Some advice on a Chevy Suspension Upgrade

[Deano]

Originally Posted by cruising7388

When you changed over to your current tires and rims, did you experience any difference in ride quality and handling on the road?

Yes, most notably, bump steer was eliminated and lane wander was diminished. I attribute this to the tie rods now being parallel to the road, instead of at an angle they were with the zero offset Prime wheels.

Also, I went with Michelin LTX MS2 tires, they have a reputation of a better ride than the Bridgestone OE tires. I was running 65 PSI front and 80 rear.

I just returned from a trip to Yellowstone. All of the roads in Yellowstone and those on US 89 down to Brigham UT are up and down with sharp curves. Except for the need of new/better shocks, I was very surprised and pleased with the handling with a stock suspension. (Especially after reading of some of the handling problems others have experienced on this forum) Unless you consider 1/2" wider wheels and one size larger tires modified.

[cruising7388]

Originally Posted by Deano

Yes, most notably, bump steer was eliminated and lane wander was diminished. I attribute this to the tie rods now being parallel to the road, instead of at an angle they were with the zero offset Prime wheels.

Also, I went with Michelin LTX MS2 tires, they have a reputation of a better ride than the Bridgestone OE tires. I was running 65 PSI front and 80 rear.

I just returned from a trip to Yellowstone. All of the roads in Yellowstone and those on US 89 down to Brigham UT are up and down with sharp curves. Except for the need of new/better shocks, I was very surprised and pleased with the handling with a stock suspension. (Especially after reading of some of the handling problems others have experienced on this forum) Unless you consider 1/2" wider wheels and one size larger tires modified.

Thanks for the report. We're contemplating duplicating what you did. Do you think your factory supplied shocks are inadequate or could they just be old and tired?

[booster]

Originally Posted by Deano

Yes, most notably, bump steer was eliminated and lane wander was diminished. I attribute this to the tie rods now being parallel to the road, instead of at an angle they were with the zero offset Prime wheels.

Also, I went with Michelin LTX MS2 tires, they have a reputation of a better ride than the Bridgestone OE tires. I was running 65 PSI front and 80 rear.

I just returned from a trip to Yellowstone. All of the roads in Yellowstone and those on US 89 down to Brigham UT are up and down with sharp curves. Except for the need of new/better shocks, I was very surprised and pleased with the handling with a stock suspension. (Especially after reading of some of the handling problems others have experienced on this forum) Unless you consider 1/2" wider wheels and one size larger tires modified.

Always good to hear of successful changes, be they incremental or all at once.


My guess would be that the improvement in bump steer you have seen is not much related to tie rod position, because if you haven't changed the ride height (no other changes but wheels/tires, correct?) the tie rod positions won't really have changed except for a small amount due to different lever arm length from the tire contact point to the spring centerline. That can change the ride height a small amount. That said, the extra leverage on the spring also makes the wheel travel up further on bumps so all the steering geometry comes into play more, so you would get more bump steer even with exact proper tire rod location because of the extra travel. Weak shocks would allow even more travel.


What I think that I felt on our van when we had the aluminum wheels, probably could be called bump steer, but not in the classic definition. Bumps caused the van to steer itself, but so did puddles, and puddles don't really move the suspension up much. I think what was causing the "puddle steer" is that the tire contact point is moved away from the ball joint rotation centerline between them which is the scrub radius. When the tire hits anything that tries to move the wheel back horizontally, there is enough force with the increased leverage to physically move the steering parts all the way back to the steering wheel.


Classic bump steer can go either direction of turning depending on the tire rod position and other geometry in most cases and you generally don't feel much feedback into the steering wheel as it is mainly just the suspension parts moving around with the tie rod just going up and down. In the case of "puddle steer" you will always turn the same way and you will feel it trying to pull the steering wheel out of your hands. The direction it pulls to is determined by if the scrub radius is positive or negative. If it is positive you turn toward the wheel that is being pushed on, and if negative you turn away from it. Rear drive vehicles are normally positive and front drive vehicles negative.


The scrub radius is determined by the ball joint centerline angle (where that extended line hits the ground) and the wheel centeline, so changing the wheel offset can have major affect on the scrub radius. Moving back to the stock offset on wheels gets you much closer to zero scrub radius which makes the pull much less and also helps keep the tires from resisting turning and scuffing.

[booster]

Originally Posted by cruising7388

Thanks for the report. We're contemplating duplicating what you did. Do you think your factory supplied shocks are inadequate or could they just be old and tired?

IMO, the factory shocks are OK for the stock front springs, for a while. With stiffer springs or much more than 20K miles, they seem to get too soft for my liking. The change to Bilsteins really was a good on for us. Smoother on small bumps, much better control on big bumps.

[cruising7388]

Originally Posted by booster

IMO, the factory shocks are OK for the stock front springs, for a while. With stiffer springs or much more than 20K miles, they seem to get too soft for my liking. The change to Bilsteins really was a good on for us. Smoother on small bumps, much better control on big bumps.

The factory offset for the stock steel 6 1/2 inch rim is +28mm. Is it the same on the 9595221 7 inch rim? Does increasing the rim diameter call for a different optimum offset? I've fired off a couple of inquiries to GM parts suppliers for the offset spec for the wider rim but don't get a response.

[Deano]

Originally Posted by cruising7388

Thanks for the report. We're contemplating duplicating what you did. Do you think your factory supplied shocks are inadequate or could they just be old and tired?

1 14 years old
2 44000 miles
3 OE may not have been enough shock new. These Motor Homes are always heavily loaded, not just occasionally.

[Deano]

Booster,
You have explained correctly in great detail, much better than I could.
I tend to use a short, pointed statement.

[cruising7388]

Originally Posted by Deano

1 14 years old
2 44000 miles
3 OE may not have been enough shock new. These Motor Homes are always heavily loaded, not just occasionally.

Obviously the back end shocks of the 210 are exercised to the max but do the front shocks see significantly more load than a stock van?

[Deano]

I would think so, with a 20 gallon water tank under the driver and the grey tank under the passenger.

[booster]

Originally Posted by cruising7388

The factory offset for the stock steel 6 1/2 inch rim is +28mm. Is it the same on the 9595221 7 inch rim? Does increasing the rim diameter call for a different optimum offset? I've fired off a couple of inquiries to GM parts suppliers for the offset spec for the wider rim but don't get a response.

The concept of the big 3 specs for wheels is nearly guaranteed to confuse everyone the first few times they look at them, and many people every time they look at them


You really only need two of the specs to know everything that you need to know about a wheel, and that would be wheel width and offset. Backspace is used a lot because of what I mentioned earlier, wheels with the same backspace put the inside edge of the rim and tire at the same place on the vehicles, so you are pretty certain it won't hit anything. That is why the aftermarket uses backspace so much as they are selling alternative wheels.


What matters to handling is offset, and it is the amount that the center of the wheel width is offset from the mounting flange of the wheel. For the +28mm wheel that means the centerline of the width of the rim at the tire is 28mm inboard of the wheel mounting flange. The width of the rim doesn't matter because all you are looking at is the center, not the edges.


Wheel widith is used to get the right width wheel for the size of tires you are getting and has nothing to do with anything else, unless you want to calculate backspace to be able to look for possible interference.


The 7 inch steel Silverado wheel that has the 6 openings with scallops between them that have been linked will have the same offset as the stock steel wheels at +28mm. Because they are 1/2" wider than stock, they will have 1/4" more backspace.

[booster]

Originally Posted by cruising7388

Obviously the back end shocks of the 210 are exercised to the max but do the front shocks see significantly more load than a stock van?

The front of most of our vans is usually quite close to max weight of 4300# for the Chevies, with 210s lighter in the front than 190s because of all the rear overhang on the 210s. The front shocks get plenty of workout, especially with the too soft for the load stock front springs.

[cruising7388]

Originally Posted by booster

The 7 inch steel Silverado wheel that has the 6 openings with scallops between them that have been linked will have the same offset as the stock steel wheels at +28mm. Because they are 1/2" wider than stock, they will have 1/4" more backspace.

I'm having trouble visualizing this. Doesn't this pictorial indicate that for a wider wheel you would want less back spacing rather than more?

https://www.autoanything.com/wheels-...el-backspacing

[booster]

Originally Posted by cruising7388

I'm having trouble visualizing this. Doesn't this pictorial indicate that for a wider wheel you would want less back spacing rather than more?

https://www.autoanything.com/wheels-...el-backspacing

As I mentioned in the earlier explanation. If you are only concerned with interference with a wide rim, then you would reduce backspace by 1/2 the rim width increase so the inside edge of the wheel was in the same place with wider rim.



In the case of the two Chevy wheels, the goal was to have the same offset as stock, so all the steering geometries stay the same as stock for optimum driveability. Before I bought the wider wheels and tires, I put our +28 offset 6.5" wide wheel spare tire on the front of the van and measured all the clearances to be as sure as possible that the extra 1/4" of rim and tire to the inboard side would not be an issue. I had a plan B of using a 1/4" wheel spacer if there did turn out to be anything I missed.


IMO, you always want to stay as close to the stock offset as possible, even when going to wider wheels. I would only move to the outboard side (less backspace, toward negative offset) if there were interference, as it can negatively affect the handling characteristics.

[booster]

Originally Posted by cruising7388

The factory offset for the stock steel 6 1/2 inch rim is +28mm. Is it the same on the 9595221 7 inch rim? Does increasing the rim diameter call for a different optimum offset? I've fired off a couple of inquiries to GM parts suppliers for the offset spec for the wider rim but don't get a response.

Rim diameter changes don't really make a difference in optimum offset, it is the outside diameter of the tire that does make a difference. A bigger diameter at the tires will move the scrub radius toward the negative side, which can be OK, good, or bad, depending on what the scrub radius is when you start.


I think if you look a Hubcap Haven, they will have an offset listed for the 7" wide 16" rim in question.


I just looked at Hubcap Haven, and they have most of the other offsets listed, but not for that wheel. By application all the other wheels for the same application as the one in question have +28mm offset, and that is what I had found in the past, and measured on the ones we bought.

[booster]

I was just digging around trying to find an "official" offset for the 9595221 wheels, and I stumbled across this site with them for sale.


https://www.enosmalls.top/car-truck-...im-p-19560.htm


This price at $35 is really low, in the range of 1/3-1/4 of everyone else, so it may be bogus, but also may be worth checking out if looking for these wheels. Also is free shipping


The website is kind of weird, looks like it was a fashion site that is now transitioning into an automotive site. Looks like french and english so may in Quebec?



They do Paypal, so Paypal would have some information on them.


All the social media links go to Bed, Bath, and Beyond. Looks mighty shady to me.

[cruising7388]

Originally Posted by booster

I was just digging around trying to find an "official" offset for the 9595221 wheels, and I stumbled across this site with them for sale.


https://www.enosmalls.top/car-truck-...im-p-19560.htm


This price at $35 is really low, in the range of 1/3-1/4 of everyone else, so it may be bogus, but also may be worth checking out if looking for these wheels. Also is free shipping


The website is kind of weird, looks like it was a fashion site that is now transitioning into an automotive site. Looks like french and english so may in Quebec?



They do Paypal, so Paypal would have some information on them.


All the social media links go to Bed, Bath, and Beyond. Looks mighty shady to me.

It does look strange for a fashion design website to be selling these wheels.

https://www.trudshop.xyz/16x7034-fac...00-p-13574.htm

As far as I can tell, an equivalent part number for 9595221 is STL05198U20 but when they are Googled, you get a different spectrum of vendors with the different part numbers.

It looks like if I want brand new factory rims it will run about $200 per copy with total freight running $108 - 160 depending on the vendor. As you indicate there are vendors selling them all the way down to 1/4 of that but they are described as used, or reconditioned or refurbished or re-manufactured and as far as I know there aren't any objective standards for meeting these respective descriptions.

Going for used rims in good condition seems like an economical move and if all that's involved is some repainting, that doesn't seem like a big deal. But if the wheel has been dented and whacked out of true, while I may have bought a wheel, what I'll actually have is a boat anchor.

[cruising7388]

Originally Posted by booster

I just looked at Hubcap Haven, and they have most of the other offsets listed, but not for that wheel. By application all the other wheels for the same application as the one in question have +28mm offset, and that is what I had found in the past, and measured on the ones we bought.

I queried GM Parts direct regarding this but all I got back was the equivalent of a blank stare:

Hi Cruising7388,

Thanks for choosing GMpartsdirect.com.

We are not General Motors Corporation. We are a General Motors dealer selling new (and GM remanufactured) original equipment GM parts on the Internet.

The current licensed General Motors parts catalog does not provide that information.

Please accept our sincerest apology for any inconvenience this may cause.

Sincerely,
Floyd

Your customer service agent for
www.GMPartsDirect.com

Ticket: https://flowauto.freshdesk.com/helpdesk/tickets/13883

On Thu, 6 Sep at 5:25 PM , Cruising7388 <cruising7388@aol.com> wrote:
What is the offset incorporated into the 9595221 wheel?

[booster]

The wheels we got were reconditioned and were in excellent shape. They came from a southern "recycler" associated with Keystone Products, and were claimed to be new takeoffs, which happens quite a lot with truck wheels as lots of folks want different wheels.



There is a used part condition scale that is letter grade.


It goes from new, to very rough, several of the wheel sites I looked at listed the scale explanation for the ratings.


As long as steel wheels are not from salty areas, they would tend to be in quite good shape, likely much better than aluminum ones. I would not get reconditioned chrome ones, which are still available new, it appears.

[cruising7388]

Originally Posted by booster

As long as steel wheels are not from salty areas, they would tend to be in quite good shape, likely much better than aluminum ones. I would not get reconditioned chrome ones, which are still available new, it appears.

Are the chrome wheels actually chromed or are they just painted wheels that come with a mechanically attached chrome plated skin?

[booster]

Originally Posted by cruising7388

Are the chrome wheels actually chromed or are they just painted wheels that come with a mechanically attached chrome plated skin?

My guess would be that it is a crimp on chrome cover, as they aren't a lot more expensive than the plain ones.