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ConvertiblesDiscussed here are problems and solutions to convertible specific questions, including difficult to find part numbers and other convertible tech help.
Im looking into purchasing a set of subframe connectors for my 1991 convertible. I've seen on TOP DOWN SOLUTIONS website (Sub-Frame Connectors, 82-92 Camaro or Firebird (top-downsolutions.com)) where they talk about the Alston Racing version being the only ones that work with the ASC built convertibles. Ive seen that the UMI ones seem to have more bracing and are said to work on convertibles as well so I thought about going with them instead. Has anyone tried any of the other brands other than the Alston ones?
I have Alstons on the inner, and Spohn outter sides.
I have a 91 Trans Am convertible and my car as I'm sure yours is also has a boxed section running down both sills. You won't be able to add subframe connnectors down the sides of your car unless you take out those boxed additions which is a major job. I used to make subframe connectors and I was going to put them down the sides but found out that I could not. I bought Aliston connectors from Top Down Solutions and they work well along with what I already have. Have you not looked at that? Hope that helps.
I have a 91 Trans Am convertible and my car as I'm sure yours is also has a boxed section running down both sills. You won't be able to add subframe connnectors down the sides of your car unless you take out those boxed additions which is a major job. I used to make subframe connectors and I was going to put them down the sides but found out that I could not. I bought Aliston connectors from Top Down Solutions and they work well along with what I already have. Have you not looked at that? Hope that helps.
Yes I’ve seen the Alston ones on Summit and the TDS website. I just thought that the ones that UMI made looked beefier, had more mounting points, etc. I emailed UMI and they said they had not had any trouble with the bracing under the ASC cars.
Was the Alston braces alone enough for a convertible?
You won't be able to add subframe connnectors down the sides of your car unless you take out those boxed additions which is a major job.
I'm sorry. Are you telling me that I cannot add the subframe connectors to my car? You know, the ones that are ALREADY on my car. So you are saying that these won't fit on my car:
I'm sorry. Are you telling me that I cannot add the subframe connectors to my car? You know, the ones that are ALREADY on my car. So you are saying that these won't fit on my car:
The 91 and 92 convertibles came with a boxed section on the sills from front to back. The way subframe connectors are attached are to the sills. I was going to put a heavier style of connector on mine until I saw how the boxed sections are attached. They have really large rivets and I didn't want to disturb it. I have added connectors that attach more on the center of the car (Alliston). Please tell me that I am wrong?
Sorry, but you can add them to the sides. I also have the TDS units in the center and the global west (which are NOT even designed for verts), but with a little modification i was able to fit and weld them on. I went with GW because they are tubular like the TDS connectors.
I personally install both types of Sub-Frame Connectors on every Customers Solid-Roof and T-Top Third-Gen.
I make my own versions of each design In-House (it is easier to fit and correct twisted Uni-Bodies this way).
On Convertible Cars, I go even further by connecting by types of Sub-Frame Connectors in many places to further stiffen the Uni-Body.
I also do this for all high HP Non-Convertibles (I will not install a high HP Engine in a Convertible).
Yes, those are the two pairs that I have installed. I got my Alstons from Lon at TopDownSolutions (trying to support small business and one that is a big supporter of TGO).
Sorry, but you can add them to the sides. I also have the TDS units in the center and the global west (which are NOT even designed for verts), but with a little modification i was able to fit and weld them on. I went with GW because they are tubular like the TDS connectors.
I have the GW connectors on my GTA. I really like them and would have bought them again if they fit convertibles. They didn't (without modifications) so I went with the Spohns since they were designed for verts (without modifications to the SFC or car).
The 91 and 92 convertibles came with a boxed section on the sills from front to back. The way subframe connectors are attached are to the sills. I was going to put a heavier style of connector on mine until I saw how the boxed sections are attached. They have really large rivets and I didn't want to disturb it. I have added connectors that attach more on the center of the car (Alliston). Please tell me that I am wrong?
You are completely correct in how the car was built. However, YES you can add SFCs without modifying the car. For reference, here is my car:
I have the GW connectors on my GTA. I really like them and would have bought them again if they fit convertibles. They didn't (without modifications) so I went with the Spohns since they were designed for verts (without modifications to the SFC or car).
They didn't need much modding. Just cut off the rear mounting plate about 1/2 past the weld. Cap the open end and weld them on. Don't all verts have that boxed section on the sills?
Passenger.
Driver side.
If you have the ability and or means to pay for the fab work, the DSE subframes are IMHO the best out there. They truly connect front and rear suframes with full welds down the length. Higher cost of entry, but final fit is as if there were OEM and the stiffness they add is unparalleled.
If you had to do it again would you have installed both sets or just the Alstons?
The 91-92 Firebird convertibles were built by ASC too weren’t they? So they share the same bracing that ASC added
Yes, all '91-92 F-body convertibles were built by ASC. I don't see any reason to not install both sets. I don't know what having only the Alstons would do. I had both sets installed at the same time.
Yes, all '91-92 F-body convertibles were built by ASC. I don't see any reason to not install both sets. I don't know what having only the Alstons would do. I had both sets installed at the same time.
I guess I’m confused a little…. I don’t see how it’s possible to install both sets.
Weren’t all the Third Gen Vert F Bodies, converted by ASC? My ‘89 IROC Z Vert has the ASC LABEL and the reinforced rocker panels. We’re the factory rocker reinforcements changed over the Third Gen run?
I am restoring my IROC Z Vert for resale and am debating if I should install Subframe Connectors. Probably would add zero value and might be a negative in an otherwise
stock car. What say youse?
Weren’t all the Third Gen Vert F Bodies, converted by ASC? My ‘89 IROC Z Vert has the ASC LABEL and the reinforced rocker panels. We’re the factory rocker reinforcements changed over the Third Gen run?
I am restoring my IROC Z Vert for resale and am debating if I should install Subframe Connectors. Probably would add zero value and might be a negative in an otherwise
stock car. What say youse?
If you are doing a factory restore then I would not add them, there is a potential for $ loss. If you are doing a restore to make it sellable then I would for sure. I would just do the Alston's at that point. I am very happy with mine and I had a competent muffler shop weld them in. If you have your interior in it is imperative they know what they are doing to control the heat of welding. I can't say for sure how much both helps but I will say it was a major difference by just adding the Alstons.
In looking at all these photos you guys posted do you think it would be possible to have 4 tubes fabricated to go from the brackets on the Alstons to the angle rail on the rocker and weld them direct? I can see where the addition of that side tube welded to the angle would help but it just seems a little overkill as you already have a support there. Plus that support is riveted in place so I would think if the welder can tack that ASC support to the body at the same time IMHO would work much better. If you weld that tube to the angle and don't weld the angle I think it would put more stress on the rivets that hold the angle in place...
I have a new set of the Alston Inner connectors I was going to list for sale. I bought them when I had my 89 Formula 350 vert. Did not put them on when I found it had N10 and didn't want to alter such a rare car. Anyway - let me know if you're interested. I'll post a FS listing soon.
I have a new set of the Alston Inner connectors I was going to list for sale. I bought them when I had my 89 Formula 350 vert. Did not put them on when I found it had N10 and didn't want to alter such a rare car. Anyway - let me know if you're interested. I'll post a FS listing soon.
If you still have them around, what would you be looking to get for them? I might be interested.
You are completely correct in how the car was built. However, YES you can add SFCs without modifying the car. For reference, here is my car:
WOW! That is a lot of bracing and appear to be a clean, quality install! Please describe the improvements you experienced, after the install. NVH (Noise Vibration Harshness) improvement, stiffness of the unibody, rattles/squeaks. Can you tell if they might interfere with service and repair, in the future? I think I'm gonna have a body shop check my 89 IROC Z Vert for "frame straightness " (as thirdgen.org "vorteciroc" suggested) and copy your install.
WOW! That is a lot of bracing and appear to be a clean, quality install! Please describe the improvements you experienced, after the install. NVH (Noise Vibration Harshness) improvement, stiffness of the unibody, rattles/squeaks. Can you tell if they might interfere with service and repair, in the future? I think I'm gonna have a body shop check my 89 IROC Z Vert for "frame straightness " (as thirdgen.org "vorteciroc" suggested) and copy your install.
It did cut down the NVH quite a bit. However, it didn't cut it down as much as my Global West SFCs that I installed on my GTA, but I attribute that to the fact that my GTA is T-top vice vert and the convertible had north of 120,000 miles when the SFCs were finally installed. They did help the daily drivability though. Much more consistent reaction to driving/steering inputs. I went with both inner and outer SFCs due to it being a convertible and I personally believe they need all the help that they can get with bracing. It also has a BMR STB as well.
I don't think that either of the SFCs will impact any serviceability in the future at all. The issue most people have with them is exhaust pipe interference. The inner Alstons did not have any issues with that. One of the things that I always look for when making improvements to my cars is that they fit most factory locations/can be undone if they don't work the way I want. Just my opinion, but when you do that it eliminates (or grossly minimizes) the issue related to using parts from different manufacturers (if that makes sense).
Hope that helps. Feel free to ask any other questions.
09-29-2021, 07:41 PM
