Hi Kell and CknDnr
I'm getting interested in installing disks on my 51FL. Any “how-tos" and pics will be appreciated
Thanks
King
Convert to brake disks
Forum rules
Please do not start new topics here, but here: New Panhead and Flathead topics
Please do not start new topics here, but here: New Panhead and Flathead topics
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krazyloop
Re: New bike - major decisions
An EVO motor will not fit in a knuckle frame without very extensive modifications that will change lines of the frame. It is too tall and the rocker boxes are too wide to fit unlike making a shovel or pan motor fit in there.
I ran a knucke frame, pan lower, and shovel upper for years without a problem. The frame sits slightly lower than a stock pan rigid frame. If you "remodify" the knuck frame back to stock it still won't have the value of an uncut original. Run it and have a good time.
As for brakes, I used the stock rigid rear mechanical and a pan wide glide front end. I mixed stock HD parts on the front end to use a disk brake. It all stopped just fine.
To install a stock FLH single disk brake on a 1971 and earlier wide glide, change the left lower leg to a 1972 and later. Get the 10 inch disk and mounting bolts. There are two types of this disk: the original which is slightly dished in the bolt pattern area and needs no spacer, and the one that HD made an engineering change to which is flat. The flat one needs the spacer. The spacer is about 4 - 5 inches in diameter, maybe 1/16th inch thick, and moves the disk slightly away from the hub so the caliper lines up. Present day replacement brake pads available from the HD dealer have a spec sheet in the box that gives the correct part number of the spacer. The spacer costs $5.
Next get the 1973 and later disk hub or use the 1972 and earlier hub. For the 1972 and earlier hub, you need the large aluminum spacer that bolts to the hub, then the disk bolts to the spacer.
Use the stock 1972 and later front caliper and either the FLH / Supergilde handlebar mounted master cylinder/ brake control with lever. If you use this set up you can also wire a kill switch to it. It has two buttons, one for an electric start, and the other for a turn signal. I suppose you could use these for a horn, etc.
You will need the correct axle for the hub, and the small spacer for the caliper side if you use the 1973 and later. I believe the 1972 and 1973 axles are different and you can learn that from the parts book.
One modification I made was using a Superglide speedometer and cable with the axle mounted sending unit. To get that to work I had to machine a spacer that slipped over the axle on the right side but with an OD that was small enough to accomodate the ID on the sending unit. This spacer will be somewhat on the thin side but that means nothing since it only slightly increases the axle diamter in a small area. It is not needed to make the front end or brake work properly. The spinner tang on the sending unit fits nicely between the open ends of the wheel hub bearing lockring/clip provided you use the 1973 and later hub. Then I used a stock HD speedometer cable and it worked fine. Extended speedometer cables are available if you have an extended front end. With a 19 inch Superglide front rim and tire or a 16 inch FLH rim and tire the speedometer reads correctly. If you have a transmission mounted speedometer sending unit you can skip this step.
This way, with the exception of the speedometer spacer, you will have all stock HD parts, and nowhere near the expense of Performance Machine parts. If you want a bigger diameter disk you will have to go with Performance Machine or someone like maybe GMA.
I ran a knucke frame, pan lower, and shovel upper for years without a problem. The frame sits slightly lower than a stock pan rigid frame. If you "remodify" the knuck frame back to stock it still won't have the value of an uncut original. Run it and have a good time.
As for brakes, I used the stock rigid rear mechanical and a pan wide glide front end. I mixed stock HD parts on the front end to use a disk brake. It all stopped just fine.
To install a stock FLH single disk brake on a 1971 and earlier wide glide, change the left lower leg to a 1972 and later. Get the 10 inch disk and mounting bolts. There are two types of this disk: the original which is slightly dished in the bolt pattern area and needs no spacer, and the one that HD made an engineering change to which is flat. The flat one needs the spacer. The spacer is about 4 - 5 inches in diameter, maybe 1/16th inch thick, and moves the disk slightly away from the hub so the caliper lines up. Present day replacement brake pads available from the HD dealer have a spec sheet in the box that gives the correct part number of the spacer. The spacer costs $5.
Next get the 1973 and later disk hub or use the 1972 and earlier hub. For the 1972 and earlier hub, you need the large aluminum spacer that bolts to the hub, then the disk bolts to the spacer.
Use the stock 1972 and later front caliper and either the FLH / Supergilde handlebar mounted master cylinder/ brake control with lever. If you use this set up you can also wire a kill switch to it. It has two buttons, one for an electric start, and the other for a turn signal. I suppose you could use these for a horn, etc.
You will need the correct axle for the hub, and the small spacer for the caliper side if you use the 1973 and later. I believe the 1972 and 1973 axles are different and you can learn that from the parts book.
One modification I made was using a Superglide speedometer and cable with the axle mounted sending unit. To get that to work I had to machine a spacer that slipped over the axle on the right side but with an OD that was small enough to accomodate the ID on the sending unit. This spacer will be somewhat on the thin side but that means nothing since it only slightly increases the axle diamter in a small area. It is not needed to make the front end or brake work properly. The spinner tang on the sending unit fits nicely between the open ends of the wheel hub bearing lockring/clip provided you use the 1973 and later hub. Then I used a stock HD speedometer cable and it worked fine. Extended speedometer cables are available if you have an extended front end. With a 19 inch Superglide front rim and tire or a 16 inch FLH rim and tire the speedometer reads correctly. If you have a transmission mounted speedometer sending unit you can skip this step.
This way, with the exception of the speedometer spacer, you will have all stock HD parts, and nowhere near the expense of Performance Machine parts. If you want a bigger diameter disk you will have to go with Performance Machine or someone like maybe GMA.