Any 700R4 gurus out there?

[geekinavette]

Last summer just before CF '05 I did a transmission rebuild on my '84 (which does NOT have the original transmission...it is an 86 or later). It started not wanting to shift, pulled the dipstick and the fluid was just black, with gray streaks in the pan. Rebuild time! (and yes this was my first transmission rebuild). I used a "high-performance" Alto kit from Oregon Performance Transmission.

All was well for roughly 3000 miles, then it started not shifting again. Took the pan off, had LOTS of steel shavings in it. I just got the transmission out and partially disassembled this weekend, so far all I've found is signs of overheating in the forward clutch assembly. None of the friction linings are worn down to the steel, so I've not found the source of the steel shavings yet, but obviously the overheating forward clutch assembly is a problem. I'm looking for where to look for the cause of the overheating forward clutch assembly....fluid leak, tolerances...etc. Here's a picture of the forward clutch assembly:

Not pretty.

Of course I still have to find the source of the steel shavings....but any suggestions on the overheating forward clutch assembly?

Any and all advice appreciated (as long as it's not "just buy a new one"...if I could afford it I would! And besides, I wouldn't learn anything.)

Bill

 

[airman]

Did you blow out your cooling lines ? also some manufacures put a check valve at the cooler as to stop drain back it can become cloged not for sure if that model has one but you should always flush out your cooling lines Also did you change your torque converter ? this should also be changed it could also be the source of your shavings the 700r4 is a very perticular trans and all has to be just right including all your bearings and thrust washers .

 

[geekinavette]

Yep, flushed out all of the cooler lines and the cooler itself. Yes also replaced the torque converter.

I should mention that the forward clutch assembly is the ONLY one that shows signs of overheating...rest of them look fine.

Bill

 

[jeffyc]

do a complete disassembly inspect everything including all bushings, sprags
inspect everything it should be quiet clear what is wearing
did u disassemble the pump?
something wore in the convertor?
fine out where the shavings are coming from clean and rebuild the trany
clean the cooling lines and cooler out
i would say the burning is from it not shifting correctly
do to so shaving has contamined the valvle body or has damaged a seal in the trany
like i said find out where the metal shavings are coming from and go from there

i have gone through my atsg book and well i could type every cause it could be but then i would be naming next to every thing that could go wrong with the trany

 

[G Winter]

I think jeffyc might be onto something with the pump. Pump going bad could cause the poor shifting. Bearings and thrusts need to be looked at very carefully. Are the shavings steel or aluminum? check with a magnet if you can't tell any other way. It has been awhile since I did any auto trans work. Just tossing in a couple ideas.

Glenn

 

[geekinavette]

Shavings are steel

Bill

 

[jeffyc]

i hate to make a pointless post
but my advice right now it to take it apart and inspect everything carefully
then get back to us and let us know whats going on and what questions u have
if u done have the atsg book (automatic transmission service group) get it
i think i paid $15 from summit for it
the info that u gave me i can only give vague answers to.
when u are ready ask what mods u should do to make it more stout if u have not allready i will give u my best advice
i am not a trany pro but i have done my 700r4 and when i had my z28 i used to do my th350 for my self and a few others and also th400's

 

[geekinavette]

Yeah I have the ATSG book, and the GM service manual (they're pretty much the same) as well as the Haynes manual. I still need to dig some more to find out where the steel is coming from.

I did use the "heavy duty" clutch packs, and the "Beast" sunshell...and a few other upgrades that I can't recall at the moment...plus the Transgo kit.

I'll know more this weekend.

Thanks!

Bill

 

[jeffyc]

did u put in the "hi rev" vane rings?

 

[geekinavette]

It's the 13-vane upgrade...don't know about "hi-rev". It never sees more than 5K. I haven't looked at the pump yet.

 

[jeffyc]

u put in the 13 vane?
i heard bad things about that
and it really does not help the trany out
the high rev kit had hardened rings and a new primer spring
if u take alook at alot of trany rebuilders most like 95%+ never put them in
the 13 vane is supposed to create harmonics in the transmission pressure.
i cant remember exactly havic its suppsoed to do to the trany

 

[jeffyc]

after searching for over an hour and 1/2 i found some stuff
but here is a cut and paste off an other site

what do u think about the unbreakable transgo pump rings? I use them in anything that runs high line pressure. While I didnt have any failures before (lucky maybe?) IMO its cheap insurance so if you want to spend the few dollars on them it wont be money wasted IMO.
IMO stick with the stock 10 vane pump though as Ive seen some failures with the 13 vane units with high line pressure. Stick with the stocker 10 vane and youll be fine.

 

[geekinavette]

Got a chance to take the pump apart....it's fine, looks brand new.

I DID find the source of the steel shavings...the snap ring on the "reaction sun gear" was not installed properly. It slid forward in the sun shell and was grinding on the back side of the planetary housing.

Now to find the problem in the forward clutch assy....

 

[geekinavette]

Well I think I found the problem with the forward clutch assembly.

The steel plates in the new clutch pack are .014" thicker than the ones I removed. There was NO clearance at all once the assembly was installed. That'll sure cause it to heat up big time in P R and N.

Live and learn.

Bill

 

[jeffyc]

lol that would do it
ya u should have checked the clearence on origonal assembly

 

[geekinavette]

Well this has been a "live and learn" experience...but finally it is performing just beautifully. I certainly made my share of mistakes...but I have to say I'm glad I went through this as I learned a LOT about how these things work.

I have learned that there were two different thicknesses of steel plates used in the forward clutch assembly, pre-87 (thinner) and 87-up (thicker). However, the kit I bought stated that it was for 82-92 or something like that, which obviously is a pretty serious mistake on the part of the kit vendor.

I also learned that one of the big differences between the earlier and later 700R4 is in the low/reverse clutch and roller assembly. The later models used a little thinner backing plate, and a much thicker roller assembly. I can see why the thicker roller was done, when I took mine apart there were a lot of broken springs in it...very obviously not strong enough. I believe the thinner backing plate "softens the blow" when you put the car into D. Before I replaced the backing plate and roller assy it went into D from N pretty darn hard, and there's really no need for that. Now going into D is nice and "mellow", yet when you hit second you KNOW it! I like it!

I feel I should also report my dealings with the company I bought the kit from, which is Oregon Performance Transmission. The clutches were the Alto Red brand, and I'm not sure of the actual source of the kit itself (I don't believe OPT puts the kits together, but I could be mistaken). OPT was very good during the whole rebuild stage, they did their best to answer questions I had. However, after the fact when I had a problem and identified the discrepency with the forward clutch assembly, communication pretty much just stopped. They answered two of my emails, and took at least a week to do that, then just stopped replying at all. So I would have to say unless you KNOW every little detail to watch for, I can't give OPT a good recommendation.

 

[jeffyc]

congrats man
i am glad to hear your trany is working good
how to rebuild the trany in your vette is a good thing if your like me and plan on keeping it for along time
they are really not that bad to rebuild
and ya the rebuild kits can be kinda weird