Twin row caged ball bearing. Fitted to Model 30M/40M (Manx) SOHC engines in original C3 looser fit, from good quality SNR manufacturer. 

This is the twin row bearing fitted to the timing side of SOHC magnesium crankcase M30/M40 (i.e. pre-Featherbed) Manx models.  It is different to the aluminium crankcase International models timing side bearing (which is only a single row bearing) - making the M30/Manx models stronger in this important area (which may explain why pre-featherbed M30/Manx magnesium crankcases are often found with the drive side crankcase damaged but timing side ok).

Original bearings had steel/bronze cages, but have not been available in that form for many years.  Modern versions of this bearing are now supplied with a nylon cage.  This is the correct looser fit 'C3' bearing as fitted to original models - but bear in mind the cage is nylon when soldering the whitworth screws over the bearing retaining plate - particularly if using a blowtorch, do not get the heat too close to the cage!

Update October 2019: These are a slightly cheaper brand of this twin row bearing than the SKF brand (Item 0022).  We have a small quantity of these SNR brand bearings, with the same C3 fit.  I spoke to my bearing supplier (a very experienced long term commercial supplier of bearings) who confirmed that these are also a good quality supplier - despite not having the same brand reputation as RHP/NSK/SKF etc.  I only have a limited quantity of these bearings left - but as sometimes the SKF version go out of stock, these are an alternative if you are less concerned about brand - construction and finish look virtually identical to the SKF version

3 screw mainshaft bearing securing plate, to fit all Model 30 and Model 40 International (and CS1/CJ) engines. This pressed steel plate was used to retain the main bearings and ensure they did not 'walk' under heavy use.

Price is Each

The plate was secured by 3 screws (sold seperately), which were soldered to the plate after tightening, to ensure they do not come lose. This plate is copied from an original item.

Note: this plate fits all International crankcases after approximately 1932. before that time a shallower plate was used. If you are not sure - measure the lip of the main bearing housing ( see second photo), if it sits approx. 0.225" above the crankcase wall it is for this plate. If it measures approximately 0.175" above crankcase - then the very early securing plate is required (see Item no 0287). The late type crankcase is on the left in the 3rd photo

Hints for Securing The Screws On These Plates:

Original SOHC engines used slotted, unplated screws (which we supply - Item 0023 and 0024), so they could be soldered in place to stop them unscrewing when the engine was running.  It is important to ensure you use unplated screws, as the solder will not adhere to plated screws.   Once bearings are fitted, the plates can then be held in place and the screws tightened up with a flat bladed screwdriver.  Then, originally, these screws were soldered over - ensuring the solder flows easily  over the head and surrounding plate (without too much spillage).  To do this requires that both the corners of the plate and the heads of the screws are absolutely clean and free from oil.  I also tend to use a rotary  wire brush on both to remove any surface corrosion, just before soldering.  Originally I believe plumbers solder would have been used (not electrical solder), but a good quality solder and flux is required to get a good finish.  It is then a case of simplly getting enough heat onto the area surrounding the screw hole of the bearing retainer plate and the head of the screw, until the solder flows freely of its own accord - which can sometimes be quite difficult. 

I will not advise anyone how to do this - that is for each owner to decide for themselves, but many soldering irons cannot convey enough heat to get the solder flowing, so a number of people use small gas blowlamps, with well localised flames - but great care should be taken if doing it this method to avoid rags or anything close igniting.

A picture is also attached of an original engine with International type bearing retainer plate fitted, and screws soldered over

4 screw mainshaft bearing securing plate, to fit all Model 30M and Model 40M  (i.e. pre-Featherbed Manx type) magnesium engines. This pressed steel plate was used to retain the main bearings and ensure they did not 'walk' under heavy use. The plate was secured by 4 screws (sold seperately - see item 0024), which were soldered to the plate after tightening, to ensure they do not come lose. This plate is copied from an original item.

Price is Each

Note, if you are not sure what type of SOHC engine yours is - normally the only engine to use the four hole type main bearing covers were the competition magnesium crankcase engine bikes - originally referred to as 30M or 40m, or Manx Grand Prix Specification or later just Manx Norton.   These should fit all pre-Featherbed type magnesium crankcases (and might also fit some Featherbed type - email for dimensions if you need to check).  There was also a very early aluminium type racing engine crankcase (approx 1932-35, but without any web on the drive side in the shape of the Oilbath) - I believe they normally used the 3 screw fixing plate - but if are fortunate enough to own one of those engines and are unsure, email us for more information (sales@racingvincent.co.uk).

Hints for Securing The Screws On These Plates:

Original SOHC engines used slotted, unplated screws (which we supply - Item 0023 and 0024), so they could be soldered in place to stop them unscrewing when the engine was running.  It is important to ensure you use unplated screws, as the solder will not adhere to plated screws.   Once bearings are fitted, the plates can then be held in place and the screws tightened up with a flat bladed screwdriver.  Then, originally, these screws were soldered over - ensuring the solder flows easily  over the head and surrounding plate (without too much spillage).  To do this requires that both the corners of the plate and the heads of the screws are absolutely clean and free from oil.  I also tend to use a rotary  wire brush on both to remove any surface corrosion, just before soldering.  Originally I believe plumbers solder would have been used (not electrical solder), but a good quality solder and flux is required to get a good finish.  It is then a case of simplly getting enough heat onto the area surrounding the screw hole of the bearing retainer plate and the head of the screw, until the solder flows freely of its own accord - which can sometimes be quite difficult. 

I will not advise anyone how to do this - that is for each owner to decide for themselves, but many soldering irons cannot convey enough heat to get the solder flowing, so a number of people use small gas blowlamps, with well localised flames - but great care should be taken if doing it this method to avoid rags or anything close igniting.

A picture is also attached of an original engine with International type bearing retainer plate fitted, and screws soldered over

This is the shallower type of Model 30/40 main bearing plate that was fitted to very early Cammy engines - we believe prior to 1933 (although it is difficult to be exactly sure when the lip was made larger - so please ensure you check your engine . . . there may be a year or so each way before the new lip type was introduced).

Price is each

If you have an early engine and are not sure which type you need, then measure how far the bearing lip stands proud of the inner crankcase wall (as In photo 2) - if it sits approx. 0.225" above the crankcase wall then you need the later type (Item no 0285). If it measures approximately 0.175" above crankcase then you have the early type crankcase and you need this bearing cover. The early type crankcase is on the right on the 3rd photograph.

We also sell the later post 1932 Inter bearing cover . . . and although they look very similar, you can see that this earlier cover is noticeably shallower.  And of course - being early, and only fitted for a short period . . . they are extremely difficult to find, and orginals are often damaged and dont solder well.  We had this cover specially made for us, based on an original plate.

This is the countersunk screw used to retain securing plates for both main bearings in the crankcases and front camshaft bearings.

This listing is for a bag of 3 screws (we also sell a larger bag of 9 screws - Item 0024)

These screws are the correct coarse thread, length and most importantly - are unplated, which is very important - as the original design of these bearing plates was for the screws to be soldered to the bearing plate - to ensure they did not come loose and drop into the crankcase in use - causing severe damage.

The normal SOHC roadgoing models used a 3 plate bearing cover, as did the first camshaft bearing cover, while 30M/40M (pre Featherbed Manx) models used a 4 screw bearing plate.

It is extremely important that both the screws and the bearing plate are burnished clean before attempting to solder, and I have always found it easiest to use a good quality flux, and a small blowtorch - as a suprising amount of heat is required before solder will melt over the head of the screw.  Ideally - the solder should 'puddle' over the head of the screw and surrounding plate countersink - to ensure a good join.  You need to be very careful if using this method with some modern bearings - which have now switched from a bronze to nylon ball cage - the heat must be kept away from the bearing cage.

Final point - in practice it is extremely difficult to avoid some level of 'mess' when doing this job - and normally trying to cover the bearings with a cloth or tape is not practical because of the heat.  In preference - if fitting new bearings, I do not place any oil into the bearings after fitting - until after I have finished soldering the bearing plate.  After soldering, I very carefully capture and remove any traces of spattered solder or flux from the area . . . and if any solder has landed on the bearings I very carefully remove that, before final oiling of bearings.

This is the countersunk screw used to retain securing plates for both main bearings in the crankcases and front camshaft bearings.

This listing is for a bag of 9 screws (we also sell a smaller bag of 3 screws - Item 0023)

These screws are the correct coarse thread, length and most importantly - are unplated, which is very important - as the original design of these bearing plates was for the screws to be soldered to the bearing plate - to ensure they did not come loose and drop into the crankcase in use - causing severe damage.

The normal SOHC roadgoing models used a 3 plate bearing cover, as did the first camshaft bearing cover, while 30M/40M (pre Featherbed Manx) models used a 4 screw bearing plate.

It is extremely important that both the screws and the bearing plate are burnished clean before attempting to solder, and I have always found it easiest to use a good quality flux, and a small blowtorch - as a suprising amount of heat is required before solder will melt over the head of the screw.  Ideally - the solder should 'puddle' over the head of the screw and surrounding plate countersink - to ensure a good join.  You need to be very careful if using this method with some modern bearings - which have now switched from a bronze to nylon ball cage - the heat must be kept away from the bearing cage.

Final point - in practice it is extremely difficult to avoid some level of 'mess' when doing this job - and normally trying to cover the bearings with a cloth or tape is not practical because of the heat.  In preference - if fitting new bearings, I do not place any oil into the bearings after fitting - until after I have finished soldering the bearing plate.  After soldering, I very carefully capture and remove any traces of spattered solder or flux from the area . . . and if any solder has landed on the bearings I very carefully remove that, before final oiling of bearings.

- Single row ball bearing. Fitted to all SOHC engines, both International and early Manx. 

These are either high quality RHP or SKF bearings -dependent on availability at the time - but both these manufacturers supply bearings of the highest quality. 

Orginally fitment for this front cambox bearing would have been 'C3' looser fit bearings - but those are now unobtainable, and often were not r-fitted once changed anyway.  These are the 'standard' fit type, but this should not really make a great deal of difference on this bearing - just give it a little more time to run in after fitting.  It is far better to fit good quality RHP/SKF bearings - than an inferior quality non UK bearing.

Note:  It us not unusual when stripping both SOHC and DOHC Manx Norton engines (i.e. racing engines) to find a slot ground into the outer race of this bearing, approximately 1/16" deep.  Then when fitting the 3 screw plate over this bearing on assembly - a screwdriver used to punch an indent on the bearing plate that corresponds with this slot.  This is done to make sure there is no chance of the bearing spinning in the housing.  Although I cannot advocate this being good engineering practice . . . I know I do it on all my engines built for racing!- also on main bearings (if you do do it - make sure you cover bearing with cling film or similar first, so nothing gets in bearing).  

- Single row caged roller bearing. Fitted to Model 30/40 (International) SOHC engines. These are either RHP or Hoffman (Hoffman became RHP) - both best quality and in correct and very difficult to find C3 fit.

(C3 type are slightly looser tolerance bearings and were originally used in these racing engines. The C3 type are not essential for cambox's - but are definitely a rare luxury today, when even the standard RHP type have been unavailable for the last couple of years). Not cheap - but the proper thing and when they are gone they are gone!!

Note this bearing, fitted to International Nortons is bigger than the bearing fitted to SOHC magnesium cambox backplates. This bearing is 1.812" outer diameter - to fit SOHC aluminium cambox's, in case you are not sure which bearing you require. 

Cambox Bearing - Camshaft Back Roller Bearing : as fitted to the Model 30M/40M (Manx) cambox backplate - identifiable from the standard International type, in that the Manx backplate is in magnesium.

These are the correct RHP C3 bearings - now unobtainable and very difficult and expensive to obtain.  These are the genuine areticle and therefore not cheap - apologies for price, but hope you would agree, it is much better to pay the price for the proper thing, rather than cheap Chinese copy!