Just went to pick up my car from KDR who was tuning it with my stage 4 BNR turbo. Car is an 84 GSL-SE with a FC turbo engine etc... First, I was a little disapointed with the power as the turbo I ordered was supposed to have a 14lb spring, but it was not holding over 6 psi without using my boost controller. Anyway, it was tuned to 15 psi at 270 horses and 230lb of torque. It gets to full power at 4k rpm and holds it all the way to 8--nice and flat. Car idles excellent and I am very happy with the tuning.

So, I up my girlfriend in the car to show her how it pulls. Drive a couple miles--great. I stop to do a launch--mistake. I rev to 4k and drop the clutch. I'm greeted with a some violent hops followed by a weird rubbing noise. I pull over and I'm dismaied to find my rear left wheel rubbing on the fender--pushed all the way forward.

I get the car up on my trailer and crawl underneath it. The entire driveline looks good, but the rear right control arm is bent up in a perfect arch till it rests on the chasis. I will post pictures as soon as I find the cable to my camera.

So, what are my options for my power level?

I found this one on the Respeed site, but I do not know if that will handle what I need and if there are better options.

http://mrcmfg.com/catalog/product_in...products_id=67

Any personal experience and comments appreciated (besides the obvious "do not do anymore hard launches").

Thanks!

 

ask billy, he'd know

 

I can say from having a 300rwhp first gen that you never want to hard launch it with the stock suspension. Honestly, about the best thing that you could do is a back half and a Ford 8.8 rear end. Then you have to worry about chassis flex and cracking windshields. I'm sure Billy would give you the best advice. Just my 2 cents.

 

I dropped the pressure on my tires at a well prepared track, did a clutch popping launch and "broke" the left lower control arm in half. Turns out the bushings were seized so I think that may have played a part. Used a 3/8 extension inside the rod as a connector, a pair of vice grips and a bunch of trusty duct tape from the standard emergency rx7 repair essentials and gently drove the poor girl home with her broken wing.

 

i didn't break the arm, but i did break the bracket on mine, and mine is stock

 

"Doctor, it hurts when I go like this..."

 

then don't go like that

 

Well, my suspention is not stock, but it looks like the control arms were. Billy from Respeed would not quote the power numbers that the control arms are good for, but said that they are "beefier" than stock.

Yes, I know, no more hard launches. The car is actually a road racing car. How ever, I just picked her up after sitting a while and I wanted to see what she can do and show my girlfriend...

Note to self: no hard launches. However, it is nice to know that you can if needed. Anw as with any car, you do upgrades and get more power and then just start changing out the weakest links as they start to break and show themselves.

Speaking of which, it looks like my Turbo II tranmission is shot. Any one know a good Japanese engine recycler on the East Coast where I can get a good, low miliage one?

 

There are lots of guys still using the stock control arms with big power numbers, so swapping to the RE-Speed parts should do the job. Make sure to add polyurethane bushings everywhere else to improve the ride and response.

 

Most of the bushings are pretty new and the rear suspention is a custom setup by a guy that is known for building them. I forgot the name, but I can grab the paperwork when I get home. Most of the bushings have been replaced by joints (which is actually quite loud) so there are not many busishings to even look at.

One of my worries is that perhaps something is not aligned right (rear suspention, custom driveshaft, transmission mounts, etc) that puts undue stress on the rear end causing it to break like it did. The rear suspention setup was done before I bought the car. However the car was an autocrosser and was pushing 12hp. Such misalignment would not be obvious at that power level. Now, close to 300, miss alignments start breaking things. Maybe the turbo transmission mounts or the custom driveshaft have issues? Any suggestions as to what I should check? It may be fine and just need to be beefed up.

 

I would like to know all the modifications and bushing material used throughout this "custom" suspension you have. You may have an issue that is not going to be rectified with the rear arms you have purchased.

-billy

 

I found the manual, it is the G-Force Tri-Link suspention by G-Force Engineering. I did not install this suspention, so I'm not sure exactly what pieces are aftermarket. I will dig into the 46 page manual though to see if there are any alignment issues or adjustments. It looks like those control arms are stock, but I could be wrong as I have never seen underneath a totally stock car. They are not the same gloss as the G-Force parts though.

 

The tri-link is a third link. (top middle of the pumpkin)

Please look under the car and check two things:

a) WATTS removed and pan-hard added.
b) Stock short upper arms removed. (If they are not removed check what bushing material is in the ends)

Let us know what you find out.

-billy

 

Will do. When I get home tonight I will crawl under there with a camera so you will see what I see. I know that is a third link, but it is also the name of their suspention setup. For example, it uses Koni shocks. It is a huge book, and I will attempt to determine all that the setup entails

 

That car is my old Nemesis, but I can't recall the details on the rear suspension (springs/shocks). I do recall the Trilink and Panhard, and I know it has very stiff springs on it.

Those upper links are probably still on the car, as they were required by SCCA rules until recently. They should have the soft foam rubber bushings in them. I would go ahead and remove them now, since they serve no purpose at this point.

I'm a little surprised you bent the link before breaking a mount. But with that kind of power, and a bad hop, I'm not very surprised that something did let loose. But like you said, its all about finding the weakest link, eh?

Anyway, good luck. I'm sure Billy will take great care of your needs...

.

 

Yup, I was reading the manual and I saw that it was suppoed to have "foam cushion" bushings on those control arms. I can't wait to get home tonight and take a better look. It was raining all day Sunday and I did this on Saturday evening.

From the manual, the control arms are not used (see attachment). Maybe that means that they are not used under cornering but pressure is put on them on a hard launch (?). Anyway, I think you may be right, I may have broken a mount which caused the rear differential to shift and then bend the link. I guess I will give myself a crash-course in this and FB suspensions in general.

 

That which does not kill us, just makes us smarter, and usually poorer...

 

No, the upper arms are useless once the Trilink is installed. They literally serve no purpose. However, if they had stock bushings rather than the foam that comes with the kit, I imagine it could cause some interesting issues.

The only reason they even supplied that foam bushing is because the SCCA used to prohibit the removal of the stock upper links. So, they had to be kept in place even though they served no function, and at the same time ensure that they did not cause any binding. Hence, the "Sloppy" foam bushings...

 

So, I was able to crawl under the car, take pictures, and remove the control arms. First I wanted to say that there are NO upper control arms installed at all. The lower driver's control arm was bent so far up that it was pinching the break line against the chasis.

Everything else looked good. It looks like the tri link merely flexed. After removing the bent control arm, I jacked up the car, gave the wheel a tug, and everything went back into place.

My brand new tire with about 20 miles on it was nicely shaved by my fender, and my fender suffered a little damage but nothing that can't be rolled over.

In all, I could find nothing else broken or bent. So, I guess the remedy is:
a.) Replace the control arm
b.) Do not do hard launches or release the clutch above 4k rpm

On a side note: Good job Toyos for hooking up so well!

 

Some more pictures of both the right and left control arm. Who would think that a little Mazda could bend that kind of steel ?

 

You might want to do yourself a favor while you're under there, and double check where the panhard connects to the frame rails. They have a reputation for breaking if placed under stress.

Good luck with the repairs.

 

Looking at it yesterday, I did not see any stress fractures. I will check it out a little closer when I instal the new control arms.

 

mikeric: You violated Jim Susko's trust and his copyright when you published a picture out of his suspension manual.

 

wow.. goodluck with the repairs

 

Copyright covers portraying someones intellectual property as your own, not displaying it on a public forum. A nondisclosure agreement would prevent the information from being shared, but I seriously doubt Jim has his customers signing those before they buy. Mikeric showing us that is no different then showing the guys he races with the same manual. It's a readily available product that anyone can buy. Mikeric bought that car with it already on there. He did not develop a relationship or personal "trust" with Jim. On top of that, it's a race suspension. While Jim's efforts are valued, he's not the only person to ever use or build a tri-link. I'm sure there's more than a handful of guys on this forum that could draw that same diagram with their eye's closed. To summarize, RELAX!!