Turbo 250 or 350

[Alan Roehrich]

Robert, the box I described runs in the 427/425 Camaro in A or AA for two years and hundreds of passes. Looks as good when it comes out as it does going in. I freshen it purely out of guilt.

[buzzinhalfdozen]

I've run a Coan 350 for a little over a season now. Although I had to redo a few things in it after 70 runs tore down and everything looks good. Of course I have no real power but do give it some RPM shift @ 9800, near 10.000 at the stripe. So I'd say RPM is not an issue. Good luck with what ever you chose. Joe

[Bill Grubbs]

The only downside to a T350 (besides the rotating mass) is whenever first gear is under power, second gear is turning the incorrect direction (ie in reverse). Therefore when the 1-2 shift is made second gear must stop rotating and reverse direction (to the forward direction). A secondary impact to this is when in first gear over a certian RPM (6XXX +, each one is different) the second gear clutches will start to drag, and when they are rotating in the opposite direction it has a tendancy to kill ET.

With all that being said, the reverse rotation, the stop, and the sudden forward acceleration of second gear could have negative consequences to the durability of a T350 trans it is consistantly over-reved. However most racers I know use 1st gear only to get the car moving and shift to 2nd very early.

It has also been our experience that shifting 1-2 early does not negatively affect ET to the same extend shifting late does.

I hope I got that all right.

[VORTECPRO]

Originally Posted by Bill Grubbs

The only downside to a T350 (besides the rotating mass) is whenever first gear is under power, second gear is turning the incorrect direction (ie in reverse). Therefore when the 1-2 shift is made second gear must stop rotating and reverse direction (to the forward direction). A secondary impact to this is when in first gear over a certian RPM (6XXX +, each one is different) the second gear clutches will start to drag, and when they are rotating in the opposite direction it has a tendancy to kill ET.

With all that being said, the reverse rotation, the stop, and the sudden forward acceleration of second gear could have negative consequences to the durability of a T350 trans it is consistantly over-reved. However most racers I know use 1st gear only to get the car moving and shift to 2nd very early.

It has also been our experience that shifting 1-2 early does not negatively affect ET to the same extend shifting late does.

I hope I got that all right.

Does the metric 200 function different? Any 8 inch converter weights?

[CrateCamaro]

I've had very good luck with 350's for a long time. I have 3 cars with sister transmissions...tci sprag (the $60 one) and a TCI forward manual VB everything else stock. Good coolers as well. RPM has never been an issue. 2 of them get beat up on the street real bad...over 7000 RPM shifts and my crate car sees 7000+ in all gears and at the stripe. My other street car runs 9.60's on nitrous and the trans has been in the car for 8 years with no freshen. That see's 8500 to 9000 rpm (377 sbc) every gear change. Does anyone know if a 350th converter will work in a 200 Metric?

[VORTECPRO]

Originally Posted by CrateCamaro

I've had very good luck with 350's for a long time. I have 3 cars with sister transmissions...tci sprag (the $60 one) and a TCI forward manual VB everything else stock. Good coolers as well. RPM has never been an issue. 2 of them get beat up on the street real bad...over 7000 RPM shifts and my crate car sees 7000+ in all gears and at the stripe. My other street car runs 9.60's on nitrous and the trans has been in the car for 8 years with no freshen. That see's 8500 to 9000 rpm (377 sbc) every gear change. Does anyone know if a 350th converter will work in a 200 Metric?

I believe the converters are different between the 200 and 350 but I think you can set the 200 up to run the turbo converter.

[Alan Roehrich]

Originally Posted by CrateCamaro

I've had very good luck with 350's for a long time. I have 3 cars with sister transmissions...tci sprag (the $60 one) and a TCI forward manual VB everything else stock. Good coolers as well. RPM has never been an issue. 2 of them get beat up on the street real bad...over 7000 RPM shifts and my crate car sees 7000+ in all gears and at the stripe. My other street car runs 9.60's on nitrous and the trans has been in the car for 8 years with no freshen. That see's 8500 to 9000 rpm (377 sbc) every gear change. Does anyone know if a 350th converter will work in a 200 Metric?

A 350 (as well as a 400) uses a different pump drive hub, a different stator shaft spline, and a different input shaft spline from the 200 Metric. Some of the 200 builders modify the pump and forward input drum in the 200 to match the 350. If I were buying a 200, I would certainly want it done that way.

[Mark Yacavone]

Originally Posted by Alan Roehrich

A 350 (as well as a 400) uses a different pump drive hub, a different stator shaft spline, and a different input shaft spline from the 200 Metric. Some of the 200 builders modify the pump and forward input drum in the 200 to match the 350. If I were buying a 200, I would certainly want it done that way.

Let me add: The main difference is total stack up height of the 200/2004R/700R4 converter, which is about .300 shorter than a a 350/400.
The stator shaft spline is actually the same on all of them,..even the 125/440 FWD trans.

Now ,seeing I don't build transmissions for a living ,I'll assume I can post this here.

200 durability issues:

When we built the trans for Tibor's L/SA Firebird (which is now for sale),we decided to go with the 200, already having done the research on my Omega.
I built the first one , using a Turbo Action valve body and a Sonnax billet servo, and no lightened or heavy duty stuff. That trans was in the car all of 2006 when Tibor won enough rounds to tie for first place in the world points.
After that season, I did an inspection and found the factory writing still on the direct clutch frictions. The factory replacement narrow band was still like new also.
I built a second trans for a spare for the 07 All Star race. That unit now has a Leo (REMAC ) 2.91 low gear planetary and a wide Kevlar band ,just for insurance.
All in all ,we've had great dependability with both units. One of them started to roll a low sprag one time, but we caught it in time.
The Firebird is now in the 11.70 range @ 3600 lbs ,and still no problems.

Just some real world experience. No conjecture here. Carry on...

[Alan Roehrich]

Mark, you are indeed correct on the stator spline, I checked my notes, and was going to correct my post, but you beat me to it.

[CrateCamaro]

Originally Posted by Alan Roehrich

A 350 (as well as a 400) uses a different pump drive hub, a different stator shaft spline, and a different input shaft spline from the 200 Metric. Some of the 200 builders modify the pump and forward input drum in the 200 to match the 350. If I were buying a 200, I would certainly want it done that way.

seems like alot of BS to build one of these trans. Probably easier to just buy one. I can imagine alot of machine work to make things fit....not that hard when u have the machines at your finger tips...but when your boss is watching its tough to say your making parts for the tow motor...HAHAHA