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RSJ78, I'm posting this photo for you so you can use it as a reference to judge the clearance and position of your 4L60 trans and your floor. Dose the step in your floor appear to be in the same proximity to the extension housing flange/bolts on your trans as it does here in this photo?
Just in case my post with other pics doesn't come here they are. I grabbed a high hump tunnel and extension to replace mine if nothing else works.
I was using a Energy Suspension 31108 mount but just got the recommended Prothane model today. All the cab mounts have been replaced with new rubber from LMC, but I reordered a the front set since tube was screwed up. The yellow floor is what the 80's 2wd look like from what I can tell.
I appreciate you posting the photos of the difference in the floor contours, it's not something I was aware of previously and will need to perform some instruction/web listing edits to address it. I have a 79 square-body and just confirmed that the floor in it is like yours, so I assume the change happened with the rest of the cab changes for the 81 model year.
I can't tell if your trans is resting on the mount or not, but if it is, it seems like the use of the low height poly mount that Energy Suspension offers will get you the clearance you need between the trans and the floor. The part number for that mount escapes me at the moment, but I do have it at work if you need it...it's about 3/8" lower in height than the standard Energy Suspension mount you listed.
Short of modifying the floor, I would install the lower height ES mount and then shim it as needed to get the trans about 3/16" from the floor.
I will take another pic tomorrow if it help!
Sure if you can get me that part number when you get a chance I will definitely try it before I cut into anything.
Do you think there will be any negative effect with angles with that bushing?
Thx, Scott
I don't think you'll have any issues using the lower mount, especially if you take the time to shim it up to get the trans/driveshaft as high as you comfortably can.
Prothane mount gave me a tiny bit of space.....enough to get a thin piece of cardboard.
That's good news and means you won't have to deviate much from the designed geometry of the system if you swap to the lower height Energy Suspension mount and shim it to end up with another 1/8" or so clearance than you have now with the Prothane mount.
Yeah I got it ordered so I'll see and post results.
I may still install the 4x4 higher hump to give the trans more room to breathe and any unforeseen issues down the road like cab mount settlement and if I upgrade to a 4L80 later.....I want to make sure I got everything covered before removing again for paint.
Well I got the shorter height ES bushing installed this morning and have almost exactly 3/16".....so you were dead on Todd!
So do you think 3/16" is enough room to not have any hitting of the trans to the floor pan during driving conditions? Mind you I did install new rubber cab mounts.
Todd, do you have any crossmembers that can be used with a 6L90e trans.
I see the 4L60's are a tight fit by the pics posted. THANKS
The 6L80/6L90 transmissions were not accounted for in the development of the Hooker GM Squarebody truck LS swap system, so I have no idea whether the Hooker transmission crossmember, and possibly the T56 adapter bracket, can be utilized to install either of those transmissions.
This is an image of the e-brake cable and the Hooker transmission crossmember and exhaust system on my 79' C20, which is not an LS swap. The cable routing was left as is was configured by the PO to accomodate the no-name SB Chevy Tri-Y headers and pieced-together exhaust that were on the truck when I acquired it. The headers are still the same ones and I intend to reconfigure the e-brake cable and rods one I build some new headers for the truck.
Hi Toddoky,
I just found this thread... earlier in it, I saw the photos of the red c10 with all the Holley goodies... what engine harness was on the truck? And was the ecm/tcm hidden under the dash? Super clean setup, and is what I am looking for!
-Clint
07-11-2017, 07:32 PM
