So when is a Terrapin a 'Terrapin'?

[MiNiTiCi]

So - What constitutes a 'Terrapin'?
I have been interested in Allan Staniforth's Terrapin race cars since first reading about them in his excellent book "Race & Rally Car Source Book" way back in 1985 and subsequently getting a copy of the original " High Speed Low Cost - The story of a 140 mph Mini engined world record breaker and how to build it".
I have often wondered what constitutes a 'Terrapin' ?
From what I have seen, no two examples are the same and they have often undergone evolution during their long racing lives.
Is the essence of a 'Terrapin' Allan's chassis and suspension design or is it the cars Mini derived hubs, drivetrain and engine, or some other loose interpretation of Allan's original design?
Allan's original chassis design incorporated spaceframes with diagphram bulkheads and stressed skins which would appear to be a precursor to the full monocoque type of chassis prevalent from the 70's.
Albeit - some of the later design Terrapins used a tube frame rear bulkhead instead of the diagphram type and I believe that the wider bodied Mk5 sports version's front bulkhead was also tube framed.
Various different engines have been used in Terrapins over the years - Allan experimented with Hillman Imp lightweight alloy engines mated to Mini gearboxes and another early Terrapin used an NSU engine.
Allan's ultimate Terrapin was perhaps the Gould-Terrapin fully triangulated spaceframe two piece chassis with 1600cc BDA and Hewland gearbox - but still identifiable to the Terrapin roots.
In recent years Terrapins of all vintages have been seen with motorbike engine/gearbox units with chain driven diffs. Indeed these cars are able to be competitive with much more modern machinery - at a fraction of the cost.
So if I want to build a 'Terrapin' and want to call it a Terrapin - what elements of Allan's original designs do I need to incorporate?

[Mr Locost]

It's the same as the Locost.

The original locost had a Kent engine, escort rear axle/propshaft, Cortina Front hub assembly + brakes, nova steering column, escort steering rack.

Now alot of people are building them 4" wider with a bike engine, sierra rear IRS and propshaft, sierra front hub assembly and brakes, sierra steering column and a sierra steering rack.

As technology moves on so will the cars.

Basically, Terrapin is a theory, the same as Locost

[Jawfish]

That's a good question ;D...

As the Terrapin is the original Low-Cost I would say it's more than a car but a state of mind. Building a real race car with a low cash outlay. Let's face it, Alan's book help a lot of us realise that building an open wheel single seater was something we could accomplish, in fact some Terrapin builders latter went on to build incredible new cars of different names.

I think for a Terrapin to be called a Terrapin it must be at least derived from the original plans either suspention or frame etc... I wouldn't call a carbon monocoque single seater with inboard suspention and a cosworth V8 a Terrapin .

But the Terrapin name is Alans creation so I guess he is the one who would need to put his seal of approval in the end.

Fred

[twentyover]

Maybe like Mallock's U2- I don't know that there was a U1 or U3, but the U2 contained a number of design variations over the years.

[Terrapin]

Nice to see so much dialogue on this - I must admit I've build a MK1 terrapin - so for me it's mini engine ....etc...etc.
I must reiterate though, I started my build from a desire to own a piece of history and have some fun.
I don't delude myself for a minute that the car will be left standing by our bike engined collegues.
I have stayed pretty true to design (bulkheads etc.)
but used vented/4pot brakes.
I have anumber of spare engines and also just aquired some Eaton BMW cooper S supercharges to play with.
I am also being badgered into have some Terrapin specific meets at the Haynes motor museum track (keep pushing Nick!)

To me, the most fun is in the building and I always like to have a project on the go.

I also must admit I get a little disheartened when I see classic Terrapins having the mini motor removed for a bike motor

Keep up the good work guys

[MiNiTiCi]

Rob,
You must be congratulated for building your Mk1 Terrapin true to Allan's original design. The photos on your web pages certainly shows that you have done an excellent job.
I'm sure I have already berated you for adding those overly heavy metro, vented 4 pots.
On Allan's Terrapins he appears to have tried to use the slimmest discs
(then skimmed them down some more!).
But no doubt you are plotting to fabricate some ultra-light billet alloy calipers to compensate.
Yes those BMW Eaton superchargers certainly looked nice and cheap on e-Bay and even the complete Vmax supercharger kit for UKP1650 is still pretty reasonable.

Mmmm.. Terrapin 'track days' that sounds good.

With regard to originality of Terrapins, perhaps Allan could lay down basic specifications for the various Marks of cars built to date? Mk1, Mk1A, Mk2, Mk5, Mk7......
Then perhaps create Mark number(s) for other engined cars such as bike engined? - Just a thought
Doug.

[Ian]

MiNiTiCi...When is a terrapin not a terrapin? I have got no idea....Mine transformed into the megapin when Allan finally decided the resemblance had moved so far away from the design as laid down in his original drawings, that there was more of my thoughts than his. I think Allan is prouder of the concept rather than one sticking rigidly to his plans. Even twenty years on Allan and I have stayed true to his original premise that short swing axle lengths etc bear more importance than the layout of supporting chassis tubes. (Not to the point of losing perfect triangulation that the original Terrapin offered.) So when is a Terrapin not a Terrapin ...I.ve got no Idea..Ian..

[Terrapin]

Nice one Ian.

[Terrapin]

PS - I've asked Allan if he could write a little piece for the forum. Grateful if you could pester him too Ian. ;D

Is that Bizzy Williams I see as a new member?
An old rum punch pal of Allan's Barbados days.

[twentyover]

Regarding Staniforths choice of brake rotors- If i read correctly, he used the car primarily in Hill climbing- hardly a form of racing that severly taxes the brakes heat-wise.

I would think a track car might benefit from better brakes- I'd be looking at cars similiar weight and maybe a little greater performance. What are vintage Formula Fords running?

For my own plans, I'm looking at the hot D/SR guys to get a feel of what they're doing, and head essentially the same direction

[MiNiTiCi]

twentyover said:

Regarding Staniforths choice of brake rotors- If i read correctly, he used the car primarily in Hill climbing- hardly a form of racing that severly taxes the brakes heat-wise.

I would think a track car might benefit from better brakes- I'd be looking at cars similiar weight and maybe a little greater performance. What are vintage Formula Fords running?

For my own plans, I'm looking at the hot D/SR guys to get a feel of what they're doing, and head essentially the same direction

As you say, Hillclimbing does not overly tax the brakes heat wise - They just need to bite at the first corner
My 1976 Hawke ex.FF1600 still uses good old iron Cooper S calipers at the front with solid rotors of about 9" diameter and 0.28" thick. Rears were similar but with the smaller Cooper calipers. (FF1600 regulations stipulated iron calipers). I now have Suzuki bike 2 pot alloy calipers on the rear but these give me clearance problems on the inside of my wheels.

I have seen a few race cars which use the readily available (and cheap) kart rear rotors mounted on special bells and using light alloy calipers. The kart rotors can be solid or ventilated.

Perhaps this is topic should end up in the 'Technical' section?

[Jawfish]

I like were the topic is heading about when a Terrapin is a Terrapin, I do agree that the brake direction should be in tech, therefore I'll post a new tread in tech about brakes, since myself I have a few questions.

Rob, Yes get Allan to write something, I'm sure we all would look forward to reading it.

Fred

[JH]

I think that just about the only thin that remained standard(ish) was the suspension geometry. I knew of some cars with alloy or fabricated steel uprights. Some builders stuck faithfully to the plans, others put in their own ideas. there was a small army of drivers out there all doing their own development. David Gould (needs no introduction) & John Corbyn (of Jedi fame) were both guys who cut their teeth building & developing Terrapins before moving on. There was even a couple of monocoque cars which kept the same basic geometry. My own plans were for a mk1a, but came with Allan's red pen all over them to reflect the then (1980) current thingking.

[Terrapin]

Yes, Allan still updates the plans when builders feedback anything of note. I noticed a couple of errors when building mine and Allan has corrected the plans.
There was a small run of alloy uprights made by a register member may years back and these are documented in the news letters (120 monthly bulletins were issued in total)
I have a copy of each one and ned to sort them out when time permits)

[MiNiTiCi]

JH said:

I think that just about the only thin that remained standard(ish) was the suspension geometry. I knew of some cars with alloy or fabricated steel uprights. Some builders stuck faithfully to the plans, others put in their own ideas. there was a small army of drivers out there all doing their own development. David Gould (needs no introduction) & John Corbyn (of Jedi fame) were both guys who cut their teeth building & developing Terrapins before moving on. There was even a couple of monocoque cars which kept the same basic geometry. My own plans were for a mk1a, but came with Allan's red pen all over them to reflect the then (1980) current thingking.

Hi Jeremy,
Do you still have your Hawke DL16's?
I recall that you said that you used to have a Mk1 Terrapin, with a 1071 'S' motor, which you built when you were an apprentice.
Nice to see you on this forum.
Doug.