Short answer: Unity Manufacturing spotlight screws are torqued in inch-pounds, per your installation sheet. On Unity's universal sheet 420-A, the bracket screw takes 50 ± 5 in-lb if the outer-tube bushing has a flat, dimple or groove, or 60–70 in-lb if it has none. The handle's wedge screw takes 60–70 in-lb with a curved wedge, 25–35 in-lb with a flat one.
Last updated: October 2026 · By SpotlightDepot Team, an authorized Unity Manufacturing dealer · Compiled from Unity instruction sheets 420-A Rev. C (2007), 4392 Rev. G (2002), 3751 Rev. C (2002) and 8546 Rev. A (2011), plus the Unity handle parts sheet for U-6701-0101 (2014).
The wedge screw is the value that varies most, from 25 to 70 in-lb, because it depends on the wedge type and the sheet. If a wedge or its screw is worn or mismatched, a replacement set costs far less than a handle: the wedge bushing and screw for flat shafts, the wedge bushing and screw for round shafts, or a complete Unity U-6701-0101 replacement handle, which comes with wedges and screws for both shaft types.
What torque does each Unity spotlight screw take?
Every torque value in Unity's four spotlight installation sheets is in the table below, grouped by where the screw sits. Use the row for the sheet that came with your kit; the sheets do not all agree.
| Screw | What it does | Torque (in-lb) | N·m | Unity sheet, step |
|---|---|---|---|---|
| Bracket | ||||
| Bracket set screw or clamping screw (outer-tube bushing has a flat, dimple or groove) | Seats the outer tube in the bracket and sets its notch orientation | 50 ± 5 | 5.1–6.2 | 420-A, step 14A |
| Bracket clamping screw or set screw (bushing has no flat, dimple or groove), tightened after the notch is set | Locks the outer tube once the notch orientation is set | 60–70 | 6.8–7.9 | 420-A, step 14H |
| Bracket set screw J, Ford Crown Victoria | Holds the exterior tube in the bracket | 45–55 | 5.1–6.2 | 3751, step 4D |
| Bracket set screw, Ford Explorer | Engages the dimple on the outer-tube bushing | 50 ± 5 | 5.1–6.2 | 8546, step 9b |
| Handle (wedge screw) | ||||
| Wedge screw, curved wedge (round shaft, no flat) | Locks the handle onto the shaft | 60–70 | 6.8–7.9 | 420-A, step 18 |
| Wedge screw, flat wedge | Locks the handle onto the shaft | 25–35 | 2.8–4.0 | 420-A, step 18 |
| Wedge screw Q, inside "A" pillar installation (flat wedge) | Locks the handle onto the shaft | 65 ± 5 | 6.8–7.9 | 4392, step 6c |
| Wedge screw L, Ford Crown Victoria (flat wedge) | Locks the handle onto the shaft | 65 ± 5 | 6.8–7.9 | 3751, step 7C |
| Wedge screw, Ford Explorer (flat wedge) | Locks the handle onto the shaft | 40 ± 5 | 4.0–5.1 | 8546, step 11b |
| No torque value given | ||||
| Head-housing set screws (up-down and rotation) | Set the tension that holds the head's aim | Just enough to hold aim in the wind | 420-A step 19; 4392 step 9; 3751 step 8; 8546 step 12 | |
| Bracket set screw K or clamping screw E, inside "A" pillar installation | Holds the outer tube in the bracket | No value on this sheet | 4392 step 5c | |
| Bracket mounting screws (self-tapping) | Hold the bracket to the pillar | Secure; recheck while drilling | 420-A steps 7 and 10; 4392 step 2f | |
| Collar set screw | Holds the collar against the inside trim | Tight against the trim | 420-A step 17; 8546 step 10c | |
N·m converted at 1 in-lb = 0.113 N·m and rounded to one decimal. Sheet revisions: 420-A Rev. C (2007), 4392 Rev. G (2002), 3751 Rev. C (2002), 8546 Rev. A (2011).
Why do Unity's sheets give different wedge-screw values?
For a flat wedge, the two 2002 sheets (4392 and 3751) call for 65 ± 5 in-lb, sheet 420-A Rev. C from 2007 calls for 25–35 in-lb, and the 2011 Ford Explorer sheet (8546) calls for 40 ± 5 in-lb. Our listing for the current flat-shaft wedge set also gives 40 ± 5 in-lb. The sheets were written for different installations and revised in different years, and Unity does not explain the difference. Treat the sheet packed with your kit as the authority. If you no longer have it, ask us with your kit or vehicle and we'll check the sheet for you before you tighten anything.
Flat or curved wedge: which one does your handle use?
Look at the end of the spotlight shaft. If the intermediate tube has a milled flat, the handle uses a flat wedge; the flat on the wedge meets the flat on the tube, which also sets the head's parking position. If the tube is round with no flat, the handle uses a curved wedge. Each wedge bushing has its own screw, and Unity's handle parts sheet says each screw fits only its own bushing, so don't mix them.
| Wedge | Shaft | Unity bushing | Matching screw | Torque on sheet 420-A |
|---|---|---|---|---|
| Flat | Intermediate tube has a flat | U-8918-P3 (replaces U-8384-P) | U-8385 | 25–35 in-lb |
| Curved | Round tube, no flat | U-1834 | U-1836 | 60–70 in-lb |
The complete U-6701-0101 handle includes wedge bushings and screws for both flat and round shafts.
Are Unity torque specs in inch-pounds or foot-pounds?
Every Unity value is in inch-pounds (in-lb). One foot-pound equals 12 inch-pounds, so 60 in-lb is only 5 ft-lb. A wrench set to "60" in foot-pounds would apply 720 in-lb, twelve times the spec. Use an inch-pound torque wrench or a torque screwdriver.
| in-lb | N·m | ft-lb |
|---|---|---|
| 25 | 2.8 | 2.1 |
| 35 | 4.0 | 2.9 |
| 40 | 4.5 | 3.3 |
| 45 | 5.1 | 3.8 |
| 50 | 5.6 | 4.2 |
| 55 | 6.2 | 4.6 |
| 60 | 6.8 | 5.0 |
| 65 | 7.3 | 5.4 |
| 70 | 7.9 | 5.8 |
Which tools does each screw need?
| Screw | Tool | Unity sheet |
|---|---|---|
| Wedge screw (handle) | 3/8" socket or box wrench | 3751, step 4A; 420-A tools list |
| Head-housing set screw R (up-down tension) | 1/8" Allen (hex) wrench | 3751, step 4B |
| Bracket set screw J | 5/32" Allen (hex) wrench | 3751, steps 3A and 4D |
| Any torqued screw | Torque wrench reading in inch-pounds | 420-A tools list |
The Allen wrench sizes come from the Crown Victoria sheet (3751); sheet 420-A lists Allen wrenches without sizes. Check the fit before you turn a set screw on another installation.
Which screws have no torque spec, and how tight should they be?
The two set screws on the head housing have no torque value on any Unity sheet. One sets the tension for the up-and-down swing, the other for 360° rotation. Tighten each just enough that the head holds its aim in the wind. The letters printed for them change between sheets: A and B on 420-A, the same letters swapped on the Ford Explorer sheet 8546, T and S on 4392, and R and P on 3751. Identify each screw by what it does. On the classical head housing, a clamping screw sets the up-and-down tension and Set Screw C the 360° rotation tension (420-A step 25).
The self-tapping bracket mounting screws and the collar set screw also have no torque value: fasten them securely, and recheck the mounting screws from time to time while you drill the shaft hole.
How to set them so the head holds its aim: Unity Spotlight Won't Hold Its Aim?
What happens if a spotlight screw is too tight or too loose?
- Head-housing set screws too tight: the light is hard to aim and the parts wear early (420-A step 19; 4392 step 9; 3751 step 8).
- Up-down set screw too tight: the head is hard to swing up and down (3751 step 6C).
- Bracket screw too tight while setting the notch: the outer tube is hard to rotate into position. Snug it only enough to hold the tube until the notch is set (420-A step 14E).
- Wedge screw tightened without pressure on the handle: the switch contact may not meet the rod contact and the light won't come on. Loosen the wedge screw, push the handle forward and retighten it (420-A steps 18 and 23A).
- Mounting screws working loose while drilling: Unity tells you to check that they're still tight from time to time while you drill the shaft hole (420-A step 10; 4392 step 2f; 8546 step 5a).
- Oversize pilot holes: Unity's inside-pillar sheet says never to drill the mounting holes oversize, and allows opening its 1/8-inch holes to 9/64 inch if the screws are too hard to drive (4392 step 2c). Other sheets use other sizes; the Ford Explorer sheet calls for 5/32-inch holes (8546 step 3b).
Which Unity sheet covers your installation?
| Sheet | Covers | Revision | Find your kit |
|---|---|---|---|
| 420-A | Spotlight and bracket installation (post mount, all vehicles) | Rev. C, 2007 | Find Your Fit |
| 4392 | Inside "A" pillar installation | Rev. G, 2002 | Find Your Fit |
| 3751 | Ford Crown Victoria aftermarket post installation | Rev. C, 2002 | Crown Victoria spotlight page |
| 8546 | Ford Explorer SUV | Rev. A, 2011 | Police Interceptor Utility and Explorer page |
For the full procedure, step by step, see How to Install a Unity Pillar-Mount Spotlight.
Official Unity installation documents
Every value in the table above is read from Unity Manufacturing's own instruction sheets. The sheets are published by Unity and are the authority if a figure here and a figure in the box ever disagree:
- 420-A Rev. C — Spotlight Installation Instructions (PDF)
- 4392 Rev. G — Inside Post Spotlight Installation Instructions (PDF)
- 3751 Rev. C — Crown Victoria Spotlight Installation Instructions (PDF)
- 8546 — Explorer Spotlight Installation Instructions
- Unity literature, instructions and parts documents (index)
Frequently asked questions
What is the torque spec for a Unity spotlight wedge screw?
It depends on the wedge and the sheet. Unity sheet 420-A gives 60–70 in-lb for a curved wedge and 25–35 in-lb for a flat wedge. The inside-pillar sheet (4392) and the Crown Victoria sheet (3751) give 65 ± 5 in-lb, and the Ford Explorer sheet (8546) gives 40 ± 5 in-lb. Use the sheet that came with your kit.
Are Unity spotlight torque specs in inch-pounds or foot-pounds?
Inch-pounds. 60 in-lb is 5 ft-lb, so a foot-pound wrench set to the same number would overtighten the screw twelve times over.
How tight should the bracket set screw be?
50 ± 5 in-lb when the outer-tube bushing has a flat, dimple or groove (Unity sheets 420-A and 8546), and 45–55 in-lb on the Crown Victoria sheet (3751). When the bushing has none of these, sheet 420-A has you tighten the bracket clamping screw or set screw to 60–70 in-lb once the notch orientation is set. The inside "A" pillar sheet (4392) gives no value for its bracket set screw or clamping screw.
Is there a torque spec for the spotlight head set screws?
No. Unity gives no torque value for the two head-housing set screws. Tighten them just enough that the head holds its aim in the wind; overtightening makes the light hard to aim and wears the parts.
Why did my spotlight stop working after I tightened the handle?
The switch contact in the handle probably isn't touching the rod contact at the end of the shaft. Loosen the wedge screw, push the handle forward onto the shaft and retighten the screw while keeping pressure on the handle.
Next step
Need a wedge set or a handle? See the flat-shaft wedge set, the round-shaft wedge set and the U-6701-0101 handle. Fitting a new spotlight? Find the kit for your vehicle in Find Your Fit. Ordering for a fleet or an agency? Request a Quote.
