well, im new to the site and would like to say hello to all my soon to be tranny gurus. and now ill start with the rundown and give you a link to see the car that I entered last year.

http://jalopnik.com/5041139/the-top-...ns-new-england

I have a 1991 firebird with the crap LO3 V8 and a 700r4 behind it. we went to the 24 hours of lemons last year and made a hell of a run. they docked us 30 laps becuase the promoters felt the suspension was too stiff and i had replaced suspension components. which was not the case. but what ever.

we ran well and suprisingly the bird was competitive around the track. we ran into some mechanical gremlins and the rad blew off an end tank roughly 80 laps in. which was replaced. then the transmission went south and started shifting only when you feathered the throttle at 6k rpm. we made it through roughly 90% of the race and then transmission would not shift at all. the car would accelerate, though it was definatly slipping in first, and it felt as if it would lock up and give full power at around 5k rpm till the engine signed off at 6k rpm.

we are returning to do the pontiac right and show that japcrap is just that.

on the list of things to do is throw away the rear end with its 2.73 open diff and swap in a 3.73 with posi. that should help us get out of the corners with a little more authority. my problem lies with the transmission.

the tired 700r4 was not up to the abuse. and im wondering if even a rebuilt R4 is capible of withstanding the tracks abuse. its a tight course with corner speeds in the 30-50mph range. which is alot of 1-2 shifting and the occasional third gear romp on the banked corner.

i had my sights set on a TH400, but its looking to be an expensive swap with purchasing the tranny, rebuild, new driveshaft and associated crossmember relocation...

the TH350 with a 9" tailhousing looks promising because you wouldnt need a new driveshaft but do you guys think that it will handle the abuse without a full on race rebuild?

so im asking in your opinion with roughly $1500 as a budget which of these scenarios would you choose as a reliable option to get the car thru the race and see the checkered flag in first. if you guys can help i promise that ill give you the hood of the car for Thirdgen.org's banner.

 

Come on guys, no one has any insight? im asking for your opinions, there has to be someone willing to shed some insight into which option is best?

 

first, even if you use a TH350 with a 9" tailhousing, the 700R-4 driveshaft is the wrong length. Second, for about $1300, you can get a level 3 700R-4 from www.700r4.com, that's rated over 620 ft-lbs. Your 305 doesn't make half that. Changing your axle ratio as you say will keep you out of first gear more. At that point, use a 4.10:1

 

i see a level two for 1295 is that the one you meant? maybe i was a little decieveing in my statement "$1500 as a budget". that means total, including the purchase of the rear end and i still have to get a torque converter for the new transmission. and this brings up my next question, what type of TC should i be using for a road course application. I have to do this on a budget, which mean money is always a problem and my race team doesnt have deep pockets... so for 1500 bucks total what should i do to get this thing to the end of the race?

do you think a generic rebuilt 700r4 for $700 will make it? i know i have to buy a transmission, rebuilding the current one isnt going to happen, we drained the fluid after the first day and there was plenty of metal flakes and clutch material in the fluid... did i mention it wasnt fluid any more.. more like sludge. amazing what 8 hours on a road course will do to a 135,000 mile transmission.

 

I'm a long way from any kind of expert, but from just looking around I would say the 700 rebuild is going to be your only budget option. Anything else looks like it is going to take you over budget (which is not an option since you have a balance of only 1500.)

That should leave you enough in your budget to get the 3.73 Posi.

TRG

PS. Saw this posted on the comments portion on the website you posted:

NovaloadMissesPolar
12:29 PM on Mon Aug 25 2008


I think the Bail Bonds ad on #3 is wonderful.
But what's the deal on the Firebird? That thing looks mint. They must have had quite a b.s. story.


huh?

 

haha, my BS story...

well i bought the car off craigslist for 450 bucks. the car had been in a front end collision... not that he told me, but it didnt take a genius to see the mis-matched gaps on the hood and fenders (who cares its a lemons car). later on i found some real carnage under the rear carpet. the guy was a hack too. he desimated the sheet metal looking for the fuel pump. 4 exploratory cuts plus some serious ragged edges. i couldnt believe it. but we did some work. needed a water pump baddly, the car would over heat if you kicked it down a gear on the highway to pass some one. the car pulled to the left hard when you hit the brakes. (turned out that the same moron who cut up the back sheet metal twisted the flex line when installing the caliper). the interior was clean and had some bitchin' tribal floor mats! we gutted her, dumped the seats and interior parts. stripped the seat belts and airbag. installed a race seat, roll cage, new brakes, 225/45/15 hankook tires, a straight length of pipe in place of the cat and a functional hood scoop. other wise the total price of the car getting it to the race was $493.80, this is not including the saftey equipment mind you. total cost was in the $3,000 area.

we sold the cat to a scrap yard for 75 bucks, and the pioneer head unit for 50 bucks. that gave us the money for straight length hood scoop and a few tune up parts.

i went and held true to the rules last year. the rules are stated that any modification not related to safety equipment is considered in the cost of the car. but after getting passed (more like left in the dust) by a "500 dollar" bmw 318 on the banked corner of the course (fasteest area), i know that all that price rule means is dont get caught cheating.

so i arrived here. looking to make this car a sleeper.

 

id go for anything bowtie overdrive makes.
http://www.bowtieoverdrives.com/cata...php?ITEMID=681
this is SUPER NICE, but at $2000, you cant afford it i guess.

a th350 would hold up well and are usually more sturdy.
just make sure you get one out of a v8 car like a truck or something.
the v6 models are much weaker.

once you get it, do a shift kit to tighten up the shifts and throw the biggest tranny cooler you can find on it.

i got one for my camaro that measures 10" x 20" x 3/4" for like $70 from summit.

the th350 has a 2.52:1 first gear vs the 700r4's 3.06:1 so you would definitely need a different rear end


http://www.atiperformanceproducts.co.../350/index.htm
here are some nice th350s if you want to go new, which i would suggest for the price.

the tranny cooler is a must though...
the shift kit is as well.
you want to reduce any slippage and heat to keep it running strong.
otherwise your parasitic loss becomes huge.






as for the converter, id say keep your stall around 2000 or so.
lockup isnt necessary because you say you are hardly ever in third gear anyway.

 

Sounds like a fun time at the races. My 2-cents worth is to use a TH350 and add a large tranny cooler. I can't see any reason to stay with a 700R4. It'll just cost more all around.

With the TH350 the rear gear ratio selection will be between the required top speed and how much low gear is required. Remember that the L03 has low RPM torque, so don't go too steep on the rear ratio.

RBob.

 

Stick with the $500 program or build a real race car. Besides, if someone from your region finds this post, the car will just get crushed or purchased from the organizers.

 

well the $1500 budget has alot to do with 500 "program". the car was given a residual value of 0 by the promoter. I still have all the glass from the car and the working window motors along with some other goods im gonna flea-bay to knock off money from the total. while it would be easy to just lie i still have some integrity and will hold as close to the rules as possible.

its not impossible for me to sell the existing rear end, glass, window motors, dash board, heater core, AC compressor, and what have you thats left on the car to get the total purchase price of parts around 500.

so im not totally cheating. but like i said the mazda miata that won the race was really freeking fast for a 500 buck car. and dont get me started on the bmw 318 that smoked me on the banked corner. there were plenty of marginal cars. and if they crush it so be it. and if they purchase it they'd be doing me a favor, lol this racing thing is very addictive.



****If you found this post and insist on using it as proof that No Budget Racing is cheating, well kudos to you for having no life and being a sore loser! ******

 

The TH350 isn't very strong, I've broken every one I've ever had. I've bought used TH400s for as cheap as $5, but you should be able to get one from your local version of Pick-N-Pull for $75. If you look every week, you might come across one that was recently rebuilt.
With the taller first of either TH, you'll be in first gear more of the time, but it's not drag racing, so a taller first gear might not be all bad. and if you search the salvage yards, you'll find all of the following gear ratios for the 7.5" axle: 2.294:1, 2.412:1, 2.563:1, 2.733:1, 2.929:1, 3.077:1, 3.321:1, 3.417:1, 3.727:1, 4.100:1.
You mentioned you did alot of shifting between first and second with your 2.73:1 axle and 700R-4. First gear is 3.059:1, and second is 1.625:1.
Now, did you ever go to third gear? If not, a bit of basic math should help you find which combined ratio would solve your problem.
the TH400 has ratios of 2.48181818:1 first and 1.481818:1 second, while the TH350 is 2.5151515/1.5151515. The 200-4R is 2.7405404/1.567567567
This should help you dial it in.
As for a torque converter, you're not gonna benefit from a high-stall, so just be aware that most stock GM converters slip about 400 rpm at full throttle in gear.

 

not to discredit you atilia, cause i truly believe you know what you are talking about, but were your th350 failures due to the transmission just eventually quitting over time or was there a catastrophic failure?

most of the time, th350s just quit working because they shift sloppy and generate lots of heat.
a shift kit and a massive tranny cooler will fix this problem. easy...

this transmission wont be doing much accelerating from a stop so i find it hard to believe he will snap anything.

the only thing i have against the th400 is that it has a bigger rpm drop from first to second gear, which is harder on a transmission (in general) than a smaller drop in rpms.



to the OP, if you shift the car manually, you can get a lot more out of the transmission. you may loose a few 1/100s of a second here and there, but the transmission will not gear hunt nearly as much.

also, with a th350, there is a kickdown cable that if you are going to shift it manually, i would disconnect. just be sure that if you disconnect it, it is tied off somehow or it will get stuck in the throttle linkage (ask me how i know this...)

th350s are also VERY common in junkyards.
if you pull one, try and find one from a car that looks like it was taken care of. check the fluid too.
wouldnt want to spend money on a beat up trans.

 

about the manual shifting. As to the rpm drop, If the OP can find the perfect combined ratio, (trans and axle) it might eliminate shifting. As for the RPM drop, the TH350 and TH400 are so close you can't tell it without doing calculations. Both are way closer than the 700R, and the extra strength of the 400 negates this. the 400 does eat the most power, however. I've only ever spent time with one 400, and didn't love it.

 

atilla, if i were to go with the TH350 do you know off hand what driveshaft length i would need in order to do the swap? i found a place on line that sells used nascar driveshafts in a variety of lengths from 40" to 55" for 75 beans.

any thoughts on this.

 

i think it would need to be 1.5" longer...
measure it with a tape measure.
ask them where they want the measurements from, but usually its from u-joint pin to u-joint pin on center

 

ok so using a calculator i found online i figured this much out. lemme know if the figures sound right to you. i assumed to only be using the second gear in the transmission to alleviate the excessive shifts and try to milk as much as i can out of it. i know from the lap charts that the average speed attained was appx 55.32 mph. id have to assume we were topping out around 65-70mph on the banked corner before the chicane.

Over all diameter of my tires (225/45/15) = 22.97"

top engine speed to be in the neighborhood of 5500 rpm all though i can rev it out as far as 6-6.5k if needed.


TH400 -
w/3.43 rear will give me = 73.97 mph
w/3.73 rear will give me = 68.02 mph

TH350
w/3.43 rear will give me = 72.35 mph
w/3.73 rear will give me = 66.53 mph

its pretty obvious that a 3.73 rear will be too steep and require a shift on the banked corner in order to attain the approximate speed. with the th350 at 2500 rpm ill be around 32.88 mph and the 400 at 33.62 mph. which is in lower range of cornering speeds.

so this boils down to reliability and ease of installation.

which one boys?

 

the th350 is lighter and can be made just as strong.

 

I just took the short-tail TH350 out of this '82 Camaro I just dragged home, and the driveshaft is 44 5/8" center to center. You can have the driveshaft if you'll pay shipping. PM me your zip code if you want me tofind out how much it'd be.