https://www.spohn.net/support en-us https://www.spohn.net/support ActiveKB NX tech@spohn.net Sat, 11 Apr 2026 12:21:04 EDT 20 https://www.spohn.net/support/questions/1/ https://www.spohn.net/support/questions/1/ Vehicle Set-Up: Make sure your vehicle is at ride height - suspension loaded. You can not have your rear end "hanging". The vehicle does not have to be level, no matter the angle of the car you're still measuring the difference between the two angles. Setting Pinion Angle There are two angles to deal with: 1) Driveshaft angle 2) Pinion angle You subtract pinion angle from driveshaft angle to get TRUE pinion angle, here's how you do it: First, had you measured your stock drive shaft angle and pinion angle you would have calculated a 0 degrees TRUE pinion angle. This is how all cars come from the factory. Using an angle finder place it on the underside of the driveshaft and record the angle indicated from the driver's side of the vehicle. Next, place the angle finder under the flat surface of the pinion yoke (this surface is parallel with the pinion shaft) and record the angle indicated. Record both angles from the driver’s side of the vehicle. On the driveshaft anything to the left of 0 is positive, on the rear end anything to the right of 0 is negative. Subtract the pinion angle from the driveshaft angle. The result is "TRUE Pinion Angle". In order to apply preload you need negative TRUE pinion angle. Adjust so that the front of the pinion goes down; continue to check each angle until the pinion angle is more degrees down than the driveshaft angle. We recommend –1 degrees on a mildly modified daily driven car. For high horsepower applications we have gotten the best results with –2 degrees. There is no reason to run more negative angle than that, it will actually hurt your performance because it will induce driveline bind. Here's a tip. When adjusting for your TRUE pinion angle, count the number of flats (or the 1/6 of a turn) as you turn the adjuster, to know how many turns it takes to adjust 1 degree of negative TRUE pinion angle and in what direction (clockwise, or counter-clockwise). Once you know that, then adjusting the arm at the track or before a race will take almost no time, and no angle finder will be needed. Adjusting your Spohn Arm: You adjust the pinion angle by turning the pinion angle adjuster either clockwise or counter-clockwise. As you turn the adjuster you will see the pinion nose of the rear housing moving up/down. Moving the rear housing's pinion nose down will give you more of a negative pinion angle degree, and up will give you more of a positive pinion angle degree. You will quickly learn that it does not take many turns to adjust the angle by several degrees, so go slowly and check your angles often. Example: From the driver's side of the vehicle you have 1 to the left of 0 (positive 1) underneath the driveshaft. You have 3 to the right of 0 (negative 3) under the pinion yoke. +1 minus -3 = -2 Spohn Performance Fri, 21 May 2010 18:51:34 GMT https://www.spohn.net/support/questions/277/ https://www.spohn.net/support/questions/277/ This article is a master list of links that will answer any question you may have about ordering a new aftermarket rear end. If you still have questions after reviewing these articles feel free to shoot us an email or give our tech line a call at 1-888-365-6064. Ordering A Rear End - The Master List of Frequently Asked Questions I'm ordering a rear end, what is the difference between the different center section differential types? (article link) How to measure and order a custom length rear end (article link) What is the difference between Pro and Street gears? (article link) Can I order a rear end with a spool and keep my ABS on my 1993-2002 F-Body Camaro & Firebird? (article link) How do I know if I have 3 channel or 4 channel ABS on my 1993-2002 F-Body Camaro & Firebird? (article link) Can I use 4th Gen rims with no spacers on Moser or Strange rear ends on my 1982-1992 F-Body Camaro & Firebird? (article link) What rear brakes can be installed on the new rear end? (article link) What gear oil should I use in my new rear end? (article link) I'm ordering a Strange rear end for a 1998-2002 F-Body. Where should I send my stock brake backing plates? (article link) Do you carry rear ends for applications other than what you have on your website? (article link) How do I know what spline axles and center section I will need? (article link) What is the difference between the 12 Bolt, Ford 9" and Dana 60 rear ends? Which should I get? (article link) What rear end gear ratio should I run for my application? Gear ratio calculator (article link) Which wheel studs do I need for my car when ordering a rear end? (article link) What's the difference between chrome & aluminum rear end covers on 12 Bolt & Dana 60 rear ends? (article link) I'm ordering a rear end for a 1982-2002 F-Body Camaro Firebird, do I need the sway bar installation kit? (article link) I'm ordering a rear end, do I need the conversion u-joint? (article link) I'm ordering a rear end, do I need the control arm relocation brackets? What are they? (article link) I'm ordering a rear end, what is the difference between a bare and powder coated housing? (article link) What is the difference between standard and gun drilled axles? (article link) I'm ordering a rear end, what is the difference between axle flanges? Standard, Star & Lightening Holes? (article link) I'm ordering a Ford 9" rear end, what is the difference between a nodular iron and an aluminum center section? (article link) I'm ordering a Ford 9" rear end, do I need the fill and drain bungs installed? What are they? (article link) I'm ordering a Strange rear end, do I need the standard or chrome moly pinion yoke? (article link) I'm ordering a rear end, does it come with the housing bushings for the rear upper control arms installed? (article link) What is the difference between the M9 and a standard Ford 9" rear end housing? (article link) How can I get a shipping price quote on a rear end? (article link) I'm ordering a rear end, how long does it take to ship out? How does it ship? (article link) I'm ordering a rear end, is there any warranty on them? (article link) I'm ordering a rear end, do I need to specify no c-clips or use a c-clip eliminator? (article link) I'm ordering a rear end, will I need to get a new driveshaft? (article link) I'm ordering a rear end, will the bolt pattern match my vehicle type? (article link) What size wheels and rims fit over the 11" rear drum brake kit for aftermarket rear ends? (article link) Can I get an aluminum rear cover on a Strange Engineering Dana 60 rear end for a 1982-2002 GM F-Body Camaro & Firebird? (article link) I'm ordering a rear end, what are the brake line, emergency brake cable and brake line clamp options? (article link) I'm ordering a rear end, what is the back brace option? (article link) What is a full floater rear end? (article link) I have aftermarket disc brakes for my factory rear end, will they fit on an aftermarket Moser or Strange rear end? (article link) Spohn Performance Wed, 05 Aug 2015 18:43:18 GMT https://www.spohn.net/support/questions/276/ https://www.spohn.net/support/questions/276/ Rear End Center Section Differential Choices Explained Spool: Spools are used in drag race only vehicles. A spool permanently locks both axle shafts together so that both rear tires will always turn at the same speed. They are not designed or intended for street driven vehicles. A spool is much lighter than a standard posi unit and they improve ring and pinion gear life by providing a more rigid gear mounting. A spool is a very strong center section that will hold up to very high horsepower. They are recommended for a pure drag race only race vehicle. Spools are an option on Ford 9", 12 Bolt and Dana 60 rear ends. Eaton Limited-Slip Posi: Superior rebuildable design, race-bred carbon friction discs and automatic LSD. The Eaton Posi LSD is the perfect way to control traction in all types of tarmac running cars. The Eaton Posi LSD prevents wheel slip before it can get started. To do that, carbon disc clutch packs, preloaded by a central spring assembly, are located behind each differential side gear. When torque input increases the clamping load on the clutch packs increases. That causes the chatter-free clutch packs to grab and transfer power to the other wheel. Muscle cars should look to Eaton's limited-slip differential for their traction answers. And the fact is, Eaton's Posi units are virtually bullet proof. A great choice for an all around street driven vehicle. Eaton posi units are an option on 12 bolt rear ends. Detroit TruTrac Torque Proportioning Differential: Smooth operation, performs open until needed and fully automatic limited slip. The Detroit Truetrac was the first helical gear differential ever introduced into the automotive aftermarket as an Eaton brand. It remains the leading helical gear-type limited slip differential in the industry. Detroit Truetrac's proven helical gear design eliminates the need for wearable parts, resulting in maintenance free traction recognized not only for its toughness, but its smooth and quiet operation as well. Proven design and effective performance make the Detroit Truetrac the ideal choice for a wide variety of applications. No maintenance - Just Traction. A great choice for a high horsepower street/track vehicle. The TruTrac is an option on Ford 9", 12 bolt and Dana 60 rear ends. Wavetrac®: One of the known shortcomings of a typical torque biasing differential is its loss of drive (behaving much like an open diff) under zero or near-zero torque conditions (for example, when there is 'no-load' applied through the drivetrain, either at vehicle stationary and/or transition from engine driving vehicle to engine braking and back). The Wavetrac® differential uses a patent pending design to improve grip in low traction conditions. Precisely engineered, converging / diverging wave profiles are placed on one side gear and its mating preload hub. As the two side gears rotate relative to each other, each wave surface climbs the other, causing them to move apart. This imparts an increased normal force through the side gears, increasing the bias ratio as a function of load. This increase occurs automatically only when conditions find it necessary, and it 'reverts' back to its nominal bias ratio quickly and seamlessly, maintaining optimal drivability and performance at all times. It's like having two differentials in one: you get the benefit of a higher bias ratio when needed without detriment to the car's handling. The Wavetrac® differential is an option on Ford 9" and 12 bolt rear ends. Read a detailed description of the Wavetrac® differential at this link. Trac-Loc Limited-Slip Posi: The Trac-Loc Limited Slip Differential is designed as a direct replacement for the hard to find expensive OEM unit, or for those enthusiasts desiring to convert to a limited slip. Available for Ford 9" rear ends, this nodular steel casting is totally rebuildable, includes nickel steel side gears and pinion gears, and multiple plate 360-degree steel clutches. This extremely tough and durable differential houses 400-ft/lb static springs, and is capable of 150 lb. braking torque. Auburn Limited-Slip Posi: The highly efficient torque transfer capability of the Auburn limited-slip differential is achieved through the use of cone clutches coupled to beveled side gears. As torque is transmitted through the differential side gears to the axle shafts, the side gear separating forces and spring pre-load firmly seat the cones into the differential case. The cone design, along with the applied force, determines the torque transfer capability of the differential. When torque levels decrease, as in a cornering maneuver, the gear separating forces also decrease, allowing the axle shafts to rotate independently. It is designed to provide the maximum amount of torque transfer without compromising the performance requirements of a vehicle in situations where torque transfer is not required. A great posi for a performance street vehicle. The Auburn differential is an option on Ford 9" and 12 bolt rear ends. Detroit Locker: The legendary Detroit Locker began the revolution in performance differentials and still leads the industry today. The Detroit Locker is the most durable and dependable locking differential available. The Detroit Locker maximizes traction by delivering 100% of the torque to both drive wheels. It is engineered to keep both wheels in a constant drive mode, and has the ability to automatically allow wheel speed differentiation when required. No other performance differential has the reputation for delivering traction in mud, snow, rocks and on the track. The choice of professional racers and off-road enthusiasts around the world. The durability of the Detroit Locker is unmatched! The Detroit Locker is an option on Ford 9" rear ends. Spohn Performance Mon, 26 Sep 2011 00:06:23 GMT https://www.spohn.net/support/questions/29/ https://www.spohn.net/support/questions/29/ Polyurethane bushing manufacturers advise to never use a petroleum based grease for poly bushing lubrication. Polyurethane should only be lubricated with one specific type of grease to insure long bushing life, and squeak-free performance, Silicone based synthetic water-proof grease. We've found this grease to be so good, we use it for the entire chassis lubrication on the cars we build and race out of our shop. It stays where you put it and doesn't wash away. This grease can be very hard to find at your local stores. This grease is available from Spohn Performance, it's our Part #902, click here to check it out. Spohn Performance Wed, 05 May 2010 01:56:32 GMT https://www.spohn.net/support/questions/31/ https://www.spohn.net/support/questions/31/ A common misconception is that chrome moly is lighter than mild steel. Given the same o.d. and wall thickness a chrome moly tube weighs the same as a mild steel tube. Chrome moly is the abbreviation for "chromium molybdenum", and it is an alloy steel. It was designed for and is used extensively in the aircraft industry due to it's high tensile strength and torsional load ratings. Because of it's higher strength (almost double that of mild steel), it is possible to use thinner gauge tubing when building a product which provides for less weight, or a product that is the same weight but nearly twice as strong. On our products chrome moly tubing is offered for increased strength and/or lighter overall weight for extreme applications. Another misconception is that chrome moly will "crack" and not have long term durability. The stories you may hear about this normally boil down to one thing, it was not properly welded. We have extensive experience in TIG welding chrome moly using industry standard practices and have never had any durability issues. At Spohn Performance we do not cut corners on quality! Spohn Performance Mon, 03 May 2010 14:38:38 GMT https://www.spohn.net/support/questions/37/ https://www.spohn.net/support/questions/37/ Single Adjustable shocks mean that when you adjust the shock looser or stiffer you are adjusting both the rebound and the compression together, the shock will be loose or stiff both ways. Double Adjustable shocks mean that you are adjusting the rebound and the compression independently. You could adjust the shock to have a loose rebound for great weight transfer and a stiffer compression for a more controlled landing. Double adjustable shocks give you the most shock adjustment control of any other choice. "R" Series front shocks are adjustable just like a single adjustable front shock but the compression adjustment range is stiffer. This allows you to set the shock to a 90/10 type setting at the drag strip and go back to a stock shock type setting when driving on the street. They are designed for front drag racing applications to maximize weight transfer. For more detailed information with shock dyno charts see the .pdf file attached below. Spohn Performance Wed, 13 Jul 2011 16:28:13 GMT https://www.spohn.net/support/questions/255/ https://www.spohn.net/support/questions/255/ The main difference between a GM 12 bolt rear end, the Ford 9" rear end and the Dana 60 rear end is the size (and strength) of the ring gear. The 12 bolt rear end has a 8.875" ring gear, the Ford 9" of course has a 9" ring gear and the Dana 60 has a massive 9.75" ring gear. Obviously, the strongest rear end is the Dana 60. Which do you need? That's a question we get asked often, and there's really no right answer. It mostly just boils down to preference. We'll give you a few opinions to guide you. You don't want a rear end that is any bigger and heavier then what you need. If you have a car making 450 RWHP, you don't need the added bulk and weight of a Dana 60. Many GM guys refuse to put a "Ford" product under their car, and that's cool too. If you have a street/strip car making under 700 horsepower the 12 bolt will serve you very well. If you have over 700 horsepower, then we'd recommend a 9" or a Dana 60. The 9" is very easy to work on and can be easily disassembled with simple hand tools. It's also very easy to pull the center section in and out for guys who want to run different gear ratios depending on what they're doing with the car, another big advantage to the 9". The Dana 60 is a monster, if you have a big horsepower car then you can't go wrong with the Dana 60, drop it in and forget about it. Spohn Performance Wed, 09 Feb 2011 20:34:43 GMT https://www.spohn.net/support/questions/16/ https://www.spohn.net/support/questions/16/ Adjustable rear lower control arms are not used to adjust pinion angle and are not required if lowering your ride height. We offer adjustable rear lower control arms (LCAs) to allow for two things. For those installing very large tires they allow you to push/pull your rear end front/back to gain the tire clearance you need in the wheel well. Secondly, many fabricated aftermarket rear ends do not always have the control arm mounts welded on "perfectly". The adjustable LCAs allow you to square up your rear end. With adjustable LCAs and Panhard Bar installed you can do a four wheel alignment to get a perfectly square set up. Many of our LCAs only come adjustable due to the fact that the mounting ends are threaded (rod ends, Del-Sphere, etc.). You may desire these mounting ends but don't feel you need the adjustment feature. Know that all of our adjustable components ship to you jig set at OEM length. If you have no desire to do any adjusting, simply install them as they are shipped and you will be good to go. Spohn Performance Tue, 04 May 2010 14:14:52 GMT https://www.spohn.net/support/questions/220/ https://www.spohn.net/support/questions/220/ Capacity: Aftermarket rear ends will take between 3-4 quarts of gear oil. So when purchasing gear oil for your rear end you will need to purchase four quarts.Moser Engineering & Strange Engineering Rear Ends: The limited slip differential design has been extensively tested with high quality non-synthetic 80W90 hypoid oils (regular mineral based oil) treated with GM or Ford friction additives (3 oz. of additive will treat 1 quart of oil). To avoid differential clutch chatter (noise) and for optimum performance, use the oil and additive described above. Use of other additive and oil types may cause differential clutch chatter. Ford Friction Additive: Part# C8A219B546A GM Friction Additive: Part# 1052358 Strange Engineering Rear Ends: Strange Engineering rear ends are supplied with their recommended limited slip additive. You do not need to purchase limited slip additive when ordering a Strange Engineering rear end, it will come with the rear. Spohn Performance Fri, 27 Jul 2018 13:41:33 GMT https://www.spohn.net/support/questions/226/ https://www.spohn.net/support/questions/226/ 1993-2002 GM F-Body Camaro and Firebird cars came from the factory with 30 mm front and 19 mm rear sway bars.For the 1982-1992 GM F-Body and most other vehicles the diameter of the sway bars varies depending on the vehicle's model, options and package.The best thing to do is measure the diameter of your sway bar using a caliper. To get an accurate measurement be sure to measure on a straight portion of the sway bar away from any bends where the bar deforms from bending.If you do not have a caliper, another crude but fairly accurate way to get a measurement is to tighten an adjustable wrench around the sway bar and then measure between the wrench flats with a tape measure. Spohn Performance Wed, 09 Jun 2010 16:57:09 GMT