killav

I think I found the problem. Go to page three for explanation and pics.

Mike

For anyone needing a refreshment on my problem, check out the thread below.

https://rennlist.com/forums/928-forum/289911-torque-tube-swap-was-succesful-but-i-still-have-a-rattle.html

I sent my converter off to get rebuilt due to a nagging rattle that I cannot get rid of. I decided that for the money, I would go ahead and have the converter opened up to make sure nothing was wrong. Long story short, the converter turned out to be fine. No excessive wear/loose fins or anything like that. The shop commented on how robust this converter was for a factory converter. The hub had furnaced brazed fins and the stator looked really beefy. The only thing that could make these converters completely bullet proof is to have the fins on the turbine furnace brazed as well, which they were not. I had him trim the turbine fins slightly for a 300 to 400 rpm rise in stall speed. I will let you guys know how much this affects the driving experience. My converter was on the low end of the spectrum as far as factory stall speeds are concerned. In other words, the converter felt "tight".

The place is called Texas Torque Converters located in Big Spring, TX. Phone number is 432-268-3737. Ask for Rick. This guy really knew his stuff and the price is very good. He had all of the needed parts in stock (which is not very many). The main cost comes from the labor and very expensive equipment required to cut and re-weld the converter housing back together with very little runnout. Expect to pay around $150 to $200 for a rebuild and stall alteration if you wish. Straight rebuilds might be cheaper. *Your price may vary*. My converter had virtually nothing wrong with it so the price reflected this. Total turn around time was about two days at his shop plus the time in transit. I asked him if I could let you guys know about him and he, of course, didn't mind and really appreciated me passing this info on. I have no affiliation with this guy and basically just stumbled across the phone number on the internet. I should have the car together by the end of labor day weekend and be able to let you guys know what I think.

Loaded

Please let us know what the flash stall is and what the brake stall is.....Thanks!

killav

Current brake stall speed is no more that 1700-1750 using the factory tach, which might not be the most accurate, but it's all I got. Basically, I stepped on the brakes with some decent force, floored the throttle in a progressive fashion (not slow but not fast either), by the time I got to the pedal to the floor, the rear tires would slowly break loose and spin very slowly. I applied the brakes with just a tad more force, and the tires stopped and I was at the above RPM. I didn't do this test repeatedly because of the stresses involved in the drive-train. Obviously, this is not the way to launch the car at the drag strip. The proper way of launching by "flashing" the converter was not tested so I won't have a before reading for this.

Randy V

I know what brake stall is, but what's 'flash' stall?

killav

Edit, I did a search on the net in order to find a better explanation than I could type myself.



Converter Stall RPM: The engine rpm that a given engine will reach at full throttle with the drive train locked.

Converter Flash RPM: The engine rpm that a given engine will reach at full throttle at the point the vehicle begins to move with no brake application. Both stall and flash must be checked from idle speed.

Many drivers bring their engines up against the converter almost to the stall point. While this may help their reaction time, it usually doesn't help the ET on milder engines. By leaving at a fast idle, or as slow as the engine will run and not bog when the throttle is quickly opened, the car may actually launch harder because the converter will flash several hundred rpm higher then the stall speed. The engine is still accelerating when it encounters the converter load (rather than being at a fixed stall rpm), and it literally yanks the car to start.

Loaded

Exactly, to drag race a 928 auto you need to flash the converter for best launch results. I have found that if I flash the converter i.e. stand on brake and release and stab(1/2 throttle) the the 928 will launch very hard, With the the converter brought to the stall speed it does nothing but make the BOG or react sluggishly. Thats why autos seem to launch and feel better with more ignition timing and low end torque(stock exhaust no RMB for me) Most drag races are won off the line

PorKen

Hell, yeah! I can't drive with less than 4° cam advance (and about 31° ignition) anymore.

I noticed I've developed a 'twitch' whenever taking off - I unconsciously blip the throttle to flash the converter, then throttle up from a lower point - all in one motion.

ROG100

Flash Stall - the moment you bottle out of flashing and realise it is a criminal act!

SMTCapeCod

Way back machine strike again....I remember posting a shop in NJ that offerred several stages of T/C upgrades and it was met with mostly resounding silence and a smattering of 'duh..why would you wanna do that..". I referred some to Rennsport (since the trans is Merc). Nice that times have changed now though.

SeanR

Hey Mike,

Did it fix the marbles?

ROG100

And are you coming Saturday morning?

killav

Well,

As you know my car is in a thousand pieces, and I have one more day on the A/C system that I am installing for a buddy of mine. So my Saturday will be split between finishing up the house and then continuing to put my car back together. I will not miss next month though, even if my car is back apart again for something else, like motor mounts, GTS Baffle, Real pan gasket, Stereo upgrade, Paint Calipers, ect....ect....ect.... LOL.

Thanks for the invite.

bcdavis

I thought Keith had it done on his '82...

There was a thread about it.

A place in the valley that was doing it, at a very reasonable price.

928SS

it cause nobody likes you. hahahaha/just kidding. I also did mine at a local shop before the stroker and it made more off the line diff than the chip/rmb put together/pulled like a train from the start w/no wind up/lag time anymore

not that nobody really cared much/probably cause it's a PITA to do (remember the $200 for the converter is on top of the R&R), and we've never posted before and after 60' times/so it's all just anecdotal info but I'd recommend it to anyone doing a torque tube/trans OH.

had 3500 stall on a street racer car of mine as a kid - it was uncontrollable to start off under anything less than straight line/dry conditions. had to "bump" it to get it rolling otherwise. I think around 2k/2100rpms is a nice balance between ripping your head off and being able to smartly pull off the line w/out special efforts...

enjoy!!

bd0nalds0n

I had mine done by Edge Racing Converters here in CA. Greg sent it off while I was having a torque tube rebuilt. I think it was more than $200, though. Anyway, I'm happy with the result, although I had it done when the car was still NA. With the SC it's very easy to spin the tires off the line, and I'm pretty sure increasing the stall speed made matters worse, but I s'pose if you can get off the line with barely spinning them it's better to be in the meatier part of the torque curve.