E: Engine Big end needle roller bearings

[Phil Hogg]

Hello everyone, this is my first post here. I am trying to source quality KZK needle roller bearings 40 x 48 x 20 being my preferred size for big end use. INA were my first port of call as I knew they did this size, it seems no longer alas. In fact my bearing supplier has come up with nothing. Has anyone here any words of wisdom on the subject. I am in the drawing phase of planning a long stroke crank for a Comet special.
Thanks Phil.

 

[davidd]

Phil,

Maughan & Sons can do that. Also, Terry Prince in Australia.

I thought the stock Comet was a long stroke??

David

 

[vibrac]

Phil,

Maughan & Sons can do that. Also, Terry Prince in Australia.

I thought the stock Comet was a long stroke??

David

Not if you come from Cleckheaton

 

[oexing]

Hi Phil,
the bigger sizes of KZK needle bearings , 35/42/20 and 40/48/20 mm have been out of stock at INA since 20 years or so. That is the time I got some of the last bearings from a SKF dealer at high prices. I came across the 35/42/20 types when I looked into the Netherlands ABSAF web pages, maybe they still use that type. No idea where they get these. INA might be willing to supply a decent number to certain companies on special order - possibly from a former supplier in China - as I found out and got a number of both types some time ago. So in case you are happy with exact China copies I could send some at a tenner per bearing plus shipping.
The two bearings at the left were INA , the darker cage the oldest type and a bit different design, the two at the right are China supplied.
I designed my "home made" conrods for same types 40/48/20 mm after I did a 460 cc Horex single with a Carillo special rod, same type.

Vic

 

[Black Flash]

The iko Nippon bearing company still lists them in their catalogue.
This doesn't necessarily mean that they are still in production, but worth a call with a well equipped bearing dealer.

 

[oexing]

The IKO Nippon co. only lists KT types. The critical design feature are the faces at both ends of the rollers. You get immense centrifugal forces on the cage when located on a crank pin. For this condition INA designed extra large faces on the KZ cages so they can float on the oil film inside the big end bore. The cage is NOT a close fit on the crank pin , instead it operates with about 0,20 mm clearance within the big end bore and needs these faces with oil film to be supported in the rod . Other types of needle bearings will not be suitable for this application.
Look at the darker older type INA KZK cage in my photo above, it had even longer faces compared to the last types. So I cannot tell from the PDF IKO pictures if their bearings may be suitable.

Vic

 

[Phil Hogg]

Thanks very much for the input guys, Oexing that point about the KZ cage design is the crux with these bearings thank you very much for the photograph. Nice looking rods by the way. I have some bearings of unknown parentage that I got from Simon Linford a few years ago, I will compare them with your photo tomorrow. I also have a Silver plated Ina used in Jawa speedway motors from a few years ago, unfortunately 35mm but will get it out and have a close look at it's design in comparison. David there are of course people who can do this but that's not much of a challenge and as I have a machine shop there is certain satisfaction in doing it myself, the Comet is technically long stroke but I am looking for a good capacity lift for a lot of bottom end grunt for my purpose.

 

[Bill Thomas]

What are you going to Phil, I am going 102mm, I have a carillo rod 1/4" shorter.
There was a vintage racer a few years ago, With a Matchless 84mm by 102 mm, Nothing could beat him !!.
Good Luck, Bill.

 

[Phil Hogg]

Hi Bill, I was thinking somewhere between 100 and 105, as I have yet to source a rod that will may determine the final choice, are you using full circle flywheels? I am planning heavy press fit parallel pin in Nitrided flywheels.
Best Phil.

 

[timetraveller]

That is definitely the right way to produce the flywheels and you can use a larger diameter drive side main shaft if you wish.