Axle Tramp???

bartsau · 22-01-2010, 03:36 AM

Hi guys, not too sure what it is. Just have had my car (AU wagon) converted to manual. When i take of a fair bit quicker than normal it feels like the rear of the car is bouncing up and down and there is a bit of a thumping noise.

Is this axle tramp??
If so does anyone else get it in their wagons or utes?? And how can it be fixed. I will be fitting rear leaaf springs with and extra leaf and lowered more so in the next few weeks. Other than that everything should be in good nick.

Thanks, Rhys

The Monty · 22-01-2010, 06:35 AM

Pretty sure axle tramp is when you launch hard with IRS, and the wheels bounce at odd times (syncopated) with each other, happens with a bit of wheelspin, thus creating the rabbit feel in the back of the car.

What your talking about, and I assume you mean at a decent speed (near the limiter) would probably be the tailshaft about to snap and embed itself to the undercarriage of your wagon.

Mine does it around 160 (at the drags), get a violent shake in the rear end, this would be around 210km/h if I was using 3.08 diff gears.

Mr Hardware · 22-01-2010, 10:13 AM

You don't need IRS for axle tramp, believe you me. I tell ya, you'll friggin bloody well know when you have axle tramp, and it ain't much fun. It mainly happens with leaf springs, and it'll mainly happen only in first gear, and it'll mainly happen when you're trying to drop a nice smooth burnout and all you get is this blasted hopping from the rear wheels jumping and the bloody springs not being able to keep the tyres to the road, it's really, really annoying. However it is not limited to leaf springs as I have seen an LS1 VX commodore do it.

Now axle tramp can be fixed. There are a number of different ways to go about it, and i most certainly don't know them all. The AU's leaf pack is not terribly strong, and can be replaced with a stronger unit. This is probably what will help the most. You can also get/make anti-tramp bars that limit the flex of the leaf, apparently that's the way to go. Other than that you can look at different tyres (traction) or different wheels (unsprung weight). Now i don't really know the maths on it all but if it is axle tramp, you've got a bloody annoying problem that I wouldn't wish upon anyone.

/edit: sorry about getting a bit worked up, once you've had a car with seemingly incurable axle tramp, you kinda have a big hatred for it.

The Monty · 22-01-2010, 04:31 PM

And as the OP said, it happens when he is going fast, not taking off, so its NOT axle tramp. And thanks for correcting me, I assumed it would be the same for leaf springs, seeing as they are completely independent from the other side, hence having the same problem. You wont get this with a live rear.

SLO AU XR8 · 22-01-2010, 05:42 PM

Quote:

Originally Posted by The Monty

And as the OP said, it happens when he is going fast, not taking off, so its NOT axle tramp. And thanks for correcting me, I assumed it would be the same for leaf springs, seeing as they are completely independent from the other side, hence having the same problem. You wont get this with a live rear.

you can, and do get it with some live rear cars

The Monty · 22-01-2010, 05:51 PM

How do you get it with live rear? Just wanting to learn is all?

**Mont5.0** · 22-01-2010, 05:56 PM

the OP says he gets it when taking off quickly. and Yes Leaf sprung vehicles are more prone to it.

FTE72 · 22-01-2010, 06:06 PM

Axle tramp is definately a problem in live axle cars as much as it is in IRS cars. As Monty has said, it is caused by the tyre slipping and then gripping under hard acceleration which causes the diff to effectively"bounce" up and down as the suspension tries to overcome the loss of traction and the engine power tries to overcome the grip. It is all related to excess movement between components.
Most of the time, the tramp problem can be relieved by replacing all rear suspension bushes with new rubbber, or preferably nolathane and new shocks. In higher powered/modified cars with bigger, stickier tyres, bushes and shocks alone may not cure the tramp and will require tramp rods to stop the wind up of the spring pack.
This is the problem as I understand it and have overcome it.
I think you should post this in the Fulcrum Suspension or Pedders area for an expert explanation.

T3man · 22-01-2010, 06:36 PM

The simplest fix is a decent set of shocks. If your car has only started doing it since you changed to manual it indicates the tramp isn't bad (or it would have been present before). Shocks should fix it.

Driving style also has a lot to do with it - dropping the clutch will exacerbate the problem and may even be the sole cause of it. Get some good preferably adjustable shocks (Konis) and practice a more gentle clutch release. Even worn tyres can be another cause. And, depending on power even new tyres aren't in themselves going to stop it.

If the problem persists fitting an LSD will help (if the car doesn't have one already).

PS Fitting stiffer springs will worsen the problem. If your shocks aren't controlling spring rebound/windup now, then they certainly won't handle stiffer springs.

The Monty · 22-01-2010, 07:01 PM

Quote:

Originally Posted by Mont5.0

the OP says he gets it when taking off quickly. and Yes Leaf sprung vehicles are more prone to it.

Well, that was another epic fail by me by not reading the opening post properly, thanks for setting me straight.... (slinks off to cook tea)...

bartsau · 22-01-2010, 11:36 PM

Ok guys i think it is fair to say it is axle tramp. I will be fitting in the next couple of weeks a different set of springs (standard + 1 extra leaf) Along with this i already have nolathane bushes to replace everything except the eyes at the front of the spring (front mount point).

Quote:

If the problem persists fitting an LSD will help (if the car doesn't have one already).

Also, i will be putting in my lsd (stock rebuilt about 5000k's ago).

Quote:

Driving style also has a lot to do with it - dropping the clutch will exacerbate the problem and may even be the sole cause of it. Get some good preferably adjustable shocks (Konis) and practice a more gentle clutch release. Even worn tyres can be another cause. And, depending on power even new tyres aren't in themselves going to stop it.

I have 18x8's all around and the tyres are only about 3000k old (Tons of tread left). It has pedders sports shocks in it and they are about 50,000km old i think. As for driving style i have only had the manual fitted for a couple of days and i was just seeing how it would help me get off the line. (Just having a bit of a play)

I think i am due for a trip to my local pedders to see what the bloke there has to say. And thanks for the info everyone.

blownv8au · 23-01-2010, 12:17 AM

yeah its axle tramp i get plenty in my ute(manual). i still get it after doing pedders lowest leaves, nolathane eye bushes, munroe gt sport shocks and sway bar kit and it and thats with a 215 -60 tyre and also with 285-35. so my next step is cal tracs or true tracs but they're not cheap around $700 so if your keeping your wagon and or uping the power i would go for a set they should knock it on the head pretty quick.

T3man · 23-01-2010, 12:55 AM

Pedders shocks (mostly) are garbage - sorry but it's true - get some decent shocks and you'll notice the difference straight up.

Stattic · 23-01-2010, 02:08 AM

Quote:

Originally Posted by The Monty

What your talking about, and I assume you mean at a decent speed (near the limiter) would probably be the tailshaft about to snap and embed itself to the undercarriage of your wagon.

Mine does it around 160 (at the drags), get a violent shake in the rear end, this would be around 210km/h if I was using 3.08 diff gears.

wow that sounds dangerous
i suppose my car with 3.9s would do the same? should i look out for this?

The Monty · 23-01-2010, 07:03 AM

Keep an eye on it. AU's are limited as the tail shaft is ultra long and around the 180km/h mark, can get vibrating and break (and yes, it does happen). When we put the 3.9's on this brings down that speed to around 136-140.

**ebxr8240** · 23-01-2010, 07:19 AM

Check drive shaft ballance ?? It MAY have been put back on off centre ??
If it's an alloy shaft ?? Check for dents, any weights that may have come off...
Oh any shaft for dents for that matter..
Check uni joints also??

The Monty · 23-01-2010, 08:01 AM

I deffinately need to get mine balanced. Anyone know of anywhere in Brisbane?

Beer Baron · 23-01-2010, 12:14 PM

Brisbane drive line services, 56 Colebard St East, Archerfield.

They did my custom tailshaft for my corona a few years ago. I didn't have any problems at all with vibrations. They made the shaft up from measurements i gave them and it was a perfect fit.

ronwest · 23-01-2010, 01:43 PM

Quote:

Originally Posted by The Monty

I deffinately need to get mine balanced. Anyone know of anywhere in Brisbane?

My bro-in-law had his done at Brisbane Driveshaft Balancing at Brendale.

He was happy with the results.

Actually, I might get mine balanced before our Cairns trip in April. I've got a bit of a vibe through the seat so it won't hurt to rule out the tailshaft.

ebxr82nv · 23-01-2010, 02:17 PM

off topic post kinda but of the 3 cars I've had that have had alloy tailshafts AU2 XR8 ute, EB2 XR8 sedan and AU1 XR6 sedan not one of them has suffered from the tailshaft looping people talk about. All three cars saw 200kph plus on numerous occasions.

bartsau · 23-01-2010, 10:01 PM

Quote:

Check drive shaft ballance ?? It MAY have been put back on off centre ??
If it's an alloy shaft ?? Check for dents, any weights that may have come off...
Oh any shaft for dents for that matter..
Check uni joints also??

I had to have a custom made steel driveshaft as the auto one was too long and being alloy no one wanted to shorten it. However, i don't think that it is all that well balanced.

Rhys