Tail Shaft Tolerance Looking For Some Advice

[Franko07]

Hi, im currently in the process of putting an rb25 into a cefiro and ive finished mounting the engine and box and am onto the tail shaft. The shaft i believe is the original rb20 shaft and i have pressed out the rb20 yolk and replaced it with the larger 25 one. The one in the picture is out of a VL (what my engine came out of) as the cup sizes are different just using it to mock up for now untill i get a r33 one.

What i want to know is if this distance is acceptable? Is there a min max distance for tail shaft float? Its roughly sticking out 25mm before being hard against the box. Car is being used for drifting. Would be a real pain in the ass to have to get a one peice made up for 20mm too short...thanks

[Dobz]

Not sure on factory tolerances and I cant remember how far in the bush goes which keeps the yoke centred. If you can find out how far in the bush goes then that would give you a good starting point, maybe some wire with a little hook to feel where the back of the bush is and mark the wire to get the length. I would imagine best case would be to have the yoke fully supported by the bush at least.

[Franko07]

Thanks for the reply . By the bush do you mean the splined part of the tailshaft? As theres no real bushing as such just the outer seal and the output shaft? The splined part is about three quarters in and the seal actually stops on an old wear mark. May be its the fact that the metal sheild is missing from the outside of the box that makes the shaft look further out than it really is...?

[GTRPSI]

Do Cefiros have a floating diff or is it fixed into a subframe?

Point being is you need some clearance in a floating diff setup as the driveshaft moves in and out however in a subframe mounted diff setup there is no (almost no) diff movement, in these cases best to follow the old seal wear pattern on the yoke.

Its possible to make a machined billet spacer to fit on the diff side and use longer bolts to push the tailshaft forwards if need be however the most reliable way would be to get a longer tailshaft made up.

[Dobz]

There is an outer bush inside the housing further in past the seal where the yoke sleeves into. As GTRPSI mentioned if there is a wear mark on the yoke follow that and if it lines up with the seal you should be alright.

[iruvyouskyrine]

Its possible to make a machined billet spacer to fit on the diff side and use longer bolts to push the tailshaft forwards if need be however the most reliable way would be to get a longer tailshaft made up.

Nope as cefiros use a centre bearing in the tail shaft.

I have a 25 box behind my 25/30 and my tail shaft has about as much engagement on the splines as yours. Sticks out further than I would like but it's still acceptable in my option. Has held up well for 2 years of huge clutch dumps/kicks from drifting. You will be fine with how it is currently.

And about the dust cover, yes it is a bit of trickery. If you took a dust cover off a standard car you would find there is at least 10mm of the tail shaft protruding from the end of the box.

Edited July 19, 2015 by iruvyouskyrine

[Franko07]

No worries thanks for the replies has been helpful!