How to lower Aoshima Mazda RX7

[leon_s]

Hello guys, 

A little intro, I'm very new in auto modelling world and I'm interested to learn how to build one and also how to modify them.  

I just bought myself a Mazda RX7 series 4 made by Aoshima and I also bought a set of aftermarket wheels. So my plan is simple, lower it and put the aftermarket wheels on and hopefully I can make it as neat as possible. Since I just got the kit a couple of days ago, I haven:t had a chance to build it,  but I did look at the suspension part since I'm planning to lower it. Now here's my question. In this Aoshima kit, the wheels and brakes are fixed to the subframe. One lowering method I know is by cutting the spring shock assembly. But in the RX7, the setup is different. The brakes and wheels are fixed to the subframe. The srping and shock assembly is not part of the subframe. Can anyone help me with this? Is there any other method I can use to lower this kinda setup? Any tips are very much appreciated. 

I apologize for the lack of photos. If needed, I can post pics of the parts or the manual book

 

Thanks in advance 

[Ace-Garageguy]

Photos of what you have would definitely help. I checked my shelf and all I have in stock is the Tamiya version.

One method that MAY work for you, if you're not concerned about doing it realistically, is to simply cut the mounting pins for the wheels or axles off of the subframes (or spindles / struts, depending on how they're made) and move them UP the amount you want the car to go DOWN. This involves very careful measuring to hit it right the first time, and you should mock up the car (dry-assemble) with it at stock ride-height, but on the new wheels you have. 

Measure the ground clearance you have that way, then take the suspension bits out and mock up the car over the new wheels the height you WANT it to sit. Measure the ground clearance there too.

The difference between the two measurements is the exact amount you need to raise the axle stubs or pins. Be SURE to measure both ends, as good-looking lowering usually tends to have slightly different ride-heights front and rear.

One problem with lowering cars, even real cars, is that you can run into all kinds of clearance problems, with your wheels or tires or both interfering with the inside of your body, or suspension and steering parts.

 

Edited October 23, 2015 by Ace-Garageguy

[leon_s]

[Twokidsnosleep]

Ya, I can see what you are having trouble with there..... have to cut the A arms and move them up but you have nothing to put them onto with the way it is moulded 

Interested in hearing what someone smarter than I can figure out, sorry man

Edited October 21, 2015 by Twokidsnosleep

[leon_s]

Sorry, didn't know how to add comments at first

 

Thanks for replies guys

As for realism, i dont care too much as long as ithere is some suspension 

 

Any other takers? Any opinions are appreciated 

[Ace-Garageguy]

Let's start with the front end, because it's the easiest to get to look full-scale correct.

From your photos, it appears that Aoshima has intended the front wheels to be pose-able, as to steering angle. It looks like the spindles are intended to mount in the holes on the upper and lower control arms.

You'll notice the upper control arm (when the chassis is sitting upright) has a cylindrical "boss" at the end the lower control arm lacks. The easiest way to get lowering here (looks like you can get between 1/16 and 1/8 inch) would be to cut the boss off the top arm, squarely and neatly, and use small-diameter plastic tube to add a boss of identical height to the lower arm. This will raise the spindle relative to the vehicle and lower the car.

Without seeing photos of the front spindles, I can still assume you could cut the stub-axle off of them and relocate it higher, similar to what I described in my post above. That's the easiest way by far, if it's possible.

------------------------------------------------

It looks like the easiest way to lower the rear is going to be to remove the "tab" on the upper control arm that sticks down into the brake disc / wheel backing plate. This will allow the axle to move up in the backing plate / control arm, relative to the chassis, and result in lowering the car. This will, unfortunately, place the backing plate well off-center relative to the wheel, so you may have some interference you'll have to fix by removing material from the backing plate where it touches the wheel.

If I were lowering this model, I'd glue the rear suspension together at the outboard ends, cut the backing plates off of the control arms, and relocate them upwards the amount I wanted to go lower...again, correcting any interference caused in the process. This method would leave the backing plates centered in the wheels.

-----------------------------------------------

In any event, think through what you're trying to accomplish, and how moving or modifying one thing will affect something else. Work slowly and measure carefully, and make drawings or notes to keep your measurements straight in your head.

 

 

Edited October 22, 2015 by Ace-Garageguy

[Twokidsnosleep]

Genius for the front ones

I was stuck in trying to move the hole control arm complex up.

Rears are a little tougher

[Kennyboy]

How about on the front just cutting the mounting pin off the spindle, drilling a hole in the spindle, and running a new peg for the wheel to mount on to. You can drill it at any height along the spindle cylinder to lower the front end without "monkeying" with the control arms.

[Ace-Garageguy]

How about on the front just cutting the mounting pin off the spindle, drilling a hole in the spindle, and running a new peg for the wheel to mount on to. You can drill it at any height along the spindle cylinder to lower the front end without "monkeying" with the control arms.

That's what I always suggest first, and suggested in my first answer to the OP's question....and again in my second answer to the question.

Quoting myself:

"Without seeing photos of the front spindles, I can still assume you could cut the stub-axle off of them and relocate it higher, similar to what I described in my post above. That's the easiest way by far, if it's possible."

Edited October 23, 2015 by Ace-Garageguy

[Kennyboy]

That's what I always suggest first, and suggested in my first answer to the OP's question....and again in my second answer to the question.

Quoting myself:

"Without seeing photos of the front spindles, I can still assume you could cut the stub-axle off of them and relocate it higher, similar to what I described in my post above. That's the easiest way by far, if it's possible."

Sorry Bill, I should know better than to answer a topic on the day of the 4th 12 in a row. (12 hour day). At least we think alike in our solution. 

[Ace-Garageguy]

...At least we think alike in our solution. 

Great minds and all that...

[leon_s]

Let's start with the front end, because it's the easiest to get to look full-scale correct.

From your photos, it appears that Aoshima has intended the front wheels to be pose-able, as to steering angle. It looks like the spindles are intended to mount in the holes on the upper and lower control arms.

You'll notice the upper control arm (when the chassis is sitting upright) has a cylindrical "boss" at the end the lower control arm lacks. The easiest way to get lowering here (looks like you can get between 1/16 and 1/8 inch) would be to cut the boss off the top arm, squarely and neatly, and use small-diameter plastic tube to add a boss of identical height to the lower arm. This will raise the spindle relative to the vehicle and lower the car.

Without seeing photos of the front spindles, I can still assume you could cut the stub-axle off of them and relocate it higher, similar to what I described in my post above. That's the easiest way by far, if it's possible.

------------------------------------------------

It looks like the easiest way to lower the rear is going to be to remove the "tab" on the upper control arm that sticks down into the brake disc / wheel backing plate. This will allow the axle to move up in the backing plate / control arm, relative to the chassis, and result in lowering the car. This will, unfortunately, place the backing plate well off-center relative to the wheel, so you may have some interference you'll have to fix by removing material from the backing plate where it touches the wheel.

If I were lowering this model, I'd glue the rear suspension together at the outboard ends, cut the backing plates off of the control arms, and relocate them upwards the amount I wanted to go lower...again, correcting any interference caused in the process. This method would leave the backing plates centered in the wheels.

-----------------------------------------------

In any event, think through what you're trying to accomplish, and how moving or modifying one thing will affect something else. Work slowly and measure carefully, and make drawings or notes to keep your measurements straight in your head.

 

 

How about on the front just cutting the mounting pin off the spindle, drilling a hole in the spindle, and running a new peg for the wheel to mount on to. You can drill it at any height along the spindle cylinder to lower the front end without "monkeying" with the control arms.

Wow.. Awesome answers.. Thanks alot guys. Can't wait to give it a try. One question, can you please show me the 'spindles' you are referring to on the picture? Sorry for the stupid question 

[Ace-Garageguy]

... One question, can you please show me the 'spindles' you are referring to on the picture? Sorry for the stupid question 

The spindles don't show in any of your pictures.

They would be part of the parts that attach to the little holes in the ends of the front control arms, but I honestly don't know what those parts look like in this kit. If you can put up a picture of them snapped in place, we'll go from there.

QUESTION: The research I've done on this looks like the S4 cars had a lower control arm and a strut in front, not an upper control arm like your model pictures show. The later 3rd generation cars ('92 and up) DID have two front control arms.

S4   

This is what the real suspension looks like...a lower arm and a strut (the stock strut has been replaced with an upgraded adjustable coil-over type, but the basic design and function is the same)

.

Edited October 23, 2015 by Ace-Garageguy

[Kennyboy]

I am guessing that we are dealing with a 3rd generation here Bill. On the chassis shot above you can see the "92-15 RX7" which would make it a '92 efini RX7 or a '93 RX7 for u.s. market.

The '91 and down 2nd gens had a Macpherson type front suspension (like Bill explained above).

[Ace-Garageguy]

I am guessing that we are dealing with a 3rd generation here Bill. On the chassis shot above you can see the "92-15 RX7" which would make it a '92 efini RX7 or a '93 RX7 for u.s. market.

The '91 and down 2nd gens had a Macpherson type front suspension (like Bill explained above).

Yup. Found a shot of the underside of an Aoshima RX-7 that matches the model photos above here... http://www.modelcarsmag.com/forums/topic/104869-aoshima-rx7-veilside-fd3s/

and it's definitely a gen-3 car, which would make it at least an S5, I believe. Now we're getting somewhere.

     All we need is pix of the spindles.

EDIT: It appears Aoshima used the same chassis for the S4 car (below) with a different exhaust system.     http://www.modelcarsmag.com/forums/topic/89977-aoshima-rx-7-fc3s/       I don't know if this is correct or not in 1:1, but I DO know the front suspension is not the same in reality.

  Still need pix of the OP's spindles.

Edited October 24, 2015 by Ace-Garageguy

[mike 51]

On the Aoshima wheel kits I have the "spindles/pin"  is on the wheel itself (like Tamiya kits) with a hole/brake locator on the uprights that would be hard to move up or down..  

Also the off-set of modern wheels often put the a arms inside the wheels which limits how much it can be lowered as well.  

Anything more then a scale inch or two turns into a fairly big job of  reworking of the locations of the various suspension pieces...

 

Edited October 24, 2015 by mike 51

[Ace-Garageguy]

On the Aoshima wheel kits I have the "spindal/pin"  is on the wheel itself (like Tamiya kits).  

The off-set of modern wheels often put the a arms inside the wheels which limits how much it can be lowered as well.   Anything more then a scale inch or two turns into a big reworking of the locations of the various suspension pieces...

So...what snaps into the ends of the control arms on the OP's chassis, and allows the front wheels to steer like Ray's black & silver chassis above? What does it look like?

Edited October 24, 2015 by Ace-Garageguy

[mike 51]

I'm not sure on this particular kit but...I'm thinking its likely square in shape with with a raised portion to locate the brake rotors with a hole inside to mount the wheel , that has locatng pins (think ball joints) at the top and bottom. 

I don't think they look much like the "real" parts...maybe the poster will take a pic?

[Ace-Garageguy]

This is the Tamiya version    http://www.modelcarsmag.com/forums/topic/97063-back-with-an-rx-7/?page=1   (I have 2 here that I checked to be sure). The front suspension setup appears to be very similar to the Aoshima kit, with upper and lower front control arms that have holes in the ends.

  

This is it with the spindles / brakes assembled, and the spindle / brake units are fair approximations of the real thing...

I can't be sure from this shot, but it APPEARS that the front brake rotor and hub may be cast as a unit with the spindle. If that's the case with the Aoshima kit, simply sawing the rotor / hub off of the spindle and moving it UP relative to the spindle will lower the car...until, as you say, other interference makes problems.

 

 

 

Edited October 24, 2015 by Ace-Garageguy

[mike 51]

Yep assembled  the brake/spindle pieces look fine (but the spindle by itself not so much because of the brake locator)..

.but lowering it beyond a hair or two..would be a fairly big project by my standards (this being my point)   

Edited October 24, 2015 by mike 51

[Ace-Garageguy]

I just broke open a Tamiya kit to look at the front spindles. It's a simple matter to get 2-3 scale inches of lowering at the spindle by simply shaving off the tubular section that spigots into the brake hub, and replacing it with a piece of styrene tube of the same length, ID and OD, but raised on the remaining spindle material. This would allow the stock poly caps to be used as designed too.

NOTE: This is exactly the same geometry change as you get with a "dropped spindle" for a real car.

There is possible interference of the inner wheel rim with the "balljoint" on the lower control arm. That would be the limiting factor for lowering without relocating the arms...which really isn't that hard.

Still needing to see pix of the Aoshima setup though...

The Tamiya gen-3 RX-7 front spindles are in drawing 4 below, parts A13 and A14. 

Edited October 25, 2015 by Ace-Garageguy

[Kennyboy]

On the Tamiya instructions above, it looks like the spindle that mounts the brake rotor is offset top to bottom slightly. If that is the case, you can also flip the spindles upside down and switch which side they are mounted on. Just a thought.

I will have to check my stash tomorrow......I think I have the RE Amemiya RX7 race car kit from Aoshima down there.

Edited October 25, 2015 by Kennyboy

[leon_s]

Let's start with the front end, because it's the easiest to get to look full-scale correct.

From your photos, it appears that Aoshima has intended the front wheels to be pose-able, as to steering angle. It looks like the spindles are intended to mount in the holes on the upper and lower control arms.

You'll notice the upper control arm (when the chassis is sitting upright) has a cylindrical "boss" at the end the lower control arm lacks. The easiest way to get lowering here (looks like you can get between 1/16 and 1/8 inch) would be to cut the boss off the top arm, squarely and neatly, and use small-diameter plastic tube to add a boss of identical height to the lower arm. This will raise the spindle relative to the vehicle and lower the car.

Without seeing photos of the front spindles, I can still assume you could cut the stub-axle off of them and relocate it higher, similar to what I described in my post above. That's the easiest way by far, if it's possible.

------------------------------------------------

It looks like the easiest way to lower the rear is going to be to remove the "tab" on the upper control arm that sticks down into the brake disc / wheel backing plate. This will allow the axle to move up in the backing plate / control arm, relative to the chassis, and result in lowering the car. This will, unfortunately, place the backing plate well off-center relative to the wheel, so you may have some interference you'll have to fix by removing material from the backing plate where it touches the wheel.

If I were lowering this model, I'd glue the rear suspension together at the outboard ends, cut the backing plates off of the control arms, and relocate them upwards the amount I wanted to go lower...again, correcting any interference caused in the process. This method would leave the backing plates centered in the wheels.

-----------------------------------------------

In any event, think through what you're trying to accomplish, and how moving or modifying one thing will affect something else. Work slowly and measure carefully, and make drawings or notes to keep your measurements straight in your head.

 

 

Thanks alot for the comprehensive tutorial, mate. Really aappreciate it. I did a bit of fiddling around today, and decided to try ur method. If possible, i might try cutting the boss neatly and move it to the lower control arm so than i don't have to make a new pivot point