unable to meet coupler tolerances

[Pablo]

I'm installing my engine yesterday and was unable to meet the front to back tolerance limit (2-4mm) for the midshaft/coupler on my SJ. The side to side tolerances were o.k. with shims, but I'm unable to get the engine coupler and midshaft coupler any closer than about 5-5.5 mm. My Climer's manual gave me the tolerances limits. Will this wear out the midshaft prematurely?
Additionally, should my midshaft have any "wiggle" to it at all? I'm guessing I can move it laterally a 1-2mm. It spins freely and I don't hear any bearing drag. I just gave it a fresh lube.

 

[Waternut]

Coupler wiggle is normal. Not sure on the spacing gap though.

 

[blaster800]

I'm installing my engine yesterday and was unable to meet the front to back tolerance limit (2-4mm) for the midshaft/coupler on my SJ. The side to side tolerances were o.k. with shims, but I'm unable to get the engine coupler and midshaft coupler any closer than about 5-5.5 mm. My Climer's manual gave me the tolerances limits. Will this wear out the midshaft prematurely?
Additionally, should my midshaft have any "wiggle" to it at all? I'm guessing I can move it laterally a 1-2mm. It spins freely and I don't hear any bearing drag. I just gave it a fresh lube.

If you install another washer between the midshaft and coupler you can gain some adjustment !!I would be more concerned side/side and up /down is on the money ... not saying this is correct, just sayin thats what i have done sucessfully in the past PS : Im running 2 washers now to keep gap within tolerences, with no issues . FWIW

 

[Pablo]

If you install another washer between the midshaft and coupler you can gain some adjustment !!I would be more concerned side/side and up /down is on the money ... not saying this is correct, just sayin thats what i have done sucessfully in the past PS : Im running 2 washers now to keep gap within tolerences, with no issues . FWIW

Do the washers go on the midshaft or the engine coupler side? It shouldn't matter I guess, but trying to figure this out. I appreciate the input.

 

[SuperJETT]

The midshaft is supposed to protrude out the back of the intermediate housing ~20mm, take it off and measure it. You might need to **whack** it a few times with a hammer (use something to protect the shaft) but really 5mm is good enough in my book.

 

[Pablo]

The midshaft is supposed to protrude out the back of the intermediate housing ~20mm, take it off and measure it. You might need to what it a few times but really 5mm is good enough in my book.

Que...no hablo?

 

[blaster800]

Do the washers go on the midshaft or the engine coupler side? It shouldn't matter I guess, but trying to figure this out. I appreciate the input.

I put mine on the midshaft coupler , by doing this I was able to use ''all'' of the'' hole circumference'' in the engine mount bolt holes to allow good side to side adjustment

 

[SuperJETT]

Que...no hablo?

I was messing with our 3 year old while typing that, fixed it.

 

[feartheride]

Yes it's likely the mid shaft got bumped back farther then it should be,for 5 mm ,I wouldn't worry about it

 

[keefer]

One little tail stab hitting bottom will cause the engine to bump the mid shaft back. Just do like SuperJett says and remove the midshaft assembly and use a hardwood block and a hammer to drive the shaft a little more towards the engine. If you have access to a press this will make the task very easy and you can make more accurate adjustments.

 

[blaster800]

My midshaft has a shoulder on it thats seats against the inner race of the midshaft bearing . If ithe midshaft is not suposed to be seated against the race then i assume the shoulder would not be there would it ?? if the shaft is not seated, then when the eng moves within its eng mount bounderies ''during a tail stab'' it will just push the shaft back against the bearing again , if its shouldered it will bounce against the bearing rubber hub and return to the exact spot it was at due to being shouldered ! not stiring the pot but thats how i see it . I just did this today ...... put an xtra washer between midshaft and coupler , my bearing was shouldered on the midshaft , and the eng mount bolts were EXACTLY in the middle of their holes allowing me to adjust my coupler clearance any direction I choose .... so if you stick the tailstab 'hard'' the midshaft wont move on you and go out of adjustment .. anyways this is the way I like to do mine .

 

[Polish jet pilot]

hammer it a bit in a vise. Did it and managed to align it. I guess this is a normal problem and normal solution.

 

[Carbon Blaster]

I know it's an unusual setup, but the midshaft doesn't get pressed in till the shoulder rests against the bearing. The rear of the shaft should sit 19.5mm - 20.5mm from the machined surface of the housing.
This measurement is designed to give the prop shaft spline about a 5mm gap before it bottoms out inside the midshaft spline.
If your chasing a 4mm gap between couplers, you can loosen engine mounts & tap them back towards the bulkhead (there is usually heaps of play with them) or put a washer in the end of the coupler before you screw it on the midshaft or crankshaft.
I would measure how far out the midshaft is protruding through the housing first. If it's too much, both splines will be bottoming out & loading up the bearings in your pump & will take away some of the flex that is meant to be in the midshaft & prematurely wear out other parts.
A 4mm gap is good to go for as it doesn't stress out anything & gives good surface contact which will make your rubber cushion last longer.

 

[blaster800]

I know it's an unusual setup, but the midshaft doesn't get pressed in till the shoulder rests against the bearing. The rear of the shaft should sit 19.5mm - 20.5mm from the machined surface of the housing.
This measurement is designed to give the prop shaft spline about a 5mm gap before it bottoms out inside the midshaft spline.
If your chasing a 4mm gap between couplers, you can loosen engine mounts & tap them back towards the bulkhead (there is usually heaps of play with them) or put a washer in the end of the coupler before you screw it on the midshaft or crankshaft.
I would measure how far out the midshaft is protruding through the housing first. If it's too much, both splines will be bottoming out & loading up the bearings in your pump & will take away some of the flex that is meant to be in the midshaft & prematurely wear out other parts.
A 4mm gap is good to go for as it doesn't stress out anything & gives good surface contact which will make your rubber cushion last longer.

Hey carbon , FWIW I have seen the center of a billet coupler bust out due to the midshaft not seating on the outer spacer washer of the coupler midshaft connection so i dont think putting a washer INSIDE is a good idea . I made that mistake once

 

[Carbon Blaster]

Hey carbon , FWIW I have seen the center of a billet coupler bust out due to the midshaft not seating on the outer spacer washer of the coupler midshaft connection so i dont think putting a washer INSIDE is a good idea . I made that mistake once

I worded it a bit weird, the washer/spacer that I was referring to is the washer between the coupler & the shaft. You can use a thicker washer to replace the original or just add a thinner one to bring the coupler forward.
But yes your spot on the money, it is important for the coupler to seat on the outer edge. Thanks for picking that up!