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Starting Member
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Last Login: 11/1/2008 8:46:30 AM
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| After wrestling my 1974 BMW R75/6/Velorex outfit around for almost three years, I have finally decided to install a leading link front fork setup. There doesn't seem to be much choice of products for my rig other than the UNIT leading links (out of England, I believe.) This is priced around $2,100.00 thru Side Striders, Inc. Does anyone out there have any experience with these forks? Are they really worth $2,100.00? Is there other manufacturers providing a less expensive product? Any input or shared experiences with leading link front fork setups would be greatly appreciated. Dedsled
DEDSLED "Just because you're paranoid, doesn't mean they're not all out to get you."
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Junior Member
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Last Login: 11/16/2008 7:11:51 AM
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[quote]dedsled (5/27/2007)
After wrestling my 1974 BMW R75/6/Velorex outfit around for almost three years, I have finally decided to install a leading link front fork setup. There doesn't seem to be much choice of products for my rig other than the UNIT leading links (out of England, I believe.) This is pricedaround $2,100.00 thru Side Striders, Inc. Does anyone out there have any experience with these forks? Are they really worth $2,100.00? Is there other manufacturers providing a less expensive product? Any input or shared experiences with leading link front fork setups would be greatly appreciated.
Dedsled
[/quote]
With the current exchange rate $2100 for the Unit Sidecar LL seems cheap. IIRC they're just shy of $1300 pounds - that's more like $2600 at todays exchange rate. I have Unit Sidecar LL on my GL1200 Goldwing. They do make steering easier but they won't eliminate wobble.
The Unit Sidecar LL are also more adjustable than the standard slider front end, the stiction you get with slider forks if nearly eliminated.
Have you checked if the LL from earlier BMWs will fit your '74? That might be a less expensive option. If you yahoo you could join one or more of the sidecar groups. I'd start with this group http://autos.groups.yahoo.com/group/SCT/ and go from there.
Interesting signature.
John
Isaac Newton is my co-pilot.
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Average Member
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Last Login: 11/14/2008 10:08:58 AM
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The pre-1970 BMW's with Earles (LL) forks were superior for a sidecar. But it was more than just the front end, the newer rear swing arm was much better for solo riding but most BMW sidecar enthusiasts think the old frame combined with the Earles forks were better for sidehacking.
I have seen a number of "conversion" bikes where the old frame and leading link suspension is retained but a newer airhead engine and twelve volt electrical system is installed. The old pre-1970 engines did not have an oil pump but relied on "slingers" to distribute the oil inside the engine.
With a conversion, as long as you retain the four speed transmission, you have the option of changing the gearing for either solo or sidecar use. If I'm not mistaken, once you get a /6 or above transmission this is not a viable option.
If you have never experienced a LL front end there are some differences than the telescoping front end. First, there is no front end "dive" when you are braking. Some riders like this because they feel it is a much steadier ride. However, most riders agree that the LL suspension is not as comfortable as telescoping shocks. Riding solo, the LL front end is not as agile but if you are a conservative rider or pulling a sidecar you may find it preferable.
Try ebay to see if there are any LL front ends available. You may be able to get one for much less.
Now, let me get this right - is it one down, four up?
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| dedsled what part of the "wrestling" is no longer tolerable? have you actually driven a hack with LL forks? what makes your telescopic forks unacceptable? your telescopics may only need a decent brace and steering damper? did you make a spring rate change? i take it that you have experimented with alignment? if your hack is adjustable to move the outboard wheel fore or aft by a couple of inches, have you played with that setting? i would be looking for a salvaged earles if it was me.
nobody rides half as well as they know how.
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Thanks for your responses, everyone. It's nice to see there are still a few "hackers" out there watching this forum. I have tried adjusting the chair fore and aft as well as the lean angle in relation to the bike. The tug has always had a fork brace and a steering dampener (from an old Volkswagon, if I'm not mistaken.) The "wrestling" is tolerable around town but on longer trips (I just completed a journey up the PCH and 101 from L.A. to Portland, OR. and back) it takes a few days to get the feeling back in my hands and shoulders. Also, my wife has expressed a desire to learn to drive the rig and she has had two carpel tunnel surgeries, making it difficult for her to fight the constant pulling to the right inherent with a side car outfit. I have been told by several experienced drivers that the leading link setup will improve that situation a great deal. I have pretty much decided to bite the bullet and go for the UNIT unit. (Pardon my redundancy.) Thanks again to everyone.
DEDSLED"Just because you're paranoid, doesn't mean they're not all out to get you."
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Here's my $0.02 for all it's worth...
I'm not exactly a seasoned hacker but I've got some experience with a LL fork. However, I've got no experience with a sidecar and telescopic fork.
I have a '76 R75/6 with a ural sidecar installed. I replaced the telescopic forks with a set of Unit LL forks before giving the telescopic ones any shot at a test run.
The Unit forks will come with a bushing (more than likely) that goes in the lower triple clamp to fill the void between their inner diameter and the forks outer diameter. I had to turn the bushings down a little bit to get them to fit and it still took a lot of effort to get the forks seated to the upper triple clamp. So much so that I don't think I could fit the originals back on without a new lower clamp. That is to say I don't think I will be able to remove the LL forks from the lower triple clamp.
They allow you to raise and lower the front end which will allow you to adjust, to some extent, the rake and trail. I found that I had to settle for the adjustment that mimized the head shake or wobble that seems inherent in a sidecar rig. I have had some folks tell me the wobble is never going to go away and others say if properly set up the wobble can be abolished without a damper. Zero trail should in theory ease the steering effort, but you still need to fight the physics involved in having mass off to one side. Best done with braking and throttle to aid steering input. I have been pleasantly surprised by just how a little amount of engine braking or acceleration facilitates a turn.
My OEM BMW damper was shot (30 years must offer some wear and tear on the unit!) and it afforded no relief. I replaced it with a new one and at first it just about fixed the wobble. After a few miles it appeared to lose some of its damping quality and I now have a very mild (and tolerable) wobble at low speeds. A little front brake application, throttle, or a deliberate swerve seem to stop the wobble. I'd definitely hang on to the steering damper on your current set up.
You mention the bike pulls to the right still. Supposedly if properly set up it should track straight under neutral throttle/braking conditions and only pull to the right under acceleration or to the left on braking as expected with a rig. What I have found is that mine will track straight at a given speed but pull to the right some as I exceed that speed.
This is only a slight pull but present none the less. I haven't attempted to alter things to see if I can get it to track straight at higher speeds yet. I assume this will be possible with some minor adjustments to toe in or lean out or both. It seems to be an ongoing experiment.
The antidive effect of the LL forks is nice. And I get no end of comments on the bike's appearance, including the Unit forks.
I can tell you from recent experience that doing 200+ miles in strong head winds on a rig is a serious workout.
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Starting Member
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| Well, the deed is done. The installation of my new LL front forks is complete and I have driven the rig about 150 miles with this setup. All the mileage has been in town so far and I don't think I can put into words the difference the LL forks make with the way my rig handles. At first I thought I had made a mistake going this route since the "feel" of the rig was so different. Sort of like driving a car with power steering for the first time. At first, I was worried that I might inadvertently "fly the chair" in right hand turns because the rig steers so effortlessly and I was used to having to pull the handlebars with gusto to get the outfit to go around a corner. But now, with a little practice, I have grown used to the light touch it takes to change directions. There is still a little wobble felt as the sidecar tire goes over bumps but it is much less noticeable than before. The rig seems to track straighter over rough pavement and just seems more settled over all than with the stock forks. The best news is that my wife now has sufficient strength to easily control the rig and has been practicing her driving every day before work. To see the smile on her face as she drives around the neighborhood with the dog in the hack and the neighbors out cheering her on is worth the price of admission. So the final verdict, at least for me, on installing leading link forks is: I should have done this years ago. Dedsled
DEDSLED "Just because you're paranoid, doesn't mean they're not all out to get you."
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