"Slapping" transmission

Let me see if I can describe this... Put in 4.10 gears and a LockRite locker at the same time (which replaced stock 3.54's and open spider gears) in a AMC 20 differential with 33" tires. Ever since, the manual transmission gears go "SLAP, Slap, slap slap" when you are decelerating, in-gear, with the clutch pushed in. It feels like the spinning driveshaft's "slapping" the gears to keep up. It's really noticeable when moving slowly in 1st or 2nd. Don't think it's got anything to do with the locker other than possibly a little more slop in the diff. Is it because I installed such low gears? Combination? P.S. still does it after installing a NV4500 w/orig. Dana300. This NV really sounds like a miniature jack hammer over 35 in neutral but that's a different post. Regards, Drink

76 CJ7, GM 350, TPI, NV4500, DANA300 Dana30/AMC20 w1-pc axles, LockRite, 4.10s
Reply to
Drink
Loading thread data ...

I recently heard that kind of noise when decelerating in gear...

I pulled over and disconnected my front hubs before my now dead driveshaft u-joint could take out the yoke too.

I would sure be checking those u-joints out really carefully. The vehicle needs to have the wheels blocked and in neutral when you crawl under to see if there is any play or rust stains around the U-joint caps.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Reply to
Mike Romain

No, Mike. That's not it. The U-joints are fresh and in great shape. It did it before. As a matter of fact, it started after changing to 4.10 gears and the LockRite. Since then, absolutely everything's been upgraded and swapped out except the Dana300. I don't wanna lure anyone into a diagnosis of the transfer case, though, because it really sounds like the tranny.

Here's the timeline recap: Swapped gears&locker myself; slapping has been there ever since. Then dropped in a 350 V-8, NV4500 with all new clutch and components, reinstalled the orig. Dana300, shortened/balanced driveshaft w/new U-joints, had a pro RE-setup the AMC20 just to be sure. Jim

Reply to
Drink

Strange...

It was my 'front' driveshaft that went out by the by and my u-joint is less than a year old.....

I cooked it by being in 4x4 on dry paved roads for too long.

Could it be because the lockRite is being pushed with wheel load instead of drive load? Is there an adjustment in there?

Mike

Dr>

Reply to
Mike Romain

I have 4.10 gears and the full Detroit in my AMC20, and there is no noise.

You said, " Swapped gears&locker myself; slapping has been there ever since." Then you said that you replaced the trans and motor. If the noise was there BEFORE you swapped the trans, what makes youthink the noise is coming from the trans?

I don't recall if you have a CJ5 or CJ7, but if you have a double-cardan joint in the driveshaft, perhaps the center joint is toast. Mine recently took a bye and made a clunking noise, but it was mostly on acceleration and your noise is on decelleration.

You also said that "absolutely everything has been swapped out, except the D300." Why does the D300 escape scrutiny? Also, the gear set (R&P) has to be set up properly, did you do that? It can create noises that can travel up the driveshaft and sound like the transmission.

Knowing from personal experience how much torque steer there can be in a CJ, have you removed the rear drive shaft and drive on the front one to see if the noise remains? If the noise goes away, you'll have a pretty good chance that the trans isn't the object of your obsession, if the noise remains, then you still have the tcase in the picture, but you'll know the rear gear set is okay.

Reply to
Jeff Strickland

Sure isn't any adjustment for the locker. It simply replaces the spider gears and, instead of distributing torque to the fast wheel, it locks the slow wheel. The only thing that strikes me is that it amounts for a little more play than the spider. In straight movement, the locker should be out of the picture since both wheels are turning at the same rate just like the spider. So, could it be that a) the very low gear is doing it, b) the added backlash of the locker allows enough play to "slap" the tranny gears, or c) both? Thanks for the advice, Mike (and anyone else who has any ideas). Best Regards, Jim

Reply to
Drink

4.10 is not very low ratio. There is 4.56, 4.88, and 5. that are lower. The R&P have an adjustment for mesh that is critical, and you could be feeling/hearing the affects of having any one of several adjustments not set right. The pinion gear has to be spaced properly with washers, and if there is slop, the pinion can slide in and out of the pumpkin. The ring gear has to be mounted well to the carrier, and if the bolts are not tightened well, the ring gear will give you troubles. The ring and pinion have to be adjusted properly to each other, and there will be noises if this adjustment is not correct.
Reply to
Jeff Strickland

Thanks Jeff. I haven't really ruled out the T-case. But, this became an issue immediately upon R&P swap/Locker install. I'd try some of the other advice but I'm in the middle of the project (for the past many years:) I hit a deal on the engine and haven't swapped the front gears yet. Gotta get the front shaft cut to fit as well. I had a professional transmission shop set up the rear end Again to rule out my own incompetence. Haha! And, if you can believe it, I'm considering swapping to Dana44's or GM 10/12 bolt axles after everything I've invested. You make a good point about it not being the trans. Although the slapping sounds like its in the gearbox, I know it's differential-related and that's what I don't get yet. I'll have to see if I can ssttrrreeeeetch the front shaft just enough to give it a walk around the block. Pretty sure it's not long enough, though. P.S. How difficult would it be to just say, "to heck with it" and put in Dana44's from a 79 Cherokee (front discs, six-lug wheels)? Or, would a

10/12 bolt from a suburban or blazer be better? Jim '76 CJ-7: Dana30 / Chevy 350 TPI / NV4500 / Dana300 / AMC20

"Jeff Strickland" wrote in message news:nuedndldRJ9dkjvenZ2dnUVZ snipped-for-privacy@ez2.net...

Reply to
Drink

Just to add my two cents in, I also have an AMC 20 with full detroit, 4.10 gears, D 300, but AX15 tranny with adapter, no tranny noise or problems, I'd be checking the D300 too, and as I just helped my daughter replace her u joint in her double cardon drive shaft at only one year old, ( driveshaft, not daughter ), we couldn't get any movement out of it in nuetral with no load on it, but as soon as we dissconnected it the cap that had no bearings left in it fell off, so like Mike said check those again too.

Reply to
Greg

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.