Handling Characteristics
 

So, I recently put an LS1 in my FD. Really, the only thing that consistently bugs me is that the balance of the car is a little different. So, i'm wondering if anyone has confronted this and started adjusting the suspension to more suit the V8 application.
Just wondering what people have had luck with, especially people that may be tracking their car.

I wouldn't think this would have been much of a problem since the LS1 is lighter than the 13B?

I could be wrong, but don't think it is lighter. Most of the LS1 weight quotes I read online varied from 380-430lbs. The interesting thing is that I thought the rotary was a little lighter than it is, which makes me wonder if part of what i'm feeling is the different power steering pump affecting the steering feel, giving it a lighter steering feel.

All else equal, an LS-engined RX-7 is going to be about 50 lb. heavier vs. stock 13btt, and pretty much all the additional weight is going to be on the front wheels. At least that was the case with mine (2780 lb. bone stock base model, now ~2830 lb.)

That said, any change in handling feel could be more due to changes in steering geometry or changes in power steering. IMO...

This is what i'm starting to think, although that little extra weight must do something as well. Which is why i'm interested to see if people have made adjustments in what they bought or tuning what they already had.

What was done on your car to adapt the LS PS pump to the FD PS rack, from what I remember, the LS PS pump runs at a lot higher pressure than the FD pump and to use the LS PS pump with the FD rack optimally, the pressure needs to be reduced. Someone makes a adjustable regulator so the correct pressure/feel? can be dialed in.

Re the weight distribution, from most of the threads where it's been measured, it doesn't change much from stock, the T56 moves some weight back in the chassis.

Theoretically the CG might be a little higher due to the LS having weight higher up, but I'd first look at the PS setup.

I'm not sure. I can't find my receipt which has all the components installed. I will definitely take a look at it though. Thanks for the heads up. At least I was heading in the right direction with my thinking.

Found my receipt. There is something on there labelled "adjustable power steering valve". So when it gets a little warmer i'll go out there and poke around to see if I can find it. Thanks again.

LS swap, too much PS assist
 

Here is an old thread on Norotors about this issue:

http://www.norotors.com/index.php?topic=5208.0

norotors.com is a good place for this one.

If you have the Hinson kit you may be experiencing some bumpsteer issues. With that or the Samberg kit you should have an alignment done or at least checked.

I assume you have replaced all your bushings and rear pillowball bushings if they are original? 20 year old bushings are toast.

My LSx FD won the skidpad contest back in the day for the Sport Compact Car USSC event. If set up properly... they kick ass on the track. 49% weight up front/51% rear full tank of gas 2800lbs without driver.

FD LS bumpsteer
 

Oh yeah I forgot about that, the deal is with the V8 conversion the steering rack get repositioned vertically which means you have to use tie rod ends that compensate for the offset. Some companies have an adapter on the ends of the rack that offsets the arms, but it's not a great setup IMHO. Do a quick check to see if you have anything on the ends of the rack that offset the arms and then look to see if the tie rod ends look "tall" vertically, like they are longer than a normal tie rod end. If not then you will probably have bumpsteer problems which means that as the chassis moves vertically the front wheels change toe. You can get an alignment as GNX recommends, but that will not eliminate the problem (if you have an offset rack and stock tie rod ends), it will just make a little less noticeable.

If you take a couple pictures of your tie rod ends and post them (assuming you have no adjusters on the ends of the rack), it will be easy to see if you have tie rod ends that are the correct ones.

If you want to read up on bump steer you can probably find something on line, the best book I know of that explains in depth what it is, how to measure it on your car and how to compensate for it is "Prepare to Win" by Carroll Smith.

I have the Hinson kit. This is all new territory for me. I've honestly never dived into this part of my car. It's always just been so perfect that I never had to learn about it. I know they did new left and right rack boots and a tie rod end. I haven't got an alignment yet, but I will very soon. It's been on my mind since the swap.
I could have some bump steer, but I don't think that's the real issue. I have a little bit of experience with bump steer as my Mustang wrote the book on it. LOL.
I'll take a look at the ends, but looking at my receipt, I don't see any extra parts to the effect of adapters and such. Where would I purchase such adapters?

Check with Hinson, and also with Samberg, links on norotors.com

Buy a flow restrictor from turn one for your powersteering pump. Alot of the ls1 v8 guys do this to bring the GPM of the ps pump closer to the original, if not lower than the original PS pumps GPM. This will improve your "feel" and reduce some of the twitching.

You'll also need a 22mm thin walled deep socket to remove the old one.

Turn One - AN-6 Flow Restrictors

+1

I rock the turn-one restricter and you definitely get more feel over the rotary setup.

I have done a ton of research in this...

First, what is the car doing exactly?
Why does it feel different? How?

Is your steering rack spaced as high as possible, just barely clearing the oil pan?
Which oil pan are you running?

I dont know much about Hinson, but Samberg allows you to run an F body pan which is 1 3/8" thick at the front, and that gives you the most space to raise the rack.

If you dont do this, you have to run more spacers on the spindles and the more you run, the easier they snap....

I decided on the full Turn 1 power steering pump with lightweight pulley.

Man, did that make a difference or WHAT! Crazy. Never drivn the flow restrictor setup though.

I had bumpsteer issues maybe similar to what you have, but then replaced my rack spacers and tie rod ends with samberg equipment. Fixed my issues at least.

^ Thats exactly what I run after my stocker died at an Auto X event. I have never looked back. The LS swap will acutally move weight back and up a little. The trans is where most of the extra wight comes from. 75lb vs 125lb. The engine having more material up top raises the CG. Overall front axle weight stayed about the same on my car. Overall weight was up a little. About 40lb. As for bumpsteer, I run the samberg outer kit. Works just fine.

Does anybody think its crazy to not run ps on a road race car? That's what I was contemplating when I build mine.

i put a manual rack out of an fc when i did my swap. wheel is not heavy at all besides moving to lock when the car isnt moving due to the variable ratio i believe mazda calls it. wanted to save weight since mine is not a DD.

I just picked up a swapped FD Tuesday w/o PS so I'm seeing how I like it, but honestly PS is nice to have for a DD, so it's sort of on the "to do" list for that car, but probably down the list a ways.

There is PS in my '91 Miata and I think the feel is fine on that car, the turn in is really good even though some people would argue that PS should not be needed on a 2200 lb car.

I'm running a 315/30/18 front and no p/s hooked up. Aside from parking lot slo speeds its fine.
I think the feedback is better not running p/s.

Sorry to be just getting back to this now. I don't get on here as much as I would like. I think I am going with the Turn 1 pump and the Samberg bump steer kit. Did you get the lightweight pulley from Turn 1?
Thanks for the input. I'm excited.

Aside from weight, power steering cant hurt you when road racing. It actually really benefits to have power steering because you are constantly in full control of the steering rather than fighting it. I road race from time to time but talk to a lot of actual drivers and they unanimously prefer power steering in their race cars. To each their own tho. You can always try different lb springs and revalve the suspension to compensate for the 50lbs or even have the car corner balanced.