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Belt idler pulley and bearings.  Rate Topic 
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 Posted: 11-09-2016 06:13 am
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Esprit2
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Or, shown another way...

Attachment: 9XX Timing Belt - Routing & Tensioner Direction - 98kb.jpg (Downloaded 92 times)

Last edited on 11-09-2016 06:57 am by Esprit2

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 Posted: 11-09-2016 06:58 am
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Esprit2
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Brett Gibson JH5 20497 wrote:
I am in the process of bolting things back onto my rebuilt engine, and in doing so when I looked into the belt tension-er whole to put the stud back in, I noticed that the new front cover gasket was protruding slightly into the whole on just one side. Thinking this might put the tension-er bearing slightly off kilter I cleaned the bit out of the whole. Could this be an issue on just were the belt run's, I don't know, but the thought crossed my mind.That shouldn't be a problem.

Regards,
Tim Engel

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 Posted: 11-09-2016 08:58 am
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qwerty
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Tim would placing a bit of threadlocker (Loctite Medium Strength 243) on the stud into the block be a good idea? I noticed while tensioning mine the stud backed off while going counter clockwise.

EDIT: As per Tim's advice below and after removing the tensioner and understanding how it is held in place, Loctite is definitely not required.

Stud hole depth is approximately 30mm and thread on the stud is 25mm long. The stud threads in and seats on the shoulder of the stud thread, not bottoming out in the hole of the block so it will gradually tighten and not be a solid bottom out.

I threaded mine in until i felt a slight increase in torque and stopped there.


Last edited on 11-13-2016 04:22 am by qwerty

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 Posted: 11-10-2016 07:02 am
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Esprit2
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It shouldn't be necessary. If you don't have a specific issue that needs a bandaid, then avoid using Loctite on studs (or bolts) into the block or head (any aluminum casting) unless it's called for in the manual. If you ever damage the external threads on a stud that's Loctited, then you'll have a heck of a time getting it out. It's hard to heat that much mass hot enough to kill the Loctite, and if you succeed, then the required temperature puts the aluminum at risk of being annealed.

I've never had the tensioner stud back out, but the Nyloc nut can loosen if the tensioner is turned in the wrong (clockwise) direction to tighten the belt. It's a simple thing to turn the tensioner counter-clockwise. Just do that and forget the Loctite.

One exception to no Loctite in the block is the three engine mount bolts in a triangle pattern on either side of the block. Those bolts do tend to loosen, so apply some blue, medium strength Threadlocker.

BTW, never add Loctite to a Nyloc nut. It attacks the Nylon patch inside the nut, causing it to degrade and lose it's grip. It's a chemical compatibility thing, not a lock/ don't lock thing.

Regards,
Tim Engel

Last edited on 11-10-2016 07:05 am by Esprit2

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 Posted: 11-10-2016 07:43 am
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qwerty
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Thanks Tim,

No specific issue other that observing that the stud was rotating as well as the hex adjuster while removing. Remember i adjusted it the day before from an incorrect position to correct (anticlockwise) position this may have loosened the stud hence my question. I've never had a problem with 243 removal and never required heat to get it off. As noted never put Loctite or any compound on a Nylock. Being Nylon it will absorb moisture over time and expand to do a better job of locking.

I picked up some bearings today that may be worth a look at, High Temperature bearings ABEC 3, rated -30 to 150 Celsius. ( Standard bearings are rated to 80celcius) That means the seals and lubrication inside wont degrade under those temp ranges and the ABEC 3 tolerance will be a little tighter meaning less play in the roller. RPM rated at 7000.

BECO (Italian) Good stuff from experience. SKF also has equivalents.
Material Steel AISI 52100 (chrome steel) with special heat treatment stabilising
Radial Clearance C4
Quality Abec 3
Rubber seals rated for 150°c
Greased rated for 170°c

Special Application for Automotive Belt Tensioner BECO BHT 2RS 150° BTE COMP (Size 6005).

Last edited on 11-13-2016 04:13 am by qwerty

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 Posted: 11-11-2016 03:54 am
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Esprit2
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Thanks for posting about the BECO bearing. I've not heard of that one before, and I'll add it to my list.

Regards,
Tim Engel

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 Posted: 11-11-2016 07:20 am
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qwerty
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Gaaahhh.. Replaced the belt and pulley today and although the old belt was tracking almost spot on center of the sprockets before the install it now runs flush with the rear of the sprocket.

Spent a few hours trying this and that,
Bent tensioner stud:No
Rotate Stud 90Deg to see if it made a difference: No
Rotate Stud 180Deg to see if it made a difference: No
Bearings pressed in too far or too short: tried both, no difference
Rotated Idler pulley back up to the top incorrect position - a little better but not much.
Rotated back down to the correct position - running to the rear again.
Flipped belt and reinstalled with front facing back: - Still runs to the rear.
Flipped belt back to correct arrow facing forward - Running to the back
Swapped belt to the HTN Version, Runs to the rear but not flush maybe 1-2 mm off
Swapped to the Second Blue belt i have, runs maybe 1mm off the rear.

I've got nothing, the belt i took off ran in the center. Is it possible that due to the slight convex shape to the idler pulley that it will stretch in and move to center over time? I will change back to the old belt soon and see it it runs center, if it does the issue lies with the belt and not the changes. I'll report back.

Ps changing the timinng belt is acutally quite easy now that i have done it 20 odd times in 2 hours :)


Attachment: Belt Tracking.JPG (Downloaded 70 times)

Last edited on 11-11-2016 08:56 am by qwerty

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 Posted: 11-11-2016 07:21 am
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qwerty
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BECO 6005 BHT 150

Attachment: BECO 6005 BHT 150.JPG (Downloaded 71 times)

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 Posted: 11-11-2016 07:23 am
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qwerty
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Is this arc to the outer hub normal or wear?

Attachment: Arc to outer hub surface.JPG (Downloaded 68 times)

Last edited on 11-11-2016 08:52 am by qwerty

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 Posted: 11-11-2016 09:03 am
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Esprit2 wrote: Thanks for posting about the BECO bearing. I've not heard of that one before, and I'll add it to my list.

Regards,
Tim Engel

Thanks Tim, You're most welcome.

As noted SKF also has this type of bearing.

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 Posted: 11-11-2016 05:54 pm
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Frank Schwartz
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That's an interesting blue belt. Where did it come from?

All I've ever used or seen were just your everyday basic black.

Frank

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 Posted: 11-11-2016 10:42 pm
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Esprit2
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Frank,

The blue belt is from Gates Racing, a specialty division of Gates Rubber. Their part number T104RB. It's available from any Gates Rubber distributor, including NAPA, O'Reilly, and RockAuto.com.

The blue belts are the latest materials technology, including HNBR rubber (Hydrogenated acryloNitrile Butadiene Rubber). The black trapezoidal tooth belts are HCR rubber, which is ancient mid-1960's technology.

Simply due to superior materials, the blue belts should be the best available (short of converting to the round-tooth belt), and run longer between replacements. However, Lotus is not doing development/ testing work on a 45+ year old engine, and Gates won't make recommendations for other company's engines. As a result, there's no formal recommendation for miles/ months between changes, but you can think of 'using the best'as an insurance policy against failure. It costs more at about US$65-75.

Blue round-tooth belts have been around for years, but the Gates factory that had the tooling for the trapezoidal tooth belts was not configured to run the new HNBR rubber. Apparently that has changed recently, and the blue trapezoidal belt is now available.

Blue is just the trademark of Gates Racing, and it has nothing to do with the belt's materials or construction.

Regards,
Tim Engel

Last edited on 11-11-2016 10:48 pm by Esprit2

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 Posted: 11-11-2016 10:50 pm
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Frank Schwartz
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Somewhat confusing...I'll check with my local store and see if they have the blue belt. My interest was merely for a little "dress up" under the hood.

So I understand, a blue round toothed belt as Lotus uses is also available, too???

I seem to be block headed..I only know the belts as square toothed and half moon (late lotus) ...what is the trapezoid???

Thanks Tim.
Frank

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 Posted: 11-11-2016 10:51 pm
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qwerty wrote:
As noted SKF also has this type of bearing.SKF is a quality brand, and normally my first choice for bearings. But I'm always looking for quality alternatives... as well as bad alternatives to avoid.

Regards,
Tim Engel

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 Posted: 11-11-2016 10:54 pm
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qwerty wrote:
Is this arc to the outer hub normal or wear?It might be normal wear, but it was not apart of the original design or manufacture. It is 'wear'. That could be contributing to your timing belt tracking off center. The blue belt is more stiff, and would not simply conform.

Regards,
Tim Engel

Last edited on 11-11-2016 10:56 pm by Esprit2

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 Posted: 11-11-2016 11:11 pm
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Frank Schwartz wrote:
I'll check with my local store and see if they have the blue belt.Call ahead. Even if corporate NAPA/ O'Reilly's lists the belt, the local neighborhood store may not stock it. But they can order it and have it in a day or two. Or just mail order it from RockAuto.com, and save yourself some running around.
Frank Schwartz wrote:
So I understand, a blue round toothed belt as Lotus uses is also available, too???The round tooth belt is called a HTD (High Torque Drive). The Blue HTD belt that is available for the later Lotus engines is also made by Gates Racing (again, the blue is a Gates Racing trademark).

Not to put too fine of a spin on it, but "Lotus" never sold the blue HTD belt. It was an independent Lotus parts vendor, JAE, that worked with Gates Racing to develop the blue HTD belt for Lotus engines. As a result, JAE has exclusive rights to the blue HTD belt, but they distribute it to all other Lotus parts suppliers who want to buy it.
Frank Schwartz wrote:
I only know the belts as square toothed and half moon (late lotus) ...what is the trapezoid???The 'square' tooth isn't really square. The sides are tapered, and a tapered square is a trapezoid. We're talking about the same thing, just using different names.

Another advantage of the blue belt is that it's very stable. Continue to check the belt's tension on a regular basis, but it's highly unlikely that you'll ever have to re-set the tension after the initial installation.

Regards,
Tim Engel

Last edited on 11-11-2016 11:13 pm by Esprit2

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 Posted: 11-11-2016 11:19 pm
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Frank Schwartz
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I understand. Thanks...oh take a look at what I just posted on intake manifold installation, since you are sitting there at our computer.
Thanks
Frank

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 Posted: 11-11-2016 11:53 pm
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Esprit2
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qwerty wrote:
Gaaahhh.. Replaced the belt and pulley today and although the old belt was tracking almost spot on center of the sprockets before the install it now runs flush with the rear of the sprocket.
(Snip)...
Ps changing the timinng belt is acutally quite easy now that i have done it 20 odd times in 2 hours :)

IMHO, there's nothing wrong with the belt running off-center, as long as it doesn't over-hang the edge, and is stable where it is (ie, doesn't wander). If you have a little OCD kicking in, then knock yourself out. But if you're trying to fix a real problem, I don't believe one exists. Your call.

You're right... the belt is quite easy to install once you get the hang of it. But that doesn't seem to be experience most owners 'want' to get. My record for replacing the 907's belt in a front engine car is 45 minutes. The mid-engine Esprit takes considerably longer.

Regards,
Tim Engel

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 Posted: 11-12-2016 02:17 am
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Esprit2 wrote: qwerty wrote:
Is this arc to the outer hub normal or wear?It might be normal wear, but it was not apart of the original design or manufacture. It is 'wear'. That could be contributing to your timing belt tracking off center. The blue belt is more stiff, and would not simply conform.

Regards,
Tim Engel

Would one of the kits pictured (Kemp High Performance engines) be a direct replacement? They advertise this as an upgrade from the S3 auto tensioner to manual and needs an M10 thread into the block, well we already have that so this may be a good upgrade for the part above plus as a bonus the tensioner nut is integrated into the hub so no more slop when adjusting and you get a new tensioner roller with every change.

I heed your advise on the belt tracking yet as i will be doing tension testing for the Gates Blue Belt. (i now have Kriket and Burroughs gauge) i need to get the tensioner correct.

Kit is from an Esprit S3 It's Mostly the diameter and length of the spigot going into the block that needs to fit. I assume the tracking of the pulley will still be positioned to sit center of the crank and Aux Pulley. If the tensioner hole in the block on the esprit is the same as the J-H then it should fit with no issue.

Attachment: Eccentric Tension Kit (Custom).JPG (Downloaded 59 times)

Last edited on 11-12-2016 03:00 pm by qwerty

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 Posted: 11-12-2016 07:56 pm
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qwerty wrote:
Would one of the kits pictured (Kemp High Performance engines) be a direct replacement? They advertise this as an upgrade from the S3 auto tensioner to manual and needs an M10 thread into the block, well we already have that so this may be a good upgrade for the part above plus as a bonus the tensioner nut is integrated into the hub so no more slop when adjusting and you get a new tensioner roller with every change.
(Snip)...
Kit is from an Esprit S3. It's Mostly the diameter and length of the spigot going into the block that needs to fit. I assume the tracking of the pulley will still be positioned to sit center of the crank and Aux Pulley. If the tensioner hole in the block on the esprit is the same as the J-H then it should fit with no issue
That's the Lotus version of the eccentric tensioner. All the Lotus tensioners used the double-row bearing/roller, instead of the J-H assembly that uses two 6005 single-row ball bearings in a roller sleeve. 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.

Garry Kemp has simply pulled all the Lotus parts together into a kit to replace the spring loaded tensioner... plus a couple you shouldn't need. Your engine already has the stud. I don't recognize the spacer sleeve in the upper left of Kemp's picture, above the eccentric hub. I'm GUESSING, but it looks to me that he's using that as a spacer to replace the boss that is not present on the earlier front seal housing (right in the attached JPEG).

But your J-H 907's front seal housing also has a boss for a tensioner eccentric, very similar to the Lotus seal housing. The question is, are the bosses & bores the same diameters for both the J-H and Lotus designs. I don't have a J-H part here to check, but I have a Lotus eccentric hub in my hands. Just measuring with a dial caliper (what the heck did I do with my micrometer?), the male boss is 0.810 OD x 0.720" tall. Check yours.

My guess is that the Lotus eccentric is a direct replacement for the earlier J-H eccentric, and Kemp's kit gives you more parts than you need for the conversion. Before you buy, see if you can get the hub alone for less money (check SJ, JAE, etc). Then buy a bearing, washer & Nyloc nut near you. The bearing is SKF 414871A (excellent), Flennor FS03299 (now sold by JAE), Ford 1500004 (1977-86 Transit Van), 31mm ID x 63mm OD x 30mm wide. Just beware. There are some inexpensive Chinese copies out there that are bad right out of the box. One in partricular has blue seals... pure crap. I make a point of asking for SKF.

qwerty wrote:
I heed your advise on the belt tracking yet as i will be doing tension testing for the Gates Blue Belt. (I now have Kriket and Burroughs gauge) i need to get the tensioner correct.Yup, it is nice to get the tensioner correct. The belt is tightly located fore-n-aft at the crank sprocket.

The curved back side of the V-belt pulley, and the backward curved washer behind the sprocket form a 'funnel' that guides the belt onto the narrow crank sprocket. There's not much room for the belt to wander off. That set's the belt's position on the engine, and is a constant on all the 9XX 4-cyl engines. Any tracking issues at the upper pulleys is a matter of the entire belt loop 'leaning'. Early cam/ auxiliary sprockets were not centered very well above the crank sprocket, so it's not unusual for the belt to be less than centered, even when everything is 'straight'. What looks like incorrect tracking may not be the belt getting off-track. In the mid-late 70's, Lotus adjusted the width of the hub to improve the pulley's position under an otherwise straight-tracking belt.

Good luck,
Tim Engel

Attachment: Sec ED - Engine - Front Main Seal Housing - 1974-80 907 74kb.jpg (Downloaded 50 times)

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