DIY "Universal" Seca Backrest

DIY Seca Backrest

One of the first accessories I wanted to install on my 81 Seca 550 was a padded backrest, both for form and function. Having recently re-covered the seat with a NOS factory seatcover ($20 eBay), I figured now was as good a time as any. If you do any 2 up riding, you will quickly discover the factory Yamaha “grab strap” just ain’t cuttin’ it (or so she says ). The problem was finding one to fit. So I diligently took measurements at all mounting points and widths, expecting to find my pick of used backrests on eBay. What I found was:
A)Most of the used backrests available on eBay are rusted, pitted, and or rotted, with their padded backrests in varying states of decay. And,
B)You can expect to pay somewhere between $50 and $100 delivered for a backrest that needs lots of elbow grease to look presentable, and may or may not fit without mild to severe modifications.
What I needed was a simple system to utilize a standard “Universal” type backrest. These seem to be the least in demand, and I picked up the nearly mint backrest shown in the photos for the grand sum of $1.00 and $15.00 S&H ($16.00 delivered). Another $6.00 in hardware from my local Tractor Supply, and I was all set, at a grand total of $22.00. Once all the parts have been gathered, the actual installation time is approximately 1 hour. A helper is handy for this project, but not necessary.
A few items worth pointing out are; the rear turn signals had to be relocated onto the bar itself. And also, you have to mount the backrest OVER the tail piece. This means that after re-connecting the turn signal wiring, you have to replace the tail piece BEFORE installing the backrest. Also, when taking your measurements, remember that the seat has to clear the backrest when lifted to gain access to the fusebox, etc.
Parts Needed:
1-Backrest
2-2.5” Long x 7/16” Hex Head Screws (unfortunately, they don’t seem to manufacture slotted round head screws in 7/16”).
2-7/16” Nuts for above screws
4-7/16” Flat washers for above screws
2-7/16” Lock Washers for above screws
2-1” Long x 8mm(?)* coarse Hex Head Screws
4-8mm(?)* Flat Washers For Above Screws
2-1.5” Long x 7/16” ID Spacers/Collars**
2-Approx. 5” Long Support Bars*** x 1/8” Thick Steel
*-Not sure if 8mm, but these are the same screws that bolt to the rear of the side grab bar. Although there is only 1 grab bar, there are mounts on both sides of the bike.
**-7/16” ID spacers or collars are difficult to find. I cut mine from some scrap tube stock.
***-Support bars were cut from 1/8” thick steel bar stock, drilled, rounded off and painted black. The holes are 8mm on 1 end, and 7/16” on the other, to accommodate the 2 different size screws used. The centers of the holes are the most critical measurements. Have someone hold the backrest upright, and so it just clears the seat when opened. Then measure from the center of the mouting hole on the backrest, to the center of the rear grab bar mount.
1)Lay out all the necessary parts, including the pre-cut spacers/collars, and the pre-drilled and painted support bars.
2) Lift the seat, and remove the tailpiece (4 screws-don’t lose the collars!).
3) Access the wiring just forward of the tail light, and disconnect the pair of leads for each rear turn signal. Note how they re-connect.
4) Remove both rear turn signals.
5) The diameter of the turn signal mounting studs is approximately 15/32. Drill out the top most mounting hole on each side of the backrest to this same diameter.
6) Mount the turn signals to these top holes, putting the (7/16” hole) support bars between the inside of the backrest and the nut. Just tighten enough so the bars and turn signals don’t move around. Re-connect the turn signal wires for each side, and prop up the backrest on the tail light.
7) Replace the tail piece on the bike, with the 4 screws.
8) Have someone center the backrest over the tail piece, in the position where the backrest will be mounted.
9) Mount the backrest to the bike by running a 7/16” screws through both bottom mounting holes (1 on each side) of the backrest. Put a flat washer on the outside of the backrest, then the 1.5” collars on the inside of the backrest, run the bolt through the original turn signal mounts on the bike, and finish with a flat washer, a lock washer, and a nut. Finger tighten.
10) Bolt the front of the support bars to the rear grab bar mounting holes, and tighten securely.
11) Securely tighten the turn signals, and the 7/16” mounting screws. If your measurements were correct, the backrest should be upright, and clear the seat when opened. This is why your measurements must be precise.
It’s a fairly simple DIY project that took approximately 1 hour to complete. The only tools needed were a set of wrenches and/or sockets. I apologize for my lack of step-by-step photos, but it’s 19 degrees INSIDE the garage, and I just wanted to get the backrest on the bike!

 

One more pic:

 

Nice, Looks pretty good in the pics! Way to go

 

Thanks Ace!

 

Very nice ...go into production!

 

PERFECT !!!! Thanks, is same as maxim . Pics are sure nice ! Figured somebody has worked it out. Great job