Page created from XLForum posts and pics, era model parts catalogs, parts catalog supplements, pics / documentation from JW Boon.com or NOS Parts.nl. 1)
There are conflicting views on what grade bolts to use.
Some say it's best to use the original bolts which are grade 5 and that grade 8 bolts are seen as overkill.
The theory is that a grade 8 bolt is more brittle and doesn't have as much elasticity as a grade 5 bolt.
And that upon a collision, a grade 8 bolt would break or shear whereas a grade 5 bolt would bend or deform (but still remain “intact”).
(That reasoning is debatable however. Both have been used successfully)
Others say a grade 8 bolt is always harder, and stronger in tensile and shear than a grade 5. 2)
(30,000 psi higher in tensile strength and 40,000-50,000 psi higher in shear strength).
If loaded to failure, grade 5 will have more % elongation than a grade 8 before it finally breaks, but will still break at a lower stress than a grade 8.
If fasteners are elongating that much in any application, there are other problems.
Lower grades are used to save cost over higher grades when cost is a factor. Lower grades offer no mechanical advantage.
The MoCo's first use of grade 8 motor mount bolts was in 1986.
Rear Motor Mounts | ||||
Part# | Year model | Hole for kicker | Rear Mount Bushing | Notes |
16201-52 | 52-60 K Models/XL/XLH/XLCH | ✔ | ✘ | 4 hole mount. |
16201-58 | 61-E62 XLH/XLCH | ✔ | ✘ | 4 hole mount. Replaced by 16201-52 (-65) |
16201-58A | L62-66 XLH/XLCH 67-69 XLCH | ✔ | 16202-62 | 4 hole mount. |
16203-67 | 67-81 XL/XLH/XLS 70-81 XLCH | ✔ | 16202-62 | 2 hole mount. |
16203-82 | 82-83 All | ✘ | 16240-82 | 2 hole mount. Replaced by 16203-82A. Appearance- cast |
16203-82A | 84-90 All | ✘ | 16240-82 | 2 hole mount. Replacement for 16203-82. Appearance- billet |
Lower Front Mounts | ||
Sportster year model | Lower front mount (R) | Lower front mount (L) |
1957-1977 | 16210-52A (black) | 16213-52A (black) |
1978 | 16210-52B | 16213-52B |
1979 L1979 adition | 16210-52A (black) | 16213-52A (black) |
16210-77 (chrome) | 16213-77 (chrome) | |
Replaced by 16210-79 (black) and 16213-79 (black) | ||
1980-1981 | 16210-79 (black) | 16213-79 (black) |
16210-77 (chrome) | 16213-77 (chrome) | |
1982-E1984 | 16210-81 (black) | 16213-81 (black) |
L1984-1990 | 16210-84 (black) | 16212-84 (black) |
1957-1976 Top Mounts | |||
Year Model | Description | Part# | Notes |
1957-E1971 XL, XLH, XLC, XLCH | Head Straddle | 16250-57 | Original bracket. |
L1971-1976 | Head Straddle | 16250-57 | Relief machined on the motor side of the bracket. This version was sold for 1957-1976 models. |
1957-1964 XL, XLH 1959-1964 XLCH | Cross Brace | 69031-57 | Original XL, XLH bracket. |
1958 XLC, XLCH 1965-1976 XLH, XLCH | Cross Brace | 16251-58 | Has 2 holes for horn bracket on the end. |
1957-1976 | Straddle to Head Bolt (2) | 4618W | 7/16“ x 20 x 7/8” |
1957 XL | Straddle to Head Washer (2) | 6505W | 7/16“ x 1” x 1/8“ |
1958-1976 XL, XLH, XLC, XLCH | Straddle to Head Washer (2) | 6495 6495 HW | 29/64” x 15/16“ x 1/8” |
1957-1971 XL, XLH, XLC, XLCH | Straddle to Cross Brace Bolt | 4336W | 3/8“ x 24 x 1-1/8” Hex Head |
1972-1976 XLH, XLCH | Horn Bracket | 69129-72A | Has 3/8“ x 24 welded (straddle to cross brace) stud. |
1957-1976 XL, XLH, XLC, XLCH | Straddle to Cross Brace Nut | 7775 | 3/8” x 24 Flexlock |
1957-1971 XL, XLH, XLC, XLCH | Straddle to Cross Brace Washer (underneath straddle) | 6417 6417W | 3/8“ x 1-1/8” x 1/4“ |
1957-E1972 | Cross Brace to Frame Bolt | 16865-52 | 7/16” x 20 x 7/8“ (13/16” Hex Head) (w/ cotter pin hole, for XR) |
L1972-1976 | Cross Brace to Frame Bolt | 4726 | 7/16“ x 20 x 1-1/2”, (5/8“ Hex Head) |
1957-1976 | Cross Brace to Frame Washer | 6522B 6522HB | 29/64” x 1-1/8“ x 5/32” (.156“) |
1957-1976 | Cross Brace to Frame Washer | 6524 | 29/64” x 1-1/8“ x 1/64” (.016“) |
1957-1976 | Cross Brace to Frame Washer | 6521 6521W | 29/64” x 1-1/8“ x 3/32” (.094“) |
1957-1976 XL, XLH, XLC, XLCH | Cross Brace to Frame Nut | 7825 | 7/16” x 20 Flexlock |
The stud (or bolt) is threaded into an aluminum casting (the case) which is not noted for having great strength. 3)
So the wise move is to use a stud threaded into the case using red Loctite.
The reason is because this is the only time the case threads get disturbed again.
Keep in mind the question, “Just why did the factory do this”?
They did it because there is good engineering reason to use a stud over a bolt.
When you tighten a nut on the stud the nut takes all of the beating and stress as it compresses against the motor mount, not the aluminum case.
If you want to use a bolt, then you should have a Heli-Coil installed in the case first.
The old rear mounts and the crankcase have 4 holes. 4)
When Harley changed to 2 hole mounts, all they did was knock the front 2 holes off the old mount and later eliminated the 2 front holes in the case.
But the hole spacing stayed the same.
So if you want to use a 4 hole mount on a 2 hole case;
All you have to do, if you should be so lucky to find a steel mount, is saw off the front 2 hole area of the mount.
If you want to use a 2 hole mount on a 4 hole case, you'll have to stick some short bolts in to plug the 2 unused case holes but it should fit just fine. 5)
Here are the 4 kick only (4 bolt) rear motor mounts. 6)
From left to right (each pic below):
The first 3 use the 2-1/16“ long lower bolts (when not using the passenger peg mount).
The late one uses 2-1/4” long lower bolts (when not using the passenger peg mount).
The key to understanding the evolution of these is knowing that 60-down used a 6 bolt lower battery tray and 61-up used a 4 bolt battery tray.
In order to use the 6 bolt battery tray (up to -52b) the mount needs to be milled clear across the upper flange (iron mounts).
When the aluminum was introduced, the battery tray was modified to the 4 bolt -52c.
The two bolts at top flange were no longer incorporated into the tray, so the mounts were not milled.
More 16201-58 pics:
This mount could be had in 1960 for $25.70
11) 12)
1982-1990 mounts offset the engine 13/32“ to the left of the position for pre 1982 engines and don't have the hole in them for the kicker shaft to go through. 20)
1984-1990 Rear Mount:
This mount is made from billet aluminum and was also sold as a replacement for the 82-83 rear motor mount.
1957-1981 style lower front motor mounts. 27) |
1982-E1984 lower front motor mounts / filter mount. (left shown) 28) See this page in the Sportsterpedia for building your own filter / motor mount for previous year models. |
|
L1984-2003 style lower front motor mounts. 29) | |
Note:
There are no instructions or mention of how to attach these mounts in the FSMs other than basic statements to the effect of “install the bolts”.
Dr Dick's instructions in the sub documents in this section for details on how the washers for the straddle mount should reside UNDER the straddle mount.
And accordingly, the washers being on top under the bolt head is responsible (at least in part) for cracked heads at the threaded mounting holes for this mount.
Head to head straddle mount (or center mount or head steady):
There is only the one upper motor mount assembly from 57-76 consisting of a support brace between the heads and a cross mount from there to the frame.
Support brace (straddle mount) is engineered to deal with production tolerances, most owner created misalignments and is the first thing to assemble on top. 30) 31)
The straddle bracket (16250-57) mounts from head to head and a cross brace bolts to the straddle and ties back to the frame.
The straddle bracket changed in L1971 and again in 1979 but the part number stayed the same.
There were two different cross braces from 1957-1976. See the Parts List above for year models used.
There are three straddle mounts from 1957-1985;
Note:
There are no instructions or mention of how to attach these mounts in the FSMs other than basic statements to the effect of “install the bolts”.
Reference the sub documents in this section for details on assembly.
1977-1985 head strap (except 1979-E1981 XLS). 41) |
1977-1981 Top Rear Mount (16266-76) 44) | |
1982 XLS / E1983 XL Top Center Motor Mount 45) | |
L1983-1985 XL-XLX-XLS Top Center Motor Mount 46) | ||