Diagnosing/Fixing drivetrain looseness/play
08-16-2021, 07:43 PM
#1
Junior Member
Thread Starter
Join Date: Jan 2019
Location: GA
Posts: 106
Total Cats: 4
Diagnosing/Fixing drivetrain looseness/play
So I've got my VVT swapped NA driving like I want it to for the most part, except I think I've got some play in my rear diff, or maybe an axle. How would I go about diagnosing/fixing this?
My drivetrain:
VVT engine - MS3 PnP
6 speed transmission - when I bought this component, I moved the input shaft myself and saw no play between it and the output shaft regardless of gear. Installed with diff and axles at the same time.
3.63 Torsen 2 diff - bought here from a UK distributor. I did not inspect this part myself prior to putting it in, but had my local shop put it in for me. They replaced the seals prior to putting it in. Installed with trans and axles at the same time
1.8 driveshaft and axles - bought with the diff. Installed with trans and diff at the same time.
The symptom:
When I'm driving and I go from acceleration to suddenly letting completely off the gas, the car will jerk/shudder a small bit. Also, when the car is in gear but no throttle (engine braking), and I apply the throttle, the car will jerk/shudder even though my AFMs don't show anything scary. This was very simlar to when I had my old 5 speed that I felt I had to baby, and when I took that out and put in the 6 speed, I noticed there was several degrees of play between the input and output shaft. This also means that there has always been this problem with the car, and my dad (the prior owner) even said this felt "normal" to him, but again the old transmission had play in it, and this doesn't feel "normal" to me. It makes me be very, very careful when powering out of a turn, because I have to apply throttle oh so gently or else the car will shudder.
Any ideas?
My drivetrain:
VVT engine - MS3 PnP
6 speed transmission - when I bought this component, I moved the input shaft myself and saw no play between it and the output shaft regardless of gear. Installed with diff and axles at the same time.
3.63 Torsen 2 diff - bought here from a UK distributor. I did not inspect this part myself prior to putting it in, but had my local shop put it in for me. They replaced the seals prior to putting it in. Installed with trans and axles at the same time
1.8 driveshaft and axles - bought with the diff. Installed with trans and diff at the same time.
The symptom:
When I'm driving and I go from acceleration to suddenly letting completely off the gas, the car will jerk/shudder a small bit. Also, when the car is in gear but no throttle (engine braking), and I apply the throttle, the car will jerk/shudder even though my AFMs don't show anything scary. This was very simlar to when I had my old 5 speed that I felt I had to baby, and when I took that out and put in the 6 speed, I noticed there was several degrees of play between the input and output shaft. This also means that there has always been this problem with the car, and my dad (the prior owner) even said this felt "normal" to him, but again the old transmission had play in it, and this doesn't feel "normal" to me. It makes me be very, very careful when powering out of a turn, because I have to apply throttle oh so gently or else the car will shudder.
Any ideas?
Reply
0
0
08-17-2021, 09:35 AM
#4
Junior Member
Join Date: Mar 2015
Posts: 287
Total Cats: 33
Check engine mounts, perhaps bolt torque if they've been replaced - sounds like the most likely culprit.
You also want to check PPF bolt torque, and check your diff mounts as well. The whole drivetrain kind bolts together so play in any of those items could cause that behavior.
If you've not checked your PPF alignment - you may wish to do so as well.
You also want to check PPF bolt torque, and check your diff mounts as well. The whole drivetrain kind bolts together so play in any of those items could cause that behavior.
If you've not checked your PPF alignment - you may wish to do so as well.
Reply
0
0
08-17-2021, 10:13 AM
#5
Junior Member
Thread Starter
Join Date: Jan 2019
Location: GA
Posts: 106
Total Cats: 4
So earlier, the reason I wasn't driving the car was because of a fueling issue. Turned out it was 2 bad sending units, specifically the wiring. The one that was in the car, and the one I got to replace it. When my local shop replaced it with their own sending unit, I also asked them about this question. They took a look and tightened all the PFF/diff bolts and everything.
How would I verify their work? Just get underneath the car with a wrench and see if anything is loose?
How would I verify their work? Just get underneath the car with a wrench and see if anything is loose?
Reply
0
0
08-17-2021, 10:41 AM
#6
Cpt. Slow
iTrader: (25)
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 14,203
Total Cats: 1,138
They’re upside down bolts, they’ll fall out if they’re loose. Torque for the big ppf bolts is 90 ft/lbs, same as your wheel lugs, so if you have a torque wrench for those, it’ll work with a 17mm socket. The 4 longer ones take a lot of stretch before they reach 90, so it turns more than you think before clicking.
You might try looking into your AE settings, they can cause jerkiness if not tuned well.
but to check play, grab the driveshaft and rock it back and forth by hand very slightly. You’re looking for The driveshaft to move when the axles aren’t. That’s play in the ring gear, a little is normal. Check the axles too, there shouldn’t be any rotational play in them.
You might try looking into your AE settings, they can cause jerkiness if not tuned well.
but to check play, grab the driveshaft and rock it back and forth by hand very slightly. You’re looking for The driveshaft to move when the axles aren’t. That’s play in the ring gear, a little is normal. Check the axles too, there shouldn’t be any rotational play in them.
Reply
0
0
08-17-2021, 10:47 AM
#7
Junior Member
Thread Starter
Join Date: Jan 2019
Location: GA
Posts: 106
Total Cats: 4
They’re upside down bolts, they’ll fall out if they’re loose. Torque for the big ppf bolts is 90 ft/lbs, same as your wheel lugs, so if you have a torque wrench for those, it’ll work with a 17mm socket. The 4 longer ones take a lot of stretch before they reach 90, so it turns more than you think before clicking.
You might try looking into your AE settings, they can cause jerkiness if not tuned well.
but to check play, grab the driveshaft and rock it back and forth by hand very slightly. You’re looking for The driveshaft to move when the axles aren’t. That’s play in the ring gear, a little is normal. Check the axles too, there shouldn’t be any rotational play in them.
You might try looking into your AE settings, they can cause jerkiness if not tuned well.
but to check play, grab the driveshaft and rock it back and forth by hand very slightly. You’re looking for The driveshaft to move when the axles aren’t. That’s play in the ring gear, a little is normal. Check the axles too, there shouldn’t be any rotational play in them.
How much play in my diff is normal? Last time I was underneath the car, I checked driveshaft versus axles for play and got some. It's hard to say how much since I don't exactly have a protractor or anything under there, but it was a good bit of wiggling the driveshaft with zero result on the axles. Maybe as much as 5-10 degrees, but that could be wrong. That's why my first thought was differential.
Reply
0
0
Thread
Thread Starter
Forum
Replies
Last Post
ehodder
Suspension, Brakes, Drivetrain
7
03-03-2022 09:44 AM
