Monotube Vs twin-tube struts

[shift_rook]

after having a few messages from people with questions about suspension tech, i've decided to make a dedicated thread, any questions feel free to ask and i will try and reply to the best of my ability.

Differences between an inverted monotube strut and twin-tube strut.
Usually the damper body sits on the moving suspension components or the unsprung mass and the heavier this mass is, the less the wheel can follow imperfections in the road surface. A damper can be sometimes 4kg which is a lot of weight to be moving with the wheel/brake package. With inverted monotube the main weight of the damper is mounted to the strut tower and only the piston rod moves up and down with the suspension, thus eliminating a lot of weight hence better wheel control. Therefore the best for(with the correct valving) performance driving. Aswel as the unsprung mass benefit, the body itself, the bilstein being 40mm OD versus a twin tube rod OD being 20-22mm. The 40mm inverted strut has 3x or more the surface area with the guide bearing, which supports the side loads, therefore giving much better long term durability for these components(especially when running negative offset wheels).

Monotube & Twin-tube pros & cons

From my experience it all depends on piston design and how that piston is tuned. You can find some very reasonable twin-tube shocks, just like you can find some absolutely terrible monotubes. Also keep in mind that twin-tubes have some drawbacks, they retain more heat than a monotube without the pressure on the oil column which creates cavitation (http://en.wikipedia.org/wiki/Cavitation). They can however offer much higher compression forces for low vehicles, due to not relying on the gas pressure from the dividing piston in the monotube assembly.

Any questions or articles i write up i will edit this original post, cheers guys:D

[Sam-Q]

nice work, I have eddited the title thought to be more specific, that is unless you want to add other information

[shift_rook]

yeah that's what i'm planning, when someone has something to know instead of getting 20 different opinions i'll try and give as close to fact answer instead of just going what others have said. maybe something like suspension tech q&a

[Nicko]

When I get my internet back on at home, we will invest some time into making a proper FAQ / WIKI type thing again

[McLEVIN]

I've have read up on this briefly, and found a general consensus that mono is good for track but twin tube is better for street use. Would this be accurate? Or would the difference be very minor?

[ke_70]

any information on valving to suit setups ect.

eg corner weights, spring rates, ect

[shift_rook]

Mclevin i answered your question partly, clay i'll do something in dpeth tomorrow night :)

[Skylar]

Text books will say set the springs to give a 2hz free oscillation(non-aero cars) or 3deg/g and damp for somewhere inbetween like 0.5 and 0.75 damping coefficient in the low speed region and go to much less for high speed stuff.

Whatever that ends up in corolla language, I don't remember.

I'm interested in hearing your input shifty.

[shift_rook]

firstly just clearing up with you this is my input, however i get the old man to go over everything and make sure i'm not just spinning shit, this is his opinion to your input skylar
"with all the cars that i've tuned over the last 15 years, this has never been a concern or a rule that is used during vehicle development. The only worry for a damper engineer is to build a durable valve code, that will last the warranty period and that performs better than the previous model, whether the customer wants better ride or handling. I have worked with many engineers that have a lot of text book theory, but it rarely translates to making the car feel good.

[Skylar]

I understand the component, be it engine/turbo set up/cams/springs/ARB's/dampers, will usually need several iterations to get it working optimal but how do you arrive at the starting point?

You use a shock dyno to tune dampers first then go off driving feel?

[shift_rook]

yeah that's right, after several years i guess you get the knack for just knowing a reasonable base code. then it's off for driving and evaluation to make further improvements.