Johnny5

iTrader: (2)

Late last season a TH400 RMVB was put into my TransAm. Ever since it has had some issues that are driving me nuts. Some of this stuff was either used or entry level parts and I can't help but think that something is just not right with the combo.

1. The thing seems to get really warm even though I have a cooler. The cooler is small and mounted parallel to the ground in front of the passenger wheel. I also have a gauge but need to hook this up.

2. The stall was great when racing NA but spikes up to like 5500 rpm on the 150 shot. My rpms never even drop much on the bottle so that makes me think I'm missing all the torque off the line by jumping right past the meat of the powerband.

3. There is a very nasty vibration around 55-60. I've rebalanced the shaft, checked pinion angles etc. and it still is there. I don't know if it is something with either the flexplate, the converter or the LS1-TH400 style flexplate. Something can't be right there. I'm wondering if this just took out the front seal.

4. It drives find around town and as soon as I get to the track the thing starts to leak and drip onto the header leaving a nice smokey trail. This is really pissing me off. It looks like some from the vent tube and some from the inspection/cover area which may be the front seal or pump area.

Where do I even start? I have no experience with transmissions but have figured out the rest of the mechanics on the car.

Gilbert@Ace Racing

1. How warm? How do you know it's too hot if your gauge is not hooked up?

2. The converter is too loose.

3. Transmissions very, very rarely emit vibrations. Converters are usually balanced. Check the flexplate, check the mounts. If you have a Poly trans mount install a factory mount.

4. How much fluid is in it? It could be overheating causing this problem... get the gauge hooked up and get back to us.

g

trans2000am

iTrader: (49)

i thought a stock mount will cause the shaft to break in are cars????

Gilbert@Ace Racing

What shaft and where did you get that information?

g

trans2000am

iTrader: (49)

maybe it wasnt the shaft but that a stock mount will cause something to break or throw something off i thought i read that on one of the stickies

Gilbert@Ace Racing

If you can find that I would be very interested to read it and offer an opinion.

In my extensive experience I have found that a stiff transmission mount is detrimental when used with stiff engine mounts. In these F-Bodies at the very least there is a significant NVH transmitted into the chassis and subsequently into the passengers cabin when a Polyurethane tranny mount is used with stock engine mounts.

Sorry for the .

g

trans2000am

iTrader: (49)

this is what i was talking about

Mount-
Do not use a solid tranny mount. It will crack the case or the bellhousing the first time you leave hard.
Use a GM mount or an energy suspension mount # 3.1108(G/R)
Dont skip out on replacing the mount, it is cheap and pays off

sorry for thread jack

Johnny5

iTrader: (2)

Thanks a ton for the replies.

First thing I'll do is hookup the gauge. You are right, since I don't have a number so that is just jumping to conclusions.

I still have the factory motor mounts. What is the preferred motor / tranny mount combo in your opinion? When the motor just idles it shakes pretty good so I was thinking about putting something other than the factory rubber mounts in there.

As far as the converter goes, I was thinking I need something more in the 3200 range. It may be slower N/A but seems like I'd be right back in where the extra 200ft/lbs kicks in off the line. There is a ton of talk about best converters on here but it is all for the stock tranny (4l60e). Coan, Chance, Vig and a few other names tend to show up via search for TH400 tranny combos but I need to get some more info on a rock-solid converter option for this car.

Should I be using the flexplate with crank adaptor or just getting one that is made for an ls1 mating to a TH400?

Gilbert@Ace Racing

Because of the power you are making I would recommend using solid or poly mounts at the engine and a factory rubber style mount for the transmission.

As far as the converter goes, give me a call. We can built you a very efficient unit that would serve your needs well. Once we had a very good understanding of your combination we could move into the build... typically we need only 1-2 days before shipping it out!

Take a look in at the thread below, the 9 1/2" converter depicted there is what we would build for your combination. It would need an anti-ballooning plate. But other than that, it would look identical to the unit there. And yes, it could be built with the correct Pilot Hub so that you would not need to use an adapter.

https://ls1tech.com/forums/showthrea...ons+ace+racing

I'll be in the shop all day, give me a call!

g

Gilbert@Ace Racing

In the quoted mount discussion we are told to not use a "solid" tranny mount. for good reason. I agree with this comment.

I do not agree with the use of an Energy Suspension mount. It is simply too stiff. They create allot of NVH and have been known to cause failure of the tailhousing itself at high mph.

Hope that clears it up.

g

Johnny5

iTrader: (2)

Anyone know where I'd get a GM mount? Can I get it from NAPA or something or do you have to get it through a dealer?

A part number or description would be fantastic if you had it.

Gilbert@Ace Racing

That is probably one of the ost common mounts on the market today. It should be very easy to locate at most any neighborhood parts house.

g

MeanWS6

I was in the same situation with ya when I first got my TH400

1. You need a bigger cooler - even then it will still run a little warmer; B&M makes em

2. yea, that converter is WAY to loose as mentioned; I run a 4000 TCT and LOVE it on a 250 shot

3. I hope u when with a TCI flexplate and new mounts; if not thats your gig

4. Baffled

Johnny5

iTrader: (2)

Here's my plan so far:

1. Heat Issues
- I've installed the Autometer trans temp gauge to get some baseline readings.
- I've removed the A/C To make room for a cooler mounted up front for better airflow
- Will install the B&M 28,000 cooler which is almost double/triple the current size cooler that is mounted parallel to the ground in front of the passenger side wheel.

2. New converter ordered from Gilbert at ACE that should be much tighter to handle the shot.

3. The fluid out of the vent tube is probably just an overheating issue. The fluid when checked though is still a bright red and doesn't smell burned at all. It has only done this to me once with since the last fluid change.

4. The vibrations are getting a few things thrown their way. My current setup used all SBC stuff (flexplate, adaptor, SBC converter). This stuff is all getting replaced with LS1 specific stuff.
- TCI SFI flexplate / ARP bolts
- Ditch the converter adaptor since the new one will be LS1 specific for the pilot
- LS1 specific converter
- Will install prothane/energy suspension motor mounts once the trans is pulled and put a rubber mount on the tranny as well instead of the prothane mount there.
I'll then fool around with the pinion angle even more if it still has any signs of shake but I want to know if it is the setup or the pinion. I'll be happy to see the vibration go but I want to know what it was as well.

I will also take the tranny somewhere local to have it checked as the front pump is leaking a bit and it will be pulled anyway for the converter swap.

I hope this plan yields a more reliable, better performing setup with no vibrations.

MeanWS6

on the right track boss; what how tight of a stall did you go with?
good luck!
let us all know!

Johnny5

iTrader: (2)

Took the car out tonight for a half hour ride. It's been raining like hell so tonight was my first chance. After about 30 minutes of driving it was about 220 (190-220 the whole way after a 15 minute warm up)in just normal driving. It is only about 68 degrees outside as well so it looks like it is a bit warm. I have no idea how hot this thing must have been getting racing, burnouts, etc. This was city and some highway so airflow should have been ok.

At least now I can tell exactly how much the new cooler did for me.

382ssz28

iTrader: (24)

That seems hot. I run a 4000 Vig and my temps are 140-160* cruising in 80+ temps in the middle of the day. Get a Snap-On temp gun and hit the pan and the lines to double check your guage when the temps are up. Just a thought.

MeanWS6

220 is a bit warm but thats right on where my setup is. I don't drive on the street much, but when I do thats the temp she seems to get up to.

Johnny5

iTrader: (2)

As a follow-up I put in a new cooler B&M 28k unit, changed the mounting position from dope style to in front of the radiator between the FTRA and radiator and dropped the smaller hard line connections for -6an lines. The temps went from 220 to around 150.

I was also told to run straight Type-F fluid as well by my builder which he said would also play a part in keeping the temp down. 170 was the hottest I saw it get on an hour test ride romping on it.

performabuilt

iTrader: (25)

FIRST I WOULD GET A BIG COOLER MOUNTED INFRONT OF THE RADIATOR IN GOOD AIR FLOW WHERE IT BELONGS