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CMQuickcoupe, the Energy Suspension 3.1142 transmission mount has a 3/8" lower height than than the 3.1108 mount you currently have. The Prothane mount height is in-between those two.
Is there any other shorter mount that can be used? from what ive seen i dont think 3/8 of an inch is gonna let it fit in there. how much room would there normally be between the trans and tunnel?
Is there any other shorter mount that can be used? from what ive seen i dont think 3/8 of an inch is gonna let it fit in there. how much room would there normally be between the trans and tunnel?
If you are experiencing that level of interference, we need to back up and verify a couple of things. Let's start with the specific model of A-body you are working on and then validate that your engine brackets are as they should be...do your engine brackets look like these in the attached image?
Im working on a 69 chevelle and yes my mounts are the forward biased just like in the pic you have,holley 302-2 pan just clears the rear of the cross member. If i top the trans out in the tunnel and put your crossmember in on the driverside and try to mount it up on the passenger side the humps of the crossmember are hitting the floor and it only leaves 1-1/8 gap for a trans mount to sit on top of the center of the cross member.
OK, that confirms for me that you indeed have the correct crossmember. From what I've seen, there are two possible causes of the non-fitment you're experiencing and those would be the crossmember being manufactured outside design tolerances, or the floor sag I mentioned previously.
Validating the crossmember is easier, so we'll start there in the morning by me giving you a couple of reference points to measure the crossmember off of a flat surface you might have available.
In the meantime you might want to look for and review a build thread on this forum for member korndawg as he's installed the same engine/trans combo as you in his Chevelle (1970 year model I believe) using the Hooker system of parts with zero issues, so there may be something you can glean from his installation that would shed light onto your situation.
I'll post up again in the morning from the office.
I"ll check out his thread,I dont think theres any way its floor sag as the underside of this car is near perfect and as i mentioned there is only 1 1/8 inch of space between the trans which is topped out in the tunnel and the cross member where its at,for the mount you mentioned to even come close to fitting the trans would have to go up another inch almost that way it could come down off the tunnel roof a bit when its bolted to the cross member so i would kinda rule out floor sag of that magnitude
Also i cant even get the stock cross member to fit in stock position muchless with the spacers that come with the forward biased engine mounts i have. This trans just seems to big for the factory tunnel.
CMQuickcoupe, is your car an original manual transmission car, or automatic car? I've been doing some checking with member korndawg and his car was an automatic car originally and he told me he can get a finger in-between his floor and 4L80 even at the tightest areas, which is indicative of the clearance obtained in the development mock-up.
CMQuickcoupe, is your car an original manual transmission car, or automatic car? I've been doing some checking with member korndawg and his car was an automatic car originally and he told me he can get a finger in-between his floor and 4L80 even at the tightest areas, which is indicative of the clearance obtained in the development mock-up.
Correct. No issues at all with my 4L80e in my automatic car.
Mine is original auto car,with the trans topped out in the tunnel there is only 1 1/8 inch gap between the trans mount pad on the tail shaft and the top of the cross member. Mine seems like it is hitting on the top front where the bell housing tapers down and the case starts close to where the vent is
Mine is original auto car,with the trans topped out in the tunnel there is only 1 1/8 inch gap between the trans mount pad on the tail shaft and the top of the cross member. Mine seems like it is hitting on the top front where the bell housing tapers down and the case starts close to where the vent is
Could the body mount cushions/rubbers be worn out or replaced with the wrong ones and the body is sitting lower to the frame than stock?
See if you can get the crossmember on a flat table and check the dimension called out in the snippet of the drawing of the crossmember I've attached here. With the bottom of the center part of the crossmember sitting on the table, measure the distance between the table and the underside of the welded-on foot bracket. It should measure close to the 1.66" shown.
If you are experiencing the interference up around the bellhousing area that is typically happens when using the rear-bias engine brackets with a 4L80 installation. Are you sure your engine brackets don't look like these?
Im positive my engine brackets dont look like those, they are the forward biased engine brackets with 4th gen motor mounts. I measured the cross member and it matches the specs you have in your pic. Best i can tell the interference starts at the base of the bell housing about where the vent tube is placed, then it looks clear to the back and the next place it will make contact is a boss on the passenger side close to the tailshaft if the trans went any higher which it wont. What should the trans angle be i might have to modify my original cross member and send this one back.
I'm very curious to know what the fundamental difference between the floor of your car and the floors of many others who have used the same Hooker parts without issue. Unfortunately, I think we've exhausted the checks that can be done through the exchange design dimensions and pictures.
If you want to use the stock crossmember and install the transmission at the inclination angle it is at without modifying/cutting the floor, the only option you have to obtain optimized U-joint working angles is to run a CV driveshaft. My guess is your engine inclination angle were it's at now is around 4-6 degrees relative to the bottom of the frame, which will not equate to satisfactory U-joint operating angles, especially if your car is lowered in the rear.
10-15-2017, 07:13 PM
