It seems alot of people dont understand how the C4 works. I build alot of C4s and have covered about every angle of the inner workings of the box. If your trans is bad worn and or been neglected, (not changing fluid) I would not reccomend the shift kit or any adjustment. If you have taken care of it and it shifts ok then put in the shift kit. Its true all shift kits are not created equal. And you usually get what you pay for. I have used all the major brand kits due to customer demand (i use the kit they supplied) I have had no complaints with any,other than the instructions. B&M probaly has the most detailed instructions where Transgo has the most undatiled. (trans go says on the box professional use only) If you get one of the higher priced kits it will usually come with the correct modulator, which has a green stripe. The shift kit will raise the shift points some what due to increased line pressure. But the govoner has the final sayso in the shift points.The flair between 2-3 is caused from the front servo you can also upgrade this without trans disassembly.The reason for your quick upshift is from the 380 gears. The govoner is set up for stock gearing. the govoner is still shifting the trans at the same drive shaft speed but the car is not going as fast due to the gearing. Some kits will send springs with the kit to do the gov. mods. If you pull the modulator dont lose the pin that will probaly fall out. Also use good type fluid (not parts store name) Trick shift has always worked good for me. Although im sure you will get all kinds of reccomendations for fluid type, At least use good name type F. Hope this helps. If you run into trouble ill be glad to answer any other questions Just pm me
Blown What brands/model #s have you had the best luck with? What have customers been most pleased with over the long run? I don't have a problem with going a little more expensive, just want to do it right the first time. Keep in mind, I don't know much about auto trans so I will need fairly detailed instructions.
My '72 has the 250 6 cylinder out of my '74 in it. The transmission I put in the '72 has a shift kit in it of some sort, and let me tell you, the diffrence in the way the car accelerates compared to the way the '74 accelerated with the exact same engine is like night and day. The only thing diffrent in the drivetrain from the '74 is that transmission with the shift kit. Even with a 6 cylinder, it makes a huge diffrence. It can break the rear tires loose in first gear and will chirp them going into 2nd and sit you back in the seat, and we're talking about a 200,000 mile 6 cylinder here. The '74 with the worn out stock transmission couldn't have ever dreamed of doing that. Scott, I too had transmission phobia. I had to pull this transmission apart and take the valve body out to change the shift arm on the side. I now wouldn't hesitate to do anything to my transmission on my own. It's alot simpler in there then I thought it would be. I think you would be extreamly impressed with the way a shift kit makes the car perform.
I would either go with the B&M or the transgo, If you get the B&M get the Transpak. If you go with the transgo get the reprogram kit. Either of these are good kits, but like i said the transgo is not quite as deatailed as the B&M. Just take your time and rember to be EXTRA CLEAN.
Jamie, part of the extra get up and go is vehicle weight. Your 72 should be a fair amount lighter. I have the cheap B&M in mine, and while I had some 2-3 flare before, it is now more pronounced. Can I switch to a Trans Go? Has anyone done this?
I've used both the B&M and the transgo kits with similar results, both kits seem to work fine. I would suggest that you save some money and visit this website, http://www.burly4x4.com/c4/c4buildup/ these mods will save you some money and you will get the same results as a shift kit. I've only tried there valve body mod., never tried there servo mod. Blown 5.0 makes a good point when he says that increasing line pressure and making the changes to the valvebody will go ahead and finish off a worn out tranny.
I have 3.80's with the B&M Transpak.....did the rebuild myself....get rubber every gear, and no problems....................yet. ray
Does anyone consider my tranny to be "worn"? It has 58,000 miles, driven the first 55k (literally) by a little old lady from Pasadena (Texas) over 20 years, to and from church and groceries. It spent the last 8-10 years in a garage without any driving. It feels like it runs brand-new, and has no problems, other than a rotted out seal at the shift linkage that lets fluid leak a little (I have the new seal and o-ring to put in when I do the shift-kit). The 1500 shift I talk about is what is was supposed to do stock and worked fine with the 2.79 rearend, but with a 3.80, it just goes through the gears too fast in D. I originally thought I would have someone else rebuild it to "500HP" specs, and add the shift kit then, but I don't have the $$$ and won't for a while for that kind of job...maybe a year or so. Would street driving with the kit kill my trans between now and then? My local track is closed down so it is just fast take-offs from county road stop signs and small-town city driving for a while.
No it won't kill your tranny. The shift kit will help hold the shift to a higher rpm and will shift harder....plus you can mess with the mod. to tweek it to yer liking. The 3.80 gears will make the car shift from 1st to 2nd very quickly....so that you should expect. I know I was suprised in the difference. ray
If the fluid is and stays clean you probaly wont have any problems, That is not excessive milage but it is excessive time. The seal that is rotted is made of the same stuff that the clutch pistion seal is made of. If you do the mod. and it holds then you know you will be allrite, if it dont the trans needed rebuilt anyway, all you will lose is the fluid. A rebuild wont cost that much unless you go to replacing hard parts. A stock internal C4 will take a lot of punishment with nothing more than good clutches and tight clearnces. I have seen C4s stock take over 500 HP. You will need to tune the Govoner to get the shift points where you want them.
If I'm correct, I think the C-4 was spec'd out to handle up to 500HP. IMO C-4's get no respect. Everyone thinks you have to have a 9 inch if you have a little horse power....not true. 9 inch is definately the way to go if you can. They are easy to work with and come with the posi and all.....but the 8 inch is respectible fer sure. ray
Putting in a shift kit is a good way to get to know your C-4. After that, you'll be confident enough to do a full rebuild if you ever need to.
I've never heard of a stock C4 that was designed to handle 500 hp. It's kinda like throwing a 500 shot of nitrous on a stock 302, it might take it the first or second time, but it won't last long.
I don't have, and probably never will have, 500 HP...I just want my tranny to be able to handle that, so it is safe it I ever reach 300, or even 400 HP.
