driveline movement
Cargo Master
Joined: Sep 2010
Posts: 3,427
Likes: 48
From: Hot AZ (Phoenix Valley)
I apologies if it sounded like I was saying that sway bars wouldn't help for this scenario, it will. And as stated above shocks are used to control body roll, but they control body roll by controlling the speed of spring (coil or leaf) motion. Sway bars controlling the left and right sides of the axles by a spring load under pressure from lateral force. Yes, changing springs can make a stiffer ride and probably will. Yes, we have been talking about a truck that aren't aerodynamic and with a high center of gravity, so prone to body roll. We must remember that not just one part of a suspension system is a stand-alone instant cure for all problems, not even a sway bar. Please correct me if I'm wrong!
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Senior User
Joined: Aug 2013
Posts: 355
Likes: 0
From: Peoria IL
Very good points.
I have a good list of things to improve.
I'll get to the springs & sway bar. But I need to fix the motion in the trans first.
All good advice tho. Keep the ideas coming.
I have a good list of things to improve.
I'll get to the springs & sway bar. But I need to fix the motion in the trans first.
All good advice tho. Keep the ideas coming.
Cargo Master
Joined: Sep 2010
Posts: 3,427
Likes: 48
From: Hot AZ (Phoenix Valley)
How about driveshaft length? Driveshaft balance? Check rear transmission bearing, movement of driveshaft at transmission? How much HP does the motor have? Are your mounts rubber or polyurethane mount?
Elder User
Joined: May 2012
Posts: 728
Likes: 2
From: North Idaho
Wow, Just spent some time going back and forth, reading and re-reading this thread,,,,and my head hurts.
Here are my feeling on the subject:
With an IRS, any IRS, the diff will not/can not, move unless their rubber isolators are shot, so there is no way the diff can Push the driveshaft forward, thus pushing the tranny/engine forward into the radiator. However, if the isolators on your Jag IRS are shot they could torque about 1/2 inch forward under heavy load but it sounds like you have a lot more movement than that.
If the tranny cross member is loose or the tranny mount is shot it would give you a side to side shudder, almost like wheel hop but not a forward movement of the entire drivetrain and surely not enough movement to drop the tranny into a lower gear during "pedal to floor" operations.
So, in my opinion you have bad engine mounts, either the mounts are bad, the hard-points to the frame are improperly gusseted, or maybe just loose mount bolts.
Take some time and look Very closely at your entire engine mount installation, the block mounts, the mounts themselves, and the frame mounts.
My guess is that if you motor is moving as much as you say, it's an engine mount problem.
Gary
Here are my feeling on the subject:
With an IRS, any IRS, the diff will not/can not, move unless their rubber isolators are shot, so there is no way the diff can Push the driveshaft forward, thus pushing the tranny/engine forward into the radiator. However, if the isolators on your Jag IRS are shot they could torque about 1/2 inch forward under heavy load but it sounds like you have a lot more movement than that.
If the tranny cross member is loose or the tranny mount is shot it would give you a side to side shudder, almost like wheel hop but not a forward movement of the entire drivetrain and surely not enough movement to drop the tranny into a lower gear during "pedal to floor" operations.
So, in my opinion you have bad engine mounts, either the mounts are bad, the hard-points to the frame are improperly gusseted, or maybe just loose mount bolts.
Take some time and look Very closely at your entire engine mount installation, the block mounts, the mounts themselves, and the frame mounts.
My guess is that if you motor is moving as much as you say, it's an engine mount problem.
Gary
Senior User
Joined: Nov 2009
Posts: 261
Likes: 0
From: Riverside, CA
Ok. If the engine isn't moving. I'll bet the body is shifting! That would explain the shifter moving and the radiator moving towards the water pump. This seemed obvious to me on page one. Engines don't move forward at launch, but the body will shift if it isn't secured correctly!
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Senior User
Joined: Aug 2013
Posts: 355
Likes: 0
From: Peoria IL
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Posting Guru
Joined: Apr 2005
Posts: 1,155
Likes: 7
From: Sweden (Fagersta)
Wow, Just spent some time going back and forth, reading and re-reading this thread,,,,and my head hurts.
Here are my feeling on the subject:
With an IRS, any IRS, the diff will not/can not, move unless their rubber isolators are shot, so there is no way the diff can Push the driveshaft forward, thus pushing the tranny/engine forward into the radiator. However, if the isolators on your Jag IRS are shot they could torque about 1/2 inch forward under heavy load but it sounds like you have a lot more movement than that.
If the tranny cross member is loose or the tranny mount is shot it would give you a side to side shudder, almost like wheel hop but not a forward movement of the entire drivetrain and surely not enough movement to drop the tranny into a lower gear during "pedal to floor" operations.
So, in my opinion you have bad engine mounts, either the mounts are bad, the hard-points to the frame are improperly gusseted, or maybe just loose mount bolts.
Take some time and look Very closely at your entire engine mount installation, the block mounts, the mounts themselves, and the frame mounts.
My guess is that if you motor is moving as much as you say, it's an engine mount problem.
Gary
Here are my feeling on the subject:
With an IRS, any IRS, the diff will not/can not, move unless their rubber isolators are shot, so there is no way the diff can Push the driveshaft forward, thus pushing the tranny/engine forward into the radiator. However, if the isolators on your Jag IRS are shot they could torque about 1/2 inch forward under heavy load but it sounds like you have a lot more movement than that.
If the tranny cross member is loose or the tranny mount is shot it would give you a side to side shudder, almost like wheel hop but not a forward movement of the entire drivetrain and surely not enough movement to drop the tranny into a lower gear during "pedal to floor" operations.
So, in my opinion you have bad engine mounts, either the mounts are bad, the hard-points to the frame are improperly gusseted, or maybe just loose mount bolts.
Take some time and look Very closely at your entire engine mount installation, the block mounts, the mounts themselves, and the frame mounts.
My guess is that if you motor is moving as much as you say, it's an engine mount problem.
Gary
Thread Starter
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Senior User
Joined: Aug 2013
Posts: 355
Likes: 0
From: Peoria IL
No rubber in the rear end mount. It's up there tight.
I jacked the truck up under the oil pan & the engine didn't move. The mounts look good.
I can't get anywhere near the tranny. The running boards are 6 inches off the floor so I can't tell if the X member is loose. The tranny is mounted tight to the X member though.
I jacked the truck up under the oil pan & the engine didn't move. The mounts look good.
I can't get anywhere near the tranny. The running boards are 6 inches off the floor so I can't tell if the X member is loose. The tranny is mounted tight to the X member though.
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Senior User
Joined: Aug 2013
Posts: 355
Likes: 0
From: Peoria IL
Ugh. I think I'd rather have movement problems.
The truck physically shifts the column shifter into 2nd gear & when I'm hard on it I can't shift back into dr. As soon as I let off the gas I can easily put it back in D
The truck physically shifts the column shifter into 2nd gear & when I'm hard on it I can't shift back into dr. As soon as I let off the gas I can easily put it back in D
Posting Guru
Joined: Jul 2012
Posts: 2,203
Likes: 4
From: Southern SC.
I had a bad gear (chipped tooth or teeth) in 4 speed that would shift from 1st to 2nd when I launch it -- didn't need the clutch at all it just did it at the right rev's. If I kept a little pressure on the shifter it would stay in 1st. This was in an Austin Healey with a built up FORD 289 and a 4 speed with the original AH rearend. I've never heard of this in an automatic but maybe it's a possibility.
Posting Guru
Joined: Sep 2012
Posts: 1,314
Likes: 1
Body shift was the first thing to cross my mind as well. Do you hear the mount areas rattle? Have a friend check the gap between the bed and cab if that's possible. See if it closes upon acceleration.
That could potentially be dangerous in a sudden stop or impact. You are in the cab.
Also, if I understand correctly, your vehicle has no shock mount (urethane or rubber flexible cushioning) at the differential or the transmission? That doesn't sound very well thought out by the folks who built (assembled?) it. I wonder if you'd be well-served by having a reputable builder go over it and make some suggestions.
I know this post looks harsh. I don't mean to be parental here! I simply care.
That could potentially be dangerous in a sudden stop or impact. You are in the cab.
Also, if I understand correctly, your vehicle has no shock mount (urethane or rubber flexible cushioning) at the differential or the transmission? That doesn't sound very well thought out by the folks who built (assembled?) it. I wonder if you'd be well-served by having a reputable builder go over it and make some suggestions.
I know this post looks harsh. I don't mean to be parental here! I simply care.