Got the crank and new rods together at last and dry fitted in crankcases. I turned down an old Superblend and roller bearing to make assembly easier and now need to know about sorting the end float. Some say you don`t need to do this if using a roller one side and a Superblend the other ? There is `float` but I have not measured yet. I know `shims` are available in various sizes but is there a preference where they are to be fitted ? Should I be fitting the oil pump parts and the alternator etc .before measuring . I want to get it right so your info would be welcome.
Cheers
Wayne.
So just to get it understood…
So just to get it understood ( for me ) I have purchased a NJ306-E-XL-M1A C3 FAG ( Superblend ) bearing for Driveside and a 6306 C3 FAG ( 8 Ball ) for Timing side. Is this not right ? And are you saying that although there is Crank End Float no shimming is required ?
Thanks
Wayne.
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Phil is right , the engine…
Phil is right , the engine designers knew what they were doing. The 500cc motor does not gain anything from the change to the bearings that the bigger motors needed. Shims are just a bodge anyway and can break up in use unless provision is made to put them out of harms way. I would rather run the motor on 2 uprated ball races than do what you propose !. It has been done.
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Bearing Choice
Wayne........your choice of bearings is absolutely fine. A quality 8 ball on the timing side will be OK. Fittings these two bearings will save the hassle of shimming up the crankshaft to get the correct end-float. Plus cut down on internal friction.
The Bracebridge bike crankcases were machined to give 8 to 10 thou of end-float cold.
The recommended max, for end-float, is 20 thou.
The late John Hudson told me that he frequently pulled apart Commando engines and found 40 thou gaps.
I have rebuilt dozens of Dominator engines and generally found the crankshaft end-float between 12 and 16 thou. The exception to that was a bottom half glued together with Green Hermatite.
Robert is quite correct about the twin ball bearings engines. This was a trick used by the race lads to cut down on the internal friction that increases when using double rollers. The draw-back being the drive-side bearing always needed replacing after a race day.
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Thanks Phillip and all…
Thanks Phillip and all concerned. On reflection and having taken note of your previous advice I paid a visit today to my Bearing supplier and ordered a 10 Ball for the timing side !
Made another boo boo by fitting new Con Rods and then finding out they need to be removed before Balance factoring ! I found Basset Down Balancing in Hungerford seem to be the nearest to me in Fleet Hants ( 31 miles away down the M4 ) . Can you advise on any others AND is 70% the right factor for my Dommi 88 500cc ?
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10 ball bearing for timing side
Hello Wayne,
Could you share the make, part number and supplier for the 10 ball bearing.
I am rebuilding a 650SS engine and would like to install this bearing as opposed to a roller and the hassle of shimming.
Kind regards
Phil
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Wayne hello - Is your 88 an…
Wayne hello - Is your 88 an early Wideline (with a small valve head) , a later Wideline or Slimline (with a large valve head and Daytona cam) or an SS with the all important SS cam, h/c pistons, SS pushrods and followers, Competition magneto, Twin carbs etc. The reason I ask is because having ridden and played with 88s all my life unless you have an 88SS "balancing the motor" will be an unnecessary extra cost. On most models an MJ30 timing-side ball bearing with C3 clearance will be adequate with the 10-ball notched ball bearing good in the SS. If you are building a racer or road burner good luck. Howard
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Hi Howard, I have an 88…
Hi Howard, I have an 88 Wideline 1959. Not up on weather it`s big or small valve as this is my first Norton ! It`s standard as far as I can see apart from what I`m told is an SS cam. Not going to race it but want a nice cafe racer. It`s been rebored, new pistons and con rods/shells, re-ground journals , new guides and G+S valves, push rods, NOS flat followers so far. 10 Ball bearing on order. Strangely my intentions were to heave the Norton motor and build a Triton before I got interested in doing the Norton motor.
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So in 1959 it would have had…
So in 1959 it would have had a Big Valve cylinder head. These heads are easily identified in that none of the fins on the head are vertical (ie they all lie horizontal) and the inlet ports where the manifold fits are vertical. Vertical fins behind the exhaust ports signify a Small Valve head and horizontal inlet ports, where the manifolds fit, signify a semi-downdraught head. If your new con-rods are Norton and the pistons are UK made then you shouldn't need to re-balance. If the pistons and rods are much heavier than Norton ones it may be that re-balancing is required, If you decide to split the crankshaft before re-balancing use a set of new crankshaft nuts. Cheers, howard
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Rods are from Thunder…
Rods are from Thunder Engineering and Pistons are Gandini ( Italian) from Andover Norton. I have matched the pistons in weight and the rods are matched weight wise from Supplier so I have taken the lot in for Balance factoring. I had the crank apart to check sludge trap ( clean ! ) and used new nuts/bolts/studs too. Loctited and staked / tab washered. Two weeks to wait now before I get the Crankshaft back ! Photo shows the bike when I first picked it up .
Cheers
Wayne.
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So you're quite correct. …
So you're quite correct. The Thunder Engineering con-rods are heavier than stock 88 and the Gandini pistons are a good bit heavier than Norton and AE. Are you fitting twin carbs ? It sounds as though it will make a decent racing engine......food for thought ? I'm pleased to hear that you've gone for the notched ball race on the timing side. Many people don't of course and regret it when the 7 balls wear out early. Cheers, Howard
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Not going to Race it Howard…
Not going to Race it Howard but aiming for a good reliable `Cafe Racer` . Planning to use a Belt drive , electronic ignition and a single carb . Undecided on what to use but leaning towards a new Mikuni but I need to do some homework yet. Thanks for showing an interest and comments.
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Fitting twin roller bearing to a Model 88 is a waste of time and effort unless you are planning to use your bike for serious track racing.
Fit the best roller bearing you can get to the Drive-side and an upgraded ball bearing to the Timing-side. RHP also used to offer a heavier duty ball-race RHP M306 of the notched type that employs 10 balls. There are modern equivalents around.
This set-up will probably outlive you on an 88.
All my 650 and 750 Nortons used an NJ306E C3 on the Drive-side and M306 on the Timing-side. No messing about with shims for me.