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Old 02-12-2015, 03:04 PM   #1
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Plan to use 4th gen k-member in 3rd gen

As some of you Im planning on doing an LS1 swap into my '88 GTA.

Which k member to use is one big decision I need to make.
I could go tubular but then I run into issues about if the A/C compressor fits or not and about how stock braces fit or don't fit. Then I have to see what a-arms fit, mods needed for stock one etc. It would be like 1,000 to do a tubular setup correctly. I don't really NEED the extra clearance one gives me nor the weight reduction. It has also been said the small tube on the bottom doesn't provide much protection to the oil pan if you go over something.

Another option is to mod the stock k member. I would need to notch the front for the a/c compressor and either notch the rear for needed oil pan clearance or buy a new oil pan. That was the option I was leaning towards.

Then I got to thinking, that I would love to use the entire chassis harness from the Formula and run traction control and ABS as well. That would involve having a front speed sensor somehow. If i used 4th gen spindles, it would be easy.

I looked online and the general consensus is that its not worth the time or effort to make a 4th gen k member fit. No one has tried it. One person has used the full front clip from a 4th gen a welded it to the firewall of a 3rd gen and put 3rd gen sheet metal on it, worked great for them but I don't want to go that crazy. Another benefit of the 4th gen setup would be rack and pinion steering and taking stress off the 3rd gen frame which is know to crack by the oem steering box. With the 4th gen k, I'd be able to fit a/c like stock as well as the f body oil pan.

My thoughts for this are largely based on what I remember of the two k members and how I think they would almost line up. The mounting point are at different levels I think so that would be the main change. I have 4 4the gen k members to work with/cut up. I was even thinking I could cut out the bottom of the 3rd gen "frame rails" where the k mounts, weld in a small section of box steel tube, and then close it back up with the lower section of the "frame" rail cut off one of my 2 4th gen parts cars. That way it would always remain a bolt on setup. Obviously a lot of measurements would need to be taken to make sure wheelbase remains the same, and that the engine centerline and setback are all correct. The 4th gen struts would mount to the top of the current shock towers, which I would reinforce. But even thinking about that, They make coil over 3rd gen setups that put the stress on those towers with no mods and they hold up fine.

Yes, I know its not a simple plug and play install and it would require a significant amount of fabrication. But that's what I would like to have on the car so why shouldn't I try it. If i can get away with only modding the k member and not touching the GTAs unibody, what do I have to lose.

What are your opinions of this? Its not like my GTA is gonna be on the road anytime soon so I have the time to mess around with it.
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Old 02-12-2015, 04:23 PM   #2
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seems like a lot of work for minimal return. and honestly a lot of that is over your head.
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The looser the waistband, the deeper the quicksand. Or so I have read.

Feather-light suspension, Konis just couldn't hold. I'm so glad I took a look inside your showroom doors.

Hey everybody, it's good to have you on the Baba-too-da-ba-too-ba-ba-buh-doo-ga-ga-bop-a-dop
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Old 02-12-2015, 05:07 PM   #3
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That is the only con. I would be doing the majority of the design and cutting, with a professional doing the actual welding on the k member.
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Old 02-12-2015, 05:33 PM   #4
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what is the intended usage of the car?

BTW i mean the design part is over your head
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Vent Windows Forever! ... My junk ... NJ Camaros and Firebirds

The looser the waistband, the deeper the quicksand. Or so I have read.

Feather-light suspension, Konis just couldn't hold. I'm so glad I took a look inside your showroom doors.

Hey everybody, it's good to have you on the Baba-too-da-ba-too-ba-ba-buh-doo-ga-ga-bop-a-dop

Last edited by BonzoHansen; 02-12-2015 at 05:34 PM.
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Old 02-12-2015, 07:05 PM   #5
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http://www.paracing.com/racingstore/...0q24m0q32htbs7

I think that is a much cheaper and easier route when all said and done.
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Old 02-12-2015, 08:58 PM   #6
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I'd first look over all the parts, measurements, clearances, etc and draw it all out in Autocad prior to making any cuts. I might realize it wont work way before that.

The intended usage would be a weekend fun car, a cruiser/showcar , and maybe a few passes down the track, like one day a year or so.


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Originally Posted by sweetbmxrider View Post
http://www.paracing.com/racingstore/...0q24m0q32htbs7

I think that is a much cheaper and easier route when all said and done.
That's comes out to be 499 plus its recommended to get tubular a arms, and then i still don't have rack and pinion or abs ability.

If i feel like dropping around 900 on front suspension though I would get the PA one.

Last edited by V; 02-12-2015 at 08:59 PM.
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Old 02-12-2015, 09:08 PM   #7
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Take the LT1 K-Member out of my driveway, cut away!
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Old 02-12-2015, 09:45 PM   #8
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Quote:
Originally Posted by V View Post
The intended usage would be a weekend fun car, a cruiser/showcar , and maybe a few passes down the track, like one day a year or so..
then honestly what you propose is a total waste of time, money and effort. A quality steering box with a 'wonder bar', good springs & shocks, rebuild the LCA with global west del-a-lum bushings, rebuild the front end with moog or pro-foprged parts (if they make 3rd gen parts) and your done. Hell, if it has the big sway bars already you wont even need more than bushings there either. Honestly the steering box is the most expensive thing I listed if you get a good one like a Tom Lee built box, which will feel as good as any R&P. Not a crap shoot parts store rebuild. Set the alignment up at like 6* caster, -1* camber and a wee bit of toe in and you are gold. With good tires you'll be very happy. I propose a weekend of work that is easy to do vs a year of effort with little chance of improvement and a higher chance of fail. Just my $0.02 from experience.
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Vent Windows Forever! ... My junk ... NJ Camaros and Firebirds

The looser the waistband, the deeper the quicksand. Or so I have read.

Feather-light suspension, Konis just couldn't hold. I'm so glad I took a look inside your showroom doors.

Hey everybody, it's good to have you on the Baba-too-da-ba-too-ba-ba-buh-doo-ga-ga-bop-a-dop

Last edited by BonzoHansen; 02-12-2015 at 09:46 PM.
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Old 02-12-2015, 10:01 PM   #9
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Yea, you do have good points. If I stay with the stock K, I'm just going to have to see how to add the k member braces back since the pass sides attaches where the a/c notch will be.
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Old 02-13-2015, 12:21 AM   #10
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Or get different ac mounts. There are different options out there besides factory

If you were willing to cut the crap out of the car, what's the problem with a boxed notch?
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Vent Windows Forever! ... My junk ... NJ Camaros and Firebirds

The looser the waistband, the deeper the quicksand. Or so I have read.

Feather-light suspension, Konis just couldn't hold. I'm so glad I took a look inside your showroom doors.

Hey everybody, it's good to have you on the Baba-too-da-ba-too-ba-ba-buh-doo-ga-ga-bop-a-dop

Last edited by BonzoHansen; 02-13-2015 at 12:22 AM.
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Old 02-13-2015, 06:26 AM   #11
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Have you considered a similar plan using a C5/6/7 front? It is a vastly better set up and if memory serves the wheel mount to wheel mount widths are pretty close.
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Old 02-13-2015, 09:53 AM   #12
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Lol
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Vent Windows Forever! ... My junk ... NJ Camaros and Firebirds

The looser the waistband, the deeper the quicksand. Or so I have read.

Feather-light suspension, Konis just couldn't hold. I'm so glad I took a look inside your showroom doors.

Hey everybody, it's good to have you on the Baba-too-da-ba-too-ba-ba-buh-doo-ga-ga-bop-a-dop
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Old 02-14-2015, 05:04 PM   #13
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Just buy the Holley AC mount. It puts the 3rd gen AC compressor up by the passenger head. You can use the factory alternator and PS bracket that comes with the LS1. I believe it is under $200 for everything. I did it on my LS6 conversion on my 73 Camaro and I didn't even need to disconnect my AC compressor. The bracket put the compressor in the same place as my TPI serpentine brackets I had.
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Old 02-14-2015, 06:15 PM   #14
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Quote:
Originally Posted by amargari View Post
Just buy the Holley AC mount. It puts the 3rd gen AC compressor up by the passenger head. You can use the factory alternator and PS bracket that comes with the LS1. I believe it is under $200 for everything. I did it on my LS6 conversion on my 73 Camaro and I didn't even need to disconnect my AC compressor. The bracket put the compressor in the same place as my TPI serpentine brackets I had.

Do you have a possible link for that bracket? I would consider that.



edit: I found the part. Its $140(give or take a few bucks).
In comparison, the k member notch kit to run the LS compressor is $30(plus welding), and then the conversion a/c hoses are $150.

If I use the Holley mount, I don't have to notch, I can still keep the chassis brace in place, I can use the stock tpi a/c compressor and hoses, so I'd actually save 40-50 bucks easily. The holley piece even looks like the oem cast aluminum brackets, no shiny billet crud. I guess the solution is clear, Holley mount it will be.

edit#2: Actually it seems like I need a $70 installation kit for the holley setup as well plus a smooth pulley. But still seems like the best option.

Now... tell me more about upgraded steering box options... I never actually thought about them. I'm more used to r&p setups.

Last edited by V; 02-14-2015 at 07:22 PM.
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Old 02-15-2015, 10:55 AM   #15
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I see you found everything, but yes you need the bracket and the install kit. I really like the Holly mount because it looks factory. Here is a link to me installing it on my 73

http://www.apiem.com/camaro/LS6PT420141006.asp

Here it is installed using the CTS-V accessories.

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Old 02-15-2015, 12:25 PM   #16
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I see you found everything, but yes you need the bracket and the install kit.
I read that the ribbed idler pulley is from the tensioner and gets moved up top but where does the smooth pulley come from? I couldn't find it anywhere listed on holleys site about where it comes from. I know the stock pulley setups have a smooth pulley down on the drivers side by the alt but if I'm still using that side, I obviously can't take that pulley. I do have 2 complete ls1 engines so i have a spare, BUT is that the right pulley?
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Old 02-15-2015, 12:49 PM   #17
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Go to the Holley site and download all the install documentation. They list the part numbers there. I believe I purchased a Dayco pulley and it wasn't that much.
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Old 02-15-2015, 01:21 PM   #18
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Ah ok, now I found it. they have a holley part number, 97-150, and gm number, 12564401.
The Holley part is just 37 bucks. Or 50 from GM with all washers and the bolt.
It does appear to be the same as the smooth idler by the alt, so I can just use the spare one I have or I may have one left over from when I put the blower on my CTSV.
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