Improving the C4 automatic

mudstud · Mar 15, 2013

I am going to rebuild my C4. I will be installing an AA shorty kit. I will have to install a full manual valve-body because of the shorty kit. What other upgrades would you do besides the ones mentioned in the tech article? http://classicbroncos.com/tech/improving-the-c4-automatic The rig will see some street but mostly trails. Modified 351 (not heavily), i-blackbox, Dana 20 HD output, 4.88 gears, and 39.5 Iroks.

blubuckaroo · Mar 15, 2013

That's a good tech article. Sounds like my last rebuild. The one real weakness of the C4 is the 2.46 first gear ratio. It's just too darned high and will make even the best motor feel poopy off the line. I'd install a 2.92 low ratio gearset to improve both the 1st and second gear performance. Since your's is mainly used off-road, it would really help. http://www.atiracing.com/products/gears/lowgears.htm

broncosbybart · Mar 15, 2013

Meh, while I think the stock gearing isn't ideal, I haven't coined up for the gear kit. Your doubler will be plenty for gearing anyway.

The C4 is a really good trans. There isn't much you'll need to do to it. I'd recommend going through the pump and getting new gears, if available. Get a rebuilt torque converter, too. I don't know what you are doing for cooling, but I'd run an auxiliary cooler for sure.

On the trans I just built, I did the #9 thrust washer oiling mod and drilled the corresponding oil cooler port. Everything else was kept stock. On the board are several threads for rebuild parts. Most kits don't include everything. You can tear it apart and check the bushings to see if they need replacing before ordering. I'd recommend getting the shim kit, sprag, a new servo for the reverse band, and a deeper sump pan/pickup (optional) but nice, along with a trans temp gauge. This is in addition to the standard stuff you'll need.

I don't think you'll need any high performance parts, but if you want to get a kit like that, check this out. It also comes with some of the parts not included in a typical rebuild kit. You'll also notice how relatively few major parts are in it, as they're really not needed.

http://www.broaderperformance.com/ford-c4/28-c4-500-horsepower-rebuild-kit.html

Oh, and if the valve body you have has an adjustable line pressure feature, I would recommend checking and setting it so that the pump isn't working full bore all the time.

GStaudt · Mar 15, 2013

I didn't look at every link that was posted ahead of me, so pardon me if this has been said already. You can purchase a kit to adjust shift points and provide a sportier feel, if that's what you're looking for. I read that there are a variety to choose from but hands down, Transgo makes the best one. All the parts, none of the problems. Direct fit, and can be done with hand tools in no time at all.
http://transgoonline.com/products.php?cat=C4,-C5&homeinclude=catalog&category_id=70&parent_id=70

They make other products too for the C4 so might be worth a look if you're interested.

airbur · Mar 15, 2013

Viper needs to reply here. He built me a bullet proof Bronco C4 with a bunch of upgrades to survive behind the injected 427W I built. He has a laundry list of stuff he did to improve it. I'll see if I can't find it.

Viperwolf1 · Mar 15, 2013

GStaudt said:
I didn't look at every link that was posted ahead of me, so pardon me if this has been said already. You can purchase a kit to adjust shift points and provide a sportier feel, if that's what you're looking for. I read that there are a variety to choose from but hands down, Transgo makes the best one. All the parts, none of the problems. Direct fit, and can be done with hand tools in no time at all.
http://transgoonline.com/products.php?cat=C4,-C5&homeinclude=catalog&category_id=70&parent_id=70

They make other products too for the C4 so might be worth a look if you're interested.

Transgo makes good stuff but its useless with a full manual valvebody. There are no automatic shifts.

The Broaderperf kit is a good one but it might be overkill with a mild 351W. Between that and the tricks in the tech article it should work well for a long time.

mudstud · Mar 16, 2013

Thanks for the comments. I am looking forward to getting this thing on the trail.

lilthom · Jul 16, 2013

Viperwolf1 said:
Transgo makes good stuff but its useless with a full manual valvebody. There are no automatic shifts.

The Broaderperf kit is a good one but it might be overkill with a mild 351W. Between that and the tricks in the tech article it should work well for a long time.

Viper, I'm getting ready to put an Atlas 4.3 behind my C4. I ordered it for the full manual valve body. I have never touched more than the dipstick and pan of a tranny. What's that "Broaderperf kit" you speak of. I am strictly off road only.
Thanks,

airbur · Jul 16, 2013

http://www.broaderperformance.com/32-ford-c4?ps_full_site=1

Viperwolf1 · Jul 16, 2013

More specifically this: http://www.broaderperformance.com/ford-c4/28-c4-500-horsepower-rebuild-kit.html?ps_full_site=1

The best features of this kit are the direct clutch upgrade and the planet mods. The front planet on the C4 takes a beating and you should always check out used ones carefully for wear.

lilthom · Jul 17, 2013

The best features of this kit are the direct clutch upgrade and the planet mods. The front planet on the C4 takes a beating and you should always check out used ones carefully for wear.[/QUOTE]

Thank you, sir.

broncoman1972 · Jul 17, 2013

I notice that Broader has a C4 reverse manual valve body with engine braking in 1st that looks like a modified OEM valve body compared to Art Carrs machined VB. It is cheaper than the offering from WildHorses. Does anyone know how well a modified VB would hold up versus the Art Carr?? It also sems to ba adjustable for different applications which may be a plus. I haven't found any info on the Art Carr that would indicate adjustability.

mudstud · Feb 6, 2015

I have my C4 apart. What do you guys use for a drum clutch compression tool? I had a guy tell me he uses a couple of sockets and a vice. I know that will work but the video I saw had a $40 tool that was pretty slick.

TwoDalesDad · Feb 6, 2015

I have junked a couple of C4 trannies. At least in my case The Skinny pedal may have been to blame, and maybe Suds...The Experts would say the Over-size tires also. once I added a big cooler,and a deep pan .the C4 was ok ..By then I was chicken to stab the throttle much..

Viperwolf1 · Feb 6, 2015

mudstud said:
I have my C4 apart. What do you guys use for a drum clutch compression tool? I had a guy tell me he uses a couple of sockets and a vice. I know that will work but the video I saw had a $40 tool that was pretty slick.

I made one from a big piece of PVC pipe, some big washers and some all thread. Cut some holes in the pipe to get to the snap ring.

BwoncoHowie · Feb 7, 2015

mudstud said:
I have my C4 apart. What do you guys use for a drum clutch compression tool? I had a guy tell me he uses a couple of sockets and a vice. I know that will work but the video I saw had a $40 tool that was pretty slick.

http://www.ebay.com/itm/Tool-Snapre...ols&hash=item43a7f8a5aa&vxp=mtr#ht_1580wt_867

My tool of choice but then I bought it in 1980 so it cost a lot less.

lowbush · Feb 7, 2015

Viperwolf1 said:
I made one from a big piece of PVC pipe, some big washers and some all thread. Cut some holes in the pipe to get to the snap ring.

as well, in a pinch you can use two large C clamps. One on each side, its slow and its a pain because you have to tighten one a little then the other and the same when you loosen but it works if you are only doing one tranny. If you shop it you can find that universal tool for $25 buck on ebay sometimes.

74strokerbronco · Feb 7, 2015

I would add the rollerized #9 thrust bearing kit from broader to the parts list, I thought it was part of his 500hp kit but didn't see it listed. if you use the bearing kit you can delete the drilling into the cooler return passage mod for the standard #9 thrust bushing but still want to mod the pump and ream the return passage itself. the roller thrust is much much hardier then the standard pos thrust bushing.

mavereq · Feb 7, 2015

I used the #9 roller bearing and still reamed out the rear passage.

mudstud · Feb 8, 2015

Found one http://shop.ktcautotools.com/products/automatic-transmission-clutch-spring-compressor-removing-installing

Improving the C4 automatic

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