23 replies to this topic

[juliancates]

I have a '91 1.6 car and DO NOT have '99 hats nor the FCM kit.

I see that there are two different versions of Jim Daniels' setup guide out there. The first version calls for a ride height of 5 1/4" at the pinch welds. The seconds version explicitly calls out '99 shock hats, and calls for a 4 5/8 ride height.

Can someone please explain to me the difference in the two types of shock hats and why the recommendation would be nearly 3/4" different between the two?

If I run at 4 5/8" with my current setup, would that be... bad?

I ask because the car is fairly new to me, and it's set up pretty low. Depending on where I measure on the pinch weld, it's somewhere between 4 3/8" and 4 5/8". I just took some quick measurements in the garage. That's on the driver's side (it was easiest to get to...) and WITHOUT my weight in the car.

I also noticed that I got some tire rub when I ran wheels with the 25mm offset. When I bought the car it had Kosei K1's (38 mm offset) and no spacers. I don't get any rubbing when I run those... but it seems like I'm giving up a lot of track width. So, I'm thinking the car is just too low.

With all that said, should I just raise the ride height to 5 1/4" ? (And then corner balance appropriately.) If I upgraded to the FCM kit with the '99 hats, should I be able to run at 4 5/8" with 25mm offset wheels? (And would you expect, with the current shock hats, to get rub at that ride height?)

Thanks a bunch for any help and advice here. It's much appreciated!

Cheers,

Julian

[Jim Drago]

You should run 99 hats and Fat cats as that is the best setup IMO. Those numbers are easier ways to get to 3/4 in of shock to bump stop clearance. Use the 4 5/8 number, but you must have your weight in the car.

Jim

[Ron Alan]

Forget the pinch welds(reference only). The key is the distance between the top of the shock body and the bottom of the bumpstop under load. Our set up guy reaches up and uses his finger in between the 2 to gauge distance. My guess is around 3/4". He does this when the car is up on his scale pads off the floor about 8-10". The 99 hats and FC , for lack of a better description, allow the top of the springs and shock mount to be higher in relation to the ground...in essence lowering the car without changing shock travel. How soon you want to be on the bumpstops is your adjustment(travel). The 41/2" dimension you mentioned is pretty accurate with the FC. The FC have a little more forgiveness when you get to them than the older style rubber bumps. But at this height with 25mm offset wheels you will definitely need to roll your fenders and if you have already then the car is probably way to low(on the stops practically)with the shocks not doing much. This is my understanding of coarse..please someone correct me if i'm way off base as I don't claim to be an expert!

edit...ha! what Jim said above in way less time!

[Keith Novak]

To add to what's been said (sits lower, more complaint bump stops, and weight the car), since the FC kit allows your car to ride lower, it also allows for more neg. camber which provides more clearance to the fenders. If they still rub, roll the fenders some more. I seem to remember that with 25mm offset and no fat cats I got a bit of rub at 2.5* camber at the JD setup height numbers. Grabbed a soft face hammer at the track and fixed that in about 10 minutes.

[davew]

Would you make chacolate chip cookies using a cherry pie receipe? That is basicly what you are trying to do.

I have seen this same situation in all forms of racing, from Trans-Am to Indy car. The fast guy is using 500 pound springs, i want to change from my 700 pound springs to 500's. But your car is 8 years old with high scrub suspension and bias ply tires. The fast guy is in a brand new car with zero scrub and radial tires??????

You can not take a ride height setting for Fat Cats, when you are not using Fat Cats. It will cause all kinds of problems. You must follow the reciepe.

I often do not agree with Jim Daniels, but I also measure to the pinch welds, I am pretty sure Drago also does and most of the pro shops do also. Nothing wrong with measuring at the bump stops, just remeber that bump stops do compress alittle over time. And you need to always be consistent. Wrong but consistent will often give good results.

At that height, you are probably on the bump stops every corner. And the tire is tucked up under the fender so far, causing the tire rub. And the wider Hoosiers will rub even more.

Dave

[FTodaro]

regarding taking the measurement at the top of the shock to the bump stops, I have a pre bent coat hanger that I have for different ride heights. so when I am setting up in the shop i can nail it with little effort I do take a corresponding measurement at the pinch welds so that when I am at the track and need to make adjustments I have some point of reference. But if your car is not totally level when doing this with your ballast in the car its guessing anyway.

[juliancates]

Thanks guys, I'm slowly starting to understand. So, the '99 hats will essentially allow for more shock travel. And the FCM kit provides an alternate bump stop kit that has different compression characteristics if you do get into them. Makes sense.

Sorry to be such a noob, other than trying the different wheels (and quickly switching back) I've basically run this car as it was when I bought it, setup-wise. I've only had the chance to take it out for a couple of weekends so far, and now I'm trying to learn as much as I can about setting it up so I can optimize it.

As for the tire rub, I don't get any at all running the 38mm offset Koseis. If I should expect to have to roll the fenders with the 25mm or 30mm wheels, no problem, I'll do that and see if it goes away.

I'll also pick up the FCM kit with '99 hats. That much at least seems like a no-brainer.

[davew]

There are 3 upper mount designs that are legal for SM. Original NA Mazda design, 99+ with modified bushings and 99+ with Fat Cats.

The Fat cats will give you more shock travel at lower ride height than the others. It is the best version out there. You can get more camber as you go lower, which helps with fender clearance.

This is a perfect example of buying a cheap car and having to do updates almost immediately.

Dave

[LarryKing]

Nothing wrong with measuring at the bump stops, just remeber that bump stops do compress alittle over time.

As compared to the pinch welds which stay perfectly straight and the exact dimensions regardless of off-track excursions.

[juliancates]

This is a perfect example of buying a cheap car and having to do updates almost immediately.

Which in and of itself isn't necessarily a bad thing. One could buy a donor and build from scratch, buy a turn-key car, or land somewhere in the middle by buying a built car for a really good price and understand that it might need some refresh or modification. As long as you know that going in, and if the price is right, I don't see a problem with that. In my case, I bought a regional champion car, NASA Nationals podium car, with current NASA, SCCA, and MC logbooks for $7.5k. A few hundred bucks to customize the cage/seat, and $350 for the FCM kit with '99 hats plus the opportunity to turn some wrenches and get some hands-on knowledge about what is an entirely new platform for me... I think that still represents an attractive value proposition.

[Glenn]

Quick thread HIJACK..... Wheeler when are you gonna start selling Raybestos stuff?

Back to you......................

[davew]

As compared to the pinch welds which stay perfectly straight and the exact dimensions regardless of off-track excursions.

You say tomatoe, I say potatoe

My point was, be consistent.

dave

[davew]

Which in and of itself isn't necessarily a bad thing. One could buy a donor and build from scratch, buy a turn-key car, or land somewhere in the middle by buying a built car for a really good price and understand that it might need some refresh or modification. As long as you know that going in, and if the price is right, I don't see a problem with that. In my case, I bought a regional champion car, NASA Nationals podium car, with current NASA, SCCA, and MC logbooks for $7.5k. A few hundred bucks to customize the cage/seat, and $350 for the FCM kit with '99 hats plus the opportunity to turn some wrenches and get some hands-on knowledge about what is an entirely new platform for me... I think that still represents an attractive value proposition.

Again, just making a point. See the thread about a newbie looking for a car. Know what you are buying, before you buy.

Dave

[davew]

Quick thread HIJACK..... Wheeler when are you gonna start selling Raybestos stuff?

Back to you......................

Just got pricing over the weekend. Should be up and running soon.

[Glenn]

Just got pricing over the weekend. Should be up and running soon.

Good need new F hubs for the SSM.......

[juliancates]

Know what you are buying, before you buy.

Agree 100%. Saw your post in another thread about the car needing $9k of mods after purchase. Ouch.

Thanks for the tips on ride height, I'm looking forward to getting the new bits in place and giving the mid-pack hell.

[juliancates]

So the FCM kit should be here tomorrow, and I've got some replacement control arms coming in from East Street as well. (PO got into a fender bender in the front left. Repaired body damage, but I can only get -2.0* camber. Another story...)

I've been trying to read as much as I can on this forum and the old SpecMiata.com archives about setup. Makes sense to measure available shock travel, and once set, take some measures at repeatable points on the pinch welds so it's easier to eyeball.

Here's my related question... what to prioritize? I have the ICM string set with toe stick, camber plates, etc. I do NOT have scales or a setup platform, and those probably won't be in the budget for this year.

I'll definitely spring for at least one pro setup this year so I can get it done right and understand what my weights are. I can't really afford to have that done before each race weekend, though, so I'd like to do as much as possible on my own. I plan to make up the home depot slip plates, stacking tiles to level the floor with a water level, etc.

Mike C. posted something that intrigued me back on SM.com. Of course I can't find the post to quote it now, but the gist was that you don't "need" scales. If you instead measure the shock travel and make it the same on all four corners, you'll be pretty close. That idea intrigues me, especially since I won't have my own scales this year. Trying to think about the physics, it would seem to make sense that if the shocks were all the same, then if the travel was the same it would be because the same amount of weight was exerted at each corner.

What do you guys think about this concept?

[Jim Drago]

Well define close? 1%? 3%? 5%? I think getting closer than 2-3% would be very fortunate.. Unfortunately 2-3% is a long way off from any normal starting point.

Get your car set up to 50% by someone who knows what they are doing, lock perches down and don''t touch it for awhile. If you move any perches, record all your changes religiously, so if need be, you can get back to where you were.


Jim

[Keith Novak]

As for prioritizing stuff, scales are actually an investment IMO. Not sure what the going rate is in your area for a professional corner weight job, but it doesn't take too many times before you've paid for a set of scales. I think I paid about $800 for my Longacre set new. I've been using the rest of the linoleum tiles that came in my "slip plate" package to get all 4 level with a couple thin pieces of scrap plywood if I end up doing it on the least level bit of my garage floor. I use a Craftsman digital laser level to set up my pads (get two equal you have a level line, level the 3rd to one of those you have a plane, and then do the 4th). The level can double as a camber gauge using your toe stick but I eventually bought a purpose built CC gauge. Setting up my pads is the biggest PITA so this year I'll spring for some leveling stands. My current ghetto leveling setup does work though and has already paid for itself.

[juliancates]

Keith, so you just use your scales with the tiles for leveling? What about rolling the car on/off etc? I'm looking at all these scale levelers with roll-off pads and such and it ends up being more like $2k once you factor it all in. I know shop time's not cheap for sure which is why I want to do as much myself as possible. If it can be managed with just the scales (at least at first) then I might be able to pull it off.