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Belt idler pulley and bearings.  Rate Topic 
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 Posted: 05-04-2016 08:00 pm
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Frank Schwartz
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I just removed the idler pulley and eccentric from a GT that is so rusty all that is worth saving is the engine and transmission etc. The idler pulley is different from earlier Lotus engines in that it seems to be the entire unit as one piece..the bearing and the running face (I guess you call it) seems to be a one piece unit. I have seen idler pulleys from other cars that were all one piece. Does anyone know if this unit is an over the counter item...or only available from Delta??
They show a different unit (this one) for 75 and GTs vs earlier JHs.

Thanks,
Frank

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 Posted: 05-05-2016 12:58 pm
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Brett Gibson JH5 20497
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Frank, it's a one piece unit and purchased whole, I have one on my JH5, I did cross reference it some time ago and the cost was about the same as Delta, basically not worth the trouble, runs about $75 if I remember correctly.
Brett

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 Posted: 05-05-2016 03:29 pm
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Esprit2
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Frank,

Jensen-Healy 'assembled' eccentric tensioner
Industry Standard ball bearings, such as ...

INA 6005-2RS
ID .............. 0.9843" (25mm)
OD ............. 1.8504" (47 mm)
Thickness: ... 0.4724" (12 mm)

Two of the 6005 ball bearings are assembled inside a proprietary outer steel ring/ roller, and with an eccentric hub pressed through the bores. The hex head for adjusting the eccentric is between the tensioner and the block, so access isn't as easy as it should be.

All "Lotus" tensioners (eccentric and spring-loaded) used a dual row/ double width, integral bearing/ roller. The bearing IS the tensioner roller.
ID ........... 1.214" (30.8356 mm) ... did the math and
OD .......... 2.478" (62.9412 mm) .... kept the decimals
Thickness: 1.179" (29.9466 mm)

SKF .......... 414871A ... Excellent quality, my favorite
SKF .......... VKM 14300 (??) In general, SKF is a quality brand.
Flennor ..... FS03299 ... Now sold by JAE
Ford ......... 1500004 ... 1977-1986 Ford Transit Van
INA .......... 531 0098 20 (??) In general, INA is a quality brand.
Timken ..... TKR 9841 (??) Timken production is in China.

Early Lotus Eccentric Hub ... P/N A907E0684FB
Later Lotus Eccentric Hub ... P/N A912E2176F
Either Lotus hub will work with the above bearings. I believe the significant difference was the size of the adjuster hex. The Lotus eccentric has the adjuster hex head on the front side. No special, thin, bent wrench required.

*~*~*
NOTE: There are minor dimensional differences between the JH and Lotus versions of the front seal housing. Due to those differences, the Lotus eccentric is not a direct plug-n-play upgrade for the JH 907. However, if you also swap in the Lotus front seal cover, then the Lotus tensioner will fit your JH engine. "OR"... Joe Van Ruth, 'qwerty' on this forum, has made up a Lotus-style eccentric that accepts the integral bearing/ roller, and fits the JH front seal housing. He sells them as a group buy on JHPS and the Jensen Healey Facebook page.
http://www.jensenhealey.com/forums/view_topic.php?id=2356&forum_id=2
*~*~*

DO NOT buy bearings by price. There's some cheap crap out there. If the bearing fails, it will take out the timing belt, and then the pistons wipe out the valves. "Cheap" can be really, really expensive.

Some new bearings feel rough out of the box. Hand try it before you buy it. Buttery smooth is what you want. Some of the Chinese bearings, in particular, have no business being anywhere close to a J-H/ Lotus timing belt.

Last edited on 07-10-2017 08:51 pm by Esprit2

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 Posted: 05-06-2016 07:52 am
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Frank Schwartz
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You have me confused. I am familiar with the two bearing tensioner for the JH. I refer, however, to the single bearing unit which is a complete unit (less the eccentric) and is in the 75 JH and the 76 GT... Hopefully, I can find one of these as an over the counter unit...

Perhaps one of you has a part number for that one..
Frank

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 Posted: 05-06-2016 12:46 pm
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Brett Gibson JH5 20497
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Frank, Tim did supply the bearing numbers if you want to try over the counter.
SKF .......... 414871A ... Excellent quality, my favorite
SKF .......... VKM 14300 (??) In general, SKF is a quality brand.
Flennor ..... FS03299 ... Now sold by JAE
Ford ......... 1500004 ... 1977-1986 Ford Transit Van
INA .......... 531 0098 20 (??) In general, INA is a quality brand.
Timken ..... TKR 9841 (??) Timken production is in China.

Brett

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 Posted: 11-06-2016 08:09 am
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qwerty
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Just approched this bearing today, looks like i have the integrated (once piece) roller AND it's installed up side down.

I'll see what i can get hold of tomorrow, Frank did you sort yours out? If not i will order two and send you one.

Attachment: Capture - Copy.JPG (Downloaded 150 times)

Last edited on 11-06-2016 08:11 am by qwerty

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 Posted: 11-06-2016 08:20 am
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qwerty
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Does that look pretty bloody loose too? I haven't touched it.

Attachment: Capture.JPG (Downloaded 148 times)

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 Posted: 11-06-2016 02:27 pm
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redracer
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Frank: I usually retrofitted the older style tensioners(concave outer surface as opposed to the flat integrated later style) since changing the 2 bearings was easier, faster, and cheaper than replacing the later one piece design; but if they are readily available and not too expensive, then look at the ones Brett & Esprit mentioned

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 Posted: 11-06-2016 03:22 pm
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Frank Schwartz
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From the picture, it looks correct...and it appears to be the two bearing type....I do not understand how it could be "upside down"... Remember, to remove it, you will have to slide off the crankshaft pulley....
I still have the single bearing unit on my bench and have not replaced the single bearing in it yet.

I have been working on Mike Linn's daughter's JH and just when I thought I was finished inside, I found the fan frozen and had to take the entire inside out to replace it. Also found many electrical problems that I had to fix...wiring on early JHs is not the exact same as later models, I found out....

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 Posted: 11-06-2016 04:05 pm
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Screenplay
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Is the "upside down" a reference to the position of the eccentric? The pic looks like it's installed according to the WSM - that is, tension is increased by turning the eccentric nut clockwise. However, as I recall Tim Engel has posted a tuotial recommneding turning the eccentric 180ยบ so tensioning is increased by turning counterclockwise - I believe a failsafe in case the nut loosens.

Or perhaps it just looks upsidedown because qwerty is on the opposite side of the eqautor from many of the commentors here.

Clinton

Last edited on 11-06-2016 04:05 pm by Screenplay

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 Posted: 11-06-2016 04:40 pm
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qwerty
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Yes the upside down is a reference to the eccentric, nice one Clint, that may be why my lower A arms are back the front with the sway bar mounts pointing forward. :)

Upside down refers more accurately to being 180 degrees out or the bearing running closer to the aux pulley. Apparently we can install with the bearing center in either position (closer to the Aux pulley or closer to the Crank Pulley).

There are reasons for installing it closer to the crank pulley. In my picture above with the bearing closer to the aux sprocket imagine if the bearing spinning in it's normal anti-clockwise rotation and seizes/semi seizes or the lock nut starts to fail, the belt will loosen the stud (i'm assuming it's a stud) going into the block or the tensioner nut. The tensioner will swing away and the belt looses all it's tension and we don't want to talk about that. Additionally timing belts are not always uniform tension as it runs around the belt train, when the tension incrases it will apply force to the swinging action that is away from the belt and that swinging action would be anti clockwise this variation could slowly loosen off the threads over time.

Installing with the bearing center (blue dot) below the stud (big orange blob) in the image below (ie the bearing is closer to the crank pulley) and any of the above happens it will mitigate the risk of loosening the belt due to the pulley swinging (orange blob being the pivot point) into the belt and maintaining some tension until you pull over after hearing some god awful bearing noise from under the bonnet. Looking at the WSM it also looks to be dead center between the two sprocket diameters  when installed closer to the crank pulley.

Still looks like a one piece jobby to me, i'll check it out tomorrow. If it isn't i'll be equally as happy as i have ABEC3&5 6005's on hand.

Anyhoo i hope this helps. Besides i think i've hit a new PB on the number of times i've edited a post.

Attachment: Belt Tensioner.JPG (Downloaded 141 times)

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

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 Posted: 11-07-2016 05:46 am
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Esprit2
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When tensioning the timing belt, rotate the eccentric counter clockwise (as viewed looking at the front of the engine). If the eccentric is turned clockwise, it will tend to back-off in normal use, while counter clockwise stays put.

Do it wrong and you'll have belt tension problems long before the bearing seizes to the point of being able to screw the stud out of the head.

Regards,
Tim Engel

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 Posted: 11-07-2016 07:01 am
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qwerty
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Thanks Tim, good rule to start with.

Here is mine in the WRONG position, has been like this for some time!!

Attachment: Wrong Position.JPG (Downloaded 129 times)

Last edited on 11-07-2016 07:04 am by qwerty

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 Posted: 11-07-2016 07:03 am
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qwerty
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And now in the CORRECT POSITION

Attachment: Correct Position .JPG (Downloaded 128 times)

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 Posted: 11-07-2016 04:39 pm
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Screenplay
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Qwerty,

I, too, ran one for many miles in the wrong position as I was following the instructions in the WSM. Thanks to Tim's tip It now looks like yours in the correct position.
I wonder if Lotus made this reccommondation in a later manual on the Esprit or if it's one of those things owners figured out over the years?

I also have a question: My current project, #18341, has a timing belt that rides near the rear edge of all of the toothed gears - cams and oil pump/distributor drive. Yet on other cars the belt rides in the center of the gears. Does anybody know why? Any thoughts on this?

Clinton

Last edited on 11-07-2016 04:41 pm by Screenplay

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 Posted: 11-08-2016 12:45 am
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qwerty
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G'day Clint,

I thought the same abou the WSM, maybe this is why there were a few belts jumpimg teeth in the past. I posted up in detail for newbies like me for future reference as there's no one spot on the internet that explains it all, Just what's the right way and what's wrong way but not the why.

Tim's rule of rotating the eccentric counter clockwise nailed the what to do part.

Thoughts on your belt running at the back and relying on the principle of aligning a belt on a linisher/belt sander.

Only thing i can think of is that one or more of the sprockets in the belt train is out of alignment? The running surfaces need to be parallel and i'd imagine a hard problem to diagnose. You'd have to lean one of the cog's top forwards to have the belt run to the back side of the pulley.

I'd rule out the cams and the crank as they are mounted pretty solid. Is the tensioner stud bent at all? The Aux pulley could be out due to permatex etc build up on the oil pump/dizzy assembly gasket at the back.

Place a steel rule vertcally over all the sprockets and compare looking side on and see if the Aux sprocket is leaning forwards. The difference would be hardly noticeable so the longer the ruler the better.

Hope this helps.

Last edited on 11-08-2016 12:47 am by qwerty

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 Posted: 11-08-2016 02:17 am
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Esprit2
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Screenplay wrote:
I, too, ran one for many miles in the wrong position as I was following the instructions in the WSM. Thanks to Tim's tip It now looks like yours in the correct position.
I wonder if Lotus made this recommendation in a later manual on the Esprit or if it's one of those things owners figured out over the years?
Lotus did add the instruction to later manuals. As I recall, the word was pretty well distributed via TSB's and the dealer network prior to making it into the manuals, but it did end up in print.

The 9XX engines continued in production for another 20 years or so after the J-H & GT went away. A lot more was learned about the engines than appears in the J-H WSM. Experience later showed that some early specs, like the recommended timing belt tension, were inadequate. It would be wise for J-H owners to have the "Engine" section as well as "Technical Data Section A" from later Lotus manuals. Not that every word applies directly, but there's good general info that can be useful.

Regards,
Tim Engel

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 Posted: 11-08-2016 02:32 am
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Esprit2
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Screenplay wrote:
I also have a question: My current project, #18341, has a timing belt that rides near the rear edge of all of the toothed gears - cams and oil pump/distributor drive. Yet on other cars the belt rides in the center of the gears. Does anybody know why? Any thoughts on this?Belt tracking wasn't perfect in the beginning, but it wasn't far off. In the late 1970's ('79 ?), while 'metricating' the engine, Lotus modified the hub's width to better center the pulley's position under the belt's track.

But that's a small thing. If the belt is tracking way off center, then that does indicate that some shaft is off-axis somewhere... but there isn't just one scenario. It can be the tensioner bearing stud, as mentioned, but the cams are the more common source. Everything was pretty straight & true from the factory, but if the head has ever been milled to 'fix' a warp, then it's not uncommon for the new surface to not be parallel to the cams.

Also, when a head warps, the whole thing goes banana shaped, not just the bottom face. Truing the bottom doesn't straighten the top, and the cams may go cross-eyed.

Similarly, if the block has ever been decked or align-bored, it's possible that axis alignment was lost somewhere.

If the belt is running off the edge of the pulley, then that's a problem. But if it's just running a little off-center, but still on the pulley, don't sweat it. It's okay.

Regards,
Tim Engel

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 Posted: 11-08-2016 12:47 pm
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Brett Gibson JH5 20497
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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.

Brett

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 Posted: 11-09-2016 06:09 am
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Esprit2
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Here is the page from the Lotus Esprit Turbo manual that talks about turning the eccentric tensioner counter-clockwise to tighten the timing belt.

To get the eccentric hub above the pivot bolt, as shown in the left illustration, it would have to be turned clockwise... which is not correct.

To get the eccentric below the bolt, as in the right illustration, turn it counter-clockwise.

Regards,
Tim Engel

Attachment: 9XX Timing Belt Tensioning - Esprit SE, S4, S4s, Section EF, pg 19 - 100kb.jpg (Downloaded 97 times)

Last edited on 11-09-2016 06:54 am by Esprit2

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