i have a 70 coupe which i just bought. the trans will not shift i believe its starting off in a higher gear. but it works right if i put it on 1 and move it up accordingly. is there a simple fix for this or should i start looking for a replacement or rebuild it. im a first time classic owner so any help will be greatly appreciated. oh also when in D if i punch the gas is dosent really gain speed too fast and sometimes theres a grinding noise

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It could be starting in 3rd, if it seems lethargic (that means slow) but picks up considerably when manually shifted then it most likely is. I would replace the vacuum modulator, make sure the line for it isnt kinked, broken or damaged, and replace the vacuum lines going to it. Modulators are cheap, usually less than $10 so its good insurance. Also you could check or replace the governor, its inside the tailshaft housing and adjust the bands per directions in the FAQ.

the modulator and governor act to gether to tell it when to shift. The bands are part of the shifting process. Alternatively you could have it rebuilt, but if it works fine you really dont need to, just have it adjusted so it works the way you want it to. A good shop can help you with it, but most will try to get you to rebuild it. The reason they want to rebuild it is because if they are going to work on it, they want to know whats going on inside it and they want to be positive it has good parts and a correct build before they start. but if it works good, they can adjust the governor, modulator and bands so it shifts right.

Or bring up here to the great white north and I'll do it for you, burn a T bone on the grill and BS about old cars for a while.

 

ok thanks ill try that...where can i get a good breakdown of these transmissions incase i do have to tear into it?

 

some good info here... http://www.network54.com/Forum/260730/

and I am around here plenty, I can scan pages from my book for you, just not the entire C4 section.. Its freakin HUGE! almost 100 pages.. they arent difficult to do, but you do need to have an idea of what you are doing before you start. Why dont you pick up a rebuilding video? I think Summit has them still, its worth a try.

My tech school instructor for transmissions told me "They are idiot proof, unfortunately they are not moron proof" They go together one way, and its obvious, but a moron will leave parts out that are needed, or try to force things. I dunno, mechanical stuff is just really easy for me.

 

First don't TEAR INO IT

Tearing into it requires education and experience. However I have 2-3 books on the C-4 I can send you. Contact me via e-mail don_albasi@yahoo.com

I will weigh the books and all I need from you is a proper envelope with proper postage for the weight.

From your description it may well be as previously suggested the governor. It could be that the governor is stuck open or it could be that the 2-3 shift valve is stuck open.

Getting to the governor is a matter of dropping the drive shaft then removing the exoension housing. The governor bolts to a counterweight and when unbolted can be removed simply. It comes apart easily but you would need to do it carefully as there are springs and it's eash to loose tract of the parts.

 

im usually pretty good but i never messed with the c4's so i just want a good refrence to go by..thanks for the info. also if a prior year c4 were put in my car could this be why its not shifting like its supposed to. ive been reading and seem to gather that c4 prior to 68 had to be in the second to last position to shift correctly is that right?

 

Oh DGA, its fun to help them once they have it all torn down and pieces everywhere... he is 100% right, dont tear it apart by yourself


What I intended was to learn about it first, they are simple but not always easy. I still have a TH350 that wont go in reverse no matter what I do to it. Built hundreds if not thousands of them, and this one just wont work right. I think its the devil.

Do you know where they could all get reprints of the manuals you have? mine are somewhat expensive and mostly out of print. the latest auto trans manual cost me $120 and its only the overhual section, there is another complete one for the in-car. I dont think they want to spend that kinda dough, but if you have a good manual for the beginner, it could be worth its weight in gold to most of the people on here.

They arent magical, but they are precise and everything needs to be BEYOND clean.. so a friend who is OCD and cleans everything would be a huge help. I still think that almost anyone can rebuild a C4 with a bit of help and guidance. Of course, I put alot of faith in humanity that most dont..



ps. Struts suck.

 

Not following...

 

i just went drove it again and it seems that when i go from 1 to 2 to D it seems like its slipping some in 2 and a lot in D so could that just be adjustment problems?

 

Do a search on ebay on C4 there is someone selling c4s rebuilt for 500. 100% feedback and a lot of postive posts - that's the route I would go.