Final Drive Swap Poll

[rpgoerlich]

Just finished with the FD swap on my Venturer today. 750 FD was used as I had one on the shelf for the past year. After replacing the clutch, rear tire and the FD , I really didn't notice much difference on take off. RPM's dropped from 4k@60mph to around 3.3k@60mph.

Will see how it performs next week to and from work(60mi). Have been getting 31mpg with 50% city/hwy. Hwy speeds typically around 70mph on the HOV with city speeds at 35mph.

[Pat Kelly]

I swapped FD on the E as it's the daily driver / tourer/ workhorse.
The LG is the quick hotrod so will keep the stock FD

[James England]

FD off

Here's an update on the FD swap so far. I haven't received the new FD from Germany yet but, since I'll be working all next week and have no chance to take the bike out, I thought I'd get the OEM FD off etc in advance of receiving the XS750FD.

It took no more than half an hour. I removed the seat and lifted the rear fender. Then removed the lift handle and rear shocks after chocking up the wheel. Then I used a piece of thin rope to lift the swinging arm and hold it right up above horizontal.

Wheel off, FD off and then I used a small pipe wrench on the drive shaft and just gave it a firm pull and out it came. I didn't need a puller or slide hammer or anything.

I've removed the circlip and will get the 3/4 copper bit tomorrow . I already have the O rings.

This stage of the proceedings is extremely easy and really quickly done........... even if switching the FD isn't to my taste, it'll be easy enough to reverse it all and put the OEM FD back on.......

More later as the job progresses!

[Bonz]

Not sure I follow how this poll is "skewed"?

The choice "NOT DONE IT" doesn't play in this survey for the info being sought. Sorry! Many owners (many who have done the swap, many who have not) were involved in the recent threads discussing the FD swap, and their explanations/reasons for doing it/ not
doing it were presented well, so this poll is to find out from people with actual experience with the swap. Otherwise, it's just a campfire talk about theoreticals.

This poll is to see which bike, Special or Standard, has been modded the most (to get a ratio), and to find out if the mod obtained the results each rider wanted for their bike, thus the options to vote if the bike was switched back to the stock FD. The poll and subsequent observations are aimed at owners of bikes that have real experience with the swap, so anyone who hasn't done it would simply have opinion, not experience.

By looking at what's been voted on so far, one rider has swapped back, and the reason was that rider doesn't go above 50-60 mph most of the time, so the FD swap doesn't make sense, and I wouldn't do it either if that was what most of my riding entailed.

My 250 miles of riding with the FD swap tells me that I'm going to get a 2 mpg improvement in gas mileage, and 60 mph in 5th gear (on my Special) is right on the edge of where the engine starts hitting it's stride, so it does not roll-on as well at that speed. However, 4th gear at 60 mph with the FD swap is showing 4100 rpm, which is 100 rpm higher than 5th gear with the stock FD. When I'm running the back roads, per se, I just use 4th now. To me, that's a wash at worst and a benefit overall because I haven't lost one bit of performance when I'm in the correct gear for conditions, and gained a lot of versatility for higher legal speeds where I live, pure and simple.

Once the bike is wound up at 4700 rpm at 75 mph now (vs 5200 rpm at 75 before the swap) my seat of the pants tells me any performance change will be minimal for 95% or more of most riders.

I live in Colorado, at 7000 feet of elevation, so I live with mountains, I don't just take a trip trough them once in a while. If I need more giddy-up, I'll shift gears and be done with it. Seems like shifting is a 4 letter word to some riders, and not shifting the bike when encountering different terrain/elevations is a badge of honor. If keeping the stock FD makes those folks happy, that's what it's all about in the end.

[James England]

I looked around my shed and found a piece of steel pipe 22mm ID. It's thicker than copper plumbing tube and obviously harder than copper, although I don't know if this is actually an issue or not with this modification? I sawed a 16mm piece off:



then chemically removed the surface corrosion:



and then zinc plated it for about an hour:



I've used three O rings on the drive shaft, under the steel tube, mainly because I had enough of them and three of them fit the entire area that's recessed. I think they will help hold the steel tube firmly, although it is a good fit on the splined part of the shaft:



Then I put the metal tube on and put an O ring on the shaft:




Looking at the results, I think that three O rings holds it more firmly than one, over a larger area (I tried 1, 2 and 3 rings). The zincplating of the steel tube will resist rusting.

At the FD end of the shaft there is the spring which pushes the drive shaft towards the front of the bike. I assume that this spring will transmit force which is then borned by the single rubber O ring and steel tube? So, as someone has pointed out, whilst there is no way the shaft can come out of the UJ joint, the spring will push the drive shaft forward, won't it? Having said that, it doesn't look to me as if there is much possibility of wear at the joint of the O ring/steel tube and the UJ joint..... any more than there is wear on the shoulder of the splined front part of the drive shaft on the usual setup. Which means the drive shaft will stay correctly located at the rear end. This looks critical to me because the teeth on the drive shaft all have a very slight curvature to them when viewed from the side and the drive pinion of the FD meshes bang in the middle of each tooth:




Any comments anyone? Am I making any glaringly obvious mistakes or messing up somehow?

[Bonz]

JamesEngland,

It looks like you are doing well in terms of everything you have shared, done or observed.

CaptonZap who did his FD a few weeks before mine, used a steel spacer as well.

My 750 FD had already been converted by the previous owner (selling his stuff, gettting out of riding, but otherwise he liked the FD swap overall) and he sent me his copper spacer with the FD housing. According to him it had been in for at least a few thousand miles or more (can't remember exactly) and the copper spacer showed no signs of end-wear what-so-ever. Meaning that the spacer does not take much if any load from the spring pushing forward from the FD end of the shaft, and I even used the o-ring he sent as well, which had no wear on it.

I cleaned the driveshaft thoroughly and put an appropriate amount of silione/gasket sealer on the drive shaft and slid the spacer over it, that should hold it in place just fine, and only used one o-ring to "hold" the spacer in place from the end. I think that makes sense in terms of the explanation of what I did...

Those splines that are curved as you have so carefully noticed are there because as the driveshaft articulates with the swingarm, that small radius or curvature allows the splines to "roll" just a bit up or down (like a see-saw, per se) in the engagement splines on the FD housing. That way the u-joint isn't the only thing keeping things lined up when the swingarm moves. The best way I can describe it is that the slight curves allow the final bit of "fine tuning" with each and every suspension movement to make the system as smooth as it is.

[James England]

Gotcha. That makes sense. I have a question..... I suspect that my XS750 FD will arrive without the driveshaft spring. It wasn't in the photo on eBay. Will I be able to borrow the one from my XS1100 FD?

[bikerphil]

Yes, use the 11 spring, it will provide more pressure than the 750 spring.

[Bonz]

Yes, what bikerphil said. The 1100 spring will work fine and is longer than the 750 spring, so as he said it will provide more forward pressure, for what it's worth.

[James England]

Thanks. I'll do that. I think it will take me longer to make the XS750 FD look presentable than to do the whole fitting job. I'm going to strip the paint off it and use a US product called 'Prime-It' (anyone heard of it?) which I was given. Then paint it metallic silver as near as possible to the original colour. The Prime-It is supposed to be good for metal and is a weird creamy coloured liquid..........

I'm sure doing the above, and waiting for it to dry, will take longer than the rest of the job.

I'm really looking forward to getting the FD swapped and.... I promise...... I intend to give an objective, impartial, unemotional REPORT on what the bike feels like with it on. If it's not suitable for me, then I'll be removing it and putting the OEM one back on. I'm hoping I love it though, as the poll results would tend to indicate?

Looking at the poll, I must say, it doesn't looked skewed. As I understand it, the point of the poll is to establish what people think of the results having done the swap.... right? Having a 750FD in a drawer and not trying it on the bike really isn't relevant and it doesn't screw the poll by it not asking the question "do you have a 750 FD which you have never used?" Looking at the results, there appears to be a very high incidence of people swapping the FD and not swapping back. It's been suggested that people may have done the swap, not been happy but NOT swapped back (because of the 'work' involved). Having done today what I've posted, I must say that it's not at all hard and I think most people who did the swap and weren't happy would swap back, rather than ride a bike for what might be years, with an unsatisfactory FD, just to avoid an hour to fix it. I certainly would. Therefore, looking at the poll, most of the swappers must be happy with the results. That's encouraging. Time will tell for me though.....

[Bonz]

Well said from over the pond, JamesEngland!

Appreciate the open mindedness about it all, and I would swap back knowing what I've already discovered myself from the swap if I was in a situation that Tinman905 was in, and never ran my bike above 62 mph/100km/hr.

[James England]

I'm really hoping that I like it though! That's un-scientific but I really have been fed up with the 'high' revs and the engine feeling (IMO) slightly unhappy at 70mph. If the FD swap works out for me, I'll be really pleased. Having said that, if it's not for me, I'll definitely say and explain why.

I'm looking forward to doing the swap and seeing for myself what it's like.... either way.....

[skids]

I used bronze and coated it with a light film of grease. I think with copper or bronze there is no need to worry about corrosion. If it were me (I know, it ain't) I would just put it together.

[cywelchjr]

I looked at things and did't bother with the o-rings. I just put a good coating of RTV underneath the copper pipe, since the shaft I put the pipe on was a spare, I still have the original and I was able to put the pipe on and let the RTV cure before installation so I knew everything was secure first and since it was a metal to metal fit to start, I figured metal to metal now is fine. Everything is still going smoothly, and first Sat in June is a ride through the mountains, so I'll know how it handles it after that ride.

[Clyde K.]

Phil, I am doing my fd swap as we speak. Would a piece of 1/16 inch aluminum tub work since there isn't any weight bearing involved?