750/850 fd swap trouble!!??

[Big Beadle]

HI everybody this is my first post so bear with me.
So this eve when i got out of work I started the FD swap,Took the 22mm nut off,pulled the coupling off,cleaned every thing with carb/choke cleaner,and filled the oil holes with RTV,put the 1/2 inch washer in and "attempted" to torque to spec 72-108 FT LB. I could not even get passed 20 ft lb before the thing started to jamb-up,so i took the new washer out and tried to go back with the stock one and attempted it again, with no luck. So i stripped the thing apart everything looks good inside. This FD is off a 1980 XS850 so its a type-2 with the phillips head screw. I checked the final drive manual the one of the members had posted and tried to make sense of it???. When i took the nut off i did so with an impact gun it seemed to be on there decent enough,I spent six hours fiddleing with this thing. I even tried to crush the crush sleve more but no go, the nut stripped out at less than 115 ft lbs it did not seem rite to me at all can some one help me out with this Plz!!:
I have done the rear diff in my 01 dakota twice and it has the same set-up with the crush collar. I think the collar is done-for and in need of a new one along with the nut? The fd looks like it has no miles on it at all no mars or scars on the internals.


79 XS11 SPECIAL
4-1 kirker
K&N air PODS
GM HO COILS-with-accel 8.8mm wires
T.C's. SOFA
FD swap SOON!!
XJ AIR RIDE

[BA80]

First Beadle, silicone is not the right stuff to use to block the holes, you need to use a hardening gasket maker like the old permatex gasket maker. You know, the stuff you needed a hammer and chisel to remove?

And you NEED to use the recommended washer. I actually used both the replacement AND the stock washer on mine. The stock one on top of the replacement.

The torque spec given is for a NEW crush sleeve. Get a new lock nut (yours is stripped right?) and go ahead and use the impact wrench and snug it a little at a time until you feel slight resistance when you turn the coupler. The resistance should be about 20 or 30 inch pounds.

I've had mine in for about 2 years and 30K miles and it's still working great.

I personally recommend 75w140 synthetic gear oil in both the final and middle drives also. They'll run much quieter and cooler

[cywelchjr]

HI everybody this is my first post so bear with me.
So this eve when i got out of work I started the FD swap,Took the 22mm nut off,pulled the coupling off,cleaned every thing with carb/choke cleaner,and filled the oil holes with RTV,put the 1/2 inch washer in and "attempted" to torque to spec 72-108 FT LB. I could not even get passed 20 ft lb before the thing started to jamb-up,so i took the new washer out and tried to go back with the stock one and attempted it again, with no luck. So i stripped the thing apart everything looks good inside. This FD is off a 1980 XS850 so its a type-2 with the phillips head screw. I checked the final drive manual the one of the members had posted and tried to make sense of it???. When i took the nut off i did so with an impact gun it seemed to be on there decent enough,I spent six hours fiddleing with this thing. I even tried to crush the crush sleve more but no go, the nut stripped out at less than 115 ft lbs it did not seem rite to me at all can some one help me out with this Plz!!:
I have done the rear diff in my 01 dakota twice and it has the same set-up with the crush collar. I think the collar is done-for and in need of a new one along with the nut? The fd looks like it has no miles on it at all no mars or scars on the internals.


79 XS11 SPECIAL
4-1 kirker
K&N air PODS
GM HO COILS-with-accel 8.8mm wires
T.C's. SOFA
FD swap SOON!!
XJ AIR RIDE

That high torque spec if for the type 1 FD. The type II uses the crush sleeve to set the pre-load and the torque is MUCH lower and if your not redoing it you should be just bringing it up decently snug. RTV will work just fine there thought, it's what the tech tip calls for and all, but you DO need to make sure it get time to fully cure before you reassemble it.

[BA80]

Like Cy said, the silicone will PROBABLY be fine but I prefer the hardening kind in this application.

Here is the ORIGINAL FD swap post by Maximan and xschop.

[cywelchjr]

Like Cy said, the silicone will PROBABLY be fine but I prefer the hardening kind in this application.

Here is the ORIGINAL FD swap post by Maximan and xschop.

I used the same RTV I used to seal the SOFA unit to the engine. If it will keep that sealed with pressurized oil against it, it will work just find with unpressurized gear oil without any trouble. It's high temp too, so I'm not worried about temp problems. This is one place I wouldn't use yamabond or 3bond though, it's not the right kind of machined surface IMHO.

[BA80]

Dammit Cy! I'm not arguing so quit trying. I was just stating a preference.

In my opinion silicone is not he right choice because it can distort at the high RPMs the driveshaft turns. You know, centrifugal force.

After all, this IS the kind of thing I do for a living.

[mxmikie]

yea silicone is cool

[cywelchjr]

Ok, I guess that could be a good point. I'm not sure how it can distort in those little holes under that big washer being held under pressure. That said, I did consider how one might affix an oil seal to the drive shaft so you could use the FD unmodified and let it lubricate through the little holes like it does on the 750/850. Then this would be a moot point, but we would have to find a seal that would mount to the shaft and fit into the FD housing properly. Not sure which would be better however, and frankly I think that the method each of us prefers would probably work fine, but dammit, why didn't you tell me this BEFORE I did the FD mod?

[MidniteSpec]

Just a shout out, to say did the FD swap this past weekend. Not looking for another gear anymore, and went together smooth. Great info and step by step. Thanks to all the contributers.

[Big Beadle]

Thanks

Thanks everyone,The RTV was the (Right Stuff One Minute Set From Auto Zone) Ill get a new nut from the hardware store and give it a go. I did hit it with a impact to sugg it up and it did seem fine (PRELOAD) but i wanted to make sure it was corect torqe specs That makes sense on The new crush sleve for that high of a number, The xs11 Fd was @ 70 ft lbs I took that nut off and on afew times also and it dont bind at 70 ft lbs and the 850 fd does?????? SO Just snug it with the impact and its fine???? ill try it And i did use the right washer A regular 1/2 inch WIde hole grade 8 washer it covered the holes as (TT) stated TY EVERYONE!!!!

[DGXSER]

The RTV works just fine, and the right stuff is good for this. Alot of miles by more than a few folks has proven out the RTV with no leaks or issues.

As for torquing the nut, I had this exact same issue when I did my first one. I never went as hog wild as you did, I found that after I hit something like 40 ft-lbs I could no longer spin the drive. The advice I got from many members here was to simply mount the FD on the wheel (off the bike) use something to keep it from spinning and torque the nut until I got to the correct pre-load, which for the type II is something like 4 ft lbs. Meaning it takes 4 ft-lbs of force to spin the drive.

The type I drives used a washer/spacer to set the preload of the pinion, so those type drives, the correct spacer in there may be important. I've not had one myself and seen how it is assembled to determine if replacing it after the fact would impact anything. But reality is you HAVE to put the larger washer in to cover the oil galley holes. So unless your going to machine that washer to the exact thickness of the factory spacer/washer, which the tech tip never spoke of, and ALOT of these FDs have been fitted to the bikes from that tech tip, It is a moot point.

On the type II, they used the crush sleeve, so the washer that is in there from the factory is just a washer, replace it at will, with whatever. Put the RTV in the holes, and on the type II I like to put a ring of it around where the coupling meets the output shaft as well, then light coat on the washer and put it in place.

[James England]

RTV is fine for the holes. I actually used 335 'Construction Grade' silicone bathroom sealer....technically it's called 'low modulus' which means it's pretty solid stuff when cured....more so than normal bathroom silicone.

[bikerphil]

I always use threadlock blue on that pinion shaft nut for peace of mind.