460 Ford Forum banner

Drag race transmission. C4 or TH400??

18K views 28 replies 17 participants last post by  Duane 
#1 ·
3300# Torino, 472" with a little NOS and currently a C6. The C6 is not working for me, so I need to switch to a unit that will work.
I like the idea of a full built C4 because of the light weight of the unit as a whole, and the light weight rotating internals. But I hear too many negative comments about them in full race applications....and mostly from Ford guys!!

I also am considering a GM TH400 with a BBF bellhousing. I know this trans will take anything I can dish out, and if I have trouble with it at a race, there are usually several vendors on site that can rebuild, or repair it within minuites.

In any case, this will be a full rollerized, reverse manual unit with a transbrake.
What say you??
 
#2 ·
Talk to Frank Merkl about your C6, thats what i would do first.

The C4 will handle alot of power but it's high maintainance.

I have a turbo 400 built by Mike Ridings and converter also built by him(his on this site), No problems on the street so far, will be at the track later this year!!

Hope this helps.
 
#3 ·
What kind of problems are you having with your c6? If you want to stick with a 3 speed, you have the one to handle the most power with the fewest mods. What is your c6 built like now? To change to any other trany means lots of coin! Scott
 
#4 ·
It has a Frank Merkle reverse manual transbrake valvebody in it. When idling or cruising around the pits in 1st gear, it automatically applies reverse and the transmission goes into a "bind" and locks up the wheels.
I suspect some kind of internal leaking somewhere thats putting the pressurized fluid into the passages that apply reverse.

I pulled the valvebody out and thoroughly cleaned it and inspected it, but could see nothing wrong with it to the naked eye.
I placed a strait edge on both half's and they were both flat as can be.
I re-installed it, and torqued it in the correct pattern. Now I have to rev up the engine to get the car to move in any direction.

Im going to have to spend the coin for another different transmission, as I have already spent way too much on this one, only to have problem after problem.

I've had this unit gone thru several times (4 to be exact) at the cost of $650 each time, so theres no way Im doing it again.
 
#7 ·
When I pulled the pan, it was full of thick black/grey gunk....probably clutch material. That is why I had to clean out the valvebody too.

I've done several C4's myself for mild performance apps., but I did'nt have the time to do my C6 because of work schedules.
 
#12 ·
trans talk

Hello Style2, I'm doing my first ford build and my first delimma was the trans problems that I herd about with the fords (being a chevy guy for ever) so I was going to do mine with a t-400 as well, but I was helping a guy at the track tune his Montego when he told me he was going to put a P/G in his car so as a racer for a long time I said why whenever you have a really good C-6 and his reply was that all the dragster guys are running P/G's my reply was they are 1800 lbs and you are 3600, anyway he done the swap and his car ran the same ET's to the number so I baught his C-6 w/brake and converter and it works perfact as good as any T-400 or P/G I ever owned so take it out and give it to someone that knows C-6 trannys first and don't give up! I would give you the name and number to the tranny guy but we live in sunny south Florida :D good luck friend and happy racing, Butterbean
 
#13 ·
c6

Talk to Frank, I would stay with the c6 and take it to someone who knows what there doing. Way cheaper to build c6. You could go c4 but its not cheap. I run a a c4 with all PA internals and trans brake love the trans 410w with 250 shoot running 9's in a 3200lb mustang, but I have with converter around $2500 into. C4 will work but it'll cost you. Make sure you flush the lines and cooler. Joe
 
#14 ·
Is a C6 cheaper than a TH400??....all the Chevy boys say no, but I have not done comparison shopping yet.
A TH400 has slightly lighter internal parts, right?? Plus it will take the big torque that a C4 wont, correct??

Im kinda leaning towards the TH400.
 
#21 ·
That's because they are under the misguided conception that Chebbies are cheaper, take a look at the rebuild kits the TH400 is about double, and the TH400 is notorious for having BAD core shift and cracking the cases around the fluid passages towards the back of the case. Of course you can buy an aftermarket case but then more $$$$. The C6 can be made to work just follow Franks instructions on clearances when using his valvebody.
 
#16 ·
Thanks for all the replies!! And just for the record, I am not bashing the valvebody from Frank Merkle as it has worked quite well.
Im going to do some research and check out different pros and cons of each trans. and go from there.
 
#17 ·
From experience......my c4 would last 20 passes or so behind my 508. Top of the line parts and converter. Car is pretty light too. If you must have 3 gears, put a 400 in it. Fact is most people here don't have the knowledge that Merkle has. His C6 works but you'll be money and more importantly track-time ahead with a glide.
 
#20 ·
I just switched from a C6 to a glide this spring. My C6 was in my 3,600lb 70Cobra that ran 10.30s for 2 years. Never touched it. Did always flare on the 1-2 shift though. Then went in my Maverick with a freshen, a Merkyl VB, and Sonnax R servo and the recommended E lever. Ran 3 seasons of 9 second passes with no problems. Shifted nice and firm 1-2 and 2-3. Went to the glide for HP and weight savings, but the Maverick is only 2,500lbs. Your car is much heavier. What are you going to gain from a TH400 over a C6? Strength? No. Weight? Not really. A properly built C6 is Just as strong as any TH400. Just build the C6 with he proper parts and you'll be fine. No shifter changing, bellhousings, flexplates, converters, driveshafts...... On and on.... :)
 
#22 ·
Damn, you guys are twisting my arm!! :)
Is there a website or forum that will guide me step by step on how to build the C6 for race duty??
I would like to get the lightweight billet drum this next time around (I think it holds more clutches and steels), and have it fully rollerized, etc.
 
#26 ·
I know your car we have met at Irwindale and I have to ask you who has been doing your trans. I have found it difficult to find a builder that wants to do the c6. They all want to see you a GM trans. The last two rebuilds got me about 100 passes. PM me with the trans builder so I dont use him. I have my trans out now because of a 2/3 flair and am thinking of rebuilding it myself too.
 
#23 ·
Look in the general tech section I made Gregaust and Frank's build up threads stickies. You can have the machine work done yourself and rollerize your own or Jay at Broader can sell you everything already done. One thing I learned that is key, is to follow the directions for clutch pack clearances by whose valvebody you use!!!

I built my trans to Frank's specs and used a TB valvebody from him last year and it worked great. I did lose the front pump gears in mine to some mystery aluminum shavings but everything else was perfect when I pulled it down.

(I had a borrowed valvebody in it) and not sure if the aluminum was already in the valvebody and came loose from a blown sprag previously my converter guy said the sprag in my converter was still perfect.

Hope this don't sound discouraging because like I said everything else is perfect in my trans (I should have pulled the VB apart and cleaned it out as a precaution) matter of fact the only thing being changed is the front pump and it's going back together as it was.
 
#24 ·
I'm gonna twist your arm a little harder. Like has already been said,if you are having that much trouble from your c6,something is bad messed up inside it. As far as t C4 goes w/big power,you will be sorry.thats all I will say on that subject. I have a glide in my car and it works fine,but wmy ole Mav had the C6 in it for 7 yearsw/o rebuild. Toughest tranny there is imo.
 
#25 ·
I love my C6, I built it with all the goodies but I run a transgo modified stock valve body. It handles my 521 without issue but I'm Gona rip it out after only 400 miles to swap to a 2004R GM trans for the overdrive and lockup. I'm looking at $2300 maybe to do the swap, trans will handle 600-650fwhp.

I don't race as much anymore and the C6 with a 3000 stall and no lockup is killing my ability to drive and enjoy the car. C6 has the largest R servos, e lever, aftermarket 5 clutch drums, red alto clutches, wider red alto band and a aluminum deep pan, modified pump and a bunch of upgraded internals from broader performance. Converter is a 3000 stall 10" unit with moly hub and nitrous anti ballooning plate. If your interested...
 
#27 ·
Idk why u don't just rebuild it yourself. The C6 is the easiest trans I've ever built thus far. It's pretty darn simple if u got a manual and some tools. Just takes a weekend or so if u got the parts and take lots of extra time and breaks :)

Do it yourself and save the money. If u mess up u can always take it to a builder. Plus if u build it yourself you know what u put into it and u know its all up to spec.
 
#28 ·
If your going to race $hit is going to brake... But you should be able to get a couple season out of trans... Buy a manual and ask some of the builder on the site ... when I first built mine I took its apart and back together many time learning how to assemble it and pick up some tricks... Imo you can do your trans if you have the time racing can get $$$$$ if you don't do your own work... Main thing is have fun with your hobby
 
#29 ·
I've built my own C4, C6's for years... I only had C6 problems going to the TCI VB, it would burn up the 3rd gear clutches. When I just had the reverse manual in it, it lasted YEARS between problems. Do you really need a brake? I switched to a glide since then.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top