TLR 8IGHT-XT, Manual

Roll Centers

Roll Center (RC)

Roll center is the point in space that a vehicle rolls at or around based on complete vehicle 

settings. Roll centers can be affected by a lot of different items. Typically, a lower roll 

center produces more traction and will cause the roll effect to produce more downward 

force. A higher roll center helps the rear end to square up better and helps reduce traction 

rolling on high traction surfaces. Balance of the front and rear roll centers is key for a well 

handling vehicle. Adjustments below noted with RC are all adjustments that affect roll 

centers.

Front Camber Link (RC)

The front camber link mounting points can be adjusted up and down on the inside and 

outside (with option parts) as well as moved in and out. 

Tower

•  Lower – increases camber gain (camber change through suspension travel), higher roll 

center, increases off-power steering, increases aggressiveness, decreases consistency, 

good on small, tight, or bumpy tracks.

•  Upper – decreases camber gain camber gain, lower roll center. 
•  Longer – decreases roll, increases high speed steering.
•  Shorter – increases roll, decreases stability.

Spindle

•  Lower – lower roll center.
•  Upper – higher roll center.

Rear Camber Links (RC)

The rear camber link mounting positions can be adjusted up and down on the inside and 

outside (with option parts) as well as moved in and out. 

Tower

•  Lower – increases camber gain, higher roll center, improves bump handling, increases 

traction corner entry, decreases traction rolling.

•  Upper – decreases camber gain, lower roller center, increases traction corner exit, 

decreases traction corner entry.

•  Longer – decreases roll, increases stability, increases traction.
•  Short – increases roll, increases steering, improves bump handling.

Hub

•  Longer – increases stability corner entry, increases steering corner exit.
•  Shorter – increases steering corner entry, increases traction corner exit.

A/B Block (RC)

By changing of the pills in both the A and B block together, the front roll center is raised 

and lowered. It also changes bone plunge and camber gains. When lowering the pills, also 

lower the inner front camber link one hole to match, vice-versa for raising the pills. 
•  Lower - lower roll center, increases front traction, increases steering.
•  Higher – higher roll center, decreases front traction, make the front not feel “into the 

track”.

Rear Hub Height (RC)

The rear hub can be raised (B) or lowered (A) relative to the suspension arm, moving the 

axle up or down. 
•  A – lower roll center, increases rear side traction.
•  B – higher roll center, increases forward traction.
When changing hub height, different inner camber link locations may be required. The 8X 

Aluminum Rear Hub Set (TLR334034) provides settings between A and B for fi ner tuning.

Front Spindle Height (RC)

By changing of the spindle shims, the spindle can be raised and lowered. This can change 

bone plunge, bump steer, and droop. 
•  High - lower roll center, increases front traction, increases steering, less traction rolling.
•  Low – higher roll center, decreases front traction, make the front not feel “into the 

track”.

Others

Front Kick-Up

Front Kick-Up is adjusted by changing the pills in the A and/or B blocks. Kick up is the 

angle of the inner front hinge pins relative to the fl at chassis plane. With 0/0 pills in the 

A/B blocks, the kick up is 12°.
•  More Kick-Up – increases weight transfer on/off the front end when braking/

accelerating, increases off-power steering and forward traction, improves absorption 

of bumps.

•  Less Kick Up – decreases weight transfer on/off the front end when braking/

accelerating, decreases off-power steering and forward traction, worsens absorption of 

bumps.

Caster

Caster is the angle kingpins are displaced from the vertical axis of the front wheels. Caster 

on this vehicle is the combination of the kick-up angle and the spindle carrier angle. 

Example

0/0 pills in the A & B blocks = 12°

17.5° Spindle Carrier = 17.5°

12° + 17.5° = 29.5° caster

•  More Caster - decreases initial steering, good on bumpy tracks.
•  Less Caster - increases steering, allows freer suspension movement.

Bump Steer

Bump Steer is the change in front toe throughout the front suspension travel. Bump steer 

is affected by caster changes also. Bump steer is adjusted by the washer height between 

the rod end and drag link and/or the rod end and the steering arm. More washer height 

(steering turnbuckle more parallel to suspension arm) has less bump out. Less washer 

height, more bump out.
•  More Bump Out – smoother steering, decreases steering corner exit, good for bumpy 

tracks.

•  Less Bump Out – more direct steering, increases steering corner exit.

Ackerman

Ackerman is the difference in steering angle between the inside tire and outside tire 

turning throughout the steering throw. Ackerman is adjusted by changing the mounting 

hole used on the drag link for the steering turnbuckle. 
•  Ackerman, least to most – Front, Middle, Rear holes on draglink
•  Less Ackerman – decreases initial steering, increases steering mid corner to corner exit.
•  More Ackerman - increases initial steering, decreases steering mid corner to corner exit.

Rear Toe:

Rear Toe In is adjusted by changing pills in the D block.
•  Less Toe In - increases wheelbase, decreases rear traction, increases top speed. 
•  More Toe In - increases forward traction corner exit, increases off-power steering, 

increases braking stability.

Rear Anti-Squat

Anti-squat is adjusted changing pills in the C block. Anti-squat is the angle of the inner 

rear hinge pins relative to the fl at chassis plane.
•  More Anti-Squat – decreases side-to-side roll on the rear, improves height off jumps, 

improves rear traction under acceleration.

•  Less Anti-Squat – decreases off-power steering and side-to-side roll on the rear, 

improves acceleration in small bumps, increases rear traction off-throttle.

Wheelbase:

Wheelbase is adjusted by moving the rear hub spacing within the rear arm. Hubs forward 

for a shorter wheelbase or hubs rearward for a longer wheelbase. 
•  Shorter Wheelbase – increases on-power rear traction, increases off-power steering, 

increases rear weight transfer, generally better on tight or slick tracks

•  Longer Wheelbase – increases on-power steering, decreases off-power steering, 

increases stability, improves bump handling

*Wheelbase characteristics can sometimes also be affected by the type rear driveshafts. 

When changing rear driveshaft types, test wheelbase settings again.

Track Width:

Track width is adjusted by changing the width of the wheel hexes, front and/or rear. 

Wider:

•  Front – slows steering response, decreases front traction, decreases traction rolling.
•  Rear – quickens steering response, increases front traction.

Narrower:

•  Front – increases traction corner exit, decreases high speed stability.
•  Rear – increases traction corner entry, increases high speed stability.

Sway Bars:

Sway bars help control the side to side sway (roll) of the chassis and distribute load from 

the inside wheel to the outside wheel. 

Front

•  Thinner - increases off-power traction, decreases on-power steering. 
•  Thicker - decreases off-power traction, smoother steering corner entry, increases on-

power steering. 

Rear

•  Thinner - increases traction, decreases on-power steering. 
•  Thicker - increases stability mid corner, increases on-power steering, increases stability 

on high speed, high traction tracks.

71

71