Review of RF085

I have tried to add this to the thread "A Roaring Forties with all the options" but it doesn't seem to work...

I guess it's time I finally wrote a review of my car - RF085.

In many ways the car has exceeded my expectations but this has been at the expense of some of my original goals.

I had envisioned using the car in various local motor-sport events and it has become apparent that that will not be likely. It would take effort that I am no longer prepared to put in to it.

While the car was being built, Robert Logan and I agreed that I would do development aimed at making the car a better track car. It had much built into it that would support this end. The car would however still need work when I got it and Robert agreed to provide factory assistance in that area.
To cut a long story short, that agreement foundered with the original RF. In fact it was looking shaky even before I knew what was happening to his business. I think Robert was unwilling to believe that the car was not straight away a winner, and to some extent believed that I may be the cause. He speaks well and massages egos but he is readable through that.

As an aside I never judged Robert to be a bad man, I trusted him and in the majority he did not let me down. He had a passion for the car and his business that seemed to run quite deep. I realise that some will be angered by these words and I understand that. It is my opinion that what happened to RF was despite Robert's best efforts. It seems those best efforts were nowhere near good enough and somewhat misguided, many victims can attest to that. What seems to have happened since then has changed my opinion of Robert somewhat but I still don't consider I have much of an understanding as I am nowhere near the "action". I remind that my own experience was in the main positive.
I wish for the best for those of you unfortunate enough to have been caught up in the original RF's demise and also wish RF-reborn good luck.
Enough on that.

When the car arrived it was obviously well down on the power it was supposed to have. I had asked for an engine with certain goals and got something entirely different. The tune was terrible and has only recently been finalised. I still find it hard to believe how far out it was. A rush job maybe?
After initial retuning I discovered a lovely tractable high performance street engine, still far short of my original specification, but an engine I have since found difficult to consider changing.
The main culprits as far as power is concerned, are I believe the cam, inlet manifold and throttle bodies. Perhaps not difficult to resolve, but I found myself in the difficult position of having to choose whether or not to give up one of the nicest V8s I have ever driven for something more cantankerous. More on this later.

When I received the car I drove it around for a couple of days trying to get used to it. Apart from extremely heavy steering the car didn't feel too bad so I decided to take it on faith and try it at the track. This was to be just a fun day and not a real setup and test day. My rush to try it out turned out to be a mistake.
After a few laps it became obvious that there were problems with the handling.
At this point I will point out that I have some experience with racing cars and track work and have done many many laps of my local track. I hold, in one of my cars, the course record for a local hillclimb. That car has close to 600bhp, although at the hillclimb it had closer to 400bhp using a milder engine. I believe I am qualified to drive the GT and make some comments about its performance. The car has also been driven by the man most likely to win the local rally championship this year and he agrees with my opinions.
The main problem with the GT was in the rear end and turned out to be fairly simple to resolve. It had roll oversteer like an old van. Video of a lap which resulted in a spin shows that most of the outside rear tyre was not actually in contact with the road through one corner. The wear on the tyres was very revealing also. After a day at the track, almost no tread was left on the outside while nipples/dags remained from the middle to the virtually untouched inside. This was from camber change, not from static camber being positive (which it wasn't).
Some new rear arms and some careful toying with the geometry fixed that problem. I hasten to add that this problem was in part due to the tyre which the manufacturer has since advised requires quite a lot more static camber than originally specified.
Next, with the help of Koni, some new front and rear springs were installed and the shocks adjusted. The result of this simple work was a MUCH improved car.
The car is now quite good in this area although whether or not it's good enough is yet to be established... and may now never be.
There were some other contributing factors to difficulties on the first day, a bent sway bar among them.

One of the biggest problems I have encountered is the steering. We have made some progress in fixing it but I am still far from happy, in fact it keeps me from driving the car. It was very notchy which has pretty much been fixed now, very imprecise and vague which we have not managed to fix yet, very slow (far too many turns lock to lock), and heavy enough to aggravate an old shoulder injury (curse motorbikes ) to the point that it feels close to dislocating.
Some relief was had by reducing castor by 3 degrees. I was told by an RF contracted engineer that so much castor was used to mask bump steer...
The steering geometry (including the design of the uprights) is to blame for most of this I feel and is the thing highest on my priority list.

The above may sound a bit negative but I stress that overall the car is built beautifully and most systems, such as cooling, work extremely well. There was obviously a lot of thought and work put into my car by RF.
Manufacture faults have been fairly limited and those that I brought to RF's attention were fixed by them.

As a track car it still needs quite a lot of development and, without the agreement I had, does not seem so attractive. I have other cars and one, mentioned above, is now performing extremely well in competition.

So - it seems that the GT has been retired from competition before it began.
By competition I mean things like club events, tarmac events etc, not serious circuit racing such as Ross is involved in. I was intending to do as much as I could with this car and then possibly buy another lighter version to be serious with once lessons had been learned. This was always intended as a multi-purpose car, it's just that now those purposes have been reduced in number.

Now it is time for me to thank the engine builder. You know who you are, I am very grateful to you for the engine you built me. It is without doubt the best V8 I have ever used on the road, ever! I hope my above writing on the subject did not upset you. I realise that the inlet was not in your hands and also that the cam, lifters etc are easy to change if I want to make it more "raceable". I have faith in it's strength and potential.
I am aware that engine dyno' numbers after being built were as specified and that the "problems" are mostly more local in origin.

I also thank all those that were RF that strived to build such a great car. It has its weaknesses and its purpose has changed because of them, but except for the steering, you have built me a fantastic car!

I apologise that I can't do much in the way of an "on the road" review because I haven't driven it much due to the incompatability of the steering and my shoulder.

Finally, I once again wish the best to those that have been caught in the demise of the old RF. I have been reticent to write the above because of that, but caution to the wind I guess...
I hope no offence has been caused, none was intended. I felt that I should write of my experience without colouring it too much with what has happened to others.
Once again also, good luck to RF-reborn!

Tim.
 
I neglected to mention the gearbox (6 speed Audi) - So far so good strength wise. Ratios do not suit my local tracks at all.
Diff' (by Pfitzer) works very well.

We replaced the very dodgey handbrake calipers with Lamborghini Gallardo versions and they are a huge improvement!

Otherwise, brakes are good.

Ron, please merge this with the old thread if you can.

Tim.
 

HILLY

Supporter
Tim,
Thanks for the heads up on what to expect from the RF.
I was lucky enough to see your car at the RF factory on one of my visits and visually it was awesome but obviously from your comments there are many areas to be sorted.
The sole purpose of my 40 is for street use only but it would still be nice to sort out the problems that will effect the enjoyment of regular outings. I am sorry to here that you are not even getting the satisfaction of regular street use.
Thanks for the info so far, it is always useful for the less experienced of those amongst us.

 

Ross Nicol

GT40s Supporter
Tim
Seems like you have identified some of the same problems with the RF as I have. I was similarly astounded that Robert Logan refused to support me and your explanation sounds familiar.
It became clear after speaking with former RF employees that the factory only carried out static suspension alignment. ok for the road maybe but rear steer characteristics made for interesting handling on the track. I remember those ill handling early days. I found this steering characteristic to be caused by toe out during suspension compression. By this time I had rose joints and spherical bearings fitted for full suspension adjustment. 7 degrees of castor on the rear uprights stops the trailing arms from scribing arcs that cause the problem and the toe on my car now doesn't change through full suspension travel. Setting the castor with the standard RF inboard lower control arm may not be possible due to the long bush mounting.I never found the car to oversteer due to roll in fact it has had understeer for 3 years on the track.For the meeting at Sandown just completed I had just fitted the front adjustable roll bar but the rear one wasn't finished. I uprated the springs by 100lb front and rear and the handling was transformed. The body roll was gone and it turns in like a race car should. The tyre temps started making sense too indicating the camber was under control.
I found the steering to be heavy too and took the front castor back from 5.75 degrees to 4.5 degrees. I haven't found the rack to be notchy but I did suspect the ratio to be slow until I compared it to an Escort quick rack and it was on par for measured lateral travel for 1/4 turn of steering. Sorry to hear your shoulder injury causing problems. Maybe you could consider fitting an electric power steering unit. I can't go along with a particular tyre needing more negative camber than another. It's the cars suspension and other factors that determine the best amount of negative camber, after all the intention is to keep the full width of the tread planted firmly on the track, in corners, especially the heavily loaded outside 2.
Actually I think there is a pic of your car in the Lotus club mag after the easter trip to Tassie.I was down there on the tour but had to return home early for the first race meeting. Sorry I didn't get to meet you. Next time in Tassie maybe. I really enjoy the place by the way.
Ross
 
Without the shoulder injury I could probably get used to the steering to some extent. I used to drive cars that were quite heavy in that area. I guess now I may suffer from a case of Powersteeringitus. :)
The lack of feel is a worry and the ratio reminds me of an old Falcon - sloooooow.

I think the tyres are a big factor in many of my car's problems. The car was probably designed to run on normal road tyres and may well be fine on those, I don't know, I haven't driven another RF. We knew there would be problems, that's why we had the development agreement.

This car has been on the slow burner for a while and I've been doing other things. My priorities have changed in that time. I will get the steering sorted in the end, I hope, but the car will almost certainly not see any real competition. As a road car it will (hopefully) be spectacular! :)
To be honest I still haven't gotten past the sheer joy of looking at it!

Tim.
 
Hi Ross,

I understand your comment re camber but the tyre/camber issue was brought up by the tyre manufacturer. It has to do with the way the tyre deflects. Front castor on my car as delivered was over 6.5 degrees.
I should really have done much more setting up than I did before I went to the track but I'd wanted a GT40 since I was a kid so it was hard to restrain myself. :)

Thank's very much for your input, I have been reading your posts with interest.

I wouldn't mind seeing that Lotus mag' picture if someone can send me a copy.
Sorry to have missed you. It was great to meet so many enthusiastic petrol-heads, one or two from around here as well. :)
Unfortunately my car played up when I took it along with the Lotus club to the track. I regret that I didn't take Tim for a ride.
There were some very interesting cars among them.

Tim.
 
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Tim,

I too have had an issue with the “notchiness” of the steering. I discussed it with old-RF on a few occasions and even had them inspect the car twice. In both cases they agreed that it should feel more precise but couldn’t really nail down the cause. The conclusion I made though was that the problem exists in some cars but not others, and so was unlikely to be a design issue.

Armed with that conclusion I decided to try and diagnose the problem myself. Long story short, I found that there were tiny amounts of play between the front rose-joints and their respective bolts, and also a tiny amount of play between the rose-joint housings and their respective spherical bearings. Once this play was eliminated (upgraded all front rose joints and dimpled the bolts) there was a noticeable improvement in the feel. Conclusion: steering is extremely sensitive to irregular movement in the front suspension.

This incidentally fits in with Ross’s impression of the steering feel since (as I understand) he too has upgraded his rose joints. Also, I suspect that the feel could be further improved if the lower Nolathane bushes were to also be replaced by rose-joints (as in the case with Ross’s car) but I’m satisfied with the current feel and would consider it too big a cost for what is now primarily a road car.

PS Tim. I’d be very interested to know more about the tune of your engine, or alternatively put me in touch with your engine builder.
 
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Maybe between the 3 of you agreeing, you could post a basic setup with stock suspension parts for the other owners to put on the car rather than starting with the RF specs. I would rather have it aligned the first time with something that would work better. Also Simon Hameka put a different steering rack in his car , It would be great to get some input from him, about steering feel, effort and such. Thanks, Dan
 

Ross Nicol

GT40s Supporter
Hi Dan
What your suggesting sounds fine but I think although 3 of us agree there are some flaws in the basic RF suspension, each of us has corrected/modified
things depending on use of the car and what we percieve to be a problem. For instance Tim and I have taken castor off the front to lighten the steering but Chris L hasn't mentioned it, so I presume he's happy with the steering weight. My car is a track car only so suspension settings are critical and my springs are way too stiff for road use.I think we could put our heads together though and help guys like yourself start with corrected settings.I personally would like to pass on what I think is a safety issue. As I seem to keep banging on about rear steering, I do it because a car that steers at the rear is fundamentally dangerous on the road or track. It is true that a road car may never be driven hard enough for this steering to occur but all cars with the classic 60's independent rear suspension should be checked and corrected before any static settings are made. And the reason this order is important is the dynamic settings will upset any static ones and nullify good handling.We still won't be able to account for personal tastes though.
As they say " some like it hard ". Of course I try things based on experience, books, experts in a continuous development path for my race car so a lot of my development may or may not be helpful to others. See what the others think Dan.
Ross
 

Ron Earp

Admin
Hi Tim,

It is good of you to put a post up like this as an objective and knowlegable view is useful. Ditto the thoughts from others on the thread. Not enough of these floating around on respective cars and related topics.

Cars need development and I knew the RF I didn't get would need some work to perform well, but it is part of the fun. Once the car is built, or bought, the development begins. Some issues can be taken care of, but some like brought up in this thread, take some re-design and hard work.

As you fellows work through development and share what you've already done I'm sure it'll help RF owners all over.

Ron
 

Keith

Moderator
ross nicol said:
Hi Dan
As I seem to keep banging on about rear steering, I do it because a car that steers at the rear is fundamentally dangerous on the road or track.

The 1960's Alan Mann Lotus Cortina's were infamous for rear wheel steering resulting in some strange cornering attitudes (they may have been the first "tripods") but generally much quicker than the opposition. In fact it was one of the reasons they were so damned quick! Didn't faze the likes of Jim Clark, Graham Hill or Sir John Whitmore though, but there again, not much did.

Involuntary and unpredictable rear wheel steering on the road is, as you say Ross, dangerous.
 

Pete McCluskey.

Lifetime Supporter
Excuse my ignorance guys , but can someone define what "rear wheel" steering is? I know what bump steer, oversteer, understeer, pushing and loose means, but have never heard the term rear wheel steer.
 

Ross Nicol

GT40s Supporter
Good question to ask Pete. Rear wheel steering can occur in cars with independent rear suspension. What happens is a rear wheel changes from zero or toe in to toe out during suspension travel.Now imagine what happens when you turn into a corner, the outside rear wheel loads up and compresses the spring, that particular wheel if it changes to toe out at this point will steer the rear end and may cause the car to oversteer. Oversteer being an unstable condition as I'm sure you would know. I think I'll do a suspension what to do and goal in the chassis Forum.
Ross
 
It can also happen due to flex in joints.
Poorly located live axles can steer.
There is also "designed in" rear steering but that is another subject.
As Ross says - a change in rear wheel toe in/out.

Tim.
 

Russ Noble

GT40s Supporter
Lifetime Supporter
The most obvious cause of rear wheel steer (bump steer at the back, Pete) is placement of the lower radius rod forward pickup point too high on the chassis. You can't run a high forward pickup point with a reverse lower "A" arm. This can be partially compensated by running increased caster which has the effect of raising the height of the rear of the radius rod but this negates the effect of the high forward pickup.If you want to run a high forward pickup to provide some anti-squat or whatever then it is advisable to go to twin parallel links in place of the reverse "A" arm. That way the toein won't change as the upright moves backwards and forwards due to the angle of the radius rod.

Cheers,

Russ
 

Ron Earp

Admin
Russ Noble said:
The most obvious cause of rear wheel steer (bump steer at the back, Pete) is placement of the lower radius rod forward pickup point too high on the chassis. You can't run a high forward pickup point with a reverse lower "A" arm.
Cheers,

Russ

How high is high? Or, how much above the roll center is deemed "high"?
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Ron,

Basically it's a function of the angle of the radius rod in side elevation. If there is excessive angle at static ride height from the horizontal then as the wheel goes into bump the radius rod will push it back. With a reverse "A" arm the upright and wheel, in plan view, pivot around the inboard pickup point causing toe out. The reverse happens in droop. With twin bottom links that won't happen. Ideally from a bump steer point of view the radius rod needs to be approximately horizontal to minimise this effect. However there are other considerations, which others will be more knowledgeable about than me, and as with everything the final solution winds up as a "best compromise". That's one of the reasons I chose to do a scratchbuilt, I can decide myself on the compromises that I am most happy with!

All the best
 
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rear links

Russ

I under stand everything you said & it all makes sense but im trying to figure how the links would be different than an A arm.
If the front links are mounted in the same spot with twin links would it not still toe out or am I missing something.
It may be a simple sollution.(worth checking at least)

Jim
 
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