Radical SR8

Had a good day at Oulton Park last week as a bit of an end of season blowout.



Weather was just a touch damp on first session but soon cleared up to give a nice day. Everything going well, right upto the 4th session when revs started spiking in the higher gears...felt like clutch slipping. It happened a few times so came into the pits and clutch pedal just went to the floor, so had to stall it in the pit lane. Thought that the clutch had worn out, started slipping, and then just welded itself together. Let the car cool down and then the pedal seemed to come back and work again, but not worth the risk so called it a day. Car was about to come apart for winter refresh so not really any bother. Suspected clutch needed changing anyhow.

So stripped the car and as soon as got box off, there was signs of clutch fluid around the slave cylinder. Inside of bellhousing was wet, and when took clutch out, wet too. Looks like the slave piston seal/s have failed, spitting fluid on the clutch, slipping it, and pedal to the floor.

Clutch looks on the point of failure also though, not much material left on the plates.

So engine out and off for refresh and more ponies

Winter rebuild starts now.

 

Shame you didn't get a full day at your local track

You'll have put a new clutch pack in anyway with a extra 50 horses pushing the old girl along lol

Lots of pictures of your winter work please Rob

 

Engine dropped off at RLM Racing for inspection, and then to plan whats next

Larger capacity
Headwork
Valves
Cams

Yummy yummy yummy.

 

Saw a v8 in bits yesterday when I dropped my engine off and asked about these flywheel bolts. TSMD is the initials of the draughtsman who made the design drawing, POW is Powertec, and 027-A is the drawing number. When these v8s were first designed, they used fairly regular m8 bolts to hold the flywheel on, but there were some failures. These were subsequently designed and are custom made by a F1 supplier. Multiple use, and never known to have failed since. They look like a nice conrod bolt in design.



Also found out that the clutch slave cylinders are known to be a problem on these cars, with some of Euromasters cars having to change the seals over race weekend. Well that needs a modification then....

 

Inner seal on clutch slave piston totally goose'd. Looks like its been rolling against quite a sharp edge on the piston groove. Radical parts list now shows square section o-rings......hmm.......

 

Good chat with Radical parts dept today about clutch slave cylinder. They have an upgraded piston liike the one above that now takes square section seals rather than round section o-rings. These are much less prone to rolling and look a lot like those used with brake caliper pistons. Piston plus 2 seals on way to me now. Excellent service.

 

Clutch slave cylinder rebuilt with square section seals and new piston. Good to go again.



Clutch sent for inspection at Competition Supplies at Silverstone (the main UK Tilton place) - free inspection service and then they have the bits to replace anything thats worn out. Friction plates were still within wear spec, about 97 thou (limit is 89 thou, lost 2-3 thou only this year, but thats from an already well bedded in/ used clutch) but there were a few bits of material missing. Metal intermediate plates looked like they had gone past runout limit - as the centers get hotter than the outsides, they wear into a dish shape. Basket looks fine. Who knows if spring is still in spec.

Engine at RLM awaiting inspection and mods. Nothing more to be done presently apart from clean bits and bobs. Need to get the front floor off for replacement with one bought earlier this year but not starting that till rear is all back together again.

 

keep us updated!
Jon

 

Clutch back from Competition Supplies at Silverstone. Excellent service. So the SR8 has the following clutch bits

Cover/basket is Tilton Sport 5.5" 2 disk (p/n 67-902HG)
Friction plates are 5.5" 4 paddle / 6-rivet metallic with stacked hub configuration and 1"x23 spline centers (p/n 64140-3-AC-30)
Pressure plate is same as is used in more expensive OT-III clutch, 5.5" high ratio, (p/n 67-118HR)
Floater plate also used in OT-III, 5.5" standard (p/n 67-119).

 

Pictures pictures pictures

 

While the engine is out, opportunity to service the fuel regulator/ filter. Disconnected from car and removed blue cap to reveal a couple if o-rings and a paper filter. A bit of research showed that these filters are from Sytec, as used in their Bullet Motorsport Fuel Filters. Apparently, the paper elements filter to 8um and are good for 350hp. Doesnt sound right as mine already has more than that. Anyhow, also available is a high flow re-useable stainless filter, 55um, good for 'over 350hp'. Fitted a stainless one with two new o-rings.

 

Bit of an update, we had the Liverpool MC Speed Championships awards night at Liverpool Golf Club. Cracking night and ex-Top Gear presenter Steve Berry did the awards and speach. Funny bloke, and a genuine petrol head. Ended up taking to him about Vincent motorbikes. So I went up for my award and he said blimey....your tall....and then stood on his chair for the photos LOL.



Good end to racing year. For the first competitive year in the Radical, not a bad set of results at all. Massive highlight was first FTD, in the wet, at Anglesey British Sprint Champs round.



So engine has now been stripped and inspected and was in very good health. No major issues at all so could be rebuilt with new bearings, seals, chains, oil pump bits etc etc etc.

Alternatively we could breathe on it all a bit. Original idea was to go up to 2.9L with some 84mm pistons (+3mm) but to be on the safe side, this should be done with Gen 1 busa barrels as Gen 2's are very occasionally known to crack between the bores at +3mm. This is usually with nitrous or boosted motors, so its unlikely, but it could happen. So thats not a problem, move over to Gen 1 barrels, but then a story emerges that says Gen 2 barrels are better on SR8s as they work better with the oil system given they have cutouts at the bottom of the bores allowing gas pressure equalisation between the bores. These cutouts are what can cause the cracking when overboring a Gen 2 barrel too far. Gen 1 bores on a SR8 can lead to the oil building up in the heads and actually draining the oil tank into the breather catch tank. Not good. Unlikely on cars used for very short runs like hillclimb, but possible on anything 20/30mins run time. Hmm...dont want to compromise the possibility of doing longer runs, trackdays etc.

This explains more http://www.hayabusazone.com/crackedblocks.html

So right now, feel like sticking with Gen 2 barrels, which can still go +2mm totally safely, giving 2814cc. With some reprofiled cams, that could still be +50hp.

Decisions, decisions.

Might leave it as a stock 2.7 and develop elsewhere......

 

Probably do cams and maybe some other developments and stick with 2.7 L, atleast for now, as pistons and bores are still good....and upgrade to 83 mm bore in a next engine rebuilt

 

Reassembly underway:

 

Nice

 

great pic of inlet port angle....serious downdraft into cylinder!

 

Didn't notice that a the first glance!! Lovely!!

 

Is it a stock bike casting or a bespoke head?

 

stock bike head. this is the cool thing about this engine - a LOT of it is stock hayabusa. means big savings come rebuild time compared to race engines from the likes of NME, Judd etc.