Lehman GL1500 Driveshaft info may help someone else somehow .....

[CrystalPistol]

I am not gonna repeat the thread I already posted in the Honda section, there are two posts there in which I have included a lot of information that might help someone else looking to cure a hiccup or replace a drive shaft. The subject of that thread was primarily addressing the spline fit from front U-joint yoke to shaft end (http://www.triketalk.com/forum/threa...it-easy-enough).

But it occurred to me that some never got a Lehman build manual with their conversion and some of these GL1500 / Lehman trikes are getting on in years. We love ours, we baby it .... it has it's own room, we've known it since it's birth in 1998 and knew the bike before that. We've loved the looks since she was first seen pulling out of his shop.

But if I hadn't already done some looking and digging .... if on a trip into 3-4 states away .... and the weak link of the whole drivetrain let go pulling out of a gas station two up with trailer as I gassed it .... let's say it could lead to some moments of panic.
I don't know how y'all feel, but as for me, I don't mind the weak link being an easy to replace part. In my reading all over the net, my querries of "Lee H Mann" here who has been doing Lehmans since the late '90s, and my conversations with the original owners who bought our's when it was just a "pupp of a GL1500SE bike" and which we saw later grow into a "full fledged Trike" after the owner went away to school, those who used it as a main ride while they built others for customers into 2004 when we bought it ....
.... consensus seems to be usually a drive shaft failure in these trikes results in damage to the drive shaft or just the Honda front U-joint itself.


Back in the early days, late 90s, early 00s .... Lehman instructions said to cut a stock GL1500 drive shaft to a length of 12.750" long when measured from tip of shaft at splined end to cut line. One also needed a Neapco #N2-28-357 Yoke bored centrally to 0.770" diameter (best done on a lathe). Then the shaft is inserted into the modified yoke so that exactly 11.125" of shaft remains ahead of said yoke. This should be a snug fit. Instructions show the dimension from center of rear U-joint holes to tip to be 13.50" which is not as easy to measure accurately without some thought.

Now is also the time to slip Honda joint on front and check for proper phasing according to instructions ... but I don't know that Honda machined all splines in all yokes to same orientation so I am not sure this step matters .... because next yoke likely will be off half a spline from perfect phasing. If they don't line up perfect, I err to the spline that sets the front drive U-joint a hair ahead of the rear U-joint. There are 21 splines, and odd number and each spline is 17 degrees of arc, you can't get more than half or 8.5 degrees off and if you turn it 180 degrees, you'll find that to be closer to 4 degrees max.

Now it's time to weld. Welding requires preheating the shaft and yoke as a unit to 500 degrees .... I attached instruction below for downloads. I see the instructions say to weld around shaft and to weld inside the yoke the stub. That shaft that served 60-70,000 miles or more from 1998 until last September 2015 is only welded at the shaft at front of yoke, there is no weld at the stub on mine (though I may someday remedy that someday). I guess the person CR had weld it was pretty sure of his weld .... and it is a pretty weld with no undercutting. It has never given indication of weakness even as she has spun a few inside tires when pulling out in a hurry in heavy traffic (and I assure you it was by accident). I have it as spare now that I carry in the trailer but it would be easy to order a Neapco yoke and take a good old drive shaft and make one if desired, fit it with a new joint at back and a good front joint ..... and have "just in case".

I can't help you with a new splined shaft / yoke combo ..... maybe LHM has spares?

Anyway ..... below are some attachments that may help someone else, and I'll take the liberty of quoting LHM's reply to my querries as they are pretty much the same as what my buddy has told me in the past as we talked with he and his wife over a fire pit or some good vittles at Rancho Viejo ....
.... which is partly why I just love riding my Lehman!

I have seen failures on both the un-splined and splined versions of the shaft. The welded (un-splined) versions might fail because of initial prep or a bad weld, but mostly from abuse. The original owners were mostly well trained in how they treated their trikes. The second owners were a little more brutal and the third owners are generally worse. The splined shaft failures are usually abuse. Of course proper phasing of the u-joints is imperative.

Failures of the driveshaft, even the front joint rarely cause significant damage such as transmission output shaft.

Driveshaft vibration can be caused by a lot of different things. The splined yoke being loose. It should have a set screw and a groove on the splines for the screw so that the yoke can't move on the shaft. Improper phasing of the u-joints and sometimes just simply rotating the front joint 180 degrees will reduce if not eliminate vibrations. The last thing is front yoke to output shaft. I have seen some that appeared to be good but putting the trike in gear the front yoke would move on the output shaft like the splines inside the yoke were bad. I have never seen an output shaft spline go bad. YET !!

And of course the last thing is balance which I have never seen when using the right parts.

[CrystalPistol]

Re: above post.

Shaft forward splines are great on both shafts, the lower one which is a welded unit just has a good supply of grease in splines.

Below is a pic of a Moog 430 or 1310BC ("Big Cap") Ford U joint as used at rear of my Lehman .... not two different cap outer diameters. There's 1-1/16 and 1-1/8" sizes. The larger two caps go into rear yoke where clamps are, made bigger with thicker walls to better resist distortion by ham fisted person snugging up bolts too tightly.



Also noticed that I neglected to say it looks like GL1500 and GL1800 front OEM U-joints share same crosses. That smallish looking cross doesn't appear to be a weak link so much.

[CrystalPistol]

I KNOW this thread is a couple or three years old …

But I was in the basement looking through stuff, and looking in a box of driveshafts, noticed that modified GL1800 u-joint pictured above in post #1 but of which I didn't elaborate. I suppose that in an emergency, it'd work in my trike … but it's longer on the transmission end yoke and shorter in the rear, though not by much. Overall, it's the same length, but where the GL1500 and Valk U-joints would put the center of the cross dead center between the swingarm pivots, the modded 1800 U-joint would place the center of the crops slightly rearwards of the swingarm pivots center. The result would be slight forward & afterward movement of the shaft splines in the rear yoke, slight … but still there. With the other two joints, there is no such movement.

I also found it interesting that the OD of the yokes at widest point is same as the other two, the cross is the same size too.

[CrystalPistol]

Just playing with this so bear with me. The below pic is a compilation of two "crops" from the exact same bigger photo so it shows an accurate comparison of the GL1500 OEM U-joint, the "superceding" Valkyrie U-joint, and a modified GL1800 U-joint intended for trike use. I know the front yoke splines of all 3 will fit nicely on the output shaft of the GL1500. The top two U-joints will also fit the GL1500 drive shaft. The modified GL1800 U-joint has had a splined machined rear "adaption" to fit the GL1500 drive shaft splines welded 360 degrees. All three U-joints are the same overall length at 7-1/4", but the 1800 unit has a longer front yoke (7/16" longer) and shorter rear yoke (7/16" shorter) meaning it will work ... but it will result in some slight bit of sliding of the shaft splines lengthwise inside the rear adaption splines as the rear suspension of the trike works bumps. The upper 1500 & Valk U-joints put the cross center between the swing arm pivot points, so no lengthwise sliding occurs there. From all I can tell, the 1800 U-joint enjoys no superior strength to the Valk U-joint, all three have same "cross" delivering power.

In short, the 1800 U-joint as modified will work. I just found it interesting, that's all.

[CrystalPistol]

Photobucket looks to be down, am deleting pics …. so here is pic that was in post #2 above.

Below is a pic of a Moog 430 or 1310BC ("Big Cap") Ford U joint as used at rear of my Lehman .... note two different cap outer diameters. There's 1-1/16 and 1-1/8" sizes. The larger two caps go into rear yoke where clamps are, made bigger with thicker walls to better resist distortion by ham fisted person snugging up bolts too tightly. .

[Marc H]

Photobucket no longer allows photo from their site to be posted to forums without buying a premium membership or something like that.I copied everything I had and stored it elsewhere when they started it.

[CrystalPistol]

Photobucket no longer allows photo from their site to be posted to forums without buying a premium membership or something like that. I copied everything I had and stored it elsewhere when they started it.

Cleaned mine out too.

[CrystalPistol]

my 5th paragraph:

… etc ... Now is also the time to slip Honda joint on front and check for proper phasing according to instructions ... but I don't know that Honda machined all splines in all yokes to same orientation so I am not sure this step matters .... because the next yoke likely will be off half a spline from perfect phasing. If they don't line up perfect, I err to the spline that sets the front drive U-joint a hair ahead of the rear U-joint. There are 22 splines, and each spline is 16.363 degrees of arc so you can't get more than half or about 8.2 degrees off.

… etc …

02-08-2020:

First, I was off by a spline. It's 22 splines. Correction is in red.

Second, was looking around in shop today and for some reason and I picked up a OEM GL1500 drive shaft and tried it in that one "odd to me" modified GL-1800 U-joint end, it was a no fit. This seemed odd as I have pics of the "splined at both ends" Lehman custom D-shaft that's on the trike in this yoke?

Curious, I did some measuring. The 1800 U-joint as modified will work ... BUT only with the "splined at both ends" Lehman custom D-shaft. (see post #4 above)

I measured it close as I found the modified GL1800 U-joint would not fit an OEM Honda GL1500 driveshaft. Trans end yoke is a OEM Honda GL1800 yoke so it will fit transmission out shaft, so it was not measured. I medasured what I measured in several places, counted splines repeatedly too. Drive shaft end yoke has 22 splines, 0.887" deepest (max ID), & 0.801" at tops of the splines (min ID) ... a Honda OEM Drive shaft's splines measured 0.818" deep or (min OD), & 0.891" at tops of splines (max OD). That 0.818"/0.891" shaft spline will not readily fit inside a splined 0.801"/0.887" hole and butter won't help. Right number (22) of splines (I had counted 21 before, so today I marked ... & counted on both the shaft & yoke several times, there's for sure 22 splines), but the modified 1800 U-Joint's hole is too small (to accept a Honda OEM D-shaft spline) … or the OEM Honda shaft is too big … by just a few thousandths of an inch.

It tells me the spline fit is likely a looser between the "splined at both ends" Lehman custom D-shaft's splines and the Honda Valkyrie U-joint's splines. As a result, I will likely put the Valkyrie U-joint (that's near new miles wise with "snugger upper" mod) back on the welded drive shaft that is made with Honda OEM D-shaft (it has over 60,xxx miles on it as is), get that puddle weld done at very end of driveshaft inside yoke at rear (done it 02-10-2020, I feel some better about it now but it never posed a problem, just me knowing it wasn't done), and I'll put that under the trike and carry the splined shaft, yoke, extra rear U-joint in the yoke, & a spare front U-joint that fits … to carry in the trailer as a spare when desired.

I know, "big deal" ... but you never know …