I would imagine thats why the stuck the big rubber bushes into the equation to allow for movement, which actually made things worse
I would imagine thats why the stuck the big rubber bushes into the equation to allow for movement, which actually made things worse
S4sevenl,
Sorry but I do not have a chassis number for the S4 recorded. The reg. was GR 7169 and I have it down as a 1973. It was silver in colour late 1980's.
OK Paul,
Running the control arms forwards would surely have cost less than running them backwards, because this would have obviated any necessity to stiffen the rear of the chassis, as it would then have not been loaded by the suspension. Money was wasted rather than saved. No Kiwi special builder would make something so utterly stupid.
From what I have read, Chapman did not design the S4, which was the brainchild of his underlings and he was only called upon to take it for a quick test drive before giving it the OK. But why did he do so? At the time there were financial problems and Chapman must have had his mind on other things, including his creditors. The S4 was supposed to cover a more extensive market sector and was no doubt originated by those hopeful of saving their jobs.
This was done on some engines back then to give better toque. Thinking back then was Longer manifold = torque. Did it with a 2Ltr Ford for speedway skidder way back and it did definately improve low down grunt. Run heat shield under carbs and big elongated u - shaped inlet pipes back over rocker cover, and boy racer bulge in bonnet to make room.Originally Posted by jim short
I'm not an engineer (I just play one on TV) but I think they were just trying to be clever, using an (in-effect) straight-line generator at each end of the axle. Either they realised they weren't as clever as they thought and had to bodge it rather then to admit to wasting a fair bit of time and money, or they weren't given the time/budget to develop it. Chapman, I think had moved on and just wanted the cashflow a new Seven would bring. He gave it to the underlings while he was off on other projects and just as many times he had benefited from the great things they did, this time they fell over.
To be fair though, I think if you had tested a new S4 within the parameters of it's intended use you would have experienced no adverse handling whatsoever. Remember they didn't really have any competition aspirations for it. Having said that, my old S4 could be bunged through the twisty stuff as quickly as my current Leitch by a try-hard such as myself, I imagine it would only be the real drivers who would find the shortcomings and they weren't the target market anyway. You are right though it is an arse of a design...
As a matter of serious interest, the idiocy of the S4 thing has plagued my mind for a long time. Please elaborate on “straight line generator at each end of the axle.” I guess you are indicating that it was intended that the axle should be accurately located perpendicular with the chassis centre line, i.e. and essential requirement.
I also am no qualified engineer but it is easy to understand that what amounts to a Watt’s linkage at each end of a solid axle, absolutely prevents any roll and which as a result can ONLY occur when and if the support points are stressed beyond their limits, i.e. by accident, surely not by design. The only logic which can be applied is that the designer did not realise/understand the effect imposed by the as used, stupid for and aft locating system.
I drove the thing under normal road conditions after purchasing it and took due note accordingly. The success of clubman type cars is due to the fact that they were/are marketed for real drivers, who appreciate tactile handling to the extent that they are willing to discount luxury in order to enjoy this aspect of motoring. The S4 was a flop cunningly off loaded. Having noted the wonderfully engineered steering and suspension set ups on Steel Bros. heavy multi wheeled truck trailers, it surprises me that they did not fix things. Mesmerised by the Lotus image I guess.
Yes, an arse of a design for sure! LOL. But the question lingers, there can be no excuses, just how did it see the light of day within such an illustrious environment??? The mind boggles!!
Yes Rod it sure did talk and ram the stuff in great guns and low down, grunt out loud. Raises the talking point of, pity the poor old Chrysler Corp. Ouch!
Trevor
Just as a side note, you old car is alive and well, having had a rebuild in Christchurch. The interesting thing about this car was in the early seventies it was on wire wheels
S4seven or whoever,
Thanks for the info. Bolt on wire wheels? Are you certain?
The current owner should find that he has somewhere to put his left foot, he can operate the brake and clutch properly and heal and toe. The steering wheel is forwards for a straight arm position. It is not inclined to lift its inside rear wheel when cornering on the limit and it keeps its back feet on the ground. The steering rack is rigid and the mount is not cracked. Numerous persons have welded and brazed up the chassis frame at various points. The electrics should be much better than when new in various ways and the lights are lightweight and non standard. Much more, but it was a long time ago.
It was very sad when I got hold of it and I later learned that even then it had had a hard life, which included some racing. I am very surprised that it is still alive. Please advise the owner that I would very much like to make contact.
Trevor.
Trevor
They were knock on's, the picture I have is to big to load, have you an email I can send it too
Kia ora Paul,
Mr Watt was a brilliant steam engine man and his idea was originally applied accordingly. He would be annoyed with Mr Chapman and rightly so.
Correctly used in the automotive world, a single Watt’s link can absolutely restrict the sideways movement of a rear suspension system and does so more accurately than a Panhard rod, which involves a radius of movement. Even so, the link does present problems in fixing the most desirable roll centre. There is no way the S4 set up, could have been satisfactorily used for front rear location in a more sophisticated system. More particularly in a de-dion rear end, where again a rigid connecting tube is involved thus coupling the links.
Sadly Mr, Chapman has no excuses in spite of the ongoing hype which follows him and you better believe it. LOL.
Whatever, go here, click on “The Lycoming Special” and you will see how a real engineer goes about these things.
P.S. Trying again for a hot result!HTML Code:http://ralphwatson.scienceontheweb.net
<http://ralphwatson.scienceontheweb.net/>
Cheers, Trevor.
Last edited by Trevor Sheffield; 01-07-2012 at 09:50 AM.
Thanks. trevshef@xtra.co.nz
Do you know what happened to the original knock on wheels and hubs?
Hi,
I am new to this thread, congrats on buying the black car. A couple of things , when Aldas raced this car he engine was a trick unit from Randall, this is how Charlie aquired it. When Charlie sold the Brabham to the Wootons the engine out of the 7 was swapped. The engine out of the Brabham was rebuilt by Ian Chase if I recall and stuck back in the 7,this car always had wide 13 inch hotwires on it abd my friend Graeme Pearce sold Charlie the Simmons 15 inch wheels. I see a couple of points about the rear suspension on the 7,there are a couple of notes
A Watts link moves in a very shallow S pattern, that is why it is preferred over a panhards arc. On the 7 with a watts on each end of the diff moving in S shapes or only one side you would bind the diff if no movement in the bushes. If it had rod ends on everything you would either break the chassis mounts or twist the diff(i am sure the chassis would break).I am sure this was meant to be a zero steer rear end. The problem with a 4 link rear with very short links is roll steer and and also roll bind. Even a 4 link with long link will get roll bind at some point in its travel. This is compensated by either flexible bushes in one end of link or as a V8 suppercar does you use a plunger type rod with a small amount of movement and controll this with belvell washers. Whoops that was a bit long winded!! any way what I am trying to say everything is a comprimise be it a 4 link ,3 link or even the S4 7 rear. I race a BDA escort and have had alot of experience with a 4 link and there is comprimise. I have also had quite alot of experience with S4 7's. My father is Richard McCarthy and had campaigned a S4 7 for many years. This car became quite developed and is still probably the quickest S4. The rear chassis is heavily braced around rear chassis mounts, uses rod ends on both end of forward links and only on one end of rear link. It seams to work well, hooks up great of the start, doesnt seem to have strange roll oversteer. This car was written off last year when it was T boned by a cobra at Hampton, it is almost back together. When you see a S4 bare chassis it is quite frightening. I particularly like the steering column bolted to the GRP scuttle! When we first mucked around with my dad's car years ago, I remember unbolting the radiator and leavint the side plates on the chassis, it wouldn't come out. We jacked up the front on the car lifting the wheels off, radiator came loose. Result was bracing behind the radiator.Any way good luck Paul.
Paul (4dnut) I have sent you a PM
Hi just talking to rex nalder my prev.thread may be incorect he bought the black 7 off a soldier that had sat for some time in midle of the country,,,he maintains it was a special lotus ex eng,,after completly blowing original mtr at wigram 82 83?jamie fited a bda and modified it he cant remember who bought it,, of him and has no interest but i think it is the same car!!!
Hi Paul just rang jammie am now more confusedhe like me was shure it was a steel bro..never had a bda carbs never on exhaust!!sidethis was done on ford 10mtr in the50s manly speedboats,just the names mentioned seem to fit the nalder car???
Hi Paul, I have sent you a PM, I have my dad's car at work if you want to look at the chassis mod we did for the dry sump pan
Paul
I have the Bainbridge Lotus 7 (907 engine) they built after ‘acquiring’ from Steeles. It has an S3 body but on what would seem to be S4 wider chassis and also the rear suspension as described in this thread.The only way that the rear could roll was for the chassis to flex, or for the suspension points to yield. I scrapped the forward facing arms and fitted new trailing links, together with a Panhard rod. This with other corrections, turned it into a motor car. Just what was Chapman thinking about?
I do not think I have the chassis number recorded anywhere, but will be pleased to check for you. Last seen in was down in the Waikato somewhere.
On a winter rebuild of front suspension, although wasn’t done for racing, a mechanic friend (& racer/builder) suggested we look at rear set up while on stands….& he spent a fair bit of time shaking head as to design & associated risks of flex & damage....let alone handling deficiencies. His ideal option was rebuild, as described by Trevor, but for budget reasons opted to rose-joint key points to allow flex – and in particular to protect the chassis which seemed to be the biggest risk of damage should untoward occur.
Another option/thought to the mix I guess…..
S4seven. where do the numbers "3060" and "3995" fit in?
what info can you share on the two chassis numbers. 3060 is in the range for steel bro build cars, but 3995 doesn't in to the NZ or UK list of chassis numbers
The value of having a good strong roll bar on a Seven..bit off topic, but some good footage here...
S4seven.
I am looking forward to receiving the photo you promised, as well as advice regarding the knock on wheels. To assist further, I repeat my e-mail address:-
trevshef@xtra.co.nz
Trevor.
Posting Permissions
Reply With Quote
