The Woj Posted January 26, 2011 Share Posted January 26, 2011 So I finally got around to installing my rear suspension and found that the bolts holding my diff up are interfering with my lower diff crossmember now. I was wondering if it is necessary to notch the lower diff mount as is illustrated here: And, if so, I was wondering how some people manage to sandwich the stock diff mount underneath and not notch the crossmember, as is illustrated here: For illustrative purposes, I have attached pictures of my setup and the trouble areas. Any help would be appreciated. Quote Link to comment Share on other sites More sharing options...
Neverdone Posted January 26, 2011 Share Posted January 26, 2011 (edited) So you can't attach your lower diff mount to act as a spacer? Edited January 26, 2011 by Neverdone Quote Link to comment Share on other sites More sharing options...
The Woj Posted January 26, 2011 Author Share Posted January 26, 2011 So you can't attach your lower diff mount to act as a spacer? Correct, I circled the first offending area where the bolt hit it in the 4th picture. There was still a good 1/4" left to tighten on the lower mount when it hit. Quote Link to comment Share on other sites More sharing options...
jasper Posted January 27, 2011 Share Posted January 27, 2011 In your pics, It appears you have the STOCK diff mount on TOP of the diff. It belongs in it's factory position, on the bottom of the diff. A bolt on snubber/bump stop (extra part) bolts on top. This is what it appears to be wrong from your pics. Quote Link to comment Share on other sites More sharing options...
The Woj Posted January 27, 2011 Author Share Posted January 27, 2011 (edited) In your pics, It appears you have the STOCK diff mount on TOP of the diff. It belongs in it's factory position, on the bottom of the diff. A bolt on snubber/bump stop (extra part) bolts on top. This is what it appears to be wrong from your pics. I have a GM 3201 tranny mount bolted to the top. I think you are referring to the stock configuration and not the RT config? Edited January 27, 2011 by The Woj Quote Link to comment Share on other sites More sharing options...
johnc Posted January 27, 2011 Share Posted January 27, 2011 So I finally got around to installing my rear suspension and found that the bolts holding my diff up are interfering with my lower diff crossmember now. I was wondering if it is necessary to notch the lower diff mount as is illustrated Yes. Quote Link to comment Share on other sites More sharing options...
The Woj Posted January 27, 2011 Author Share Posted January 27, 2011 (edited) Yes. Cool, thanks. Any idea how dsommer did it, as evidenced in the 2nd picture I posted stolen from this thread (56k beware!): http://forums.hybridz.org/index.php/topic/63391-resurection-now-becoming-1tufzg-z/page__view__findpost__p__809921 Also, what is the best way to cut it to retain structural integrity? Edited January 27, 2011 by The Woj Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 27, 2011 Share Posted January 27, 2011 (edited) Most people run the Energy Suspension 3-1108 - http://www.jegs.com/i/Energy+Suspension/355/3-1108G/10002/-1 Maybe it's not as tall as the GM 3201 that you say you're using. That would lift the nose of the diff up. I did a quick browse but can't find a 3201 on the internet to compare to the 3-1108. Edited January 27, 2011 by NewZed Quote Link to comment Share on other sites More sharing options...
The Woj Posted January 27, 2011 Author Share Posted January 27, 2011 Most people run the Energy Suspension 3-1108 - http://www.jegs.com/i/Energy+Suspension/355/3-1108G/10002/-1 Maybe it's not as tall as the GM 3201 that you say you're using. That would lift the nose of the diff up. I did a quick browse but can't find a 3201 on the internet to compare to the 3-1108. My bad, I was just going by the number stamped into the mount. I am pretty sure 3-1108 is what I bought, though all I can find in my records is a PayPal payment for 33.16 to ES (over a year ago), which sounds about right. Quote Link to comment Share on other sites More sharing options...
rossman Posted January 27, 2011 Share Posted January 27, 2011 I'd check to be sure your transmission and differential are lined up prior to cutting on the cross member. Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted January 27, 2011 Share Posted January 27, 2011 Rossman just touched on the key factor. Alignment. The position on the diff nose depends on the location of the tranny tailshaft. If you're running an L6 in the stock location than no notching is required (all else being equal). The nice thing about the RT mount is it's adjustability. In my set up I had to notch the crossmember much more that the pictures above. The idea is to get the u-joint angles as close to equal as posible to reduce driveshaft vibration. I wouldn't worry much about notching the crossmember. Once you take the bending loads from the diff mount off of it (by installing the RT mount), then you only have the tension/compression loads of the unibody/rear LCA's acting on it. My un-studied W.A.G. is that these are relatively small. MHO is that if you left a half inch tall vertical flange after notching you should be more than fine. Some guys have cut the middle of the crossmember out all together. Personally I wouldn't do that but I have no emperical evidence to say that is a bad idea. I just know that there are still tension and compression loads there so it tends to be a good idea to complete the box. Quote Link to comment Share on other sites More sharing options...
sweetride2go Posted January 27, 2011 Share Posted January 27, 2011 I didn't have to notch mine, but I also didn't run that steel spacer they give you with the poly mount, and I ground some poly off to get the mount to sit nice on the nose of the diff. Polyurethane grinds much better than I thought it would, haha.... Cheers Ryan Quote Link to comment Share on other sites More sharing options...
The Woj Posted January 27, 2011 Author Share Posted January 27, 2011 I think I'll grind the crossmember, I still have a decent amount of work left to do on the car before mocking engine/tranny fitment and I want to be able to put wheels on it to roll around. If it really becomes an issue, I'm sure I can find a used crossmember on the cheap. Quote Link to comment Share on other sites More sharing options...
The Woj Posted January 28, 2011 Author Share Posted January 28, 2011 So here's the carnage. I may have gotten a bit over-zealous, but I think I left enough metal to ensure integrity. I misinterpreted my markings on the piece and accidentally cut the wrong area on the passenger side, so that's why so much is missing on that side. Quote Link to comment Share on other sites More sharing options...
Oddmanout84 Posted January 28, 2011 Share Posted January 28, 2011 I'd still weld some metal back into the voids just to gain back a little strength. Quote Link to comment Share on other sites More sharing options...
The Woj Posted January 28, 2011 Author Share Posted January 28, 2011 You're talking concave pieces of metal to fill the holes in the opposite direction? Quote Link to comment Share on other sites More sharing options...
Oddmanout84 Posted January 28, 2011 Share Posted January 28, 2011 You're talking concave pieces of metal to fill the holes in the opposite direction? Yes, exactly. Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted January 28, 2011 Share Posted January 28, 2011 Woj it looks great. Drive it around for a while. The nose of the diff moves about some between shifts and transitions from brake to power to brake. You may find you need a little more clearance. Put a little paint on the bolts and crossmember where they are close and see if any gets knocked off. Quote Link to comment Share on other sites More sharing options...
dsommer Posted January 28, 2011 Share Posted January 28, 2011 (edited) I used the stock lower mount then used a ES tranny mount for a Chevy transmission. We had to trim the BOTTOM part of the ES mount in a curved shape to conform to the top of the dif. Then it is sandwiched between the RT mount and the top of the dif. Trimming the ES mount was a pain in the a$$, I botched one and had to buy another. Sorry to chime in after the fact.... Edited January 28, 2011 by dsommer Quote Link to comment Share on other sites More sharing options...
The Woj Posted January 29, 2011 Author Share Posted January 29, 2011 Woj it looks great. Drive it around for a while. The nose of the diff moves about some between shifts and transitions from brake to power to brake. You may find you need a little more clearance. Put a little paint on the bolts and crossmember where they are close and see if any gets knocked off. I don't think I am going to need to do that. I bolted everything in, did some inspecting and found that the snout of the diff is actually resting on the crossmember now. I think I am going to need to grind material off the mount so the diff fits in it better and lose the 2 washers. I still have no idea how you got that to fit dsommer, perhaps your RT mount is higher than mine? The stock mount is something like 3/4" tall, I don't think I could remove that much material from my mount. Here is a picture to illustrate my problem: Quote Link to comment Share on other sites More sharing options...
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