I am almost finished with my 86 IROC project, i bought it with no motor or trans, i had a 350 and bought a 700R4 used from a fellow member. So I got the engine running great, go to put it in reverse and nothing, i have no gears, not even the clunk of shifing in any gears. I know it has fluid, i have the bolts tight on the flywheel, the torque converter is seated properly, what else am i forgetting? I really need some answers, all of my mechanic friends are manual transmissions only.

 

Remove a cooler line and start does fluid spray out?
You said bought it used is there a filter in it ?
Is the trans and 86 and later 30 spline if not is the correct converter installed ?

 

reverse uses the most pressure in terms of applying the clutch pack, so when you lose reverse its a giveaway that your not getting the fluid to where it needs to be and do what it needs to do. id say look at the fluid and the pan and check for metal or anything like that. but it may be possible that you need a new pump

 

When the pan is down make sure the TV valve is still in the front pump, you'd see it in the pan, unless somebody has been in there before and forgot to reinstall it.

 

check the fluid. these trannys have about approx 11 qts that go into them. depending on the torque converter. Mine did the same thing rebuilt tranny i filled it and sat there while its running and slowly shifting in all gears to get fluid running in them. and then it works great.