C4 slams into Reverse and makes tire squeal

[Bronco_007]

I just bought another 1974. The C4 has been rebuilt per the previous owner. Factory 302 engine. Dana 20 looks fine. Pinion angles look ok too. Factory front disc and rear drums. Marti report says 3.50 w/ limited slip. The tires are 265/75/16 and need to be replaced (old, not bald). When I put the truck in Drive it seems to fall into gear normally. Same goes for lower drive gears. It shifts smoothly when going down the road. But when I put it in Reverse, from either Park or Neutral, it slams into Reverse so hard that the rear tire will squeal unless I am standing on the brake pedal. I’d guess it only spins the wheel about six inches, and the truck stays in place. I’ve read that this is normal to some extent. Is that true??? Slamming into gear seems a fairly common report, but with such force as to burn rubber…? That seems excessive and potentially unsafe. Any fixes? Transmission fluid change this weekend along with all other fluids so I’m hopeful that could help. Wonder if I can post a video? Any advice is much appreciated!

 

[Rustytruck]

Check your drive shaft.for bad u-joint

 

[DirtDonk]

That does seem excessive.
Broncos have been noted for having noticeable shifts out of park in either direction, but not enough to squeal the tires or force things to move against the brakes.
What is your idle speed in neutral?
Yes it should affect both drive and reverse somewhat equally, but there are other variables.
I don’t know if modulators come into play during this, or not, but more likely than anything else I think something was misplaced or left out during the rebuild.
Shift kits are often installed thinking it’s an improvement, which it might’ve been for a passenger car, but Broncos shifted fairly firmly from the factory.
Don’t know that they were always an advantage in a bronco.

 

[Broncobowsher]

My guess is the low/reverse band out of adjustment. Don't feel it in drive as that band is NOT used in 1st gear unless manually shifted into 1st gear. So it might have an incorrect shift manually downshifting into 1st at speed. The band is only used in 1st gear for engine braking, not normal forward driving.

 

[Bronco_007]

My guess is the low/reverse band out of adjustment. Don't feel it in drive as that band is NOT used in 1st gear unless manually shifted into 1st gear. So it might have an incorrect shift manually downshifting into 1st at speed. The band is only used in 1st gear for engine braking, not normal forward driving.

How is that fixed? Back to the transmission rebuilder?

 

[Bronco_007]

That does seem excessive.
Broncos have been noted for having noticeable shifts out of park in either direction, but not enough to squeal the tires or force things to move against the brakes.
What is your idle speed in neutral?
Yes it should affect both drive and reverse somewhat equally, but there are other variables.
I don’t know if modulators come into play during this, or not, but more likely than anything else I think something was misplaced or left out during the rebuild.
Shift kits are often installed thinking it’s an improvement, which it might’ve been for a passenger car, but Broncos shifted fairly firmly from the factory.
Don’t know that they were always an advantage in a bronco.

I don’t have a tachometer so I don’t know idle speed.

 

[Broncobowsher]

I have not done a C4 adjustment since about '95. Viperwolf would be the local expert around here. If not I am sure there are online instructions. Should be an external adjustment. Loosen a lock nut, torque to spec, loosen a prescribed amount, tighten the lock nut. The band may not have settled when it was rebuilt and now it is loose. The apply of start gentle then hold tight, skipps the apply gentle as it takes up the slack and goes straight to hold tight by the time the band hits the drum.

Guessing idle speed is a sure way to be way wrong about it.