Visual differences between S2 & TCS hub carriers

[Grumblebuns]

I never knew the differences between the S2 and TCS hub carriers. Having the two available for comparison I decided to take pictures showing the differences. This may help someone in case he comes across one in a swap meet. This is some of the obvious visual differences that I noticed without using calipers or a side by side comparison.

1. The S2s have LEFT/RIGHT embossed on the casting, the TCS does not.
2. The S2s have two separate holes for shock mount and the lower link bolts, the TCS only one
3. The S2 hub mounting holes are a trapezium (US definition), there are no parallel sides. The TCS hub holes are spaced as a rectangle, equally spaced holes.

The only obvious differences visible by having both side by side for comparison is the bearing housing area for the TCS is larger to accommodate the larger bearing and the rear brakes from the GT6. The "ears" for the four mounting bolts are beefier on the TCS. There may be others that I've missed, maybe someone else can add more.
 
I don't have a hub from a TC for comparison but there is a picture of the TC hub carrier on the RD Ent website. From what I can tell, the TC hub appears to have features of both the S2 and TCS hubs. The TC hub has the LEFT/RIGHT letters embossed on the casting like the S2 but has a single hole for the shock mount and lower link as per the TCS. The bearing housing area looks closer to the S2 than the TCS. Please be free to add more differences that I may have missed.   

 

[EuropaTC]

Good shots there Joji and looking closely at them I'd guess that my TC carriers have more in common with the S2 than the TCS, which looks a much better design/casting. 

The TC only has one hole for the bottom link/damper fixing as per the TCS but otherwise I'd be tempted to say it's the same casting as the S2. They do have the Left/Right cast into the sides and the 4 tapped holes on each side for mounting the trailing arm look less substantial than your TCS version.

[46lotus]

Joji, The cast left and right are not a good indicator as I have both S1 and TC cars and neither have left or right cast into them.  I also believe the TCS housing has a different bolt circle as a TCS housing will not fit a non TCS trailing arm. This may also apply to TC housings. I have a damaged trailing arm where someone tried to redrill the arm to fit both applications, it has 6 holes per side. 
Tom

[EuropaTC]

Interesting point on the bolt circle Tom, I wonder how that came about ? 

I thought the S2 & TC used the same brake backplates and looking at my parts list the same backplates are listed for the TC & TCS. (and look similar number styles to the S2)  So I'd drifted into the concept that "they'll all be the same".

But after reading your post and looking again at Joji's photos, unless it's the angle of the shot there does seem to be a larger bolt circle on the TCS carrier. (picture 5). 

I guess it makes sense, again checking the parts list the TC & TCS do have different numbers for the trailing arms. Did the change come about with the move to larger rear brake shoes & larger inner bearing ?

[Certified Lotus]

Great write up. I have two sets of 72 TC hub carriers and they are both the same. See photos below of one complete set.

[Grumblebuns]

My observations were not meant to be definitive due to the small samples I had on hand. I don't know how to explain the lack of LEFT/RIGHT letters on Tom's TC hubs. Could they be the result of a PO modification to TCS hubs?  Both Brian's and Glen's comments seem to support the TC hubs having the letters embossed in the casting however.

One other oddity I notice with the S2 hubs were the non symmetry of the mounting holes. The spacing between the upper holes vs the lower holes are different. I documented the dimensions on the attached photos. The TCS hubs appear to be symmetrical.

As Tom stated with his S1 hubs not having the letters, I did a quick check of my S1 and it also does not have the LEFT/RIGHT letters.

Perhaps someone could take a quick peek under the skirts of the TC Europas at the next LOG and record what they find out.

[Certified Lotus]

If you look closely my hub carrier looks entirely different on the inside where the bearing goes. It is stepped and has more of a hollow area after the flange. Why such a difference?

[Roger]

Well my TC certainly has Left/Right markings.
Certified, yours look like mine. There is a step inside the outer flange to positvely locate the outer bearing. The inner bearing is not positively located.

[Grumblebuns]

Glen, can I ask you a favor and measure the distance between the bolt holes of your TC hubs both the inboard and outboard side. I tried to fit my TCS hub to a trailing arm and found out that there is a slight mismatch between the holes of hub and the trailing arm. As the pictures shows, on the inboard side, the fit is very close but not perfect. The outboard side is off by quite a bit.

I'm starting to wonder if the bolt holes between the TCS and the TCs are also different and that I have a TC trailing arm.

Joji Tokumoto

[Certified Lotus]

JoJi, here are the photo's you wanted.  I did two measurements, one from center and one outer edge to outer edge of the holes. Hope this helps.

[Grumblebuns]

I re-measured my S2 hubs using the outer edge of the holes instead of the center and got almost the same values as what you measured. They are close enough that I would say that the S2 and the TC hubs probably have the same hole spacing

To add the TC hub to the visual differences between the Europa hubs, this is what I've picked up on the TC hub.
- mounting bolt spacing is the same as the S2 hub, spacing is non-symmetrical.
- single bolt hole for lower shock mount and lower link as with the TCS
- has RIGHT/LEFT embossed on the hubs as with the S2
- inboard bearing area has an additional step in the bore as shown in Certified Lotus photo

With the small number of hub examples that I've come across, there may exceptions to what I've posted but it should be true in general. I came across one other possible difference between the S2 and TCS hubs. Both hubs have drain holes on the bottom. On the TCS the holes are offset to one side. The S2 hole is almost but not quite centered in the middle. The picture shows the obvious difference

[Roger]

TCS doesnt have Left/Right embossed.

[Grumblebuns]

TCS doesnt have Left/Right embossed.

Yep, had a mind fart, corrected the error, thanks.