Replicate OEM Suspension - S2/RowSE/NA(part) - Not USA

[saska]

So with 5 on the list we're at the 2 for the price of 1 (ish) for the springs anyway

I haven't put myself on the list yet as I wasn't sure how things would play out particularly with the dampers.
Thought it possible I might have to buy a set of whatever Pro-Tech comes up with to test various things on a car (like the bump stops for one).
Probably I will have a full car (dampers and springs) and also a full set of springs and a set of rear dampers (there's a pair of new Lotus dampers here bought for this project).
Springs are the main thing for me as both cars are sagged by 10mm or more and the dampers on the SE are well worn (135k miles)

[texas2201]

1. Denny - Full set (front & rear)
2. Woody - Full set (front & rear)
3. M100_DMM - Full set (front and rear) - NA
4. BFG in the BRG - Full set (front and rear)
5.Texas2201 2 rear springs if that is possible - I only recently fitted adj AVO's to the rear
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[speed-demon]

Go-on then... I'll have a set assuming they are settup as OEM and they're a better option than the Avo's? Would have been nice to loose an inch of wheel arch gap, but for me it's more important not to F-up the original ride characteristics of the Elan. And can an Avo' dealer or other be trusted with this task?

[saska]

Go-on then... I'll have a set assuming they are settup as OEM and they're a better option than the Avo's?

I don't know yet whether Pro-Tech will be able to replicate the OEM dampers. If I'm of the opinion that they are not close enough to OEM then I will say so and advise everyone not to buy. The problem with AVo's is that no one knows what setting replicates the OEM setting as a baseline to work from.

Would have been nice to loose an inch of wheel arch gap, but for me it's more important not to F-up the original ride characteristics of the Elan. And can an Avo' dealer or other be trusted with this task?

Loosing an inch of ride height on a car which only has 5.1" of ground clearance is not a trivial enterprise. One of many reasons why i'm not doing that. I've auto-crossed cars with lowered suspension, larger anti-roll bars, hot cams and DCOE Webers but that is not what this is all about. Becker & Miles did a great job on the stock M100 and replicating that is what this is all about.

Status: I've not yet heard from Pro-Tech. I'm not going to try to hurry them as the dampers are far more complex than the springs.
Martin -- a set of rear springs is no problem -- we can work out some proportion of contribution.
1. Denny - Full set (front & rear)
2. Woody - Full set (front & rear)
3. M100_DMM - Full set (front and rear) - NA
4. BFG in the BRG - Full set (front and rear)
5.Texas2201 2 rear springs if that is possible - I only recently fitted adj AVO's to the rear
6. Speed-demon - Full Set
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[Gee0]

Status: I've not yet heard from Pro-Tech. I'm not going to try to hurry them as the dampers are far more complex than the springs.
Martin -- a set of rear springs is no problem -- we can work out some proportion of contribution.
1. Denny - Full set (front & rear)
2. Woody - Full set (front & rear)
3. M100_DMM - Full set (front and rear) - NA
4. BFG in the BRG - Full set (front and rear)
5.Texas2201 2 rear springs if that is possible - I only recently fitted adj AVO's to the rear
6. Speed-demon - Full Set
7. Gee0 - Rear dampers and springs
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[Axel-F]

...it seems to me that those who already have AVO/Gaz/Protech dampers could reproduce the OEM ride height pretty accurately .... Replicating the damping is much harder ...

I was planning to go for Avo damper, already bought rear one's,

my Lotus garage told me that he didn't know how to adjust those damper (and that I should change Front & rear in together),

so I did contact Avo and they tell me " turn knob to full sift and the turn clockwise for 3-4 clicks, this should be good for basic road use", but I don't think it means that will replicate OEM damping ...

Any feed back on Avo damper adjustment ?

[saska]

my Lotus garage told me that he didn't know how to adjust those damper :shock: (and that I should change Front & rear in together),
so I did contact Avo and they tell me " turn knob to full sift and the turn clockwise for 3-4 clicks, this should be good for basic road use", but I don't think it means that will replicate OEM damping ... :?

Axel there are 2 separate issues with aftermarket dampers:
1. Ride height -- this is controlled by where the lower spring seat is on the damper in relation to the lower suspension. The higher up the damper the lower spring seat is the higher the car will ride for any given spring.
So the OEM spring seat on fronts is 125mm above the upper yoke mounting hole ( see first page of this thread for photo)
Rear: lower spring seat on damper to centre of lower eye: 168mm

2. The bump/rebound characteristics (curves) of the damper -- this is what is changed by the knob on the AVO's. The problem with AVO's or any other aftermarket damper is that no one knows which setting on the knob replicates OEM.
That's where I came in and am working with Pro-Tech to try to get a damper that replicates the OEM charecteristics as closely as possible. It is still adjustable stiffer or softer but at least you know where you're starting from.

State of play on dampers is Kevin @ Pro-Tech wanted additional measurements since he's taken on board the piston rod travel difference between front and rear (75mm vs 90mm). The drawings were done this past weekend and he should have them today or tomorrow.

[Axel-F]

Thank's, that was my understanding of this thread,
- possible toreplicate OEM ride height,
- no information to replicate OEM damper properties with AVO.

So I am very interested with any user feed back on those protec, to decide what to do with the AVO I have alredy bought...

[knoxmotorsports]

interesting that the euro springs are very close to the US springs. we measured a set with 25k miles on them at 310#/in front and 148#/in rear. very close.

I also have US damper valving specs if anyone is interested. They aren't published as in the same variables as Bilstein do theirs (.52m/sec shock acceleration), but good enough for a comparo, methinks.

[RayD]

Thank you for that Billy,

Did you get the physical dimensions; it would be helpful to see how they differ in length, with regard to the altered ride height.

Ray

[knoxmotorsports]

US Springs:

Front orange yellow blue (or is it blue yellow orange)
310# 4-3/8"diameter coil, free length 10.75" 8 coils, ends ground flat, wire diameter .5455"

Rear orange yellow red (red yellow orange)
148# 4-1/8" diameter coil, free length 9.5" 7 coils, ends ground flat, wire diameter .4235"

US front shocks appear to have 3-1/8" bump travel until contact with bump rubber.
US rear shocks appear to have 3-1/2" bump travel until contact with bump rubber.

[RayD]

Thanks Billy,


Ray

[RayD]

We were trying to get to the bottom of the US ride hieght when ...

On the front damper - Part Number B100C6029H the distance from the very top of the clamp bracket to the underside of the spring seat is 4.5" (114.3mm).

It could be that the US spec spring seats are welded in a higher position compared to the UK version.

Could someone check the UK version ... I realise there's a measurement is on the thread but to a slightly different point.

B100C6029H - 4.5 -114.3.jpg

Ray

[saska]

We were trying to get to the bottom of the US ride hieght when ...

On the front damper - Part Number B100C6029H the distance from the very top of the clamp bracket to the underside of the spring seat is 4.5" (114.3mm).
It could be that the US spec spring seats are welded in a higher position compared to the UK version.

Could someone check the UK version ... I realise there's a measurement is on the thread but to a slightly different point.

I make the red ? in the photo 113mm (rough with a tape measure) on a new F100C6015S (UK damper)

[RayD]

Thanks Tony,

Ray

[knoxmotorsports]

i suppose 1mm is close enough to be considered sampling error/conversion error between us and uk measurements.

mine was also done with a tape measure.

[saska]

Various people have asked me privately on the state of play, so it is only fair to post to the group at large:
The springs were sorted by Turtons in very short order -- I think we can buy from them with confidence that the parts will meet specification.
The dampers are a different matter. When I researched initially it became fairly clear that the Protech dampers were the one to go for over the Gaz, AVO options.
The situation with Protech is that they've dyno'd and got graphs for the OEM front & rears I sent them but in spite of calling them every week/couple of weeks I've been unable to get them to graph an equivalent Protech damper. Kevin@Protech appears to be keen to do this but hasn't so far. It may well be because I've insisted on exact dimensions for piston travel, damper body length, bump stops, etc. In other words we are asking for very specific requirements for not many units on the order, meaning it has a low priority as far as Protech is concerned.
So what to do.
I'd considered contacting AVO to see if they'd dyno a set of OEM dampers and tell us which setting on the PH747/8 is closest. Problem is the AVOs are steel so they rot and I think the Protech Aluminium damper is a better unit.
Some notes that I've picked up along the way: The Protech dampers SJs are doing are dimensionally different from OEM in terms of piston travel -- it's much longer. Think the distance to bump stops may also be different.
That doesn't mean they don't work in practice, it means they are dimensionally different.

Think I'll persist with Protech a little longer as I still think that this is the best OEM replacement solution unless someone has a better idea.

[RayD]

I think you do right Tony, particularly as Kevin seems helpful from what you have said in the past.

Ray

[BFG in the BRG]

Thanks for the update and your efforts - I guess we'll get here in the end.

I'm in no rush for these - they won't go on until next winter/spring and I need to save up anyway.

Kind regards

BFG

[Denny]

I'm happy to wait. The Protech dampers do appear to be the best option. Thanks for all your efforts.