Wheels/Brakes

Front Brake

Stopping is a good thing so we wanted to put a hydraulic disc brake up front. We used the disc from the Yamaha wheel and matched it to a Sportster caliper. Mounting the caliper onto the springer fork turned out to be one of the most difficult issues we had to deal with respect to fabricating parts.

Since the disc/wheel moves up and down similar to but not exactly with the front leg of the springer, we anchored the bottom of the caliper to the front axle so it would travel the same as the disc. Then we fabricated a pivot arm which connects to the top of the caliper to the front (moving) fork leg. This way, the caliper is held at the same location on the disc regardless of the motion of the front wheel.

Well, getting the wheel centered, caliper aligned, spacers proper thickness, and pivoting properly was a lot more work than we had first planned... Looks pretty damn good though!

We used a Sportster handlebar master cylinder and 40" brake line to connect with the matching Sportster calipers that Kade took off of one of his other projects.

Front Wheel

We used a front wheel from a 1973-75 Yamaha RD 350. The wide rotor gave us plenty of room to work with since we're using a disc brake on a springer fork. With a springer, the disc will move up and down a bit under breaking. We wanted to make sure the disc was wide enough so the calipers maintained a bite even though the disc was moving around.

Front Axle & Bearings

The front axle is from a Big Twin springer fork, original diameter is .6825". Wheel bearing part # 28-6303. Bearing outside diameter 1.8500" center (.6865), width .5500". We turned the axle down to 17mm to fit the Yamaha bearings and replace the stock bearings with a little higher quality sealed bearings, FAG 6303.2RSR.C3.

Rear Wheel

The rear wheel is a 16" WLA five star reproduction as is the brake assembly from 45 Restorations. The WLA front and rear hubs are interchangeable, but we opted for a larger wheel and disc brake up front to get us stopped a little better and well... hell, it just looks good!

Put a brand new pair of reproduction brake shoes in from 45 Restorations as well.

Rear Brake

We used a cable for the brake, which had to be routed to the left side rather than on the right like the original. We used a chrome WLA reproduction clutch lever for the foot shifter to keep the look, but modify the function somewhat. Can't remember where we picked up the brake light switch, but it seems made to fit.

This table converts metric, alpha and inch size tires.
Front Tires			Rear Tires
metric	alpha	inch	metric	alpha	inch
80/90	MH90	2.50/2.75	110/90	MP85	4.00/4.25
90/90	MJ90	2.75/3.00	120/90	MR90	4.50/4.75
100/90	MM90	3.25/3.50	130/80		5.00/5.10
120/80		4.25/4.50	140/80		5.50/6.00
120/90	MR90	4.25/4.50	140/90	MU90	5.50/6.00
130/90	MT90	5.00/5.10	150/80	MV85	6.00/6.25
			150/90	MV85	6.00/6.25

Speed Rating Chart
Motorcycle Speed Ratings	Maximum Design/Test Speed
	J Type	62	100
	N Type	87	140
	P Type	94	150
	S Type	112	180
	H Type	130	210
	V Type	149	240
	Z Type	149+	240+
	Tires with 2.00, 2.25 & 2.50 nominal section widths are rated for 75 mph.

LOAD INDEX RATING CHART
LI	lbs.	LI	lbs.	LI	lbs.	LI	lbs.	LI	lbs.
20	176	33	254	46	375	59	536	72	783
21	182	34	260	47	386	60	551	73	805
22	187	35	267	48	397	61	567	74	827
23	193	36	276	49	408	62	584	75	853
24	198	37	282	50	419	63	600	76	882
25	204	38	291	51	430	64	617	77	908
26	209	39	300	52	441	65	639	78	937
27	215	40	309	53	454	66	661	79	963
28	220	41	320	54	467	67	677	80	992
29	227	42	331	55	481	68	694	81	1019
30	234	43	342	56	494	69	716	82	1047
31	240	44	353	57	507	70	736	83	1074
32	247	45	364	58	520	71	761	84	1102

Load Rating - A numerical code which corresponds to the total load carrying capacity at the speed indicated by the speed symbol.

STREET TIRE SIZE DESIGNATION

METRIC DESIGNATION

INCH DESIGNATION

ALPHABETICAL DESIGNATION

Rollin, Rollin, Rollin...

Front Brake

Front Wheel

Front Tire

Front Axle & Bearings

Rear Wheel

Rear Brake

Rear Tire

Motorcycle Tire Size Conversion Chart