I finally got my Urraco parts, the timing belt, and the bearings. I just wonder; All the four bearings is the same right?

I bought directly from skf four bearings. This was the 3205 A-2RS1TN9.


A lamborghini workshop in Sweden sendt me the belt and one of the bearing so i could compare with the bearings from skf.
The bearing I got from sweden is totally different, from the others, and sais SKF 3205 D on the box.. and on the actuall bearing it sais SKF 3250 A 144 C Explorer.

Does someone know witch number is the right one? I need to know witch bearing to put on my car thats the best one..


Best Regards

Daniel Skulstadberg

Norway

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

Daniel,

FWIW, I did some digging and found the receipt for the bearings used in my car. They are SKF 5205 A 2Z bearings. So, steel shielded on both sides. I seem to recall that GTCP was recommending a 3205 they said was sealed on only one side. That doesn't make much sense to me on an SKF bearing you're never supposed to have to lubricate. Didn't sound good to me then so I ended up talking to local bearing reps, NOT SKF, and ended up w/ the 5205 because it was, I was told, sealed on both sides and had a high speed rating. I was not told that the contact angle differs from the 3205s - I was told it was an upgrade.

Now, looking at SKF's website (not sure why I didn't start there and then contact SKF directly many moons ago), I see:

Bearings with shields, designation suffix 2Z, are produced in two different designs. The sheet steel shields used in smaller bearings form a narrow gap with the land of the inner ring shoulder. Larger bearings as well as all SKF Explorer bearings have recesses in the inner ring side faces into which the shields extend.

Shielded bearings are primarily intended for applications where the inner ring rotates. If the outer ring rotates there is a risk that grease will be lost from the bearing once it reaches a certain speed.

Doesn't sound like what is needed for our cars. Personally, I think you should talk to SKF again. I plan to. They should know what was used originally and have recommendations on what to use now. They should also be able to explain how that compares w/ what the dealer sent you. You can then bounce what they say off the dealer ... Where you've ended up sounds reasonable to me based upon my level of knowledge (far, far from expert) and looking at SKFs website. But go to the experts and ask them to explain their choice. I understand why you're nervous - a bad choice could lead to big bills later. I plan to contact SKF!!!

Good luck!!! Sorry to not be of more help!! Let us know what you find out. And anyone else w/ more knowledge - please feel free to jump in :-)

Best regards,

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

Daniel, have you talked to this company? http://www.nomo.se/svenska/index.html
They helped me out with some old Alfa bearings once.

Daniel,

haven't heard back from SKF yet. Do you have any updates?

Btw, if your crank pulley is accessible at the moment, you can compare its diameter to that of the bearings. If the bearings match or are larger (or even fairly close) I think the bearing speed limit concern I raised is a 'red herring.'

Best regards,

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

Hello Bryan..

Thank you for all the info! I haven't contacted SKF yet, but i'm planning to call them today, as the time in Norway now is 4 o'clock in the morning

I have to call SKF in norway and ask them to do some digging, and try to find out what they delivered to the factory. My crank pulley is not available at the moment as I planned to purchase all the parts before the shop should fix it for me during may.. It's not easy finding people with lamborghini expirience in norway, but now a ferrari specialist is going to have a look at my little bull..

I will call SKF to day and try to find out what they delivered to the factory, and what's the difference between the two bearings i have recived..

If they don't know I have to wait and compare with the bearings in the car..

the bearings you used in your car was SKF 5205 A 2Z right? But you think maybe it is not the right ones? how long have you been driving with these bearings? any problems?

This does'nt sound right either.. and then there is the 8500 rph limit.. is that really an issue? I'm not planning on drive my urraco further than 8500 rpm..

I'm really confused about this, and hope skf kan help me tomorrow

This is a very difficult question!! I talked to SKF in Sweden, and they told me that my bearing 3205 A-2RS1TN9 was more shielded from dirt than your SKF 5205 A 2Z Bryan.. BUT my bearings is not capable of more rpm than 8500.. when the car does 8000 rpm, will the bearing have higher rpm since it is smaller wheel?

Your bearing SKF 5205 A 2Z is capable of 12 000 rpm, but not as shielded as mine, after what skf told me.. The guy I spoke with at skf would not reccomend any of the bearings before we knew what rpm the bearing have..

I'm all confused about this.. I have given the guy at skf the link to this tread and hopes he reads it, and let me know what he thinks. He was a nice really nice guy..

Do you have any news Bryan?

Best regards Daniel

Hi Daniel!!

I am in touch w/ SKF and am in the middle of discussing the issue. They are concerned that the shielded bearings will not seal the grease completely in our operating environment and in addition to dirt ingress they are worried about grease loss and premature failure of the bearing. Doesn't sound good at all!!! None of this was mentioned to me when I worked w/ a local bearing house to select a bearing. The bearing GTCP was recommending was not sealed one one side (or so I was told, don't have the exact bearing number) which set off the quest ...

IMO, it would help if anyone on the list knows how the crank pulley compares in diameter to the bearing. Anyone? Laust do you have info on the Jalpa? Does it use the same bearing btw? If the bearing is larger than the pulley then bearing RPM should certainly be limited to under 8000 RPM (how high are you going to rev your car Daniel :-)) and I think SKF would consider the 3205 A-2RS1TN9 THE choice.

I know this is frustrating and you'd like to get on w/ it. I am working on it as well and will keep you updated. At the moment, it sounds to me like I am going to have to replace the bearings on my car :-( That should be interesting. All the work I've had done on the car at shops I've ended up redoing myself - except the belt and bearing replacement ... why should they be any different. Of course I was the one who ended up chosing the 5205s.

Best regards and hang in there - the bit of driving I've done in my car (as I slowly learn and restore it and after I rebuilt and adjusted the carbs) has been a ball!!

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

Wow, sorry Laust!!! I am in too early and apparently not awake. The Jalpa has chain driven cams, no belts of course :-) Any P250 owners w/ info on crank pulley vs. timing belt bearing size? Or info on bearings used?

Thanks all!!

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

Hello Bryan!!

This turned out to bee quite a mess!

I had a long phonecall with skf in Sweden and he would not recomend either of the bearings, before we knew the speed the bearing would have at 8000 rpm.. No bryan, I'm not going to rev my car higher than 8000 rpm
But will the bearing rotate faster than messured on the tachometer??

When the bearing is bigger than the krank pulley it will rotate slower, right?
And if it the krank pulley is larger, the bearing will rotate faster?

You will change your bearings to the once I have ordered 3205 A-2RS1TN9?

How long have you ben using the 5205 bearing? Any problems with it?

Here is a picture of goobers urraco. he has completely restored the car and the engine, and he allso has a thread about it here at lamborghini-talk, and in f.chat..

It seems to me at the pictures that the bearing is smaller than the crank pulley, but I'm not sure.. Anyone fill in with the exact diameter?



More pictures of goobers car: http://aussieexotics.com/goober/urraco/engine.php

The car is really fun to drive, and im really looking forward to getting the work done