I rebuilt the front forks with Race Tech cartridge emulators and you can read about how I did that here:

• 31 BMW R100RS/RT Rebuild Forks With Race Tech Cartridge Emulators

Now I am upgrading the top fork brace with a Toaster Tan top brace and the Toaster Tan steering stem nut with the longer skirt. The BMW top plate is a thin piece of steel. IMHO it is not up to the task of keeping the forks aligned, particularly under hard braking and cornering.

The Toaster Tan steering stem cap nut has a longer skirt that is a tighter fit in the hole in the top brace than the BMW stock steering stem cap nut. This improves the rigidity of the top plate connection to the steering stem stiffing the front suspension.

Since the top brace is an integral part of the front fork assembly, you will want to read about how I install the front forks and align them here:

• 31 BMW 1983 R100RS/RT Install and Align Front Forks

Parts

Beside the Toaster Tan parts, I replaced the instrument cluster rubber grommets and the corroded metal caps that go on the ends of the large grommets. I also replace the handlebar riser studs with longer Allen bolts.

Part #	Description	Qty
TT-101	Top Brace, 36 mm forks-Toaster Tan (Black)	1
TT-301D	Top Brace Center Acorn Stem Nut with Damper Hole	1
31 42 1 235 620	RUBBER GROMMET, Intsr. Bracket, 25 mm	2
31 42 1 235 615	RUBBER GROMMET, Intsr. Bracket, 19 mm	2
31 42 1 232 243	CAP, 25 mm Rubber Grommet	4
M8 Allen Bolt	M8 x 65 mm	2
M8 Allen Bolt	M8 x 55 mm	2

Video

VIDEO: 1983 BMW R100RS Install Toaster Tan Fork Top Brace

Install Steering Limit Bolt In Steering Head

I install the steering limit bolt in the hole on the front of the steering stem. It prevents the handlebars from hitting the inside of the RS and RT fairings when turning the forks.

Test Fit Fork Toaster Tan Fork Top Brace

I install the fork tubes before I test fit the fork top brace as shown here.

• 31 BMW 1983 R100RS/RT Install and Align Front Forks
  • Install Fork Tubes In Lower Yoke

I test fit the Toaster Tan top brace to make sure it fits easily on the top of the fork tubes and the steering stem. I finger tighten the Toaster Tan steering stem nut to make sure the top brace steering stem hole is aligned with the steering stem. If it is, then the steering stem nut should easily pass through the hole in the top plate. It the steering stem nut won’t easily pass through the top plate hole, check for bent fork tubes or any other reason for a misalignment between the fork tubes and the steering stem.

Set Height of Fork Tube Cap Ring

The Toaster Tan top brace comes with two precision machined cap rings that fit on top of the fork tubes. Unlike the stock top plate, the fork tubes are recessed inside the top brace holes which improves fork rigidity.

The rings are secured by the Allen pinch bolts that face to the front. They seal the top of the forks to prevent fork oil from escaping. The fork cap nuts rest on the rings and the rings need to be 0.7 mm proud of the top of the top brace so the bolts don’t contact the top plate. To determine how proud the rings are above the top brace, I first torque the steering stem bolt to 40 Ft-lbs to seat the top plate.

NOTE:
The steering stem nut torque specification is 80-88 FT-Lbs. The 40 FT-Lbs is just to ensure the top fork brace is firmly seated before installing the rings.

I use the hook spanner to keep the roller bearing preload nut from turning as I torque the bolt.

NOTE:
If you are just adding the Toaster Tan fork top brace and you don’t plan on aligning the front forks after installing it, you need to prevent the forks from contacting the steering stop on the lower fork yoke as you tighten the steering stem nut, or you will twist the forks out of alignment. That said, I would recommend that you check the fork alignment after installing the fork top brace. This procedure shows how to torque the cap nuts and not twist the forks out of alignment and how to check the fork alignment. 

• 31 BMW 1983 R100RS/RT Install and Align Front Forks
  • Use A Handlebar To Provide An Anti-Torque Arm

My cap rings were recessed a bit so I adjusted the fork tube height in the lower fork yoke until the rings were proud by 0.7 mm. When I had the rings at the right height, I tighten the fork cap nuts to 15 FT-Lbs to set the cap rings on the top of the fork tube and then tighten the forward facing Allen bolts on the top brace to 18 Ft-lbs to lock the rings on top of the fork tubes.

Then I tighten the lower fork yoke pinch bolts to 25 Ft-Lbs to secure the fork tubes in the lower fork yoke so they won’t move. Finally I remove the fork cap nuts since I’m going to align the forks after I install the top brace and I install the fork cap nuts to the proper torque later in that procedure.

NOTE:
The specification for the lower fork yoke pinch bolts for this bike is 28 FT-Lbs. But I’m using stainless steel Allen bolts from the bolt kit I got from “The Bolt Guy”. This requires anti-seize on the threads to prevent galling in the aluminum threaded hole in the lower fork yoke. Anti-seize is a lubricant so I reduce the torque about 15% to protect against stripping the threads.

Check Fit Of Instrument Cluster Bracket & Adjust

The instrument cluster bracket is not precise made and may interfere with the lower side of the Toaster Tan top brace. Mine interfere, so I use my bench grinder to grind down the edge of the bracket until it fits into the underside of the fork top brace. I plan to repaint the bracket. If you aren’t painting your instrument bracket, put some automotive touch up paint on the exposed steel on the edge of the bracket so it won’t rust.

Remove Handlebar Riser Studs & Replace With Longer Allen Bolts

Since the Toaster Tan top brace is thicker than the stock thin plate, the handlebar riser studs are too short. I remove them using doubled 8 mm nuts (I had to use triple nuts on the long studs as they were very tight). There is a long and short stud and I replace them with M8 x 65 x 1.25 and M8 x 55 x 1.25 Allen bolts. These will screw into the threaded holes in the top riser clamp to secure the instrument cluster bracket and the handlebars to the Toaster Tan top brace.

NOTE:
I had to chase the threads before installing the Allen bolts. I suspect the soft aluminum deformed a bit when I removed the studs.

Attach Instrument Bracket and Handlebar Risers

I painted the instrument bracket and handlebar risers and then attach them to the Toaster Tan top fork brace as I assemble and align the front forks.

The instrument bracket has four grommets, two large and two smaller, that cushion shocks to the instruments from the front end. I install these along with the steel sleeves that fit in their holes.

Quite a bit of hardware is used to mount the instrument bracket and handlebar risers.

The small grommet has a bolt, special flat washer and locking nut to secure the back of the instrument bracket to the fork top brace. The bolt head is on top of the brace. I like to use an Allen bolt as I like the looks of it.

The long M8 x 65 Allen bolt secures the front of the handlebar riser to the top brace. I add a flat washer under the Allen bolt head along with the wave washer that is used with the nut that would have been used with the stock studs. I think the flat washer improves the ability of the wave washer to lock the head of the Allen bolt.

There are two cover plates that fit on either end of the large grommet, so the top one is between the top of the grommet and the bottom of the top brace.

The shorter M8 x 55 bolt secures the back end of the handlebar riser to the top plate. Like on the longer Allen bolt, I add a flat washer to the wave washer to help secure the bolt head to the bottom of the top plate.

It can be a pain to mount the instrument bracket and the handlebar risers with all the hardware and gravity acting against you. It’s pretty easy if you do it this way.

1. Secure the rear of the handlebar bracket using the rear Allen bolt, flat washer and lock nut.
2. Insert the top cover plate on top of the large grommet in the gap between the grommet and the top plate.
3. Insert the longer M8 x 65 Allen bolt, flat and wave washers through the large grommet to secure the front of the handlebar riser .
4. While holding the longer bolt, install the bottom half of the riser than then thread the bolt a few turns into the top half of the riser.
5. Insert the shorter M8 x 55 Allen bolt, flat washer and wave washer through the rear hole of the top brace into the rear of the bottom half of the riser and thread it a few turns into the rear hole of the top half of the riser.

Torque Steering Stem and Fork Cap Nuts

At this point, you would torque the steering stem cap nut to 80-88 FT-Lbs and the fork cap nuts to 35 FT-Lbs being sure you don’t let the lower fork yoke stops rest against the steering stem limit as shown here.

• 31 BMW 1983 R100RS/RT Install and Align Front Forks
  • Toaster Tan Top Brace Final Assembly

Here is what the Toaster Tan fork top brace, instrument bracket and handlebar risers look like after I complete the fork installation.

Revisions

2020-05-28  Updated info on handlebar riser Allen bolts.