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mrscottly
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Is there a question here?
Saturday, January 19, 2008 4:57 PM
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Troux
Valrico
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Yes.
quote :
Cliffs: Measured my subframe, and the engine can't mount evenly on it. Opinions?
Got my subframe today. I got a shipment of two of them, being mine and Aaron1017's. Total weight of the package was 37.0 pounds. Figuring a pound of packing materials, that puts them at right around 18 pounds each. Nice. I believe stock is 21, but jimlab would know these numbers better.
I took a caliper to them as soon as I unwrapped the package, and here's where I found an error. The "mounting points" I'm referring to are the centermost structures in the following picture, where the engine mounts bolt to.
Measuring the engine mounting points, one of the subframes seemed to be very close to even, and the other one had noticeably different angles. The height of the rear faces of these mounting points (the face hidden in the above picture) were about identical, and the height of the front faces (the measurement marked in [color=red]RED[/color]) were 30.5mm on one side and 36.5mm on the other side.
To find out how much of a difference this would make, I flipped the subframe upside down on a flat surface and measured the angles that these mounting points made with respect to a flat surface. The subframes were resting flat on the tops of the front chassis mounting points (right most structure in the foreground of the above picture), so this was a good representation of how the engine mounts would sit in relation to the car. On the seemingly "correct" subframe, one side seemed to sit about 1 mm higher than the other. Negligible and completely allowable, but most notably is that they were both almost completely parallel to the ground. I'd say less than 0.5 degrees off parallel, with very even angles between the two sides.
On the other subframe, one side was about 1.6 degrees off the parallel, and the other side was about 6.0 degrees off the parallel. This means the engine would be unable to sit flat on both mounting points of the subframe, and a difference of 4.4 degrees between the two sides seems pretty large.
Impressed with one subframe, but I'm curious if the other is something I need to look into getting replaced, or if I'm overthinking this. Thanks in advance for your input.
P.S. Sorry I couldn't include pictures of my measurements, but I was having a hard time getting any that could show what's apparent in-person. I carefully measured multiple times, so let's just assume my numbers are reliable. .gif) |
Sunday, January 20, 2008 11:36 AM
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mrscottly
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A question or two comes to mind: Are both your car and his the same year, with the same factory installed drive train/engine size?
If so, the I would call the supplier and question why the difference in these two pieces. If the piece was built in a sturdy jig (which it should have been), the parts would not have moved during the welding process, as they would had this part not been welded in a jig.
If they didn't use a jig, then they are not building a quality piece.
I get the feeling that the difference exists to compensate for differences in the body from two different model years.
quote :
On the other subframe, one side was about 1.6 degrees off the parallel, and the other side was about 6.0 degrees off the parallel. This means the engine would be unable to sit flat on both mounting points of the subframe, and a difference of 4.4 degrees between the two sides seems pretty large. |
Unable to sit flat, if the subframe is designed to be flat. If I am reading this correctly, you could bolt the engine to the subframe, but the subframe would angle from side to side. This is what makes me believe there were design changes in the body mounting points in the car.
Monday, January 21, 2008 9:37 AM
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Troux
Valrico
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Both of the subframes I'm comparing are same model year, for the same engine, using the same motor mounts, and supposed to be the same design 100%. Definitely getting a call from me. It's custom, small production parts, so I expect a little extra tolerance, but there's some serious error here. Upon test fitting, not only is it missing a bolt hole (an obvious sign of an abridged or nonexistant jig), but the control arm mounting points are too close together, and misangled, so that if you can fit one of the bushings into the subframe, you would have to pry the subframe apart slightly (bottle jack, likely), just to get the other mount of the control arm to fit in crookedly!
They were supposedly using a jig and as much CNC'ing as possible to avoid variations, but I'm seeing some serious QC issues here.
Unfortunately, I seem to have miscommunicated the angle problem to you. The subframe actually IS designed to be flat, and set the motor (at least the mounts) flat, parallel with the car. On the subframe that seemed to be in spec, this is the case. The motor mount stands on the subframe are angled slightly backward, so that the front of the motor would be pointing upwards. On top of this error, each angle is different, so that one motor mount would sit at a 1.6 degree angle toward the sky, and the other is angled 6 degrees towards the sky. Theoretically, if the engine were to be mounted to the subframe, the subframe (assuming it's more rigid than the engine of course) would be twisted, which of course isn't a viable option.
I remembered the subframe fabber posted pictures of these in production, giving a couple clues.
They were all made without the required number of holes to bolt to the chassis (these need 3 holes, which is the missing hole I mentioned above)
Mounting point:
Mounting brackets: 
They also clearly showed their customers that they weren't welding on a jig:
[Edited by Troux on 1/21/2008 10:36:28 AM. Reason for edit: Clarification.]
Monday, January 21, 2008 3:14 PM
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mrscottly
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I've been welding with OXy-Acet, MIG, TIG, and stick for the better part of 20 years. It's no secret that heat will pull the metal in different directions. The only way to maintain consistant, time-over-time quality is to weld in a rigid jig, and even then it's important to maintain room temperature at a constant. It sounds as though these pieces were just not made to very rigid quality standards.
One other thing glares at me....it appears that the components to the finished product were stamped in a punch press, so it puzzles me why there would be a hole missing. That being said, although you both have the same car, it may be possible that they sent you one for a different model year than what you have. Could be as simple as a parts bin mix-up.
You can send it back, or if you can weld, you can fix it yourself. Not easy, but if it were me, I'd fix it myself then spread the bad word about this company to everyone I know. There's no excuses for the kind of vairances that you are showing me.
[Edited by MrScottly on 1/21/2008 12:37:43 PM. Reason for edit: ..]
Monday, January 21, 2008 5:33 PM
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Troux
Valrico
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He actually only supplies these subframes for one generation of one car ('93+ Mazda RX-7) and for one motor (LS series Chevy), so you'd think he could get it right... Talked to him today. Most likely sending it back. It probably COULD be fixed with welding, but for what I paid and how long I waited, I'd like to get it the way it's meant to be.
Wednesday, January 23, 2008 7:34 AM
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