearings and ask for C3 clearance.


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