Moser Install Guide

So you want to know how to install the Moser 12-bolt. Probably the biggest weakness in the Moser is its damn instructions. 95% worthless! I went through several big hassles installing mine, and the few minutes you spend reading this could save you many hours of grief. I just finished up my install, so it is fresh in my mind, and I shouldn't be leaving out much. I did the entire install on jack stands, and with nothing but normal hand tools, so this is something every DIY person should be able to handle. Of course, you don't have to do these sections in the ordered described, and should probably do multiple steps at the same time (such as painting, and working on removing the old rear while the paint is drying). This is the full install on my 94 Formula. It should be accurate for all 4th Gen. V8 F-bodies, both stick and auto cars. The 96+ Firebirds / Camaros with traction control may need to do some extra steps to get it to work. The 82-92 3rd Gen. F-bodies should be able to use these instructions too, but there may be a few differences. The 94-96 Impala guys should have a similar install as well, but this is just a guess. All others; you are on your own!

Let's start by removing the old one. Do you have a breaker bar? No? You better go buy one! I also highly suggest buying a 3/8" to ½" driver adapter for your ratchet. A lot of the bolts are sizes that are common for 3/8" driver sockets, but you will need the extra force gained from a ½" driver. Removing the rear is pretty simple; it just takes some elbow grease.

Jack the car up and place it securely on jack stands. Put the jack under the pumpkin, so that the rear will not fall when you start taking stuff off. Yank the rims, and remove the two bolts that retain the calipers. I suggest using a cut and bent clothes hanger to hang the calipers up and out of the way (helps reduce stress on the brake lines as well). Remove the brake line retainers from the old rear. Flimsy metal tabs retain them; I used a set of side dykes to cut them off. There is also a bolt at the end of the axle housing holding the brake lines on, just wrench that off as well.

Now, remove the panhard rod and sway bar (straightforward process). Unbolt the shocks from the rear. Next, unbolt the lower control arms from the rear, and push them down and out of the way. Now, you will need to remove the driveshaft. This may present a challenge. Remove the two U-bolts that retain it. Try pushing down on it and removing it the way you are supposed to. Mine was rusted in so badly that it wasn't going to come out that way. If it doesn't come out, I'll explain how I did mine a little later.

Now, you need to lower the rear end, using the jack to lower it. It will be a little tipsy on the jack, so be careful! Remove the ABS sensor from the top of the housing (it is held on by one bolt). Your springs are probably about ready to fall out, so just put them somewhere. The perches for the top may fall out too, but that's no big deal. If the stay, leave them in. If not, yank them until it is time to put the new rear in. Remove the two long bolts that hold the torque arm on. If you were able to get the driveshaft off, you are done. Have someone help you carry the old rear end somewhere (junkyard perhaps J).

If you couldn't get the DS off, this is for you. Using a helper, pull straight back on the rear end. This should pop the DS from the input of the transmission. Yank the rear end, w/ DS attached, from under the car. You can beat, pound, or do whatever you need to do to get the DS off.

The 12-bolt comes unpainted and partly un-assembled. First, you need to clean it, inside and out. PLEASE, do this all at once; it will save you a lot of time. For the outside, I used a heavy-duty engine de-greaser. For the internals (this includes axles housing AND the pumpkin internals), I used brake cleaner. Make sure to rinse the outside off well, making sure not to get any water on the inside of the rear. For the inside, I dried it out using compressed air.

Now you need to paint it. You will need to properly mask off several areas. I used plastic I cut from the stuff you lay down when painting the inside of your house. I also used black tape to hold it down and make nice edges. I didn't use masking tape because paint tends to bleed through it w/ a lot of coats, but you can always use it too. Cover the holes for the ABS sensor (top of housing). There is a hole for the vent on the left axle housing. You can either cover it or find a proper sized old bolt to screw into it. Cover the rear end cover and the opening in the axle housings. Lastly, cover the yoke, making sure to also cover the seals to the input shaft.

Paint selection is very important. Please learn from my mistakes. You will need 500-degree high temperature paint. Rustolium and other "undercoat" type paints will discolor under the high heat. You will need one can of primer, one to two cans of paint, and a can of clearcoat. I painted my rear yellow, and this is where my problem arrised. I was able to find Plasti-Kote primer and clear. This is good stuff, and it went on really well. But I couldn't find the paint in yellow. I had to buy Dupli-Color High Temp yellow. Big mistake! First, mixing brands I found out can have a problem w/ the paints bonding. Secondly, the Dupli-Color paint sucks, and is very runny. Follow the painting instructions, and paint. You may want to sand some places to get the paint to bond with the metal. I'll give no more advice in this area since I didn't do a very good job. Luckily, you really can't see the rear once it is under the car anyway, so it's not a big deal.

U-joint. I upgraded to an LS1 driveshaft when I did my rear. The stock steel one was junk. The Moser has 1350 inputs on the yoke. I needed a Spicer/Napa 447X U-joint. It cost $15, but Napa forgot to charge me for it! You can either do this yourself (need a torch, vice, hammer) or just have it done (cost me $6, and did it when pressing my axles). If you use and aftermarket DS, you may need a different U-joint.

Brake caliper mounts. READ THIS, VERY IMPORTANT. I took the wrong of two choices. You need to remove you brake caliper mounts and place them over the axles prior to having the axle bearing and press ring pressed on. You can either yank your old ones off, or buy new ones. I should have bought new ones. They are $40/each from a dealer, and you can find them much cheaper at either a discount dealer or salvage yard. Do this; it will save you a lot of time! You can probably get a pair from a salvage yard shipped for $30.

If you are low on cash, here is your other choice; remove the old ones. I regret doing this. You have to remove your axles to do so. Fine, it shouldn't be a big deal. Drain the rear fluid. You have to remove the C-clips, Pinion bolt, and Pinion Retainer bolt. The first two are easy; the pinion retainer bolt is a 100% PITA. The factory puts Locktite on it to make sure it won't back out. You can not get a socket on it. First, try heating the bolt, and the entire area it bolts into w/ a torch (of course, removing all of the gear lube around this area prior to torching it). Heat it as much as you can. You need a 6-point, closed end, 5/16"wrench (you know, the circle at the end of the wrench, but only 6 points rather than the usual 12). Crank on that mother and see if you can get it off. It you can, that's great. If not, like was the case for me, you are sssoooo screwed. So, how did I get mine out? I haven't (yet). Instead, I drilled into the Pinion bolt w/ a big drill bit until I drilled far enough down to go through the retainer bolt. Took forever and was a ton of work. Buying the caliper mounts will save you a lot of time and effort; just do it!

New bolts. You factory bolts are rusted junk. I went to Lowes and picked up new Grade 8 bolts. I got new bolts for the Panhard rod, and LCA's. I already had new bolts for my shocks (since I have HAL 12-way adjustable shocks, which require new bolts). If using the factory shocks, which have the bolts built in, just but new nuts for them.

The Moser comes with bolts for the torque arm, and is a much better setup than the factory torque arm bolts, since it uses 4 screw-in bolts, rather than two long bolts w/ nuts. Also included are new U-bolts for the driveshaft. There is a fitting for the axle vent that is included. 8 T-bolts are included for the caliper mounts. You will need nuts for these, they are fine thread nuts, but I can't remember the size. You will NEED a 9/16" socket for a ¼" driver to install these. This is a 100% must get item; a 3/8" driver won't fit when you install these nuts. There are also two spacers that are supposed to go between the caliper mounts and the axle housing. Throw those away ASAP (more on that later).

Sway Bar Bushings. If you have an aftermarket sway bar, you may not need these. The factory bushing mounts only have a hole that is wide enough to accept 2.5" clamps. Most aftermarket units have holes that are slotted. The stock sway bars are 19mm, so I need ¾" sway bar bushings. I purchased Energy Suspension bushings. I got the greaseable ones, for $14/pair at Jegs. The greaseable bushings were actually cheaper than the non-greaseable ones, so get them!

Adjustable Panhard Rod (optional). I already had a Lakewood Adjust Panhard rod. My stock rear was off center from the factory, and this was a must for this rear too. I don't like the bushings very well on my Lakewood bar, and would suggest a different brand (I recommend a BMR unit).

Lower control arms (optional). You can do these, traction bars, modified stock LCA's, etc. I still have my stock ones in there, but REALLY need to replace them soon. I have more axle hop than ever, and this is a must item IMO. I'll probably get the BMR adjustable units.

Now you should have everything purchased and ready to go. My list is pretty complete, so you shouldn't have to run to the store for anything (which is VERY important IMO). You will NEED a helper or two for the first part of this. Place the Moser under the car on the jack stand, just like you did w/ the old one. Line it up as best you can w/ the torque arm. Don't try to slide it into the torque arm. Instead, get the holes next to the arm, and push it on from the side (it is open on one side). Put the 4 bolts in, and torque them down. Now re-attach the ABS sending unit to the top of the housing.

Make sure the rear cover is on properly, and torque down to spec (25 lb/ft). Slide the axles into the housings. The axles had stickers on the top of them near the splines (for me at least), and I had to yank those off and clean of the sticker residue. Slide the axles in, which is really easy to do. The Moser comes with spacers; do not use the spacers! They are supposed to go between the axle housing and caliper mounts. But they shift the caliper mounts over enough that when you put your brakes back on, you will have severe brake rubbing problems, so don't use them. Instead, line up the caliper mount w/ the axle housing (w/ the two caliper mount holes towards the back of the car), and place the 4 T-bolts through it. These bolts go through the axle housing and then the caliper mounts; this is the only side they can go in on. Put the nuts on and torque them down. Now fill the rear with gear oil and limited slip lube. Make sure you have no leaks. You could have done this section prior to putting the Moser under the car, but it makes it that much heavier to lug around.

Now, re-attach the Panhard rod to the Moser. You may have to fidget, pound, and whatnot to get it to fit in the bracket. If you have a non-adjustable one, attach the driver's side of it to the bracket on the car. If yours is adjustable, leave it off for now so you can adjust it later.

Attach the new sway bar bushings to the sway bar. This is easy to do. Start by attaching the endlinks to the sway bar, then to their mounting points on the car. Take the C-clamps and attach them to the center of each axle housing tube, and then to the sway bar. Make sure everything is lined up well, and is not rubbing anything or touching the rear end.

If you had an adjustable panhard rod, this is for you. Measure the distance between the wheel wells for each wheel. If they are equal, adjust the panhard rod to slide back up in the way it is. If not, adjust it until the rear end it centered. You will probably need a helper to push or pull the rear end side-to-side to get it lined up properly.


	Joe Brodman's 94 Formula (and other stuff) \| home Moser Install Guide The Big, Bad, Moser 12-Bolt Installation Guide So you want to know how to install the Moser 12-bolt. Probably the biggest weakness in the Moser is its damn instructions. 95% worthless! I went through several big hassles installing mine, and the few minutes you spend reading this could save you many hours of grief. I just finished up my install, so it is fresh in my mind, and I shouldn't be leaving out much. I did the entire install on jack stands, and with nothing but normal hand tools, so this is something every DIY person should be able to handle. Of course, you don't have to do these sections in the ordered described, and should probably do multiple steps at the same time (such as painting, and working on removing the old rear while the paint is drying). This is the full install on my 94 Formula. It should be accurate for all 4th Gen. V8 F-bodies, both stick and auto cars. The 96+ Firebirds / Camaros with traction control may need to do some extra steps to get it to work. The 82-92 3rd Gen. F-bodies should be able to use these instructions too, but there may be a few differences. The 94-96 Impala guys should have a similar install as well, but this is just a guess. All others; you are on your own! Removal: Let's start by removing the old one. Do you have a breaker bar? No? You better go buy one! I also highly suggest buying a 3/8" to ½" driver adapter for your ratchet. A lot of the bolts are sizes that are common for 3/8" driver sockets, but you will need the extra force gained from a ½" driver. Removing the rear is pretty simple; it just takes some elbow grease. Jack the car up and place it securely on jack stands. Put the jack under the pumpkin, so that the rear will not fall when you start taking stuff off. Yank the rims, and remove the two bolts that retain the calipers. I suggest using a cut and bent clothes hanger to hang the calipers up and out of the way (helps reduce stress on the brake lines as well). Remove the brake line retainers from the old rear. Flimsy metal tabs retain them; I used a set of side dykes to cut them off. There is also a bolt at the end of the axle housing holding the brake lines on, just wrench that off as well. Now, remove the panhard rod and sway bar (straightforward process). Unbolt the shocks from the rear. Next, unbolt the lower control arms from the rear, and push them down and out of the way. Now, you will need to remove the driveshaft. This may present a challenge. Remove the two U-bolts that retain it. Try pushing down on it and removing it the way you are supposed to. Mine was rusted in so badly that it wasn't going to come out that way. If it doesn't come out, I'll explain how I did mine a little later. Now, you need to lower the rear end, using the jack to lower it. It will be a little tipsy on the jack, so be careful! Remove the ABS sensor from the top of the housing (it is held on by one bolt). Your springs are probably about ready to fall out, so just put them somewhere. The perches for the top may fall out too, but that's no big deal. If the stay, leave them in. If not, yank them until it is time to put the new rear in. Remove the two long bolts that hold the torque arm on. If you were able to get the driveshaft off, you are done. Have someone help you carry the old rear end somewhere (junkyard perhaps J). If you couldn't get the DS off, this is for you. Using a helper, pull straight back on the rear end. This should pop the DS from the input of the transmission. Yank the rear end, w/ DS attached, from under the car. You can beat, pound, or do whatever you need to do to get the DS off. Prepping and Painting the Moser: The 12-bolt comes unpainted and partly un-assembled. First, you need to clean it, inside and out. PLEASE, do this all at once; it will save you a lot of time. For the outside, I used a heavy-duty engine de-greaser. For the internals (this includes axles housing AND the pumpkin internals), I used brake cleaner. Make sure to rinse the outside off well, making sure not to get any water on the inside of the rear. For the inside, I dried it out using compressed air. Now you need to paint it. You will need to properly mask off several areas. I used plastic I cut from the stuff you lay down when painting the inside of your house. I also used black tape to hold it down and make nice edges. I didn't use masking tape because paint tends to bleed through it w/ a lot of coats, but you can always use it too. Cover the holes for the ABS sensor (top of housing). There is a hole for the vent on the left axle housing. You can either cover it or find a proper sized old bolt to screw into it. Cover the rear end cover and the opening in the axle housings. Lastly, cover the yoke, making sure to also cover the seals to the input shaft. Paint selection is very important. Please learn from my mistakes. You will need 500-degree high temperature paint. Rustolium and other "undercoat" type paints will discolor under the high heat. You will need one can of primer, one to two cans of paint, and a can of clearcoat. I painted my rear yellow, and this is where my problem arrised. I was able to find Plasti-Kote primer and clear. This is good stuff, and it went on really well. But I couldn't find the paint in yellow. I had to buy Dupli-Color High Temp yellow. Big mistake! First, mixing brands I found out can have a problem w/ the paints bonding. Secondly, the Dupli-Color paint sucks, and is very runny. Follow the painting instructions, and paint. You may want to sand some places to get the paint to bond with the metal. I'll give no more advice in this area since I didn't do a very good job. Luckily, you really can't see the rear once it is under the car anyway, so it's not a big deal. Prepping for install: There is a bunch of stuff you need to do/buy prior to installing the Moser. Here is the list: Gear oil. You need a non-synthetic. My rear, w/ the HD support cover, held almost 5 quarts. GM Limited Slip lube. Every GM dealer should have it in stock. This is a must. U-joint. I upgraded to an LS1 driveshaft when I did my rear. The stock steel one was junk. The Moser has 1350 inputs on the yoke. I needed a Spicer/Napa 447X U-joint. It cost $15, but Napa forgot to charge me for it! You can either do this yourself (need a torch, vice, hammer) or just have it done (cost me $6, and did it when pressing my axles). If you use and aftermarket DS, you may need a different U-joint. Brake caliper mounts. READ THIS, VERY IMPORTANT. I took the wrong of two choices. You need to remove you brake caliper mounts and place them over the axles prior to having the axle bearing and press ring pressed on. You can either yank your old ones off, or buy new ones. I should have bought new ones. They are $40/each from a dealer, and you can find them much cheaper at either a discount dealer or salvage yard. Do this; it will save you a lot of time! You can probably get a pair from a salvage yard shipped for $30. If you are low on cash, here is your other choice; remove the old ones. I regret doing this. You have to remove your axles to do so. Fine, it shouldn't be a big deal. Drain the rear fluid. You have to remove the C-clips, Pinion bolt, and Pinion Retainer bolt. The first two are easy; the pinion retainer bolt is a 100% PITA. The factory puts Locktite on it to make sure it won't back out. You can not get a socket on it. First, try heating the bolt, and the entire area it bolts into w/ a torch (of course, removing all of the gear lube around this area prior to torching it). Heat it as much as you can. You need a 6-point, closed end, 5/16"wrench (you know, the circle at the end of the wrench, but only 6 points rather than the usual 12). Crank on that mother and see if you can get it off. It you can, that's great. If not, like was the case for me, you are sssoooo screwed. So, how did I get mine out? I haven't (yet). Instead, I drilled into the Pinion bolt w/ a big drill bit until I drilled far enough down to go through the retainer bolt. Took forever and was a ton of work. Buying the caliper mounts will save you a lot of time and effort; just do it! Put the caliper mount on the axle, then the axle bearing, and then the press ring. This is about the only place in the Moser instructions that is worth a damn. Have it pressed on. Napa did mine for $15/axle. New bolts. You factory bolts are rusted junk. I went to Lowes and picked up new Grade 8 bolts. I got new bolts for the Panhard rod, and LCA's. I already had new bolts for my shocks (since I have HAL 12-way adjustable shocks, which require new bolts). If using the factory shocks, which have the bolts built in, just but new nuts for them. The Moser comes with bolts for the torque arm, and is a much better setup than the factory torque arm bolts, since it uses 4 screw-in bolts, rather than two long bolts w/ nuts. Also included are new U-bolts for the driveshaft. There is a fitting for the axle vent that is included. 8 T-bolts are included for the caliper mounts. You will need nuts for these, they are fine thread nuts, but I can't remember the size. You will NEED a 9/16" socket for a ¼" driver to install these. This is a 100% must get item; a 3/8" driver won't fit when you install these nuts. There are also two spacers that are supposed to go between the caliper mounts and the axle housing. Throw those away ASAP (more on that later). C-clamps. You need 3" C-clamps to clear the larger axle housing. I just used 3" Muffler clamps, and they worked great. Really long zip-ties. You need these to retain the brake lines, as the new rear doesn't have retainer tabs. Sway Bar Bushings. If you have an aftermarket sway bar, you may not need these. The factory bushing mounts only have a hole that is wide enough to accept 2.5" clamps. Most aftermarket units have holes that are slotted. The stock sway bars are 19mm, so I need ¾" sway bar bushings. I purchased Energy Suspension bushings. I got the greaseable ones, for $14/pair at Jegs. The greaseable bushings were actually cheaper than the non-greaseable ones, so get them! Sway Bar End-Links (optional). Your end-links probably look like trash by now, and since you have the sway bar off, you might as well replace these. At $14/pair, they are worth it. I used 2 5/8" ES endlinks, and they worked well. Adjustable Panhard Rod (optional). I already had a Lakewood Adjust Panhard rod. My stock rear was off center from the factory, and this was a must for this rear too. I don't like the bushings very well on my Lakewood bar, and would suggest a different brand (I recommend a BMR unit). Lower control arms (optional). You can do these, traction bars, modified stock LCA's, etc. I still have my stock ones in there, but REALLY need to replace them soon. I have more axle hop than ever, and this is a must item IMO. I'll probably get the BMR adjustable units. Installing the Moser: Now you should have everything purchased and ready to go. My list is pretty complete, so you shouldn't have to run to the store for anything (which is VERY important IMO). You will NEED a helper or two for the first part of this. Place the Moser under the car on the jack stand, just like you did w/ the old one. Line it up as best you can w/ the torque arm. Don't try to slide it into the torque arm. Instead, get the holes next to the arm, and push it on from the side (it is open on one side). Put the 4 bolts in, and torque them down. Now re-attach the ABS sending unit to the top of the housing. Put the springs back on. Place them over their bottom mount, and if the perches fell out, place them on top of the springs. Jack the rear up, and make certain the springs line up properly. Now, re-attach the LCA's and shocks. Make sure the rear cover is on properly, and torque down to spec (25 lb/ft). Slide the axles into the housings. The axles had stickers on the top of them near the splines (for me at least), and I had to yank those off and clean of the sticker residue. Slide the axles in, which is really easy to do. The Moser comes with spacers; do not use the spacers! They are supposed to go between the axle housing and caliper mounts. But they shift the caliper mounts over enough that when you put your brakes back on, you will have severe brake rubbing problems, so don't use them. Instead, line up the caliper mount w/ the axle housing (w/ the two caliper mount holes towards the back of the car), and place the 4 T-bolts through it. These bolts go through the axle housing and then the caliper mounts; this is the only side they can go in on. Put the nuts on and torque them down. Now fill the rear with gear oil and limited slip lube. Make sure you have no leaks. You could have done this section prior to putting the Moser under the car, but it makes it that much heavier to lug around. Now, re-attach the Panhard rod to the Moser. You may have to fidget, pound, and whatnot to get it to fit in the bracket. If you have a non-adjustable one, attach the driver's side of it to the bracket on the car. If yours is adjustable, leave it off for now so you can adjust it later. Install the driveshaft. Put the shaft into the transmission first, the slide the U-joint in the yoke on the Moser. This is a quick and simple task. Not put the U-bolt on that retain the U-joint, and torque them down. Attach the new sway bar bushings to the sway bar. This is easy to do. Start by attaching the endlinks to the sway bar, then to their mounting points on the car. Take the C-clamps and attach them to the center of each axle housing tube, and then to the sway bar. Make sure everything is lined up well, and is not rubbing anything or touching the rear end. Reinstall the brake discs and calipers. Now, use the zip ties to mount the lines to the axle housing as best as you can. Finally, install the wheel and torque them to 100 lb/ft. If you had an adjustable panhard rod, this is for you. Measure the distance between the wheel wells for each wheel. If they are equal, adjust the panhard rod to slide back up in the way it is. If not, adjust it until the rear end it centered. You will probably need a helper to push or pull the rear end side-to-side to get it lined up properly. You are done. Follow the break-in instructions, and enjoy your 12-bolt. Back to Moser 12-Bolt Page