ls3 pilot bearing and tremec tkx q

[eliot]

Hi, anyone know which way round this bearing should go into the crank - it’s not symmetrical, so wary of just bunging it in.
Googling around and the bearings look nothing like this.

It’s an LS3 with a Tremec TKX going into a kit car.

photo a:



photo b

[TwinKam]

Can't really see into that bearing in rhe photos... does it have a plastic ring at one end?

[eliot]

not sure - it’s a friend’s car. What’s the relevancy or what am i looking for.
i don’t recall seeing anything on the bearing.

[GreenV8S]

I don't know that engine, but based on the pictures it seems to me the lower picture must show the side that faces towards the clutch. Otherwise, when the bearing is installed the inner collar would rub against the bottom of the recess in the crankshaft. Since the inner collar needs to spin with the gearbox input shaft, this would be the wrong answer.

[eliot]

GreenV8S said:

I don't know that engine, but based on the pictures it seems to me the lower picture must show the side that faces towards the clutch. Otherwise, when the bearing is installed the inner collar would rub against the bottom of the recess in the crankshaft. Since the inner collar needs to spin with the gearbox input shaft, this would be the wrong answer.

It’s a needle bearing, so it’s all stationary in the effect.
However it is the lower photo, as I asked on a ls chevy facebook page, and someone on there is familiar with the bearing.
The giveaway that i didn’t spot, is that they one side had a chamfer/lead and the other side doesn’t.

Thanks…

[GreenV8S]

eliot said:

It’s a needle bearing, so it’s all stationary in the effect.

That reasoning doesn't sound quite correct to me. The needles bear on the inner race, which is stationary with respect to the gearbox input shaft. It's an integral part of that shoulder we can see sticking out. Is that's in contact with the crankshaft then it will cause friction and wear, defeating the point of the pilot bearing. Anyway, it's no problem, since you're proposing to fit it so that shoulder won't contact the crank.

[stevieturbo]

Has someone mounted the normal early LS needle roller into some sort of weird outer fixture ?

It is just weird, doesn't look OE at all

[TwinKam]

eliot said:

not sure - it’s a friend’s car. What’s the relevancy or what am i looking for.
i don’t recall seeing anything on the bearing.

They sometimes have a plastic ring as a seal to keep grease in/dirt out of the bearing, this should face out when fitted, ie towards the gearbox.

[eliot]

stevieturbo said:

Has someone mounted the normal early LS needle roller into some sort of weird outer fixture ?

It is just weird, doesn't look OE at all

yes that’s what it seems to be. I asked on a FB group and by coincidence a chap that builds the very same kit (ak cobra) has used this very pilot bearing and pointed out the chamfer to me.

[eliot]

GreenV8S said:

eliot said:

It’s a needle bearing, so it’s all stationary in the effect.

That reasoning doesn't sound quite correct to me. The needles bear on the inner race, which is stationary with respect to the gearbox input shaft. It's an integral part of that shoulder we can see sticking out. Is that's in contact with the crankshaft then it will cause friction and wear, defeating the point of the pilot bearing. Anyway, it's no problem, since you're proposing to fit it so that shoulder won't contact the crank.

it’s a needle roller thats been pressed into a sleeve that’s then pressed into another sleeve, so it’s all stationary in respect to one another.

[GreenV8S]

eliot said:

it’s a needle roller thats been pressed into a sleeve that’s then pressed into another sleeve, so it’s all stationary in respect to one another.

It does not look that way to me.

Starting frpom the outside I can see a housing, the outer race pressed into it, the seal between the inner and outer races, and the inner race. The inner race has a shoulder which extends beyond the housing.

The inner race rotates with the gearbox input shaft. It will be moving relative to the outer race, housing and crankshaft. If it's in contact with the crankshaft this will cause friction and damage to it. If the bearing is oriented so that this shoulder is at the bottom of the hole, I expect it will be in contact with the bottom of the hole ie in contact with the crankshaft.

I expect this is why the bearing assembly is offset this way, so that when it's oriented correctly the part of the bearing which is at the bottom of the hole is spaced away from the crankshaft.

[eliot]

look at photo “a” with the writing on the bearing - that part is stationary and is pressed to the thing with the slot in it, which is pressed into the outer part which gets pressed into the crank - none of it rotates.




essentially it’s a standard needle roller bearing pressed into two adapters - for what reason i don’t know, but im assured its a known thing by a builder who’s put many of them together

[GreenV8S]

eliot said:

essentially it’s a standard needle roller bearing pressed into two adapters - for what reason i don’t know, but im assured its a known thing by a builder who’s put many of them together

I'm not sure why we're still discussing this. The innermost component shown in photo b clearly shows an inner race, not exposed roller bearings. The inner race is an integral part of that protruding shoulder and will rotate with the gearbox input shaft. The picture clearly shows a seal separating the inner race from the rest of the assembly.