rotoflex / non rotoflex - what's better?

[Sam C]

Sorry - this is probably a stupid question but it's been in the back of my mind:

My mk3 Gt6 was sold with a description 'non-rotoflex rear suspension'.

At the time I wasn't that fussed - I'd heard GT6s had poor handling and expected to have to put up with it. However, I half hoped it was the rotoflex version that was rubbish and I was getting the 'better' one.

However, was I wrong? What sort of suspension would it be if it's not rotoflex and is this a good or a bad thing?

Cheers chaps

[GT6Craig]

Well i hear that rotoflex suspension needs attention at least once a year....mines non rotoflex and its so simple to work with thats an immediate winner in my opinion..as for handling, i went from a Cortina Mk3 to 1985 VW Polo to GT6, so it handles like a Ferrari to me!

[rotoflex]

There were 3 original GT6 suspensions

Swing axle:  on the GT6 Mk1
Rotoflex:  Mk2, early Mk3
Swing spring:  late Mk 3

In order of motoring delightfulness, they are

1.  Rotoflex
2.  Swing spring
3.  Swing axle

with rotoflex of course being the most delightful.  This is not to say there is anything distressing or deadly or fundamentally causing ruin of a day's drive about the swing axle, the swing axle was fine for most driving short of the track.  The swing spring was really an economy move to cut down on manufacturing costs.

The rotoflex suspension doesn't require attention once a year, the donuts must be replaced more like every 3 years in regular driving.

It's interesting that Sam C & Craig both have the non-rotoflex suspensions in their GT6s, but they are different suspensions!  

If Craig's interested, he can easily change from his Mk1's original swing axle to the later-type swing-spring for a little more confidence in the turns.  It's pretty much a matter of swapping out the rear spring for a spring from one of the swing-spring Spitfires.  The BL/JRT US Competition Dept. issued a memo on how to do it:
http://www.geocities.com/rotoflex/gt6-mod.htm#_Swingspring_conversion

[Tim Bancroft]

I have driven cars with the 'Swing Spring' arrangement, however I must say that always felt the rear suspension to be a little loose in feel, bad bumps and the like causing deflection.

I like the rotoflex type suspension and largely found it to be relatively maintenance free, in fact the doughnuts helping to preserve the life of the in-board uj. Re-building Roto suspension is a pain as one is always attempting to manipulate the rubber coupling to attempt toline up the suspension joints. The rear end on these cars does feel better located and a bit more predictable. However it is essential that the geometry is checked when ever the suspension is worked on.

The GT6 is very much a 'slow in, fast out' type of car. If driven without finesse, understeer (The engine's weight causing the car to plough on at corners) can quickly turn to oversteer, the cause of many a death of a GT6! The chassis is not that communicative so it can be difficult to really feel what is happening! Still once mastered they are delightful to drive, the best roads being sweeping well surfaced A roads, more intricately cornered and poorly surfaced B roads show up the limits of poor suspension travel and therefore limit speed.

[MarkB]

I my experience the swing spring set -up feels a lot more skittish as soon as you hit a bit of uneven road, it has a tendency to hop and skip. Can be made to handle better by lowering etc but then you have problems with speed humps etc. Rotoflex feels a lot tighter, smoother and sure footed to me.

[Nick Jones]

IMO the rotoflex does give the best handling and road holding.  This is due to the reduced variation of camber keeping more of the tyre tread on the road more of the time and reduced amount of track change minimising the skittish feel common with the swing axle/swing spring arrangement on rough surfaces.

That is not to say that a well sorted swing spring car can't out-handle a standard or poorly setup roto rear, but they do (as already mentioned) usually need to be pretty low to acheive this.

The roto rear is more complex and can be difficult if problems arise.  However, if properly overhauled with decent components (no repro rotoflex couplings!!) they are very reliable and far less prone to UJ failure.  They are also less likely to shed wheels due to shaft breakage......  Fit CV joint shafts for 'fit and forget' reliability.

Having said all that the Mk3 GT6 does have the best of the rest with the long shaft swing spring arrangement shared with the Spit 1500.  Pity about the self (non) adjusting brakes though  :P

Cheers

Nick

[rotoflex]

Another variation is addition of the Camber Compensator on the early swing axle cars
http://members.cox.net/spitlist/CamberCompensator.html

The Camber Compensator modification was a performance improvement modification to the swing axle cars which preceded the introduction of the swing spring (and rotoflex) suspensions.  I do not know how its performance is ordered in the list, but I sort of feel like the swing spring probably might be better since Triumph developed and used the swing spring in later cars instead of incorporating the camber compensator.

[mikeyb]

rotoflex wrote:

I do not know how its performance is ordered in the list

I think the swing spring would be better, reckon you would lose a fair bit of ground clearance with the compensator

[Madaza]

Guys, been thinking about the GT6, but have been put off by its reputation for 'interesting' handling. I'm particularly interested in the MK2 - is there a workaround? How about aftermarket suspensions? Coilovers? How difficult/expensive?

Many thanks.

[Clive]

GT6 can all handle well, but as above I think fitting the late swingspring to a MK1 is the answer, all others pretty OK as long as everything maintained. Rotoflex is good on MK2 and early MK3, if concerned about the rubber rotoflexes fit the CV stuff, if you think it is worth the expense.
clive

[Deleted User]

Madaza, who tells you that the MK2 GT6 has a reputation for "interesting handling".  The MK2 GT6 is a Rotoflex car, and handling wise is very benign, so whoever says that it has a reputation obviously doesnt know what they are talking about.

If you insist on updating the suspension, then try one of the PRIACE kits.  http://www.prirace.com/suspension.htm

[Madaza]

Kevin, thanks for your input - trouble is every time someone tells me it's not an issue, someone else tells me it is. And then I see pictures of cars with massive positive camber...... I'm a little lost to be honest.

If I may clarify, I have very little experience of classic cars - but quite a bit on modern performance cars (road and track). I don't expect for one moment to be able to get a GT6 to handle like a Noble (having said that it's all in the suspension, so if one is willing to put up the money, there's no reason why it shouldn't.....within reason). But, there is no reason why it has to handle like a poor 1960's vintage saloon either. I guess the question is; can it be made to handle in progressive manner for fast road/track use?

.............I apologise if I've just inadvertently insulted someone's car!

[JohnD]

Madaza,
Here's George Ralph of this parish, getting up Longleat heill climb at a respectable rate:  http://uk.youtube.com/watch?v=KUgkCRgpDpE&feature=related .  Interesting? For all the right reasons.
Or this US Autocross clip: http://uk.youtube.com/watch?v=w9b_kGna-kM in a "'68" GT6 which might be sqing axle or Rotaflex, but could be latter modded to swing spring, but seems not to spin.

You are probably up to speed on Triumph 'small chassic rear suspensions now - for GT6, Mk1, swing axle, Mk2 Rotaflex, Mk3 swing spring.    Rotaflex was a remarkable improvement, but so was the swing spring, that Triumph went over to for th GT^6 having proved it on the Spitfire, because it was lighter and cheaper.
I've raced with both rotaflex and swing spring.   The latter's only foible is to break half shafts, but this is unknown (AFAIK) for a road car.

John

[Deleted User]

The pictures that you keep seeing with massive positive camber are actually very rare.
The pictures are of fixed spring Heralds, GT6 MK1s and Spitfire 4, Spit 4 MK2 and Spit MKIII.
To get the positive camber shown in the photos takes a lot of effort, and just because some test driver managed to do it in the 60's doesnt mean that every driver is going to encounter the same problem.  Remember the Smart Car and the "Moose test" - it took Smart years to loose the reputation it acquired because a journalsit performed a rather silly manoever in the test car.

[CharlieB]

KevinR wrote:

If you insist on updating the suspension, then try one of the PRIACE kits.  http://www.prirace.com/suspension.htm

That kit looks like expensive nonsense to me. It removes the swing spring & is therefore no better than a fixed spring setup, all be it adjustable.

[Deleted User]

CharlieB wrote:

That kit looks like expensive nonsense to me. It removes the swing spring & is therefore no better than a fixed spring setup, all be it adjustable.

Yep !, but Madaza wanted to know if the suspension could be modified, and how much, as someone has convinced him that the stock setup is not very good.

[Madaza]

John, thanks (again) for your advice! The longleat car does indeed look pretty well planted. The autocross one looking stable, if a bit understeery (grammar!) with bodyroll. If you say the GT6 is a  decent (fast) drive then I happily take your word for it, and will readily accept other whispers as being folklore.

Kevin, Likewise thank you. The trouble is a live axle is dynamically deficient, one cannot get away from that. The elk test may have shown an oddity in the A class handling - but it WAS an oddity that existed. If one is to drive these cars anywhere nearing the limits then the characteristics of extreme handling cannot be ignored.

Having said that, I haven't experienced the car and welcome every view point to help me decide - so thank you both.

[ferny]

GT6, Vitesse and Heralds all understeer a bit. The 6 cylinder cars more so from the extra weight up front. I've never driven a Spitfire but they appear to turn in better from what I've seen. They look to have better balance. I can't see it being a problem in road conditions and I've certainly never experienced it on the road except in greasy conditions. They all seem to go well in motorsport. The only part which worries me is having to do an emergency change of direction when the cars weight is all over the place such as on a crest. But all cars are iffy in those situations. I don't expect standard cars to handle as stably as mine, but then they wouldn't be driven in the same manner either.

The GT6 got its reputation for dodgy suspension from the Herald. Probably down more modern types of suspension become common at the time. Don't forget that when the Herald was launch it was, erm, heralded... for how it performed. The Mk1 GT6 was said to have soft suspension which made the back squat when you put the power one and the front dip when putting on the brakes. The reputation stuck to some degree. I believe the swing-spring was a by-product of the Le-Man Spitfires.

Tuck under isn't really a problem. I've had it twice in my Herald and I've been known to drive spiritedly. In fact it makes you a better driver in many ways. That paranoid niggle in the back of your head makes you take bends more smoothly. Not that they can't be chucked around too...

Chances are that the people who are telling you about poor handling have never owned one. Perhaps they've driven one once at most. I'd say the chances are that they're book experts. The type of person who reads a book or an article and suddenly knows everything about the subject.

Go drive one and see what you think. Tyres, steering wheel sizes, bushes, etc. all make big differences on these cars so it's hard to tell you exactly what you'll experience as each is different - that's just my view. But safe to say expect positive steering feedback and it to be rather nimble (especially at speed). Oh, and decent poke.

[Clive]

The other thing to consider is the suspension as a whole package. My spit had a swing spring rear and 480lb front springs with reasonable shocks. Handled pretty well, nothing untoward worth mentioning. And I hadn't fully sorted it. Strangely the youtube of it going up prescott has been removed by whoever posted it :'( (BUT avoid oil on the road :B it bends cars)

[esxefi]

uprate front springs and anti rollbar,

slightly lower rear end swingspring,

fit low torque antirollbar to rear and lsd.

jobs a good un'

[JohnD]

Swing spring AND a rear antiroll bar?
The point of the swing spring is to reduce roll stiffness and prevent the unweighted wheel 'jacking-up' the suspension.
The ARB will increase roll stiffness, so inducing jack-up again.

But a 1" spacer under the spring lowers the car and puts the wheels into negative camber at rest.
Less likely to get into positive camber in use.

John

[Madaza]

Thanks so much for all the replies. I'm a little surprised that such a popular car with (some would say.....I know....) a slightly dubious suspension setup hasn't got a recognized fix after all these (30+) years. Perhaps the problem isn't as great as the whispers would make you believe, but after such a long  time someone must have said 'to get a really well handling Spit/GT6 this is what needs to be done'. Or no?

[neilnaz]

Madaza this works:

Get decent adjustable shocks at the front and 330-480lb springs preferably around 9" free length.
Polybush red or similar all round
Decent rear shocks for the rear
Adjust the ride height with adjustable seats and lowering block at rear (if necessary) so the car sits with 1" or less distance between tyre top and wheel arch front and back.
Adjust front and rear camber so you have at around 1 degree negative rear and around 1/2 degree negative at front
Obviously get some decent fresh rubber and wheels (5-6J) (I like Revs  :))
Get all 4 wheels laser aligned once you have got the ride height and camber sorted.

Some of this is personal taste and how you drive your car. Most people will be very happy with standard setup as a Spitfire as standard has around 70BHP and is not a fast sports car. However even as standard it handles pretty well. The issues mentioned are only at the limit and with some of the earlier Spitfires as mentioned.

If you are really worried about such extremes which are rendered highly unlikely by adjusting as I have described then go for a 1500 set-up which (IMHO) is the most stable set-up. It really isn't needed unless you are a real fast driver and drive constantly on the limit. The settings above are a guide. Some people will go lower and advise more negative camber at the rear. My stetings are a compromise of handling and ground clearance (speed bumps..  :-/).

I do not think there is one simple answer which you seen to be looking for as each of the cars is different and each driver wants anything from original period charm and a standard car to balls-out racer with 150BHP+ (i.e. engine swap) and the performance of an Imprezza.....

I have never driven a Spitfire which wasn't fun to drive. When i got mine it was in fairly standard guise and it went nicely. It sits better now, is more planted and purposeful and has more power to boot.

You need to make sure everything else is in good nick especially the brakes. I have Mintex 1155 pads and they are great (far better than green stuff yuck) using standard everything else including discs.

What you need to do to the car you get depends on what you want and what state the car is in when you get it. Half the fun is making the car what you want but it is the most expensive way of getting there.......... ??)

[Richard B]

It's not that bad on the early cars; better on the rotoflex and improved on the swingspring.

Like a lot of things these stories then degenerate into 'Urban Myth'. I think the problem was supposed to be more pronounced on the MkI Vitesse, a combination of high roll center, 100bhp to the ton (ish) and heavy understeer.

Like a lot of cars, lots of power tends to show up deficiencies in the handling and they become more noticable at the extremes. One of my daughters as a 1200 Herald with a swing-spring conversion. The other has a 13/60 Estate with the standard spring but 1500 driveshafts (not our conversion). I have a MkIII Spitfire, but with rotoflex as it has 160bhp from a PI.

Find the car that suits you, get to know the handling and then decide if it needs changing or just 'tweaking'.

[Tim Bancroft]

Sounds like you need to go for a ride in a GT6.

Where are you based?