Hi Daniel!!

Yes, it can be frustrating!! I know I have a lot to learn!! This is what I can tell you. Several Lamborghini Dealers have told me the replacement bearing for the Urraco is an SKF 3205 D. The trailing D or in your case A per SKF's website are indications that there is something special about the internal design of the bearing. A indicates there are "no filling slots" and D indicates a two piece inner ring.

Try starting with :

http://www.skf.com/portal/skf/home/p...newlink=1_3_34

And looking under

/ Products / Interactive Engineering Catalogue / Rolling bearings /
Angular contact ball bearings / Double row angular contact ball bearings /

The 2RS1 TN9 bearings SKF sent you have:

2RS1 - Sheet steel reinforced contact seal of acrylonitrile-butadiene rubber (NBR) on both sides of the bearing

TN9 - Injection moulded snap-type cage of glass fibre reinforced polyamide 6,6, ball centred.

In the product table, they are also marked:

MT33 Grease with lithium thickener of consistency 3 to the NLGI Scale for a temperature range –30 to +120 °C (normal fill grade) .

Makes great sense to me to be sealed in the 'dirty' environment the bearings have to operate in. I remember I went w/ a double sealed bearing as well.

The thing I wonder about is the speed rating of what SKF sent you. If you look in the product tables under Angular Contact Double Row bearings, you'l find several flavors of 3205 bearings. All have the same dimensions: 25mm inner x 52mm outer by 20.6 mm deep. All have the same load and fatigue ratings. The differences are speed rating and internal construction.

1) Speed ratings. The bearing SKF sent you has a max speed of 8500 RPM. Not sure if the bearing is smaller than the crank pulley - it is certainly smaller than the cam pulley, but that turns at half the rate fo the crank pulley if I'm not mistaken. I remember this lower limit made me nervous, but several knowledgeable folks told me not to worry about it. Nonetheless I did and went w/ one of the other 3205s which had a max speed of 12,000 RPM.

More knowledgeable folks in the group (I hadn't found this site when I was looking for bearings) can tell us if its worth worrying about - Laust? This would also be a good question for SKF!!!

I believe I was tempted to settle on a 3205-2ZTN9MT33, but I am no longer certain as I seem to have misplaced the notes. I know I settled on a speed rating of 12,000 RPM.

2Z - Shield of pressed sheet steel on both sides of the bearing.

Looking at SKFs site, yours is a much better seal so the speed rating point is probably moot!!! Now I'm worrying - have to see if I can locate markings on my bearings :-)

I can't find a 3250 A 144 C in SKF's product tables, so I'm not sure what to tell you. Again, I think this is a question for SKF!!!

So, my suggestions are to call SKF and ask them about seals and speed ratings. They should have data on the original Urraco bearings as they made them!! Meanwhile, also see what the more knowledgeable folks on this site have to say on the subjects.

Hope that helps ... a little.

Best regards,

Bryan
'74 P250S S/N 15622
Indianapolis Indiana USA
blissinindy@yahoo.com