RX7 FC finding out what it wants to become

Stock spring rate is actually 90 to 95 pounds.

We run cut stock springs on our racecar. Racing beat rear springs are actually SOFTER at about 80#.

If you are not racing, I think anything above 140 on the rear is pretty damn aggressive.

You can get any spring rate you want for racing. Some people will run 400# rear and 850# front. This would be for a PREFECTLY smooth surface to make sure the front end does not roll.

The front suspension on these is not so good for camber gain. (like nothing). Therefore, the traditional method to get them to grip is run fairly stiff front spring rates to keep the front end from moving and then dial in your camber until you get evenish tire wear or tire temps. Obviously, you need to do things with the rear end at that point. This is where you can see crazy high spring rates on the rear.

This doesn't work so good for a street car.

My recomendation would be Racing beat springs all around (or 1 coil cut stock springs on the rear)and a decent set of struts (Bilstein or maybe try the KYB gas-a-just).

Why do you have such a high spring rate on the car? What are you trying to accomplish? I would think that high spring rate is adding to your "blown shock" feeling. The stock replacement type struts for these cars are not meant to deal with that type of springrate.

P.S. The DTSS isnt that noticeable to me. Until you get rid of it. Once eliminated, the car turns MUCH better and the rear end dances a little more allowing the car to rotate predictable and smoothly without being scary.

RX7 spring info in below linky.

http://www.mazdatrix.com/h4586-92.htm

Wow someone got the stock rates very wrong where ever I saw it, got to love the internet. Well here is the story, I got the car with stock rear springs cut from 14" to about 10", the car also has a set of cheap ebay struts. First time driving the car it would bottom out on a rough but normal road. Also the rear end will dance and jump around when it hits bumps. So I found a set of 180lb progressive springs at work and put them on the car. With both springs of the car the new springs feel stiffer but not 100lb stiffer so maybe what was wrote on the new springs was wrong who knows at this point. With the same the new 10" tall springs the car sits about 1-1.5" higher. Also I tested the struts the pass side was fine. The driver side is 100% gone I pulled it out and did it by hand so I know for sure! Its more or less just there to hold the spring up. If that's not causing 90% of my issue I would be very surprised.

So with the new springs it does not bottom out on the same road but the back end will bounce after hitting a big bump where as before it would just slam the bump stop and move around from side to side. So now it feels like it has a blown strut where as before it was just all over the place and very inconsistent. So now I just have to get another set of rear struts (I will try new springs after the new struts are in and I have a better baseline) I am going to get a set of the KYB gas-a-just. Just simply can't beat the price and this is not going to be a track day car, more like a performance DD.

So as of right now I can't say to much till I get the new struts. Hopefully order them soon.

That could be a strut. On these cars I have found blown struts lead to less grip on the end with the blown strut with not much more side effect. However that is with stockish springs....

You will get it. Replace those struts and see where you are.

Good luck!

Yes, for a lens with a max aperture of f3.5, you really need it to be decently sharp from the get-go. Have you tried manually focusing using live-view and using 10x or so magnification? I kind of wonder if good image quality during video work means motion is obscuring the softness.

Could always look for a fast prime for your next lens.

As for your car, I'm with wvumtnbkr; get some good struts and make sure the bushings are all in good shape and see what this thing is like. I do like the suggestion of new springs from Racing Beat all around when you have the money.

I would love to put new springs on the car but one thing at a time so I can see what effects what and then I will have a better idea what helps and what does not. Any info on the TEIN springs?

For the lens, when I shoot video in auto with the camera I shoot with it in TV so I can leave the shutter speed at 50th (I shoot at 25 frames a second so if you double the frame rate you get your best shutter speed to get the right motion blur so the shot doesn't look choppy aka the 180 rule) so I get the right motion blur. That means most of the time it shooting at lets say f8 which would be fine for that lens.

So now where im at, buy shocks or a vintage fast prime...

Ha, priorities, priorities. Sorry I can't provide opinion on the springs.

The TEIN springs are thought of as a beauty or style item more than a performance item. They work, but for a bit more money, get teh Racing Beat springs and have your cake and eat it too.

The rain finely stopped!

Been raining here for about 2 weeks so I have not had a chance to drive the mazda. First clear day I brought it up to work with me. The whole reason was to take it to have the tires balanced at a shop down the road. The car a a vibration from 45-55mph I was hoping it was a tire out of balance or maybe lost a wheel weight. So took it over to the shop and had them do a quick balance. They called back to tell me that I had a bent wheel... Grate. They said it was the front driver and that it could be fixed. So started to think of my options, fix my wheel vs new wheels. Anyway I was going to drive it before I did any of that so I asked one of the guys at the shop to bring his racing corner scales to work the next day.

On the way home and back to work the next day I really had to focus my butt and hands to see where the vibration was coming from. None of the vibration was coming from the steering wheel even though the bent wheel was on the front and it really felt like it was coming from the shifter,trans,drive line. I grabbed the shifter and I could feel it come on at 45 and then go away at 55. It definitely feels like its coming from the drive shaft. So that's something to think about. (more later)

That day we put the mazda on the scales for the first time. I thought about going to the dump or a buddy's farm but I really wanted to see a very true weight and see how I was on all 4 corners. So I asked around and a guy form work had a set of scales from racing circle track back in the day.

So this was another big one for me. I wanted a v8, I wanted it to sound like it did not have a v8 (kinda), I wanted it to looks stock (sleeper), And I wanted it all at around 2700lb. So we dropped it on the scale and checked the number!

So we are looking at 2720 total weight! That's with a bit over 1/4 tank of gas in the car and no driver. I am very happy with that number! From what I have seen through google the stock car came in from 2625-2695lb. So I think that is a good number for dubbing the torque and almost the horsepower of the car. The only thing I don't like is that 55% is up front and only 45% on the rear. But its a FR layout and the motor really needs to sit about 3-4" further back but the oil pan will not allow it. A LS or SBC should have better weight distribution.

So I was soaked on that and I had a 40 min driver on the highway that afternoon. Got on the highway and hit 70mph (the speed limit) and the vibrations came back and this time if felt like the car was going to fall apart! Got off on the next exit and took the mazda home and swapped it out for my DD. So the vibration was a big issue and needed addressing. It hits at 45 then goes away at 55 and if you cruse at 60 its fine. When you let off on the car it starts up again when the drive line become slack. So I am really thinking its the drive shaft.

Next day got the car on jack stands and let the wheels spin under power in 2nd gear and put my hand on the drive shaft to see if I could feel it shake or wobble. Nothing. Called up a local shop and told them the issue, they said it is more then likely the balance. Took it to them and they said there is no way we are letting you run that spacer so lets re-tube the shaft and balance it. So I did, came back and got the shaft and went to install it on the car only after I put a new seal on the back of the trans (old one was leaking). The new shaft was to long... Really sucks I even took pic with measurements to the shop to show them how my set up was working and how much room I had to play with. Someone on there end must have had something mixed up because the new one is more or less a good inch or more to long. there goes the whole weekend. I did call the shop back right before they closed and they said bring it back on Monday. I cant take it back myself so I am sending it with someone with lots of photos and measurements! But the work they did looked really good.

So that's where im at right now, new struts are on the list but this jumped in front of that since its more of a safety thing. Don't want any important bolts to come loose with the vibration, really hope this fixes it! I even went as far to weigh all of the hardware im using to bolt it back in to make sure it all weights the same.

I got the drive shaft back last night ran home and offered it up to the car and it fits! Very glad it fits really well and should work good. Aka should the bolts I have did not fit so iv got to run to the store this afternoon and pick up some new ones. Only bad thing is that its going to be raining by the time I get home... Oh well should have sometime this weekend.

More miles on the mazda today! Let a buddy of mine drive the car, he is only 16 and it was his 2nd 5 speed car that he has driven (other then his DD) He did good and the did well. Its very finicky to drive he had a hard time going smooth and keep from bouncing the car around while shifting through the gears but he said the clutch was nice and easy. Car is still running good and had a chance to do some little things like safety wire for looks and to keep bolts from backing out, as well as adding some rubber on sharp edges to keep things from rubbing. Also had the oven going to powder coat some parts for my dad so I tossed some in for my car at the same time.

Biggest thing is I did a driving video from a while back, its up on youtube.

https://www.youtube.com/embed/K0Fijuc1wio You can hear the vibrations on the 60 pull, you can also hear the through out bearing starting to get mad at me in the last pull. Hope yall enjoy! Getting close to doing a final video of the finished car!

Im still moving on with the car, not as fast now because im driving it more and its cold out and dark. So to start some pic that make the car look good haha.

So here are some pic that I don't think ever made it on here.

Rear struts with the stock chopped springs.

New springs I was going to try, I am using the short dark gray ones. They seem to be doing really well and new struts should come in soon!

Also started making new trim parts or of metal to make the inside look a bit better.

Should come together soon.

Also since my new struts are not here yet I decided to try and figure out the vibrations in the car. Got under the back of the car with a crow bar and started to push and pull to see if there were any loose bushings and no such luck. I did align the rear end with strings. It had a lot of toe in in the rear and I put it back at about .5 degree toe in. Hope that helps. It started with .7 and .4 toe in so that should help.

You still have the vibrations after getting the driveshaft fixed and balanced?

If you push the clutch in at the speeds it vibrates, does it still vibrate?

I did take it for a drive later last night and drove it to work today. With the alignment the vibrations at 45mph have almost gone away, still shakes at 70mph. So more info I figured out on the test drive- Alignment did seem to make the vibrations much better. Did not effect how the car felt in normal driving conditions. There is no vibrations under hard acceleration, did a pull from 45-80mph and it felt smooth and very planted. When I let of the vibrations started abruptly and very hard. The vibrations get worse when I let off the throttle after any acceleration. I think it might have to do with the struts. With load on the back it seems fine but when the back end gets light it gets worse?!? Really waiting on the struts to move further with the car. Seems almost silly to try and fix it when I know the struts are blown.

As for now the driveability from 0-60 is really good much better then when I started. The car will run at 70mph but its to much vibrations to drive more then a min or two.

In reply to Skervey:

What happens when you push in the clutch?

Also, what type of bolts did you use to put the driveshaft on? They should be shoulder bolts that barely fit through the flange.

Have not tried the clutch yet I will give it a try. I used grade 8 bolts since the original bolts don't fit the new flange. I did have to grind the heads to make then fit but I put them on a scale and weighed them down to the .00 gram so they are all the same. Then weighted the lock washers and nuts to make sure everything was 100% equal.

New struts come in next Monday if USPS keeps to the word so im expecting them here next Wednesday fingers crossed!

Also I have developed a exhaust leak it sounds like its between the header and the block. It just started last night so I will have to find and fix that to. Sounds like a old truck now when I floor it... Makes me sad!

It is important that the driveshaft bolt SHAFTS fit tightly through both of the flanges. These SHOULD be shoulder bolts. If they do not fit tightly through both flanges, the driveshaft can wiggle a bit or be slightly offcenter and cause your issue.

Push the clutch in when the vibration is happening and see if it immediately goes away. If it does, it is not the rearend or driveshaft.

Not the rear end or driveshaft? I would think if it quit with the clutch pushed in that would lead me to the drive line?

I am using standard bolts for the drive shaft. Didn't know any better, the bolts I took out as well as the bolts that I was given with the new drive shaft were standard bolts. Might have to see if granny speed has bolts or get under the car and start doing some measuring. That would be a cheap thing to try and that makes since anyway.

I was not able to really try that this morning it was VERY foggy on my way in. Did not get much over 45mph. I should be able to try again tonight. I did check the headers last night and all of the bolts had gotten a bit loose. I guess it is from heating and cooling so much but I was thinking that after I got them nice and tight it would fix the leak but no luck. Still leaking so now I will check the flange see if that's loose. Might have messed up the gasket when the bolts got loose. One thing at a time I guess!

Clutch in will isolate the engine and half the clutch from the drivetrain.

The rear wheels still spin the rearend and driveshaft at road speed.

Try the clutch in and see if it goes away. Next will be trans in neutral with clutch in and trans in neutral with clutch out.

If the vibration changes with any of these tests it will point us in the correct direction.

Sounds good! I am also going to try and move the tires around see if I have a bad tire or something like that.

Any steering wheel vibration? A front wheel bearing can do this. Check to see if the front wheels have play.

Any squishy brake pedal or long initial travel? That can indicate wheel bearing or a rotor issue causing vibration due to pad kickback.

No vibrations in the steering wheel it feels like most of it is in the body and the shiftier. The brake pedal does have a fair amount of travel but with nothing to compare it to its hard to say. The the brakes work very well and no clunks or vibrations while braking. Rotors were said to be new when I got the car and they look new so I don't think there to fault but not counting them out. I have yanked on all the wheels and they are all solid no movement nothing loose.

Got to test it a bit yesterday afternoon, seems that the vibrations at 70mph are not consistent. I got it to do it once but that was it. Did put in the clutch and it helped but it did not go away that second, it went away when the car started slowing down. Also when going slower I felt what I can only describe as wheel hop. Feels like one of the rear wheels is jumping up and down. Did not move the tires around had to help a buddy install a bumper and winch last night, he is coming over tonight to wire it up.

I won't have another chance to drive the car till Monday and the shocks are coming this Friday so I will try and get them on the car Sunday night then cross my fingers. If nothing else I am really looking forward to see how much better the car feels in corners! Love the feeling of this car just need to get the vibrations and a few other things and it will be very close to a sorted car! Getting excited!

More photos!

New struts are in the car and it handles!!! Very happy with the feel of the car not that they are on. They are more of a street set up so I think it should be nice for me. The car is a bit bumpy but feels tighter now.

Also got lucky and it stayed foggy till later in the afternoon so I gas some pic of rx7 as well as my motorcycle and the other toys!

All of them needed to be edited but I have been looking forward to shooting pic with the winter fog.

Well I had my dad and brother drive the car and I could feel just how loose the drive line is. I am used to driving the car and I baby it most of the time so im used to how it feels. So the car went up in the air and I started feeling for the issue. Turned out the diff lets about a 1/8-1/16 of a turn before it catches. That's not going to work but thankfully I have a spare LSD rear end sitting in the pile of spares. I was going to wait to swap it but with the forecast is rain everyday for the next week so I will just start tonight.

This must be a part of that lat 5% I was warned about haha

-Game plan

-Pull rear end

-install poly rear bushings

-swap LSD diffs

-find fix exhaust leak

*extras

-Install S/S brake lines

-Front arm poly bushings

-Shorten spindles