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LTX and LSXPutting LT1s, LS1s, and their variants into Third Gens is becoming more popular. This board is for those who are doing and have done the swaps so they can discuss all of their technical aspects including repairs, swap info, and performance upgrades.
I bought the running Gen III 4.8, engine & transmission two years ago. I am just getting around to starting the swap. We tore the motor down to the shortblock inspected the bottom end and replaced all gaskets, timing set, rebuilt 862 heads with 32k mile ls6 springs, new injectors,sensors,water pump,oil pump,f body oil pan kit, speed engineering headers, the works..
I've reworked the factory harness. Run video below
Me and a friend are swapping in a 4th gen rear thisweekend, and hopefully installing the engine/transmission next weekend.
I plan on using all truck serpentine accessories. Ive read somewhere on this site where someone was successful but I have to re find that thread..
Any tips on installing the 4th gen rear? I already have some new shocks
The 4th gen rear will bolt right in. You can even modify your parking brake cable to get it to work as well (assuming you had rear disks). If not, a new one from rock auto and 5 minutes with a grinder will get the job done. The 4th gen rear is wider than the 3rd gen wheel by 1.5" or so a side so your wheels will stick out if you keep the stock backspacing. Now would be a good time to put in a small cam to wake that 4.8 up
The 4th gen rear will bolt right in. You can even modify your parking brake cable to get it to work as well (assuming you had rear disks). If not, a new one from rock auto and 5 minutes with a grinder will get the job done. The 4th gen rear is wider than the 3rd gen wheel by 1.5" or so a side so your wheels will stick out if you keep the stock backspacing. Now would be a good time to put in a small cam to wake that 4.8 up
The factory rear is a drum non posi rear end... Would you happen to have a part # for that parking brake cable I need?
I would love to put a cam in it but the guy wants to charge me $400 for a regular street tune, and then I might as well put a converter in if Ima do that... Adds up... Unless someone can help me with a tune in South Louisiana
Does anyone know if the rubber brake hose that connects with the t fitting connecting to the hard brake lines for the rear brakes will fit on the rear swap?
Would the rubber hose and the \"T" piece that connects the two hard brake lines of the third gen drum rear end fit? Or what would I have to do to make this work?
Last edited by 86iroc504; 12-05-2019 at 06:50 PM.
Reason: Edit added picture
The 4th gen rear will bolt right in. You can even modify your parking brake cable to get it to work as well (assuming you had rear disks). If not, a new one from rock auto and 5 minutes with a grinder will get the job done. The 4th gen rear is wider than the 3rd gen wheel by 1.5" or so a side so your wheels will stick out if you keep the stock backspacing. Now would be a good time to put in a small cam to wake that 4.8 up
Hey bro can you be more specific on how to make the 4th gen parking brake work with stock thirdgen?
Does anyone know if the rubber brake hose that connects with the t fitting connecting to the hard brake lines for the rear brakes will fit on the rear swap?
Would the rubber hose and the "T" piece that connects the two hard brake lines of the third gen drum rear end fit? Or what would I have to do to make this work?
Hey man I didn’t realized you’d made a thread here...I think when I swapped to the 4th gen rear I had an issue with the brake line compatibility if I remember right. I think everything I read at the time said it was suppose to fit but it didn’t. I had to buy a few different pieces before I got the right one.
I can climb under my car this evening and check for a part number #, but my car was a 9 bolt before the 4th gen swap so things may be different
Hey man I didn’t realized you’d made a thread here...I think when I swapped to the 4th gen rear I had an issue with the brake line compatibility if I remember right. I think everything I read at the time said it was suppose to fit but it didn’t. I had to buy a few different pieces before I got the right one.
I can climb under my car this evening and check for a part number #, but my car was a 9 bolt before the 4th gen swap so things may be different
Yea thats fine if you could. I ordered (2) e brake cables from a 90 Camaro with the disk break rear.. I read somewhere it would work but we'll see tomorrow
I could be wrong but I think I’ve read that people use e brake cables off a 92? I never got around to that part but I think I’ve read that
According to Amazon, it fits the 92 also.. I'll see what happens tomorrow for sure.. I think it's the end piece that goes to the 4th gen rear that gives people problems
Went to go do the front coils and struts and decided just to take everything out and change all front end bushings... and new tie rods.. Everything else I will just sand and paint.. We will also install the motor/tranny from the bottom before we reassemble front end.. Im using some lsx innovations setback plates, sbc engine mounts, and Moroso solid mounts attached to the setback plate.. Has anybody done this setup before?
I used the UMI LS swap mounts with the factory LS1 clamshells. leave them loose and once you get the through-bolt for the engine mount bolted in, you can torque down your engine mount brackets (k-member side). They slide forward and back but I was able to put mine fairly close to k-member without notching it, and I'm still comfortable with my oil pan clearance from k-member. I used the fbody pan as well. https://www.umiperformance.com/home/...e-swap-mounts/
Last edited by cmiller2014; 12-30-2019 at 02:07 PM.
Reason: added link
My setup. Does anyone know where the clamshells should be on the plates to keep everything in the factory position to keep my stock driveshaft? My motor mounts are position all the way to the front on k member
I used cheapo set back plates and factory sbc mounts. Mine could only be bolted up one way so I’m not sure what to tell ya on that. No instructions? Maybe scan YouTube or check their website.
if all you need to know is how much set back, my plates were 1” set back.
Not 100% sure but I'm pretty sure your oil pan won't clear technically in the exact factory position unless you notch your k member. It's all relative but since it looks like you have your k member out I'd suggest putting it on out of the car and see how you like the clearance. Your mounts have enough leeway to either not clear the kmember or for the drivers side head to hit the firewall, and I know that doesn't help you much.
I used cheapo set back plates and factory sbc mounts. Mine could only be bolted up one way so I’m not sure what to tell ya on that. No instructions? Maybe scan YouTube or check their website.
if all you need to know is how much set back, my plates were 1” set back.
Originally Posted by cmiller2014
Not 100% sure but I'm pretty sure your oil pan won't clear technically in the exact factory position unless you notch your k member. It's all relative but since it looks like you have your k member out I'd suggest putting it on out of the car and see how you like the clearance. Your mounts have enough leeway to either not clear the kmember or for the drivers side head to hit the firewall, and I know that doesn't help you much.
All information helps at this point. Its like the calm before the storm.. Yea I did plan to put the engine on the k member to see if it clears or not... but I'm ok with notching it to make oil pan clear especially if I'm going to need a custom driveshaft
Unless I missed something up above you shouldn't need a custom drive shaft. I didn't notch my k member and the driveshaft is almost too long but it's perfect. So you can either keep your stock one or get a new one and stock should be fine. I got this one from summit. I have a 9" rear so I just used a different u joint but the way it comes should bolt right up to a 10 bolt.
Unless I missed something up above you shouldn't need a custom drive shaft. I didn't notch my k member and the driveshaft is almost too long but it's perfect. So you can either keep your stock one or get a new one and stock should be fine. I got this one from summit. I have a 9" rear so I just used a different u joint but the way it comes should bolt right up to a 10 bolt.
Ok, we'll find out after New Years but it's time for the engine/transmission to go in now before I put the front suspension on... I keep trying to upload pics but this site uploader is acting fruity
Got some goodies in... and this is how my motor mounts are set up on k member. I will have to find out the correct orientation... hopefully I can get it right the first time
The holes were already there from when I previously had the 95 lt1 engine in the car
There’s definitely no need to notch the k member for an ls1 (f body) pan and the factory driveshaft worked fine for my swap which was factory auto/v8.
You will I’ll need to notch if you want to run a low mount a/c. I would think there would be instructions on which holes are for a 1” set back.
Yea I definitely have a factory ls1 fbody oil pan, I plan to relocate my a c compressor to the top when I'm ready for it as I dont have one yet to install..
The plates came with no instructions but it just says it's a 4 position plate..
This is what I came up with. I read that you slide the clamshells all the way to the front holes and bolt them in. Can someone confirm this for the factory location sbc to reuse factory driveshaft and mount 4l60e in factory location.. Im trying to do this one time hopefully.
I did grind the indention on the clamshells flat to make them sit flush on adapter plates.. My sbc motor mounts are located in the factory position
Take your k member while it's out and mount it to the engine out of the car. You might want to hit the back welds in a little for more clearance. Give yourself like 3/8 inch clearance from the back of the k member to the front of the pan. I'd estimate that any more than 1 inch clearance without notching k member will leave your stock driveshaft too long (with a t56). I think the 4l60 tail shaft mounts in the same location. Someone will have to help me out on this because I'm not positive.
But you can use your k member to your advantage with it out of the car by mounting it to the engine to provide the exact clearance you want with the fbody pan.
Take your k member while it's out and mount it to the engine out of the car. You might want to hit the back welds in a little for more clearance. Give yourself like 3/8 inch clearance from the back of the k member to the front of the pan. I'd estimate that any more than 1 inch clearance without notching k member will leave your stock driveshaft too long (with a t56). I think the 4l60 tail shaft mounts in the same location. Someone will have to help me out on this because I'm not positive.
But you can use your k member to your advantage with it out of the car by mounting it to the engine to provide the exact clearance you want with the fbody pan.
It's close. Your driver's side head might be a little close to your firewall so if you have some leeway with the brackets you can get it closer. Mine has roughly half that much clearance.
It's close. Your driver's side head might be a little close to your firewall so if you have some leeway with the brackets you can get it closer. Mine has roughly half that much clearance.
We slided the motor one position forward . Hows that Headers not much clearance with kframe but its not touching
That looks pretty good to me. Pictures are always tougher to say for sure but that looks about like mine. That is the same amount of clearance I have for my speed engineering headers. What crossmember are you planning on using for the 4l60?
That looks pretty good to me. Pictures are always tougher to say for sure but that looks about like mine. That is the same amount of clearance I have for my speed engineering headers. What crossmember are you planning on using for the 4l60?
We are going to install it today from the bottom with transmission attach. I'll see how the trans crossmember looks.. at worse my friend will modify it. Cut it up and add 2 4inch round metal pieces with torque arm bracket so when they run exhaust, I'll have more ground clearance... looks good though so far
I’m gonna say your second pic is correct. I just crawled under my car as best as I could without jacking and I can’t get a finger between the k member and oil pan.
Looks good man! Best of luck. It's really satisfying once you see it all bolted.
Originally Posted by Billgluckman
I’m gonna say your second pic is correct. I just crawled under my car as best as I could without jacking and I can’t get a finger between the k member and oil pan.
Thanks for all you guys help this far. We are about to go in with the engine she's ready
We got it all in. Driveshaft fit in factory location, trans crossmember will need to be modified as expected. K member lined up.. feel pretty good.. but I think it's called HVAC heater box or something by #8 coil.. I didnt catch it and it broke a piece of the box.. what is this thing called? And how much does it cost? Pic below We're bolted in!
It's the evaporator case. I broke part of mine as well but it's really just there to protect the ac evaporator. Honestly I just put some gorilla tape over it and called it good and it's fine. Looks fine too because the heater houses cover it up anyway.
Nice pics! Looks like it is really coming together for you.
Isn’t is fiberglass? I’m not in front of one right now but it may be repairable. If it is, fiberglass is easy enough to work with.
I forgot to tell you about that coil though. I chopped the back of the coil bracket off and welded it back on but I offset it away from the box. I’m sure there’s also an aftermarket solution as well.
Isn’t is fiberglass? I’m not in front of one right now but it may be repairable. If it is, fiberglass is easy enough to work with.
Mine is definitely plastic on my 91. But in the pics it looks like fiberglass now that I look again. Maybe mine was a reproduction it something. I have a white styrofoam lining inside mine.
Mine is definitely plastic on my 91. But in the pics it looks like fiberglass now that I look again. Maybe mine was a reproduction it something. I have a white styrofoam lining inside mine.
Ill look at mine later and see but I think it’s fiberglass.
I’d also check local junk yards because I can’t see this being expensive. The problem is, in my area anyway, third gens are getting scarce. Be aware it’s gonna be a tight fit get fit getting it out and back in with the ls in place but it’s doable, I think I had to remove the blower first though.
It's the evaporator case. I broke part of mine as well but it's really just there to protect the ac evaporator. Honestly I just put some gorilla tape over it and called it good and it's fine. Looks fine too because the heater houses cover it up anyway.
Nice pics! Looks like it is really coming together for you.
Originally Posted by Billgluckman
Isn’t is fiberglass? I’m not in front of one right now but it may be repairable. If it is, fiberglass is easy enough to work with.
I forgot to tell you about that coil though. I chopped the back of the coil bracket off and welded it back on but I offset it away from the box. I’m sure there’s also an aftermarket solution as well.
Originally Posted by cmiller2014
Mine is definitely plastic on my 91. But in the pics it looks like fiberglass now that I look again. Maybe mine was a reproduction it something. I have a white styrofoam lining inside mine.
Yea, mine is definitely fiberglass, I'll see what I can do with it.. Yea, @Billgluckman
I think I read your thread or somewhere about #8 coil and that box interference.. I just forgot about it.. I'll deal with it eventually... Now putting back the suspension parts. I dropped my Aframes off to my buddy house so he can press the old ones out, and press new ones in.. everything else is new except the pitman arm to the gear box thing bracket... My trans crossmember, I want to do this with it like this guy did for his swap to give me more clearance for exhaust running..
12-04-2019, 01:52 PM
