Tight main bearings

nottsSteve · Post by **nottsSteve** » Sun Feb 19, 2012 11:28 pm

Hi Dave
Although bearings were tight they were not so tight I couldnt rotate the crank by holding the axle.
I have noticed the spacer does seem a bit rough so have ordered new one.
Have received some new bearings from JSL but have not tried them in cases yet.
Also, the new bearings and even the old bearings are not a push fit on the new drive axle, had to use a puller to get the RHPs off. Although experimenting with them there cant be a lot in it as it didnt take a lot of heat (placed them in plastic bag in my hot cuppa)to get them to easily slide on the axle.
Couple of things Im not surehow to proceed with but will leave that until ive tried new bearings in cases
Thanks
SteveEdited by - nottsSteve on 19 Feb 2012 11:29:36 PM

nottsSteve · Post by **nottsSteve** » Sat Mar 10, 2012 5:41 pm

Have now tried two NKE bearings and after reading Dons and wosters postings and Daves (above) tried bearings one at a time. Outer on its own ran free. Removed outer and tried inner on its own and it too ran free.
Heated casing up again, froze the bearings, put both in with spacer and all locked up solid. Could barely rotate the bearings.
Not sure how youre supposed to pull inner bearing out to set end play so I used a piece of 3 thou feeler gauge between bearing and spacer when assembling, removed it after about 30 seconds and now all turns freely.
Thanks
Steve

clive · Post by **clive** » Sun Mar 11, 2012 7:02 am

The parts list for 49 single notes that a different spacing washer between bearings must be used depending on whether Hoffman or Skefko bearings are used. I realise that in the 55 engine the bearings are different as one is larger but the point I am bringing up is that AMC in 1949 found that different bearings needed different washers spacing them, possibly to ensure the outer part of the washer did not touch the outer race asI assume the spacing was all about keeping the inners which are fixed on the shaft correctly spaced.

clive · Post by **clive** » Sun Mar 11, 2012 7:11 am

quote: Not sure how youre supposed to pull inner bearing out to set end play so I used a piece of 3 thou feeler gauge between bearing and spacer when assembling, removed it after about 30 seconds the free turning of your bearings will now rely entirely on the interference fit of the inner bearing in the case. Its a tight fit on the shaft so any movement in the shaft will tend to move the bearing across. The shaft and whole big end assembly is pulled over to one side by the shock absorber spring so perhaps this would work. Personally I would further investigate the spacer size as I noted above and put the bearings in flush to each other.

nottsSteve · Post by **nottsSteve** » Sun Mar 11, 2012 10:50 am

Hi Clive
The washer sits loosly on the shaft. One side of the washer rests on the inner race of one bearing and the other side of the washer rests on the inner race of the other bearing.The washer touches nothing else apart from the 2 inner races.
Ive tried fitting the bearings without the washer and it all turns fine.
With the spacer fitted it locks up or goes tight. This hgappens with the old washer and the new one from Jampot Spares.
With the spacer fitted and a couple of thou play between spacer and bearings and it runs fine..
Another member suggested on here that as the cold bearings expands and the hot case contracts the assembly is pushed up against the face of the outer case which either almost locks the bearings or at best makes them run tight.
Theres a slight recess in the outer case which i presume is so the inner race doesnt touch the case as it spins which would counter the above explanation. But it is only a slight recess.
Steve