Rear suspension parts and questions

[Lotus7]

Does anyone know if there are any differences in length in outboard stub axles for the TCS and the earlier cars? I've heard that the TCS uses a different inboard bearing. But I don't know if the length of the stub axle is the same as the earlier cars. The overall length on the stub axles for my S2 measure about 8.5"

Additionally, from what I have found, it appears that the half shafts are shorter by about 0.5" compared to the S1/S2 cars (not sure on the non-special TC cars). My S2 shafts measure about 15 7/8" and I have been told that the TCS shaft is 15 3/8" (both measure center of u-joint to center of u-joint). Can anyone confirm this?

I also think the TCS cars may have used 1310 universal joints. Can anyone confirm that?

The reason for asking is that I'm looking into having some new outboard stub axles made. From my calculations, the new axle, using a 1310 splined u-joint yoke will require the half shafts to be shortened by 0.5" - same length as the TCS half shafts.

Hopefully, someone can cast a little light on this.

Lee
Europa S2Zetec 0712 type 54

[EuropaTC]

Hi Lee,

I can't answer all your questions with certainty, but I'll make a start and hopefully someone else will come along with more info later on.

1. Outboard stub axles. I believe the TC and TCS use the same outboard axle and hub carrier casting.  I checked with my Parts List and it gives the same number for the axle on the TC and TC Specials (UK & Federal).   At one point I did ask one of our UK Specialists about converting my TC to the later Special bearings & brakes, mainly because I seemed to get through a lot of rear wheel bearings at the time and thought the larger bearings would be better.   He told me that Lotus just used 2 of the larger bearings in the housing instead of one large, one small as on the TC.  To accommodate this, all they did was machine a bit more off the castings but otherwise they were the same.  Again that ties in with using the same stub axle as the extra bearing width would be "inside" the carrier and landing area on the shaft would just be machined a bit wider.

Following on from that logic, the early S2's used an oddball smaller bearing with the same OD but different ID (31mm ?) to that of later cars. This became difficult to source over here (read more expensive  )  and I seem to recall one common mod was to machine the stub axle to take the 30mm ID bearing of later cars.  Which would align it with my TC as far as bearings & brakes are concerned, so my thoughts would be that the S2 also uses the same part number stub axle as the TC. If anyone has an S2 parts list, the TC & TCS part number is A074 D6005Z for the stub axles. The inboard (central) shaft is A074 6004Z if you can cross reference lists. 

2. U/Js. I don't understand what you mean by 1310, but I can tell you that again the parts list gives the same part number for the UJ on both the TC & TCS, UK and Federal versions. I'm pretty sure it's just a standard UJ as fitted to Fords, Triumphs, etc,  of the period, the only difference I saw when buying the last lot was that some came with a grease nipple and others were sealed for life.

3. Measurements. I don't have any to hand so all I can add is that again the Parts List gives the same part number for the inboard (centre) driveshaft for all the TC variants. If no-one comes along with details I can measure the ones on my TC later on for you.

Can I ask why you're having new stub axles manufactured ? If the problem is that your old ones are scored on the bearing surfaces, would metal spraying and machining bring back the correct dimensions ? It's not something I've had to do but it's quite a common practice on pump shafts, etc, and so is relatively cheap to do. Certainly easier than making a new stub axle from a lump of metal !

Brian

[Roger]

Brian,
The TC and TCS have different Wheel Bearing Housings with different part numbers. Check your parts list again! And, of course, the radius arms, hubs and brakes etc. are different.

The TC housings have "Left" and "Right" cast in them, but the TCS don't, I think. I believe the castings were changed, not just bored differently.

The stub axles are the same though.

[EuropaTC]

Hi Roger,

Ah, it bears further investigation then, anyone got one of each on the bench to measure  ?

I know the part numbers are different in the book but I'd just assumed that would be down to the different bearing seats/machining, and that was why I hadn't attributed any great significance to it.   It goes to show that making assumptions around these things isn't always a good idea. 

Sorry for the duff information Lee, I had thought the logic followed through.

[Lotus7]

Brain,

No problem with the logic thing, it we were good a logic would would not be playing with 40+ year old cars!

You also asked why I'm interested in replacing the stub axles. The Europa stubs were reused from the Hillman Imp where they were designed to work with something like a 36hp engine. My car has a Zetec for power, and will be used for road, track days and autocross. So I'm a little worried about breaking one of those Hillman Imp axles!

Here is a photo of what I would like to replace the Imp parts with:

[cal44]

According to R.D Enterprises there is a difference.  He has some for sale and lists them as the TC is not for the TCS.  That all I got.

[EuropaTC]

The Europa stubs were reused from the Hillman Imp where they were designed to work with something like a 36hp engine.

   That's Colin Chapman for you Lee !  I didn't realise they were sourced from the Imp, but that fits well with his use of the Imp donuts in the early Elans, perhaps he used to drive one to get him to work at Lotus back in the day ? But thanks, that's another little fact to note down, just in case.....

Moving on - I guess the picture you posted is a commercially available axle, is that so ?  I'm never one to stop guys spending money on their toys, but before you go that route it might be worth asking one or two of the racers on the forum what they're using and what the reliability is like for standard stub axles. If they have changed them, then you'll probably get the dimensions they used as well, because both Ben & Mecky are in S2s.

Brian

(Mike - yes, I know the TC & TCS carriers are different part numbers, it was the fact they produced a new (thicker ?) casting for what was going to to be the last couple of years of production that's thrown me.   I remember looking at my carrier and thinking "yes, that'll machine out, but is it worth it ?"  In the end after talking to my local Lotus guru about reliability with the larger bearing, I decided not)

[Lotus7]

More likely one of the employees had parked his Imp in the parking lot and Colin 'borrowed' some parts off the car   
The axle pictured was designed by a Europa own who had a few sets built and no more are planned. They were designed (if I understand their history) for the TCS and thus what appears to be a large 1310 series u-joint yoke on the end of the axle. My understanding is that these fit with no modification to the rest of the suspension.

I put a piece of wood into my metal lathe and made a similar axle to experiment. I purchased the smallest/shortest yoke I could find - a Dana 35 pinion yoke. With my home made axle, everything fits together but due to the size of the yoke, the half-shafts would need to be shortened about 0.5".

I have my version of the Banks Twin Link suspension and there appears to be very little clearance between the yoke and the suspension bolt.

The reason for my quest is to solve two known problems with the Europa stub axles. First, they tend to break at the end of the splines, just where the threads start. Not a good feeling as the wheel tries to leave the car. Second, the splines on the outer hub tend to wear a lot and people ofter have problems with the retaining nut getting loose. Perhaps the search to get the 150 lb/ft or torque to keep things tight contribute to the broken axles.

The stub axle design above, solves all of those problems - if I could just find a nice, short, 1300 (not 1310) yoke it would be an easy fix!

Lee
Europa S2Zetec 0712 type 54

[benbeames]

I have heard many horror stories about the stub axles.  Recently I had one of my nuts (driver side) come a little loose (D-washer still held it in place though).  Since I was pulling my transmission anyways and the car would be on jacks stands for a couple days I went ahead and pulled my hubs off.  To make a long story short, I don't have any useful information to give because I think the set-up on my car has been changed by the previous owner. 

It still looks like the stock setup, using the stock bearing casing and hubs (can't tell you on the bearing sizes though because I didn't investigate that far), but my U-joints look different from the pictures of other's U-joints I've seen on the internet and though my hubs were a little warn, the splines of the stub axle looked brand new.  I've put about 7,000 miles on my car in the past 3 years and the odometer has 68,000 miles on it.  So there's no way these are the original stub axles (also I can tell one of my bearing housings has been replaced just from its color).  Based on what others have said about how often they have to service theirs, it seems unlikely to me that my splines would look THAT good even if they had been replaced shortly before I bought it, though that may simply be the case.

So all I can tell from my car is it hasn't gotten enough wear and tear on its stub axles to have any problems in the time I've owned the car, OR its had some stronger parts installed at some point.  And since I don't know what the case is, I can't really say what's been working for me.

[EuropaTC]

Based on what others have said about how often they have to service theirs, it seems unlikely to me that my splines would look THAT good even if they had been replaced shortly before I bought it, though that may simply be the case.

So all I can tell from my car is it hasn't gotten enough wear and tear on its stub axles to have any problems in the time I've owned the car, OR its had some stronger parts installed at some point.  And since I don't know what the case is, I can't really say what's been working for me.

They might be the original parts Ben. My car has the original ones and the last time I looked the splines were in great condition.  I'm pretty sure they're OEM because I've never changed them and the original owner was the sort of guy who wrote down everything he did with the car (it came with one notebook that detailed petrol, oil & mileages for example) and I don't think he changed them. My problems have always been around slight play in the UJs and wheel bearings and then a picky MoT guy would fail it for having worn bearings. You don't need much wear on all those joints with it working as an upper suspension link and I used to use it as a daily driver. Now it's a dry weather toy it doesn't have the same problem.

When I got the car my local Lotus guy told me about the hub nut problem and I think there was a bulletin about it. The advice was to reassemble the hubs on the splines using Loctite so that it completely filled the gaps. The hub nut was also loctited in place (as well as the washer) to keep it all tight. Apparently a "feature" of the cars 

Lee - I'd be interested in seeing your twin link suspension, any chance of a photo or a new thread about it ?  I'm not about to rush out and change mine but I did think about a 5sp box at some point, which would mean having to do something about the suspension loads as well.

Brian

[Lotus7]

Guys,

Here is a snap of one of the original stub axle from my S1 (67k miles).

As you can see, it looks pretty good except for the first 20mm or so out from the 6206 bearing. That wear seems to have been caused from the spacer that fits there. As normal as the splines look, the hub actually rocks in and out, so I know there must be some wear.

I'm guessing that the biggest killer for the splines is a axle nut becoming a little loose. Perhaps they are suddenly a little loose because the metal on the stub axle is starting to stretch?

Just looking at this photo, I'm starting to think that all that is needed is a new stub made from properly hardened 4340 steel. Perhaps furnish the old stub axles, have them remove the yoke and weld it to the new stub axle. And the new axle would have threads the same size as the axle shaft (30mm) or just a little smaller.

I'll post some photos of the Twin Link later today.

Lee

[cal44]

Please increase my learning curve.  Are the stub axles from Europas from the Imps?  Since Imps can be quite successful in racing, the boys must be using very strong  axles, stock or aftermarket?............right?

Please correct me if I am not getting this.

Mike

P.S. I am a Sunbeam fan.  Here in the States Alpines can be bought for a song.  Don't see many Imps.

[Lotus7]

Yep, from Imp's. I think there maybe a stronger version of the stub axle available from Imp Works, but I've not been down that road.

Lee

[EuropaTC]

Hi again,

Well, you can't argue with that picture, it looks very worn. Mine are nothing like and must have at least the same sort of mileage on them. My hubs are a loose sliding fit on the splines so I think that's normal production tolerances, I don't think the splines are worn because you can still see machining marks present on mine. (or could the last time I did the job, but admittedly I can't check the bores of the hubs themselves for wear)

I agree that the wear looks to come from the spacer, but in order to wear surely there must be movement ?  Following logic (dangerous, as proven above  ) I'm thinking that it can only happen when the compression on the whole arrangement reduces either by the hub nut loosening, the inner bearing spacer compressing, wear in either the bearings or UJs, the sub axle stretching under tension as you say, or finally the gearbox output shaft yoke not being shimmed correctly. 

Personally I'd rule out either steel compressing or stretching under tension because you'd need much higher loads than you'd get from cornering and my thoughts go to either incorrect assembly or cumulative wear in the bearings/ujs in the upper link. It always surprised me that checking the end-float on the rear wheels/transaxle output was supposed to be done at the 5k & 10k services, and I'd be willing to bet that once the cars passed to second owners or DIY servicing, that job didn't happen.

So lots of places for potential wear & subsequent movement and my guess would be that's what leads to wear by that collar, and the subsequently fatigue failures on the threads at the end of the stub axle.

I can see a failure at the threads due to sideways loading/fatigue but not to power transmission because if the splines are doing their job, 99% of the loading will go through the stub axle splines which are before the thread failure points ? (a question for debate, not a definitive statement  )

The more I think about this problem the more I come round to thinking it's not the stub axles at fault, it's the maintenance or if you like the potential failure mechanisms due to the OEM design. Perhaps your twin link suspension is a way around this issue on well used cars ? I'm so intrigued now that I think I'll post a separate thread about the topic, please chip in with pictures !

brian

[Steve]

Conventional wisdom is that the original spacers were mild steel. Over time, they fret *, which increases the clearance, which leads to MORE fretting wear, & increased clearances in the bearing stack-up. The fix is to replace any soft axle bearing spacers with hardened steel ones, machined to correct tolerances. If you have access to the spacers, carefully measure them & ensure they are to spec. Secondly, drag a common file across the side of one (NOT the bearing surface) and if the file "bites" at all, you have a metallurgically "soft" spacer. It may be within spec, but subject to wear over time. On my car, one upright had a soft spacer, one did not.  The dimensions of the spacer are in the shop manual.


 * http://en.wikipedia.org/wiki/Fretting