Type 4 Centre main and flange crank questions....

[leec]

I have a raised roof Ali case that is part of my new FK89, ti valves comp eliminator 2276cc motor I was going to have built soon.
The spec of the motor has changed massively from the original spec and now will be a race motor.

The crank and flywheel I originally purchased was a CB Performance super race crank and forged flywheel. I am not sure this will be up to the plans I have in mind any more . 230 BHP then maybe some gas later

I have an opportunity to buy an 84mm Bugpack Flanged crank, with type 4 centre main only. Is this crank a better option and worth the extra work my case will need? I have heard an adapter bearing is available for the type 4 centre?

Any thoughts?
Lee

[MeXX]

Dear lee

I think it's not necessary to have a T4 center an 82mm stroke; but it's definitely better on everyting above 84mm stroke.

The bearing are easily to get (Scat) ore OEM BMW.
In my opinion it will be definitely better but I can't say it it's worth the money and the additional work.

Basically I would to it.


MeXX

[Udo]

Yes the adapter bearing works fine , and if you have  type1 thrust bearing and std case you can use the original KS spilt bearings. Avaliable at my shop or CSP

Udo

[leec]

Yes the adapter bearing works fine , and if you have  type1 thrust bearing and std case you can use the original KS spilt bearings. Avaliable at my shop or CSP

Udo

Hi MeXX, thank you for you reply.
Hi Udo,
Can you explain the above, do you mean I wouldn't need to machine the flywheel end of the case either?
Lee

[K-Roc]

Hi you still need to machine the end of the case to accept the larger seal used on a flanged crank, but you dont have to touch the main journals.

Cheers

[MeXX]

[Hi MeXX, thank you for you reply.
Hi Udo,
Can you explain the above, do you mean I wouldn't need to machine the flywheel end of the case either?
Lee

Dear Lee

The flywheel seal has an outer diameter from 4" (101,6mm) and you have to machine the case to accept this seal.
But this is the only modification you have to do. Main bearings are OEM split bearings from KS and center bearing is OEM BMW.

MeXX

[Jonny Grigg]

Jack Sacchette sells the T1-T4 centre main- have a look on his website.

The flange seal is bigger than the normal flywheel oil seal, therefore you have to machine the seal orifice in the back of the case to accept the bigger seal- it is pretty easy. I also made up a retaining plate that screws over the seal to prevent it blowing out.

Obviously you'll also need a flywheel to match the flange crank, along with the bolts- it should fit directly without any machining.