Hey guys,
Have people here used Ron's coilover suspension? What's people's take on it for a fast road car?
I've only read good things about it overseas but would be good to get people's opinion here.
Thanks guys!
Here's the link if you want to check it out!
http://www.rsrshop.com/
I've not got any direct experience with the RSR set up, but when you learn some stuff about suspension the RSR stuff looks like a very big compromise that puts a lot of stress into the chassis.
The combined front spring rate alone is very high and in a relatively light car like a GTV or even the slightly heavier GTV6 would push the front suspension's natural frequency well over the 2Hz (probably over 2.2Hz). That sort of natural frequency (suspension stiffness) is the domain of dedicated track cars, running on atleast semi-slicks and more importantly, with a reinforced chassis.
The 30mm front anti-roll bar is 244% stiffer than the 75's 24mm bar.
And is 346% stiffer than the 22mm front bar.
Huge anti-roll bars on independant suspension reduces the independance of the suspension.
The rear spring rates are just as mad in the natural frequency that they give the car and the rear ant-roll bar is even more massive in its percentage gain. 350% stiffer than a 19mm bar.
Now all of this is just my opinion, but the RSR stuff never addresses the Alfa TA chassis biggest issue of poor front suspension geometry and tries to brute force the chassis into submission. All of that brute force gets fed into what is not only an old chassis that has more than likely been battered by use, but a chassis that was not particularly rigid when they were first built.
Jim K on GTV6.com once made some rather interesting observations about how effective a simple bolt in roll cage was for the feel and lap time of his 75 road car.
You have quite the wealth of mathematical knowledge there Duke!
Definitely makes sense though. Even if thought the 30mm bars were quite large, especially without reinforcing the chassis.
Roll bars aside, I've heard that the coilover suspension can be a better ride than bigger torsion bars (say 28mm) with Koni Shocks whilst also providing better handling providing adjustments in the dampers are correct for the road.
I haven't got experience with this so I'm not going what I said is correct, just what I've heard/read.
Reason I ask is that I'm in 2 thoughts with my suspension:
1. Go through Performatek and get the 27mm torsion bars, and the recommended other bits to go with it (ie Koni yellows all round, castor ball joint conversion, SZ de dion bush conversion, slightly bigger sway bars front and rear, reinforcement plates where the front sway bars mount, lowered Springs at rear and upgraded watts linkage if required)
Or 2. Go through either RSR or Intrax and go down the coilover method (Intrax recommended me to go down the path of just coilover front and rear with dampers pre-adjusted from their factory without adding bigger roll bars or upgraded watts linkages as they are confident their system will eliminate a lot of roll and that this is meant to be a fast road car).
Again the whole world of upgrading suspension is still relatively new to me so anyone's recommendation of what they have done is more than welcome!
I do plan on installing a half cage in the car so hopefully that can help with the rigity of the body.
Here's the link for a company called alfa 9 supply, also supply the intrax suspension:
http://www.alfa9supply.com/transaxle-alfa-parts/
Read up on the ARC (anti roll control) system, seems like a quite advanced system!
I've been recommended the IK2-V2 system in conjuction with the ARC system, for a road car they say to remove my roll bars all together!
Quote from: gtv6sv on September 07, 2016, 04:15:43 PM
Roll bars aside, I've heard that the coilover suspension can be a better ride than bigger torsion bars (say 28mm) with Koni Shocks whilst also providing better handling providing adjustments in the dampers are correct for the road.
I haven't got experience with this so I'm not going what I said is correct, just what I've heard/read.
Reason I ask is that I'm in 2 thoughts with my suspension:
1. Go through Performatek and get the 27mm torsion bars, and the recommended other bits to go with it (ie Koni yellows all round, castor ball joint conversion, SZ de dion bush conversion, slightly bigger sway bars front and rear, reinforcement plates where the front sway bars mount, lowered Springs at rear and upgraded watts linkage if required)
Or 2. Go through either RSR or Intrax and go down the coilover method (Intrax recommended me to go down the path of just coilover front and rear with dampers pre-adjusted from their factory without adding bigger roll bars or upgraded watts linkages as they are confident their system will eliminate a lot of roll and that this is meant to be a fast road car).
Just for comparison sake and this is calculated for the short torsion bars, but an RSR front spring is 600lb/in. With a 22.8mm TB (standard 75 TB, 'cause that's what I should be working on............. ::) ) and that spring, the combined overal spring rate would be comparable a torsion bar about 31.2mm in diameter.
Interesting to see this picture. Notice the car has an upside down lower balljoint (to dramatically raise the front roll centre height and make the camber curve characteristics much more effective), with what an aftermarket forged aluminium lower control, what looks like a 105 upright arm and a bent steering arm to correct for bump steer.
Duk, you're all over the math! just out of curiosity, what spring rate would that equal to for a coil over only set up? Any idea what 29mm torsion bars would be equivalent to?
Definitely an interesting set up, looks quite serious!
I agree 105gta, your math work phenomenal!
I too would be interested to know the spring rate for a cool over only set up if you know?
A short 28.7mm torsion bar would be the increadably close to a 600lb/in spring mounted on the shock absorber.
Wheel rate would be 233lb/in.
Sorry for the imperial numbers, that's just what seam to work best for me.
The spring would be 107.37kg/cm.
The wheel rate would be 41.7kg/cm.
Thanks duk. I work in imperial most of the time myself. Do you happen to know what a 32mm torsion bar would equate to?
Standard (75) 22.8mm TB equal around 242lb/in.
27.3mm TB would be around 495lb/in.
28.7mm TB would be around 602lb/in.
30mm TB would be around 723lb/in.
32mm TB would be around 932lb/in.
Again, those are comparable for the short TBs.
Great info on all the statistics Duk, thanks for that!
I'll ask Ron on what he reckons of just having the coil overs and see what his response is and come back here.
I'm the meantime, Duk what do you recommend for suspension upgrades for a fast road car?
Anyone has experience of putting on the SZ De Dion bush onto a GTV/GTV6/75?
I have the dedion spherical bearing as well as rose jointed watts link, lowered roll Centre and 2' of neg camber. This was all done at once naturally so I can't say what had the most impact, I guess the roll Centre change but all together it sticks, and sticks good. Can highly recommend it!
Gtv6sv, in response to your original questions, what are your goals/use for the car but just as important what else have you done to improve it? Or plan to do. For example wheel and tyre size have an impact on suspension setup.
Quote from: gtv6sv on September 09, 2016, 06:28:04 PM
I'm the meantime, Duk what do you recommend for suspension upgrades for a fast road car?
Front suspension geometry fix. Easiest is something like the Pace Engineering top balljoints, but you still need a bumpsteer solution after that. It's not that hard to sort out.
Torsion bars either 27.3mm and 28.7mm, but more than likely the 27.3mm. Or adding 250lb/in spring to the damper to get that. Or a 360lb/in spring to get you closer to the 28.7mm bars. But you can't get an off the shelf 360lb/in spring so either a 350 or a 375 spring........... Not much difference either way.
Rear springs are a bit harder because the motion ratio of the rear springs is much higher than any added front spring/damper motion ratio. A 175lb/in spring is probably a good start, but maybe a touch soft. A 200lb/in spring is getting up there (in natural frequency), tho.
Anti roll bars would be something like an adjustable 27mm front bar. And either modify the rear bar so it can be adjustable or just leave it standard. Being able to tweak the rear bar would be helpful if you went with 200lb rear springs and wanted to soften the rear bar a touch.
But dampers (shock absorbers......... ) is the biggest issue and 1 I only have opinions on and no real experience to back it up.
Dampers is where, from peoples comments on the ride quality, the Intrax/RSR set up sh!ts on everyone else!
And the ability for them to be able to have all of that (excessive) spring rates and still give a decent ride quality comes down to having digressive style dampers. That and the fact that the chassis is flexing a lot...............
But properly set up digressive dampers give the best results.
And here's where I end up standing alone (so to speak) in that most people just say use Koni's and have them revalved to suit, I say Koni's are a linear valve damper and will always be compromised in their ability to control the car and spring(s) and provide over all decent ride quality.
Bistein make digressive valve dampers (NOTE: I'm not talking about the off the shelf Bilstein dampers that you buy for the Alfa's, they are linear valve dampers), but I don't know enough about what ones to use or how to assemble a shim stack to say "For 'X' torsion bars in a V6 Thingy-bob, use Bilstein 6035s at the front and 5030s in the rear.................".
So geometry, with bumpsteer correction. Fairly easy, and in my opinion a must.
Spring rates for the lighter GTV6 (rather than the havier 75 3 ltre that all of my number crunching has been based on), I'd look at the 27.3mm TB (or standard bars with a 250lb/in additional coil spring) and 175lb/in rear springs.
27mm adjustable front antiroll bar and probably just a standard rear bar.
Dampers/shock absorbers..................... That's the hard part. Off the shelf Koni adjustables will work. Revalved ones will work better again, but I still believe that properly shimmed Bilstein digressive valve dampers would give the best end result.
I have it. I love it.
Reality check: where can you find better for the outlay?
Are you driving a Tarmac rally car or competing at multiple race tracks with a race car?
If so, a bespoke coil over setup is what you want, with adjustable bump and rebound and you're best off calling Heasman's in Sydney to have some Bilsteins built for you.
Ron Simons ran a bunch of 75s at the Nordschleife and this was the kit he developed for them, before offering it for sale- this isn't the smoothest track, from experience, and the karrousel is downright bumpy.
If you're a weekend warrior/occasional track day guy, there is nothing that comes close to the RS setup- everything clears the UCA and they don't crash over bumps anywhere near as badly as big torsion bars do.
Yes, the major criticism with the RS kit is the short(ish) stroke of the kit, but you tell me one thing about these cars that isn't a compromise to begin with?
Combined with Vin Sharp's knuckle riser mod (because upside down ball joint is probably best left to the racers), the car handles ridiculously well.
I will be looking to seam weld some engine bay bits when my car goes in for panting,
Duk, what's your setup on your car?
Quote from: julianB on September 12, 2016, 03:32:17 PM
they don't crash over bumps anywhere near as badly as big torsion bars do.
This is a function of the type of damper used, because at the end of the day a spring is a spring (maybe with the exception of air bags).
I know that some people say you leave the main coil spring floating to help get a better ride, but there is no way that should be done.
Quote from: julianB on September 12, 2016, 03:32:17 PMDuk, what's your setup on your car?
My car has been off the road for a million years now.............. :-[
Before I turned it into a shed orniment it had a very mild but effective set up. Mild because I still needed to do a lot of learning but effective because it made very big improvements to a car I was initially very disappointed by.
So my 75 Potenziata had Pace Engineering top balljoints/knuckle risers, a pissy little 105lb/in additional spring (like I said, I still needed to learn a lot more) over Koni adjustables, with King springs lowered rear springs (of what ever rate they were).
What impressed me was the fact that it went from having a very lethargic turn in, with lots of understeer to having a great turn in and much, much more front end grip.
The thing still had a fare bit of body roll, but the antiroll bars were standard, the guestimate spring rates were way to low (but still reprisented a decent upgrade over standard) and the Koni's lack enough low speed bump damping to really help with weight transfer type body movements (before they then go on to have too much high speed damping and become over damped).
As it sits in the shed now it has additional 375lb/in springs at the front, 175lb/in springs at the rear (but I think 200lb/in springs might be a better overal rate), the beginnings of a tubular front antiroll bar that should have a rate very similar to a solid 27mm bar (but weigh a lot less), bumpsteer correction to work with the Pace Engineering balljoints, 105 caster arm balljoints, seam welded inner box sections, a 4 point chassis brace and Series 6 Mazda RX7 16x8 wheels on hub adaptors.
The big want is to figure out Bilstein dampers. But I'm a stuborn prick and that would all be done by your's truly rather than pay someone else to do it.
Removing a lot of weight from the front of the car, especially the heavy impact absorping bumper bars and gas mounts, relocating the battery and maybe some carbon fibre body pannels are all on the 'to do' list.
Worse than all of that stuff written, Doctor Frankenstein lives inside my head................ :o
These days I dream of custom made longer suspension arms, Series 4/5 RX7 wheel hubs (in aluminium) and use the Series 6 RX7 wheels (+50 offset with these) without any hub adaptors/spacers, all to get the steering scrub radius a lot lower (which should allow me to use 225 wide tyres on the 8" wide rims rather than the 215/45 tyres only just fit in there with steering lock applied (high steering scrub radius).
There should be a nice reduction in unsprung mass from those mods should have an overal reduction in weight.
On top of that, I want to have dedicated coil springs (kinda must for custom made lower control arms), maybe even move the top damper mount outwards (to get the damper's motion ratio higher),.
And then create some modified spindles with upside down lower balljoints (I'd slightly shorten the lower section to give better wheel clearance). The required steering arm bending would mean the arms are a bit shorter and that would slightly quicken the steering. But on top of that, the ackerman angle of the steering arms would also be corrected (and it's not right in standard form)........................
??? ??? ??? ???
Sorry. :P
You're venturing into a realm of mods that is well past what most of us are capable of!!!
For what i wanted, and probably most of us (bolt-on mods with enough scope to adjust for how we like the car to behave), the RS kit is the best option.
I would advise people to contact Heasman if they want a more tailored option- Bilsteins are awesome, after all.
I'll illustrate my experience and then I'll bow out.
My car was a 2.0 that got a 12v V6 transplant.
16x7.5" wheels, 205/50/16 Bridgestone something or others.
It had Bilstein shocks, 105 castor rods, 1.5" lowered and 20% (from memory) stiffer rear springs from King.
Stock AR bars. Stock watts link, Poly dedion bush.
I've forgotten, but it may have kept (and may still have) the old 4cyl torsion bars in it. I did those mods 14 years ago and covered about 20,000kms on it.
It rode bumps beautifully, probably because the torsion bars were under-done for the V6.
It understeered on turn in, fell over on the front end mid corner and behaved itself on exit, putting the power down nicely and steering pretty well. If you entered a corner hot and either trail braked or lifted off, you'd end up rotating and needed to be prepared to catch it.
Obviously, the front end understeer was crap and no one would want that.
Now:
105 castor rods, stock AR bars and Poly de Dion bush.
Changed: RS kit (added to torsion bars), PACE knuckle risers.
17x7" Wheels and 215/45/17 Bridgestone and Goodyear something or others.
How it drives:
Night and day.
Turn in is sharp. The steering is telepathic. I look where I want to go and the car changes direction.
Small throttle changes adjust car attitude nicely and precisely.
The only area where the car is not as good as before is the way it ride bumps.
This is to be expected when you increase the spring rate.
I can't say how the kit goes without the knuckle risers, but what I can say is that with the two, I've shoved it up the inside of R32 GTRs, S15s, and Type R Integras on public roads where I shouldn't be doing that, with ease.
I was always told to "fine tune" the car with AR bars, so once my GTA swap is done and I have the car running on Semi-slick shod 156 superturismo rims, I'll sort that out when I get a little more track active.
It is very easy to look at a "desirable" engineering outcome and say that the kit is not ideal, but I stand my ground in saying it is the best option for an Alfetta/162 chassis in existence because you bolt it on and get a massive improvement.
I'd go so far as to say that after fitting a TS 4.1 box with a shimmed out LSD, this is the best mod you can do to the car!
Interesting discussion - I need to read more....
Off topic but thought I'd add my own experience with the whole TS box in 3.0 thing as it was right after breathing on the list of life priorities for me a few years back.
3 months and 7,000 kms in the Macedon ranges and I can say its not really worth the money nor effort. The car got fitted with my old now new TS box - fully rebuilt, 50% LSD, lightened clutch etc. I barely noticed it at first (to the point where I thought I'd put the wrong gearbox in the car) and only really feels different in 4th/5th on the road.
Doing it again I'd do the early Alfetta gear-set and 4.3 final drive then it might be worth it on the road. Track driving - not sure - I'll find out later this year hopefully, if I get my act together and lock myself in the shed a few nights a week.
Quote from: 105gta on September 09, 2016, 11:41:34 PM
Gtv6sv, in response to your original questions, what are your goals/use for the car but just as important what else have you done to improve it? Or plan to do. For example wheel and tyre size have an impact on suspension setup.
My goal is to have a quick road car which will see the occasional track day here and there.
Car will be sitting on 17 x 7 wheels(road), plan on doing Vin sharps upgrades and also adding the watts linkage upgrade. Now I'm just seeing if it's worth going the coil over set up or go the torsion bar way.
JulianB, how did you find installing the suspension? Any mods required? Do you find you get flex in the chassis from it? I take it it holds the road quite well😊?
I purchased the Watts linkage from Ron but I didn't realise it wasn't kinked on one of the arms, so it doesn't clear my exhaust- that's something I will need to deal with later on.
I also didn't fit the suspension- I don't have the room to be able to do stuff like that in my unit block. No mods required.
It handles brilliantly on my car. The change in direction is great. You can feel a bit of flex from time to time. And as I said earlier, the only criticism I have is the rather short stroke of the shock.
If I were to build another Alfetta, I would never even consider going to bigger torsion bars- it would be RS or Heasman's Bilstein setup. I can't see myself changing the suspension out to anything else.