PDA

View Full Version : AW4 Delayed Reverse


wireman121
October 22nd, 2017, 14:29
I've been looking all over for some help with this. I read through the AW4 manual, but it leaves out much mention of the first/reverse brake which is where I suspect my problem is. Anytime I shift into reverse, there is about a 3 second delay until reverse engages. Once its engaged it is strong. Everything else in the trans works perfectly. I've had this since I got the truck which is about 4 years ago, but I've always wondered if this was something easily fixed like a broken spring or leaking o-ring (one of those oil tubes handles first/reverse brake I think?, does it have o-rings?)

I've seen a few posts about this, but never any resolution. Before I pull the pan, I'd like to know if there is anything common I should be looking for. I'm really not interested in tearing everything apart and rebuilding since the 3 second delay is something i can just deal with until something more goes requiring a rebuild but if its something i can fix just by pulling the pan, I'm game.

I do have another XJ that I've compared it to and this is the only thing different with the trans...

90xj06
October 22nd, 2017, 17:02
the only think i know is that reverse is controlled only by the shift lever. and nothing electronic.

have you changed the fluid recently?

does it get any quicker if you rev the engine a little higher than idle.

what year is the jeep? it may just benefit from a filter screen replacement and some new fluid.

wireman121
October 22nd, 2017, 19:43
It did have a filter and fluid change when i first got it. I will test revving and going into reverse tomorrow. I believe it takes same time to engage regardless of RPMs.

Runnin'OnEmpty
October 23rd, 2017, 09:59
You might try adding a bottle of LubeGard in the red bottle to the
transmission. If a valve is sticking, that may loosen it up after a while. The LubeGard is not snake oil, it really works. I've used it
in all my transmissions for years.

wireman121
October 23rd, 2017, 11:42
Well I'm trying to find clarification on what components actually control the first/reverse brake. The manual shows it, but doesn't mention what solenoids, accumulators, etc are involved.

lawsoncl
October 23rd, 2017, 21:36
The FSM mentions timing how fast drive and reverse engages. It says:

Engagement time in D range should be a maximum of 1.2 seconds. Engagement time for Reverse should be a maximum of 1.5 seconds.

TIMELAGTEST ANALYSIS
If engagement time is longer than specified for D
range, check for the following:
• shift cable misadjusted
• line pressure low
• forward clutch worn
• overdrive clutch worn or damaged

If engagement time is longer than specified for
Reverse, check for the following:
• shift cable misadjusted
• line pressure low
• direct clutch worn
• first/reverse brake worn
• overdrive clutch worn or damaged

Ecomike
October 24th, 2017, 15:37
I have been using Trans-X for 40 years, same thing. It cleans / dissolves the gummy varnish build up that makes the valves stick. Sticking is worse when the unit is cold!!! I have fixed 3 AW4s for years, 5-8 years with it when they did that.

For now your problem is varnish, use a pint of Trans-X. It dissolves the varnish fast.

You might try adding a bottle of LubeGard in the red bottle to the
transmission. If a valve is sticking, that may loosen it up after a while. The LubeGard is not snake oil, it really works. I've used it
in all my transmissions for years.

wireman121
October 24th, 2017, 16:55
Alright I will give it a try. Thanks!