Gun Jam

I had been running the Ron Morris performance lowered motor mounts that I had actually shimmed up about .25 to .38" because as they came they were so low that the drag link would just touch the oil pan.

I have a t5 transmission

In the near future I am planning Rack and Pinion upgrade (TCP) and a requirement is stock height motor mounts. I bought the stock height RMP plates and replaced the lowering plates so the engine is now back to stock height (Per RMP specs..I would guess they did the measuring) This raised the engine about .5" from where it had been for the last few years.

at 70mph I get noticeable vibration its worse at 80 and gets worse when I let off and let the car coast down from 80. DS RPM should be 4100 at 80 with 3:80 rear end and 25" tall tire (stock DS)

There is noticeable play in the slip yoke and trans side U-joint not a ton but you can see it. (this will be fixed here soon but until I moved the engine it had been working well like this)

I have some fancy tools now to better deal with the measurements and improved skill set from when I last did this.

Measurements were collected with suspension loaded car very close to level and base of rocker panel used as 0deg reference point. (you know the thing below the door that is welded floor pans and has that seam that hangs down....the bottom that faces the road is very flat and long thats where I set the level) A digital level was used it indicates if a slope is up or down and allows a reference offset to be used.

1) I placed level on bottom of rocker panel it was 0.30 deg off of level. The level was then referenced to this angle and now reads 0.0

2) placed level on slip yoke bearing cap (same as transmission angle) 4.2 deg down

3) placed level on DS tube 0.8 up

4) placed level on pinion yoke bearing cap (same as pinion shaft angle) 1.3 deg up (has what looks like 2.5 deg wedges installed under leaf spring thick end towards front of car which would force pinion yoke upwards towards floor pan.

Line slope up or down as I see it is 1 based off of what the level says and 2 if you were to walk from the front of the car towards the back and the slope is down then you would be walking down hill if the slope is up when you would be walking up hill.

Here is a cool picture of what I'm talking about.



Does anyone know what these angles should read? I remember that trans angle should be 3.0 deg down (mine is excessive here and was made worse by the increased motor mount height. What was stock pinion angle?

Now if you read about how they should look you get two answers:
1) if your trans slopes down 3 deg your pinion should be the same ( simply drawn as two parallel lines. That would mean the tail shaft would point down (you walk down hill from the front of the engine) and the pinion yoke would point up towards the floor pan 3 deg even though the yoke points up on the pinion the line is down because when walk from front to back you would be walking down hill once you reached the pinion line) they look like this ( \ \ ) parallel

2) the other idea is if the trans is down 3 deg the pinion yoke should point down at the ground 3 deg (an up hill slope) they would look like this (\ /) an intersecting set of lines this is to accommodate for axle wrap so under load the lines would be parallel as the pinion twist up towards the floor pans under load.

That said I dont think either of those will help me and I dont think shims will fix anything (I have some I can try or re arrange) I think the issue is the 5.0 deg operating angle. Because of this it would appear that the only solution is to cut the trans tunnel open to allow that ridge on the t5 where the shift rod slides to move up. because right now I have about 1/8" of clearance between it and that brace thing inside the tunnel.

I was thinking of cutting that brace thing in half with about a 1" wide notch so I could move the tail shaft up about 1"

But before I cut stuff up based on what we know now any ideas?

Thanks

-Gun

69mach1377

I recall your other thread on this and after messing around with pinion angle I just bought a Denny's 3.5 alum shaft, converted to 1350 joints front and back and put in a new tailshaft bushing. The bad vibes at 80+ went away and I'm so glad I didn't have to cut up my trans tunnel.
Unfortunately, my supposedly badass Gforce T5 broke 3rd gear and burnt up the mainshaft pilot to the input. What a POS!

Gun Jam

do you have a 9" rear end? Is there a pinion yoke that will accept 3 5/8" between bearing caps and fit an 8"?

Thanks

-Gun

69mach1377

Yes I do. Not sure about the yoke, how many splines does the 8" have?

barnett468

.

try a wedge on the rear axle to raise the pinion 2 degrees

Gun Jam

by this you mean that the wedge would force the pinion yoke up towards the floor pan? so my net gain would go from 1.3 up to 0.7 down?

The problem with reading about this stuff online is I can not tell if they are talking about slope or simply whether or not the pinion yoke points up at the floor pan or down at the ground. (the two are opposite...a positive slope causes the pinion to point down at the ground)

Thanks

-Gun

barnett468

the pinion and the trans angle should be the same while driving . . the pinion will rise some when under load while driving on the highway so start it around 1 degree less than the trans.

or cut a big hole in your floor.

watch this

racer_dave

As soon as I saw this thread I started searching my computer for a video I have saved - and lo and behold barnett468 posts it.

Gun Jam

Yeah its good stuff I have watched many of them.... but in leaf spring applications it seems the general idea is the pinion yoke should point at the ground about 2 deg...so both the trans yoke and pinion yoke should point at the ground.

Im am fairly certain at this point my main issue is worn U joints....I have a new Dennys Al driveshaft on the way....Once thats installed I'll be able to make a better assessment of the situation. Its time a for an upgraded DS anyhow so its good either way.

Thanks

-Gun

69mach1377

I hope the new DS fixes it as it did in my case. Don't forget a new bushing also.