A few days ago I swapped a used C6 into my truck, replacing the original AOD.

It's driving & shifting fine, except that it engages pretty hard into reverse - selecting any forward gear feels normal.
Idle rpm, diff/driveshaft, & mounts are all good.....symptom only started with C6.

Is there a likely cause for this?

A rebuilder opened & checked over the transmission before I installed it & said it all looked good, so closed it up with new gaskets, modulator, fluid & filters, intermediate band adjusted.

Thanks for any help

 

Can you explain a little more for me? Does it bang and away she goes or like slipping time for it to catch? Does it make any noises? Mine started doing this and ended up loosing third gear. Diagnosis, high reverse clutch pack problem.

 

Well, it's fine for all forward gears - just engages softly as normal, no delays when cold, shifts firm & quick, & no slipping.

Reverse engages quickly too, but instead of just a nudge on engaging, it's a pretty hard thump (at idle). Once engaged, there's no other problem in reverse.

No noises or vibrations etc

 

To be honest, that sounds more like its in the drive train past the trans. Have you checked the u joints, up and down, back and forth?

 

They're all fine; & the rear axle backlash - it's only since the C6 swap that there's been this problem

 

Trans mount and others good? If you have eliminated everything else to include top and bottom screens on the control valve, fluid, can't think of anything else on outside.

 

It's not that I doubt you, it's just usually easier and not as expensive to check everything else first. Besides, you will know what it is once everything else is eliminated. According to what I'm reading in reverse there's no band applied, the High/Reverse clutch and the Low/Reverse clutch are applied. Got/get a book and do the oil pressure and other checks but all indications are leaning toward tear down.
Sorry

 

Thanks for the help Chiefrider007.

I'm suspicious the problem is in the valvebody.......for the first day after the swap, the governor was sticky (ok after some driving) & I think maybe I have a sticking valve causing this problem.
I'll give it a little time, then try a fluid treatment & go from there.

 

If its not slipping that's one thing but I wouldn't move it if it is. The farther you drive the more it will cost. Lots of things cause weird things like if your cross member bolts are loose. Funny

 

I hope you get it figured out soon and ya just gotta let me know cause it's starting to bug me..

 

No slipping - driving perfectly, just this harsh engaging on reverse

You'll be the first to know!

 

Find out anything?

 

Well, from inquiries, it looks like it possibly could be a valve body issue (so I poured a bottle of LubeGard in for good measure)........ but more likely wear in the direct clutch or rear band.
This evidently matches the symptoms this trans is giving & needs a strip down to correct .

But I haven't had it looked at yet. I'll clock up a few more miles first & see if anything changes.

 

Wouldn't be hard to swap out the valve body to see. There's only one band, intermediate, in the C-6, it allows the 2nd to 3rd shift. Mine just did the noise in reverse a few times this winter then wouldn't go into reverse one day so i rolled it forward and then back and gave it extra throttle, went into reverse for the last time that day. Bellville spring broke and smoked my reverse/high clutches...New rebuild kit came today so with luck I'll have it done next week.

 

Well, a month of driving made no difference to any possible sticking valves etc, so I took it in for checking over. The trans mechanic took pressure readings etc which he said were all high but within spec.
So we backed off the modulator slightly, lowered the idle a bit more, fixed a couple of small vacuum leaks & he took it for a drive.
It all definitely helped, but he thinks a shift kit has been fitted that has boosted the line pressure - & reverse operates at twice the pressure of the forward gears anyway - so he was confident that there is nothing to worry about.

It certainly is driving & shifting well, so I'll see how it goes