Coilover suspension upgrade (BiTurbo)

Messages
198
Hello Everyone!

One of our latest R&D projects for classic BiTurbo's is a modular coil-over system
This has been in de pipeline for a few years, and we're now wrapping up final testing.
Our initial setup will be for 5 bolt, post 1988 cars, so Ghibli, 2.24v, 4.24v, Shamal, QP4.

We're finalizing Quattroporte IV at the moment, Coupe suspensions are done
4 bolt older Biturbo's, we do have a prototype but it's not a "plug and play" install so that's still under consideration as modifications will be needed.


Why?
All older Maserati's suffer from a number of suspension related issues, the aim here is to offer a comprehensive fix, upgrade and to ensure serviceability
Issue we aim to solve and improve on:

  • Overly soft and worn suspensions
  • Replacement of the front strut bushing (common issue, especially QPIV)
  • Reducing brake dive (heavily improve braking stability)
  • Reducing excessive suspension dive (Oil pans, sub-frames, front spoilers hitting pavement, speed bumps etc)
  • Camber-adjustment to improve front geometer
  • Better rear axle control, the improved damping control will allow much easier control over the rear end (for example high speed roundabouts)
  • Offering a sustainable source of replacement suspensions into the future
Brief overview of the technical features
  • 30 damping adjustments (soft to hard)
  • Full ride height adjustment (independent of spring preload!)
  • Full spring preload adjustment (separately form the ride height)
  • Serviceable top mounts with spherical bearings (versus OEM rubber bushes)
  • Full front camber adjustment (to ether correct camber gain from lowering or to further adjust, just like factory Ghibli Open Cup)
  • Modular layout (interchangeable springs allow for a endless range of spring rates)
  • Extra front wheel inward clearance
Real world results
We've to start with been doing in-depth testing on a standard 2.24V and comparing it to a factory Ghibli Open Cup car (which represents the factories end evolution of the platform)
The handling improvements are rather dramatic whilst still remaining comfortable.
High speed cornering has been improved greatly for example with mid corner bumps and off-camber turns, low speed (roundabout) tests are greatly improved and the rear axle being predicable when pushed.
Braking at any speed is now very stable no brake dive, it also allows a greater degree of mid corner braking.

That said I'd rather have customers who have tested the suspension here to post up there reviews, we've had a few local owners do test-drives here.
Fairly sure it won't take long for one or two of them to chime in



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minardirule

Member
Messages
185
This is really interesting, one of the things I was looking at to have done over winter was a suspension rebuild to try and improve the ride.

Have you tested this on a Spyder as yet?

Can it be set to work with the existing electronic damper controls in the car? I realise the factory set up doesn't make an enormous difference between settings but it does seem to help over rougher road surfaces in the Spyder and reduces roll in the hardest setting.
 
Messages
198
This is really interesting, one of the things I was looking at to have done over winter was a suspension rebuild to try and improve the ride.

Have you tested this on a Spyder as yet?

Can it be set to work with the existing electronic damper controls in the car? I realise the factory set up doesn't make an enormous difference between settings but it does seem to help over rougher road surfaces in the Spyder and reduces roll in the hardest setting.
It completely replaces the existing suspension, the suspension is 30 way adjustable. (manually)
That said the reduction in roll is already achieved by the damping and spring rates, the suspension travel control is also enormously improved (you're not bouncing up and down over rougher roads, hence saving the sump)

This will fit a Spyder as wel.
 

henris42

Junior Member
Messages
86
Hi, very interesting indeed! One thing related to this that I was also wondering, was if I could also add rear rollbar from Ghibli to the 2.24v. Has anyone tried that before?
 
Messages
198
Yes, but you need the one with a ranger diff.
I may I recall even have a shamal bar left here.

That said on a 2.24V the rear swaybar isn't really needed after coilovers, as the rear ends are fairly light we've managed to remove roll with the springs.
 

henris42

Junior Member
Messages
86
I guess I just feel bit naked without a rear swaybar...
Always have, with this car.
 

Maurizio

Junior Member
Messages
55
The coilover suspension upgrades looks absolutely brilliant! Maybe I should start saving some money...
@henris42 Yes, I have a sway bar in my 2.24v, taken from a Ghibli and it made a lot of difference, for the better.
I learned directly from Biturbo testers from the De Tomaso era, that it was something that they always asked for, but that De Tomaso refused, for reasons that are very difficult to fathom.
Here's my sway bar
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minardirule

Member
Messages
185
It completely replaces the existing suspension, the suspension is 30 way adjustable. (manually)
That said the reduction in roll is already achieved by the damping and spring rates, the suspension travel control is also enormously improved (you're not bouncing up and down over rougher roads, hence saving the sump)

This will fit a Spyder as wel.

I guess my main concern was if it's set up too stiffly it'll shake the Spyder to pieces! They're not exactly the stiffest body shell in the world.

Has anyone fitted this kit to a Spyder yet?
 

alpa

Member
Messages
169
Wow !
Finally there are REAL improvements for biturbo !
It's especially interesting for the front. rear is much easier to tune with the range of existing biT-GT-Cup-QP4 dumpers and springs.

I've got questions, forgive me if being too enthusiastic I did not pay attention to all said details:
  • is this compatible with both front and read stock springs ?
  • what are your springs ? (I have a pile of various springs).
  • are shocks some sort of inserts or is your strut a shock ?
  • are shock walls single or double layer (see the question above) ?
  • are the shocks gas ?
  • can the shock oil be replaced (serviced) ?
  • are compression and extension adjustable independently ?
  • would it be possible to buy the front struts only ?
I'm going to start a 222E (5 bolts, it's a 2.8 200) rebuild, it will last few monthes, but I'm ready to buy the kit in advance if you need some money to earn.

That said on a 2.24V the rear swaybar isn't really needed after coilovers, as the rear ends are fairly light we've managed to remove roll with the springs.

Well I wouldn't be so sure. I have the QP4 v8 rear frame on my 430. With QP4 rear dumpers, springs and the sway bar. And the stock 430 arms. QP4 springs are stiffer: QP4 v8 is 300kg heavier. What really changes the driving is the sway bar. I understand you can improve the roll with a stiffer suspension. The problem is that a stiff rear is not good on wet or bump roads, and it's exhausting on long distances. Many performant cars have quite soft springs/shocks and really thick anti-roll bars, and this is what makes them safe and still performant.

Thanks
Alexis
 
Last edited:

alpa

Member
Messages
169
I learned directly from Biturbo testers from the De Tomaso era, that it was something that they always asked for, but that De Tomaso refused, for reasons that are very difficult to fathom.

May be the answer is that at that time the direct competitors didn't have anti-roll bars on the rear either. BMW had an almost identical rear frame and suspension and no bar.
 
Messages
198
Wow !
Finally there are REAL improvements for biturbo !
It's especially interesting for the front. rear is much easier to tune with the range of existing biT-GT-Cup-QP4 dumpers and springs.

I've got questions, forgive me if being too enthusiastic I did not pay attention to all said details:
  • is this compatible with both front and read stock springs ?
  • what are your springs ? (I have a pile of various springs).
  • are shocks some sort of inserts or is your strut a shock ?
  • are shock walls single or double layer (see the question above) ?
  • are the shocks gas ?
  • can the shock oil be replaced (serviced) ?
  • are compression and extension adjustable independently ?
  • would it be possible to buy the front struts only ?
I'm going to start a 222E (5 bolts, it's a 2.8 200) rebuild, it will last few monthes, but I'm ready to buy the kit in advance if you need some money to earn.



Well I wouldn't be so sure. I have the QP4 v8 rear frame on my 430. With QP4 rear dumpers, springs and the sway bar. And the stock 430 arms. QP4 springs are stiffer: QP4 v8 is 300kg heavier. What really changes the driving is the sway bar. I understand you can improve the roll with a stiffer suspension. The problem is that a stiff rear is not good on wet or bump roads, and it's exhausting on long distances. Many performant cars have quite soft springs/shocks and really thick anti-roll bars, and this is what makes them safe and still performant.

Thanks
Alexis
OK let me give a brief reply.
  • is this compatible with both front and read stock springs ?
    • these fully replace the complete shock and spring setup
  • what are your springs ? (I have a pile of various springs).
    • we use standard race springs we've at the moment setup springs to be somewhat firm for a V6 coupe (but still imho comfortable)
    • and for QP4 and 430 quite a bit softer as they're heavier and more a tourer
  • are shocks some sort of inserts or is your strut a shock ?
    • These are cartridges that go into billet sleeves that slot like stock shock in the knuckle
  • are shock walls single or double layer (see the question above) ?
    • monotube
  • are the shocks gas ?
    • nitrogen could be done in the setup but we decided to keep it simple as no biturbo besides a ghilbi cup car would come close to needing that, (it's just plain overkill, you'd get the notorious sub-frame flex issues etc and top mount sway before ever getting to needing this)
  • can the shock oil be replaced (serviced) ?
    • yes the are serviceable
  • are compression and extension adjustable independently ?
    • Single way adjustable damping, again we could go for more advanced but that would be beyond the use of 90% of Maserati owners)
    • Pre-load is adjustable separately from ride-height
  • would it be possible to buy the front struts only ?
    • No it's a designed as a complete kit, you'd run into serious (dangerous) handling issues by just doing half
As for the swaybar question
  • We can add thicker front sway bars to a 222,224,430 using the coilover kit, the front shocks for Ghibli/QP4 have drop links for there later style anti-roll bar
    • Maserati went in 3 stages regarding sway bars
      1. E21 style suspension no rear bar stamped rear trailing arm
      2. Shamal (1989) has tubular arms and rear swaybars yet still using the ranger diff (applicable to early Ghibli) shamal still has the old-school donuts mounted sway-bar of the early BiTurbo
      3. QP4 (1994) and later Ghibli has "Ferrari" diff and full tubular rear arms and rear sway-bars, drop-link sway bars front like a modern car
In testing FYI we found that on a 2.24V the need for a swaybar is pretty much eliminated with this kit (it's far better in rear sway control that we expected)
 

Motorsport3

Member
Messages
868
@A.S. Motorsport
Last summer I purchased a 1998 QP4 with relative little miles. The electronic suspension system works with noticeable compliance and stiffness depend what you choose. But noticed that when we have a full car (4 adults + luggages) the rear wheel on sudden potholes rubs the wheel arches. That gets nearly manageable choosing the harder setting but wanted to ask whether it is a sign that absorbers or springs had OR as Clarkson famously said the suspension is simply "diabolical"?
 
Messages
198
@A.S. Motorsport
Last summer I purchased a 1998 QP4 with relative little miles. The electronic suspension system works with noticeable compliance and stiffness depend what you choose. But noticed that when we have a full car (4 adults + luggages) the rear wheel on sudden potholes rubs the wheel arches. That gets nearly manageable choosing the harder setting but wanted to ask whether it is a sign that absorbers or springs had OR as Clarkson famously said the suspension is simply "diabolical"?
No QP4 just is to be fair (and I'm a real Maserati fan) terrible, you can get it manageable in turns if you convert over to the Thicker KS swaybar kit for a GT, but the damping is just rubbish.
It's also why on QP you always break the front lower under-body especially on Evoluzione with the scoop.

Hence we tried to eliminate the huge suspension dive issues that plague all BiTurbo's also this heavily improves the braking and the snappy back axle. (as they load up the springs and weight transfer badly causing the tricky handling)
 

Motorsport3

Member
Messages
868
No QP4 just is to be fair (and I'm a real Maserati fan) terrible, you can get it manageable in turns if you convert over to the Thicker KS swaybar kit for a GT, but the damping is just rubbish.
It's also why on QP you always break the front lower under-body especially on Evoluzione with the scoop.

Hence we tried to eliminate the huge suspension dive issues that plague all BiTurbo's also this heavily improves the braking and the snappy back axle. (as they load up the springs and weight transfer badly causing the tricky handling)

Thanks for the quick reply. As you say the car definitely dives on moderate braking and suspension is a soft, tilting on the corners. But the turn is neutral (doesn't oversteer /understeer). It's also a 2.0lt biturbo and one of the last pre-evos if that makes any difference (maybe a little on weight?)

So from your comment I understand that the suspension behaviour is what it is. Would you have more details around that sway bar you mentioned?
Would you recommend stiffer springs?