Lotus Europa Twin Cam tapered rear axle/housing bearings

[TurboFource]

- Tapered 30206 bearings will fit in unmodified Twin Cam rear housings.
- The issue is the outer bearing is "proud" of the housing making sealing it problematic and creating assembly issues without modifying the trailing arms.
- The existing inner seal will work fine.
- I did not feel there was enough of a land in the housing to machine the bores deeper and I did not want to modify my housings.
- You will need to set bearing endplay by either machining a new spacer between the bearings or using shims (I used machine tool arbor shims).
- I set my endplay at .002 (I used an infrared thermometer and heat gun to warm parts to "operating" temp too make sure they still turned freely.)
- Since I am attempting to run gear oil, we 3D printed carbon fiber reinforced nylon "seal" holders that hold seals that seal on the flat face of the bearing and the O.D. of the    flange. (These "seals" will not work for most people as I eliminated the outer spacer between the bearing and flange to gain full spline engagement.)
- It would be easier to use grease and possibly one of these options designed for 30206 bearings:
  https://www.eabs.co.uk/product/14250
  https://www.ebay.com/itm/144441180205
  You could probably cut out your own felt grease seal that would run on the outer spacer if you took efforts to center it on the stub axle.
- This will move your housing by approximately a 1/16 - 1/8" towards your fender and your brake drum away from the backing plate by 1/16" (The outer spacer could be machined to eliminate this.).

[Dilkris]

JB - over to you. 

[BDA]

I'm having trouble visualizing how this works...

First, I assume the outer races are positioned against the shoulders machined in the upright originally designed for the original ball bearings.

Is the inner bearing set on its race by the shoulder on the stub axle?

Presumably the outer bearing is set by the hub against the bearing since you deleted the outer spacer.

Your inner spacer is sized to the distance between the outer races?

I'm confused by your 0.002" endplay. It seems there is none on a front bearing setup. Should you have that much? Aren't you worried that lateral loads will beat up the assy? It is adjusted by the stub axle nut, right? So you are no longer going to torque that nut (which makes sense)?

I know it's been mentioned before but I think grease would work better here and that might "encourage" you to block off the lower leg of the upright.

Maybe I'm missing something. I hope you can set me straight.

[TurboFource]

Both inner races are against the bottom (shoulder) of the inner machined bearing bores. The .002" is how much longer the spacer is than the distance between the inner races of the bearings (this allows for thermal expansion). The nut is still tightening everything together as original. The endplay on your front bearings is controlled by how tight you tighten the nut.....

Gear oil is a better lubricant and allows for a much higher speed rating than grease on the same bearing...so I am trying it hoping for increased longevity...

[GavinT]

Turbo, this looks impressive but I'm also having trouble visualising some stuff.

Given the outer bearing race stands proud of the ally housing, did you enlarge the hole in the trailing arm?
You mentioned "without modifying the trailing arms" but it wasn't clear to me whether that's what was done.
If so, is the brake backing plate now performing the function of retaining the outer race?

I'm figuring the trailing arm won't willingly go over the proud bearing race without enlarging the hole, but may do so if 'persuaded' during installation until it snaps into position.

Not wanting to wade into the gear oil / grease / longevity debate, I just reckon oil makes increased demands as to the lubrication sealing needs. If the seal fails, there seems to be a reasonable chance of oil being flung onto the brake shoes.

Still & all . . I like it.

[TurboFource]

This modification is not for the meek as I did have to modify the trailing arms for assembly purposes. I thought about this as part of them needs to be removed, but I put the cut out piece back in on assembly to retain my seal holders. I also figured that the brake backing plate has enough strength to resist any rotational forces ( if my turbo motor makes enough power to bend them then I have really accomplished something )

[TurboFource]

When I researched owning a Lotus Europa, I felt the current rear bearing longevity was unacceptable (and front sway bar placement).
I am trying the gear oil because if I don't I will always wonder if I could make it work. I may be switching to grease if it doesn't, but in either case I may
not ever have to change rear bearings again (look at how long differential bearings running in gear oil last).

[cwtech]

Turbo, this looks impressive but I'm also having trouble visualising some stuff.

 Is the brake backing plate now performing the function of retaining the outer race?

If I'm understanding this correctly, the outer races (bearing cups) are retained laterally by the inner races (bearing cones).  ....The cups are bottomed-out against the shoulders in the housings so side-to-side movement is restricted.   

I am concerned about leakage around the O.D. and/or spinning of the bearing cups if not installed without sealant or locking compound.  ....Of course, unless the bearing seizes, the cups should not rotate.

[TurboFource]

I used Loctite 638 to make sure the outer races (cups) will not move.
The outer race of the outer bearing is also held by my seal holder as it is compressed by the trailing arm.

The most anything can move is the .002" endplay before things warm up.

[TurboFource]

Note the difference is speed rating for oil vs grease....

[BDA]

That tells me that you could go 448 mph with grease! 

[TurboFource]

Or 600 with oil then!

[Kendo]

So, you’re saying there’s a safety margin?

[SwiftDB4]

I'm still trying to figure out how this works too. Don't count on Nylos seals containing oil. I have them on my GT40 axles and they are only good for grease. Even at that I have to regrease and adjust my bearings every 6-10K miles.

[TurboFource]

I am not using nylos rings, I suggested they could be used for grease.

I am using these: https://www.mcmaster.com/1161N69/