Hi all, it's been a while but here I'm again still struggling with my drag car.

I'm now working on the car while my engine enters the final steps before assembly and although I know nothing about automatic transmission I wan't to give a good thought to them.

I have both transmission ready available, thus beeing a TF906 and the other one a ZF 4 on the floor. Both transmission will need to be rricked out to make them Drag material, so now is the time for me to decide wich one.

I alreay know what's have to be done to the ZF to make it track worthy, but when thinking about the 904 is when I get lost. I've been trying to trainned myself reading about it, but I always got lost.

What I do have in hand is a standard A904 complete with the converter.

Can you help me with the parts that I shall purchase to make the 904 race ready? What kind of information do you need from me to help me on this?

I don't have engine numbers, but I can tell you the parts we are puting together and the goals we arw aiming ... maybe that helps.

Regards, Martin

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

OK. So here is the information on my engine.

The block has been sleeved and machined to 90mm (we are still good to go to 91,5mm but we prefer to step back to 90mm). Line honed, decked and all the oil passaged has been checked and cleaned.

Steel crankshaft with the stroke reduced to 100mm, the crank has been ligthened in the inner circles (I don't know how to say this, but imagine the crank rotating looking at it from the back, all the counterweigths draws circles, whe have taken the weigth out of the inner circles, like from the "inside" of the crank, thus given the crank more inertia), the rod journal has been reduced to 2" at the same time reducing the stroke to get a safer high RPM.

The Rods are forged, with a cventer-to-center distance of 192mm, pretty wild long rods!

Forged pistons with 1mm, 1,2mm and 2,8mm rings, full floating.

The head has been fully preped with 45mm/40mm Int/Exh valves, 8mm stems, bronze valve guides. Race valve seats, you get the picture.

We are going for 11:1 CR, static CR.

For induction we will run on one IDA-48 carb over an Offy intake and adapter to start and latter we will move to a 3-IDA-48 setup on a fabricated intake.

We are hopfully aiming at 300HP on the flywhell, with a shiftpoint at 6200RPM, safely.


So with all tins in mind, what do you think I shall do to an A904??

Thanks! Martin

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

The TF 904 is a good design and can easily handle 300HP
All I do is rebuild with a TransGo shift kit and up-grade to the wider HD 2nd gear band.
The band apply lever ratio should also be reviewed and changed, if it's ratio is lower then 3.2 (stamped onto the lever)
I would not use a 5.0 lever because I have seen too many of those break.
DD

Hello martin, I would love to see some pictures of that crankshaft!


Greg

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http://www.youtube.com/hyperpack

= 7.560 c / c so I am betting that the pistons are pretty short and light weight.
DD

Hi, thanks Doug for you answer on the 904. So no need to change the valve body? Or any other internal part, only with a service kit with stronger discs and bands ... that sound pretty straight forward to me!

Now how about a reverse valve body or a transbrake? Will the transbrake make any difference on a 300hp car ... the total weight will be around 1400kg.

About my car and engine I promise to start a separate post on thw building with pictures. About the crank I think I do have some pics of the process and finished and about the pistons they are lightweight but they are not too short we kept a long skirt because of the long stroke, of course is shorter that the STD piston skirt, but I have seen Wiseco Pistons for the slant and the skirt is a little bit longer than those, the weight is very similar if not the same as Wiseco Por Tru sets ... ok I promise another post with pics to diacuss about my engine build ...

Thanks, Martin

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

Martin, We have missed you on this site for too long. You convinced me long ago that slant 6 technology in Argentina exceeds anything we have dreamed up here. I like the sound of your project it should be good for at least 300HP with the three Webers. Do you have any flow numbers on your cylinder head? Preferably converted to CFM @ 28" of water.

I have never built a 904, always paid someone else to do it. I don't know about down there but here you want to avoid the 3 clutch drum, some use 4 and some use 5 clutches. I had a trans brake on my car but others foot brake and seem to do just as well. Are you going to be doing drag racing or something else?

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If you didn't drive it there, it's not a street car.

Hi Exner! Its good to be back!!!

I don't have flow numbers yet since the head is still work i progress, but I will get them and post them here.

Abuto the 904 so far I'm thinking of a rebuild kit with Alto Red Clutches, 4 or 5 don't know yet ... the Transgo shift kit ... a reverse manual valve body ... not sure about the transbrake either ... and still have no clue about the torque converter, shifter and all the extra acceaories that i'll need to put the transmission in the car fully running. This will be a do it myself proyect ... never played with automatic but not afraid to ...!!!!

The car will be a single purpouse drag car. I don't meant to drive it on the street ... although with the three Webers and the automatic I'm very tempted .. lol!!!

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

The torque converter is the most important part. Don't try to save money there, get what they call an 8" converter preferably from someone who has experience with lower power cars. Give them your specs and they will try to tailor a converter for your application. If it isn't quite right it doesn't cost too much to have it cut open and recalibrated. You didn't say what cam you are using but if it has around 260 degrees duration at .050" lift you want the stall speed to be about 4200. You may never see that number against a foot brake but it will still work the same.

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If you didn't drive it there, it's not a street car.

About the stall speed do you think that I must put into the equation the type of track that the car will be racing on? Because down here we do not get VHT on the surface at all, as a matter of fact the tracks down here are almost the same as the street pavement ... only one track has the first 50meter of concrete .... all the other are plain pavement ... and the grip is very poor ... so most of the racers can not launch at very high RPM ... because if they do so they will loose grip for too long on the track.

Considering this, do you think that a torque converte with a stall of aroun 4200 migth be too much?? Also as mandatory I must race on radial street tires ... and I mean something luke BFG Radial T/A or similar we can not even use the drag radial tires.
What do you think???

Regarding my cam ... we have gone with a different path here ... with a high lift rather than a larger duration ... but this cam is for the aingle IDA48 ... once we mkve to the triple setup we must grind another one... that will be with a larger duration rather than a larger lift.
I will get the cams numbers for you later.
Thanks for you help here!!

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

Sorry for the misspellings on my posts... I'm writing on my phone here and my fingers hit more than one key from time to time!

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

The quality of the track and the tire limitations are important. There is no use in applying more power than the tires can use. I'd still consider an 8" converter because they always seem to work so well and don't cost that much more but you would probably want to tighten it up to stall at 3000 or so and not necessarily bring it up to that on the starting line. I think I would prefer foot braking to a transbrake where the traction is limited. Before you order anything you need to send a pm to madmax/6 and ask him what he would do in your circumstances, he has the best leaving foot brake car and always has lots of good ideas.

Cam duration has a big effect on low end power so you need to coordinate it with the starting technique you intend to use. Since everybody has to run on the same track it will still be fun.

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If you didn't drive it there, it's not a street car.

Hi Exner,

Thanks a lot for your recomendations. I'll write down a message to Madmax as you pointed out. I thinks I know what I have to do, but now I need to reduce everything to the parts that I need to purchase.

thanks! Martin

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

Hi all, back on the TF6 rebuild. I have been changing e-mail with Pat at SMR Transmissions from Canada I think (I have seen some people here running on their converter with good results...) and their suggestion for my 904 is as follows:

1. SM2244RM - COMPETITION ELIMINATOR Rev. manual VALVEBODY - $285.00
PLUS Valvebody Core charge 25.00
See details at http://smrtrans.tripod.com/smrtransmiss ... /id22.html
2. SM125PS - PRO SPORTSMAN REBUILD KIT 246.95
See details at http://smrtrans.tripod.com/smrtransmiss ... /id10.html
3. SM22916BS-42 - BILLET STEEL 4.2:1 INT. BAND APPLY LEVER 34.50
4. SM53999RK - KEVLAR LINED H.D. LOW/REVERSE BAND 36.31
5. SM12954 - 4 PINION STEEL CARRIER FRONT PLANETARY SET 59.74
6. SM12560B - 4 CLUTCH DIRECT (FRONT) DRUM and PISTON 43.00
7. SM128216 - BILLET HIGH GEAR RETURN SPRING KIT 117.00
OPTIONAL: FOR TOTAL SAFETY FROM EXPLOSION - BILLET STEEL DIRECT DRUM 584.50
(NOTE: If you utilize the billet drum, you will not need item 6 above)
ITEMS LISTED IN 3-7 above can be seen at http://smrtrans.tripod.com/smrtransmiss ... /id20.html
8. SM-904-TF4 - 9.5" PRO SPORTSMAN "RaceTuff" TORQUE CONVERTER 955.00
FOR DETAILS ON THIS WORLD CLASS CONVERTER, see http://smrtrans.tripod.com/smrtransmiss ... /id37.html


What do you think about this???

My thougths about rebuilding my trans were tu put together a rebuild kit with Red Discs, KEvlar bands, TRansgo TF3 full manual kit, a 4,3 lever, deep pan and a 8" Converter with the stall around 4000 ... as I understood this was OK for a Drag race baseline rebuild ... and later move to a transbrake Valve body ....

Can I have your two cens on this???

Maybe you can refer me to another TRansmission Shops?

Regards, Martin

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

My 904 handles about 500HP. Use good clutches, bands, and steels. I also used a V8 drum to hold 5 clutches rather than the std. 3. I have a manual forward shift VB. Don't use the 5.0 lever as Doug said.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc