Replacing Dampers With Coilovers...?

[rallyeash 155]

Hi all,

 

I'm just bouncing an idea around and debating if there would be much benefit...

 

So I had a 1.9 beam on my 205 recently, 23mm TB's, 27 Arb etc etc which I sold to go down the coilover route from Colin.

 

However yesterday I was at Castle Combe watching the Welsh Saloon Car series which looks like would be a great series, some interesting cars and my 205 could be eligible however you are only allowed a rear turret on Mk1/2 Escort's and Minis. How unfair haha.

 

I've got a standard 205 beam which was going to be fitted to my 205 and originally have Colin's vertical coilovers but due to standard pick up points required this isn't an option.

 

So rather than banging a large set of torsion bars into the beam like I used to had what's the thoughts on running a replacement coilover in probably 1.9id as a direct replacement to a conventional damper.

Such as https://www.merlinmotorsport.co.uk/p/avo-coil-over-damper-aluminium-body-with-poly-bush-mount-for-1-9-inch-springs-apa

 

I haven't worked out spring rates but I think the damper length would probably be 13' open 9' closed, guessing a spring rate of possibly 100lb to work in conjunction with a standard GTI anti roll bar.

 

Opinions? I can't see how it won't be an improvement if done right, also if I don't get on with it a can just swap for a normal damper.

 

Ash

[Tom Fenton 1,541]

Work out what spring rate you would need in order to achieve a sensible wheel rate, plus the movement you would (nt) get, and then you'll see why its not a great idea. Ratio on the trailing arm to damper mount movement is something like 3:1 I think. If it was easily workable solution then I am sure Mr Satchell wouldn't have spent the time and effort on the fancy pushrod rear setup, and countless others wouldn't have turretted cars.

[rallyeash 155]

Yes I have thought of that and I'm not trying to compete against the 1/1 turret option that Colin offers which isn't allowed in regs anyhow.

 

I'm trying to work out if running standard bars with a lightly sprung coilover would be better than 23mm torsion bars and a gaz damper for example. Yeah I believe a 30mm wheel movement is roughly a 10mm damper movement.

 

Colin has done rear coilover dampers before on Dixons 306 to fit inside regs with a lower shock mount.

 

 

 

 

[welshpug 1,656]

I think I'd have a go at replicating the pushrod setup theyve done for the 106, I'd have a chat with Colin or Dave about it, it looks like it would bolt up to the shell in a very similar manner.

 

 

Which events/regs are you planning on doing?

[rallyeash 155]

I've spoke to Colin about him doing a pushrod setup before and he didn't feel it was really worth doing as a bolt on kit. I'm sure the car could go down there and it be done but I need to be careful with monies nowadays due to having my own business etc.

 

So do you think a coilover damper and small TB setup would work less efficient than larger bars and damper. A standard position coilover would actually be cheaper than buying larger torsion bars again.

[Miles 331 1 Cars]

Very similar to this set up,

 

which my mate runs on his 205,

[rallyeash 155]

Does that run standard damper location miles?

 

How does he get on with it?

[Miles 331 1 Cars]

Yep bog std damper location, He likes it as it is but it get's driven a couple of times a year, I think it's a bit stiff in theory but I've not driven it to a inch of it's life so cannot say, But the design comes from before my day

[rallyeash 155]

Hmm ok. Any idea on spring rates of the coils and torsion bars?

[Miles 331 1 Cars]

He's got 25mm bar's, going by the dia of the springs I'd say allot as there was no markings on them

[rallyeash 155]

A bit of a search shows spring rates are approx

 

19mm bars 110lbft

23mm bars 235lbft

25mm bars 330lbft

 

I actually found my 23mm bars a little stiff, I'm not sure how a 19mm bar and a 100lbft coil spring would equate too at the wheel?

[allanallen 528 2 Cars]

IMO the springs/torsion bars aren't really the problem, it's the damper or rather the piss poor ratio. Fitting a coilover in the standard position is absolutely fine and a good way to fine tune your spring rates but it's only ever going to work as well as the damper you fit.

I'm not really sure what you're trying to achieve ash? Just saving some money on buying bigger bars?

[rallyeash 155]

Yeah I guess that's why on the above photos the lower shock mount is moved to give a better ratio.

 

To be honest it's more looking at the theory if a coil and small torsion bar setup would give a better ride, any more grip and better dampened than a thick set of bars.

[petert 585]

A bit of a search shows spring rates are approx

 

19mm bars 110lbft

23mm bars 235lbft

25mm bars 330lbft

 

I actually found my 23mm bars a little stiff, I'm not sure how a 19mm bar and a 100lbft coil spring would equate too at the wheel?

You can never be too stiff on the rear if on tarmac. Especially with slicks or AO50's. If the ratio is 3:1, then to get 500lbs of wheel rate with 23mm bars, wouldn't you need approx. 795lb coil over springs?

Edited April 7, 2015 by petert

[rallyeash 155]

Is the formula just 3-1 then?

So a 600lb spring is 200lb at the wheel?

[welshpug 1,656]

if you stick it where the original damper is, pretty much yes

[petert 585]

Is the formula just 3-1 then?

So a 600lb spring is 200lb at the wheel?

 

If Tom's 3:1 ratio is correct, then yes. Thus 23mm torsion bars + 600lb coil over = 235 + 200

 

Less than ideal in terms of adding mass, but cheaper then turrets. My car is turreted, but I can easily revert to original if required.

[Tom Fenton 1,541]

Don't quote me at 3:1, thats a educated guess.

 

Also don't forget that due to the arc the lower damper mount moves in, the rate is constantly changing throughout the arc of movement anyway.

[rallyeash 155]

I've heard 3-1 before, I could bolt them into standard position and see how it fairs with the potential of moving the lower mounting point in due course.

[rallyeash 155]

[rallyeash 155]

Torsion bar fitted back in, shock gap set to 300mm and 13-9' 1.9 dia coilovers fitted on 225lb springs.

 

Track day at Angelsey next weekend so will see how it fairs. I can return to a set of Gaz dampers on the day if I wish so just be a standard 1.9 beam with a 24mm ARB.

 

Think my long term plan is to move the lower damper mount, run base model torsion bars and a higher spring rate but we'll see!

 

Edited April 10, 2015 by rallyeash

[camgti 56]

Nice work Ash. Good on you for having a crack! Will be intereating to see how you think it gets on.

 

A few guys here a running a similar setup with base model bars etc.

 

Now finish that 309!

[Goliath 94]

I'm a bit late to the thread but I spoke at some length with colin about this several months ago as my penske rear shocks have spring seats on them and I thought of doing the same as you but he advised me that (as Tom says) it is a 3:1 ratio in the standard mounting positions and that the shock wouldn't work correctly like that, despite being a decent shock.

[calvinhorse 870]

No messin!

 

Just a thought- the pressed steal legs that the damper is mounted to is only enough to support the damping side of the suspension so asking it to take the added force of the spring aswell is maybe a bit much! It just wants beefing up a bit.

Same goes for the boot floor in that area

[rallyeash 155]

I'm a bit late to the thread but I spoke at some length with colin about this several months ago as my penske rear shocks have spring seats on them and I thought of doing the same as you but he advised me that (as Tom says) it is a 3:1 ratio in the standard mounting positions and that the shock wouldn't work correctly like that, despite being a decent shock.

Yeah I do get that, but it's no worse than running a standard damper and thick bars, I want to see how it feels like this then think about moving the lower position to get a better ratio.