no reverse, no engine brake with 46re

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vk2001

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2001
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318 cid 90' V-8 OHV
Hello!

My new-to-me 2001 ram 1500 has no reverse or engine brake, and despite much reading here and elsewhere, I'm a bit confused.

Does anyone know whether a broken overdrive snap ring would cause a loss of engine braking?

The Truck:
2001 Dodge Ram 1500
210k miles
46re transmission

Symptoms:
No reverse
No engine brake in any gear range

All other gears shift smoothly in all gear ranges (including 1)

Steps so far:
Fluid level is good, and the fluid looks fairly clean and not burnt.
CEL has not turned on.
OBDII scan showed TPS (which I think is a separate issue), but no other codes. I sadly don't have access to a scanner that shows transmission codes.
Checked the shift linkage.

Prognosis:
What are the most common issues that can cause this combination of symptoms?
I don't think it's rear bands, since it drives fine in Low.
Could it be a broken overdrive snap ring (does that stop the engine brake?)
Could it be a solenoid (wouldn't the other gears be having trouble shifting?)
Could it be a stuck piston (again, wouldn't that make it not drive in Low?)

I'm kind of at a loss here. Any ideas?

The only other thing I can think to do is drop the pan and take a look.

Thank you in advance for any advice!
 

EvilSpirit

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5.9 Magnum
The rear band is applied in reverse and MANUAL low. It is not applied in drive - rear over-running clutch provides low gear in drive - the rear band is only applied in manual low to provide engine braking. Good test is to put truck in manual low and accelerate to 15-20 mph and let off the gas - no engine braking means a broken rear band or servo issues. Both common.

That said, while it could be the direct overdrive clutch slipping - they also usually also slip in first.
 
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vk2001

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Thank you for the quick reply! There is, indeed, no engine braking in manual low.

So do I understand correctly that the rear band is not applied in manual low to move forward, but only for engine braking?

If so, then I guess I'm likely looking at rear band or related issues.
 

EvilSpirit

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Correct - in stock applications, the rear band is mainly for engine braking in manual low. In drive, 1st gear is the rear clutch applied and the rear sprag (over-running clutch) holding the drum from spinning clockwise (from rear) - the sprag only allows the rear drum to rotate CCW. While moving at slow speeds in drive, let off the gas and the rear clutch drum is allowed to rotate CCW and the truck coasts. In M1, the rear (low/reverse) band is also applied, stopping the drum from rotating CCW and allowing engine braking. Not only does the rear band being applied allow engine braking, it also protects the sprag from shock loading and case failure, effectively increasing the holding power of first gear.

The reason they don't apply the rear band in drive is to clean up the 1-2 shift. In drive, the 1-2 shift is pretty simple - the front band applies, the sprag over-runs instantly, allowing rear drum rotation, and the shift is complete. In M1, it's a timing issue - the rear band also must release, and timing the front band apply and the rear band release can be tricky. Good shift kits go to great lengths to address this issue, but it is rare to find a kit that totally cleans up the 1-2 manual shift.

It could be that the rear band is so far out of adjustment it no longer applies, but I doubt it. If your trans is hurt, the damage could be as simple as a broken strut to as bad as the rear servo broke and damaged the case. Good luck with your repair. Willie
 
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vk2001

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Thank you very much for your help. The rear band servo piston plug was shorn in half. I am in the process of replacing it now. I rebuilt the valve body for good measure, since I had it out (it needed the overdrive accumulator spring and the overdrive piston).

I got a replacement plug for the existing servo piston, but it is slightly (maybe 25mm?) longer than the original. Should I be concerned about the discrepancy? Can the rear band adjustment take up the pressure from the extra length?

Thanks again!
 
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