X7 cressida locked diff weird issues, serious help please!

[Barrington]

Hey guys, I have a stock x7 Cressida that I bought last week, I have a 1j ready to go in but no manual stuff yet so that's gonna wait til I have the funds. For now just so I have a weekend thrasher, I have cut the springs and welded the diff. I cut alot of the spring out so it is bloody low in the rear, but it caused no problems with the stock open diff. A few days later I welded the diff and took it for a test drive. Instantly the car violently pulled to the left, but not coz of the front end, you could feel the rear of the car forcing the car to pull to the left, it was as though there were issues with the drivers rear side. It drove as though the rear wheels were not inline with the car, but when I'd apply the breaks normally, the car would instantly straighten up like normal until I got off the breaks. After about 10 ks of driving, smoke was coming out from the drivers rear wheel, burning oil. Then after 20 ks the drivers cv joint blew, the joint closest to the diff. and there was oil or lube from the cv everywhere. So me and the other guys helping me build the car were mind boggled, as the car drove totally fine before the diff was welded. Last night I took the cv shafts out, and put in another set, drove about the same distance, the car still pulled to the left, there were no differences, the cv joint on the drivers side didn't blow but the boot split and the cv shaft was bloody hot. The car is fairly mint so I don't reckon the chassis is bent, and sure the car is low but it's got fine angle on the cv's, like opposite angle to stock if that makes sense. Can anyone help me with why the car does not drive straight and why the cv's are copping a beating?

[madmont]

[QUOTE=Barrington;136 Can anyone help me with why the car does not drive straight and why the cv's are copping a beating?[/QUOTE]

someone welded up the diff

[crownv8]

^^^^^^^^^^^^^^^

Cars have differentials for a reason. Locking it for the road makes no sense. Especially for a relatively heavy under powered car.

Are both your rear tyres exactly the same size? If not that will make it pull and put lots of strain on the cv shafts.

Have you had a wheel alignment after lowering it four inches? Are the rear bushes in good condition?

Have you got another diff to put in???

[Barrington]

I've never had any problems with welding diffs before, a mate is driving an mx83 with a welded diff and it's seriously low aswell, and that's his daily.

This car is being set up for the track, but it is registered. Tyres are the same but I should double check the pressure.

When I force the car to drive in a straight line, the drivers rear wheel skips as though i am turning in a carpark at full lock. It's as though the drivers rear wheel is either spinning slower or faster than the other rear wheel, but I checked the diff last night and it's definately working normally. It's bloody weird.
Subframe bushes are average, but not horrible, and I do have a spare diff, I have a whole spare car.
I'm just gonna put it back to stock height and put stock wheels on it and see what it does with the locker.

[Silly Rabbit]

LOL....just wait until it rains....then post pics of where the car ends up

[crownv8]

Did you weld all the gears up or just weld one gear to the housing???? Just doesn't sound right, even for a locked diff. Somehow you have it trying to spin on wheel faster than the other. You might have just stumbled onto a revolutionary idea for NASCAR. I'd rush out and patent it.

I still don't think locked diff are a good idea. Also, the mx83 rear suspension is vastly different to the mx73.

[SilverRA23]

It very much sounds like you have welded it incorrectly.. something is still turning faster one side than the other... that will be whats giving you the awesome turn in one way vs the other... and why your cv is turning into a smoking pile of sh*t as its trying desperately to keep up with the other side.

But as most of the sane people here are saying.. the welded diff is a shit house idea for the road.

[Barrington]

It very much sounds like you have welded it incorrectly.. something is still turning faster one side than the other... that will be whats giving you the awesome turn in one way vs the other... and why your cv is turning into a smoking pile of sh*t as its trying desperately to keep up with the other side.

well thats what i thought, so i pulled the diff out thinking that it was welded incorrectly, and while it was out i checked to see if each axle was still spinning the same, and everything matched up no matter how much i turned it. But i dont even get how its possible for a welded diff to beable to spin more on one side than the other, its welded together, but I have heard of it happening before.
All gears are welded together.

I dont get why everyone is against a locker for the drift. I would never rep one in a car that I drove normally on the road, but this car is gonna be on the track mostly. Even the serialnine brown x7 cressida has a locker

[CELICASUPRA7M]

got any pics of welded center? you shouldnt be having any issues with this set up, MANY F series LOW irs cars have been done the same way with no issue.

[andrew_mx83]

are you SURE the tyres are the same?

just let some air out of the right one and you'll be fully track-ready.

[Suavemechanic]

just for me....... grab a bit of string and check centre to centre distance of the wheels down each side , then check the toe in on the rears
the " goes ok when i hit the brakes" part might be a clue. any thing loose like an isolating bush ? trailing arm mount ? ( not familiar with the set up , but some thing is' floating ' )
next are the brakes working nice ? as in jack up and test each wheel for dragging and sticking ,and working when your assistant applies the brakes (and loose the line locker err ....vice grips on the soft hose)look forward to hearing when you find it

ps i have no opinion on welded diffs other than they are a bugger to push in the workshop !

[Barrington]

so turns out it was all because of the wheels. Either one of the rear wheels was slightly buckled or there was seriously uneven wear. The pressures were close enough. I borrowed a set of meshys off a mate, and we kinda forgot about how he had an acco with these wheels on his car.

How we found this was, we put stock wheels on the rear and stock uncut springs in the rear, so it was back to stock in the rear but with a locker. All problems had gone and it seemed to drive fine. Then we put the meshys back on the rear with the stock uncut springs still in, that way we could rule out either the wheels or the cut springs and the cars lowness. It pulled to the left again like before, then I swapped the rear wheels around with eachother and it pulled to the right real bad. So I put the stock wheels back on and chucked the choppies back in and the car drives fine now. Its been a few days and shes still goin strong with no strange noises or anything. Thanks heaps for everyones inputs, really appreciate it. I just cant beleive it was all because of the wheels.

[Suavemechanic]

i will have a dollar on the offsets being different....