bullneck frame with inline forks

[Martin Pettingell]

Hi,

I'm in the process of restoring a 1947 UL. The bike has whats looks to be an original bull neck frame which is in good overall condition. There are, however, no forge markings that i can find on it.

The engine has a good early 47 number so i guess it might have been a late 46 construction.

It came with a set of genuine OEM 'in line' forks - they had been chromed at some stage but looked like they had been on the bike for a long time.

I appreciate that it should have had 'off set' forks for that year. How and when they were changed is lost in the mists of time

At some stage i may be able to swop them out with original 'off set' forks but for the meantime i plan on running with what i have.

Question is will the bike run / handle ok with that set up.

Does anybody out there have experience of running a bull neck frame with in line forks?

The bike came with an 18 inch wheel up front and a 16inch on the rear + a spare 16 inch wheel.

I'd like to run with two 16 inch wheels in the first instance and maybe get a second 18 inch in the future so i could run with either.

Thanks

Martin

[vph-d]

The bike should handle just fine. What you have is a 30 degree neck frame and a straight fork, which is the same as all big twins 48 thru 84.
VPH-D

[Martin Pettingell]

Thanks - thats just what i needed to know and reassuring.

Martin

[Rubone]

I don't agree with this. The original bullneck frames came with straight forks. This was shortly changed for offset forks which continued through the '48 model year and into '49 on some models. '49 through '57 Hydra-Glide forks were straight, but with the advent of the swingarm frame were once again offset. The axle on a H-G is inline with the fork legs, on a springer it is forward of the legs. Using a springer on a bullneck reduces ground clearance but also changes the relationship of rake and trail making for heavy slow speed steering and twitchy high speed. I had a '47 once with an inline fork running 16" wheels and it was very prone to high speed weave/wobble.
Lots of '46s were built with inline forks, but the factory didn't change it just for fun, they had reason to do so.
Robbie

[Sargehere]

The change from in-line to offset (actually "de-raked") forks was made in mid-season, 1946. If you have a low numbered '46 and in-line forks, they might be the what came on the bike originally.

You may avoid the propensity towards high-speed wobble by just sticking to 18-inch wheels. They were still available on new Harleys in 1946 The change to 16-inch wheels, 1940, coincided with the appearance of the wobble gremlin. But it's not radical. Like with any front end wobble, when it appears, the rider should let off the throttle (change speed) and push hard on both sides of the handlebars until it abates.

[knuckleheadtim]

Check your springer carefully to be sure it's actually an inline. It isn't uncommon for the stem to be tweaked on an offset so an inline top tree or handlebars can be fitted to it. On an offset springer, the stem is offset about an 1/8" back on top, and an 1/8" forward on the bottom. I've gotten into many arguments over this at meets, but it's easy enough to see with a straightedge placed across the tubes.

Reproduction offsets are not correct; they're inline on the bottom and offset on top.

[Martin Pettingell]

Thanks everybody - that interesting stuff.

The engine on this bike is 47 Ul 13** - might it have come with inline forks? At what point in the year did the factory start preparing their next years machines ie. when in '46 did the motors start to be stamped '47?

I'll check the forks again to make sure they are not off set / tweaked straight but i'm pretty sure that is not the case. If they have been tweaked in this way would that mean that at the business end the rake and trail would be as the factory intended?

Welcome any further thoughts


Martin

[Rubone]

The engine on this bike is 47 Ul 13** - might it have come with inline forks?

Absolutely not, no '47 production came with inline. As stated before the inline ended midway through the '46 model year, which means it likely ended before the end of 1945. The production changed in late summer to early fall, depending on year. Some years, like '47 it went longer due to demand and need to fill existing orders.

If they have been tweaked in this way would that mean that at the business end the rake and trail would be as the factory intended?

No

[Martin Pettingell]

OK - thanks again for the help

Martin

[Chris Haynes]

Absolutely not, no '47 production came with inline. No

Except Servi-cars and WL's which remained in-line.