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2812 Series mono-tube double adjustable dampers

The 2812 is a monotube damper, this means the damper only has one working tube. When the piston rod is pushed into the body of the damper, it displaces its own volume in oil. To make this possible a part of the damper is filled with nitrogen. This nitrogen can be compressed and is separated from the oil by a floating piston. When the piston rod is pushed into the body of the damper its volume will push down the floating piston a little bit and thereby creating more space in the cylinder to accept the intruding piston rod. With movement of the damper oil will flow through separate cartridges. In these cartridges the oil will flow through valve loaded ports. When the oil flows through it creates a pressure drop over the piston which gives a damping force on the piston rod. The use of separate cartridges for the 2812 is a unique and patended KONI feature. The damper forces are generated by the amount of oil flowing through the piston and not the much smaller amount of oil displaced by the piston rod only.
Working principle of the damper in bump.
The damping characteristic can be divided in two velocity ranges. The low speed range from 0 up to 0.2 m/s and the high speed range from 0.2 m/s and higher. The low speed damping is controlled by the valves in the bump cartridge. (see figure 2) So when the damper is compressed pressure will build up over the piston and the valves in the bump cartridge will open. (see left hand side of figure 2) The valves are thin steel plates which will bend due to the oil presssure. The bump cartridge can be exchanged easily if a different range of bump damping forces is needed. For the high speed damping a separate main valve is used. When at high damper speeds the pressure difference over the piston still increases the high-speed main valve is opened. (see right hand side of figure 2)


Working principle of the damper in rebound.
The damper characteristic can be divided in two velocity ranges. The low speed range from 0 up to 0.2 m/s and the high speed range from 0.2 m/s and higher. When the damper is extended, pressure over the piston increases and the valves in the rebound cartridge will open. (see left hand side of figure 3) The valves are thin steel plates which will bend due to the oil presssure. The rebound cartridge can be exchanged easily if a different range of rebound damping forces is needed. When the oil still can not flow away quickly enough the pressure difference over the piston will increase and the high-speed main valve is opened. (see right hand side of figure 3).		2812 fluid flow path


How to adjust bump:
Both bump and rebound adjuster require a pin with a diameter of 1.5 mm. The adjusters are marked with letters that are stamped on the alloy top.
  1. The bump adjuster is marked with a B (bump). To increase the bump force, put the adjuster pin next to the minus sign and turn the pin towards the plus sign.

  2. The adjuster has 7 distinct stops (clicks), each of which marks an adjustment position. There are a total of 8 adjustment positions.

  3. The bump adjuster has a positive stop on the minimum and maximum position. Do not force the adjuster as damage may result!

How to adjust rebound:
  1. The rebound adjuster is marked with an R (rebound). To increase the rebound force, put the adjuster pin next to the minus sign and turn the pin towards the plus sign.

  2. The adjuster has 7 distinct stops (clicks), each of which marks an adjustment position. There are a total of 8 adjustment positions.
  3. The rebound adjuster has a positive stop on the minimum and maximum position. Do not force the adjuster as damage may result!

2812 Specifications



The 2812 is a modular damper. This means that all the dampers within the 2812 range share the same basic dimensions and features. The damper lengths and damping characteristics (or valvings) can be chosen to your individual needs. Please see the valving page for details. The 2812 MKII comes standard with 7/16" bearings at both ends. The rod end can be made as need on this damper. However, the 2812LB can be made with 1/2" or specialized attachments as needed.

The generic part number of the 2812 damper is:
2812 Part Number System
2812 Dimensions    
2812 eye drawing 2812 eye drawing
2812 eye drawing 2812 eye drawing
2812 eye drawing
Figure 4: General dimensions of 2812 MKII damper and available top fittings (see table 1).
Top eye and spring seat coding system.
2" spring seats
 Adjustment
window
2 1/4" spring seats
 Adjustment
window
A = std. Top, #1 ID bearing 7/16”
0º
 G = std. Top #1 ID bearing 7/16”
0º
B = +5 mm, #2 ID bearing 7/16”
0º
 H = +5 mm, #2 ID bearing 7/16”
0º
C = +10 mm, #3 ID bearing 7/16”
0º
 I = +10 mm, #3 ID bearing 7/16”
0º
V = +10 mm, #3 ID bearing 7/16”
90º
 S = +10 mm, #3 ID bearing 7/16”
90º
W = +10 mm, #3 ID bearing 1/2”
0º
 O = +10 mm, #3 ID bearing 1/2”
0º
Y = +10 mm, #3 ID bearing 1/2”
90º
 Z = +10 mm, #3 ID bearing 1/2”
90º
P = no top eye, no upper spring seat T = no top eye, no upper spring seat
R = no top eye U = no top eye
N = no top eye, no spring seats
Table 1: top eye and spring seat combinations The following damper lengths are available.
Type
Code		 Lmax
[mm]		 Lmin
[mm]		 Stroke
[mm]		 Lbody
[mm]		 Type
Code		 Lmax
[mm]		 Lmin
[mm] 		Stroke
[mm]		 Lbody
[mm]
214 214 185 29 139 403 403 242 114 233.5
219 219 190 29 144 433 433 262 124 253.5
224 224 190 34 144 473 473 282 144 273.5
229 229 195 34 149 513 513 302 164 293.5
234 234 195 39 149 553 553 322 184 313.5
239 239 200 39 154 593 593 342 204 333.5
244 244 200 44 154 633 633 362 224 353.5
249 249 205 44 159




254 254 205 49 159




259 259 210 49 164




264 264 210 54 164




269 269 215 54 169




274 274 215 59 169




279 279 220 59 174




284 284 220 64 174




289 289 225 64 179




294 294 225 69 179




299 299 230 69 184




304 304 230 74 184




309 309 235 74 189




314 314 235 79 189




319 319 240 79 194




324 324 240 84 194




329 329 245 84 199




334 334 245 89 199




339 339 250 89 204




344 344 250 94 204




349 349 255 94 209




354 354 255 99 209




359 359 260 99 214




364 364 260 104 214




369 369 265 104 219




374 374 265 109 219




379 379 270 109 224




384 384 270 114 224





Table 2: length table
Note: the black area contains the special Long Body dampers.
* Tip: always choose the longest Lmin you can accommodate. This ensures the lowest friction plus the best durability. «Back
2812 MKII

KONI North America - Racing Division
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