Subframe swap project

#1

Am swapping the subframe from eccentric rtabs to the weld-on toe/camber kit. Also going to aluminum subframe and diff bushings. Last night I pulled the diff. Took 2 hrs which is about half the time it took me the first time I did pulled the diff.

Diff studs. A while back someone told me about replacing the top two diff bolts with studs and then putting holes in the trunk floor for easy access. If you’ve not installed a diff, trying to get those bolts started, holding the 75lb diff in place is a SOB. Last night I looked around for 30-35mm long 12MX1.5 studs, 8.8 grade or better. I couldn’t find any. I think that I’ll have to buy bolts and cut them.

Loose bolts. The 4X diff bolts and the UJoint bolts weren’t all that tight. Certainly not as tight as I had torqued them down a couple yrs ago. They’ll be going back in with locktite. One of the bolts that holds the speedo sensor in was only finger tight for crying out loud.

Get a good seat in the half shaft CV bolts. I found that the CV joint bolts, which take an allen wrench not a box end wrench tend to collect debris. You have to clean them out carefully, otherwise the allen wrench socket won’t go in all the way. And if its subtle you could easily end up rounding the hex socket of the bolt. Getting the bolt out would then be a great big pita. So clean out the inside of the hex surface and then tap the hex socket in so you’re sure it’s seated all the way in.

#2

It is a lot easier to drop or install the subframe with the diff attached.

#3

…so when we hear whining at CMP you can blame it on driveline noise transmitted to the tub? :laugh: :woohoo:

#4

Ranger, I just swapped out my dif and have an extra used set of the four top bolts… let me know if you want me to mail them to you.

#5

Hmm. So you unbolt the shocks at the bottom, remove the trailing arms and unbolt the CV joints from the diff. I guess the brake lines would need to be dealt with too. Then move the complete trailing arm and wheel assemblies off somewhere else. Then drop subframe and diff together. Is that how you mean?

Re. bolts. Thanks but no. The 25mm OEM bolts aren’t quite long enough to convert into studs I think. I believe I can get 12MX1.5 wheel studs from the local autoparts store. Then I’m going to cut off the “press-in” part and use a die to clean up the threads.

Re. whining. That’s a strong word. I tried to come up with a mildly amusing response, but failed. I couldn’t come up with words that hinted at a fanatical opposition to whining, yet was free of arrogance and hubris. So I settled on redundancy (think about it).

#6

fyi: my offer for the bolts was to make up for being so “mean” to you.

couldn’t you just drill holes in the trunk to access the top bolts with socket and extension?

#7

[quote=“Ranger” post=55647]So you unbolt the shocks at the bottom, remove the trailing arms and unbolt the CV joints from the diff. I guess the brake lines would need to be dealt with too. Then move the complete trailing arm and wheel assemblies off somewhere else. Then drop subframe and diff together. Is that how you mean?
[/quote]
When I last dropped the subframe, I left the trailing arms (sans wheels) attached to the subframe. Disconnect driveshaft, brake lines, sway bar, shocks. Throw a trans jack under there and remove the subframe nuts and rear diff bolt. Wiggle as needed while lowering the jack.

Installation is the reverse of removal.

All in jest, my friend. But I still maintain that aluminum is overkill and only serves to make life harder.

I think you just found a name for my to-be-formed race team. Arrogance and Hubris Racing. Superior inferiority since 2005.

#8

[quote=“NASA144” post=55649]fyi: my offer for the bolts was to make up for being so “mean” to you.

couldn’t you just drill holes in the truck to access the top bolts with socket and extension?[/quote]

As I understand it, the beauty of putting studs in the two top bolts (not the 2 forward bolts) is that overcomes the problem of difficulty getting those bolts started. The other time I R/R’d my diff, getting those bolts started up there as I was holding up the diff and jiggling it around, was a complete bastard.

#9

I had the dif on my floor jack and got them started pretty easy by wiggling it around… guess I got lucky. :slight_smile:

I’m not so mean am I?

#10

[quote=“Steve D” post=55650][quote=“Ranger” post=55647]So you unbolt the shocks at the bottom, remove the trailing arms and unbolt the CV joints from the diff. I guess the brake lines would need to be dealt with too. Then move the complete trailing arm and wheel assemblies off somewhere else. Then drop subframe and diff together. Is that how you mean?
[/quote]
When I last dropped the subframe, I left the trailing arms (sans wheels) attached to the subframe. Disconnect driveshaft, brake lines, sway bar, shocks. Throw a trans jack under there and remove the subframe nuts and rear diff bolt. Wiggle as needed while lowering the jack.

Installation is the reverse of removal.
[/b][/quote]

This sounds like an interesting approach, but I’ve got the car up on the scissor lift and like the clutch job the scissor lift has it’s warts. I can’t get a jack under the subframe. In fact, it’s going to be a problem getting a jack under the diff to reinstall it. When I removed the diff last night I was laying on my back with my legs holding up the diff as I reached up and undid the last couple of bolts. For all the world I removed a differential while in a fetal position.

#11

I fixed the instructions for ya. :wink:

#12

[quote=“Steve D” post=55658][quote=“Steve D” post=55650]
When I last dropped the subframe, I left the trailing arms (sans wheels) attached to the subframe. Take car off scissor lift. Put car on 6 ton jack stands. Disconnect driveshaft, brake lines, sway bar, shocks. Throw a trans jack under there and remove the subframe nuts and rear diff bolt. Wiggle as needed while lowering the jack.

Installation is the reverse of removal.
[/quote]
I fixed the instructions for ya. ;)[/quote]

When the garage expansion is done, I could actually do this. Dang how I look forward to that. I could put the car’s wheels back on and drop it down. Then with a bit of work I could scoot the 900lb scissor lift out from under the front of the car until it was entirely clear. In the absence of the garage expansion tho, the car is on the lift until it can drive off.

Garage expansion report. Recall that I’m getting 9’ more garage. The pad was poured last week. Yesterday a bunch of drainage was put in to evacuate rain water that would have otherwise become a big problem. A “patio” that will extend 8’ beyond the garage expansion is supposed to be poured by the weekend. The garage expansion is getting it’s own “garage door”. This will allow me to roll things out of the expansion and on to the patio for more space. Like, say, a car.

#13

I like Steve’s method of removal. I envision doing this swap in the summer. Definitely jealous of Ranger’s new garage. Jackstands and driveway are the way I do all my work.

#14

All I got done tonight was separating the rear brake hydraulics and parking brake cable. I called Jim Levie to find out the logical way to attack the brake cable. Not a lot accomplished for 3hrs work.

I had hoped to get the subframe off w/o removing the exhaust, but that’s not going to fly. I thought maybe I could just remove the L trailing arm and then kinda scoot the subframe off to the R. But 15min spent trying to undo an outboard rtab bolt made it clear that the subframe needed to come off with trailing arms intact, and then meant that the exhaust was going to have to come off. Which is non trivial.

My exhaust is welded. Those clamps that came with the exhaust kit didn’t work all that well. So I’ll have to separate it at the downtubes. Then I’ll have to figure out how to put jack stands under the car, drop the scissor lift that is trapping the exhaust in place, and then get the exhaust out. I can see that taking all tomorrow night.

I was up pretty late last night, but tonight I knocked off before midnight.

#15

[quote=“Steve D” post=55650][quote=“Ranger” post=55647]So you unbolt the shocks at the bottom, remove the trailing arms and unbolt the CV joints from the diff. I guess the brake lines would need to be dealt with too. Then move the complete trailing arm and wheel assemblies off somewhere else. Then drop subframe and diff together. Is that how you mean?
[/quote]
When I last dropped the subframe, I left the trailing arms (sans wheels) attached to the subframe. Disconnect driveshaft, brake lines, sway bar, shocks. Throw a trans jack under there and remove the subframe nuts and rear diff bolt. Wiggle as needed while lowering the jack.

Installation is the reverse of removal.[/quote]
This!

#16

With the car on jack stands, just unbolt the downpipes from the exhaust manifolds using long extensions and a swivel joint. With an electric impact wrench, it should only take about five minutes. Then unhook the exhaust hangers at the back and wiggle the exhaust out the back of the car. Dont forget to unhook your O2 sensor. I’ve seen you change rocker arms in less than two hours. This exhaust issue should take you 15 minutes tops!!!

#17

Jim, as I do this I recall that the fasteners on your weld-on kit loosened up. The bolts on my eccentric rtabs aren’t all that tight, but the outer ones are hard enough to get to that getting them tight would be a problem. Ultimately I’m going to need to adjust them, but get them tight enough that they stay where I put them. How did you attack this? What comes to my mind is to put some locktite on them, and then get the alignment done before the locktite has a chance to set.

Is there a way to approximate the alignment of the rear wheels with the rear subframe, trailing arms and diff all out of the car? Like maybe if you put the wheels on support the subframe a certain way, like put it’s bushings on 8" of support, that will approximate the way the whole assembly sits in the car. That way you could probably adjust toe exactly and camber pretty close before installing the whole assembly.

#18

[quote=“Ranger” post=55679]Is there a way to approximate the alignment of the rear wheels with the rear subframe, trailing arms and diff all out of the car?[/quote]Yes, but it would require building a test rig with the suspension pickup points and weight distribution of a Spec E30. In other words, bolting it to a car…

#19

I think all it would take is knowing the height of the diff and the subframe, because their elevation “locates” the trailing arm pivot points. Heck, all the diff’s height does is make sure that the subframe isn’t twisted.

Can someone go measure this? On a relatively flat surface, measure subframe height as if the bolts and bushings were gone. Or maybe take a picture of your measuring points . That will ensure that folks that follow on measure subframe and diff heights exactly the way you did.

#20

[quote=“Ranger” post=55686]I think all it would take is knowing the height of the diff and the subframe, because their elevation “locates” the trailing arm pivot points. Heck, all the diff’s height does is make sure that the subframe isn’t twisted.

Can someone go measure this?[/quote]
PLEASE GOD MAKE IT STOP!!!

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