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1986 700r4. I ordered a new input drum, got it in, and the large "teeth" look proper length and fit into my new beast sunshell perfect, but there's 2 variances where that singular cutout between 2 teeth is wide and deep the small cutout is more shallow in the new one.
As tempted as I am to go ahead with it, I'm just wanting to confirm this is not proper. I ordered one for an 86, the box says 93 and up and the part number doesn't match my order form. Just thought I'd check with some tranny guys on more specifics before getting butthurt.
I'm putting a picture to show what I mean.
New on left, old on right. Old drum shows 2 cutouts between teeth, new only has 1 shallow cutout
Last edited by devilschariot; 08-03-2015 at 02:10 PM.
Re: '86 700r4 Reverse input drum variance, new vs old
That is the balance marks or areas where metal is removed to get the correct balance needed. The one on the left was not that far off, that is why less metal was removed. You will need the aluminum piston to go with the drum as the steel one will not work. Install the aluminum piston "as is". Do not block or modify the holes in the aluminum piston. Use the waved steel and use the early 1982 - 1986 reverse/input clutches, and not the late 1987 & up type. Use the "turbulator" steels (1996 & up) if you can. The stack up is one waved, then a flat steel, clutch, flat steel, clutch, flat steel, clutch, flat steel, clutch, pressure plate, snap ring. .035" - .070" clutch clearance here. This is the best way here to get long life and not use the belville steel which chews up the drum. I setup all of my kits this way. Use Borg Warner clutches here, as they are the best in terms of quality.
Last edited by Pro Built Automatics; 08-06-2015 at 12:52 AM.
Re: '86 700r4 Reverse input drum variance, new vs old
Awesome ^ Thank you both. There is a lot of conflicting info on the interwebs, so it's good to get some clear answers.
This is my first rebuild, but I have it under control in most aspects. It seems the later model drum is mostly what vendors stock, and this particular issue was unexpected, which is why I have 0 knowledge on it. But I want to get it correct, regardless. Is there a specific vendor anyone can recommend to get the internals for this drum? I've found bits and pieces across vendors, but I'd like to find it all under 1 roof. Bulkparts doesn't offer the aluminum piston anymore.
Also, any tips on getting the piston into the drum without shearing the seal? I know it's kind of awkward seating in the steel piston, so I assume it will be equally so with the aluminum one.
Thanks for the patience. I don't claim to know what I'm doing quite yet, but my objectives are clear....just my methods that need some fine tuning. I'll get there with time and good advice.
Re: '86 700r4 Reverse input drum variance, new vs old
It doesn't show any lip seals, but the photo below does show the two items I used to install the pistons with lip seals.
Lots of assembly lube and the lip seal tool that came with my Pro-Built kit. I have a lip seal tool that looks like a giant feeler gauge but the Lip Wizard seemed to be easier to use.
Re: '86 700r4 Reverse input drum variance, new vs old
Did you use any sort of compression tool to press it in, or was it just patience with hand pressure and gently working that seal around with the seal installer tool? I'll grab some of that thick assembly lube, I've been putting that off long enough.
Trying to prevent a shear, as that's another 2 or 3 day delay waiting on seals.
Re: '86 700r4 Reverse input drum variance, new vs old
Originally Posted by devilschariot
Did you use any sort of compression tool to press it in, or was it just patience with hand pressure and gently working that seal around with the seal installer tool? I'll grab some of that thick assembly lube, I've been putting that off long enough.
Trying to prevent a shear, as that's another 2 or 3 day delay waiting on seals.
I just used gentle hand pressure while rotating the plastic disk around the drum. It kind of just dropped in. IIRC, some lip seals like the ones at the back of the case (reverse clutches) went in pretty easy without that plastic disc.
Use the thin, less viscous assembly lube on everything - seals, gears, bushings, etc. Use the thick, viscous lube to hold the check ***** in place. Some people use Vaseline for the thick stuff but I just used assembly lube (what I've seen in books and videos).
The nice thing about bench work is you don't have to fight gravity.
Re: '86 700r4 Reverse input drum variance, new vs old
If you need an aluminum piston, any transmission shop should have extras as they are in everything since 1987. If you cannot locate one, let me know and I will get one out to you.
08-03-2015, 02:02 PM
