rear end adjustment and allignment???

[roadster408]

Hi,

I realized recently that my rear wheels are not properly aligned and that the right rear wheel seems to be further out on the rear and somewhat inward on the front. Needles to say, the alignment while driving is bad. THe right wheel is also too close to the body and the tire was lightly scraped when I had a passenger and went around some curves and/or bumps in the road. The left rear wheel appear straighter, and is further from the body on its outer edge.

I tried putting 2 big washers on the top of the rear leaf spring mount under the plate, and the bottom of the left mount in such a way that the right leaf was moved inwards. This corrected the problem somewhat and also improve the alignment.

I have diconnected and reconnected the rear end from the leafs and carefully reassemble several time but it keeps coming out the same.

According to my intepretation of the body specs from the manual the center of the differential case is less than 350 mm from the right leaf support, but I cant seem to move it to the left.

The center to center measurement between the front and rear wheels is slightly shorter on the right but is exact spec on the left.

I figure culprits can be:
THe brackets which one or more leaf mounts to:
One or more of the leafs
Bent rear-end/differential?
Bent frame (I have measured the distances between the front and rear leaf spring mounts and they are identical down to 1mm)

I have 2 more differentials so I can use one of these, but, I checked one of these and it seems like the distances mach the currently installed rear exactly.

Any suggestions?

[FergO2k]

<< I have diconnected and reconnected the rear end from the leafs and carefully reassemble several time but it keeps coming out the same. >>
Well, kudos to you, I doubt I would have been able to accomplish this feat!

Can't use the body, cause the body can be sitting non-square on the frame. Inbd/outbd between front and back is hard because unlike other cars, the track fwd/aft on a roadster is not the same. (as you well know)

But in other words, loosening and "knocking" the body about a bit can square up a close clearance, but truly before you start (a little too late) is have someone else drive your car and follow it in another, and try to figure out if it is going down the road "crab".
So then are the wheels crab or the body crab. If the wheels are crab then they will almost line up on one side,a nd be in line but offset on the other.
they should be offset on both sides. (yes, you will doa lot of swerving in the back vehicle, so pick an open road!)

This is the most telling way to find out. (next time you see a Ford F-100 truck from the 70's, and vans thru the 80's, nearly all are doing this! but nearly no VW's, hmmm.)
Have them drive really straight down the center of a non-crowned road, and try to tell if you are seeing more of one "side" of the car than another.

It may indicate that the rear end/leafs are fine, and you just need to "adjust" the body a bit to get rid of any scrape.

I doubt the rear end is bent, I'd be hard pressed to figure how you would do that, short of off-roading. You could move its position, but not the shape.

One way of looking at it is this:
Get rid of the fender scrapes first, then figure that 75% of the time the roadster is going around a corner anyway, so no one will notice.
So tune the suspension, drive fast and corner often, and don't sweat it.

[Nissanman]

My experience with aligning the body on to the chassis is this: the tolerance is ZIP!
Even though the captive nuts are on sliders and the holes are larger than the fasteners used, I could only get the bolts started when the body was in one position only.
Whereas the pickups mentioned have up to 40mm tolerance, the Roadster is 1mm at most.
I would do some tramming measurements, diff housing/rear axle to spring mounts etc and try to determine where there is a discrepancy.
Unless you know the complete history of the car, accident damage may be the culprit

[notoptoy]

My money is that the body is off kilter on the frame. However, body shops, and alignment places can do a 4-wheel alignment - though you may have to find one old-school that can handle a Roadster.
Nissanman, can you get all the bolts started, then coax the body afterwards? I am hoping so, as my front end is off to one side a bit and that was going to be my attempt to straighten it out.

[dbrick]

Best thing would be to get the car on a clean level floor, support it on the rear axle and take off the wheels. Get a plumb bob and drop marks on the floor from the front spindles, rear axle center at the drums, leaf spring mounts, anything you can think of to get a grid on the floor. You can snap chalk lines between points to get a representation of the axle centerline etc and see what is parallel to what. Then drop some marks from the body. this should give you an idea where everything sits.

[Nissanman]

notoptoy, not that I could achieve.
The four corners are non-adjustable fasteners and the sliders have to comply with them.
Believe me I tried, but there is very little adjustment if any!

[notoptoy]

Bummer, I need about a 1/4 to 1/2 inch!

[dbrick]

Can you enlarge the body holes and use BIG washers?

[redroadster]

The flange end of the rear end axle isn't bent is it ?

I had a number of later 311s and ,720's mostly that came in with a wheel bearing problem and found that the tube was bent also. most you couldn't even see the side gear splines ,but from the outside it looked straight

[roadster408]

Thanks for the suggestions.
I think I will do some body to frame measurement and see what that gives me.
I will report back.

Thanks again!

[Nissanman]

Can you enlarge the body holes and use BIG washers?

Well yes, you could, but that necessity points to another problem which may be a twisted frame or body, or both

[dbrick]

Can you enlarge the body holes and use BIG washers?

Well yes, you could, but that necessity points to another problem which may be a twisted frame or body, or both

Oh, defiantly agree with that, but if the frame isn't going to be straightened and it's just a bit off, might do it.

[RedSkull]

I do have a frame that is slightly offset in the front. I was hoping to get a slight adjustment in the rear to line the rear wheels with the front. But as this thread states, its not adjustable. I guess my tracking will just be a 1/2" off. I think I will just align the front as best I can.

[redroadster]

Does it dog track ? have a driver behind it to check , it's common to bend the diff housing ,back from hitting a pot hole but hard to see until you pull the Axle and look down the inside and can't see the end where the splines are