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peteyg

S2 Engine Mounts - options?

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Just had another right hand engine mount split. Oddly you'd expect the left hand to be the weaker with the exhaust heat but no, it seems I have to keep breaking the right hand one. I have ordered a replacement from SJS (where the previous one came from) but wondering if there are any other suppliers that might be offering a better made product? 

Pete

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Hello Pete,

Which type of mount are you using?

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All the engine and transmission mounts have to be in good nick on Esprits without the upper control arms, like your S2. Are the other three mounts sound?

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On 15/10/2018 at 17:17, drdoom said:

Hello Pete,

Which type of mount are you using?

The standard ones. I tried the SJ modified ones but kept melting the bushes despite heatshielding efforts.

On 15/10/2018 at 17:47, CarBuff said:

All the engine and transmission mounts have to be in good nick on Esprits without the upper control arms, like your S2. Are the other three mounts sound?

Good point. Not sure how easy it is to check the other mounts without removing gearbox? They were fitted about 18years/60k miles ago so possibly need replacing...

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Pete,

I am for a number of reasons very pleased to have chosen an early Esprit however the engine mounts are one truly dodgy area of concern. I too have purchased the SJ upgrade kit and while they are just one more project awaiting my attention it comes as no surprise to read that you've had the issue with meltdown, presumably on the exhaust side. One has to wonder why the juicy polyurethane bits would not have been better located at the lower end of the mounting leg, particularly on the exhaust side. The biscuit rubber type, which Lotus settled on after first cars were produced using a form like that which SJ emulate with their kit, are well known for limits in performance and durability. Clearly there is ample room for improvement and I am altogether pleased to explore the alternatives.

Resourceful, notably competent American enthusiasts long ago developed 2 noteworthy fixes, 1 rudimentary and the other quite elaborate. Simplest mitigation retained the biscuits and added a steel link with Rose joints between an upper bellhousing bolt and a bracket affixed to the chassis directly aft of that. It's a rather rude and inelegant fix that Lotus nonetheless adopted as a kit with Service Bulletin for owners so inclined. The more comprehensive approach replaced the biscuits with Esprit Turbo mounts carried in brackets and struts custom designed to adapt to the early chassis attachment points. Both solutions are reported to have salutary benefits to handling. Conversion to the Turbo type seems to be the definitive and conclusive resolution and I would be happy to go that way were in not for the steep price the suppliers are seeking for their kits.

When I am free to continue work on the car ( home renovation contractor tore out the front porch, stairs and walks then had a fitful meltdown, leaving me to deal with it all ) I will entertain any combination that seems promising, perhaps starting with a rework of the SJ kit to place the poly bits further out of harms way. The proximity of the exhaust is in all cases our nemesis on the exhaust side but both biscuits come under excessive stress in use as designed, with corresponding harm to the transaxle mounts which should otherwise be very long lived.

Best regards

 

 

Pete,

Have you considered leaving your exhaust side biscuit in service and fitting the SJ poly arrangement to the right side? Why not give that a ride?

Cheers

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Hi Steve,

All very interesting! I'll probably start with replacing the gearbox mounts and see if that helps as they're probably overdue. 

Good luck with the porch!

Pete

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Thanks for the support, Pete, this forum community provides most welcome distraction from the toil.

Having observed the motor reactions on the mounts from the passenger seat, engine cover absent and driver giving it the boot, I noted a very pronounced upward/forward thrust of the motor's forward end. This is typical of the torque reaction resolving between tire contact patch and the axle centres against restraint by the motor mounts. It seems that the transaxle hanger bushes are not designed to weigh into that set of forces, rather they are more central to the containment of corner loads translated through the axles, lateral links, top hat brace and cast hanger uprights. On the other hand, these bushes are subject to distortion when failing motor mounts permit excess forward thrust of the motor to draw the bushes out of form. When I pulled my car apart the biscuits were found to have taken a markedly permanent set consistent with the powertrain having shifted forward. Altogether agree with your keeping the lot in good nick, as Atwell rightly suggests, but I believe it necessary to consider how best to restrain the powertrain's torque reactions by way of the motor mounts.

Cheers 

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Hi Pete,

If you say "split" , do you mean that one plate is teared of the rubber block ?

If so, I had the same problem in the past with old and new blocks and I have a , well call it creative, solution that uptil now did a pretty good job.

I first glued the plate to the block with some flexible mounting kit. This is in no way strong enough of course, but next I drilled 3 holes with a small drill through the plate and into the rubber . Next I put in 3 firm screws. You have to make sure , the screws sit at least 5mm away from the opposite plate. Use the right lenght, or schorten whatever scew you use at the right lenght. Strangely enough, you can really pull the screws and plate very strong into the rubber block.

I did this modification as a temporary solution, but it seems to just do the job.

On the picture you can see I did countersink the screws in the plate.

image.png.5604f22cb33fc935b69ca7cb0ff8be70.png

 

Geert

 

Edited by gvy
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Cool topic. @drdoom you don't by any chance have any reference images of the two fixes, or know where I could look?

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This is the kit as offered some years ago, picture courtesy of Tim Engel as I recall. Possibly sourced from Lotus Prepared by Claudius. Both Lotus PBC and JAE can still supply something of the sort.

                                    160420083_Esprit907EngineMountTurboConversionKitPARTS.jpg.bf20bdb868b5c30f5ac618b1a1f4da8d.jpg

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I'll also attach a drawing of modification to one of the mounting legs, found to have been needed by the early adopters.

As to the simple torque stay link with Rose joints that was developed by arch enthusiast Kiyoshi Hamai and drawings for that were available at the Golden Gate Lotus Club website.

Engine Mounts - Mounting Arm, Modified Exhaust Side Arm.pdf

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Thank you Steve!

I'll attach the second diagram for ease of ref for future readers, and I found the page you spoke of with the rose jointed stay here.

It's all eminently doable.

Screen Shot 2018-10-19 at 08.33.18.png

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Cleaned up Kiyoshi Hamai's diagram from gglotus.org for easier ref, 'Tranny mount' means something else in some parts of the world 

Esprit Engine Brace.jpg

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Quote

" . . .  Tranny mount . . . "  :rofl:

snowflakes are melting . . .

the Poles too become water

binary world wilts

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1 hour ago, drdoom said:

snowflakes are melting . . .

the Poles too become water

binary world wilts

Is that your own? 😎

here's mine;

 

Oh for just one snap

the rare Esprit engine stay 

nary seen online

 

Have you ever seen one in the wild?

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Yup, that was mine. Snowflake zeitgeist on the mind with all the prattle about gender fluidity in our media these days. BTW, wife is yukking it up with snipes about us exchanging poems, or "sonnets" as she called the Haiku.

Nope, never seen the like of the simple stay. On that, one should take into account the unyielding nature of such an all metal assembly. It likely would provide a very acute path to chassis for engine NVH, and the chassis should at minimum have fitted the angled struts (absent in the earliest cars) between trans hanger and the motor mount locations.  

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6 hours ago, drdoom said:

BTW, wife is yukking it up with snipes about us exchanging poems, or "sonnets" as she called the Haiku.

My heart aches in pain
When I see you I vomit
Die away from me

MrsDoom can be proud that you started it. 

6 hours ago, drdoom said:

...take into account the unyielding nature of such an all metal assembly. It likely would provide a very acute path to chassis for engine NVH...

I was thinking the same thing about the stay, and looking for photos to get a definitive on exactly which side and which bell housing bolt the stay is fitted to. It must run north-south in the bay and as such stays the engine in the same direction. I'd be more concerned about repetitive load being driven into the chassis crossmember. I wonder would a setup the likes Ive used on Mini engines work? Something like this is off the shelf.

@peteyg sorry for the hijack, any progress?

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Mrsdoom was LOL upon hearing your latest verse, George. She's just a bit twisted.

That Mini kit is just about the sort of thing I'd try as an engine stay, were that on the cards. As stated earlier I'm thinking of trying the SJ poly on the cold side. Exhaust side still to be determined, torque stay not out of the question. Trusting that we are  not straying off course in terms of Pete's concerns, it interests me to discuss the matter of NVH as a whole. One mate explored the infamous resonance, well apparent in his and brother-in-law's S1's, through substitution of several silencers. He had fitted a big bore 4-2-1 manifold and DCOE's breathing noisily through K&N filters. The thing made a simply glorious angry symphony of noise at full chat, but the booming resonance was worse, not helped at all by use of a "Turbo" style, reverse flow baffled silencer. Next up was a straight flow, drag race muffler that reportedly worsened the resonance but announced buddy's imminent arrival from quite a distance. What was eventually settled upon was the Supertrapp brand diffuser disc assembly, which emulates the form and function of a trumpet mute. Very compact as mounted on the shortest collector pipe, and most agreeable to the torque output curve with quite the reduction in the resonance! Aesthetically not to everyone's taste, lacking the gaping pipe end bore of more conventional mufflers, though. Cheap and absolutely durable, by the way.

One question worth considering is establishing what proportion of the dreaded resonance is down to direct acoustic excitement of the car's light, GRP bodywork. I've got a bare shell on trolley cart in the garage and to tap one's knuckle on most of the panels is to gain appreciation for what a drum we have in these Lotus bodies. It takes just a bit of exhaust fiddling to incite the most almighty resonance into any car, even in all metal unibody form. I once had a shop fit dual path "Turbo" mufflers to a Capri V-6 and it resulted in a head-throbbing resonance on overrun in the lower revs that shook the rearview mirror to the point of uselessness. The typical crossover pipe was then added to little benefit so we reverted to OEM configuration, with the single path for all 6 back to a single "Turbo", and that was not at all troublesome. So I shall be trying to head off acoustic energy early in the scheme of things - e.g. thickly laying on dampening mat to the inside of the exhaust side tank well and vicinity.  

It is the conventional view that the NVH improvement greatly realized in the S3/Turbo series was down to the revised powertrain mountings and, while that must be true to some extent, one must wonder whether other methods were employed which significantly contributed. The newer p/train mountings fully resolved what was undoubtedly a tendency for the early cars' arrangement to perish prematurely, so that wasn't entirely about the resonance problem. I believe there was a notable increase in weight of the S3 over the early cars, yet the major components were all pretty much equivalent. So thicker body panels? Bulkier acoustic deadening mats?

Fair weather beckons me outside to reno chores. Catch up with you good lads later.  

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Mount replaced. Don't think this is going to be going back on with any mods...

44655325935_cdb6f0ecbd_c.jpgIMAG3172 

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