Pinion Angle, Driveshaft angle, lowering the car.
#1
Pinion Angle, Driveshaft angle, lowering the car.
OK, I have searched but I can't find a post with similar issues so here goes..
I have an 88 IROC conv. with a Moser 9", a Tremec TKO, Spohn suspension stuff, etc.. When I first started on the car I installed a set of Eibach pros but didn't like the stance (the rear was too high) so I cut a coil out of the rears to set the car where I liked it. At that time I set the pinion angle at -1
but incorrectly as I measured the pinion against the driveshaft. Most recently I set the pinion at -1 against the crankshaft - this resulted in a big vibration at about 70 mph that continued (and got worse) when I put the trans in neutral. I figured that since I had recently installed the Moser that the car was severely out of alignment - not the case. What I did have was
extreme working angles on the driveshaft - 6 deg. in front and 5 deg in the rear. In addition, my driveshaft points UP from the trans tailshaft to the rear pinion. If I adjust the pinion to -5, I get driveshaft working angles of 2.5 and 1.5 front to rear. The vibration is greatly reduced.
I want to keep the stance - it looks great, so putting stock springs in the rear is not an option. I autoX the car and it handles like a go-kart. Shimming the rear of the trans up 1" at the rear mount is attractive but not currently possible in that the TKO has the large mounts for putting the shifter in the different positions. My plan is to modify the trans tunnel when I install the roll bar this winter. I will cut the necessary clearance in the trans tunnel and then reweld "a cap" - it should be invisible.
Has anyone else run into this problem? I want to avoid shooting myself in the foot as I only have a few toes left.
I have an 88 IROC conv. with a Moser 9", a Tremec TKO, Spohn suspension stuff, etc.. When I first started on the car I installed a set of Eibach pros but didn't like the stance (the rear was too high) so I cut a coil out of the rears to set the car where I liked it. At that time I set the pinion angle at -1
but incorrectly as I measured the pinion against the driveshaft. Most recently I set the pinion at -1 against the crankshaft - this resulted in a big vibration at about 70 mph that continued (and got worse) when I put the trans in neutral. I figured that since I had recently installed the Moser that the car was severely out of alignment - not the case. What I did have was
extreme working angles on the driveshaft - 6 deg. in front and 5 deg in the rear. In addition, my driveshaft points UP from the trans tailshaft to the rear pinion. If I adjust the pinion to -5, I get driveshaft working angles of 2.5 and 1.5 front to rear. The vibration is greatly reduced.
I want to keep the stance - it looks great, so putting stock springs in the rear is not an option. I autoX the car and it handles like a go-kart. Shimming the rear of the trans up 1" at the rear mount is attractive but not currently possible in that the TKO has the large mounts for putting the shifter in the different positions. My plan is to modify the trans tunnel when I install the roll bar this winter. I will cut the necessary clearance in the trans tunnel and then reweld "a cap" - it should be invisible.
Has anyone else run into this problem? I want to avoid shooting myself in the foot as I only have a few toes left.
#2
Supreme Member
iTrader: (15)
Join Date: Aug 2006
Location: Central NJ
Posts: 12,665
Likes: 0
Received 50 Likes
on
48 Posts
Car: 86 Trans Am, 92 Firebird
Engine: 408 sbc, 3.1L of raw power
Transmission: TKO600, T5
Axle/Gears: Moser 9", 3:70 trutac, 3:23 torsion
Re: Pinion Angle, Driveshaft angle, lowering the car.
ive got a similar setup and ive noticed the same thing, the trans is just very tall and the tunnel is not high enough to get the propper angles with a lowered car, tunnel mods would probably help, but if you are using the stock center console i think it could cause issues
#3
Re: Pinion Angle, Driveshaft angle, lowering the car.
Thanks. I'll be doing this in a month or two, I really want the correct angles. I'm running fairly stiff suspension members and I really feel the driveshaft vibrations. I'll post pictures when I get into it.
Thread
Thread Starter
Forum
Replies
Last Post
ambainb
Camaros for Sale
11
04-25-2016 09:21 PM
lt1z350
Engine/Drivetrain/Suspension Parts for Sale
3
09-29-2015 01:50 PM
Linson
Auto Detailing and Appearance
40
08-21-2015 02:12 PM