Rear Subframe Bushing Gap???

#1

As stated in anther thread I got my outside RTAB’s tight. While in there I noticed a gap between by the upper sub-frame busing and the unibody or the car. That just did not look like a place a gap should be. So I dropped the lower plates that hold the whole assembly together, levered the subframe down a bit and then jacked it back into place and retorqued the nut. I did this on both side to keep things level. I was hoping this would close the gap. It did not. Oddly enough the gaps on the passenger side were different than the drivers side. Had a slight gap at the upper section of the bushing and a smaller gap on bottom.

This car came with the Black PowerFelex subframe bushings.

What could be causing the gap? Top busing too small? Inner steel collar too long? Is a gap supposed to be there? Never had a sub-frame out of a car yet.

Do I need to drop the sub-frame to diagnose? Hope not as the only things I had left on my list to do was reinstall my axles and change fluids for the season start.

I will add a few pic as well. The finger you see is from a 5 year old so the drivers side gap is easily a half inch.

Learn your head left to get the correct perspective.

Drivers side upper gap (half inch):

[attachment=1376]IMG_0640.JPG[/attachment]

Drivers side lower gap (none at all):

[attachment=1377]IMG_0643.JPG[/attachment]

Passenger side upper gap (about a quarter inch:

[attachment=1378]IMG_0641.JPG[/attachment]

Passenger side lower gap (about an eighth inch):

[attachment=1379]IMG_0644.JPG[/attachment]

#2

That is not normal or correct. If the subframe bolt is tight, I’d suspect that the bushing sleeves are too long.

#3

Doesn’t the top of the sleeve go up into a hole in the body to position it? It may be that this is not happening. Would be equivalent to a too long sleeve.

Michael

#4

It is possible that the sleeve isn’t going into the pocket in the chassis. But my recollection is that the engagement of the sleeve and pocket is almost 1" and the pictures suggest that the error is less than that. Unless something is preventing the sleeve from fully seating, the only other reason would be sleeves that are too long.

The subframe is going to have to come down to figure out what is wrong.

#5

Thanks for the input. Yes Jim that gap is just shy of a half inch. I had a feeling it was not right and dropping the sub-frame would be the only way to figure it out. Guess my To Do pr-season to do list just grew.

I have not had a sub-frame down yet so I was not sure if the sleeves had a pocket they dropped into or not. Looks like I get to drop the sub-frame to figure this out. Mind as well replace the brake lines while I am in there since they are so hard to get to and I am not sure how old they are. You never know what is under the braided steel lines.

I will update you after its all pulled apart.

#6

OK so the subframe came down this weekend. Seems like the inner collar may be too long but even if it is shorter I am still not 100% sure how these PowerFlex race bushings are supposed to work.

It looks like the inner collar was engaging the sleeve in the body of the car.

Drivers side bushing shot. You can see the wear mark where it was engaging on the sleeve in the car. The collar seems a mm or two to long
[attachment=1386]IMG_0649.JPG[/attachment]

Here is a shot of the mounting point on the car. Its about a cm or so deep.
[attachment=1387]IMG_0651.JPG[/attachment]

Here is a shot of the bushing held in place w/o the top part of the bushing.
[attachment=1388]IMG_0647.JPG[/attachment]

Shot with top part on the bushing.
[attachment=1389]IMG_0648.JPG[/attachment]

The inner collar measures 104mm. Anyone know the correct length this collar should be. I looked at the AKG two piece bushing design and the collar sticks out on them as well on top. So it would also have a gap at the top like mine. Is the subframe supposed to be able to move up an down a bit for compliance?

Would love to get this right and get the car back together for the first even if possible.

Thanks for your input.

#7

Quick update.

I spoke to PowerFlex and they confirmed I had the right parts and the inner collar should be 104mm. They said the inner part of the receiver may have some crud in it and to make sure it was clean. It was clean and I decided I don’t like this design.

So I got some AKG sub-frame bushings and like the design better. Their inner collar measures in at 101.5 mm. I spoke to the owner and he said they do that so the bushing gets a good squeeze by the receiver in the body and the plate below to ensure a good tight fit and minimal sub-frame movement.

#8

I did mine recently… I recall my AKG’s having a taper on one end of the sleeve which went up in to the chassis. The top tabs/sleeve from the stock bushings broke off in to the chassis and I had to drill and chisel it out, was pita. If you dont clean it out the new sleeve will NOT seat! Also the new 2pc AKG bushings does NOT seat flat on the chassis. I called AKG and they confirmed that this was right. I also reused that large washer between the chassis and top of the bushing, they said that didn’t make a diference, in or out.
Note: If your installing the camber/toe weld-ins… cut the top edge of the bushing to gain access to the adjusting nut/bolt.

#9

Oops…where is the big round washer that goes on the top of the AKG?

I think that washer dimension will be your answer.

Geez…it is a bear to remember and reinstall all those parts during a rebuild. Ask me how I know.

RP

#10

So the stoppers (part# 33331127496) arrived today e.g. larger washer mentioned above and not to be found on my car at all, thanks for the attention to detail previous owner. They go around the bushing sleeve and provide a barrier between the bushings and the steel nub that sticks out of the uni-body.

So this part is absolutely critical for the power-flex bushing design to work correctly as it would prevent the sub frame from sliding up the bushing and would fill in the 2mm gap the longer sleeve of the Power-flex design.

Taking this into account I can presume every E30 has a small gap above the bushings / stopper.

If you run supper hard poly / aluminum bushings you could skip the stopper if your sleeves are shorter than 104mm. But then the steel nub would wear into the sub-frame bushings over time so why not pop the $16 bucks and get two new stoppers and protect your $100 bushings.

Replaced a few corroded hard lines (real joy to bend up)so I am ready for reinstallation. Glad that is sorted out. If I get a few minutes I will shoot a few pics for people to reference in the future and to see if difference in busing design.

#11

Can you post a pic of this washer in place?

#12

Sure I will try to get some pics up this week before I go away. Getting my hands on the washer made the design of the Powerflex busing make sense to me.

#13

So here are a few pics to compare AKG to PowerFlex and to see the “Stopper” referenced above.

Side by side. You can see the AKG sleeve is a bit shorter than the PowerFlex. AKG with Stopper and the bushings takes all of the pressure from the mounting rod and nut when installed.

[attachment=1414]IMG_0673.JPG[/attachment]

You can see how the Stopper fits on the sleeve.

[attachment=1415]IMG_0674.JPG[/attachment]

Once piece design of PowerFlex. W/O the stopper the subframe will slide up the bushings. Not good.

[attachment=1416]IMG_0675.JPG[/attachment]

Another shot of the PowerFlex design.

[attachment=1417]IMG_0676.JPG[/attachment]

So if anyone wants a good deal of a set of PowerFlex race bushings just let me know.