Front Sway Bar Links

[jojobafanzi]

I replaced my front sway bar bushings and end links in my quest to improve the handling and feel of the vehicle. I started with the two bushings on my 2017 Versatile 170. They didn't look bad but I changed them out for Polyurethane Energy Suspension 9.5168. The Poly bushings are a fraction in thickness but much wider compared to the OEM rubber. I could immediately feel better road manners from the 170V. The sway bar end links looked fine with no cracks or deformities but I ordered replacements anyway. I installed the Moog k700537 Polyurethane end links. This final upgrade perhaps should have been the first upgrade when I replaced the shocks. Absolutely good money spent. Easy to install and very inexpensive. I highly recommend this upgrade. Cheers! Joe

[phantomjock]

Chevy 2500 I assume? Thanks for the "Links." I wasn't looking for an excuse to crawl under the front end again! Red or Black?

I note the Moog K700537 is listed for the Ford Mustang. Amazon says it fits. I shoulda' had these when I made the "Lift." Oh well. It will be nice to add them now and put "pencils down" on the front end.

Cheers - Jim

[booster]

Originally Posted by phantomjock

Chevy 2500 I assume? Thanks for the "Links." I wasn't looking for an excuse to crawl under the front end again! Red or Black?

I note the Moog K700537 is listed for the Ford Mustang. Amazon says it fits. I shoulda' had these when I made the "Lift." Oh well. It will be nice to add them now and put "pencils down" on the front end.

Cheers - Jim

It is interesting on the end links being that much better than stock unless the stockers were old school rubber ones.


By 2007 GM had switched to what are probably hard polyethylene end links that are very hard and incompressible so would very likely to give handling similar to aftermarket urethane. The privot bushings, I don't recall what they are made of, I will have to look.


With the end links, IMO, it is important to have the van level and on the ground when you tighten the links, so the bar doesn't wind up preloading the suspension (unless you want it to because of uneven weight distribution).

[jojobafanzi]

Originally Posted by phantomjock

Chevy 2500 I assume? Thanks for the "Links." I wasn't looking for an excuse to crawl under the front end again! Red or Black?

I note the Moog K700537 is listed for the Ford Mustang. Amazon says it fits. I shoulda' had these when I made the "Lift." Oh well. It will be nice to add them now and put "pencils down" on the front end.

Cheers - Jim

My 170V is a 2500. The bushings I ordered are black but I really don't care about color. I'm sure these links fit many applications.

[jojobafanzi]

Originally Posted by booster

It is interesting on the end links being that much better than stock unless the stockers were old school rubber ones.


By 2007 GM had switched to what are probably hard polyethylene end links that are very hard and incompressible so would very likely to give handling similar to aftermarket urethane. The privot bushings, I don't recall what they are made of, I will have to look.


With the end links, IMO, it is important to have the van level and on the ground when you tighten the links, so the bar doesn't wind up preloading the suspension (unless you want it to because of uneven weight distribution).

I'm not sure what the OEM links are made of but they look like and feel like hard rubber. The OEM links can only be compressed until the bolt runs out of thread in the end nut. The aftermarket Moog instructions require to hand tighten until resistance is felt and then turn 2 more complete turns on the nut. There will be several threads exposed beyond the nut. It can be overtightened and I think if that happened, the bushings would become damaged. I followed the instructions. I had the vehicle weighed and got different numbers on each rear wheel. When the suspension is working and during breaking, when weight of the vehicle moves from rear axle to forward axle and back to rear axle, the force transfer will move at a diagonal. That is what led me to the front sway bar and its components. The front sway bar is larger in diameter than the rear and that makes sense. Without it, the vehicle would want to roll over while breaking in a turn. To me, all that rubber up front and the uneven weight distribution was not right. The vehicle felt like it was wiggling in the front. Every shop and myself included said the front end was tight. Every modification I did made improvements in the ride but the little wiggle was still there. I conclude that the front sway bar components just had way too much room to move instead of relying on the torsion of the bar to do its job. So problem is solved after about $5k spent. I am grateful the issue is solved. The van is a pleasure to drive now and all the upgrades I did to the suspension may save my ass on the highway one day. So to recap.... Bilstein Shocks, New tires, proper alignment and front sway bar component upgrade should be the absolute first thing that should be done to these vans. Next I would recommend rear sway bar. Not sure if the trac bar is necessary but I can say that also made an improvement. Right now I'm glad I did all the modifications and the van handles like a sports car in turns.

[booster]

Did you measure the actual diameter of the bar in the front of the van?



I ask because, I reduced the diameter of the front bar in ours and all the sizes were metric diameters. The lighter vans in 1500 and 2500 models used a smaller bar that I got and put in to improve the directional stability a bit. I don't recall the size, so I will have to go out and measure it.


All the bushings listed for 2500 and 3500 vans on Rock Auto are shown at 33mm which is 1.30" or 32.5mm which is 1.28". A 1 3/8" urethane bushing will be pretty loose on both of those and a 1 5/16" bushing would by much closer. Urethane bushings are supposed to run with a little interference even for best performance. That is why you need to grease them to prevent squeaking.


Another oddity is that the replacement swaybar kit is listed as 29mm, so that must be the lighter duty van one and it is now covering all vans as replacements. It is probably what I put in at 1.14"


It is time for me to check all the swaybar links and bushings anyway, and grease the rear urethane ones, as we have had one front link fall off in the past.

[booster]

Weight transfer does not happen diagonally under braking, in goes rear to front only in the direction of travel. The van is basically rotating around the center of gravity and how much downforce you get it the front is dependent on the location of the center of gravity in any particular van


If you have mismatched rear wheel weights the CG will be lightly moved over toward the heavier side and that offset will transfer straight to front as slightly more load on the same side wheel in front, as I understand it.


When the van is stationary the springing and accuracy of build can make a diagonal weight difference on opposite ends, though.


Rear drive cars with the style of steering that is in the vans all exhibit a bit of squirm on brake application as the traction on each side of the van is never exactly equal. It is normally a quick squirm when the brakes first apply and goes away once the brakes start to load force. How much that squirm is relates to how the vehicle is aligned and the scrub radius direction and amount is a big factor in determining how much it squirms. That is why vehicles that move the wheels outboard with high negative offset wheels will see more squirm than they did with stock wheels.

[jojobafanzi]

Originally Posted by booster

Did you measure the actual diameter of the bar in the front of the van?




It is time for me to check all the swaybar links and bushings anyway, and grease the rear urethane ones, as we have had one front link fall off in the past.

What grease do you use on your sway bar bushings? Are you using polyurethane bushings?

[jojobafanzi]

Originally Posted by booster

Did you measure the actual diameter of the bar in the front of the van?



I ask because, I reduced the diameter of the front bar in ours and all the sizes were metric diameters. The lighter vans in 1500 and 2500 models used a smaller bar that I got and put in to improve the directional stability a bit. I don't recall the size, so I will have to go out and measure it.


All the bushings listed for 2500 and 3500 vans on Rock Auto are shown at 33mm which is 1.30" or 32.5mm which is 1.28". A 1 3/8" urethane bushing will be pretty loose on both of those and a 1 5/16" bushing would by much closer. Urethane bushings are supposed to run with a little interference even for best performance. That is why you need to grease them to prevent squeaking.


Another oddity is that the replacement swaybar kit is listed as 29mm, so that must be the lighter duty van one and it is now covering all vans as replacements. It is probably what I put in at 1.14"


It is time for me to check all the swaybar links and bushings anyway, and grease the rear urethane ones, as we have had one front link fall off in the past.

My front sway bar is 35mm diameter. The rear is about 34mm. I used 1-3/8" bushings for the front and ordered 1-5/16" for the rear bar yesterday. The rear sway bar was supposed to have polyurethane bushings but the shop installed rubber. Those rubber bushings are identical to the bushings I removed from the front sway bar. My better half is telling me to leave the rear bushings alone because the van drives great now. She said if it works, don't F... with it.

[booster]

Originally Posted by jojobafanzi

What grease do you use on your sway bar bushings? Are you using polyurethane bushings?

I like silicone grease on them if possible, but you need an extra grease gun that way to keep it separate. That is what I used when I assembled them on the rear quite a while ago, and refreshed a bit later on when I changed the rear axle. No squeaks so have left it alone. They have grease fittings but on tight bushing grease won't get to all areas as there are no channels for it to move in. If they are loose the grease will move around, but so will the bar which is what you don't want.


I only have urethane in the rear, as that is the end you firm up to get the front to gain more traction. If I put urethane in the front to firm it up more, it would actually increase understeer a bit. I went to the smaller bar to reduce the understeer by softening the sway bar force.

[jojobafanzi]

Originally Posted by booster

I like silicone grease on them if possible, but you need an extra grease gun that way to keep it separate. That is what I used when I assembled them on the rear quite a while ago, and refreshed a bit later on when I changed the rear axle. No squeaks so have left it alone. They have grease fittings but on tight bushing grease won't get to all areas as there are no channels for it to move in. If they are loose the grease will move around, but so will the bar which is what you don't want.


I only have urethane in the rear, as that is the end you firm up to get the front to gain more traction. If I put urethane in the front to firm it up more, it would actually increase understeer a bit. I went to the smaller bar to reduce the understeer by softening the sway bar force.

I think I will throw the new bushings in the trunk when they arrive and leave the vehicle alone.

[booster]

Originally Posted by jojobafanzi

My front sway bar is 35mm diameter. The rear is about 34mm. I used 1-3/8" bushings for the front and ordered 1-5/16" for the rear bar yesterday. The rear sway bar was supposed to have polyurethane bushings but the shop installed rubber. Those rubber bushings are identical to the bushings I removed from the front sway bar. My better half is telling me to leave the rear bushings alone because the van drives great now. She said if it works, don't F... with it.

That is interesting as I also looked at Advance auto and they are also selling all 1 5/16" diameter bushings for the vans. Is it the stock bar, to best of your knowledge of the history of the van?

[jojobafanzi]

Originally Posted by booster

That is interesting as I also looked at Advance auto and they are also selling all 1 5/16" diameter bushings for the vans. Is it the stock bar, to best of your knowledge of the history of the van?

Yes, to the best of my knowledge, the front sway bar is original and is 35mm. The rear bar is GM and is about 33.8mm.

[jojobafanzi]

Originally Posted by booster

Weight transfer does not happen diagonally under braking, in goes rear to front only in the direction of travel. The van is basically rotating around the center of gravity and how much downforce you get it the front is dependent on the location of the center of gravity in any particular van


If you have mismatched rear wheel weights the CG will be lightly moved over toward the heavier side and that offset will transfer straight to front as slightly more load on the same side wheel in front, as I understand it.


When the van is stationary the springing and accuracy of build can make a diagonal weight difference on opposite ends, though.


Rear drive cars with the style of steering that is in the vans all exhibit a bit of squirm on brake application as the traction on each side of the van is never exactly equal. It is normally a quick squirm when the brakes first apply and goes away once the brakes start to load force. How much that squirm is relates to how the vehicle is aligned and the scrub radius direction and amount is a big factor in determining how much it squirms. That is why vehicles that move the wheels outboard with high negative offset wheels will see more squirm than they did with stock wheels.

Under normal driving, the suspension is always moving. If the load on the rear springs is not equal like our vans, then the springs will move at a different frequency. The spring with more load will cycle at a slower rate. That is probably what would causing the sway and the miserable ride. Once I tightened up the front, the front sway bar started doing its job.

[booster]

Originally Posted by jojobafanzi

Under normal driving, the suspension is always moving. If the load on the rear springs is not equal like our vans, then the springs will move at a different frequency. The spring with more load will cycle at a slower rate. That is probably what would causing the sway and the miserable ride. Once I tightened up the front, the front sway bar started doing its job.

I guess I miss the point, as the load on the spring doesn't really affect the speed of the reaction to an input, like a bump. The spring rate and unsprung weight would most likely determine the reaction and would be tempered in all cases by the shocks. Yes, spring rate does change slightly with compression, but not really enough to be a big factor.


In the van, on single rear wheel bumps the rear axle will "rear steer" as the axle doesn't move straight up and down as it rotates around the front spring eye separately on each side.


It is probably more likely, I think, that your old bushings and more so the endlink bushings if they were quite loose were putting a different preload in the front bar. I have tested a bit on this, and have been able to move individual loads from side to side by adjusting the endlinks to put preload on it in one direction. It is very common to have the end links not hit the bar without the top nuts tightened. That difference when tightened puts preload on the bars. It is really common if the links were snugged down with the wheels hanging and not on the ground with full weight on them. Whatever it was you are happy with the results so it doesn't matter much in the big picture. It could be that you prefer to have some more understeer in the handling, many people do, which slows the steering reaction to inputs a bit and also requires slightly bigger inputs. Very quick responding, low understeer will twitchy and will constantly be getting over correcting, make it feel unsettled in driving.

[jojobafanzi]

Originally Posted by booster

Whatever it was you are happy with the results so it doesn't matter much in the big picture. It could be that you prefer to have some more understeer in the handling, many people do, which slows the steering reaction to inputs a bit and also requires slightly bigger inputs. Very quick responding, low understeer will twitchy and will constantly be getting over correcting, make it feel unsettled in driving.

It's fixed and a pleasure to drive. I appreciate your input and guidance. Thank you!