T5Z to C4....

[Bradleyrj]

I am thinking about going to an auto in my car. ..

1990 GT, 347, TFS TW Heads, TFS Cam, TFS Track heat, Twin turbo set up using twin Grand national turbos' Front mount, T5Z, 3.73 gears (now but installing 3.27's)

Lets assume even with good shifting...I ran a 10.75...@ 130 ish.. how much could it pick up by going to a C4, 4000 stall, brake...something that will handle the power but be a little easier on the car compared to the T5?

I havent made a pass with this turbo set up yet.. but I would guess 500-550 rwhp is gonna be pretty easy but also the limit since im on the stock block. I want to go as fast as possible but this motor needs to live a few years cause I cant afford a dart block right now.

[91notch]

Should def. pick up with an auto. IMO Go with an AOD instead of a c4, if you are going to still drive it in the street.

[Bradleyrj]

I had thought about that to. Either will be full manual regardless which I choose.

[Bradleyrj]

Anyone interested in trading a built auto for a built T5? (Upgraded from W/C to T5Z spec using Hanlon Parts) New Promotion Powertrain built clutch...

[gearmesh, inc.]

A 4000 stall open converter with 3.27s will suck on the freeway at 60mph due to excessive slippage thru the converter heating up trans fluid pretty good. With your turbo setup having gobs of torque starting right in the midrange, I would shoot for about a 3000 stall with that rear gear and a C-4 so that your freeway cruise rpm will be closer to the stall speed of the converter. A 3000 stall should still be loose enough to let you build most of your available boost on the line to leave hard.

If you pick a good efficient stall converter, you may be able to get away with a 3200-3500 stall. I rode on the interstate with RM1 in his old black coupe with the YSI, 4.11s, and AOD setup with a non-lockup Mr. Cameron 3500 stall converter. Even while cruising in overdrive, I was rather impressed with the efficiency of his converter. Converter flash wasn't too bad at all when tipping slightly into the throttle to ease past slower cars despite cruising RPM in overdrive being around 2400. Knock it down a gear and stab it and that 3500 stall flashed perfectly as designed. The converter didn't let the engine go beyond 3500 until road speed increased enough to require more engine rpm to keep up.

For comparison, I once had a 3000 stall Precision Industries converter in an old ride of mine and that converter felt like a rubber band well after the stall speed was met. Don't get me wrong, PI uses good quality hard parts in their converters, but the brainwork behind which components work well together is questionable to me.

Do yourself a favor when looking for a converter and call Cameron at Torque Converter Services in Columbia @ 803-754-8139.

[Bradleyrj]

Ok.. so your saying stick with the c4 instead of the AOD?

[gearmesh, inc.]

Yeah, I would stick with a C-4 since you plan on running a 3.27 gear. That will save you some money vs. a 600+ horse capable AOD.

As far as long term durability is concerned, the AOD with the right parts will be stronger than a C-4. But, the neat thing about a C-4 is that you usually don't have too much money tied up in one anyway and they are easy to sell to recoup some of your investment if you decide to step up to a built AOD.

If you are lucky enough to ride or drive someone else's ride on the street with a 4000 stall converter, I would recommend doing so just so you know what you might be getting into with that big of a stall on the street. Make a note of what brand converters you may be able to test out, so that you may only have to make a one time investment on your choice of converter. I myself hate spending money more than once to get what I'm looking for.

[Bradleyrj]

My previous car had a 400 stall but it was an all motor 466 with a 3.73 rear.. BIG difference. I guess I need to find me a C4 to start working on.

[gearmesh, inc.]

Another option is to go with an AOD-E which has a 12 volt powered computer controled lockup via a clutch plate in the converter. You can manually control lockup yourself via a user selectable switch. This way you can run any stall converter you want and enjoy bypassing the flash while cruising the highway. One thing to keep in mind is that a stall converter typically has a smaller diameter, so a lockup clutch disc has to shrink in size, too, to be able to fit inside. Be carefull of the amount of power you try to send through a single disc.

If you really want to get sick with it, get a multiplate lockup converter and you will be able to hold WOT power in lockup for a time improvement in your 1/4 mile times. You don't really need torque multiplication in the top half of 3rd gear anyway, so you might as well send all your power to the ground. Too bad these multiplate converters cost $1000+ and they are heavy, too. If you are only concerned with 1/8 mile, don't waste your money on a multiplate.

In contrast, the lockup function in a regular AOD is purely mechanical in nature facillitated by the split shaft power delivery it has. The long skinny shaft goes directly to the lockup damper attached to the front cover of the converter and carries 90% of the power in 3rd, and all the power in OD. In a non-lockup AOD converter, there is no lockup damper and the skinny shaft power comes from the turbine in the converter, which always drives the hollow shaft in either style converter. Of course, for the ultimate in AOD strength, a one piece input shaft is required and it negates the lockup function even in a lockup AOD converter.

Have you been thrown enough curve balls yet?

[Bradleyrj]

Naa keep it coming. Its hard to get anyone to talk ACTUAL auto trans tech. Most people dont understand (im no expert but want to learn) so they dont pay attention.

I have thought about a regular AOD. I have seen valve bodys somewhere that will shift by itself (as stock) but will not shift into OD while under WOT. I dont remember which one it was. The one thing that concerns me with the AOD is TV cable initial setup. I know that if you do not get it close to right very soon on first start up you can mess some things up if the pressure is set to high. BUT thats about all I know about that.

You can pour a few C4's out in the floor disassembled and I can put one together. Only worked on one AOD and one 4R70W ( The first auto I redid myself )

I have looked at a 4R swap as well. Pull from a later model V6, swap valve bodies, put a decent convertor in it and be done. Thoughts...

[gearmesh, inc.]

A 4R70W is about identical to an AOD-E except for having a wide ratio gearset. The 4R70W extension housing takes a slightly larger OD driveshaft yoke, too, but not as big as a C-6/E4OD one. Extension housings are interchangeable between AODs and 4R70Ws if you want to keep your existing fox body driveshaft yoke. Output shaft splines are identical between the two transmissions. The best cores to look for are ones from '94 to '96 F-series trucks. These truck trannies still have the smallblock bellhousing like the V-6 Tbirds, but with more clutch plate capacity throughout.

A Lentech Strip Terminator Valvebody will let you run your regular AOD without the need for a TV cable. It is full manual with fixed line pressure and for 3rd gear it helps out the AODs small 3-4 clutch by also applying the reverse clutch up front. Torque capacity in 3rd gear is equal to the holding power of a Turbo 400 in 3rd. The manual shifts with this valvebody are instant with no delays. You move your shifter, and you imediately feel the shift. It also converts your shift pattern from 1, D, OD to 1, 2, 3. Overdrive is acutated electrically via a user installed rocker switch that you can put anywhere you like. The only drawback to this valvebody is its cost of $645. Lentech has a patent on the extra clutch engagement process in 3rd, so no one else can legally make a valvebody comparable to it. However, if you plan on sending 600-800 horses thru an AOD, this is the valvebody you won't be disappointed with. More horspower than this can be fed through an AOD if you upgrade to their 26 spline 3-4 clutch drive setup (about $700 in parts!). Stock spline count is 23 splines in this area. In my opinion, if you are making enough power to need the 26 spline setup, street driving is not a priority of yours anyway and you will probably be running a glide or lenco by then.


There are a couple of options for the AOD-E/4R70W transmissions to be run without electronics.

- One option is Lentech offers a full manual fixed line pressure vb for these too, but they will not sell a vb by itself with the extra clutch 3rd gear function like the AOD. They will sell you a complete AOD-E/4R70W transmission set up this way, though ($$$$$$). I called them last year and inquired about getting just the vb with the 3rd gear extra clutch function and they said that at that time they didn't want to release it to market for fear of it being copied??? WTF? Maybe they are waiting on getting a separate patent approved for it??? What really sucks is this vb will still run $645 like the better one for the AOD????? I would rate hp capacity to be around 600-650 with this vb.

-Option two is Transgo makes a full manual control shift kit that includes a vacuum modulator to take the place of the factory line pressure solenoid. This way you can have modulated line pressure in proportion to engine load so that it won't hit so hard at light throtle with a tight converter. The vacuum modulator also gives instant line pressure rise, as compared to the delay in rise if you are running factory electronics. If you are running boost, they make a boost bleed-off tee-in valve that you can get separately. Or you can just not run a vacuum line at all and have full line pressure all the time. Not really a big deal with a looser converter, though. Last price I remember seeing for one of these shift kits was around $260. Look around and you may be able to luck up on one cheaper. I would rate hp capacity to be around 600-650 with this shift kit as a viable alternative to the more expensive Lentech one for the AOD-E/4R70W.

As far as WOT operation in OD with any overdrive passenger car/light truck transmission, you are pushing your luck. Passenger car and light truck overdrives are not engineered to take that much power in OD and last, no matter what you do to them. Just use OD for cruising to take the pain out of running some low gears in your rearend. However, if you decide on an E4OD/4R100 or a 4L80E, these trannies can take some abuse in OD, but you will sacrifice some ET with their heavier internals.

[Bradleyrj]

Got a line on a C4.

very fresh w/only 4 passes and 100 easy street miles, PA street/strip vb, Hughes aluminum pan, h servo. Will include spare c5 drums, steels, selective rings, shafts, seals, extra servos, kevlar bands, etc.

This is a small bell, case fill c4. I'll include an adjustable cross member, bell housing, dipstick + tube, trans cooler and block plate as well.

Just what I need for a good starting point. Get it in the car and drive it some. Start modding it later as I start to make more power. The parts it has now should be ok in the 450-500 rwhp range with a good convertor right?

[gearmesh, inc.]

Sounds like you got a pretty complete C-4 setup with spare parts to boot. Those small bellhousing ones are getting hard to find. 450-500hp should be no problem for a stock input shaft and forward drum. If you start getting up to the 550hp+ realm, then consider a hardened input shaft and reinforced forward clutch drum. You may be lucky enough to have some of these parts in the transmission already.

A good way to check for the presence of a hardened input shaft is that most of them have centers drilled on each end, where stock shafts have none.

[Bradleyrj]

A good way to check for the presence of a hardened input shaft is that most of them have centers drilled on each end, where stock shafts have none.

Been down this road before. It will have a hardened shaft installed before I put it in the car. I would LIKE to get a brake and put in it but im going to wait a while. Drive it like this for a while. See how I like the auto. If I don't like it I'll sell it and the T5Z towards a modded TKO-600 or T56.

[Bradleyrj]

Well. Back to the top. I am finally getting around to getting more parts for this swap. I got a JW Wheel the other day. The trans does NOT have a hardened input so I want to get one. Also need a Cheetah shifter for a C4 if anyone knows of one for a decent price.

[WWhittle]

to answer your original question- if you are great at shifting gears, you might only pick up 3-4 tenths with a correctly setup auto. If you suck, i have seen as much as a full second picked up from only an auto swap.

and BTW- where the hell is your build thread? you are working on that thing all the time- we could be following along!!

[Bradleyrj]

to answer your original question- if you are great at shifting gears, you might only pick up 3-4 tenths with a correctly setup auto. If you suck, i have seen as much as a full second picked up from only an auto swap.

and BTW- where the hell is your build thread? you are working on that thing all the time- we could be following along!!

I have never "raced" a 5 speed car. Just done a lot of playing. I am pretty sure I would suck at it...

The build thread...nothing has changed worthy of a seperate thread. I had to take the dash out again and semi redo some wiring, fix the radiator hose, dip stick. Little stuff like that. I HOPE the maiden voyage is this weekend. I am planning on borrowing my buddy's GoPro camera and big ass suction cup to get some video.

I have the base tune I need to get loaded into the TwEECer but until I do I have to stay outta the boost.

[WWhittle]

I have never "raced" a 5 speed car. Just done a lot of playing. I am pretty sure I would suck at it...

The build thread...nothing has changed worthy of a seperate thread. I had to take the dash out again and semi redo some wiring, fix the radiator hose, dip stick. Little stuff like that. I HOPE the maiden voyage is this weekend. I am planning on borrowing my buddy's GoPro camera and big ass suction cup to get some video.

I have the base tune I need to get loaded into the TwEECer but until I do I have to stay outta the boost.


congrats on getting to that point, i am sure you are excited. now it's time to go break some parts!

[Bradleyrj]

congrats on getting to that point, i am sure you are excited. now it's time to go break some parts!

SSSSSHHHHHHHHHH I cant afford to break anything else right now! I have all the parts to rebuild the rear and upgrade when the stocker blows but thats all the extra parts I have right now.