[TJ] Vibration through accelerator pedal under load, at speed

[ammerty]

Hi guys,

My TJ has developed an annoying issue in the last few weeks where it will transmit a a harsh vibration through the accelerator pedal and floor at highway speeds (80kph+) under load. The vibration will persist and worsen depending on how long you keep it under load but disappear upon taking your foot off the accelerator, even at speed. The vibration doesn't occur at lower speeds, and it doesn't sound like a misfire.
I had originally thought that it could be a wheel alignment/balance issue, but after having it done it was clear that the vibration wasn't through the steering wheel, but rather through the engine bay or front floor area.

The Magna has done 258,000km, parts of relevance that have been replaced include:

• Lead set in April 2012 at 186k
• RH Upper Mount when the timing belt was done in May 2012 at 189k
• All 6 Spark Plugs, replaced with platinum types, in February last year at 216k

Could it be possible that the engine mount has failed again after 70,000km? Could CVs possibly be the issue (despite not feeling the vibration through the wheel, and there are no signs of other issues such as clocking at low speed turns, etc)?

I'd appreciate some constructive insight, thanks in advance!

Dann

[DeanoTS]

Hi guys,

My TJ has developed an annoying issue in the last few weeks where it will transmit a a harsh vibration through the accelerator pedal and floor at highway speeds (80kph+) under load. The vibration will persist and worsen depending on how long you keep it under load but disappear upon taking your foot off the accelerator, even at speed. The vibration doesn't occur at lower speeds, and it doesn't sound like a misfire.
I had originally thought that it could be a wheel alignment/balance issue, but after having it done it was clear that the vibration wasn't through the steering wheel, but rather through the engine bay or front floor area.

The Magna has done 258,000km, parts of relevance that have been replaced include:

• Lead set in April 2012 at 186k
• RH Upper Mount when the timing belt was done in May 2012 at 189k
• All 6 Spark Plugs, replaced with platinum types, in February last year at 216k

Could it be possible that the engine mount has failed again after 70,000km? Could CVs possibly be the issue (despite not feeling the vibration through the wheel, and there are no signs of other issues such as clocking at low speed turns, etc)?

I'd appreciate some constructive insight, thanks in advance!

Dann

My old KR Verada had a very similar problem, it was the drive shaft, not the CV end but the other end the tripod joint end of the drive shaft was badly worn so it would spin out of balance but only would do this underload on the highway like accelerating up hills on the freeway.

[MadMax]

TS at 220,000 did this, 80 KPH vibration through the floor. Turned out to be front ball joints.

I knew the drive shafts were good because I had just rebuilt them - start there, if they are old. A tight spot in one of them will cause vibration.

To check the driveshafts for tightness, they need to be removed from the car, to check ball joints, these need to be disconnected and checked for turning torque.

[TW2005]

My old KR Verada had a very similar problem, it was the drive shaft, not the CV end but the other end the tripod joint end of the drive shaft was badly worn so it would spin out of balance but only would do this underload on the highway like accelerating up hills on the freeway.

+1 For checking this. V6 Galant 1994, 280 000 + Ks, inner CV joint, worn out and housing had a fracture. Symptoms were, 80+kph, whole front shook but not felt through steering, worse under load and acceleration especially up hills. Would balance out just over 100kph, got really bad on very long highway runs up hills.

https://performanceforums.com/forums/...1&d=1353844179

https://performanceforums.com/forums/...2&d=1353844191

https://performanceforums.com/forums/...3&d=1353844202

[Madmagna]

Sounds more like the torque converter clutches from what you describe, get a tube of shudder stop from somewhere like repco and pop that in first.

Make sure you get the right one, is a little red tube

[ammerty]

Thanks for the pointers guys, I really appreciate it. I'll try and get a hold of some shudder stop and see how I go with that over the weekend.
I have it booked it for Tuesday to have the problem looked at, so hopefully we'll also have some answers then.

[Andrei1984]

i have had vibrations come and go in my TJ all due to the following different issues, all happened at different ks on the odometer

under acceleration at high speeds - CV joints
vibration at high speed regardless acc or not - control arm bushes
slight vibration at high speeds - engine mount
and obviously the most common one wheel balance

torque converter, you can test out by dropping it in 2nd, as you can do highway speed in 2nd for short time, if it still vibrates the same even in 2nd gear its probably not the cause.

[alchemysa]

i have had vibrations come and go in my TJ all due to the following different issues, all happened at different ks on the odometer

1. under acceleration at high speeds - CV joints
2. vibration at high speed regardless acc or not - control arm bushes
3. slight vibration at high speeds - engine mount
4. and obviously the most common one wheel balance

torque converter, you can test out by dropping it in 2nd, as you can do highway speed in 2nd for short time, if it still vibrates the same even in 2nd gear its probably not the cause.

An excellent answer Andrei. Number 1 was problem I had.

[ammerty]

Thanks guys, I'm hoping its just CVs/Shafts, but anticipating worse.

[ammerty]

Following-up on this problem, the vibration was diagnosed as worn CVs by my mechanic.
Had both sides' joints and shafts replaced and it now drives a treat. Drove from Brisbane to Bundaberg tonight with no sign of the vibration returning.
At a guess, I'd say they were the original items, so at 260,000km, I think I got good mileage out of them.

Thanks to everyone who replied with their ideas on the issue, much appreciated