I'm pretty sure I know.

Went to the track last friday for the last TnT of the year with my schools mini-baja club. The first run I was the first car down the track and I was on street tires, the track just looked greasy. I was lined up with a pickup, I launched normally and spun to the top of 2nd, the pickup actually pulled ahead until I pedaled it and got traction. That was a 15.0 at 105.

Second run, time to get serious. I told everyone how it was a consistent low 13/high 12 car and then proceeded to run a 15, it's on. I put the ET streets on and warmed 'em up real good. I launched the same way, it dead hooks. Second comes, dead hooks into second(normally a little spin and a little sideways). It was a good 13.0 run. As I made my way back to the staging lanes and came to a stop I heard this terrible metal on metal grinding sound, immediately put it in park and it went away, put it back in drive and the sounds back and the car wants to stall. I drove back to the truck and showed my dad, he agreed that it was done. Luckily he had AAA and we got it towed home for free.

The car was a touch faster through the 1/8th than normal for a 13.0 run so my guess is that the converter died somewhere around mid track.

We just dropped a th350 off to our trans man for a little love and a 3000-3500ish converter.

 

sounds like a cracked flywheel sorta

 

Well then I get a 3000-3500 stalled th350 and a new flywheel.

I thought of that too, but then why does it wants to die if I put it in gear.

 

Doesn't sound like a converter problem if the noise went away when you put it in park. The converter will constantly spin while in gear or park. Sounds like an internal tranny problem. I've had some bad converters and they've never made any noise.

Pull the pan to see if there's any hard parts in it.

 

I can't right now, it's at a friends place(has a lift), but I'll make sure to once I get it out.

Would it still drive and shift though?

My theory was that the fins in the converter don't have a load on them in park but do in drive and that a few loosened up or broke partially and only make noise when a load is applied. I might be completely off though.

From what I hear the th350 will be done by the end of the week.

 

I knew when mine broke, sounded like a shotgun blast. It split open spraying the road down with a 3 foot wide, cool looking spray pattern of a turning converter. Did this with the 305 in the car and stock trans.

 

No load on the fins. They are part of a fluid coupler. Oil is forced from one side to the other like a desk fan blowing air against another desk fan causing it to turn. The faster the first one turns, the more air is forced across to the second. The first fan can never stop turning.

A converter works very similar. The 2 inner halves of the converter which represent the desk fans are very close together to reduce fluid loss between the 2 halves. They ride on a torrington bearing. If the bearing got crushed causing the fins to make contact, they would make noise all the time.

There's also a sprag inside the converter. It acts like an over-running clutch. Locks up in one direction and free wheels in the other. If this fails, usually by self destructing, the converter usually has a 100% failure and won't work at all.

Before I would assess it as a converter, I would pull the pan first. Although converters can fail internally, they need to be severely abused before they do fail. A low 13 second car would break something in the transmission before breaking something inside the converter.

Just from the sounds of "putting it in park and the noise went away" tells me it's inside the transmission. The parking pawl stops an output drum and taking it out of gear takes the hydraulic pressure off the direct clutch pack or band giving a neutral gear.

Either way, the tranny needs to come out. Even if it's a bad converter, the tranny will need to be stripped down and cleaned. If you don't care about the old converter, have the case cut open and take a look inside it.

 

Thanks for explaining that, I had a decent idea how a converter worked and you just cleared some things up.

By load I meant the load of the fluid on the fin, similar to how a flex fan works.

The guy that built it wants to do an autopsy on it, so we'll find out what broke. I'll probably cut the converter open, it's a stock piece so I don't care too much about it.

Is going 1st to 2nd in the burnout harmful?

 

on stock stuff, i'd say yes. get that th350 built with a 36 element intermediate sprag to reduce the possibility of breakage during a 1-2 shift in the burnoutbox.

 

1-2 on a burnout is hazardous to most transmissions. The TH350 would be the first to fail. A TH400 with a 9 element sprag would be second. The stronger 34/36 element sprags will take a lot more abuse but can still fail.

Actually 1-2 isn't what's bad. It's being in 2 when you come out of the waterbox and hit dry pavement. When coming out of the waterbox, you want to be in high gear.

 

I'll talk to the transmission man about the 36 element sprag.

I thought you weren't supposed to be in the water when you did your burnout, but you were supposed to just roll through onto dry pavement and then do your burnout.

 

OK. Dryer pavement. It's the sudden stop of the wheels spinning when they hit the dry pavement that causes the damage when in second gear.

 

Gotcha...

So I guess the next question is what will it run with say a 3200 converter in the th350. I've run a best of 12.90 at 108.6 with a 2.0 60'. As it turns out my track has one last TNT this sunday.

 

my money is on the sprag being cracked/imploded...be sure to update with autopsey results...been there done that and had similar symptoms, got so bad engine would not rev over 3K and made gawd awful squeeling noises too. but it started out just like yours and gradually got worse as we tried to figure out wtf it was.

definately upgrade drum/sprag, definately come out in 3rd gear. Coming out of the burnout box in 2nd puts the entire shock/load on the sprag which is already a week design from the facotry anyways, shock it enough and tangs will sheer off. When you come out i high gear your doing many good things.

1. lower engine rpm and higher tire speed which equate to shorter burnout duration to achieve good tire temp

2. your coupling all the guts of the entire tranny into one strong unit so shock is much less sever, and when it does dead hook pulling out of the box, since your in high gear it will load the converter and flash converter insted of sending shockwaves through tranny.

you ought to pick up a little bit with new higher stall.

let us know what you find out, even on factory converters it is very very rare to lay fins over/bust fins...sprag is about the only other component inside that is known to go bad.

 

Trans will be in the car tomorrow, I'll up update with how the car responds to the new converter and trans and what broke in the 700.

 

Got the converter and trans in and went to the track today, the new converter is a 10" tci of some sort that flashes to around 4000. It made a BIG difference in the way the car launches, it also made a small bog I had way more noticeable.

My best run was spinning, then bogging.
.548
1.81
5.212
8.065
85.92 mph
10.544
12.642
107.44 mph

My MPH is down a little, but the air might now have been as good or the converter might be soaking up a bit more than the old one

 

Is the bog fuel slosh coming out of your vents on the carb, or do you run a edelbrock style carb?

if running a holley, try running the rubber fuel line from the front vent to the back vent on the carb, and cut a slit in the top so they can still breath...often times when they launch the fuel runs up outta the vent tube and splashes right down into the carb flooding it for a split second and producing a bog.

 

surprised your only pulling 1.81 60 foots with that stall and that engine power... you should be a good deal quicker than that

but nice gains everywhere else with that new converter.

 

i think he's running "radial slicks"

 

Yup, and a completely stock suspension with monroe garbage shocks.

I'll try the fuel line on the vent tubes, I'm not sure if it's fllooding, how would I tell? When I launch the car jumps, then dies and comes back to life.

I think it's a pump tuning issue, it's got .040 squirters and a red cam. The car will stumble going down the road and rolling into the gas.

 

I dunno, with all the engines i've had and the many many carburators...same with all my drag racing buddies that street/strip like i do, i've never ever had to mess with the cams on the pump shot, ever...i think guys start digging deep looking for answers or bought a used carb, something to that affect, i dunno, but try the slosh tube trick first and see what happens...are you running an electric fuel pump or mechancial, is your fuel system dead headed or return regulated, are you running a carb spacers-if no, why not, if so what type of material is it, if aluminum get it out of there and buy a plastic one.

Start simple before you start tearing stuff apart swapping squiters/pumps/cams and possibly opening up even more problems...KISS principal for now. lemme know about the ?'s i asked above.

 

It's a used carb, mechanical pump, no regulator, no spacer(no hood clearance). The carb came with .025 squirters and a green cam.

If you need anything else, just ask.

 

that's a huge pump squirter! i think i'm running a 31 or 33. i don't think you're sloshing the fuel...not on a 1.81 60'. i think you could go down in size on the squirters (and this was my original thought when you described the problem) and you'd see the bog go away. go back to a stock or near stock accelerator cam position too...you might just be suprised!

 

With the .025 squirters it still bogged, I think I'm going to try the .025 and the green cam. I never ran it like that when I got it.

 

Mine did...with my old 355 and 830DP, but i was running DOT slicks, not radials, so that's probably why

And i agree, step down the squirter/change cam; your dumping an awful alot of fuel with current set-up and obviously the engine cannot handle it all in like that.

 

stock suspension kinda kills your times but get that bog tuned out and you should see 1.7's easy

 

Charlie does'nt post here anymore since he bought a digger and has moved onto bigger things, but he was in the 1.3? range on stock suspension and running consistently...these cars are set up pretty good in factory form...i just dont like the torque arm on the tranny deal...

 

Tomorrow I should have some time to play with it, I'll see how it responds and report back.(it's kinda hard though because anything more than 1/4 throttle blows the tires off )


Maybe I should start a thread in the carb section.

 

ever find out what happened with the old tranny?

 

We never took it apart because we're pretty sure it was the converter. It wouldn't spin freely but the tranny seemed ok and would turn.

 

cant wait to see some improved times! you'll get that car moving for sure

 

Thanks, I'd have done some testing today but it was raining and wouldn't have shown me anything.

What are the plans for your car? Cam, heads?

 

mine? i'm gonna add some 1.6 rockers to see if they help at all for this year. then december will arrive and racing/driving season is over. During storage i'm gonna either port the heads and add a cam or just port heads. i really want a cam tho

 

save your money!!!!!!!!!!!!! i cannot emphasis this enough, you will not see any gains going to 1.6's use that money to put into the head porting, different cam, gaskets, whatever, but dont just throwo your money away on a proven pipe dream. Using 1.6's is fine if your doing a fresh build and need to buy rockers anyways, but to swap from working 1.5 to 1.6, your literally throwing money in the trash since you will not see any gains....if you "feel" a difference, it's because you want too, and pay special attention to the air if you run it anymore this year, if you run in similar conditions as you did/do with the 1.5's, you'll understand your alot lighter in the wallet for nothing at all other than to say you run 1.6's.

 

well i'm giving it a shot. going from .415/.430 lift to .443/.459 seems like 10 hp to me but we'll see. the hsr out flows the heads so the heads are now the bottle neck. abit more lift should help considering flow numbers i've seen posted for these heads stock. they peak at near .500 lift in flow

i plan on having it done by next week and hitting the track possibly by sunday oct 27 if i have time..but for sure on NOV 3 and 10th if the weather is good. Not sure if i'm going but Dyno day is Nov 3 and i could put the stock tune i had in it the day of my last dyno run to see how much the 1.6 rockers help. then put in the modified chip i use now to see how much power i gained...but the weather should be cooler so i expect abit more power regardless.

I will definately keep you posted either way

 

I kind of agree with IHI, but since you're going to get a cam and head work you would probably need new rockers anyway.

If you port the heads, get a cam or you'll be missing out on a decent chunk of power. Even something mild would be better than stock.

 

I think your guesses are exactly right, in the 5-10 hp range, to see anything on a track your going to ned a solid 30hp gain. you could try to use the off the hip math of 100hp equals 1 second and break it down into each 10hp is a .01...but i promise you will not see 10hp anywhere on the track, not even 20hp....unless your motor is as bone stock as can be, then you may notice something, but with yours dont expect anything but lighter wallet

 

not trying to get off topic but i think you'll see some small gains with 10-20 hp difference. i want to believe my HSR only gave me 20 hp and i saw a huge difference but i guess that was from shiftin the power curve

and the weather changes alone make a difference. ARe you saying weather alone is taking away 30-40hp and thats why i'm seeing 1-2mph and 2 tenths difference from hot and cold days? i would think its only 10-20hp

I guess i'll find out. i only plan to run these for alittle while just to see if they work and hope i can get that much closer to 12's on this bolt on motor

 

What i'm saying is you can read hot rod all you like and let them tell you spending all that money and wasting a few hours of your day is gonna pick you up....the reality is, it does'nt and wont. i'm not talking about the guys that are just test and tuners, i'm talking real life bracket racers that know what their cars run all season that have tried it for sake of experimenting...guess what...nobody saw a thing anywhere, and that is why i'm so adiment about having you put that money else where...cuz you will not see anything on your timeslip. Mags can say all they want, real life on track performance is where it's at...that is all i'm saying, but it's your money/time to do what you like, so give it a shot

 

well i was plannin on using them for short time and selling them since i dont want 1.6's for my cam swap unless its a hotcam which i'm not getting so we'll see