Original front shock absorbers

[NickC]

Anyone got a pair of new original front Excel shock absorbers that we could use to measure the compression/rebound rates?

I have been discussing getting some Koni shocks to fit but need to see if they can be made with the correct rates.

Thanks,

[Pjr]

Nick,

Unfortunately I dont, but i think its an excellent idea - i would love some original spec shocks and springs because i want to experience handling as Chapman intended. Perhaps it might be worth asking to borrow rear ones as well as a car set would give the Most authentic setup.

Best if luck,

Phil

[richardw]

I have a single new old stock original oil filled damper that I would be happy to make available for a calibration exercise. I started a similar project a while ago but came to the conclusion that my Lotusbits coilovers with rubber seats added would do the job. They were calibrated against a range of original dampers I believe, but as they are gas filled they will also have some spring effect.

Any ideas who could do the calibration exercise?

ATB Richard

[AndyC]

The strange thing about the gas vs oil different spring effect is, that for the Esprit range Lotus started (got part way and stopped) to produce gas dampers to replace the old unavailable original ones, and were tuned to give as authentic as possible handling as when the car was designed. Just odd, that they managed to tune things to not be different despite the extra springiness.

[richardw]

The strange thing about the gas vs oil different spring effect is, that for the Esprit range Lotus started (got part way and stopped) to produce gas dampers to replace the old unavailable original ones, and were tuned to give as authentic as possible handling as when the car was designed. Just odd, that they managed to tune things to not be different despite the extra springiness.

Interesting - I believe that when Lotus switched to gas shocks on the Excel, the spring rates were unchanged. Perhaps, as the fashion was for stiffer suspension on sporting cars, a little extra firmness didn't matter and helped keep the car feeling up to date.

Richard

[NickC]

I have a single new old stock original oil filled damper that I would be happy to make available for a calibration exercise. I started a similar project a while ago but came to the conclusion that my Lotusbits coilovers with rubber seats added would do the job. They were calibrated against a range of original dampers I believe, but as they are gas filled they will also have some spring effect.

Any ideas who could do the calibration exercise?

ATB Richard

That would be very helpful thanks Richard. Will be in contact when I get to the point of needing the actual calibration.

[NickC]

Interesting - I believe that when Lotus switched to gas shocks on the Excel, the spring rates were unchanged. Perhaps, as the fashion was for stiffer suspension on sporting cars, a little extra firmness didn't matter and helped keep the car feeling up to date.

Correct from what I have established the springs were all the same spec, the later part number was just a tightening-up of the spring tolerance, no change to the actual rate.

Years ago I had a pair of the original Lotus supplied gas filled shockers, from what I recall it did provide positive pressure expanding the shock but was so minimal that they could still be pushed together by hand.

Lets remember that gas filled shocks still use oil, it is just that the free expansion space is filled with gas rather than air.

I would therefore suspect that the expansion force from the gas is so minimal as to cause the car to ride no more that 0.5mm higher, just my guess.

[NickC]

Nick,

Unfortunately I dont, but i think its an excellent idea - i would love some original spec shocks and springs because i want to experience handling as Chapman intended. Perhaps it might be worth asking to borrow rear ones as well as a car set would give the Most authentic setup.

Well if anyone has any new original rear shocks I would be happy to try and get them made as well.

Just that from my point of view I would like to see how the fronts turn out before committing more money to getting the rears developed at the same time. That said if anyone has suitable rears I would be happy to try and get them specified for manufacture at the same time.

[MikeC]

Anyone got a pair of new original front Excel shock absorbers that we could use to measure the compression/rebound rates?

I have been discussing getting some Koni shocks to fit but need to see if they can be made with the correct rates.

The Koni importer in 1985 (Banks, Crowland) was given the full set of Armstrong dampers from my Excel to replicate them. After which I had a set of Konis at cost. Still have three on the car, so possibly I could remove one.

Mike

[smithersoli]

I have just removed a set of dampers and springs from my vehicle, they look pretty new and in decent condition and seemed to be working well, but I have upgraded to Mike's Coilover kit.

Am willing to donate the dampers for review if someone is taking them to a professional.

I would prefer to sell the springs as my wallet is hurting, and they are in good re-usable condition. ( I suspect both dampers and springs were new about 4k miles ago 9 but maybe 8 years when the car underwent a full refurb) but will check part numbers tonight to identify them.

O

[NickC]

mikec:
Thanks for that, might be good to measure them but results could vary, depends how well Koni replicated the original rates when they made those for you back in 1985.

smitherssoil:
If they turn out to be original Lotus shocks one of the rears might be good to measure.

Lets see how we get on with getting the fronts specified, possibly using richardw's new original front shock. If that is looking ok and price is sensible then give them one of the rears as well.

[MikeC]

mikec:
Thanks for that, might be good to measure them but results could vary, depends how well Koni replicated the original rates when they made those for you back in 1985.

Well, being Konis you had to get them off the car, compress and twist them, but IIRC about 1 turn from fully soft was similar to the OEM Armstrongs and about 4 turns up was good for the track. At this sprint <https://www.flickr.com/photos/54731504@ ... 897306086/> I wrote for the commentator's notes that the car had "162,000 miles of gentle running in" of which the Konis had then done 130,000 miles. Third in over the 2-litre class in a boggo Excel on Goodyear NCTs can't be bad against the "County Championship" Beemers on race tyres.

But I'm not sure that today's Konis are the same. Nor am I, or my Excel ((


Mike

[NickC]

Possible progress - we have found some maybe suitable Koni's but open/closed lengths are a bit different:

Lengths:
Closed - original: 242mm, koni: 230mm = diff: 12mm x 1.9 = 23mm higher at wheel
Open – original: 302mm, koni: 326mm = diff: 24mm x 1.9 = 46mm lower at wheel

Would this extra movement cause any problems.

[smithersoli]

I have the shocks and springs off my car for review if anyone wants them. Part numbers and general condition would suggest they were new in around 1999-2000 when the po did a lot of work to the car. There is even the remains of a paper sticker on one. A wipe over with a rag brings them up clean with only minor surface corrosion. Anyone interested please pm me an email and will send them as am on an iPhone and can't attach to a web hosting site at the moment.

[Lotus-e-Clan]

Any progress on this?

I'd like to replace dampers all round - would be brilliant to have a set of non-adjustable original dampers with the correct rates, bump stops, covers, and operating lengths.

I've found issues with most brands of replacements over the years - the latest being the GAZ rears on the Excel which started to knock and now have split their bump stops after a 4-up (adults) country lane journey. Seems that the bump stop lengths and damper body size is not OEM so the rears hit the bump stops all too often..

btw We've had the same 'knocking issue' with GAZ in the ImpClan world so there's probably a service life quality issue.

Protech adjustable replacements seem better in many respects but leave room for doubt. To be fair, I think most aftermarket dampers use a universal compromise for bump/rebound.ratios and it's 'pot luck' if they properly damp OEM loads and spring rates without compromising ride quality.