bjr

Why does it seem like all of the discussions on the two major diff braces fell off in the last year or two? I think I may benefit from one but am not convinced either one is prefect by any means and don't see any recent talk or support of either one. They do seem like they are both still available to order from their manf. website but no recent talk about them. Have people decided they are not a great idea? I would like some advice before I spend $150-$250 on something that may not be needed in my case.
Over 2 years ago and about 57,000 miles ago I bought a junkyard pumpkin, 4.083 gears and a Quaife and put it all in with solid diff bushings. My rear factory bushing was cracked a little and was lucky of the timing of doing this project since I had no idea it was damaged.
Today I figured out I have a sheared off rear stud. I don't even know what made me check it because I don't think there are any new symptoms. I must have heard something to check but am not sure what it was yet. For all I know it could have happened 50,000 miles ago.
I do have a couple of questions as I try to figure out what I'm going to do with it.
1) I see the stud is available for less than $3. As long as the cover is not cracked I just replace the stud? Who has actually cracked a cover? I have my original cover to use also if I run into problems but it had 180,000 very hard miles on it.
2) I could not find any other damage. Is there anything you can think of that could cause the stud to fail or that may be now damaged from driving with the stud broken?
3) I know hard launching and rough driving could have caused this but what exactly causes this? I want to understand the physics before I decide to buy a brace. The two front mounts still seem to hold it tight. I know the driveshaft tries to twist the pumpkin off the car but which motion actually shears the stud. Is it left to right or up and down? I am having a hard time with this since the front ears don't seem to allow it to move. How does it even break with everything solid. I guess I am too frustrated to imagine it!

I know, hard to do over the internet but I am not a total noob. I just need to talk about major things before I do them. I feel like I need some good advice!

bjr

On the way to work this morning it seems painfully obvious that it broke yesterday. I was less that a mile from home. Pulled out from a side street to cross a busy 4 lane. The side street is slightly downhill so if you can imagine, when you reach the main road and it levels out, there is a dip. I typically take off hard but don't do anything highly abusive. I always bring up the clutch and start to give a little gas so it doesn't stall. Then after I am rolling and the drive line slack is up I will quickly press the pedal to the floor but never slam it. Well as I hit WOT through the dip I thought I heard a small crunch and probably thought the wheel snapped down into the rut. But maybe that was not a suspension noise but the stud shearing?
I now have a clunk in between shifting gears that could not have been there before so I guess I broke it or finished it off yesterday.
One thing I am remembering from inspection is that the case does not fully touch the subframe or solid bushing. That could be as much as 1/16" gap. When I remount this, I should probably leave the front mounts a little loose and see if tightening the new stud draws the case to the frame or not. What should the goal be on this? (Diff touching the frame or not)????

jdm-v35

iTrader: (7)

if you have solid bushings, it will probably not pull the case to the frame. you will need to hammer the rear bushing in a littler further till its flush with the case. if there is indeed a gap thats probably how you broke the stud. having the case flush with the solid bushing takes the load of the stud and just uses the stud to mainly keep it in place. its the same concept as having a wheel not being flush with the hub. increases stress on the studs causing them to shear off. if you're n/a power levels you should not have issues. SP made the diff brace because they sheared a stud during a hard launch with like 800+hp. at stock power levels you shouldn't have any issues with oem stud and solid bushings.

just buy the stud, make sure everything sits very flush, and properly torque it and you should be good.

bjr

I probably won't know for sure until I can start to take it out but I hope that is what happened. Otherwise I'll have to drive like a grandma the rest of my life. Thanks for the sane advice on the brace.

bjr

In not sure if I should be driving it? It seems OK but I'm not sure how much it would take to damage the front two bolts. The drive line has always had a small clunk to it. I can crawl under it and twist the drive shaft back and forth and hear that old noise in the u joint or gear slop a bit too but there is definitely a new clunk/rattle when shifting which should be the diff moving some now. I can baby it and slip the clutch and not get a clunk most of the time but I am afraid of what I might be doing to it.

bjr

After dinner I decided not to risk it and figured out a different schedule to get to work with my wife home this week.
Just need to drop the diff now, everything is loose but the OEM sway bar. I wish I could remember if I have to take it off or at least drop it out of the way to get the diff out. The bolts are soaking in pb blaster for the night.
Good news so far is the drain plug didn't have anything stuck on it to worry about and even though there is a little weeping from the passenger side seal I drained out the proper amount of fluid. Hopefully my stud and seal come in and my new amsoil. Wish me luck...

bjr

Not going good!
I took out the diff and repaired it. I see where my subframe bushing has a lead in taper to clear the shoulder on the stud and allow the diff cover to sit flush. I had the diff back on the car once and could leave the front two bolts a little loose. Then I could shove the case towards the back of the car and get the cover to sit flush to the bushing and then shove it to the front of the car and had a 0.054" gap. The bushing sat 0.040" inside the frame so I used a slide hammer and pulled it 0.014" outside the frame. I put the diff in and can no longer get the case to sit flush. And it seems at a slight angle because at the top of the case it is only 0.001" gap and at the bottom 0.010".
It shouldn't be this touchy I don't think. I have no idea if the subframe is straight, or if the driveline angle was ever right with the front bushings the dimensions they are. If I cannot get it to come out and go back in straight I don't know what to do.
I've left it a little loose and tried moving it around with the help of my jack and can't get it to sit where it needs to again. It is true that you cannot tighten the subframe nut and try to draw it in. Hopefully I'm just too tired and I can start over tomorrow and measure everything again and get it flush and tighten it right then and hope when I finish tightening the front ones it doesn't bind anything and put lots of stress on the stud in an up or down direction. I am also worried that the first time I missed a small gap and it wasn't flush like I thought and will never get it to fit flush at all.
I'm not sure what else I have to check or do to get this right!

jdm-v35

iTrader: (7)

only other thing is you could have put the front diff ear bushings in upside-down. they have different heights which would cause the rear to sit uneven.

bjr

All of my front bushings are the same size. I think they are from torque solutions. I plan on measuring my other diff tonight to see if there is any difference. I hope that is not it actually. I guess I could put a fender washer or some of the OEM pads or washers in if the stack up is too short. I should try to contact torque solutions today and see if I did something wrong.
If the drive angle was off that much wouldn't the rear end be ruined after 57,000 miles and show some signs?

jdm-v35

iTrader: (7)

No It would only shear the bolts off until the rear end drops out, THEN it would trash everything, as the driveshaft end and axles are joints and not solid axle being a small amount off will not affect it like that.

bjr

If I cannot get the case to sit flush again do you feel like the Injected Performance brace and less abusive driving would prevent this from happening again? I'm worried I may need some kind of compromise to get my car back on the road...

jdm-v35

iTrader: (7)

if the diff does not sit flush the brace will just be a bandaid imo. Though it may work, if the angle is off in back, the front bolts are likely going to be slightly angled and would cause issue later on as the diff brace only supports the rear.

dunno about all the solid bushing sets but if you look here these are slightly different sizes. If you have ones like that and put it on the wrong way it will cause the issue you have.

Also saw a pic of torque solutions bushings on google and they seem to be different heights like the picture shown.

bjr

I'll try to keep this brief since there are some unknowns and I didn't get it the way it should be. I have to admit that when I put solid bushings in over two years ago I was probably so focused on cutting out the old bushing and so worried that my new diff was setup properly (I did it myself) that I never even considered that the case did not sit flush against the bushing. Didn't think about it or even notice it probably did not fit right.
Anyway, I was down to my last night of having another car to drive to work so this had to be finished. I started by lowering the diff out of the frame a few inches, squaring it up on the jack and trying one more time. I held the case flush and hand tightened the subframe nut. I then was excited to see that the two front bolts looked right on for lining up and could start both bolts by hand. The previous night I had a difficult time getting anything to line up and repositioned it three times before I went to bed with my head hung low.
Half way through tightening the front bolts I torqued the subframe bolt down all the way. With the last 1/2-3/4" left to go on the front ones, as I tightened them somehow the case started separating itself from the rear bushing again to my frustration. At this point I had to decide to keep going. I stared at it for another 15 minutes questioning what would help and knew I would be out there until midnight again and be at the same point with no driveable car. I had already pulled the bushing forward with a slide hammer the day before over 0.070" forward with the gap looking no different now than before I ever took it out of the car and the stud was still broken! It seems like the logical thing is to move the bushing forward but my moving it some already made no measurable difference in the end. Something else is also going on. I'm sure that if I had several hours, a proper two post lift, and a friend or mechanic to help with ideas and leverage I'd get it but it is way beyond me on a Friday night with a deadline.

After driving it for two days I also have a new impression of what may have happened. It is so quiet now (no rattles over bumps the last few feet before stopping in neutral. In the last several months I thought I heard a small crunching noise from my left rear shock pulling out of the driveway or the right kind of bump in a parking lot that I thought it was an aftermarket poly bushing rubbing - gone now from what I can tell). I think a very long time ago the subframe nut just loosened up and eventually fell off. I wish I could go back and find the bolt on the road to prove this. Because it explains a lot of things rather than just the last day when it sheared off.
So after coming home from work Saturday I figured out I had just enough stud left to get a second nut jammed onto the first nut with some red Loctite and hope that prevents the nut from coming loose because that gap will allow some flex and loosening. Don't know what else to say other than it's not right and I don't know why.
Oh yeah, Torque Solutions hasn't called me back. And I noticed in the big write up jake did on replacing the rear bushing with a C-clamp that the SPL solid kit also has all four ear bushings the same size. So at this point I didn't have enough time to get to the bottom of this and hope it holds up for awhile.

This has turned out to be a pretty useless thread but I greatly appreciate all of the advice. And since I am pretty detailed oriented and missed this fine point I hope it is an important warning to some other owner considering putting in different bushings.

My final point that remains a question in my mind now. How can you take a solid case and put two bolts in it up front and then bolt the rear to the subframe which can move? How much can the subframe flex since it is on rubber bushings? I know the OEM bushings flex for NVH but aren't they also necessary to move the diff with the subframe?

Also I finally understand the complaints about the single stud being a pathetic design. I was looking into some stuff last week and came across a Honda S2000 site and that diff has FOUR rear studs off the back cover and two huge trailing arms off the front to tie it to the main frame! Unbelievable difference...

jdm-v35

iTrader: (7)

thanks for keeping us updated on this. I personally decided to get ES urethane bushings which I have not put in yet as I am debating whether to replace my 3.3 with a 3.5 FD pumpkin. The design is definitely not the strongest, but under OEM power range there really should be no issues. I guess if the bushings no longer give, then something else needs to. in this case, the stud.