2 1/2 crankshaft bearings..

Fossil
Posts: 380
Joined: Sat Feb 13, 2016 5:08 pm
Location: Helensburgh, Argyll

Re: 2 1/2 crankshaft bearings..

Post by Fossil » Mon Feb 12, 2018 1:43 pm

Guys

Do you know what bearings Barry has been supplying in recent years? My SP engine was rebuilt in 2011/12 using Barry for parts. The answer to the question may be available here, if not I'll ask him. We also fitted a set of brace bars from Barry because of other faults found.

It's worth noting the history of this engine in this topic; it had been messed about by the previous owner who participated in amateur motorsport (sprints and hillclimbs) in the 70s, and it required attention when I bought the car in the early 80s. It was then rebuilt by Oselli around 85, but there was still a problem after that, it felt quite rough beyond 75, although it would cruise fairly happily at 85 to 90 with adequate power. It was difficult at that speed to distinguish engine from road vibration. Work and family matters prevented further attention until after I retired in 08, when a fine vibration at 2000 to 3000 rpm became evident. When dismantled then, some 20,000 miles from the Oselli rebuild, all the bearings were worn through to copper backing, the cause being unbalanced rods. The likely cause of the latter being more likely the previous owner's tinkering than Oselli's errors perhaps, although the latter had clearly, at the very least, not balanced the engine at all.

The engine balancer in 2012 had to remove metal from both ends of several rods, and also had to add heavy metal to some of the crankshaft webs to achieve a good result. I've thought about this a lot; which of the two would be more likely to have had more than one set of con rods to play with at the same time, and mix them up, accidentally or intentionally?? We'll never know the answer now. But apart ftom the engine woes the rest of the car had been very well cared for and that still shows. It is very well put together and feels much more solid and rattle free than most. It also has the later rear axle and had a nearly new gearbox, since replaced.

In my ownership from the 80s onwards the car was never subject to hard use through several years as my sole daily transport in the 80s, followed by purely recreational use with low annual mileage throughout the 90s and 00s.

The significant points worth making from all this are that,
first as Russ says, unbalanced rods cause premature bearing wear within as little as 20k miles, and also
second, that in this case there was no more serious symptom of severe bearing wear than the fine vibration at 2000+ rpm, felt mainly by the bum; no knocking noises or more major vibration at all.

Indeed the last thing I did before the engine came out was to take the car up the old "Rest and Be Thankful" hill climb course, mostly in second gear, for film about the course being made for the new Glasgow transport museum, the Riverside Museum. The oil pressure was "adequate", say 20psi at idle and 35 to 40 hot, IIRC, but, it had the 3/8 inch spacer under the oil pump relief valve spring modification from the time I acquired it. So did the oil pump mod disguise the bearing damage?

The current state is that the crank has been reground, all the bearings replaced, the rods, crank and new pistons all rebalanced plus the brace bars from Barry and the relief valve spring spacer too, and she is now as sweet as a nut at last, although regular readers will recall that the crank vibration damper gave up during the last outing of the 2017 season. It had had more than its fair share of vibration to absorb without doubt. But that is now sorted too and the smooothness is restored, again.

Will stop now!

Regards

Geoff

daimlersteve
Posts: 279
Joined: Wed Mar 09, 2016 11:20 am

Re: 2 1/2 crankshaft bearings..

Post by daimlersteve » Tue Feb 13, 2018 2:48 am

The word just in from the machinist is the rear main ( std. bi-metal as all i could find in the length required ) is 1/4 thou different from the cu/lead version ,though both are King Bearings and the spec sheet shows them to be the same. - the increased clearance in the 3 bearing bmc A series is supposed to be in the crank grind size ,not the bearing ---- ???? anyway we are progressing slowly towards the final goal.
steve

Sonus
Posts: 146
Joined: Wed Apr 13, 2016 2:19 pm

Re: 2 1/2 crankshaft bearings..

Post by Sonus » Mon May 14, 2018 4:00 pm

Anyone had any luck sourcing high quality crank shaft bearings?

tjt77
Posts: 371
Joined: Wed Mar 23, 2016 7:01 pm

Re: 2 1/2 crankshaft bearings..

Post by tjt77 » Tue May 15, 2018 7:21 pm

reply to Fossil:- when you have an engine that has 'known issues' the best route is to have everything measured and re-machined as required to bring it back to original specifications... balancing is also very important .. when all the rotating components are properly balanced to with .5 gram it will usually double the life of the bearings .. as quoted by Russ.. if the con rods have variation in weights , the bearings can wear out in 20k miles or less..
commonly its the intermediate mains that wear out first.. and generally they show wear by 40-50k miles in the saloons when in 'normal' service....
in your shoes id either source another short block assy ... and start afresh ( if you have the steel main caps as supplied by Barry, these can be re-used on the replacement block ... transfer them over and have the lower end line bored when preparing the cylinder block.
if re-using your existing block, then get it properly measured on all surfaces, line bore the main bearings housings and anything else that is out of spec.. and have ALL the moving parts balanced properly. When 'short cuts' are taken on these engines, the end result is never good..

Bearing supply :- as I understand it from my communications with others, 'king bearing' have said they will produce the bearings in tri metal ( lead copper) format later this year.
I did have some lengthy communication with the research engineer at Vandervell last year (back in business under ownership of Mahle Motorsports division) and he did find the original blueprints for the bearings .. BUT.. the tooling has been lost.. they are prepared to make them again, but the customer has to pay cost to re-tool ..which is quite costly ( estimated bearings cost if tooling is written down over 20 sets) would equal close to 900 UKP per engine set .. Ive been informed ( but have not verified) that the standard king 'lead copper' (tri metal) bearings are good for apporx 6,000 PSI.. whereas the original vandervell VP2 are good for 12,000 psi ..King 'racing' bearings are actually built to withstand higher loads than the VP2 ( 17,000 psi as I understand) but the are unlikely to be available . the current king/county bi metals (reticular tin alloy) that normal suppliers have in stock are good for approx 5,000 psi.. these do not hold up for long if full power is used..furthermore they are hard on the surface, which means a regrind is always necessary when the bearings need replacement .. generally the VP2 allow for at least one set of bearings to be replaced as a routine service 'freshen up' of a slightly tired engine ( reason being the lead indium facing is relatively soft..but the bearing structure is strong and durable, due to the steel backing combined with copper overlay under the lead indium facing)
most of the people who are using these begins for racing either modify 'other' bearings to fit..or re manufacture the whole lower end with billet crankshaft and rods using bearings to fit the specification.. this of course requires very deep pockets .. with well heeled people not batting an eye at spending $18-22k to produce a 'winning' engine..

Barry Thorne kindly supplied me with a couple of sets of original vandervells for one on my engines (i had the crank sized to fit the undersized bearings) as well as a set of old stock Std 'glacier' aftermarket bearings in lead copper format ( I believe close to equal to the originals) so Im covered for current re-builds.. although I had to use some king 'bi metals' for a customers engine rebuild.. which is for road use only.. limited usage..so should be just fine..
appologies for typos.. computer does not always follow protocol..

daimlersteve
Posts: 279
Joined: Wed Mar 09, 2016 11:20 am

Re: 2 1/2 crankshaft bearings..

Post by daimlersteve » Wed May 16, 2018 7:02 am

Good writeup tj. covers all aspects. my research was negative so altered king 1275 mini units in c/lead. sonus ' engine builder has researched and came up with the same option though not followed through with the mods required it would seem ( still on the lookout ). Barry also sent me some old stock but the surface was compromised so i re-invented the wheel. . Steve.

Ps. had a call from the machinist today requesting a head and studs to do a full tq. down and then check if the block deforms --- ahh its only money , then we'll know ( i dought there will be any change but this way we'll prove it. Also today rebuilt the tube SU Manifold with steel flanges fully welded rather than the previous -- Tube epoxied to the alloy ones i'd used. fit and forget now.

tjt77
Posts: 371
Joined: Wed Mar 23, 2016 7:01 pm

Re: 2 1/2 crankshaft bearings..

Post by tjt77 » Sat May 19, 2018 3:23 am

question for steve:- I no longer have any bearing catalogues, so researching 'close' equivalents is not easy.. On the 1275 BMC A series rod bearings :- what has to be modified to make them suitable ? are inner and outer diameters same or close ?

daimlersteve
Posts: 279
Joined: Wed Mar 09, 2016 11:20 am

Re: 2 1/2 crankshaft bearings..

Post by daimlersteve » Sat May 19, 2018 11:25 am

1275 bearings are wider. I made a jig to hold them in pairs, then machined them in the lathe. The mains are also wider so the same situation applies.If used in a saloon block the #2 and 4 can be made wider than std ( which is the same as the centre main in the packet of Kings. ) I could not find a bearing long enough to replace the rear main though so had to be satisfied with the std. king in that position.

daimlersteve
Posts: 279
Joined: Wed Mar 09, 2016 11:20 am

Re: 2 1/2 crankshaft bearings..

Post by daimlersteve » Thu May 24, 2018 11:04 am

Damit,
the saloon block deforms just over a thou when measured with the head bolted down after honing (without the head obviously ). this suprised me though it didnt the machinist. Many usa v8s deform so trq plates are needed to maintain correct dimensions. This measurement is with the block bored to +150 so i'm not sure what a std or +40 would do... I think i'll run with it as the mtr. is not an all-out race version.
steve

Sonus
Posts: 146
Joined: Wed Apr 13, 2016 2:19 pm

Re: 2 1/2 crankshaft bearings..

Post by Sonus » Sun May 27, 2018 9:53 pm

I can have a 3/4" thick torque plate made for £70 on a large water cutting machine. Would you recommend me doing this Steve? Or are the benefits marginal?

I have source a set of NOS Glacier stock size bearimgs from Barry Thorne :)

daimlersteve
Posts: 279
Joined: Wed Mar 09, 2016 11:20 am

Re: 2 1/2 crankshaft bearings..

Post by daimlersteve » Sun May 27, 2018 10:21 pm

It would need to be 65mm to be of benefit. There is a special grade of alloy used that does not deform when machined.
Its all a tad expensive so i'll run with it as is.
steve

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