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Subframe mod question

Old 02-24-2018, 04:04 PM
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Subframe mod question

Got to thinking, Thirdgens have two big complaints against them from the car world
1: exhaust clearance! It's terrible, there's no room for any decent dual pipe to tuck happily.
2: The "thirdgen" squeaks, clunks, rattles from chassis flex.

So I've been poking around different threads to maybe find a fix for these problems. It seems that the common denominator is the front frame boxes. They cause most of the issue. We often mitigate the problem with subframe connectors but still don't have the clearance we need for exhaust.

Is it possible to completely remove the frame boxes and "frame" the car? tie one bar from the front frame to the back frame on each side. I mean, we already buy a giant bar with subframe connectors, why not connect the subframes through the floor. Strengthen the chassis AND be able to run exhaust under the tunnel. Granted it's a longer, tougher road but I see significant benefits over the typical flight pattern.
Any thoughts or insight on this?
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Old 03-31-2018, 04:41 PM
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Re: Subframe mod question




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There is PLENTY of room down there as you can see in the pictures. All of those items are installed on that car in the side view shot, great ground clearance. The converters are the lowest point of the system, if removed it would then be the headers. Nothing touches any other component, nothing bangs or rattles, nothing is crushed to fit, the system is round from front to rear.
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Old 04-21-2018, 04:00 PM
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Re: Subframe mod question

What converters are those?
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Old 04-21-2018, 04:26 PM
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Re: Subframe mod question

What size is your exhaust tubing?
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Old 04-21-2018, 04:59 PM
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Re: Subframe mod question

Those are Random Technologies free flow cats for 2 1/2 inch tubing. They are awfully similar to the factory cats on my 99 silverado.
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Old 04-21-2018, 06:23 PM
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Re: Subframe mod question

hey 91ls1t56, you plan on selling that spohn crossmember now that you made your own? I'll take it off your hands
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Old 04-26-2018, 06:16 AM
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Re: Subframe mod question

Originally Posted by 91ls1t56 View Post




There is PLENTY of room down there as you can see in the pictures. All of those items are installed on that car in the side view shot, great ground clearance. The converters are the lowest point of the system, if removed it would then be the headers. Nothing touches any other component, nothing bangs or rattles, nothing is crushed to fit, the system is round from front to rear.
Are those subframe connectors something you made or something someone is making for these cars?
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Old 04-26-2018, 05:32 PM
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Re: Subframe mod question

I made the frame connectors along with the crossmember, they all bolt up and work together.
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Old 07-21-2018, 12:51 PM
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Re: Subframe mod question

I would say that is some very good fabing and welding. I would buy those in a heart beat. They look clean and fit like a charm. My duals dump out by under the axle. I don't get emission tested so no coverters and race bullet mufflers on mine.
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Old 07-27-2018, 03:12 PM
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Re: Subframe mod question

Originally Posted by tubesncubes View Post

Is it possible to completely remove the frame boxes and "frame" the car? tie one bar from the front frame to the back frame on each side. I mean, we already buy a giant bar with subframe connectors, why not connect the subframes through the floor. Strengthen the chassis AND be able to run exhaust under the tunnel. Granted it's a longer, tougher road but I see significant benefits over the typical flight pattern.
Any thoughts or insight on this?

The DSE subframe connectors basically do exactly this. You cut through the floor, and their kit ties the front frame to the rear. When installed it is no lower than your pinch weld (which also is typically chewed up).
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Old 08-01-2018, 06:54 PM
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Re: Subframe mod question

i like the look and function of the Detroit speed sfc's they tie in well and have no ground clearance issues but I'm not going over the rear for exhaust either.
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Old 08-02-2018, 11:11 AM
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Re: Subframe mod question

If you can weld decently, have a chop saw and can buy the appropriate metal then buying sudframe connectors is a big waste of money vs making your own. Case in point, the solid motor mounts spohn makes sell for $150 and I made my own copy for $5-10. I did the same for my inner subframe connectors. Members on here have also removed the factory subframe rails and welded in their own, that's something I wish I had done on my car!
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Old 08-02-2018, 11:48 AM
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Re: Subframe mod question

Originally Posted by Tibo View Post
If you can weld decently, have a chop saw and can buy the appropriate metal then buying sudframe connectors is a big waste of money vs making your own. Case in point, the solid motor mounts spohn makes sell for $150 and I made my own copy for $5-10. I did the same for my inner subframe connectors. Members on here have also removed the factory subframe rails and welded in their own, that's something I wish I had done on my car!
I agree but it's all in the opportunity cost. Some folks, party included, have very limited time, so much so that a few hundred bucks is cheaper than our time. However, to your point, these cars are simple enough where DIY fab work is very doable and cost effective.
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Old 08-02-2018, 04:40 PM
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Re: Subframe mod question

Originally Posted by ShiftyCapone View Post
I agree but it's all in the opportunity cost. Some folks, party included, have very limited time, so much so that a few hundred bucks is cheaper than our time. However, to your point, these cars are simple enough where DIY fab work is very doable and cost effective.
Unfortunately just throwing money at it to save time doesn't always work. I spent money on what I thought were good products and ended up so frustrated I had to make my own after all.
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Old 08-02-2018, 11:54 PM
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Re: Subframe mod question

Originally Posted by 91ls1t56 View Post
Unfortunately just throwing money at it to save time doesn't always work. I spent money on what I thought were good products and ended up so frustrated I had to make my own after all.
I understand what shifty is saying but I think you and I are of a similar mindset now. I've read about and had enough experience with ill fitting products that, if possible, make me want to fabricate my own parts.

Last edited by Tibo; 11-04-2018 at 09:39 AM.
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