Solid rear sub-frame bushings - M6 guys ALL should do them!

[acammer]

I installed Pegasus solid (aluminum) rear sub-frame bushings on Tuesday. Ever since I bought this car I felt like there was just a obscene amount of slop in the driveline. You hear "well, it's got a two piece drive-shaft, it's got a dual mass flywheel, it's IRS, etc". I always felt like the slop was mostly the rear sub-frame - you could really notice it if you pulled the e-brake on while it was still rolling a little that it would REALLY rock back and forth - and that would only be suspension related.

So, I installed the solid bushings. The install really wasn't too challenging with the use of a lift. I used the heat and jack method, and the whole job took only about two hours. I also swapped on an LPW differential cover - for those of you wondering - YES, you can do it without pulling an axle and dropping the diff out.

Man - wow, what a difference. I felt it from the first release of the clutch backing out of the shop - just everything was solidly connected. Much less potential for bucking, much better shifting feel, pedaling through wheel-spin is nice and smooth, no wind-up on launch, this should be a MUST DO mod for even a stock M6 car. Autos will benefit too, but the M6 especially moves that cradle around a lot! If you're on a tire and you've got aggressive gears, it's the only way to be. It's worth every penny.

Note - I did not pick up any type of road noise at all. No clunks, bangs, etc. I did pick up a good bit of gear whine. My car has 4.10s, and they were not quiet to begin with (has had BMR pro bushings in the diff for a year). I added the LPW cover at the same time as the solid bushings - that has load bolts that go right down to the main caps on the ring gear. And that cover has a BMR pro bushing in it, and then solid cradle mounts, so the noise has a pretty straight shot to get up to the body. I think the LPW cover has a lot to do with it. No complaints though - I'm doing race-car stuff and that's a side-effect I'm willing to live with. I bet most sets of gears aren't this noisy either - most guys say they have no noise.

[bayarea408]

I just picked up a set of pegasus mounts and Z28 rear upper control arm bushings. Ill be attempting it on the floor with 2 jacks and some jack stands.

Glad to hear it made a big difference. cant wait to attempt this myself.

[SSE 4 2SS]

Originally Posted by acammer

I installed Pegasus solid (aluminum) rear sub-frame bushings on Tuesday. Ever since I bought this car I felt like there was just a obscene amount of slop in the driveline. You hear "well, it's got a two piece drive-shaft, it's got a dual mass flywheel, it's IRS, etc". I always felt like the slop was mostly the rear sub-frame - you could really notice it if you pulled the e-brake on while it was still rolling a little that it would REALLY rock back and forth - and that would only be suspension related.

So, I installed the solid bushings. The install really wasn't too challenging with the use of a lift. I used the heat and jack method, and the whole job took only about two hours. I also swapped on an LPW differential cover - for those of you wondering - YES, you can do it without pulling an axle and dropping the diff out.

Man - wow, what a difference. I felt it from the first release of the clutch backing out of the shop - just everything was solidly connected. Much less potential for bucking, much better shifting feel, pedaling through wheel-spin is nice and smooth, no wind-up on launch, this should be a MUST DO mod for even a stock M6 car. Autos will benefit too, but the M6 especially moves that cradle around a lot! If you're on a tire and you've got aggressive gears, it's the only way to be. It's worth every penny.

Note - I did not pick up any type of road noise at all. No clunks, bangs, etc. I did pick up a good bit of gear whine. My car has 4.10s, and they were not quiet to begin with (has had BMR pro bushings in the diff for a year). I added the LPW cover at the same time as the solid bushings - that has load bolts that go right down to the main caps on the ring gear. And that cover has a BMR pro bushing in it, and then solid cradle mounts, so the noise has a pretty straight shot to get up to the body. I think the LPW cover has a lot to do with it. No complaints though - I'm doing race-car stuff and that's a side-effect I'm willing to live with. I bet most sets of gears aren't this noisy either - most guys say they have no noise.

Curious, did you have the factory bushings prior to the solid bushing install.

I went from factory to solid and then to urethane bushings. My car is still solid and connected. Anything is an improvement over the soft factory bushings...

Enjoy that car now since it's hooked up...

[acammer]

Originally Posted by SSE 4 2SS

Curious, did you have the factory bushings prior to the solid bushing install.

I went from factory to solid and then to urethane bushings. My car is still solid and connected. Anything is an improvement over the soft factory bushings...

Enjoy that car now since it's hooked up...

Factory bushings previously. I'm sure poly is pretty good, the factory setup is crazy sloppy.

[bayarea408]

Originally Posted by acammer

I installed Pegasus solid (aluminum) rear sub-frame bushings on Tuesday. Ever since I bought this car I felt like there was just a obscene amount of slop in the driveline. You hear "well, it's got a two piece drive-shaft, it's got a dual mass flywheel, it's IRS, etc". I always felt like the slop was mostly the rear sub-frame - you could really notice it if you pulled the e-brake on while it was still rolling a little that it would REALLY rock back and forth - and that would only be suspension related.

So, I installed the solid bushings. The install really wasn't too challenging with the use of a lift. I used the heat and jack method, and the whole job took only about two hours. I also swapped on an LPW differential cover - for those of you wondering - YES, you can do it without pulling an axle and dropping the diff out.

Man - wow, what a difference. I felt it from the first release of the clutch backing out of the shop - just everything was solidly connected. Much less potential for bucking, much better shifting feel, pedaling through wheel-spin is nice and smooth, no wind-up on launch, this should be a MUST DO mod for even a stock M6 car. Autos will benefit too, but the M6 especially moves that cradle around a lot! If you're on a tire and you've got aggressive gears, it's the only way to be. It's worth every penny.

Note - I did not pick up any type of road noise at all. No clunks, bangs, etc. I did pick up a good bit of gear whine. My car has 4.10s, and they were not quiet to begin with (has had BMR pro bushings in the diff for a year). I added the LPW cover at the same time as the solid bushings - that has load bolts that go right down to the main caps on the ring gear. And that cover has a BMR pro bushing in it, and then solid cradle mounts, so the noise has a pretty straight shot to get up to the body. I think the LPW cover has a lot to do with it. No complaints though - I'm doing race-car stuff and that's a side-effect I'm willing to live with. I bet most sets of gears aren't this noisy either - most guys say they have no noise.

wanted to ask you. What torque specs did you install the pegasus mounts at? Did you buy new bolts or reuse the stock bolts. thanks

[WarDaddy376]

Is this the part number your thread is about PEG-R-CB1 Rear Cradle Bushings (SET)?

[acammer]

Originally Posted by bayarea408

wanted to ask you. What torque specs did you install the pegasus mounts at? Did you buy new bolts or reuse the stock bolts. thanks

3-4 uga-dugas. I did not put a torque wrench to them. The spec calls for 165ft/lbs - that's higher than my 1/2" torque wrench will go anyways, and about where the impact will leave things on kill. I definitely did not buy new bolts, TTY on a head, sure, but on a suspension part, I'm comfortable reusing.

[acammer]

Originally Posted by WarDaddy376

Is this the part number your thread is about PEG-R-CB1 Rear Cradle Bushings (SET)?

Yes - that's the part. Can't recommend them enough - after another couple hundred miles I'm still thrilled with the improvement to the feel of the car. I've made a few "full send" launches with the drag radials and everything seems to be very solid, not a hint of wheel hop.

[WarDaddy376]

Originally Posted by acammer

Yes - that's the part. Can't recommend them enough - after another couple hundred miles I'm still thrilled with the improvement to the feel of the car. I've made a few "full send" launches with the drag radials and everything seems to be very solid, not a hint of wheel hop.

Thank You, I definitely will add to my project list.

[SoFlaZ]

Do you have any other mods to your rear suspension like trailing arms, toe links, bushings etc?

If that's all I need to eliminate hop, that's my next mod. I put on NT555R's for the track and holy wheel hop I couldn't even do a burnout.

I have a 3.91 diff ready to go in with BMR mounts so the rear will be solid too. (I failed to research how to get the stocks mounts out, big mistake)

[acammer]

Originally Posted by SoFlaZ

Do you have any other mods to your rear suspension like trailing arms, toe links, bushings etc?

If that's all I need to eliminate hop, that's my next mod. I put on NT555R's for the track and holy wheel hop I couldn't even do a burnout.

I have a 3.91 diff ready to go in with BMR mounts so the rear will be solid too. (I failed to research how to get the stocks mounts out, big mistake)

Only other suspension mod is BMR pro differential bushings. Maybe some day I'll do more, but for now I'm really happy with how it feels.

[SSE 4 2SS]

Originally Posted by SoFlaZ

Do you have any other mods to your rear suspension like trailing arms, toe links, bushings etc?

If that's all I need to eliminate hop, that's my next mod. I put on NT555R's for the track and holy wheel hop I couldn't even do a burnout.

I have a 3.91 diff ready to go in with BMR mounts so the rear will be solid too. (I failed to research how to get the stocks mounts out, big mistake)

A solid feel and wheel hop are not necessarily related.

Here's an easy way to relate to wheel hop in an IRS.

Hold your arms straight out to your side.... With your hands pointed straight out as well..

Now, you come off the clutch and hammer the throttle.... (represented by your arms moving forwards at the shoulder) Without the solid axle, your wheels try to drift forward flexing at the center section.... Trailing arms prevent this movement.... When your arms come forward, it throws off the alignment of the wheels and they load up until the tires break loose. When the tires breaks loose, (represented by your arms flipping back to a point straight out from your body) the tires stops spinning momentarily until they creep forward again and break loose again..... This can happen over and over very rapidly and this is wheel hop of one cause....

Now on to your hands.... When you drop the clutch and hammer the throttle, the wheels try to creep forward at the hubs, (this is represented by your wrist bending forwards) The get out of alignment, the tires breaks loose, and then flip back to their normal position, and repeating this over and over very rapidly is wheel hop of another cause. Toe rods control this form of flex....

A third is the hop caused by the flexing of the rear cradle doing about the same thing. To reduce the incidence of wheel hop as much as possible, the full package needs to be used.

Welcome to IRS troubles.... The flip side is you don't see many videos of Camaro's spinning out and ending up in crowds due to the stability of the IRS under most conditions.... It was designed more for handling than it was for launching a car at the drag strip. But it can be fixed.

[DrkPhx]

I agree with your observation. I installed them last year and they really tightened up the rear with little to no increase in NVH. I also have a Pfadt rear sway bar, Z/28 upper control bushings and Pegasus trailing arms. No rear end kick out or wheel hop whatsoever.

[acammer]

Originally Posted by SSE 4 2SS

A solid feel and wheel hop are not necessarily related.

Here's an easy way to relate to wheel hop in an IRS.

Hold your arms straight out to your side.... With your hands pointed straight out as well..

Now, you come off the clutch and hammer the throttle.... (represented by your arms moving forwards at the shoulder) Without the solid axle, your wheels try to drift forward flexing at the center section.... Trailing arms prevent this movement.... When your arms come forward, it throws off the alignment of the wheels and they load up until the tires break loose. When the tires breaks loose, (represented by your arms flipping back to a point straight out from your body) the tires stops spinning momentarily until they creep forward again and break loose again..... This can happen over and over very rapidly and this is wheel hop of one cause....

Now on to your hands.... When you drop the clutch and hammer the throttle, the wheels try to creep forward at the hubs, (this is represented by your wrist bending forwards) The get out of alignment, the tires breaks loose, and then flip back to their normal position, and repeating this over and over very rapidly is wheel hop of another cause.

A third is the hop caused by the flexing of the rear cradle doing about the same thing. To reduce the incidence of wheel hop as much as possible, the full package needs to be used.

Welcome to IRS troubles.... The flip side is you don't see many videos of Camaro's spinning out and ending up in crowds due to the stability of the IRS under most conditions.... It was designed more for handling than it was for launching a car at the drag strip. But it can be fixed.

I agree with all of that. I would say that the subframe bushings have the most slop and give of all the rear end components, and are the best place to start. If you fix everything but those, you probably still won't be happy. But if you do them first, you may find you've done all you need.