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So I have a C6 I'm rebuilding this weekend, I got a kit with the band, filter, clutches, modulator, and all seals. The trans came from best I can tell is an '83 small block van.
Are there any tips or tricks of the trade with these transmissions? I would like it to shift a bit firmer especially when at WOT, but I still want it to be comfortable. I'm open to getting a shift kit but I heard there was something I could do to firm up the shifts without one.
Automatic transmissions are complex and take a few special tools. I would google it if you need any advice, not many people on here take on rebuilding a automatic tranny.
Basically, if you see worn metal, replace it. The kit you buy is often a one-part-fits-all kit. It will include extra o-rings and gaskets that you may not need. This is because the parts will fit different servo housings, different tail housings (2wd vs 4wd) and different clutch configurations (some had more plates/frictions).
Install a shift kit if you can afford it. This will help with the shift points and help lubricate better (prevent premature wear). This will require taking apart the valve body and lots of time spent carefully scraping off gasket material between the valve body halves.
Even more expensive is replacing the thrust "bearings" (brass washers) with needle bearings which will reduce friction between the rotating parts and free up extra power.
I installed an extra steel/friction in one of the clutch packs by replacing the flex plate with a notched one (this part is available at your local transmission shop). It was an optional part in some C6 transmissions and a popular replacement. Basically it gives more holding power. The steel/friction was already in the kit because some transmissions already had them installed.
Another common upgrade to handle more power is replacing the 4 gear planetaries with 6 gear planetaries.
You can replace the band lever and servo cover/plunger for harder shifts. I think the consensus on the best combination is R servo and H lever. Any more than that and you risk damage to the transmission. Here is a webpage that talks about it: Lets talk about C6 Servos and Levers
Ok, I guess there was one part that required a special tool. This is the direct drum spring pack that had to be removed to replace the o-rings underneath it. I took it to my local transmission shop and they compressed the spring pack back into place for free.
The image below was invaluable for parts identification and assembly order for me.
Well having done lots of C6 trans over the years I can give you some pointers. You will either need to buy or make a low reverse sprag spring compressor. You will want to make sure everything is incredibly clean and then re clean everything while assembling. Use blue assembly goo, make sure all your clutches soak for a minimum of 4 hours in clean type f (mercon if using alto red or similar). You will also want to add some required updates, the boost valve and springs in the superior kit are a must! It addresses the major issues.SUPERIOR KIT WITH BOOST VALVE and Transgo Spring Kit use both of these kits to correct the weak and broken springs in the valve body. The superior kit has the major updates for oiling mods. Find the blue assembly goo here
also I have attached the actual ATSG manual for the C6. DO NOT USE the Haynes rebuild guide, it is wrong and will get you stuck. I highly suggest you take tons of pictures in order during disassembly and keep everything organized. Also do not use any type of lye based cleaner like purple power. Use simple green purple which is available at home depot as its aluminum safe. Yes I just realized how old this thread is.........
....make sure all your clutches soak for a minimum of 4 hours in clean type f (mercon if using alto red or similar)......
Why would you use type F fluid? Are you drag racing? I don’t believe the C6 ever used this fluid. The dipstick on my ‘87 called for type H which was replaced by Mercon and then Mercon V as the recommended fluid.
When I had my trans rebuilt several years ago, I used the wide ratio Motorsports kit which used the 6 pinion planetary assembly from the 4R100.
The C6 was specified to run type F up until 1978, most rebuilders still require a low friction modified fluid in the C6 and that is what Type F is. You only want to use Mercon if you are running non stock clutch discs like kevlar infused such as alto red eagle. Also Mercon V should never be used in a C6, there was a tsb from ford that allowed mercon apps to use mercon v however the C6 uses different materials and was phased out by 1988 in everything but DSO.
