XS750FD. Safe? Unsafe?

[Bonz]

Hey Scott,

Up burning the midnight oil, eh?

Simple question for ya'... Can that support collar be transferred easily, or not an option?

I wish I'd looked at my FD when I put it on. What's the way to tell if it's a type I or II, if that is possible from the outside, i.e. serial number or something on the FD housing itself?

[cywelchjr]

Hey Scott,

Up burning the midnight oil, eh?

Simple question for ya'... Can that support collar be transferred easily, or not an option?

I wish I'd looked at my FD when I put it on. What's the way to tell if it's a type I or II, if that is possible from the outside, i.e. serial number or something on the FD housing itself?

Type 2 has the Phillips screw that holds the pinion assy to the housing, the type 1 doesn't. You need to be able to identify them when you install them because the preload setup is different for the two drives, and doing it wrong can kill the drive. Mine is a type 2, but I don't know if I have the collar or not, I didn't know to look for it. Next time I pull the rear wheel I'll check it though, cause maybe what we have here is a 750 FD that will handle the load, and one that won't so well. I can hope I have the good one, if not I'll look for a good one for the next one.

[Bonz]

Nice observation Scott, and thanks Cy, I'll know what to look for when I pull the wheel, at least in terms of the support collar, which may be the keystone in all of this.

[3Phase]

'Bones, we should have swapped bikes in Colorado!

Taking Roo's bobber for a spin was a hoot but we should have tested the difference the 750 final drive ratio makes on a Standard with a tall touring tire on a 17" rim and a Special with a (regular?) tire and 16" rim.

Next time... if I can remember!

[3Phase]

Okay, I got a flashlight and went out to take a quick look at the two final drives. It looks like the support collar is pressed into the XS1100 ring gear hub but I can't tell if it's spot-welded in place.

It looks like the hole in the 750 ring gear hub might be too small or just not machined for a collar but tomorrow I'll take a better look and see if it can be done without too much angst or a lot of drama.

[jwhughes3]

riding high behind me...

so howard maybe thats why in all ray's pics he is last behind me with a quarter mile between us - he was getting too high on the fumes!

I will try rejetting perhaps on next trip to colorado or maybe bring a spare bank of carbs for over 5000' elevations

john

[James England]

Catch 22

Well Folks. I swapped drives back to OEM last night and have just come back from a burn through the countryside. The OEM drive definitely has more of a 'muscle bike' feel to it (without abusing the bike) on acceleration but....it's the rev thing again at over 60mph. A real Catch 22.

It only took 45 minutes to change the drive last night, so I think I'll run both drives and put the 750FD on for touring and run the OEM FD for the local runs round the countryside.

I still feel "exuberant" about the 750FD swap though. So much so, I just bought a second 750FD...... the two of them should be good for 80,000 careful miles? And the OEM for exuberant local runs.......

[Bonz]

Scott,

You know, with all the hub-bub going around about street performance with the FD swap, I think the Special is the one that benefits most from a performance perspective because of the 16" tire. I have a Dunlop 491 on the rear. Flat tread profile relative to most of the other bikes I saw at the rally, but dang, the thing has over 5,000 miles on it and still a measured 5.2 mm of tread. Can't beat that, although I checked chicken strips after the mountain ride, and mine were about 1/8", and most other guys have 1/4" or more and we were all "railing" around corners the same. I don't have much more to go before you'd be picking me up off the road.

I rode CaptonZap's Standard once before we both did the FD swap, and it was turning 200-250 rpm lower than my special at around 60 mph. I went down 400 rpm at 60 mph with the FD swap, so I'm sure his rpm dropped by a similar amount.

I was happy as a clam with the way my FD swap fit that trip to a "T" for the Colo Rally. Kept my rpm around 4k on the open road with Zap and George coming to the rally, allowed easy pulling through the mountains or a downshift for a burst. Changed my FD and MD fluids just before the Rally, so I'll pull the rear plug after a ride this weekend and take a look at the condition, look for any wear signs, etc. Mobil 1 75w-90 , for what it's worth.

If I had a Standard with the FD swap, my instinct is it would have needed a bit more use of 4th gear whereas I could run the Special in 5th at 3,000 rpm at a GPS 50 mph and feel it was doing fine. Lower speeds than that I was in 4th going up the hills. The XS doesn't wake up until 3k rpm anyway...

[DAVINCI]

YAAAWWWNNN

[cywelchjr]

Scott,

You know, with all the hub-bub going around about street performance with the FD swap, I think the Special is the one that benefits most from a performance perspective because of the 16" tire. I have a Dunlop 491 on the rear. Flat tread profile relative to most of the other bikes I saw at the rally, but dang, the thing has over 5,000 miles on it and still a measured 5.2 mm of tread. Can't beat that, although I checked chicken strips after the mountain ride, and mine were about 1/8", and most other guys have 1/4" or more and we were all "railing" around corners the same. I don't have much more to go before you'd be picking me up off the road.

I rode CaptonZap's Standard once before we both did the FD swap, and it was turning 200-250 rpm lower than my special at around 60 mph. I went down 400 rpm at 60 mph with the FD swap, so I'm sure his rpm dropped by a similar amount.

I was happy as a clam with the way my FD swap fit that trip to a "T" for the Colo Rally. Kept my rpm around 4k on the open road with Zap and George coming to the rally, allowed easy pulling through the mountains or a downshift for a burst. Changed my FD and MD fluids just before the Rally, so I'll pull the rear plug after a ride this weekend and take a look at the condition, look for any wear signs, etc. Mobil 1 75w-90 , for what it's worth.

If I had a Standard with the FD swap, my instinct is it would have needed a bit more use of 4th gear whereas I could run the Special in 5th at 3,000 rpm at a GPS 50 mph and feel it was doing fine. Lower speeds than that I was in 4th going up the hills. The XS doesn't wake up until 3k rpm anyway...

For me on my standard 3k is a GPS 55MPH, any lower than that and I have to drop to 4th, but I generally don't hit 5th till about 60 anyways. Next time I get an excuse, I'll pull the FD and check for the collar on mine, to see if I have one, it sounds like that might make the difference between one that can be flogged and one that can't (or at least won't last as long if you do). My guess is that the collar was added to increase the strength of the FD, so all the FD's made after the 850 came out would likely have the collar, as it would not make sense for Yamaha to make two slightly different FD's for the two bikes, just make them the same, there might even be a slightly different part number between the early version of the type II and the later.

The only thing I wish, is that you could use the modified drive shaft with the stock FD, it would make switching back and forth easier.

I still think that specials will get longer life with EITHER style FD because of the smaller rear tire, just less stress on the FD.

[3Phase]

I checked the drives and the support collar is part of the axle tube, it's not a separate part.

The ring gear hub has to be made for the axle tube with the support collar to do any good so swapping the axle tubes around won't really do anything useful unless you're bored or just need to hammer on something.

[3Phase]

The only thing I wish, is that you could use the modified drive shaft with the stock FD, it would make switching back and forth easier.

What did you have to modify on the drive shaft, Cy? Or are you talking about removing the drive shaft to take off the spacer and fishing the drive shaft back up into the u-joint yoke?

I still think that specials will get longer life with EITHER style FD because of the smaller rear tire, just less stress on the FD.

That's what my gut tells me but I'll have to test it for myself and get some pictures before I can say for sure one way or another.

Fortunately for me I just happen to have a '79 Special so after I get another 750/850 final drive I can do the inspection and installation photos, then do the writeup myself.

[cywelchjr]

What did you have to modify on the drive shaft, Cy? Or are you talking about removing the drive shaft to take off the spacer and fishing the drive shaft back up into the u-joint yoke?

Yup, that's what I'm talking about. It would be nice if you could use the shaft with the spacer with the 11's stock FD so you could just swap without having to swap driveshafts each time (I have the original and the on with the spacer RTVd into place, so rather than remove the spacer I'll just swap shafts, but it would be nice not to need to do that. But I know that's just wishing for too much, cause I don't think the stock FD would handle the shaft being shoved that far up into it . I don't think it would like it, I don't think so at all .

[Larrym]

Food for the ears?

Fortunately for me I just happen to have a '79 Special so after I get another 750/850 final drive I can do the inspection and installation photos, then do the writeup myself.

And another Video from your cell phone if you can, please??

I just love the fact that your video showed the difference between the good/bad drives in the AUDIO track.

[3Phase]

And another Video from your cell phone if you can, please??

I just love the fact that your video showed the difference between the good/bad drives in the AUDIO track.

Definitely. Bad bearings look just like good bearings so you can do all the by-the-book setup with fancy wrenches and fixtures and make pretty contact patterns on the gears until the paint fumes make you dizzy but if it makes funny noises it's not going to work for very long no matter how well-adjusted it is.