Problem fitting DRM rear trailing arm brackets
Thread Starter
Drifting
Joined: May 2002
Posts: 1,581
Likes: 2
From: The Motor City
Problem fitting DRM rear trailing arm brackets
Hi all,
I ordered up a set of rear trailing arm brackets from DRM a couple of years back, and I'm only now getting around to installing them. Unfortunately, it seems the stand-off pieces that mate to the chassis are welded too close together (by a small amount), making it virtually impossible to get the brackets to sit flat against the mounting surfaces.
I'm just curious if anyone else with DRM trailing arm brackets has encountered the same issue, or if I'm the lucky winner of an incorrectly made set of brackets?
I ordered up a set of rear trailing arm brackets from DRM a couple of years back, and I'm only now getting around to installing them. Unfortunately, it seems the stand-off pieces that mate to the chassis are welded too close together (by a small amount), making it virtually impossible to get the brackets to sit flat against the mounting surfaces.
I'm just curious if anyone else with DRM trailing arm brackets has encountered the same issue, or if I'm the lucky winner of an incorrectly made set of brackets?
Drifting
Joined: Nov 1999
Posts: 1,324
Likes: 18
From: St. Peters MO
I don't recall any issues when I have installed them in the past? I do know that polyurethane bushings on the dogbones are a tight squeeze to get into the bracket!
Try a "rat-tail" file on the bolt holes, enlarging just enough to get bolts to line up with the threads. Do only the top OR bottom hole first, then do the other hole only if needed. Only remove as much material as necessary.
Try a "rat-tail" file on the bolt holes, enlarging just enough to get bolts to line up with the threads. Do only the top OR bottom hole first, then do the other hole only if needed. Only remove as much material as necessary.
Thread Starter
Drifting
Joined: May 2002
Posts: 1,581
Likes: 2
From: The Motor City
Thanks for the feedback and suggestion.
But I think my description of the problem wasn't very clear. The holes line up just fine. It's the two stand offs on the back of the bracket that rest within the two 'pockets' which are stamped in the chassis which are causing the problem. It appears they've been welded too close together, making it impossible for the brackets to sit flat against the mounting surfaces (where the bolts are).
If nobody else has experienced this issue then I may have to resort to modifying these brackets to make them fit. Which is a shame for two reasons: 1. they are brand new, and I hate hacking-up new parts (which should have been made correctly in the first place), and 2. they have already been powder coated, so modifying them will mean a second trip to the powder coater before installation.
But I think my description of the problem wasn't very clear. The holes line up just fine. It's the two stand offs on the back of the bracket that rest within the two 'pockets' which are stamped in the chassis which are causing the problem. It appears they've been welded too close together, making it impossible for the brackets to sit flat against the mounting surfaces (where the bolts are).
If nobody else has experienced this issue then I may have to resort to modifying these brackets to make them fit. Which is a shame for two reasons: 1. they are brand new, and I hate hacking-up new parts (which should have been made correctly in the first place), and 2. they have already been powder coated, so modifying them will mean a second trip to the powder coater before installation.
Former Vendor
Joined: Feb 2004
Posts: 9,615
Likes: 13
From: Burlington NC
Please send me a picture or some measurements so I can maybe help correct the issue. Is it off by 1/4 inch, 1/2 inch or ????
Randy
drm@dougrippie.com
Randy
drm@dougrippie.com
Thread Starter
Drifting
Joined: May 2002
Posts: 1,581
Likes: 2
From: The Motor City
Hi Randy. I'll try and post a picture in the next little while, if not tomorrow morning some time.
I think if the spacing between the two stand-offs were increased by at least a 1/4" it would alleviate the issue. In fact, I compared the two DRM brackets I have, and one has more space between the the stand-offs, so the second bracket may fit ok... but I haven't tried that one yet.
I also have my original brackets, so I can try to take a picture of those as well for comparison.
I think if the spacing between the two stand-offs were increased by at least a 1/4" it would alleviate the issue. In fact, I compared the two DRM brackets I have, and one has more space between the the stand-offs, so the second bracket may fit ok... but I haven't tried that one yet.
I also have my original brackets, so I can try to take a picture of those as well for comparison.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Thread Starter
Drifting
Joined: May 2002
Posts: 1,581
Likes: 2
From: The Motor City
Hi all. Sorry about the delay in getting a photo, but here's what I'm talking about. Forgive the poor picture quality.
As can be seen in the photo, the OEM bracket's stand-offs are 2.5" inches apart (taken tangent-to-tangent, since the radii in that area are so large). The DRM bracket's stand-offs are 2.0" inches apart (taken corner to corner, since there are no radii). This difference is preventing the bracket from sitting properly against the chassis; the bolt holes line up, just fine.
So am I the only person who's had this issue, or am I doing something wrong during the install...?
[IMG]
[/IMG]
As can be seen in the photo, the OEM bracket's stand-offs are 2.5" inches apart (taken tangent-to-tangent, since the radii in that area are so large). The DRM bracket's stand-offs are 2.0" inches apart (taken corner to corner, since there are no radii). This difference is preventing the bracket from sitting properly against the chassis; the bolt holes line up, just fine.
So am I the only person who's had this issue, or am I doing something wrong during the install...?
[IMG]
[/IMG]
Drifting
Joined: Jun 2001
Posts: 1,704
Likes: 459
From: Mass Mass
I bought these brackets around the same time you did.
My Vette has spent the last few years in Body Work limbo, so I haven't installed them either.
Best help I can give is a picture of mine.
Can't tell you if they fit or not, but I would like to know also.
My Vette has spent the last few years in Body Work limbo, so I haven't installed them either.
Best help I can give is a picture of mine.
Can't tell you if they fit or not, but I would like to know also.
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Thread Starter
Drifting
Joined: May 2002
Posts: 1,581
Likes: 2
From: The Motor City
SuperL98, judging by the distance between the stand offs, I think you'll probably encounter the same issue when you do eventually go to fit your DRM brackets too. Of course, the only way to know for sure is to test-fit them to see if they sit flat against the chassis mating surfaces.
Strange that nobody else has reported this problem. I wonder if people are either modifying their brackets to fit or if they're just installing them as-is...?
Strange that nobody else has reported this problem. I wonder if people are either modifying their brackets to fit or if they're just installing them as-is...?
Last edited by TheCorvetteKid; Jun 16, 2013 at 07:54 PM.
Former Vendor
Joined: Feb 2004
Posts: 9,615
Likes: 13
From: Burlington NC
Here is where we are at.
Checked print (dated back to 1998), your parts are good
Checked inventory, good
Checked fit on our half chassis. One side is perfect the other side was a tick tight. After bolts were tight they fit flat.
Thinking out loud here. I don't think every car is the same. Even one side to the other, or year to year. The reason why this hasn't been a issue is because after the bolts are torqued down that tin moves enough to never be a issue.
Randy
Checked print (dated back to 1998), your parts are good
Checked inventory, good
Checked fit on our half chassis. One side is perfect the other side was a tick tight. After bolts were tight they fit flat.
Thinking out loud here. I don't think every car is the same. Even one side to the other, or year to year. The reason why this hasn't been a issue is because after the bolts are torqued down that tin moves enough to never be a issue.
Randy
Drifting
Joined: Jun 2001
Posts: 1,704
Likes: 459
From: Mass Mass
Randy, my car happens to be up on the rack anyway, so I took a minute to try these out.
I have the same interference as CorvetteKid.
Quite a mismatch and sizable gap between the plate and the frame.
I tried to tighten the bolts (normally) and the gap didn't close up, but I may try again.
I think the reason nobody saw this before is the wheel splash pan is in the way, I unscrewed and pulled mine back.
Do we even need these locator pads?
Looks like they are for strength on the sheet metal parts, but I don't think these heavy metal brackets need them?
I might just mill the inside welds off so it sits flat.
Hard to get pictures, did the best I could.
I have the same interference as CorvetteKid.
Quite a mismatch and sizable gap between the plate and the frame.
I tried to tighten the bolts (normally) and the gap didn't close up, but I may try again.
I think the reason nobody saw this before is the wheel splash pan is in the way, I unscrewed and pulled mine back.
Do we even need these locator pads?
Looks like they are for strength on the sheet metal parts, but I don't think these heavy metal brackets need them?
I might just mill the inside welds off so it sits flat.
Hard to get pictures, did the best I could.
Team Owner
Joined: Sep 2003
Posts: 25,373
Likes: 2,734
"SuperL98" - yours is prime for the "question" and it appears that the DRM pieces were engineered to use the center rise in the chassis to locate it. DRM's half chassis has of course had many bolted to it so it's been "accommodated" I guess you could say.
Bolt yours to the chassis using the recommended torque and see if what Randy mentions is indeed correct. I'm guessing that it will be and you could move along. You don't want to consider removing them, maybe a small chamfer wouldn't hurt and I don't see where it would destroy the powder coat that someone had mentioned. It might require a "brush touch-up" but I wouldn't think something that would need addressed.
Bolt yours to the chassis using the recommended torque and see if what Randy mentions is indeed correct. I'm guessing that it will be and you could move along. You don't want to consider removing them, maybe a small chamfer wouldn't hurt and I don't see where it would destroy the powder coat that someone had mentioned. It might require a "brush touch-up" but I wouldn't think something that would need addressed.
Drifting
Joined: Jun 2001
Posts: 1,704
Likes: 459
From: Mass Mass
I went back out and tightened the living &*$%# out of the bolts with a breaker bar.
The bracket ends came down to the chassis but I could still pass a .020 feeler gauge under the bracket at the middle bolt.
I had to mill about 90% of the welds flush to get the center to have no gap when tightened.
I have welders and may mill out those blind holes (to clean out the powder coat) and plug weld the spacers in the holes.
I'm happy, I've had to do a lot worse on aftermarket parts.
Another odd and interesting thing is the bolt mounting holes are not centered in the stock bracket, like you would expect, but offset quite a bit to one side?
The bracket ends came down to the chassis but I could still pass a .020 feeler gauge under the bracket at the middle bolt.
I had to mill about 90% of the welds flush to get the center to have no gap when tightened.
I have welders and may mill out those blind holes (to clean out the powder coat) and plug weld the spacers in the holes.
I'm happy, I've had to do a lot worse on aftermarket parts.
Another odd and interesting thing is the bolt mounting holes are not centered in the stock bracket, like you would expect, but offset quite a bit to one side?
Drifting
Joined: Jun 2001
Posts: 1,704
Likes: 459
From: Mass Mass
Team Owner
Joined: Sep 2003
Posts: 25,373
Likes: 2,734
I went back out and tightened the living &*$%# out of the bolts with a breaker bar.
The bracket ends came down to the chassis but I could still pass a .020 feeler gauge under the bracket at the middle bolt.
I had to mill about 90% of the welds flush to get the center to have no gap when tightened.
I have welders and may mill out those blind holes (to clean out the powder coat) and plug weld the spacers in the holes.
I'm happy, I've had to do a lot worse on aftermarket parts.
Another odd and interesting thing is the bolt mounting holes are not centered in the stock bracket, like you would expect, but offset quite a bit to one side?
The bracket ends came down to the chassis but I could still pass a .020 feeler gauge under the bracket at the middle bolt.
I had to mill about 90% of the welds flush to get the center to have no gap when tightened.
I have welders and may mill out those blind holes (to clean out the powder coat) and plug weld the spacers in the holes.
I'm happy, I've had to do a lot worse on aftermarket parts.
Another odd and interesting thing is the bolt mounting holes are not centered in the stock bracket, like you would expect, but offset quite a bit to one side?
I have a pair of OEM here attached to suspension components and not easily accessed but reaching with a string I'd have to say mine are "vertically" on the same line as one would suspect. Way to much trouble to pull out from where they are in storage. It was a tough stretch just to reach! I see looking at ypu image again you're meaning the holes aren't on center to the bracket edges? Is that correct?
Last edited by WVZR-1; Jun 18, 2013 at 06:22 PM.
Team Owner
Joined: Sep 2003
Posts: 25,373
Likes: 2,734
Hey Randy,
The rods are the same all years but the brackets were part numbered differently through '87. One number didn't supersede the other, the older was just discontinued. It might be interesting to compare some "known" early ones to the later '88+ ones.
The rods are the same all years but the brackets were part numbered differently through '87. One number didn't supersede the other, the older was just discontinued. It might be interesting to compare some "known" early ones to the later '88+ ones.
Thread Starter
Drifting
Joined: May 2002
Posts: 1,581
Likes: 2
From: The Motor City
I didn't even notice the off-center bolt holes on the OEM brackets but SuperL98 is correct; the OEM brackets from my car have off-center mounting holes. I also don't know if anyone else has noticed, but the OEM brackets are marked "OUTBOARD" on one side. My guess is the OEM brackets are located to avoid any binding in the trailing arms.
I was thinking about modifying my DRM trailing arm brackets in the same manner as SuperL98 has (milling off about a 1/4" from each stand-off). fortunately, the DRM brackets I have don't have anywhere near as much weld as SuperL98's pieces so the job won't be too difficult. But the off-center bolt holes on the OEM brackets have me a bit concerned that the trailing arms may encounter some binding once reinstalled using the DRM trailing arm brackets.
Funny that nobody else has noticed this before, especially considering these brackets have been available from DRM for years.
Last edited by TheCorvetteKid; Jun 23, 2013 at 07:44 PM.