ATC529R

A quick background.

1980 SA 7 with v8 (i know, I know....)
now that the driveline seems to be getting fine tuned I am looking at the driveability and get some of the quirks worked out.

My goal is to get it to be a daily driver sleeper with the power of the v8 and handling that isn't going to get me killed.

My compaints on it now

1 front end-shock are shot and it's clanky to a certain degree
2 getting on it coming out of corners can be scary AF
(I've read thats a big issue on these cars and will probably remove the stock sway bar when I dig into this)
3 very small complaint, but rear bottoms out on some bumps at speed-----but if going high speed on a sweeping corner this could be disaster, so it's an issue in the mix

Etc. the rear of the car seems "ok", but I think the 245 rear tires combined with the 205 front tires probably adds to the sketchy aspect coming out of a corner on the gas a bit.

The stance on the car right now is perfect looking though :-)


Current set up:

ALL bushing, inserts etc on front/rear suspension, control arms etc are new, poly.
All the steering arms, knuckles etc, balljoints etc are new...basically if it connects, has bushings etc it has been changed.

REAR
Racing beat rear springs (112lb)- Rubber inserts in the spring to stiffen it up a bit
KYB shocks
stock sway bar
245/50/16 tires

FRONT
Racing beat springs (145 lb) (cut a bit on the bottom side, maybe 1/2 inch)
Racing beat sway bar
205/45/16
KYB shocks
Slip on coil over.......BUT....I did not weld it, I simply rested it on the factory shock perch and do have thick rubber in there between the two
The coil over is at the very bottom of it's adjustment and not really doing much


HERE ARE MY DEFINITE PLANS:

Rear shocks from fox body mustang - Koni Oranges
Front Strut inserts from rear of MRII - part number 1072
Remove factory shock perch and weld on the lower shock perches from T3
Make sure all inserts, bumpstops, bushings etc are in good shape
Will probably change to rubber bushings up fron on sway bar

Most Likely pick of options:

Lower control arms from T3
https://technotoytuning.com/mazda/fb...-sa-and-fb-rx7
This should help me increase the front track a bit, give a little negative camber and maybe a little less twitchy. I will switch to 225 R comp's in the rear down the road once I burn off these 245's

The shocks are roughly 500-550 total, and the lower control arms are like 450. call it a grand


Secondary options
Racing beat adjustable lower control arms.
(this would be a tough sell though as they're expensive and look to be based on factory ones)---the T3's are much cooler with more options for sway bar mounting as well

switch to smaller diameter springs up front which would also call for different upper perches and use t3 adjustable camber plate

going that route, it's still 500-550 for shocks, then 325 for camber plates, 100ish for upper perches and probably 150 for springs -----that's 1075 to 1,125$

BUT----going this route would not widen my front track any, which is the main reason I am probably going the lower control arm route.

Sorry for so much info, and I know where the search button is. heck, almost too much info out there. Just figured I'd put this out there with my setup and plans and hopefully get more input before I do anything, as I want this to be the last time I do the suspension for a while.

yeah, and those KYB's are garbage out of the box up front IMO...or at least on my car. heck, I think the blow sitting in the garage!!!

Maxwedge

iTrader: (1)

That's what T3 says... But it's actually difficult to mount sway bar end-links to their arms unless you have quite a bit of lowering in the front. The mounting holes in their arms are not angled inward like on the stock arms and poke the links outward instead of inward, making it near impossible to connect to the bar.

I ended up getting some 1-off links made for me so I could use the swaybar. I would definitely Not operate the car without a front bar.

ATC529R

thanks for the heads up on those T3's. That kind of money and then spending more to modify it is crazy. and those RB one's price is insane.

I saw where one guy made his own and the T3's look to have heim joints as well. curious how that would feel on a DD.....

I am thinking of just cutting the stock ones and adding 10mm ti 1/2 inch or so to make the front and rear track the same. It wouldn't be that difficult.

I just don't have the experience of driving other 7's with different setups to know if it would help the car.

j9fd3s

iTrader: (3)

some of the Fords have sway bar links that look promising, this one is from a 2007 Crown Vic. Ford stuff is expensive though, $60 each!

mhr650

If you want wider track on the front, just drill new holes in the crossmember. I put my crossmember in a mill and moved the holes out a half inch each side, once I drilled the new holes I welded hardened washers on both sides for good measure.

I needed the extra track width since I couldn’t get enough camber even with the camber plates adjusted all the way in, to the point the 2.5-inch springs were almost rubbing on the strut towers.

ATC529R

Thats a great idea man!!!!

mustanghammer

iTrader: (3)

On the rear, I would do KYB AGX shocks instead of the Koni Orange shock. Nothing against the Koni Oranges but they aren't adjustable and the AGX shocks are. I have a pair of them on the back of a Fox Mustang and the work well and are easy to adjust. Being able to control rear shock rebound is important because it gives you a way to tune weight transfer under braking.

I made my own adjustable lower control arms: https://www.rx7club.com/build-thread.../#post11662697
Not the prettiest welds I ever did but they are holding up well in a racing environment. On the street, arms like mine or the ones from T3 are going to add some harshness because of the heim. Arms like this do provide another way to get camber so my alignment guy likes them.

Modifying the cross member is also an option. Concerns would be how straight your car is and are you able to get the cross member centered in the car now. If your car was ever in an accident this could be an issue. And in general, cars are not always perfectly square. My race car has been hit up front in the past, but with camber plates and adjustable lower arms it is not an issue.

t_g_farrell

iTrader: (1)

Whats your rearend setup since you have a v8 (oooh I hate even typing it)? If you are still stock on the rear end, you do not want poly bushings in the 4 axle links or you will get early binding as it moves up and down. Your current suspension setup is dangerous to say the least. I would judge the handling you see today with what you will get once its correct. The shocks choices are spot on. Not sure about the front spring ideas you are posing. I would keep using the RB springs with stock components and the new shocks and get it all aligned with the rear bar removed and see how it all feels. Your changing so many things at once it will; be hard to know what works and what doesn't.

ATC529R

Thx for the heads up on those KYB AGX Hammer...... I'll look into them or at least adjustable shocks. I am really dissapointed in base KYB's. I think I'll go with drill the crossmember to move the lower control arms out a bit though.....as the front end is already really harsh.

Toying with the idea of getting stronger springs all around than the RB ones, as the rear is too soft and the front is as well, but the front is like riding around on the springs. the last kyb's I took out were shot and they were barely used during the build...so they wore out just sitting there. I already had the new KYB's before I knew how bad the old ones were and slapped it back together.

@ Farrell.... I think they are rubber bushings in the rear suspension, but it's been a while since I did it and it's all been undercoated. I'll need to get up under there once it's on the jack stands. I am glad you reminded me to not do it all at once. great advice. I tend to order a bunch of parts and not get around to putting them on for a while. Pull the rear sway and replace shocks then decide about rear springs. I think the front RB springs have to go though.They look to be mostly compressed just sitting there, and me cutting a little off the bottom of them to make up for not welding the coil over sleeve lower was a dumb move. either way, I need a higher spring rate and more (any lol) dampening.

I look at the stock strut mount tops and they are obviously an inch or more higher than if I went with a camber plate bolted underneath. I like the ide of having more strut travel. am I flawed in this thinking?

j9fd3s

iTrader: (3)

if ride quality is a thing, you should replace the bumpstops, the Mazda used rubber which turns to stone. modern cars use a urethane, its very easy to find bumpstops for the front, basically any strut car has something that works

the rear is harder because Mazda used a weird thing that bolts on. also for the lowered cars Mazda has you shorten the bumpstops, http://foxed.ca/rx7manual/manuals/comp.manual.pdf

yeti

iTrader: (1)

@j9fd3s Say no more! I have the perfect bumpstop replacement for the rear! 2005-2013 Toyota Tacoma rear bumpstops fit perfectly. I personally bought rev244-0000 as they were the cheapest bump stops I could find at the time. I seem to recall the dimensions being perfectly the same but they could be very slightly different. Either way, bolt in replacement.

mustanghammer

iTrader: (3)

Which V8 did you use?

Given that your car has a different and potentially heavier engine, some spring recommendations you get here or in the rotary world may be a little off. It is likely that front spring rates may end up being higher than what would be installed in a rotary powered FB for the same intended use. This can also affect the rear spring rate you need to use because it is all about balance.

What I have seen over the years is that increasing front spring rate (sometimes to an extreme) doesn't generally affect ride quality as long as the springs are paired with a quality strut. Ride harshness becomes more of an issue when rear spring rates are increased and aren't managed with a good shock absorber.

ATC529R

Thanks for that bump stop info. It still has 40 year old ones on there now. I'll definitely add those to my list. @ hammer, it's a chevy 350, not LS but pretty built. So there is more weight up there.

Not hating on RB, but even the rear feels like it could use heavier spring rates to a slight degree, but it only hits the bump stops sometimes. I'll probably do the shocks 1st and get rid of those POS base KYB's

from RB "These springs have been designed with a rate increase of approximately 20% (front - 145 lb/in) and 20% (rear - 112 lb/in) with a modest drop of 1-inch (front and rear)."

those front RB springs have to go. I'm thinking double the front spring rate based on how the current springs ride. That being said, once I weld the lower portion of the do it yourself coil over lower down the strut, it should allow for longer springs. That part I'm going to have to wait to get the off the car and the strut fabbed up.

mustanghammer

iTrader: (3)

Coil overs are the answer. I ran 2.5" coil overs on OE sized strut tubes with no issues. I believe I was running 7" tall springs at the time. I like coil overs because the rates are more consistent and there are allot more choices. But even then, some are better than others. Swift and QA1 make springs that have allot of travel because of the way the coils are spaced. Eibachs are also pretty good. The other thing is that coil overs provide more tire clearance

I also converted the rear of my car to use coil over springs and put adjusters on the axle housing so I can set ride heights to what I want. Also to balance the car.

ATC529R

I read through your build thread this morning. NICE WORK BRO!

I noticed how you moved your strut towers up an inch front and rear. Great work, and also let's me know I'm not crazy in my thinking more travel is needed. Granted, yours is lowered a lot more than mine and I notice you added an inch on the bottom of your front struts and have major adjustment options on the rear. Net-net, you are probably getting similar travel as stock, but with the advantage of having the car ride lower. I don't know that I want to pull the rear end though. I am assuming you had to weld on the coil over sleeve to the rear axle- is that right?

I guess that could be done w/o pulling the rear end, but it would be difficult, and probably dangerous welding that close to the fuel tank short of welding the sleeve with less than full weld around them. Do you remember where you sourced those?

I have a busy couple of weeks, but looking at your thread and all the info here makes me want to get out there after hours and get this thing started. Maybe I'll even do half way decent pictures this time. I suck at build thread and pictures.

j9fd3s

iTrader: (3)

have you weighed the car?

ATC529R

no, short of going to the scrap yard and pulling it up on the scale where would I be able to get it weighed on all four corners? not a specific place, but I don't think most shops would have that. mostly for racing I would guess. It should be about stock SA, base model. short maybe adding a couple hundred pound for the v-8 and some support structures.

ATC529R

This is where I am starting from. I'll get to tearing it apart and forget the before pics. lol

current stance I think is good:






The front, as you can see is loaded up just sitting there. ---yeah I F-ed it up. Rear with rubber insert. wondering if the insert increases the spring rate.

Maxwedge

iTrader: (1)

For my own clarification, what exactly did you mean by "getting on it coming out of corners can be scary AF. I've read thats a big issue on these cars and will probably remove the stock sway bar when I dig into this)"

The cars are not known for being scary AF. They're known for being the best handling bang for the buck 1979 had to offer. I think what you're referring to is the "snap oversteer" phenomenon that can happen when the rear compresses to it's limit on one side and binds up (a minor flaw in the rear geometry). I drove the ***** off my first (still new-ish) '85 RX7 and never experienced this, and that car was fun and easy to steer with my right foot. Your problems stem from adding an extra 200+ lb's over and in front of the front wheels, on an old softly-sprung little car. I am not against engine swapping these cars, but you definitely need to spring & damp the car for the new weight balance (as Mustanghammer is helping you with).

You went from a 51/49 weight balance to what... 58/42? You made a burnout machine that can't handle any more. RB springs make a difference on a stock car but can't handle that extra weight and weight-shift you introduced. I bought my current car to build a SBC conversion and I got my spring advice from T3 and Ground Control. I was going to get my coilovers from one of them so had lots of emails with them. Also talked to Granny's a lot because he built my rear end. They all suggested 400 front and 200 rear springs for a SBC FB street build. I ended up using a built 13B and I have 300/200 springs now that ride nice.

"3 very small complaint, but rear bottoms out on some bumps at speed-----but if going high speed on a sweeping corner this could be disaster, so it's an issue in the mix" I have my rear lowered 1" with a larger ford 8.8 rear and I never bottom out. Get rid of that weak old suspension. *I did cut 1" off the stock bump stops.

"Etc. the rear of the car seems "ok", but I think the 245 rear tires combined with the 205 front tires probably adds to the sketchy aspect coming out of a corner on the gas a bit." I'd keep the 245's if they clear the fenders. You need as much grip on the rear as possible (since you shifted the balance forward, away from the grippy end). I'm rolling 195 front / 225 rear and want something wider on the back. You shifted traction OFF the rear end by engine swapping so you need to adjust your suspension to shift it back now. For more grip. So why put skinnier tires on it? I went to a few burn-out contests in one of my trucks and I always put skinny spares on the back when I got there so the truck could just spin-spin-spin those little tires. Don't do this for street driving. Hell, can you fit 295's?

The racers on here can give you the best spring advice but also look at the V8 section. Lots of guys there have fought your demons already.

Maxwedge

iTrader: (1)

Just saw your picture post #18. Nice stance: the car does look good.

MustangHammer - When I went to front coilovers I got clearance issues with the adjuster ring vs the tire. ATC's 2nd pic shows how the stock (or RB) springs have that upside-down beehive shape and the lower end is shaped around the tire. When I installed my T3 coilovers I found the adjusting ring (bottom of spring) rubbed HARD on the tires that fit fine on the old suspension. This has been a real PITA because my low-mile wheel sets don't work anymore without 10mm spacers on the front. So now I'm buying more wheels (because I hate spacers). Is this a known C/O thing that I didn't know?

j9fd3s

iTrader: (3)

we have a scale at the dump, which is i guess pretty nice. i'm just thinking if the car is 2400lbs the RB springs are probably ok, but if its like 2700lbs, maybe you do want something stiffer.
the FB is pretty nice even the race cars don't end up with very stiff springs, so you can kind of have your cake and eat it too
For example, you're running 145/112 springs in your street car and the race car setup is 350/150 or 175. its not like the honda where we were at like 750/1100 springs

if you gave me your car i'd probably do 250 springs in 2.5", with camber plates and bumptops that aren't solid. the rear springs are fine, imo

ATC529R

@ j9.... I should mention there is always someone else in the car with me, and I am pushing two-fitty. So say me and passenger are 400 added to a 2500lb car. I assume most racers set um up with no passenger lol. 2900 or so is my estimate, but I can swing by the recycling yard next time I take her out.

@ max... I do have spacers on mine and the front and rear fenders are rolled

ATC529R

Thank you for your help.

Maxwedge

iTrader: (1)

No problem. I don't have the experience of the other guys here but I went through this research when I built my car. I just don't believe the stock or slightly firmer RB springs will handle the weight or weight transfer of the bigger engine (50% more weight / weight shifted foreward off the rear tires / 300% more torque when you tap the throttle out of a turn).

j9fd3s

iTrader: (3)

2900 is probably close enough, although if you can put it on the scale maybe we get surprised

we usually set the race car up with the driver, because that it how the car is loaded when its used, for a street car its kind of optional. basically you want the ride height level WITH the people in the car