Inner fulcrum bearing tubes - new discovery

E-Type
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In another thread I talked about how my inner fulcrum bearing tubes are shot. This seems to be pretty common. Research indicates these should be hardened, yet I don’t believe any of the aftermarket offerings are - I’ve called two of the usuals so far, and will call some others tomorrow. I’ve also seen some aftermarket ones listed that show a length of 1.125", which I believe could be too short (I haven’t fully investigated that yet).

The dimensions of the bearing tube OD and ID seem to be common, but the length is more unique. Mine measure (0.875" or 7/8") OD, (0.625" or 5/8") ID, and 1.145" long, which I believe are the correct/OEM dimensions for my series.

Assuming my usuals-hunt turns up dry tomorrow, I’m considering ordering these press-fit drill bushings from McMaster-Carr and having them shortened to the proper length by a local machine shop. The OD and ID dimensions are good, and they’re hardened to Rockwell C61. I called McMaster-Carr and these are made from C1144 steel. I’m no machinist/metallurgist though - does anyone see fault with this approach?

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Hi Rob,
The length of the bearing sleeves is quite important, as the full length of bearing sleeves and long spacer between them is to lock up solid longitudinally when the nuts of the inner shaft are tightened and without excessive end float of the wish bone. This is to ensure that the bearing sleeve stays put and the drawn cup needle roller bearings rotates with the wishbone. What you don’t want is the sleeve able to rotate with the bearing and therefore, the actual bearing becomes the ID of the sleeve and the inner shaft.

When purchasing the drawn cup, needle roller bearings, there will be a corresponding, various lengths, inner bearing sleeves available. I’m unaware of an off the shelf sleeve of the correct length for your purpose available from bearing suppliers. Accordingly, we purchase the units that are the closest over length and machine them to the correct length.

These sleeves have to be hard as there are needle rollers running on them. The sleeves available that correspond to the drawn cup, needle roller bearing are correct for the application, in terms of hardness and OD dimension and can be turned to length using carbide inserts.

Brent

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Thanks Brent. I was originally unaware that the length was critical until I did some reading in the archives. I appreciate you reinforcing that information!

What you’re saying totally makes sense - purchase the proper dimension/material sleeve along with the bearing itself, and trim the sleeve to proper length. I have not had any luck searching for a “matched set” online. Maybe I just need to call one of these bearing suppliers and have a conversation on the phone.

RobY

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I’ve been using bronze bushings for the last 25 years. They seem to be bulletproof.

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Are these the bronze bushings originally supplied by GTJ or do you have a different source? Would you be able to provide a simple sketch showing how they are fitted?

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Hi Geoff I’ve had a number of sets over the years. I recall one came from XK’s Unlimited, and I’ve had sets made. Let me get back to you on this - I’ll search throu my stuff.

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Hi Terry,
But in the case of using a bronze bushing, its the whole bearing that will be bronze and not a drawn cup needle roller bearing running on a bronze bush.

Whole kits, including bronze bearings for the Hub Carrier fulcrum bearings, are available and are popular in race car applications, but I don’t see them as being a better alternative to the taper roller bearings for the Hub Carrier fulcrum.

Brent

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Hi Geoff I thought I might have some bronze brgs to show you but I don’t have any that are not on the car. I’ve made a sketch of the simplest one to use. It is no more than a brass reproduction of the stock bearing set up, instead of having the two roller bearings it’s entirely of brass. The benefit if this setup is that you use all the other components, by that I mean the rubber ring and associated parts to seal the bearing and as well the large washers that go between the bearing and the cage etc. From experience you do need to seal the bearing, or more properly the rotating washers on each side of it.The measurements are made with what I believe is an accurate caliper. The bearing can be just a finger push tight fit on the inner fulcrum hole. Ignore the brass ring with the o ring, thant’s an alternative version but we don’t need to go there

Are you in Calgary? There are some guys there currently trying to set up a Jaguar club and they have a Jaguar show set up for June 19th, PM me if you want more details. terrysturgeon@telus.net

IMG_9053 (1) IMG_9055 (2) ![image|640x480]
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Hi Brent
I’m not an engineer or prof mechanic or really anything significant in car maintenance - but
I’ve been working on my own E Types since the early 70’s. From the first moment I looked inside the hub and the inner fulcrum I’ve thought this wasn’t a great solution. Usually it was rusted, even though there was some grease, and the rust was between the rollers and also on the outer ring (cup?). Then I’ve seen situations where the rollers had worn longitudinal grooves in the cups on the outer fulcrum. and on the inner bearing in the inner fulcrum. I didn’t consider anyone I saw as being reusable, which is a problem as they are not currently available and haven’t been for a while I believe. I started using alternative bearings in the early 90’s on the various cars I’ve owned including two that I raced, and this continues to day in my '68. I tried bronze bushings in the outer fulcrum bearings but had a problem with one cracking the aluminum hub. now I use ones made out of nylon. They’ve been on the car for 10 years plus with zero issues and zero wear. They have to be shimmed of course.

I remain perplexed why you would use needle roller bearing in something that has very small rotation, very slow rotation, and carries a significant load. The actual surface area of the bearing is very small.

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Where I work we restore all types of Jaguars, but mainly E Types. With all things mechanical, where alternatives are concerned, we give our clients options. Some aren’t up to making the decision based on mechanical engineering knowledge. I don’t believe I made any reference to having a preference one way or the other regarding the type of bearing to use in the two fulcrum areas of the rear suspension; we have used both roller bearings and solid material type; I simply answered Rob’s question. With regards to what is used at the end of the day is up to our clients.

I’m quite aware of the issues using needle roller bearings in an application of minuscule rotary motion, but solid bearings in the outer fulcrum has its own set of issues. Even with the outer solid bearings set up with end float, rather than the desired pre-load, the bearing ultimately becomes the relatively small diameter shaft running in the corresponding bore of the solid bearing; the larger OD having more resistance.

In our works there are two qualified mech engineers; we don’t do things without due consideration. Regarding the shortfalls of the needle roller bearings and hardened bushes, it takes quite some time for the brinelling to occur.

Brent

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Terry,
Is it a specific type of brass? Perhaps sintered bronze? I could make make those myself.
Rob in Fredericton, NB.

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I use ones made out of nylon. They’ve been on the car for 10 years plus with zero issues and zero wear. They have to be shimmed of course

I’ve not run across the mention of nylon bearings before. Where were those sourced?
.

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Thanks for the pictures. That looks like a sensible alternative where the brass bushings and the fulcrum tubes are the wear surfaces sparing the fulcrum shaft. PM sent.

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Terry, assuming I’m understanding how the bronze setup in your diagram is intended to work, the overall dimension of 1.42” seems too long to me. Possible typo?

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Good eyes. I dropped the 1 when I transposed the number from the garage drawing to the redrawn one that I sent. I measured it at 1.142

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I’ve changed the photo to show the correct dimension.

“Is it a specific type of brass? Perhaps sintered bronze? I could make make those myself.”

I would have liked to make them from oilite but my machinist couldn’t find any.

“I’ve not run across the mention of nylon bearings before. Where were those sourced?”

I don’t remember - I’ve had them for years. There was a lot of this stuff made years ago, but not so much these days. You could easily have them made. I could work out rough dimensions if you’d like.

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Hi Brent Some sloppy language in my post. When I said you I wasn’t meaning you personally, it was in reference to the engineer who designed the system.

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Hi Terry,
We’ve used a similar system to that described by your sketch, but there is an issue with it, if the car is used as a frequent driver, in all weather…

When lapping a part, you have a Lap and the Part to be lapped. The lap should be softer than the component being lapped, the reason being is that the abrasive being used should embed in the softer lap material wear away (lap) the harder component being lapped. We’ve made many aluminium alloy parts for the aircraft industry and its taboo to use any type of abrasive paper to deburr sharp edges that can’t be deburred in the machining cycle of the machine. The reason? There can’t be any possibility of abrasive embedding in the part and have the potential of wearing a mating part after assembly.

The design of the part in your drawing creates bearing surfaces of the ID of the Inner Fulcrum bore and the OD of the bronze bearing. As you have pointed out in an earlier Post, having identified rust in the needle roller system, the sealing system is not infallible. Accordingly, there exists the real possibility of moisture and dirt getting past the seals and despite the close fit of the bronze bearing and the bore of the wishbone, ultimately embedding in the first few mm of the OD of the bronze bearing and wearing the bore of the wishbone.

Our modification to your part is a thin walled steel bush pressed into the bore of the wishbone and the bronze bearing machined to be a firm sliding fit in the bore of the bush. The steel bush is a sacrificial part in the even that abrasive material gets past the seal.

Brent

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I’m sure there is a better way to do this, as you suggest, but as I say I used this type of bushing for 20 plus years without issue, or wear to the bushing. Water has never been an issue. The seals are to keep small stones and other grit from collecting between the washers. They really chew those up if you don’t keep them out. Here’s a photo of brass washers that I started with without seals. These were purchased from a supplier who I can’t recall. Since using seals I’ve had zero issues.

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For the other enginerd-types on JL!! If you can suffer through my thought process and math, I’ve got questions at the bottom!

Jeez, I can’t believe it’s been 8 months since I started this thread! Since then, I was able to locate and purchase some inner fulcrum bearing tubes that are the proper material and proper dimensions, except for the length. They are 1.385" long, so I’ll need to have them trimmed down by a local machine shop.

Samples of old and new inner fulcrum bearing tubes:

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In preparation for having them cut, I was taking some measurements yesterday (measure twice, cut once) to ensure I will have them cut to the proper length. As I mentioned above, the OEM ones I removed were 1.145" long. That “OEM” length was supported by @angelw (Bill Angel) in post #16 on this UK E-type Forum thread on a similar topic:

https://forum.etypeuk.com/viewtopic.php?f=3&t=7711&hilit=inner+fulcrum+bearing+length

Anyway, while taking measurements I discovered that the width of my inner fulcrum arm flanges are not all equal. I was not expecting that. The two pictures below show the dimension I’m referring to, and the variances in the widths across the four flanges. “Opposing corners” are very close to measuring the same, which I find interesting, and I’m wondering if there could have been a variance in the original casting mold?

6b61b2add48abfe3e4620d837ab0bfa6f08aea68
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So, what’s the big deal? These dimensions, along with the inner fulcrum bearing tube lengths and inner thrust washer thicknesses are critical to ensuring the inner fulcrum bearing tubes are captured by the outer thrust washers and keep the bearing tubes from spinning (as discussed earlier). In the UK Forum thread I linked above, Bill calculated a 0.006" clearance between the inner and outer thrust washers, with a 1.145" long inner fulcrum bearing tube (meaning the tube is 0.006" longer than the sandwiched components and the tube is captured).

With my fulcrum arm flange widths varying by ~0.025" in width, that’s a huge relative difference when we’re talking ~0.006" clearances!

I took some measurements of my existing inner fulcrum hardware, and the new rubber sealing rings I purchased:

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Calculating worst cases for my thick and thin flanges and inner thrust washers, with a 1.145" bearing tube:

Bearing tube length - (inner thrust + fulcrum flange + inner thrust) = clearance

Thick worst case: 1.145" - (0.118" + 0.897" + 0.118") = 0.012" clearance (tube is captured)

Thin worst case: 1.145" - (0.117" + 0.871" + 0.117") = 0.040" clearance (tube is captured)

So, while the tubes are captured with a 1.145" bearing tube, I was concerned that the resulting clearance may be too much and not actually compress the sealing ring at all, leaving the bearing assembly “open” for debris intrusion. If I did my math correctly:

[Bearing tube length - (sealing ring + fulcrum flange + sealing ring)] \ 2 = compression for each sealing ring

Thick worst case: [1.145" - (0.139" + 0.897" + 0.139")] / 2 = - 0.015" (each sealing ring compressed ~10.8%; seems reasonable)

Thin worst case: [1.145" - (0.139" + 0.871" + 0.139")] / 2 = - 0.002" (each sealing ring compressed ~1.4%; seems rather low)

Out of curiosity I calculated worst cases for my thick and thin flanges and inner thrust washers, with a 1.125" bearing tube offered by the usuals:

Bearing tube length - (inner thrust + fulcrum flange + inner thrust) = clearance

Thick worst case: 1.125" - (0.118" + 0.897" + 0.118") = - 0.008" clearance (tube is NOT captured)

Thin worst case: 1.125" - (0.117" + 0.871" + 0.117") = 0.020" clearance (tube is captured)

I’m wondering if the usuals maybe had some flanges that were on the thinner side when they decided to offer 1.125" long bearing tubes?

All of this makes me wonder if the variance in inner fulcrum flange thicknesses is common or not. Has anyone else measured?
Anyone have some on the bench they can measure (@BrentKeats perhaps)?
Do I have anomalous fulcrum arms?

I’ve got to verify my math and since I’m having then inner fulcrum bearings custom cut, figure out what length I want to use. I’ve thought about having them all cut to the same length and maybe adding some thin shims to balance things out if I need to, but I haven’t decided yet.

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