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How to install a 12 bolt?
This is a discussion on How to install a 12 bolt? within the Drivetrain forums, part of the LSx Technical Help Section category; ...
05-25-2006, 08:29 PM #1
How to install a 12 bolt?
Let's begin by admiring our beautiful 12 bolt.
Rottie not included
To start, commence the usual setup process. Block the front wheels, and jack the rear of the car high in the air. Use a jackstand under each side of the rear subframe rails for the main supports, and then later use 2 more jackstands under the 10 bolt axle tubes to support it for removal. If you opted to buy new backing plates and reluctor rings from Moser, you can remove the rear end without taking the cover or axles off. Remove the wheels. The calipers and hangers can come off together, they are held on with two 15mm bolts on each side. It is not necessary to disconnect the calipers to install the 12 bolt, but be careful not to stress/break the caliperís lines. I simply used a bungee cord to hold the caliper to a hole in the body.
Caliper hanging with a bungee cord
With the caliper out of the way, the rotors pull off if you didnít forget to release your e-brake. To remove the backing plate the axle will need to come out first. Remove the rear cover and let the fluid drain into a receptacle. Rotate the carrier until you see a small 8mm bolt. Depending on your car, it will either have a Torsen rear end (identifiable by the paddle) or an Auburn (which uses an axle pin). Either will slide out when the bolt is removed. If you have a car with ASR, you will need to remove the rear speed sensors from the backing plate, each held on with a 10mm bolt. Then push each axle towards the middle of the car and the c-clip should jingle jangle to the bottom of the housing. After that, the axles can be pulled out.
Removing axle pin bolt on an Auburn carrier
Your rear without the backing plate
If you have ASR, this would be a good time to verify that your wheel speed sensors will fit your new rear end. Obviously the hole in the backing plate is large enough, but often there are clearance problems with the axle tubes. It may take a little bit of grinding to get the sensors to slide in, so grit your teeth, grab hold of that grinder, and start taking away material off your $2k+ investment. I did it while the axle was in the car simply because I didnít have the foresight to do it beforehand.
Take a small bit of material away to fit the sensor
Now we can commence the actual removing of the 10 bolt. There are a few ways to go about this as far as removal of components go, but hereís the rundown of what worked for me.
First a large jack was placed squarely under the rear end, with a slight bit of pressure on it. It would behoove you to remove the caliperís brake lines and any traction control wiring from the rear end first, so it doesnít get hung up on something later. The brake lines are held on mainly by little clips that need to be bent out of the way. Towards the front of the rear there is also a small bolt pinning the lines to the rear end, that must come out too.
Place the jack under the rear, towards the front
Remove the 13mm bolt attaching the brake lines to the rear
Now the brake lines are free to hang
To remove the e-brake cables from the bracket, take a pair of pliers and depress the tabs until it pops out backwards. Slide it back so that the thin, spring-encased part will slip through the small opening in the bracket, and pull it out. From there you can slip the e-brake cable out of anything else that secures it to the rear, then let it dangle freely. The e-brake bracketís bolts can be removed, and the bracket can be tied out of the way.
E-brake cable assembly
Pinch the prongs to remove the cable from the bracket
When everything brake & electrical wise disconnected, the torque arm bolts were removed at the rear end. If you disconnect the torque arm before anything else, it lessens the chance of binding up the bolts later on. With the jack firmly under the torque arm, remove the nuts from the bolts. If they do not easily slide out the top, play around with pumping up/lowering the jack slightly to get it angled just so.
Remove the torque arm nuts, and slip the bolts out
With the torque arm out of the way, you can go to town on the sway bar end-links, lower control arms, and shocks. The control arms can stay mounted to the body, just remove them from the rear end.
The shock's nut is 21mm. When the nut is off, push the shock out of the rear end and let it hang
Swaybar endlinks are 14mm, remove these as well
Remove the LCA from the rear but leave it attached at the body
05-25-2006, 08:29 PM #2
Now do a final once-over to make sure nothing is still attached before attempting to remove the rear end.
This next section is open to any ideas you may have as to what will be the most effective way for you to remove the rear end from the car. If you have a buddy you can simply lower it down and lift it out of the way. If you’re up on a lift you could use a transmission jack. I did my install solo, so I had to get a little creative. It also doesn’t help that my arms are better suited for lifting cookie sheets out of the oven instead of heavy chunks of metal (see, women can make ‘get back in the kitchen’ jokes too!) I used the jack stands to support the rear and lowered them a few notches so the rear could slide out from under the car. I then dragged the rear end out from under the car (looked something like a lion dragging a zebra across the savanna).
Now you see it
Now you don't. Who needs David Blaine when you have Keliente?
Once you have the rear end out of the car, notice where the hole for the brake line clip is towards the front of the 10 bolt. Make a few measurements and drill a similarly sized hole in your 12 bolt. You can either tap that hole and reuse the bolt, or slip a nut & bolt through it to retain the clip. Please disregard the fact that I put two holes in my 12 bolt in an attempt to perform this procedure. I got the old saying, ‘measure twice, cut once’ backwards!
Drilling a hole for the brake lines
If you would like to add fluid to the 12 bolt, now would be a good time. The fill hole is in the same location as stock. Otherwise it should be ready to bolt in. I also took the time to clean up the driveshaft tunnel/rear underneath of the car which had been showered with gear oil from an omnipresent pinion seal leak.
Now you can get your 12 bolt up onto jackstands, a jack, or in your buddy’s hands, and proceed to put it beneath the car. Line it up so that it is fairly close to where it needs to be. The rear components can be re-installed in whatever way is best for you. I positioned the rear as close to the torque arm as possible, and installed those bolts first. Be sure to use loctite on the torque arm bolts. If you decided to switch to an aftermarket torque arm, you will need longer bolts than what Moser supplies.
12 bolt lined up
Moser leaves a tapped hole with a barbed fitting in the top of the axle tube. You’ll need to get a slim piece of tubing and attach it to the chassis somewhere (leaving room for suspension travel). It is a vent tube, and if you don’t secure it properly you will lose fluid out of it.
From here the installation is all downhill. Reconnect the shocks and swaybar endlinks, as well as the control arms. When tightening the control arms, load the suspension. If not, you may experience some popping noises while driving.
Reinstalling the brake lines is rather simple. Bolt the small bracket to the front of the housing, and secure the metal brake lines to the rear in an appropriate manner. For the e-brake cables, you can reuse the metal holders from the 10 bolt (that are inserted in between the rear cover and the rear cover bolts). Slip the e-brake cable back through the hole and bend the prongs slightly so it does not want to slip back out. Attach it to the backing plate. When you first pull the e-brake again don’t panic when it comes all the way up, it is self-adjusting.
Reattaching the brake lines
E-brake cable back in place
If you have ASR, secure the wiring harness so it will not get torn up. I attached mine to the brake line. Reconnect the connectors to the sensors.
To use your sway bar on your new 12 bolt, you will need to pick up a set of 3" exhaust clamps. If you opted for the thick aluminum cover you may have to get a little creative for the sway bar to fit over it.
Exhaust clamps attaching sway bar
Now do a final check - tighten/check all of the bolts, make sure the fluid is topped off, and that the brake lines are secured. Reinstall the rotors, then the calipers & hangers, and finally the wheels. Leave the car on jackstands and now you can proceed to ‘break in’ the rear end as specified by Moser. They recommend letting the car freewheel in a forward as well as a reverse gear for a few minutes each. Recheck the fluid afterwards, and take it for a test drive. Once driving, Moser recommends accelerating/decelerating a few times, and then allowing the gears to cool fully before driving again.
06-01-2006, 03:14 PM #3
06-01-2006, 09:29 PM #4
Maybe my eyes are playing tricks on me or I'm looking at the pic wrong but what is up with that torque arm? Do you have something wrapped around it?
06-02-2006, 08:12 PM #5
- Join Date
- Aug 2005
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Red Tint Jewelcoat
- 2008 Trailblazer SS
Will be referencing this soon enough!2008 Trailblazer SS
Yank PTB3600, Kooks 1 7/8" LT's, 4" intake, E-fans, Magnaflow, Sonnax kit, tranny cooler, tune.
Lowered, HID's, tinted.
1999 Pontiac Trans Am WS.6 #1747 SOLD
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06-02-2006, 08:17 PM #6
excellent write up that will help tons of people. I got a strange with everything already assembled so mine was a piece of cake....for the most part. As I'm doing my installs I always think about you guys that do the write ups with pictures. That's a fair amount of added work to throw in there along with actually doing the swap. Lord knows I don't want to be wagging the camera around while I'm turning wrenches.
06-03-2006, 05:40 AM #7
- Join Date
- Nov 1999
- over here...
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- 1999 trans am
Hey Mods!!! Sticky Time!!!
06-05-2006, 06:47 PM #8Originally Posted by 0rion
06-05-2006, 10:26 PM #9
I've looked at that picture over and over and can't figure out what I'm seeing. It's the 10th picture down with the caption "Remove the torque arm nuts, and slip the bolts out". Is that greyish textured part your actual torque arm? My was smooth. What year is that car? That has to be what it is.
06-07-2006, 05:39 PM #10
My car is a 2000. Some of the cars came with more sound deadening stuff sprayed on the torque arm than others. It's always been like that.
07-11-2007, 10:25 AM #11
Did the driveshaft fit?
The length from the centerline to the yoke seems to about an inch longer on mine.
Want to make sure before I tear into it.
10-12-2007, 07:58 PM #12
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11-02-2007, 08:45 AM #13
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- 1999 Z28 408 Stroker M6
05-03-2010, 08:16 PM #14
mine should b in the middle of this month! yippy skippy! mid 11,s here i come!
04-20-2012, 04:02 AM #15
Nice write up. Looks pretty straight forward from what I can tell. I'm probably going to be attempting this myself here in a few months. Are there any sticking points or commom problems anyone has had doing this themselves? i.e. what are the things that could seriously screw up the install/performance down the road for someone who is attempting this for their first time? I'm no mechanic, but I have done all my mods myself so far with good success. I just dont want to get in over my head and/or seriously screw something up. Anything in particular I need look out for that isnt covered in this write up?
Also, about how long did this take you?
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