Alloy vs Steel shocks

[TrevS]

Hi all

I am just about to order my suspension parts from Tornado and one of the options I have is to replace the standard steel shock absorbers with aluminium versions.

It seems the main benefit of these is a reduction in weight so can anyone tell if and how the reduced weight will help with cars handling, ride etc, are there any other benefits of alloy shocks and would any other owners recommend these over the standard units.

 

[Rich Roy]

Is this weight savings for racing? For street use my question is durability/strength like when you dodge that pot hole but still catch the edge. "Bang" and the top of the main shaft snaps off. The body of the cylinder made of alumium verses steel would not make any difference. What about cost and avalibilty over the standard shock. I just waited 100 days to get a rear Spax shock from England to Spokane, USA. About $240.00 US dollars (multi-adjustable Spax coil over CAV GT40)

 

[Tim Kay]

Trev,

I would say it's nice to have the aluminum shock for not only lightness but latest valve technology is applied. Also, if they are adjustable then a huge plus. I switched my old shocks for QA1 aluminum body dual adjust and it made a huge difference in all aspects, mainly the ability to adjust for road and/or track conditions.

 

[TrevS]

Is this weight savings for racing? For street use my question is durability/strength like when you dodge that pot hole but still catch the edge. "Bang" and the top of the main shaft snaps off. The body of the cylinder made of alumium verses steel would not make any difference. What about cost and avalibilty over the standard shock. I just waited 100 days to get a rear Spax shock from England to Spokane, USA. About $240.00 US dollars (multi-adjustable Spax coil over CAV GT40)

The car is going to be a road car but so far I've had every available option for the car just in case I do decide to take it on track days etc and also I want the car to be as good as it can. The aluminium shocks are an extra £300 over the standard steel versions. The Tornado website also says they retain a steel body for strength. The cost isn't an issue but I just wondered what the advantages are with the reduced weight. Does it improve handling due to the reduced unsprung weight?

Trev

 

[TrevS]

Trev,

I would say it's nice to have the aluminum shock for not only lightness but latest valve technology is applied. Also, if they are adjustable then a huge plus. I switched my old shocks for QA1 aluminum body dual adjust and it made a huge difference in all aspects, mainly the ability to adjust for road and/or track conditions.

Thanks for the info, very helpful. Looking more likely that the aluminium versions are the ones to go for

Trev

 

[Kevin Box]

Diverting slightly from your original post.
I would like to hear from anyone on the best method of determining what your shock length should be.

By this I mean;-

For compressed length : Is it the shock length when you have reached your minimum ground clearance taking into account the bump stop in the shock???

For expanded length: How much droop should you allow or should you just use the length at which the chassis constrains any downward movement of the suspension arms.

thanks in advance

Kevin B

 

[JimmyMac]

The GT40 used Koni 8211 steel bodied double adjustable shocks.
An alloy version with identical mechanical internals is Koni part number 8212.

The shell weights are as follows :

Steel 8211 body = 2 lb - 0 oz.
Alloy 8212 body = 0 lb - 13 oz.
Weight variance = 1 lb - 3 oz. (per shock)

So frankly I think choosing an alloy road car damper for an 19 oz. weight saving per corner is less critical for performance and more to do with appearance.

 

[DARREN]

Multiple reasons that i sell aluminium shocks only:-

1. Steel bodied cheap shocks like the Gaz, Spax etc don't tend to last long before rust is present and this looks bad and also siezes up the threads.

2. Weight

3. Heat transfer. Shocks worked hard produce a lot of heat and you need to get shot of that to keep the oil viscosity at the point where the proper damping is achieved. Twin tube dampers have very small pistons and therefore work their oil harder producing more heat, so the higher heat transfer rate of aluminium is an advantage.

Other things to consider. Aluminium options on Gaz (Tornado) shocks should not be £300 extra. Just take a look at the various people offering Gaz and other leading aluminium bodied shocks. The price difference is less than that.

The Gaz is a copy of the Spax and is a twin tube style damper, the QA1 whilst being a budget shock is a mono tube damper and has considerably better valving and performance.

The Protech shock is another Spax copy but it has had the benefit of a redesigned adjustment mechanism which gives much better feel and positive adjustment increments. A set of Protechs with springs to fit a Tornado - £480 direct from Protech and less from dealers like myself. So don't pay more than that for an older design.

You may have issues with bending rods and leaking seals in all shocks during accidents and high mileage etc, but, you'll very rarely see a bent or broken shock body whether it's aluminium or steel. Aluminium shocks still use a steel rod.

I spent many years designing shock absorbers for racing and OE applications. All my designs were mono-tube because of the performance requirements, but, i spent a lot of time reviewing the designs and performance of twin tube dampers in the lower end of the market. I worked closely with Nitron who developed the design that Protech uses. If you can afford it buy a twin tube racing style damper (prices from around £650 per shock), otherwise i came to the conclsion that the Protech aluminium shock has the most advantages over the other budget shocks.

D.

 

[Mike Pass]

Not all the parts of the shock absorber (damper) move with the suspension arms and upright. The mass of these moving parts is very small and insignificant compared to the mass of the upright, wheel and tyre. Obviously the lower the unsprung mass the more easily the tyre will be able to follow the undulations in the road.
The reduction in the overall mass of the vehicle will be even more insignificant.
Unless you are racing and using slicks and mag wheels the difference isn't noticeable. However the avoidance of rust in steel items is a benefit with alloy shocks.
Cheers
Mike

 

[TrevS]

Thanks for all the input guys. It seems to me that alloy shocks are the way to go. Not so much for the performance benefits but certainly for the added benefit of them not rusting.

I've also been looking at some other options for shocks, particularly 2 way adjustable shocks with remote reservoirs to allow more control over the suspension setup. As the car is going to be used for road and the odd track day do you think having more adjust-ability in the suspension is a good thing?

Trev

 

[Mike Pass]

Very often too much adjustability gets confusing. I once had an F3000 car with Koni 3 way adjustables which I could never get a handle on as to what the best settings were. Unless you are a suspension guru or Ayrton Senna the simpler the better, especially for road use as roads are too variable to get a setting which fits all circumstances. I use the Protech shocks which give good results for the money.
Get a F/R spring stiffness which gives a good cornering balance with the anti roll (sway) bars disconnected then reconnect the bars and adjust the F/R roll stiffness to give a good balance. Then set the shocks stiffness to give a good but controlled ride and good turn in. This will give you a good baseline to work from. A good road setup will be too soft on track and vice versa. Set it up for what you do most of.
I use a firm but still compliant road set up and tweak it up a couple of clicks on the shocks for track days. 500 miles of travelling on our beautifully maintained "roads" in a bone shaker will spoil your day.
Cheers
Mike

 

[Bob Putnam]

Aluminum might be lighter (and their design might be more sophisticated, but I don't see much evidence that steel shocks "rust". 99+% of road cars have steel dampers which must endure much worse conditions than your typical race car or GT replica, and they do just fine. Some wear out faster than others, but that's mostly due to quality of the valves and shafts. The same stuff that an aluminum-bodied damper would have.

 

[Mike Pass]

Most road shocks don't have the threaded outside for the spring platforms that adjustable shocks have. It doesn't matter if the outside of a non adjustable shock rusts. However if the threads on the adjustable rust then it won't be possible to adjust or remove the spring or bump stop.
Cheers
Mike

 

[Mark]

Steel Spax came off my car. Rusted threads big time and how heavy? Nasty. I haven't 'scientifically' compared the weight, but it certainly 'feels' like two Penske's weigh less than one Spax.

I really would recommend Alloy from the get-go. Sounds like you plan on keeping the car for some time and may get hooked on track time once you get started. Just my opinion, but get it right from the outset, otherwise you're wasting money later on. (I know alot about wasting money!)

 

[TrevS]

Steel Spax came off my car. Rusted threads big time and how heavy? Nasty. I haven't 'scientifically' compared the weight, but it certainly 'feels' like two Penske's weigh less than one Spax.

I really would recommend Alloy from the get-go. Sounds like you plan on keeping the car for some time and may get hooked on track time once you get started. Just my opinion, but get it right from the outset, otherwise you're wasting money later on. (I know alot about wasting money!)

Agreed Alloy it is. Just need to decide if I want a 1 or 2 way adjustable setup now.

Trev

 

[Mark]

2-Way would be ideal for you I think, based upon you desription of future use. 4-way is too technical for anyone who doesn't live at the track. 3-Way maybe the same (although I have 3 way! and will probably blow a brain fuse figuring it out!). Simple bump and rebound is not too complex to get your head around I reckon and not terribly more expensive than single adjust.

 

[Jack]

For what it's worth, I prefer 2-way adjustment. Simple and easy. I also like the feel of slightly softer springs and stiffer shock settings to go along with that (mainly for street).

 

[TrevS]

Thanks guys

I do very much like the sounds of the 2 way adjustable shocks but I was reading on one manufacturers website that the 2 ways they offer will most likely compromise some road comfort. Do you think this would be an issue for the odd trips to Le Mans etc? I think I can live with a firm ride but I think it could wear off quite quickly on a long journey if it was back breaking

Trev

 

[Tim Kay]

Trev, just go with a softer spring rate for road use if you're concerned about long trips and getting there with your spine still intact!

 

[Mark]

Agree with Tim.

I don't believe any car like this can be all things at once and do both well. Have softer springs for the road and harder for track. They can be swapped out pretty quickly once at an event.