Write-Up: Front Subframe/Cradle Mount Mod

Here's a mod I came up with.I hope everyone interested in a better handling car would do this.It promises to add a little harshness to the ride.feels like Nothing more than a few extra lbs of air in the tires.
Its worthy to note that this mod is nowhere close as an upgrade to modifying the RSSA.The RSSA mod will give you alotmore bang for the buck.

Here is a pic of my hockey puck set up.the pucks works ok,but are nowhere near as strong as hard mounting the subframe to the body.in the pic there is a puck on the top of the subframe

I dont show the bottom because its just another puck under the top puck with the SF sandwiched inbetween.
take a 1/8 or thicker plate steel.trace an outline of the puck.it just so happens a pucks diameter is perfect for this.

cut the disks out

take your OEM cup washer and cut the stalk of the washer to about flush with it's outer dia.

after cutting a 3/8 hole in your disks,run the bolt through everything.it will look like this

place your cut cup washer on top of the SF mount spot

make sure its square so that you wont have a prob bolting it all down. and tack it down.you dont have to weld them in,but it will make the set up stronger if you do.
now take your bolt and washer and run it in.the bottom of the washer should rest comfortably against the bottom side of the SF and the bolt,when tightened down shoud not be able to dimple the big washer.the washer should rest nicely against the bottom of the cup washer.the final set up should look like this

The reason you dont see my bolt flush against the underside of the washer is because I dont have any shorter bolts other than the OEM ones that came out of the sub frame.So I used the cut stalks of the cup washers so I can get back on the road.I'll swing by the hardware store and pick up, 4,3.5" shoulder bolts grade 10,and replace the OEMs.Now the cut stalks are just tacked in place to avoid slop.I also used 1/8 steel plate.I have not welded the washers in place because I'll replace them with 1/4" plate when I get some.and then Ill weld them in.super strong..This way all I have to do when I need to service the car is to drop the bolts.no need to mess with a whole bunch of rubber isolator bullshit.this mod does not interfere with the clearances.It will however bring the SF 3/8" closer to the body.No prob.

Do the same for all six and youre in business. This mod can be done up in many different ways.This worked for me.
The OEM cup washer is the best to use against the underside of the body because on top of the cup washer there are tiny little nibs that effectively dig into the body preventing movement.Ya have to take one off to see what I mean.

Great job robo, those subframes were definately not meant to last. But I cant believe a desert car has enough rust to warrant this kind of repair?

I think what robo is doing qualifies more as a mod than a repair. He's stiffening the cushion between the cradle and the chassis in hopes of a firmer ride, which I have absolutely no doubt he achieved!

Yeah. the subframe is in good condition.I just got tired of the mushy front end.Drives nice and taut now.

any more cabin vibration from this robo?

none.the car feels absolutely quiet.it also feels like she has instant drive. whereas before,as with all squishy stuff,it felt like the soft bushings were giving.and they were.she really feels conected to the road now.

I thought I would feel some vibes,I dont.not even in whoops does she feel vibey.round corners I really know what the cars doing.After I replace the soft control arm bushings,my front end will be complete.
only thing after that will be my front coil overs and torsion bar.

So i tried the hockey pucks on the top 4 spots of the subframe.
Quite a nice difference in how the car hold the road and the turn in/out on even normal driving.
I think 50% of the noise and looseness in my front end was fixed by doing this. Probably would have been fixed with just some stock replacement bushings,but the hockey pucks do make it a bit stiffer.

Before the mod i was having an odd steering issue on the highway. the car would wander and drift in whatever direction i last turned hard in. what was happening was the subframe was shifting causing the alignment to change. I was able to visually watch about 1-2 inches of subframe movement when rocking the steering wheel with the car on ramps. Keep in mind my upper bushings were not even that worn and i have 0 rust. (bottoms were rotted)
After the mod there is 0 movement in the subframe when turning. All the input goes to the wheels.
The car also takes bumps better because the suspension takes all the vibration rather than the subframe jiggling around and me feeling it in the steering wheel and floorboard.

All in all well worth the cost ($13) for some hockey pucks. I still plan on replacing the lower bushing with pucks but i wasnt able to get the old bushings out. If the ride becomes too harsh i can always use stock lowers and pucks on top.
Thanks robo for being the guinea pig!

My man! It's night and day.But at some point you should weld in the mushroom spacers along with flat steel plate on the underneath of the cradle.
While you were taking everything apart,did you notice how the solid steel mod would go together?
Yer welcom btw.I will never go back to mush.nevah.

take some pics too of yer hockey puck mod too...

ill upload pics when i finish it. the bottom mounts are a little more time consuming to R&R since they are stuck in place the the pucks should be carved to fit the washer a little.

You dont have to carve anything. the bottom pucks fit right up into the bottom of the cradle.all you need to fab or buy is a fat washer the dia of the puck.the little washer that goes on the bottom should not be reused.it will only put a fat dent into the puck over time and lead to the puck cracking.happened to me. best thing is to buy a 1/4 plate steel and cut out your own washers and then cut a hole for the thru bolt into the cradle. you can even place a big washer on top of the bottom puck.not nessesary to place a washer under the top puck.it will squish into the bottom puck top washer. once everything is in place and you tighten down the bolt,you will squish the pucks and they will form to any indentation of the subframe.effectivly making a nice cozy place for themselves.no carving.
Been there done that. a cracked puck is an ugly thing.

This is exactly what I had to do when changing my cradle mount bushings last year. The passenger side was totally rusted out! Held up great.

Thought i should post this in case anyone else is looking to do this mod.
I would like to say the hockey pucks are good in theory and a great "quick fix" HOWEVER, i will be removing mine tomorrow and going with stock GM mounts.
Over time the pucks tend to loosen up and i have to keep tightening the bolts to re-squish the pucks. This seems to be because the puck rubber density changes greatly with hot/cold weather and with load.
This leads to a noisy front end and a little slop in the subframe over small bumps. It vibrates more than im comfortable with, and coupled with the lowering springs has more harshness than i can put up with.
My second and possibly more important reason for changing them is ALIGNMENT. I took the car in and the mechanic could adjust everything fine except my front caster. it was showing +9° on driver front and +8° on passenger front. The caster is the angle the strut is at in relation to vertical 0° in the wheel well. In other words my driver tire was so far forward the axle was rubbing on the motor mount and the tire was almost touching the fender on turns.
While positive caster is good for performance it can have other problems like pull and obviously the mount hitting the axle isnt good.
The stock GM bushings help hold the subframe centered on an alignment hole. you can see what im talking about in this pic with the mount removed. While the hockey pucks do similar dampening up and down, they give no center support preventing the subframe from sliding along the horizontal plane.


That being said i plan to leave the upper 6 hockey pucks in the car since they are similar design to stock with slightly firmer characteristics. But all 6 lower mounts will be new GM mounts.
So take it as a warning or just my personal experience/opinion, but i do not recommend changing out the bottom subframe bushings with hockey pucks. Not worth the trouble in the long run, just get the right part from the dealer.

Matthew

Yup. is why I hard mounted mine.

Thanks for the heads up, Matthew. Ever since robo posted pics of his cracked pucks, I've cringed at the idea. On a positive note, I've seen great results using pucks for the front engine mount. Over a year and still holding very firm.

AA wrote:

Thanks for the heads up, Matthew. Ever since robo posted pics of his cracked pucks, I've cringed at the idea. On a positive note, I've seen great results using pucks for the front engine mount. Over a year and still holding very firm.

I actually had no problems with the pucks cracking FWIW.

also why i used the mushroom washers by themselves. a big fat washer was put in place of the bottom rubber mounts. happy to report my Riv is as uncompliant as a solid bar of steel.

Scott, have you considered doing this?

Does anyone have a detail of where the bolt threads into? I have never removed the cradle mount in this area and need to know if this has to be done while car is lifted or not.

BKRIV wrote:

Does anyone have a detail of where the bolt threads into? I have never removed the cradle mount in this area and need to know if this has to be done while car is lifted or not.

The bolts thread into the body of the car via a "snap in" nut that sits in a pocket inside the body. You'll have to lift the car up a bit to get the bolts out, yes. If you plan on doing anything at all with these cradle mounts, you have to remember not to take out more than 1 at a time. If you do, you run the risk of having the cradle shift on you, and you'll never get the bolts you just took out back in. The ENTIRE engine/transmission and suspension is bolted to it....

Abaddon wrote:

BKRIV wrote:

Does anyone have a detail of where the bolt threads into? I have never removed the cradle mount in this area and need to know if this has to be done while car is lifted or not.

The bolts thread into the body of the car via a "snap in" nut that sits in a pocket inside the body. You'll have to lift the car up a bit to get the bolts out, yes. If you plan on doing anything at all with these cradle mounts, you have to remember not to take out more than 1 at a time. If you do, you run the risk of having the cradle shift on you, and you'll never get the bolts you just took out back in. The ENTIRE engine/transmission and suspension is bolted to it....

What keeps the nuts from spinning in the pocket?

98riv wrote:

Abaddon wrote:

BKRIV wrote:

Does anyone have a detail of where the bolt threads into? I have never removed the cradle mount in this area and need to know if this has to be done while car is lifted or not.

The bolts thread into the body of the car via a "snap in" nut that sits in a pocket inside the body. You'll have to lift the car up a bit to get the bolts out, yes. If you plan on doing anything at all with these cradle mounts, you have to remember not to take out more than 1 at a time. If you do, you run the risk of having the cradle shift on you, and you'll never get the bolts you just took out back in. The ENTIRE engine/transmission and suspension is bolted to it....

What keeps the nuts from spinning in the pocket?

They're "captive" nuts.

This is the EXACT thing that holds the cradle bolts in place. It sits inside the "frame" in the body. The only reason I have one is because I have a cradle bolt that just spins, and I haven't fixed it yet. It's GM P/N 11609712.
If you have a bolt that is spinning, now you can see exactly what rots out....

Abaddon wrote:

This is the EXACT thing that holds the cradle bolts in place. It sits inside the "frame" in the body. The only reason I have one is because I have a cradle bolt that just spins, and I haven't fixed it yet. It's GM P/N 11609712.
If you have a bolt that is spinning, now you can see exactly what rots out....

Thanks for the picture. What happens if the rear middle ones rots out? Those aren't easily replaceable are they?

98riv wrote:

Thanks for the picture.  What happens if the rear middle ones rots out?  Those aren't easily replaceable are they?

It's actually the rear, REAR ones that are a mofo. I found the access when I did my transmission rebuild. If you de-trim the fender well, you can easily see where the cradle meets the body. On the front side of the body, there's an access hole in the "rail". You can get in there with a pick or a screwdriver to remove that part. The REAR-most one is (obviously) behind it. Getting to it isn't easy. I was just going to cut a square hole just above the mount, then weld it back in place once the piece was replaced.