Author Topic: New subframe bushings and fender alignment problem  (Read 15886 times)

dmleonard

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New subframe bushings and fender alignment problem
« on: June 12, 2008, 01:37:40 AM »
I finally got to a point where I could put the subframe back under the car.  I installed it with new bushings and now the fender gap is way off.  It is tight against the door on the top and about an inch wide at the bottom.   I don't remember any fender alignment issues with the car when I bought it, but truth be told, I didn't pay much attention, threw out the old bushings, and it has been about 3 years.  I've tried every possible combination of the bushings with no success.  The only way I can even get it close it to add about 1/2" of spacers to the front subframe mounts in order to bring the radiator support down far enough to even get it close.  Has anyone experienced anything like this?  I bought the kit from DR Classic, but it did not come with instructions and there are no p/n's on them to try a reference against the assembly manual.
I am really starting to wonder if I got the wrong kit and am about ready to pull my hair out.  TIA for any help

pbranen

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Re: New subframe bushings and fender alignment problem
« Reply #1 on: June 12, 2008, 02:57:49 PM »
Did you take the frame out from under the car?  This is what I would do if I were you....

1st  Put the car up on stands.  Make sure your level from front to back by putting a level on the rocker panels.  Then make sure the car is level from side to side by putting your level on the flatest part of the dash.

2nd  There are alignment holes in the middle of the sub frame and at the front body mount by the firewall.  Stick a dowl rod through both holes and make sure it's plum.  Lock down your body bushings.  This is the best way to get the subframe as close as possible

3rd  Realign all front end sheet starting from the door jamb forward.

This is how I did mine after I had the frame powder coated and all new front end sheet metal.  It worked well and have almost identical panel gaps all the way around.  It took a long time and a lot of beer with my buddy.  Came out the next morning to verify that we werren't too drunk and it was good to go.  LoL
1968 Camaro Standard Coupe
327
2 speed power glide

Mark

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Re: New subframe bushings and fender alignment problem
« Reply #2 on: June 12, 2008, 04:24:23 PM »
The 2 front bushings are different than the 4 under the car, make sure you didn't mix them up.
Mark C.
1969 Indy Pace Car
350/300HP RPO Z11

dmleonard

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Re: New subframe bushings and fender alignment problem
« Reply #3 on: June 12, 2008, 05:10:21 PM »
Thanks for the advice.  I did not level the car before putting the subframe in, so I'll give that a try.  There are 6 bushings - I have tried all combinations, but I have them in now this way:  The two small diameter bushings under the radiator core support. Of the 4 larger diameter bushings, I have the thick ones in the front/firewall mounts and the thin ones in the rear mounts.

pbranen

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Re: New subframe bushings and fender alignment problem
« Reply #4 on: June 12, 2008, 05:32:18 PM »
Can't remember what the diameter of the alignment holes are.  Measure it and buy a woodedn dowl
1968 Camaro Standard Coupe
327
2 speed power glide

pbranen

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Re: New subframe bushings and fender alignment problem
« Reply #5 on: June 12, 2008, 05:33:14 PM »
sounds like you have the bushings in right
1968 Camaro Standard Coupe
327
2 speed power glide

RamAirDave

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Re: New subframe bushings and fender alignment problem
« Reply #6 on: June 13, 2008, 04:37:26 AM »
The smallest diameter bushings go in the rear of the subframe.

I think the large diameter/low profile bushings go in the rad support.
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Mark

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Re: New subframe bushings and fender alignment problem
« Reply #7 on: June 13, 2008, 10:54:44 AM »
The smallest diameter bushing goes under the radiator support, of the two larger diameter bushings the thicker pair go under the firewall support and the thinner pair go under the rear support.

I've got polyurethane bushings so I can't tell if the original bushings under the radiator support are different thicknesses, but if they are, the thin one should be between the frame and the core support, that will lower the front end, and close the gap at the bottom of the doors.
Mark C.
1969 Indy Pace Car
350/300HP RPO Z11

dmleonard

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Re: New subframe bushings and fender alignment problem
« Reply #8 on: June 13, 2008, 04:31:21 PM »
I really appreciate all the help - thanks very much.  I am in the process of leveling everything right now.  I have the car leveled and the subframe loose.  I am going to run and get a dowel this afternoon to make sure it is plumb.  The kit came with 6 bushings.  2 of the larger diameter bushings were thin and two were thick.  The smaller diameter ones that go with the rad support (I am assuming) are the same thickness as the thin set from the larger diameter.  I have the large diameter thin ones in the back of the subframe, the thick ones in the front, and the small diameter thins in the core support.   I will post the results after I level everything.

To give some background as I have been working on this for months now:
I was pretty sure I put the bushings in the right way as I have the assembly manual.  I put the bushings in the way I have them now the first time and the issue was obvious when I laid the first fender on the car.  So I went through several iterations of pulling the subframe, changing the bushings around, switching the order in which I tightened, etc.  I tried about everything I could think of.  The holes all line up fine, so I didn't think the subframe was bent.  However, I did notice that the subframe has had one of those mount repair kits welded in.  Whomever put the repair kit in cut out the top of the rear subframe and welded the 1/4" plate in. They welded the firewall mount repair underneath the existing subframe mount - so it seems like the rear subframe mounts are ~ 1/8" higher than they would be stock, and then the firewall mounts would be the same - but I don't have another subframe to compare it to.  My thinking was that this would pull the rear of the subframe down a little bit and cause the subframe to sit tilted. Run that small tilt all the way out to where the radiator support is and it might be the problem as it would sit higher.  So I had a friend of mine who is a machinist make me some spacers 1/4", 3/8", and 1/2" thick that I could put on top of the firewall bushings.  The thicker the spacer, the better the gap gets.  With the 1/2" spacers in, the gap is the best, but it looks like I'd need about 3/4" spacers to get it even.  Something about that just didn't seem right to me. It didn't seem like that little difference would justify needing 3/4" more spacing a couple feet forward where the firewall mounts hook up. I even dusted off the geometry skills to try and figure it out.

So thanks again for the help - I just want to make sure I find out what the problem really is, as fixing it later would be much more work. 

dmleonard

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Re: New subframe bushings and fender alignment problem
« Reply #9 on: June 13, 2008, 11:05:37 PM »
I got everything level and plumb and...... Still need the 3/4" of spacing on the firewall bushings.  ??? With those in, everything lines up and is level.   Unless someone knows the thickness of the bushings, I am going to order a new set just to make sure they are right.  Door gaps are good, so I don't think the body is tweaked.  Very, very frustrating.

Barefoot Dave

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Re: New subframe bushings and fender alignment problem
« Reply #10 on: June 14, 2008, 12:22:57 AM »
Do you still have the old bushings? If so at least take a look at them and compare them to the new ones. I've installed several sets that D&R sells and I've never had any trouble except that if the old ones were really bad you'll definitely have gap issues since the whole front end rides on the subframe via the radiator support and if you change it's location even a little you'll have to adjust and shim the front end sheetmetal.
Dave Miller
Fairfax VA

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69 BB Z-10

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Sauron327

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Re: New subframe bushings and fender alignment problem
« Reply #11 on: June 14, 2008, 02:17:41 AM »
 Wow. Never had this dilemma before. Not being there does not help. Your reworked frame may be a problem. But lets take a reverse approach first. With the car on our lift we  dropped the subframe out of a rust free uncut 69 to re-detail the sub-frame and components. The front clip was left in place(minus the hood of course).  The clip doesn't need the subframe to establish proper door to fender gaps. Detailed the subframe and put it back in place like clockwork. I do not assemble cars this way but am using this scenario as an example.--Endulge me for a moment. Establish proper door to quarter and door to rocker gaps(assuming origional metal or properly installed metal we hope). Hang fenders, radiator support and braces and establish proper fender to door gaps and tighten appropriately.(Assuming GM fenders or non-reject aftermarkets)  Now with your bushings in the proper places the subframe should bolt in place relatively close allowing for some slight bushing crush. It has no choice. Any botched frame repairs, inconsistencies or  measurement variations will now be evident. Keep in mind until you put hood and subfame in you may have some nose rack but we are trying to diagnose a vertical  problem first. Nose rack is a cake walk.