TR2/3/3A Con Rod Bearings TR3

[prb51]

Wondering if there is a major difference in wear ability/performance between the Bi metal Con rod bearings and the Bi metal bearings.
I've noted one vendor carries the Tri M and all of the other vendors just list bearings so I'm assuming they are bi metal.
I'm going to replace my thrust washers (still in spec but only) so might as well do the big ends. I'm hesitant to do the mains with the motor in place (worried about the oil seals) although I've heard from some who've done that with the engine in the car. Anyone else done the mains with the motor in place? My concern is getting the felt packing in properly and the metal seal positioned right from that position. Right now no leaks fore/aft and I'd hate to bung that up.
I'll also inspect the oil pump to see if the rotor/vane are original and in spec. If not original then I'll screw pin the vane as per Kas's suggestion.
I'll try and do better taking some pics this time during the process.

 

[hondo402000]

just a question of why you would be replacing the bearings? Low oil pressure or you just want to? You might want to check the clearance with plastic gauge, I also heard some not so accurate readings with it but better than guessing and replacing bearing that are not worn out.

I was always good at replacing things that didnt need it

 

[prb51]

Hondo,
The thrust bearings are at the far end of spec. Anyways, never had the pan off so I'd like to check the oil pump specs/vane pin. So easy to do the BE bearings might as well. The factory shop man recommended changing every 30K for longevity. I'll plastigage and mic everything.

 

[martx-5]

Why are you replacing the thrust bearings if they are still in spec?? How did you measure it, and what was the dimension??

 

[prb51]

Art,
Crank end float new .0048 to .0117 and it's time to renew although I know many run them beyond .0117. Measured at the crank pulley with a micrometer dial gauge after pushing the crank rearward then zeroing gauge and pressing the clutch inward forcing the crank fwd.
I'm going to replace them, easy job, my question was about the Bi vs. Tri metal bearings. Any opinions/experience with these?

 

[martx-5]

Last week I talked to Ken Gillanders from British Frame & Engine about main and con rod bearings. I don't remember all that he said, but basically he mentioned that there is only one primary manufacturer of bearings that fit these engines. He loves to talk, and there was some mention of tri-metal bearings, but I forgot what he said about it. I'd give him a call, as he has extensive experience with these items, and can also supply you with whatever you need.

 

[tomshobby]

One of the forum vendors has King tri-metal bearings.

https://www.bpnorthwest.com/.sc/ms/cat/TR3-4A--Main%20Engine%20Components

 

[Deleted member 451]

On King's website they reccomend their new Bi-Metal bearing made with Alecular. They give some pretty good reasons.
I don't thiink you can make enough power with a TR3 to need Tri-Metal bearings and Bi-Metal bearings have better heat restance.

 

[prb51]

Good information from all.
I talked to Ken G and checked the King site and will use the bi metal units. Ken indicated many racers areswitching to the bi metal units too.
This was a new subject for me so I appreciate the input.

 

[TR3driver]

On King's website they reccomend their new Bi-Metal bearing made with Alecular.

Just curious, Bill, have you EVER known a vendor to NOT recommend their "new" product ?

And to think, all these years I've been using "old and inferior" /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

 

[Andrew Mace]

An interesting article on engine bearings ; read / absorb at your own risk. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

Back when the Triumph Herald was new, the single-carburetor 948cc engines got cheaper bi-metal bearings, while the "rip-snorting" dual-carburetor 948cc engine (admittedly with about 20% more power) got copper/lead/indium bearings. But that was circa 1959, and a basic engine design some six years older than that odds are metallurgy and lubrication technologies have allowed for much improvement in the last 50 years or so!