Suspension setup for heavier engines?

[Ian S]

heavier engine but don't want my fillings knocking out with every slight road imperfection.

You could probably use 350lb springs with that weight. But you'd need custom valves shocks. You need the rebound setting more resistant, or it'll bounce due to the extra spring force which needs to be a controlled release of the spring compression. And the bump setting needs to be softer as you have harder springs and you'd don't need the shocks also preventing the wheels from rising over bumps.

Not the cheapest but probably the easiest to get right would be for you to get decent shocks with separate adjustment for bump and rebound. 'Coilover' springs are (were?) relatively cheap and easy to swap until you find the optimum spring rating and height for your vehicles mass and configuration.

To get a softer ride, maybe use tyres with taller side walls?

[Matt Cole]

Ive moved and started this discussion as i think its relevant to all that have engine conversions.

[Matt Cole]

You could probably use 350lb springs with that weight. But you'd need custom valves shocks. You need the rebound setting more resistant, or it'll bounce due to the extra spring force which needs to be a controlled release of the spring compression. And the bump setting needs to be softer as you have harder springs and you'd don't need the shocks also preventing the wheels from rising over bumps.

Not the cheapest but probably the easiest to get right would be for you to get decent shocks with separate adjustment for bump and rebound. 'Coilover' springs are (were?) relatively cheap and easy to swap until you find the optimum spring rating and height for your vehicles mass and configuration.

To get a softer ride, maybe use tyres with taller side walls?

Thanks Ian. Good starting information. So my situation is that i have the megane 225 engine, NDO gearbox, big exhaust manifold and heavy turbo! Great for getting the power down, but isnt probably the best setup for turning corners. So, i want to use this car on the road, maybe the odd track day, but mainly driving around the god awful roads we have here in the UK.

I do not want coilovers! I think they are far too unforgiving for my requirements. What i do have though is 3 sets of front shockers to choose from:-

Koni adjustables Ph2
Spax adjustables Ph2
Standard decarbon Ph2

I am hoping to use one of the above matched to a set of springs that lower the car no more than 35mm. Im using 16" wheels with 195/40/16 size tyres. I may drop to 15's if it would help absorb the road surfaces.

So what to do? Could i use any of the above shockers and get some springs rated at 350lb/"? Would i have to get the shocks re-valved?

[Ian S]

'Coil overs' are as hard or soft as you want them to be. Just turn the adjustment knobs.

None of those standard shocks will do unless you get them custom valved. That might be possible with the Konis.

You'll have some difficulty getting the height right. It's will likely require at least two sets of custom made springs that were wrong, until you home in on what you're after. Not so much of a problem with off the shelf 'coil over' springs, especially if the shocks are height adjustable.

You might favour 275lb/inch springs or 400lb/inch. You're pioneering in uncharted territory.

[Matt Cole]

Well looks like I'm going for a set of Gaz adjustable with 350lb springs. Hopefully it gives a forgiving ride on the road when adjusted accordingly.

[Ian S]

Were Gaz ever know for a forgiving ride?

Avo, same make I think, shockingly hard, viscera shaking, back hurting hard.

You can(could anyway) get Konis revalved to work with 300lb springs at least.

If you got the more expensive KW, they have separate bump and rebound adjustment so you possibly could dial them in yourself.

[Matt Cole]

Cheers Ian. Suspension is a big investment and I don't want to shell out and hate driving the car from the off!

[Matt Cole]

Ok, as an update, ive now purchased a set of what appears to be Avo front coilovers. Ill use the with my Gaz rear adjustable dampers. Front springs are i think 275lb. I'm running this setup with 172 hubs and big discs etc so unsprung weight will be greater. Next test will be to see what settings for the dampers.

[Matt Cole]

Ok as an update, all fitted. Took for a test drive today and all i can say is..............................not impressed!

The car 'bangs' over uneven road surface/holes. Its like its bottoming out or something. I've adjusted to max soft and max hard, and on hard it does resist the banging better than when on fully soft. Would stiffer springs be the answer, or maybe increase the ride height to allow for greater shock travel? Springs could be going coil bound, i dont really know.

Its a shame as the rest of the hub conversion appears to be working ok.

[Matt Cole]

It appears coil bound quite possibly and very little travel left on the shock!!!



The springs are only about 7" long uncompressed. Maybe slightly shorter from memory.

[Matt Cole]

Looking on eBay I see a set of 8" long 350lb springs. The Avo shocks only have one adjustment facility. I'm not sure if it does bump and rebound proportionately, but that's what I have to work with for now.

Given the general consensus that 350lb seems to be a good starting point, I may opt for trying those?

[Matt Cole]

I've lifted he ride height an inch or so. Seemed a bit better but I still get the almighty thump when going over sharp deviations of road surface. I noticed after the test drive, the ride height had dropped/settled by 10mm. The springs could be a little tired.