Differentail front bolts not lining up

[PersonalFoul]

Hey all

Before i call FFR support thought that I might see if you smart people have any insights to this issue. Just got my car two weeks ago and started to put the IRS differential in that i got from FFR into the frame.

I cant get the front two bolt flanges in the diff to align to place the M16 bolts into the bushing with the metal sleeves inserted. I can get the rear bolts into the threads but the front not even close

The two side dont even line up very well on the miss on the frame, one one just a hair off and the one the left might be almost an 1/8" low and the right.

Anyone have any ideas on what i might be doing wrong or fixes that i can try. I tried using straps to pull it over, using a prybar, using a hammer and the long way on a 2x4 to apply some force but I think that this should not be this hard

Thanks for the help in advance and happy holidays all!

Cheers

Mike

[edwardb]

In my experience doing a couple of them, you'll have a hard time getting it to move much applying external force. Been there done that. This is a write-up I did in my #8674 build. Worked for me and did the same on my Coupe build.

Once the center section is finally in the right position over the frame rail, it takes some serious persuasion to get it lined up. Due to the angles of the mountings, I found it necessary to get above the attachment points, and push it down from above. First align the rear bolts since they're threaded into the rear cover. Once they're started in, leave them loose and go to the front bolts. Here's where I hit the wall. Because it's so tight, it's nearly impossible to move a little at a time. Plus it seemed a little off center. I was using a 2x4 and a dead blow hammer, and then moved up to a small 4-lb sledge. Thought about the next sized sledge I could get my hands on, but time to stop beating on this thing. A 5/8 inch bolt goes through the two center section front mounts, and into bushed sleeves in the chassis. The alignment has to be perfect or the bolts either won't go in or just start pushing the sleeves out. After a while and increased frustration, I decided it was time to stop and think about this. Sometimes that's the best option.

Several things occurred to me. First, all the tolerances are really tight. One of the preparation steps for the center section is to "chase" (as the instructions say) the front mounts with a 5/8 inch drill. The existing hole is probably about 1/2 inch diameter. I bought a brand new 5/8 inch bit to also drill out one of the holes in the knuckles, so used it here as well. It was quite challenging because it really wanted to grab. A step drill would be a much better choice, but I didn't have one that would work. But if I had to do it over, I might drill the holes slightly oversize. But impossible to do once it's in the chassis. Next I decided something tapered to drive into the holes and line them up would be ideal. Something like ironworkers use called a bull pin. Even better would be two. I found what I was looking for on-line at a local tool store, but it was way too long to fit into the available space and I wasn't going to buy a new tool and cut it up. Then it occurred to me to modify the temporary 5/8 inch bolts I picked up at our local Ace (the real bolts are on my backorder list) and make my own alignment pins. So after sleeping on it, spun the two bolts I had on my disk sander, making a nice long taper and pretty much removing all the threads. Looked like this when done:

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3351_zpsrfmo05qr.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Independent%20Rear%20Suspension/IMG_3351_zpsrfmo05qr.jpg.html)

I put some assembly lube on them, and guess what? Relatively light taps from side to side and both went all the way home with the center section all lined up. Pulled the pin back out one at a time and the sleeves and bolts slid into place. Then tighten all to the specs in the instructions.

[PersonalFoul]

Ebwardb - thanks so much for the post, I have read every page of both your Roadster build logs and have over 10 pages of notes and links to your pages. I have tried to take a couple of pictures into the bushing showing the alignment. Not sure of how the forums will upload the pics but the one that is clearly off is the drivers side and the other that is a little blurry is on the passenger side and it almost lines up. The drivers side is way off? I have drilled the holes to 5/8", used brother in laws big *** shop drill press, so I think its ok?

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[JohnK]

I used Edwardb's build thread guidance when installing my IRS, and it went in relatively easily. I don't have much to add other than a couple of small tips. You said you were able to get the two rear bolts into the threads. I would back those out until only a few threads are engaged. I would also push the metal sleeves that are in the rear bushings out backwards so that they're against the heads of the rear bolts. The sleeves will get drawn into the bushing later when you tighten the rear bolts, but having the bolts backed out and the metal sleeves pushed out will give you a lot more wiggle movement in the IRS as you try to get the front bolts started. Good luck! You'll get it.

[FF33rod]

What Paul (EdwardB) and JohnK said, the same issue exists with putting the IRS into the '33. Engaging the rear bolts only slightly, backing out the metal sleeve, and using a spike were key to getting it into place.

Good luck!

Steve

[edwardb]

Ebwardb - thanks so much for the post, I have read every page of both your Roadster build logs and have over 10 pages of notes and links to your pages. I have tried to take a couple of pictures into the bushing showing the alignment. Not sure of how the forums will upload the pics but the one that is clearly off is the drivers side and the other that is a little blurry is on the passenger side and it almost lines up. The drivers side is way off? I have drilled the holes to 5/8", used brother in laws big *** shop drill press, so I think its ok?

You're welcome. Happy to see those build threads keep on being helpful. Yours is off about as much as the ones I've done. As I said, and others reinforced, get the rear bolts just started a few turns in. You'll be surprised how much it moves and how relatively easy it is to line up the front mounts with the tapered pins. Lots have been installed other ways. So the pins aren't the only method. But has worked for me and others.

[Hoooper]

Mine was similarly a fight to get in. I was able to get it in by loosening all of the bolts so they were just in by a couple threads and using a jack on the opposite side of the diff to rotate the drivers side bolt down from what I remember.