Suspension

[Last Indian]

This post will take quite some time to step through if you folks have an interested. Many of the things done to the Indian were to improve its aesthetics as well as its performance, both power & handling. Yet the single thing that motivated me after I sold my beloved “69”Z was handling!

No car ever driven by me handled like the Z! I have raced cares since I was 14. I have had the privilege to race ¼ mile, stock car, road courses like Nelson’s ledges & many others around the country. I have even been fortunate enough to be a small part of a NASCAR project because of the job I did. There is no doubt in my mind there are way better, but for a plain Jane run of the mill, factory car, the Z, after all the mods that were done to it was untouchable by comparison.
So that’s what motivated me! To see if that same ideology could be accomplished with an FWD. I’m not talking drifting, or trash can exhaust, but honest hard, powering through, laid down flat cornering with a car that has a stance that looks the part of a muscle car! Not one scrapping its belly on the ground. That was my edict!
So what follows is a complete restructuring of a FWD. moving its weight, changing its weight! Changing its CG. Changing it RC. Changing it track widths. Changing possibly everything you thought impossible to change. In many cases literally gutting everything that you think of when you look to build your FWD.

So the very first action was to start changing the weight distribution. While this was the first action it took place over a extended period of time & modifications because many things had to happen to complete this endeavor. One change requires another, sometimes those changes resulted in the need for structural changes.
So #1! Relocate the battery to the trunk! This action alone took the equivalent of more than 90 pounds out of the front, which is above CG. Also the battery is set in a fulcrum effect on the front suspension, I.E. it has a mechanical leverage over the front suspension, as in 1 pound of weight has the equivalent effect of 3 pounds on the suspension as an example. When moved, a 25 pound gel mat battery was used & moved to the trunk below CG & slightly rearward of the rear suspension. Giving just a bit more weight effect to the battery.

 

Some bling for the front cover

[Robert]

I’ve never considered relocating the battery under the spare tire before—I’ve always moved it to the trunk in the past, but never thought of that spot. That’s a really clean setup! I’ll definitely give it a try on my TGP once I get back to that project. Thanks for sharing tips like this; it’s extremely helpful to the community and not something you see very often.

 

[Last Indian]

I’ve never considered relocating the battery under the spare tire before—I’ve always moved it to the trunk in the past, but never thought of that spot. That’s a really clean setup! I’ll definitely give it a try on my TGP once I get back to that project. Thanks for sharing tips like this; it’s extremely helpful to the community and not something you see very often.

Actually I have a word doc that describes in detail the installation. I made it for a friend a few years ago. I can also include the drawing of the adapters I made for the Odyssey PC925. This keeps the profile very tight & low under the spare. I’ll also show the cover I made for the positive attaching post to keep it protected. As well as the final finished view of the spare tire.

 

[Robert]

Would you mind if I use this type of information you share on the main website when I get to writing up the guides and stuff like that?

 

[Last Indian]

Would you mind if I use this type of information you share on the main website when I get to writing up the guides and stuff like that?

You are more than welcome to use any or all as you need to. I post what I do in part to share with those that wish to learn, to see what could be or to inspire if I can! I have always viewed the field of automotive mechanics to be one of the greatest drivers of innovation.

 

[Last Indian]

#2 was to add 40 pounds to the rear impact bar. Again, because the location of the 40#s is below CG & more than 45” from the rear axle centerline, this increases to the equivalent of 170 pounds. Additionally the rear impact bar was filled with structural urethane foam. This added another 6 pounds, but again this just at CG & amplified out to roughly 17 pounds.

Likewise when the battery was removed from the front, the front impact bar was gutted as much as possible! I.E. 2” diameter holes were bored through the two parallel channels sequentially removing the equivalent of approximately 20 pound when allowing for the fulcrum leverage effect.

 

[gs_geoff]

The inner Colin Chapman in me cringes at adding weight but this is actually badass. Someday I'm going to do the aluminum front cradle swap when I need new motor mounts, shaves 27lbs off the front end. Would love to relocate the battery like that as well.

 

[Last Indian]

The inner Colin Chapman in me cringes at adding weight but this is actually badass. Someday I'm going to do the aluminum front cradle swap when I need new motor mounts, shaves 27lbs off the front end. Would love to relocate the battery like that as well.

Trust me I hear you! But in a factory OEM FWD there are few option. The aluminum frame is one choice, but I have had some extensive experience with that frame in testing & it just won’t hold up under rigorous handling loads! The frames crack. Part of the problem was GM used the wrong alloy of aluminum & to thin of a gage. For a normal use, no hard cornering, no big sway bars, no lots of the adds I made & use; than the aluminum frame is ok! Stay tuned some of these upgrades may make you go slack jawed.

 

[Last Indian]

These pictures don’t detail the specific changes, but maybe they give you a hint as to what might come. Or maybe no?

 

[Last Indian]

So without getting to technical & lengthy, it goes like this. To effectively increase handling you must lower the CG, raise the RC & weight distribution needs to be 50/50 if possible or as close as possible. So the first thing you would always prefer is to lighten the car where needed, but when you can’t you move the weight around and where necessary you add some, thus was the case here. Than you look to increase the track widths & last modify the suspension components to take advantage of those changes.

225 lbs. was added to the Indian and all but 15lbs. of it was at or below wheel centerline. The equivalent of 90lbs was removed from the front nose area and relocated to the rear of the car, again below original CG. 40 lbs was added to the rear impact bar. Part of the weight redistribution was the relocation of the battery to the trunk spare tire well. Additionally the entire frame structure and dead spaces (lower firewall & rear cavity structure) were filled with structural urethane foam, contributing 22 lbs of the 225.The rear suspension carrier was reenforced to reduce flex in hard cornering, extra large lateral bars & trailing arms were installed. Redesigned upper rear strut mounts. Redesigned front lower A-arms to reduce torque steer and increase power transfer to the ground. Front struts components redesigned for increased corner stability & power transfer through better spring function. Heavy duty police package springs front & rear were installed. Upper strut bearings replaced with industrial grade pieces, better responsiveness and smoother wheel control & stability. Both front and rear sway bars were replaced with solid ZZP pieces! Their end links were replaced with my design. The front bar was replaced with a solid 34mm bar with larger diameter, shorter and stiffer end links. While the rear bar was replaced with a solid 25 mm diameter bar and a redesigned set of end links as well. Both sets of end links make a significant improvement over the OEM units as they make the bars do what they were designed to do, prevent body roll and keep the wheels planted on the ground.

 

[Last Indian]

In the picture in the previous post the new custom transverse makes all the difference in keeping the lower portion of the suspension from moving other than in up & down rotation! As should be the original intent! This also eliminates these lower components from adding to torque steer. It is also a huge improvement from a safety perspective as the design can not pull apart!
Likewise the gusseting of the rear suspension carrier makes a huge impact on keeping the lateral bars in place. Preventing the boss area of the carrier from flexing.

 

[Last Indian]

Filling all structural void space with structural urethane foam is somewhat time consuming because of how this process has to progress, but in the end well worth it! The stiffening, I.E. mechanical resonance, of the entire substructure improved substantially.
With these basic improvements to the substructure done I moved to suspension! Here there are changes I don’t believe anyone has ever made or even suggest, to my knowledge.

Let me start by saying the the McPherson strut is one stupid idea! It may work for pumping out cars faster than a double wish bone, but it sucks as a true suspension. That said, without a complete, new, from the ground up frame structure build we have to live with it. The OEM strut is a very weak component! One, the strut shaft is much to small to support any real aggressive handling, just way to much flex! Think about it! The entire weight of the car body is on one end of the 5/8 diameter 12” long strut shaft & all the of the subframe, engine, transaxle & suspension is on the other! They are literally trying to bend, shear & break that shaft! A quick math calculation of the section modulus & the shear modulus & one can see that the OEM shaft diameter can’t handle the acceleration of weight the front delivers without affecting the front components, thus changing their alignment! Which most often results in torque steer! Than the upper components of the strut assembly are junk! All plastic! Again way to much flex! So the overview pictures of some of those changes are previously shown.

Some of the reasons these platforms exhibit bad torque steer is the shaft diameter of the strut & the ridiculous transverse A-arm mount! It’s not the only reason, but they are pretty substantial in their effect.

Those of you who have rebuilt the front suspension completely know what these components are & how junky the factory plastic pieces are. Also how distorted they are upon disassemble! The addition of the industrial grade thrust bearing can’t be done without the building of the other aluminum components. I can tell you first hand the change in the front suspension from a feel perspective is astounding.

 

[Last Indian]

Once again for those that wish to attempt to make these upgrades I am providing my prints. Both for the bearings upgrade as well as the transverse mount for the A-arm. Bear in mind that the upper bearing housing is in plastic for several reasons. One, it’s trapped between the upper bearing plate, which is steel & the steel thrust bearing plate. Two it really only acts as a locator & three it needs to be of a material that can contact the aluminum bearing support housing without galling, because it basically acts as a dust/moisture cover.

 

[Last Indian]

A few more pictures to show the strut build & the lower A-arm transverse bearing modification upgrades!

 

[Last Indian]

Now as I previously said my front bar is a huge 34mm solid bar & that can make a improvement in handling, but, & it’s a big but! If you change only the bar & use the original end links you’re wasting your money! The main key are the end links! Fact! If you left the original front bar in place & replaced the end links with my design you would effectively see the same results as buying the solid 34mm bar & using the factory style end links. This is just pure physics!

The purpose of a sway bar is literally twist a round bar around it’s circumference between two wheels! The weaker the end links, the more flex they have, than the less rotational movement there is in the bar! So to make the end links more effective they have to be more ridged!

The factory setup is too long! The plastic sleeve that separates one end of bushings from the other is to flexible! The through bolt is to small, & the rubber bushings are too soft! So increasing the bolt from 5/16 to 3/8 is step one. That’s a 45% increase in circumference! Almost half again as big as the factory. You also need to shorten the bolt length from its current length to just enough to accommodate the new configuration. Next the intermediate spacer needs shortened & made from stainless, aluminum, steel etc. Then replace the two inner rubber bushings with urethane bushings! You can find these with the same outside configuration, but with a 3/8 ID hole. Then the top & bottom rubber bushings need replaced with very short nylon bushings.

Now, this configuration works very very well! So much so that it would unscrew the top nut. So I used a double jam nut! But even that would not keep the nuts from unscrewing. So I finally had to cotter pin the top nut & that resulted in being very effective! The effect of this design is difficult to express, but this design coupled with the solid 34mm bar & KYB AGX struts plus the rear mods I will explain soon, will generate corners so flat you better glue your butt to the seat; literally!

 

[ThatSlow.W204]

Now as I previously said my front bar is a huge 34mm solid bar & that can make a improvement in handling, but, & it’s a big but! If you change only the bar & use the original end links you’re wasting your money! The main key are the end links! Fact! If you left the original front bar in place & replaced the end links with my design you would effectively see the same results as buying the solid 34mm bar & using the factory style end links. This is just pure physics!

The purpose of a sway bar is literally twist a round bar around it’s circumference between two wheels! The weaker the end links, the more flex they have, than the less rotational movement there is in the bar! So to make the end links more effective they have to be more ridged!

The factory setup is too long! The plastic sleeve that separates one end of bushings from the other is to flexible! The through bolt is to small, & the rubber bushings are too soft! So increasing the bolt from 5/16 to 3/8 is step one. That’s a 45% increase in circumference! Almost half again as big as the factory. You also need to shorten the bolt length from its current length to just enough to accommodate the new configuration. Next the intermediate spacer needs shortened & made from stainless, aluminum, steel etc. Then replace the two inner rubber bushings with urethane bushings! You can find these with the same outside configuration, but with a 3/8 ID hole. Then the top & bottom rubber bushings need replaced with very short nylon bushings.

Now, this configuration works very very well! So much so that it would unscrew the top nut. So I used a double jam nut! But even that would not keep the nuts from unscrewing. So I finally had to cotter pin the top nut & that resulted in being very effective! The effect of this design is difficult to express, but this design coupled with the solid 34mm bar & KYB AGX struts plus the rear mods I will explain soon, will generate corners so flat you better glue your butt to the seat; literally!

very nice, i made myself some custom end links when i did my LFX swap because the factory ones where junk lol

 

[PierreNotPear]

This entire thread is mindblowing, but there's something I have to know. Is your day job something in the world of engineering? The way you write up your posts sounds just like the lectures over strengths and statics I'm spending my time sitting through

 

[Last Indian]

This entire thread is mindblowing, but there's something I have to know. Is your day job something in the world of engineering? The way you write up your posts sounds just like the lectures over strengths and statics I'm spending my time sitting through

Well to answer your question first. My day job is retired! But in a previous life yes, kind of. I spent 40 years with one of the largest specialty chemical corporations in the world. There would be very little that you buy for any petroleum based product, car, truck, big rig, 2 cycle, 4 stroke, engine, transmission, gear box you name it, as well as other market segments.That wouldn’t have our products in the fluid.

I worked on the corporate side in new product development. I was their all in one designer, developer, mechanical/applications engineer/design engineer. Sounds crazy & a bunch of bull, I know! What’s even crazier is I have no degree! I started there as a research/prototype machinist! Within one year a large number of the mechanical test engineers would come to me to solve their problems. Long story short, the Vice President of research interfaced with me on an extremely crucial project that involved millions of dollars with Fords factory fill & I resolved it in a week. As they say the rest is history!

 

[Last Indian]

While I’m on the subject of cornering I would like to interject something else.

On the interior post I made, I showed a custom steering wheel. This is about the impact of steering wheel size.

Now the factory wheel is a 15” wheel. When I built my custom wheel I reduced it to 13”! That wasn’t just for looks! It has a functional purpose rooted in physics! The cord of a 15” wheel is 47.124”. The cord of a 13” wheel is 40.84” that’s 6.24” shorter cord. That is pretty big. What does this mean? Well a typical 2 lane 90 degree turn covers about 70’ for a normal turn, I.E. not an aggressive cornering move. Call it a street elbow not a right angle. At 25 mph that will take right around 1.91 seconds to complete. A 15” wheel needs nearly all of that time to negotiate the corner at a normal rate for turning the steering wheel, again I.E. not rushing to turn the wheel, but also no time just stagnant. Under the same identical conditions a 13” wheel would require actually slowing down the turn speed of the steering wheel! Meaning there will be stagnant moments. So in comparison because of the shorter cord, 6.24” shorter, it would require only 1.26 seconds to turn the steering wheel the amount needed to complete the turn as opposed to 1.91 seconds! So in this way you see why you would have to slow down the rate at which you turn the wheel.

Now if by chance you want to turn a sharper more aggressive “right angle” corner, which would actually reduce the length of the turn to something much less than 70’! Yet you can see how much more time you have to complete the turn of the steering wheel without losing control due to rushing the turn! It’s not that it makes the steering quicker, but it actually changes a key factor in the relationship of the steering ratio that is almost always overlooked!

 

[ThatSlow.W204]

Very very cool steering wheel! that is a very cool mod man! never seen anybody do that much effort, usually people just toss a cheap aftermarket one on haha