Journals

[bh.sprint]

Message for Peter W.-- York

Rockrome Engineering Co Ltd.

01519280080

A M Philpot Luton

01582 571234

I'll put Rons number on the message facility or phone (Fahron)

Brian H. I've not tried these they are from the addresses I picked up at Stafford

[Roger James]

I've been using Rockrome Engineering for years having them rechrome crankshaft journals including those used on my Arrow production racer, if you decide to use them best to send the crank webs off early if part of an engine rebuild because the process can take a few weeks to be completed. Jess

[john.whiting]

Surprising you can run rollers on chrome......conventional wisdom is that the chrome will waste away...........Ive had it happen on gearbox mainshafts,and front bearings(in trucks).....maybe they are using a new process.

[bh.sprint]

Hello Roger,

Thanks for the information re Rockrome. The last jounals I had done were by Beckett and Gardiner in Sheffield,before they were taken over/ close down. There were enough to do 2 or 3 engines but I only have one left now. So I'm looking to have more done for the engine Ron is doing at the moment.

Brian.

[petewatts]

Thank you so much for your information re chroming ,but as i have bought two special bearings from Keith Harding which are 5 thou over size (on the inner sleeve ) what i need is somewhere that can grind the journals to suit .Do the individual cranks need to be split or can they be ground intact , also any thoughts on big end replacement .Thank very much Pete

[nevhunter]

I'm surprised you are getting away with chrome and rollers running on it. You normally need a ball race steel for the bushes and a Case hardened nickel alloy steel pin . I've never seen chrome used successfully unless it's a plain bearing running on it. With Chrome you need to heat treat it straight away or you risk hydrogen embrittlement which will make even large dia pins just crack right through without much load. Nev

[Roger James]

Nev, I don't have the big end pins chrome plated but the three journals on the crank webs that the crankshaft bearings slide on to and the larger journal for the central oil seal(s) when deep grooves have been worn into the metal. Jess.

[nevhunter]

Fine roger. Might still be worth doing the heat treatment for embrittlement. I found out the hard way with a race motor that didn't even get to be driven, and it was crack checked prior to being hard chromed. It's a common problem in the aviation industry. Even stripping chrome electrolytically needs to be considered. . Nev

[bh.sprint]

Name tag engineering do work on two stroke engines, their work on the Leader/Arrow engines is said to be good. They may be able to machine the journals/shafts to fit the smaller bearings but I think the only way be get the required accuracy is to split the assembly and machine the shafts separately.
To get the bearing to slide onto the shaft but still hold firmly enough not to slip/spin requires a tight tolerance in the order of .0001/2 '' . I finished mine off with a slip stone to take the last .0001/2 off and get a tight fit on the inner race of the bearing. It's been OK for 20 years and nearly 18,000 miles.

Brian H.

[nevhunter]

Yes, the coupling in the centre of a TS twin has always been a critical design issue. It was a problem not really cured in the 250 Villiers motor in the Excelsior Talisman twin. It has to be tight and aligned perfectly and the seal (s) are inaccessible without dismantling (usually). Nev