HARD Vibration on Deceleration
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From: Riverside
HARD Vibration on Deceleration
I have 1998 Ls400 and recently I noticed my welded diff broke so I got a new one and got it welded , put it in yesterday and while the diff worked perfect , I started noticing a weird vibration towards the back of the car on bumpier parts of the road
I pulled over and looked under the car everything seemed good but on my drive home it was progressively worsening,
when I decelerate anywhere now i get a real crazy vibration from the back almost like a knocking or banging , it’s perfect when I’m on the throttle anything more than 5% but braking or off throttle its there.
i even went ahead and replaced the rear axles thinking it was those but the problem is still the same
it’s noticeable when car is jacked up and in drive, and when coasting being in drive/neutral and braking or not
I pulled over and looked under the car everything seemed good but on my drive home it was progressively worsening,
when I decelerate anywhere now i get a real crazy vibration from the back almost like a knocking or banging , it’s perfect when I’m on the throttle anything more than 5% but braking or off throttle its there.
i even went ahead and replaced the rear axles thinking it was those but the problem is still the same
it’s noticeable when car is jacked up and in drive, and when coasting being in drive/neutral and braking or not
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Joined: Oct 2019
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From: Florida
I have 1998 Ls400 and recently I noticed my welded diff broke so I got a new one and got it welded , put it in yesterday and while the diff worked perfect , I started noticing a weird vibration towards the back of the car on bumpier parts of the road
I pulled over and looked under the car everything seemed good but on my drive home it was progressively worsening,
when I decelerate anywhere now i get a real crazy vibration from the back almost like a knocking or banging , it’s perfect when I’m on the throttle anything more than 5% but braking or off throttle its there.
i even went ahead and replaced the rear axles thinking it was those but the problem is still the same
it’s noticeable when car is jacked up and in drive, and when coasting being in drive/neutral and braking or not
I pulled over and looked under the car everything seemed good but on my drive home it was progressively worsening,
when I decelerate anywhere now i get a real crazy vibration from the back almost like a knocking or banging , it’s perfect when I’m on the throttle anything more than 5% but braking or off throttle its there.
i even went ahead and replaced the rear axles thinking it was those but the problem is still the same
it’s noticeable when car is jacked up and in drive, and when coasting being in drive/neutral and braking or not
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 21
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From: Riverside
it would make sense but the previous diff was welded and never had an issue like this, I know a few dudes local to me as well with welded diffs in their LS and from what I told them they told me it was an axle issue, so I changed axles and no change
Thread Starter
Driver School Candidate
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From: Riverside
Racer
Joined: Mar 2018
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From: Nevada
I hate to be that guy, but this is kind of what you get for welding the differential. It's a cascading waterfall of problems. Based on your other posts you're tracking the car so I get it, it's the cost of doing business. But I'm surprised traction is enough of a problem to have the solution be a welded differential. It's not like this car has 600 horsepower and it's struggling to put it's power down in third.
It's probably as simple as: this time, the weight of the metal added during the weld was unbalanced which now causes issues, when last time, it was better balanced. Or it could be the driveline shock of driving around with a welded differential causing damage to your drifeshaft or flex disc. There could be damage on the transmission end of the driveshaft, not just at the differential end. How much driveshaft rotational play is there with the car in the air? That's probably where the vibration is.
It's probably as simple as: this time, the weight of the metal added during the weld was unbalanced which now causes issues, when last time, it was better balanced. Or it could be the driveline shock of driving around with a welded differential causing damage to your drifeshaft or flex disc. There could be damage on the transmission end of the driveshaft, not just at the differential end. How much driveshaft rotational play is there with the car in the air? That's probably where the vibration is.
Last edited by 400fanboy; May 14, 2023 at 06:09 PM.
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Joined: Jul 2019
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From: CA
Either there is an issue with the installing of the differential, is it installed correctly and is it the right differential? Where did you get the replacement differential? If you didn't test the differential before the welding procedure you won't for sure if it was a good one or the right one. And who did the welding? It heats the heck out of it because of the heat from welding and that may or may cause a problem. You want to let them self cool after welding too. Sounds like the gears are binding, or some kind of an alignment issue. Just a matter of figuring out why, and what it is. It's already welded so now its just a process of elimination which might mean you will need to buy another differential that is not welded, install it, and see if the problem goes away.
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Advanced
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From: CA
I hate to be that guy, but this is kind of what you get for welding the differential. It's a cascading waterfall of problems. If the purpose of the car is to drift, then that's fine. Based on your other posts you're tracking the car so I get it. But I'm surprised traction is enough of a problem to have the solution be a welded differential. It's not like this car has 500 horsepower and it's struggling to put it's power down in third.
It's probably as simple as: this time, the weight of the metal added during the weld was unbalanced which now causes issues, when last time, it was better balanced. Or it could be the driveline shock of driving around with a welded differential causing damage to your drifeshaft or flex disc. There could be damage on the transmission end of the driveshaft, not just the flex disc at the differential end. How much driveshaft rotational play is there with the car in the air? That's probably where the vibration is.
It's probably as simple as: this time, the weight of the metal added during the weld was unbalanced which now causes issues, when last time, it was better balanced. Or it could be the driveline shock of driving around with a welded differential causing damage to your drifeshaft or flex disc. There could be damage on the transmission end of the driveshaft, not just the flex disc at the differential end. How much driveshaft rotational play is there with the car in the air? That's probably where the vibration is.
Racer
Joined: Mar 2018
Posts: 1,908
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From: Nevada
Thanks but - I mean - I'm an idiot. I don't know very much about welding differentials. I put my post together from just from 2 google searches I did along with my latent existing knowledge.
"welded differential deceleration vibration forum "
and
"LS400 welded differential forum "
This is where OP should be spending his time, not asking us here.
"welded differential deceleration vibration forum "
and
"LS400 welded differential forum "
This is where OP should be spending his time, not asking us here.
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 21
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From: Riverside
Thanks but - I mean - I'm an idiot. I don't know very much about welding differentials. I put my post together from just from 2 google searches I did along with my latent existing knowledge.
"welded differential deceleration vibration forum "
and
"LS400 welded differential forum "
This is where OP should be spending his time, not asking us here.
"welded differential deceleration vibration forum "
and
"LS400 welded differential forum "
This is where OP should be spending his time, not asking us here.
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 21
Likes: 0
From: Riverside
Either there is an issue with the installing of the differential, is it installed correctly and is it the right differential? Where did you get the replacement differential? If you didn't test the differential before the welding procedure you won't for sure if it was a good one or the right one. And who did the welding? It heats the heck out of it because of the heat from welding and that may or may cause a problem. You want to let them self cool after welding too. Sounds like the gears are binding, or some kind of an alignment issue. Just a matter of figuring out why, and what it is. It's already welded so now its just a process of elimination which might mean you will need to buy another differential that is not welded, install it, and see if the problem goes away.
this one came from my buddies same year Ls400 and he had no problems at all, just swapped it in for one that was already welded.
but when It came to welding this one i let my buddy give it a go and it looked much stronger and more stable / solid than the other one but he’s not a professional welder or anything so he could have done something wrong with that??
it’s just crazy to me how the issue started after putting the diff in but it was super super minor at first and got worse and worse on the drive home
also if it’s worth noting my driveshaft bolts on the diff end we’re loose when we were removing the original diff form my car
Thread Starter
Driver School Candidate
Joined: Dec 2022
Posts: 21
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From: Riverside
I hate to be that guy, but this is kind of what you get for welding the differential. It's a cascading waterfall of problems. Based on your other posts you're tracking the car so I get it, it's the cost of doing business. But I'm surprised traction is enough of a problem to have the solution be a welded differential. It's not like this car has 600 horsepower and it's struggling to put it's power down in third.
It's probably as simple as: this time, the weight of the metal added during the weld was unbalanced which now causes issues, when last time, it was better balanced. Or it could be the driveline shock of driving around with a welded differential causing damage to your drifeshaft or flex disc. There could be damage on the transmission end of the driveshaft, not just at the differential end. How much driveshaft rotational play is there with the car in the air? That's probably where the vibration is.
It's probably as simple as: this time, the weight of the metal added during the weld was unbalanced which now causes issues, when last time, it was better balanced. Or it could be the driveline shock of driving around with a welded differential causing damage to your drifeshaft or flex disc. There could be damage on the transmission end of the driveshaft, not just at the differential end. How much driveshaft rotational play is there with the car in the air? That's probably where the vibration is.
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From: CA
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From: CA
I just took a look at your profile, some of your modifications are; "welded diff, coils, cut/shortened front spindles, sway bar, FLCA, RCA, RLCA, engine/trans spacer"
So you have coils, and engine/transmission spacer, to name a couple of the modifications I can see there. I can say right off the top, once you alter the original geometry of the original drive shaft angles, and other angle of the driveline, you are asking for trouble. Any alterations of angles from Lexus spec angles with anything regarding your original seated positions, your lucky if it works without having problems. You can't put spacers in there and alter angles and expect nothing to go wrong, I understand why you did it but that's a no no unless you really know how to compensate for everything you through out of original spec. to make it right.
So you have coils, and engine/transmission spacer, to name a couple of the modifications I can see there. I can say right off the top, once you alter the original geometry of the original drive shaft angles, and other angle of the driveline, you are asking for trouble. Any alterations of angles from Lexus spec angles with anything regarding your original seated positions, your lucky if it works without having problems. You can't put spacers in there and alter angles and expect nothing to go wrong, I understand why you did it but that's a no no unless you really know how to compensate for everything you through out of original spec. to make it right.
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Posts: 506
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From: CA
You have way too much going on with modifications to even begin to understand where the problem is coming from in my view because the whole driveline isn't even correct in terms of factory spec. Companies that sell kits like to include things like spacers and other quick fixes that claim to make it right but I don't think so.