Front end tramps when turning right

[Slick7g]

 

[87VLCALAIS]

Never heard of it before. Just had a look at the programme and some video from other years. Looks like a great weekend. We're away elsewhere that weekend and in Taupo the following week otherwise I'd be keen on having a look.

 

[87VLCALAIS]

We're getting right off topic now. Very cool car. I guess you don't drive on the road very often.

 

[Slick7g]

We're getting right off topic now. Very cool car. I guess you don't drive on the road very often.

Haha yea a little of topic. I do actually drive it a fair bit. Done 9000kms in 3 years. And I don't baby it either lol

 

[87VLCALAIS]

Back on topic. Let us know what you find out with the front end issues. What was it like before you fitted the aftermarket springs and the 20"rims? The fact that replacing the after market springs with the OEM ones improved things is a step in the right direction to solving the problem. I wonder what it would be like with the original 18" wheels?

It must be possible to successfully fit the bigger rims to the ZB.

I know the guys in the US have successfully changed rims and springs on their Buicks which are basically the same car. Perhaps sign up to the Buick Owners forum and go to the 2018+ Buick Regal Sportback and Tour X Forum and ask some questions on there. https://buickforums.com/forums/forums/2018-buick-regal-sportback-and-tourx-forum.135/

 

[Slick7g]

Back on topic. Let us know what you find out with the front end issues. What was it like before you fitted the aftermarket springs and the 20"rims? The fact that replacing the after market springs with the OEM ones improved things is a step in the right direction to solving the problem. I wonder what it would be like with the original 18" wheels?

It must be possible to successfully fit the bigger rims to the ZB.

I know the guys in the US have successfully changed rims and springs on their Buicks which are basically the same car. Perhaps sign up to the Buick Owners forum and go to the 2018+ Buick Regal Sportback and Tour X Forum and ask some questions on there. https://buickforums.com/forums/forums/2018-buick-regal-sportback-and-tourx-forum.135/

It drove good with the factory 18s, but was terrible in the wet and the rear end would let go when on open road in corners. So decided to fit the king springs and wheels at the same time. It fixed the rear, but screwed the front.
Have a look at the pic. The springs didn't really drop it much at all

 

[87VLCALAIS]

Here's link to a thread on the Buick site about rim sizes. https://buickforums.com/forums/threads/has-anyone-replace-their-tourx-wheels.50325/

This is an article linked from that thread. An interesting read. https://web.archive.org/web/2011112...es/effects-of-upsized-wheels-and-tires-tested Perhaps your improved grip was due to a different tyre/tread pattern rather than the rim size?

 

[Not_An_Abba_Fan]

It's not the rolling diameter, it's the rim diameter vs the factory spec. Different rim diameters and offsets change the way the machine reads, so a 2mm toe in on factory rims will be more like 3 or 4mm on a rim with a more negative offset as the outside of the wheel will travel through a wider arc. The settings have to be compensated for when fitting different diameter and offset wheels.

Some machines have an input for offset so it compensates automatically, but some don't.

 

[Skylarking]

@Slick7g, I’ve found older mechanical AWD‘s can be rather sensitive to tyre compound changes, that is same size but different rubber can upset the vehicles balance.

But you have a modern AWD system that use electronics and multi plate clutches to handle power distribution. As such they system needs to know what is what and as such the engine, gearbox and ESC/ABS calibrations may be specific to the factory fitted wheels and rubber for your model variant. This means that if you throw on a different set of wheels that have different widths and offsets and use different rubber compound, the vehicle dynamics may change for the better or for the worse, it may become skittish.

Lowering the car can also have a negative side effects as well. Lowering and changing wheels at the same time may make sorting out what is causeing poor dynamics more complex.

So, if you still have the original 18” wheels I’d reinstall them to the vehicle and see how it drives. That way you’ll be able to discount issues with the vehicle being lowered a little. If the vehicle still tramps at the front and slides at the rear with the original wheels, as it did before, you know the slight lowering didn't cause any negative issue. At this point i'd go to a good wheel alignment place as they should be able to determine if anything is bent as you suspect. But they need to know their craft...

I suspect installing wong wheel offsets and widths will impact scrub radium and still cause vehicle balance issues even with hyperstrut (which is supposed to decoule drive and steering issues, not be a panacea for ill fitted wheels).

Some machines have an input for offset so it compensates automatically, but some don't.

And unfortunately many wheel alignment places don’t really have knowledgable people operating the equipment. Results can be less that great.

One really needs to find a specialist that understands wheel alignment principles, suspension and steering mechanics as well as the capabilities and limitations of the machines they use. They in particular need to understand hyperstrut suspension as diagnosing failing bushes and/or bent struts may be more difficult with these designs.

 

[87VLCALAIS]

This car is not AWD nor does it have hiper struts fitted. It is an RS FWD 2.0L turbo.

However your comments about rim size, offset and tyre width are no doubt relevant.