16 replies to this topic

[YankWithAMini]

I recently finished a lot of work, and the car now sits 3cm lower on the right side (at both the front and rear wheels). I took some measurements, mostly at the rear as it is easiest to access. Suspension setup is stock (no Hi-Lo), with the exception of adjustable lower arms in front.

 

1. Front left upper arm is on the bump stop, the front right arm has space between the bump stop and the arm.
2. On the left side, the bottom of the damper is flush with the bottom lip of the frame, while the bottom of the damper on the right side is 3.5 cm above the lip of the frame (frame sits lower).
3. From the rear lip of the trumpet to the metal band on the cones is very similar, with the right cone 3mm shorter. This is with full car weight on the wheels.
4. All cones appear to be seated correctly.
5. The right rear tire has large positive camber. Maybe related, maybe not?
6. The plastic cups for both rear knuckles have a few mm from the radius arm to the lip of the cup, but it is the same on both sides. Not sure if both aren’t seated fully or both cups are just too deep. I would have thought the weight of the car would seat them.

 

Here is what was done to the car before the issue developed:

1. 4 new suspension cones
2. Rebuilt all suspension arms, front and rear. Rears were done by a Mini specialist.
3. All new knuckles and cups
4. Rear subframe refresh (all new bolts, bushings, etc).
5. Alignment by a shop. Front for sure, can’t remember if rear was checked.

 

I had the Mini specialist look at it while in for something else, and the consensus was that it just needed to settle. This work was all done over 4 months ago, and the car has maybe 100 driving miles since then (yeah, need to drive more, but we were in the process of moving). The car was trailered over 1000 miles though, which I would think exercises the cones at least some.

 

I’m not sure what to do next. It seems that the rear cones have close enough to the same compressed height to call it good (?). Knuckles seem the same. I’m not sure what else to measure to help figure it out. The fact that the front and rear both have the same amount of unevenness seems like too big of a coincidence.

 

This post discussed worn arm cups. I did reuse my arms, but since my issue is on front and back I’m not sure if this would apply.

https://www.theminif...+uneven +height

 

Any ideas what to check next?! I hate to just start taking it apart to check it over with no idea what to look for.

 

 

 

[Designer]

Hi,

 

You have kept the trumpets all round and replaced the knuckles. Could it be that the original set up had the extra spacers between the trumpet and knuckle. With pure coincidence have the spacers (part no at Minispares21A1845) on one side stayed stuck to the bottom of the trumpets and those on the other side stayed stuck to the knuckle and therefore been discarded.

Just a thought as the spacer is about 3mm thick.

 

Paddy

[Spider]

The 3 mm spacer that Paddy mentioned will give a 15 mm rise in rise height.

It may also be that the trumpet(s) may have been shortened, however, I would suggest replacing the cups for the knuckle joints first and while it's all apart, check the trumpet lengths and also the sockets in the arms haven't been worn in to from failed cups.

I'd say the issue you are seeing is likely on the front suspension. As the front is much heavier than the rear, the rear tends to follow the front.

Ideally, you'd want to be checking corner weights, but that's easier said than done.

 

What I have done, with a high degree of accuracy is to slip a length of angle iron over the rear rail of the rear subframe and clamp that in place then accurately mark the centre of the rear subframe on to that (measure from the mounts) then strap up a steel bar under the gearbox and make a centre line mark on that (measure off the front mounts).

Then making sure the car is settled on the suspension and it's on a flat level floor. Use a jack under the back end first, place a stud or bolt longitudinally under that mark on the angle iron and raise the back end just until the rear wheels are airborne, then measure the font body heights on each side, write them down. Do the same for measuring the rear height, but be sure to bounce and rock it around to settle it before jacking the front end up.

This process will show you where the ride height errors are and by how much.

You can then trim the height using the factory method of the spacer washers that Paddy suggested, or just cut out the middle man and fit hilos. If fitting washers, you are limited to a maximum of 0.200" or 5 mm. It's dangerous to fit anymore.

[nicklouse]

Un even ride height is main an issue at the front. 
check the high side first for correctly seated rubbers.

pictures would be good as they can be much clearer than words. 

[DeadSquare]

Perhaps, unintentionally, you have set the car up so that it will be level when you sit in it.

[YankWithAMini]

Awesome, everybody! Thanks for the suggestions. I was given a list of "honey-do" items, so it might be a bit before I can get back to the car. I had taken pictures, but they weren't great, so I will try again.

[YankWithAMini]

Finally had some time. I took some pics, but mostly am posting pics of the front parts for now for this reason: I jacked the car up one end at a time, and when I did that, the rear ride height had a 0.5cm difference, but the front had a 2.8 cm difference. That seems to tell me the issue is in the front. I did post the pics of the rear dampers to show the difference. I can't tell much from just looking at things where the issue is. Nothing jumped out at me that seemed off. I guess I will just take it apart and put it back together to make sure.

 

I think I mentioned previously that I don't remember any spacers being on the trumpets when I took it all apart. Is the size of the discrepancy such that spacers would be a valid way to fix it, or is it a sign of a more serious problem?

 

One interesting note: all of the lower arm bushings were torn. The flange, or lip, was almost totally torn off and there was metal to metal contact, for example, between the lower arm pin and the lower arm. These bushings were all replaced 4 months and <200 miles ago. I can't remember the part number I used. I see MiniSpares has an uprated set for cars with adjustable suspension (C-STR632), and I do have the adjustable lower arms and tie rods (not to make it sportier, just to better dial it into stock settings). Maybe I should try those?

 

If you see something that jumps out, let me know, or if you have any other suggestions.

 

 

Attached Files

•  dampers.jpg   31.3K   8 downloads
•  Front arm stops.jpg   37.26K   8 downloads
•  front cones.jpg   37.09K   10 downloads
•  front knuckles.jpg   36.25K   7 downloads

[Spider]

It's a little hard to make out with certainty from your photos however it looks like the Front Right knuckle joint is seated lower than that of the left side.

 

This could be from a worn knuckle joint cup or if the cup has worn through at some time, the arm itself might have a worn socket.

[Designer]

Hi

 

Looking at the second pair of pictures there seems to be a gap between the right upper arm and the bump stop and no gap on the left side.

If I am not mistaken this would confirm what Spider sees as the weight of the car would push the upper arm higher if the knuckle is allowed to move further into it's socket in the upper arm.

 

Paddy

[sonscar]

Worth checking the front right cone as it may not be correctly seated in the subframe.Steve..

[YankWithAMini]

Front suspension is apart. Findings:

 

1) Trumpets are the same length.

 

2) The right cone is about 1 mm shorter than the left (after allowing to sit for several hours). Probably not enough to create such a big drop on the right side, I would think. Both cones are the same PN.

 

3) The knuckle cups looked OK. I used the link I referenced in my first post, and both cups looked like they were conical. Maybe a slight bit of rounding on the left, but very very slight, probably nothing of significance. The left cup did seem to fit slightly more down into the arm (picture attached), but if that was an issue it would result in the left side being too low, and my right side is too low.

 

4) Subframe mounts looked OK. Didn't notice any cracks in the frame or tower area. Both of the rubber tower pads were in place.

 

5) When I got the car up on jack stands (so the front is now very close to level left to right), the rear dampers still exhibit a difference in height, in that the lower damper bolt is farther above the frame level on the right side, indicating the right is sitting lower. I would have thought having the front level on stands would have fixed this if the problem was the front suspension. Faulty logic, or is it telling me something?

 

 

My plan is to put it all back together, but switch the right cone to the left side to see if the issue follows.

Attached Files

•  20240923_160340.jpg   35.52K   1 downloads
•  20240923_160121.jpg   48.89K   2 downloads

Edited by YankWithAMini, 23 September 2024 - 10:47 PM.

[Lplus]

Firstly it doesn't matter how far down the top of the plastic cup is, the important dimension is the distance from the bottom of the cup (fully pressed in) in relation to the line between inner pivot and the outer end of the arm - assuming the taper holes are the same width and thus the hubs sit at the same distance below the arm.

 

Secondly, are those refurbished replacement arms or are they the originals from the car?

 

Thirdly, if the car is supported in the centre at the front and the rear is still down on one side, then the rear also has a problem.

[Designer]

Hi,

 

Looking at the photo of the arms to me it looks as if the overall size of the left one is bigger than the right.

Measuring on the screen the distance from the lip of the recess for the knuckle cup to the back of the left arm measures approx  53mm, the same  measurement on the right arm is approx 48mm.

It could just be the angle and position of the camera.

[YankWithAMini]

I will see if I can check the measurements of the cups when I push them in.

 

I assume the arms are original. There is ~46k miles on the odometer, and I haven't replace the arms. I refurbished them a few months ago (bearings, seals, paint, etc).

 

The arms are the same size, they just looked weird due to the photo angle.

[YankWithAMini]

Progress, finally.

 

Everything is back together. New knuckle cups and new lower arm bushings (more on that in a bit). The only thing that looked not "by the book" was that I hadn't cleared the small holes in the bottom of the suspension arm socket where the knuckle cup fits. Now, the distance from the lower bump stop (rebound buffer) screw hole to the bottom of the lower arm is identical on both sides. The height difference of the body is better, but not perfect. It is now 1.5 cm higher on the left when it used to be 3 cm higher on the left. The lower mounting bolt for the left rear shock now sits about 1 cm closer to the lower subframe lip compared to the right side (both sit above the lip). Guess I will need to take the rear apart to make sure it is all seated correctly too. Sigh....

 

I attached a pic of the lower arm bushings. They were only a few months and under 200 miles old and are totally destroyed. I wondered about over tightening, but I always use a torque wrench and check the book values. I replaced them with the "upgraded black poly type", but I am fairly certain that is what was in there before. Wondering if the last alignment shop set it up in a way that stressed the bushes too much? I had requested a stock setup, nothing sportier.

 

Right rear tire has 2 degrees positive camber, left rear is 0.2 negative. Won't worry about that until the height thing is fixed in case it is related. Although, if I'm taking the rear apart anyway, a set of adjustable brackets might not be a bad idea!

Attached Files

•  20241009_181040.jpg   64.36K   5 downloads