barnett468

well it is the relationship of the driveshaft to the pinion AND the trans.

when people jack their vehicles up 24" they must change the pinion and TRANS ANGLE BUT VERY FEW KNOW ABOUT CHANGING THE TRANS BECAUSE ALL THEY HEAR or read about is the pinion angle.

your pinion can be 20 degrees up from horizontal as long as the driveshaft it up 4 - 5 degrees farther than that from the pinion and down around he same amount down from the trans.

you must measure the pinion and the driveshaft,. the differebce should be 4 - 5 degrees.

if your driveshaft comes straight out of either your trans or pinion with NO angle in it, it will likely vibrate.

you need a cheap angle finder/inclinometer from home depot.

.

barnett468

actually this not quite how its done.

if the trans and pinion are horizontal and on the same plane/elevation, there will be no angle in the driveshaft.

if you raise the entire trans or lower the entire pinion, they will both still be horizontal but an different planes/elevations which will cause the driveshaft to be at an angle relative to them.

3 degrees is not enough because the rear end has travel in the suspension. if you load it up with people and a few cases of beer in the trunk your driveshaft will be below the magical 2.5 degree angle relative to the trans and diff which may cause vibration.

69mach1377

My pinion is pretty much inline with the DS, so I will remove the wedge to bring it down 2*. My trans is down 2.2* compared to the DS. The angle finder did not help much, so I used plumb bobs and length and height measurements and trig to figure out the angles. I still don't like that the angles will not be opposite/parallel even though they will be nearly equal. I would have to raise the back of the trans a lot to get them parallel...

barnett468

not nearly enough but if thats all you got at the moment, it's all you can do.



how did this happen?

this should definitely have a vibration in it.

your trans needs to come up 6.2 degrees or at least 4.2 so it will then match your new 2 degree shaft relationship to the pinion.



sorry but i have no idea what you are talking about. please read my posts again, the correct info is there. unfortunately i can not explain it any better.

69mach1377

Ever notice factory intakes have a 2-3* angle for the carb base? This is keep the carb level while the back of the engine/tranny angle down by that amount. Are you saying engines usually tip forward from the factory?
As for your last comment, 1 pic = 1k words, but I think we are on the same page...

barnett468

hello;

no that's not what i am saying. as i mentioned i can nit explain the relationship of the driveshaft to the trans any better than i have. i am simply incapable of it. perhaps someone else can but the correct driveshaft angle is in my posts.


you have a driveshaft the runs uphill from both the trans and the pinion. this is messed up. i have no idea how it could have gotten this way unless the engine is at the wrong angle because the rear end would have to be lowered all the way with 0 suspension left to get the driveshaft anywhere near or past horizontal on the trans.

unfortunately, something is seriously wrong with your car.

if you have an engine that angles down in the rear by say 3 degrees, the driveshaft MUST angle down from the engine by 4 ro 5 degrees which creates the following:

engine from horizontal = 3 degrees

driveshaft from horizontal = 7 - 8 degrees.

all you need to do is follow the numbers to fix your car.

i wish i could help you more but i doubt that i can.

.
ok, this is photo shows what is a grossly incorrect pinion to driveshaft angle because the driveshaft is running downhill from the pinion. the nose of the pinion should be pointing down enough so the driveshaft runs uphill from the pinion.





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69mach1377

Well I can reverse the wedge to get the pinion down 4*...

barnett468

this will not properly cure your prob at the trans though because your shaft will still not run downhill from it.

i notice you are not mentioning how your driveshaft ended up running uphill from the trans or why you need a wedge on the differential and i think i am afraid to know, lol.

it has been purported that you can run the shaft uphill from both the trans and pinion at the same time or vise versa, but this is only on a vehicle that has little to no suspension travel though, but that is not a theory i care to test.

69mach1377

T5 swap is all I can say...I guess the swap crossmember is to blame?

barnett468

well there are a dozen different mfg's of those cross members these days and of course some are not us made. either way, the top of your trans at the shifter is flat and square and the outer edges of that square should be around 1/4" - 3/8" from the body. it should almost be touching. if it is like an inch or more, your bracket is inaccurate.