Buku clutch with crankcase refill cap
 

Some pics of the Buku clutch with the refill crankcase cap closed by an O-ring.
You can clearly see the small hole on the edge of the cap. On the other side is a hole as well to squeeze out the old grease. Cap should be sealed on the crankcase with any high temp plastic / metal sealant.
https://cimg0.ibsrv.net/gimg/www.rct...f2f324c81a.jpg

https://cimg1.ibsrv.net/gimg/www.rct...e5398f8877.jpg

Looking good. It's a great clutch. Do they allow you to change the clutch in your local rules now?

Dan...who do you mean with "they"? Do you mean the Serpent guys who have done everything using their incompetence to screw up this initial GT year?...I reckon you mean them:):)
Well we've started our own GT class accepting all brands using the basic rules of Roar / Ifmar with a restriction on engine, manifold, muffler and tyres.....Same brand, same type.

As far as the RTR series from serpent concerned after 1 year of races where nobody from serpent showed up or helped the class develop they are testing the huge caster problem to come to the conclusion it's the expensive tyres who have no grip. The good thing is they finally do something. Lets see what they will bring next year from an organisation and communication point of view.

By they I meant the local governing body in your country. I don't really think it is Serpents fault however they were pushing the RTR as the correct class for GT and I still don't understand why they were against using the race chassis instead of the RTR which surely was designed for parking lot racers! As I mentioned before I personally don't agree with the RTR class. In the UK we only have 2 or 3 cars now and I'm pretty sure by the start of next season it will be none. All will convert over to the RACE 'modified' chassis class. We will be starting the UK's 3rd year for the GT class next March.

The ROAR/IFMAR/EFRA rules are great. It works very well and we run to the same under the UK BRCA rules. Good news that you've started a class which runs the same so that if you go to any Euro champs race you'll be running at the correct level.

In fact with the RTR class you end up changing so many parts due to wear and tear notwithstanding the standard RTR clutch! The Buku will last almost for a lifetime! Actually I think the Serpent 4-shoe clutch 4x yellow with X-Hard springs is ultimately better and faster over a lap it's longevity is no where near the BUKU.

Installation update > Crankcase caps needed to be removed
 

Bit of playing around with the IGT8 allow clutch bell with 4 bearings, crankcase cap and Buku clutch. I found out the crankcase cap eats up a fraction too much space on the crank in order to be able to tighten the clutch bell nut without squeezing the bearings. For now I removed the crankcase cap as you can see on the vid with more then enough clutch bell play to shim it back to approx 0.5 mm.
I could do with only 3 clutch bell bearings as most of the GT's are only running 2 I believe. Using the TKO black and blue seal clutch bell bearings this is an option in order to be able to use the crankcase cap.....

+ https://youtu.be/BV_wO4E_Qcs" title="View this video at YouTube in a new window or tab" target="_blank">YouTube Video

https://cimg7.ibsrv.net/gimg/www.rct...21e760687c.jpg

https://cimg8.ibsrv.net/gimg/www.rct...fcb6f74438.jpg

https://cimg9.ibsrv.net/gimg/www.rct...8b605be5e4.jpg

https://cimg0.ibsrv.net/gimg/www.rct...7ec9915a4f.jpg

https://cimg1.ibsrv.net/gimg/www.rct...50ce567a3c.jpg

https://cimg2.ibsrv.net/gimg/www.rct...e0ebad7ca7.jpg

To be honest I'd only think about bothering with the crankcase cap in off road to keep the dust/dirt out the front bearing. It isn't really useful in on road racing and as you've found there isn't really the room to mount it anyway.

If you need the cap to get the engine stable then there is something else wrong. It might be the front bearing has an issue or whatever but as I've said before the XRDs are not the most stable of engines anyway.

Is that an aluminium end bell? If it is it won't last very long with the buku komposite shoes!

@ Dan, a remark on what you mentioned which is true off course,

If you need the cap to get the engine stable then there is something else wrong. It might be the front bearing has an issue or whatever but as I've said before the XRDs are not the most stable of engines anyway.

What I noticed with my onroad nitro engines in the 8th class, when I used a similar BUKU solution is the following, My discarded worn nitro engine(picco and nova) which didn`t idle anymore and had erratic tuning problems, after this modification was idling very good and best of all was holding its tune for ever!. Both engine`s had this result. I know its had to do with the front bearing sealing, but both bearings were relatively new and already replaced with an offroad, one rubber sealed.

Just sharing

Are you using a one side seal bearing or a 2 side seal?
Most engine bearings are only sealed at one side so you can try a 2-side sealed bearing.

But normally the construction with the groove in the crankcase and crankshaft should build up an hydrolic seal. Problem could be that today's fuels with less oils and also thin oils make the working of the hydrolic seal much worse. In the past we were used to run metal sealded bearings which are open.

Guys,...thx for all the expertise! I really appreciated it. The front bearing is a ceramic one from TKO which had 2 seals. I removed the inner one for lubrication purposes but maybe this was not neccessary. I had the crankcase cap on nicely sealed with a high temp sealant but it wasn't to be from crankshat distance point of view. I still could try using only 3 bearings instead of 4 leaving plenty of space to shim the clutch bell. Will try this first and see how it goes. It has to be said, the 4 bearing clutch bell has virtually no radial play and feels smooth as a whistle.

w

You can also try the Serpent clutch crankshaft extension part from the 3.0 GT clutch which will make the crankshaft effectively longer so you may then be able to fit the crankcase cap?

Im already using the IGT8 extension which has lenght equal to 2 bearing widths. That extension is a fair bit longer then the serpent extension so no option Im afraid. Basically I only need a shim between 0,5 and 1 mm to be put inbetween the extension and the crank. But it has to be a shim with an outer dia of exactly the crank's dia.

w.

No problem to make.....

Gaat het om de 3x5 ?

https://www.amainhobbies.com/kyosho-...kyo96641/p3868

Outer dia crankshaft is 5 mm and the inner should be 3 mm to allow the clutch bell screw to slide through.

w.

As you can see these shims can be bought, also Ofna has several clutch shimm sets:
https://www.amainhobbies.com/ofna-1-...ofn10410/p2940

But I have all kind of machines at home and it is no problem to make some....