Hey Guys,

I'm starting a new build. It's a 92 T-Top RS - I've got the car completely stripped and am getting ready to raid the parts catalogs (or websites). I need some advice as to what the best route is chassis wise.

Purpose of the car: The car is intended to be a "Jack of All Trades" in that the motor will have good street manners and the car should ride decently comfortable on the street as well as handle well on a road course, and launch well at the drag strip.

Drivetrain:The motor, trans, and rear end are already done. The motor is a 350 bored 40 over and should make around 425 hp and 425 ft lbs at the crank. I do have a B&M 144 supercharger that may or may not get installed. The trans is a built 700R4 and rear end is a 9-Bolt w/ a 3.70 gear.

Chassis Goal:I'm looking to put the car on a diet so I can add a little weight back (8 pt roll cage, stereo, sound deadening) in without compromising the factory weight. I'm planning to ditch the rear seats, spare tire, and swap out the K-Member with a tubular one, as well as A-Arms. I do not have an unlimited budget, but I do want to do it right with good parts. My question is really on brand. I've been looking at Spohn, BMR, and UMI. Because the car will be a daily driveable car I plan to stick with mild steel as I've heard chrome-moly tends to crack over time in street driven applications - and it's outside of my budget.

The Question: What do you recommend as far as brand and options for the following parts?

K-Member and A-Arms

Roll Cage (I'll be installing it - so I'm looking for prebent)

Subframe Connectors

I haven't gotten to shocks and springs (or maybe airbags) yet. I'm hoping to get the chassis done by the middle of February and then get into the suspension. I have to get the car track ready for October. My dad is building a 1985 S10 pickup w/ a bored out 283 - and thinks he can take me in the 1/4 mile. If he does beat me the supercharge will most definately be installed.

Thanks in advance for any advice you guys can offer.
Brian

 

K member and A arms: What do you think an aftermarket K member and A is going to do for you?
I challenge you to do a search and figure out how many dollars per pound lost you are shelling out for that K member and A arms. Now compare that to a hood, wheels, aluminum heads, aluminum water pump, mini starter and so forth. You will find that a K member and A arms give you one of the lowest bangs for the buck. You will also find that there are no aftermarket k members that improve upon the factory design as far as geometry is concerned. Any arguments concerning strength or stiffness are specious at best.
I have yet to see any stiffness or strength testing done much less finite element analysis on any of them.

Roll Cage: Since you say that road course is a goal be aware that 99% of the prebent stuff out there is for drag racing only and does not satisfy requirements for any road racing organization. Go to the SCCA or NASA website and read their rules on roll cages. You will find among other things, all tubing must be DOM steel, 1 3/4 inches in diameter or better, .120 wall thickness or better, mounting plates must be formed to the chassis and can be no less than 8 square inches in area. Seat must be FIA approved if not it must be attached to the roll cage, just about every bar has a specific installation criteria that must be met. The mounting points for the harness are also specific in this regard. So it's not just a roll cage. You will need a seat, and a harness, and high density fia/sfi padding anywhere a bar can come in contact with the driver.

Your best bet is to construct a custom cage or talk to someone like blainefabrication on the frrax forum. I hear he will ship pre bent stuff out.

Roll cages are one of those things that a lot of people like the sound of in theory but very few are willing to build one that satisfies the requirements of any road racing organization.

SFC, buy or build something with square tubing and install it on the outermost portion of the chassis

 

go with umi for the k member and a arms. they save you around 25lbs and great quality parts ( i have there k member, tunnel mounted torque arm/ crossmember with safety loop). sfc are a must when you dealing with good hp. i went with comp engineering one (more money, but i like the results). my car is almost what you want (the whole jack of all trades idea), but i went in my own direction.

 

LOL. I have never seen a road race car with two big butterflies sticking out of the hood. Should be fun to see.

 

ill have to take a in car shot. its an awesome view from the inside.....lol. running a tunnel ram is harder for any type of course racing, but with the right setup, im hoping to perform decent. oh and this will be my daily driver

 

Somehow I doubt you'll find that a pleasant experience. As someone with a fair amount of track time I can say that even having a 2" cowl hood makes it more difficult to precisely hit apexes. Being able to see is kind of important.

 

if you dont focus your attention to the tunnel ram, it doesnt bother you to much. i had a 4" cowl on my old 89 and i never had visual issues. inside shot. i will get a better 1. this was with my phone:

 

Good afternoon Brian.

We have square SFC's and awesome lower a-arms for your car. We also have a k-member in the works that should be shipping in the next few weeks.

The k-member is a twin tube design and is pretty stout while still saving 25 lbs over stock.

We've done quite a few multi-purpose third gens and can get them working pretty well.

As for which vendor to choose, we build all our parts here in central PA, take pride in our work, and feel our suspension parts are ultra premium quality for a fair price.

Let me know your thoughts and how you'd like to proceed.

ramey

ps: Project-RS, thanks for the shout out and you get the best-pic-of-the-day award!

 

thanks ramey for the honor of being "pic of the day" . just so brian knows, heres the difference between crossmembers and tunnel mounted torque arm.

 

Although I am a sucker for shiny parts, I will agre with pablo that there are much better places to invest money into the car that will yield greater results over a tubular k member. Those places as he listed should be addresed first, the aftermarket k members do provide a lot more clearance around the engine, so if you need room for special components or exhaust routing they. Can be quite helpful.

 

Thanks for the quick responses guys.

Pablo,
The purpose for the K-Member and A-Arms was a combination of weight savings, getting rid of flex (I can't imagine the stamped A-Arms are as stout as the aftermarket tubular ones are) as well as getting a bit more space in the engine compartment. I agree they are quite expensive and the weight savings per dollar isn't great. I'm going with full length headers this time around and am toying with the possibility of a twin turbo setup down the road, so having the extra room is important.

As far as the roll cage - I'm not planning on registering SCCA, I just wanted the car to be able to handle well. I know there are quite a few SCCA amatuer races that don't require a cage at all. For fully sanctioned races I think they actually require a 10 point either way and I don't want a 10 point, it takes up too much room and would take away from the aesthetics too much. The cage I'm looking at is by Competition Engineering its 1-3/4" O.D. x .134", so that falls within the material requirements, but it doesn't have a upper or lower front hoop because it's only an 8 point. It is NRHA and IHRA certified, so thats one plus .

Thank you for your advice on going with square tube SFC's that is the route I will definately choose. I was looking at Spohn Performance's round tube design, but it does make sense that the square tubing will be stronger.

Project-RS,
Have you had to pick any small birds out of that thing? Good lord! Very cool looking setup. I did look into UMI performance's K-Member and A-Arms and am considering them, but... and I direct this question to Ramey as well, is the second tube absolutely necessary, as I stated above the extra room was a big deal for me and comparing the UMI Performance unit to the Spohn unit, that extra tube appears to take up the same amount of space as the factory unit.

I will be purchasing the UMI SFC's, they look beefy and with a T-Top car the extra structural integrity is definately needed. I do like the UMI crossmember, but I may have to fab my own depending on what I'm going to do for exhaust. I haven't decided on single or true duals yet. I'll figure that out when the chassis work is done and the engine, trans and headers are in place.

Thanks again for the feedback guys, I really appreciate it. If anyone else has any additional ideas, I'd definately be interested in hearing them as well.

Thanks again,
Brian

 

//<86TA>\\,
I agree, and am thinking that the K-Member is going to be the last thing I buy before the motor goes in. That way if I run out of money before then I still got the major stuff done.

Thanks for your feedback!
Brian

 

Its always been a good thing to read the post when started.
like the part he post about

Purpose of the car: The car is intended to be a "Jack of All Trades"

Just me..

adding the K Member and A arms is part of some of the mods you can do now. to drop a few LBS off the car.

start off with the things that are the most bang for the $$

back in 1993 when i was running mid 10s with my 50 state smog Z28
thank you "John Lingenfelter". MY CAR started going faster has pounds started coming off. everything from plastic Head lights. to AC to just about every thing i did not need.

Now today with all the other parts in the Aftermarket that are made for the Third Gens you can drop even more Pounds.. it all adds up.
(my car has dropped another 80lbs)
(added 44 more cid)
(added boost)

the jack of all trades car. has its place. and like any car we bolt together it's Fun... Remember..it's fun.. Right?

I my self like the cars to look good. inside and out..
pull the wheels and run hard..thats me. thats what i like.
it's all about the fun.

there are alot of Guys on this site with alot of info.
some..with the not so right info.(others with alot of good info). if you know what you want. and what you like..then just do it. remember. it's all about Having Fun!

and this is how it starts. by asking.

 

Project-RS,
Have you had to pick any small birds out of that thing? Good lord! Very cool looking setup. I did look into UMI performance's K-Member and A-Arms and am considering them, but... and I direct this question to Ramey as well, is the second tube absolutely necessary, as I stated above the extra room was a big deal for me and comparing the UMI Performance unit to the Spohn unit, that extra tube appears to take up the same amount of space as the factory unit.


sorry, no birds yet.....hahahaha. ill post pics of my sfc from competition engineering:





my good friend tim welding up the sbc. he owns a 1000hp 81 camaro (all motor bbc)