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Belt idler pulley and bearings.  Rate Topic 
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 Posted: 11-12-2016 09:03 pm
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Esprit2
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And another view...

Attachment: Timing Belt - Pulleys and Tensioner - Parts Dwg EF - 97kb.jpg (Downloaded 133 times)

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 Posted: 11-12-2016 09:13 pm
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On a related subject. The auxiliary pulley abutts against a little wire circlip that is not very strong. The pulley can get loose even when the bolt is properly torqued. Apply a little blue/ medium strength Loctite in the pulley bore prior to installation, but try to keep it out of the keyway.

If the pulleys were properly installed last time, heat and a puller will be required to remove the aux pulley. Just be careful not to direct the heat toward the lip seal directly behind the pulley. I wrap a wet rag around the shank of the shaft to protect the seal, then direct the torch flame back to front.

In contrast, apply Anti-Seize to the cam pulleys. They butt-up against a large shoulder and get clamped tightly. They're not going anywhere.

Regards,
Tim Engel

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 Posted: 11-13-2016 04:46 am
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qwerty
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Thanks Tim, That's most of the info i needed. I will measure the stock J-H spigot/male boss that pushes into the block and compare with your measurements. If the spigot/male boss matches then Geoff Kemp's Kit (or a Lotus Hub and one piece bearing/roller) may be a direct replacement for the J-H and in my opinion a much better design. The only extra piece we'll be buying in the kit is the stud (stainless apparently), this may still be needed if there are any offset differences though i doubt it. If you would reply with my measurement question below i'll be the guinea pig and try Geoff's kit to check the offsets and confirm it is a direct replacement. If all is well then the intial outlay will be a new Lotus hub and bearing but after that only the bearing will be needed for matainence when changing the belt.
*Snip "The two major differences are 1) the purpose-made tensioner bearing/ roller, and 2) moving the adjuster hex to the front side, where it's easily accessible. The eccentric hub is a press-fit into the bearing's bore."
The third major difference 3) The bearing's bore: the ID on the 6005 bearings is 25mm whereas the ID on the SKF 414871A is 31mm. This is why i'm after Geoff's Lotus replacement. Our current J-H 2 piece hub (in your pic above part 14 and 15 are two separate pieces and part 14, the adjuster nut, is sloppy as hell in the bore of the 6005's) will need to be swapped out for the Lotus hub to make use of the purpose-made tensioner bearing/ roller (SKF 414871A). The press fit surface of the hub will be larger on the Lotus version than the J-H Version to accept the SKF 414871A - It should measure somewhere just under 31mm. Would you please confirm with your lotus hub you had in your hands?

I hunted high and low for a replacement hub only yesterday to no avail, I messaged Geoff through ebay as currently shipping is not available to Aus so hopefully he will respond soon so i can get this shipped before the belt learns the tracking.

Good info on the Aux pulley, i'll check on it.

Last edited on 11-13-2016 05:46 am by qwerty

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 Posted: 11-13-2016 06:55 am
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qwerty wrote:
The third major difference 3) The bearing's bore: the ID on the 6005 bearings is 25mm whereas the ID on the SKF 414871A is 31mm. This is why i'm after Geoff's Lotus replacement.If the J-H and Lotus tensioners are functionally interchangeable (and I think they will be), then it would only be as complete assemblies. Don't expect any of the bits to interchange individually, other than the stud, washer & nut.
qwerty wrote:
The press fit surface of the hub will be larger on the Lotus version than the J-H Version to accept the SKF 414871A - It should measure somewhere just under 31mm. Would you please confirm with your lotus hub you had in your hands?

I hunted high and low for a replacement hub only yesterday to no avail, I messaged Geoff through ebay as currently shipping is not available to Aus so hopefully he will respond soon so i can get this shipped before the belt learns the tracking.
Have you tried SJ Sportscars, PNM Engineering, or Southwest Lotus Centre in the UK? Also, JAE or Dave Bean Engineering in California, USA?

Actually, your best bet might be a used eccentric from Lotusbits in the UK. If need be, Mike Taylor could also provide an inexpensive used front seal housing to match the tensioner. http://lotusbits.com/

I have the 'complete' tensioner here... ie, the eccentric pressed into the bearing. Unfortunately, that means I can't access the diameter you want measured. I do intend to take it apart to install a new bearing soon, but I don't have a hydraulic press of my own to do it now. Every Tuesday night is 'Toybox Night' (my buddy's shop), and he has a press. My plan was to do it then... this coming Tuesday. Is that good enough?

In the meantime, I can confirm that the hub is a press fit into the bearing's bore. The replacement bearing is a Flennor S03299 (I've also seen FS03299 referenced), and it measures...
1.214" (30.8356 mm) ID Bore <<<<<<<< ie, a slight negative fit with that.
2.478" (62.9412 mm) OD
1.179" (29.9466 mm) Wide

BTW, the bearing that is on this hub now is one of those inexpensive Chinese bearings I cautioned against using. No brand markings, but this one had black seals, not the blue ones I mentioned. A friend bought it for his Esprit Turbo, and it only lasted a few weeks. I popped the seals out, and it appears the manufacturer was very stingy with the grease. Like, almost none.

Regards,
Tim Engel

Last edited on 11-13-2016 07:01 am by Esprit2

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 Posted: 11-13-2016 09:33 am
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My thoughts also Tim only you combined it all in to one sentence... Well put! -  "If the J-H and Lotus tensioners are functionally interchangeable (and I think they will be), then it would only be as complete assemblies. Don't expect any of the bits to interchange individually, other than the stud, washer & nut."

Happy to wait till Tuesday, for the dimension, It doesn't have to be exact as it'll either be closer to 25 or 31mm and we'll have our answer. I've already ordered a SKF 414871A...

Also Blue Seals usssuallllly refer to a stainless bearing. Not always though.

I agree, bearings ain't bearings, most shops will tell you it doesn't matter where it's made as the big name brands have plants all over the world (which is true) but where they source their steel from, how they treat the steel and the quality of the plant and training most likely makes a difference.

Bearing choice is a bigger factor and choosing the wrong bearing for it's application can give it a bad name. Choose for the application, Let the bearing guy know where it's going to be used and he'll hopefully make a few educated suggestions considering for example, abutment, number of balls, type of cage and seals, load including vectors, tolerance "ABEC" rating and clearance "C" Rating, RPM Rating, ambient conditions heat/corrosion as well as extremes. They have BIG bearing encyclopaedias that they can address. Heat is a big killer to the lubrication and seals, and that bearing you pried the seal from may have just had it's grease boil off or may have been made to suit high rev 20,000rpm in which case it would have been filled with oil rather than grease or as you said just plain old inexpensive non branded poor quality.

If you simply ask for a 6005 bearing the shop guy will most likely just give you what he has on the shelf yet there will be a mountain of choices based on the variables above and probably more. I am no bearing guy, i just put the application forward and asked the questions to a good bearing shop, they had 11 dollar NSK 6005's on the shelf and was about to walk away with them when a knowledgeable sales person overheard the conversation and that's how i came across those Beco's. The SKF 414871A being specifically designed for the tensioner purpose will have had all these considerations implemented into it's design so we don't need to do the research and that's why i think exploring this whole interchangeability experiment will be well worth it. Sorry for the novel, Tim may just stroll in and boil this down to one sentence haha

I have tried some of those shops and will keep the hunt on for the Lotus hub tonight with your suggestions.

Cheers, Pete

Last edited on 11-13-2016 10:27 am by qwerty

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 Posted: 11-22-2016 10:32 am
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Update

This is a no go, the spigot diameter is fine but it is too is too long for the J-H front housing. Additionally once we faced the spigot down to size on a lathe so it would fit, the bearing sits too far inward so the belt will be running off the front edge, not by much ~3mm yet enough to cause a bit of worry.

I will be exploring this in the future to make another part suitable for a replacement for the J-H.

Last edited on 11-22-2016 10:33 am by qwerty

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 Posted: 11-22-2016 03:25 pm
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If I understand you correctly, what you need is a version of the Lotus eccentric hub with more shoulder and less spigot... correct?

How about making a spacer ring to fit between the boss on the JH seal housing and the shoulder on the eccentric hub? Well... you've already shortened the hub's spigot? Then two spacers. One to put the spigot length back, and one to fill the gap between the seal housing and the hub's shoulder. I know, I know... that's starting to sound like a kluged up stack of parts; but it would work as a mock-up to evaluate the configuration.

You probably didn't intend to start a J-H upgrade parts business, but making a JH-specific version of the Lotus eccentric would be a good thing. IMHO, the purpose-built 'tensioner roller/ double-row bearing' is a better solution than the JH assembly of loose parts; and putting the adjuster hex on the front side is a great convenience.

Sorry if I led you down the primrose path on that one. The cylinder block and the eccentric hub are compatible in terms of the plane of the timing belt. It's the boss on the J-H front seal housing with which I have no dimensions or experience.

Keep us posted on where you go with this.

Regards,
Tim Engel

PS... for those of you in the USA, Happy Thanksgiving.

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 Posted: 11-22-2016 05:23 pm
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If I understand you correctly, what you need is a version of the Lotus eccentric hub with more shoulder and less spigot... correct?
Correct. I thought about a spacer but given the thing has to stay in place i opted out of the spacer just more parts to come loose besides as you noted it would turn into a cheeseburger of parts...

I'll keep you posted, my mind has been keeping me awake tonight going over dimensions in my head. I'm also thinking of lessening the eccentric offset of the 10mm hole by a few mm to allow for more control when tensioning, as you mentioned and as i've found out it's bloody sensitive! Not too much or it will make installing the belt a little hard for some but just a little. Enlarging the diameter of the shoulder would be nice so it butts up against the full spot face on front seal housing.

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 Posted: 11-22-2016 05:58 pm
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qwerty wrote:
I'm also thinking of lessening the eccentric offset of the 10mm hole by a few mm to allow for more control when tensioning, as you mentioned and as i've found out it's bloody sensitive! Not too much or it will make installing the belt a little hard for some but just a little.I agree the eccentric tensioner would be much better if it wasn't so hyper-sensitive to adjustments. A wrenching buddy and I have talked about doing the same thing, but we've gotten no further than talk. The issue is that you're splitting hairs between 1) not having sufficient travel to achieve enough tension on a range of belts, and 2) being way too hyper-sensitive.
qwerty wrote:
Enlarging the diameter of the shoulder would be nice so it butts up against the full spot face on front seal housing.
The shoulder that touches the boss on the seal cover can't be enlarged. It presses through the bearing bore from front to rear, so bore-size is as big as it can get.

Regareds,
Tim Engel

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 Posted: 11-22-2016 06:25 pm
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The shoulder that touches the boss on the seal cover can't be enlarged. It presses through the bearing bore from front to rear, so bore-size is as big as it can get.
Heyyy? Not sure we're on the same page here. See pic below.

1) not having sufficient travel to achieve enough tension on a range of belts, and 2) being way too hyper-sensitive.
3) I trust Lotus did their homework on the offset as well so i'm mindfull of that too.


Attachment: 1.jpg (Downloaded 99 times)

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 Posted: 11-22-2016 07:42 pm
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qwerty wrote:
Heyyy? Not sure we're on the same page here. See pic below.Brain fart, or brain not engaged. You're right.

Later,
Tim

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 Posted: 11-25-2016 12:51 pm
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Jensen Healey specific hub coming along nicely. Directly squared over the crank pulley. Next we mill the hex, given the design it will be a 24mm Hex instead of a 22mm Hex. Pictured here in Ali but the final will be 4140 Steel possibly coated/treated for corrosion.

Attachment: J-H Eccentric Hub 1.JPG (Downloaded 83 times)

Last edited on 11-25-2016 02:02 pm by qwerty

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 Posted: 11-25-2016 12:52 pm
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Jensen Healey Specific Manual Eccentric Hub

Ditch the 2x 6005's and replace with the superior 1 piece Timing Belt Bearing SKF 414871A or the Flennor FS03299 (as pictured) Either will fit.
  • Full concentric abutment with spot face on the block increasing rigidity.
  • Full concentric abutment with spot face on the block reducing carving of block spot face upon multiple readjustments.
  • Centralized Adjustment nut allowing normal spanners.
  • Protruding hex to allow for easier spanner fit.
  • Hard shoulder while pressing in to avoid misalignment with crank sprocket.
  • Reduced radial offset yet increased OD of roller to allow for more forgiving adjustment.
  • Wider Roller over the Stock J-H Shell.
  • Increased Diameter over stock J-H Shell.

Attachment: J-H Eccentric Hub 2.jpg (Downloaded 84 times)

Last edited on 11-25-2016 01:56 pm by qwerty

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 Posted: 11-25-2016 01:33 pm
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Jensen Healey Specific Maual Eccentric Hub

Attachment: Jensen Healey Eccentric Tensiioner.JPG (Downloaded 81 times)

Last edited on 11-25-2016 03:57 pm by qwerty

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 Posted: 11-25-2016 02:00 pm
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Front View: Untensioned

Attachment: Jensen Healey Eccentric Hub.JPG (Downloaded 82 times)

Last edited on 11-25-2016 02:06 pm by qwerty

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 Posted: 11-25-2016 05:41 pm
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Nice Work! I'm impressed.

Tim

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 Posted: 11-29-2016 09:27 am
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Thanks Tim,

I've started a new thread on this as we have the final version done.

I did a check on a worn belt: Static tensioned at 140-160LBS on an old belt still had 60deg of rotation to go to max tension and 3mm of growth on the od of the roller.

Regards
Pete

Last edited on 11-29-2016 09:30 am by qwerty

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