Caterham Hayabusa Return to the Road

[u02rsb]

Back in 2006/7 I built a road legal Caterham 7 with a hayabusa engine and after going through a long process I got it through the SVA and had it road registered. I think I must have driven less than 100 miles on the road before I started to take part in local sprints and hill-climbs. After moving from the ACB10s to slicks and removing all extra road kit it became a pure race car only machine and went through extensive development over about 5 years. I've now moved on to a single seater for my racing but can't let go of my seven and so it has been sitting in the garage.

With the COVID lockdown I've had some extra time to spend in the garage and have decided to convert my car back to a road car.

First mod I have made is to the inlet which has involved moving to curved air inlet trumpets to reduce the overall height. I think I can get about 80 mm clearance under the dry sump now without cutting a hole in the bonnet. But I do need to change my tyres from the cross-ply slicks I currently have to radial road tyres to check.

2 questions I haven't really been able to find clear answers from searching Blatchat:

1. What ground clearance do you really need under the sump, I've read about coke cans, 70 mm - 100mm is there anything definitive before I get my engine frame revised?

2. What is the latest recommended tyre for fast road / track summer only driving? It will be 13" on Mike Barmby wheels. What width wheels are currently run?

I'm sure I'll have many more questions as I proceed and will provide photo updates whenever I've got something interesting completed ;) 

Thanks for any help,

Rob

  

 

 

  

 

[Wrightpayne]

Tyres - Toyo R888r's.

Keep us updated on progress!

I remember seeing the early pink Fireblade seven at Cadwell duelling with an R500K and they were evenly matched, but the howl and sequential clutchless gear changes were awesome! 

[u02rsb]

Thanks for the feedback on the Toyo R888r's .Any idea on wheel width I should have for a R500? I believe I ended up using the rears for the fronts and going super-wide on the back when I went for slicks which worked really well so I probably just need to know the standard wheel width of the R500 at the front. What is the largest I can use (front and rear)?

[Wrightpayne]

I seem to recall the R500 running 6.5 and 8.5 split rims. Many with single piece alloys run 6 & 8s with 185/60 fronts and 205/60 rears.

Having a mere 135bhp I just run 6x13 all round with 185/60 toyo's.

[ScottR400D]

I’d suggest 6”/8” rims with ZZRs assuming about 250bhp? 

I’m not saying the ZZRs are better or worse than the Toyos, but I’ve been quite impressed by them as long as it’s not too cold. 

[u02rsb]

I've just checked and my MB split rim wheels were 8.5" and 6.5" originally with ACB10s fitted which lines up with what Wrightpayne remembers. How do I work our what size Toyos / ZZRs will fit?

[Richard Price]

185/55-13 and 215/55-13 ZZS or ZZR are the normal sizes used on 6.5 (5" inner/1.5" outer) and 8.5 (6" inner/2.5" outer) MBs.

 

[SM25T]

Clearance under the sump ... should be measured with the equivalent of your weight in the car, or with passenger too if that's how you normally travel. The height you set depends on how much you value your engine, the state of the roads you travel on, the rating of road springs, etc. I have 300lb springs on the front dampers to help keep the sump off the road in high speed compressions.

[Wrightpayne]

Just advertised a set of headlights in marketplace if you're in need. Will have some brackets available shortly too.

Regards

Ian

[u02rsb]

Thanks for the offer Ian, I've still got all the road stuff (like lights). They are just a bit dusty being stored in the attic for 10 years :)