Front End Upgrades


As stated before, the Seca's front suspension and brakes leave much to be desired.

This page will hopefully help a few decide if they wish to do any of the more common modifications to their ride themselves. 



Tip: (Taking some digital photos during the disassembly process can be of great help during reassembly! Any project is hopefully going to be quick, but when things get in the way to delay you, having a visual refresher sure help keep the confidence level up!)

What are the common upgrades?


Steering Head Bearings

Fork springs

Braided brake lines

Brake pads





Steering Head Bearings



First, the steering head bearing are getting old and sloppy.  Rather than replace them with OEM units, it is recommended you install tapered needle bearing instead.  These style bearings distribute the load across a larger race, as well as provide far better support for lateral loads.

You can see in this image the new bearings installed, with the old lying in the foreground.



Fork Springs


At first I though someone had already upgraded the springs on my '83, as I discovered that they were already Progressive wound.

(After reading about so may so many write-ups on the poor front end, and progressive suspension upgrades, I had assumed they were not.)

A quick review showed me that Yamaha did in fact use them.

A company by the name of Progressive Suspensions make a slightly thicker set to firm up the feel. (note the aftermarket springs are also longer that stock, leaving you to cut down the spacer.



Getting the fork tube off is fairly simple, but I had trouble separating the inner tube from the outer tube thanks to the valve tube bolted inside. It was difficult to see how to remove it, and the manual references a special tool.

Here is what the top of that valve looks like, and the nut/bolt set I used to solve the problem (19mm Head).




Refilling with oil is a guess at best, as you cannot use the amount recommended in the service manual, or you will blow the seals on the bike.  I think I used about 15% less, and stayed with a 10 weight.



Braided brake lines


    The lines on the Seca are old and a possible failure point should they be dry and cracked.  Another problem is that OEM rubber line will balloon when put under extreme pressure (Such as grabbing a handful of binders in an emergency situation!)  This ballooning provides a mushy and vague feel to the front brakes at all times, and has been a constant source of complaints.

Fortunately, there are still aftermarket options to firm up that feel, and provide more power directly to the pads. 

Braided brake lines (Typically Stainless Steel, but I see Kevlar is now popular as well) will transmit all your lever force to the calipers, for a solid and predictable feel.

    Russell Performance and Spiegler offer upgrade kits, although any attempt to order a Russell kit from my local dealer was met with problems (the web site shows a part number, but the dealership books do not!)   A quick email to Russell directly had a set made up and on its way in about two weeks. (Part Number R09721        $107 +S/H at this time.) The set I got was clear coated as well.

    Installing the lower lines was simple and straightforward.  The upper line had problems I can only attribute to a manufacturing flaw.  When routed along the same path as OEM, the banjo fitting would not match up flush with the attachment points.  The "Twist" on the line was about 5% off and one soon discovers that BRAIDED LINES DO NOT TWIST!.


OK, so I should have stopped there, and sent the top one back for replacement, but with effort, I got things hooked up.



Refilling with DOT4 and bleeding the system was also frustrating (I may have to do it again, as I think there is still a bubble in the system) as there is little pressure to help gravity feed into and past the master cylinder.  A pressure bleeding system would have made things quick and easy, but stubbornness can eventually prevail!


WARNING:  Avoid letting brake fluid com in contact with your paint or tires!



Top of page


Brake pads


(coming soon)

Updated 1 Jun 2003