I am thinking of replacing my stock 12 bolt with an aftermarket 12 bolt. Looking at Moser, but I am wondering if they will have an negative or positive affect on the handling of the car? Any other aftermarket 12 bolts out there you guys would recommend from an handling stand point. I don't really want a canyon carver, but I would like to know if I get a Moser rear how much handling will I give up?

Thanks,

Bart

There is no reason to replace your current 12 bolt unless you are narrowing the rearend and tubbing the car. The housing will not change the handling of the car.

Housings with raised upper ears will increase forward bite (by shortening SVSA), but decrease cornering performance (by moving the RRCH upward, which is already too high "stock")

Housings with raised upper ears will increase forward bite (by shortening SVSA), but decrease cornering performance (by moving the RRCH upward, which is already too high "stock")

Thanks. Do you know how much raised upper ears will decrease cornering performance? Everything seems like a comprimise now days.

The upper ears on my Strange rear end are at stock location. But I will warn you against getting a 9" housing if you are going to add the the center housing braces. the offset rear places a problem with bushings fitting into the shorter upper ear and also with whatever sway bar you having contouring to the belly of the pumpkin.

Can you just not find a 12 bolt?

instead of getting an aftermarket housing that will change nothing, spend the money on parts that will actually accomplish something- the money you'd spend for a shiny new 12 bolt housing and guts could be put towards putting better guts (gears, diff, axles) on your stock housing and leave money for better brakes, springs, shocks, and control arms to accomplish whatever it is you want to accomplish.

Thanks. Do you know how much raised upper ears will decrease cornering performance? Everything seems like a comprimise now days.
You probably would never feel it on the street, but it cause a "jacking" effect when pushed hard, which would result in bad oversteer. If you need a shorter SVSA for forward bite, and your car is lowered, you're better off relocating the lower brackets anyway.

There's 2 basic things happening in relation to your rear roll-center in a corner. The first one is body-roll. A high RC will roll less, so it requires a smaller sway-bar. A low RC rolls more, so it requires a bigger sway-bar (assuming all other things equal)
http://www.chevelles.com/showroom/data/516/ROLL_CENTER1.jpg

The second is what the axle will do in relation to the ground. A higher roll-center will cause a "jacking" effect, which leads to a loss of rear grip. A lower roll-center will keep the axle flatter against the pavement, and more tire on the ground. This effect becomes much more apparent with stickier tires.

http://www.chevelles.com/showroom/data/516/ROLL_CENTER2.jpg

A good balance between the 2 (being able to control the roll, and keep the axle flat) on a Chevelle is about 2-3" lower than where the RC is "stock". Relocating the upper brackets upward, moves the RC upward with it.

Thanks Derek I really appreciate the time you took to explain. One day I will understand this suspension setup better. I don't want a hard core pro touring car, but I want a versatile car. I am redoing the motor, frame, etc and my thought was to beef up the existing 12 bolt, but after looking at the costs I thought maybe I would just go ahead and buy a new housing and axles to get stronger and eliminate the c-clips. I don't like buying something new then learning that I gave up cornering for straight line launches. What I am struggling with is will that Moser 12 bolt in the end really make a difference to me at all?? That is the 64,000 dollar question.

The Moser 12 bolt sure looks to be an awesome unit. But do you really need it? I'm sure it will handle anything you throw at it, tons of HP and hard cornering. Just have to justify the expense. Is your current rearend set up like you want as far as gears, posi, heavy duty axles? The only negative thing I see is the tall upper mounts on the Moser housing, could effect handling a bit. I also heard once that they hit the trunk floor pan on lowered cars? You could probably beef up you original rearend with all new parts, save money, and be just as happy. Decisions, decisions.

I have a moser 12 bolt in my car. There is no issue with clearance of the upper arms. I have not gotten my suspension dialed in yet but I have a track day booked for May 20th to try it out on the road course. From the spirited driving I have done so far the car handles extremely well...in fact if you ignore the weight I don't think it will be that far off my BMW e36 M3 once I get some decent dampers in it.

I had the stock 12 bolt that came with my car but when i crunched the numbers by the time I upgraded the axles, added a trutrack, support cover, powdercoat, and c-clip eliminators I was money ahead to buy the moser and sell the stocker to someone that wanted an original rear. Plus the Moser housing is beefed up in all areas including much heavier pinion bearing monts, heavier axle tubes that are fully welded etc. You also get the ford bearing ends that eliminate the need for leaky c-clip eliminators.

Good point Gary, absolutely love your car by the way. Bart, you can sell your old 12 bolt to help pay for the new kick butt Moser one. Good luck!

I have a moser 12 bolt in my car. There is no issue with clearance of the upper arms. I have not gotten my suspension dialed in yet but I have a track day booked for May 20th to try it out on the road course. From the spirited driving I have done so far the car handles extremely well...in fact if you ignore the weight I don't think it will be that far off my BMW e36 M3 once I get some decent dampers in it.

I had the stock 12 bolt that came with my car but when i crunched the numbers by the time I upgraded the axles, added a trutrack, support cover, powdercoat, and c-clip eliminators I was money ahead to buy the moser and sell the stocker to someone that wanted an original rear. Plus the Moser housing is beefed up in all areas including much heavier pinion bearing monts, heavier axle tubes that are fully welded etc. You also get the ford bearing ends that eliminate the need for leaky c-clip eliminators.

Gary, let me know how the car handles on the road course. I have basically come the same decision that you had about upgrading my 12 bolt. Seems like it is almost as cheap as buying a new rear than upgrading the old one.

I have the stock 10 bolt in my 67 for now... I ordered a Moser 12 bolt and had them put the furd bearing ends that accept the LS1 Camaro factory rear disk brakes with integral parking brake. This way I get factory GM brakes that I can get parts for at any local store.

Something to think about considering you are worried about cornering...is the Moser lighter or heavier than the stock 12-bolt? It sounds like it may be significantly heavier with its 'heavier' everything...

My Currie 9" Ford was 50 lbs less than the 12 bolt I was looking at.

It does work on the track. Detroit truetrac is the way to go.

stock 12 bolt modded + panhard rod = Much Goodness

http://c1.ac-images.myspacecdn.com/images02/50/l_a718ced20fcd4146818264689ab44614.jpg