Still having 8.75 problems

[64dartgt]

Well...after one attempt to fix my badly whining new 3.55 Motive gears my shop has stopped returning my calls.  Last time I talked to them they seemed to be saying that I just got a bad set and that the best bet was to try a new set of motive.  The other thing is a cyclical growling noise that kicks in around 70mph.  Took it to my usual mechanic and he said it was the rear end.  Before the rear was swapped for this totally rebuilt 8.75 sure grip there were no problems, but we swapped in a rebuilt 340 at the same time.  However, it likely isn't the engine as it stays when you drop it in neutral.

Any clues?  I had the drive shaft balanced and they said it was perfect.

Thanks,

Bob

[elacruze]

Cyclic growling may indicate a bearing problem-assembled too tight, or races installed crooked (dirty housing or poor seating) It could be that the pinion isn't round, or the ring gear is not seated straight causing tight/loose spots.

A new expert may be in order.

[RallyeMike]

I think you should pull the motives and go with going with either Nitro or Yukon.  A few more hundred is worth it for peace and quiet!

(Really..... I think you already arrived at the answer, and it has been backed by another shop).

[64dartgt]

Thanks for the validation.  Just pisses me off.  I took the thing to a diff shot with over 40 years in the same location.  How the hell do these places stay in business if they don't know what they are doing?   

[elacruze]

Thanks for the validation.  Just pisses me off.  I took the thing to a diff shot with over 40 years in the same location.  How the hell do these places stay in business if they don't know what they are doing?   

Neither do their customers. Same happened with my D60, I had to reset the gears myself.

[Cooter]

Thanks for the validation.  Just pisses me off.  I took the thing to a diff shot with over 40 years in the same location.  How the hell do these places stay in business if they don't know what they are doing?  

Obviously, for 40 years, they got at least something correct. This is why when customers come into the shop, the FIRST thing we tell them when they are not doing something OEM, is "Now, we'll do the work and take every step to make sure your happy. However, when you supply your own parts, there is NO WARRANTY if this thing howls, grinds, makes weird noises, etc. We only guarantee the Install"....After that, they have a choice to make. After all, most shops don't make didly sh*t messing with "Hot Rods", or Peoples "Babies" (Ie: Their toys). I get this all the time..."Hey, do you guys even mess with high performance stuff at all? I can't find a shop anywhere that will even touch it?"..This is why...If WE (IE the shop) supply say a rearend for a vehicle and it howls, then we simply call up the yard that sent it and they send out another along with the labor to install another. When it comes to non-OEM stuff (IE Racing parts), the customer usually supplies his/her own parts. This takes the shop out of the equasion. Sorry your rearend howls if it is indeed the gears whining due to incorrect set up, but I think it's a little premature to blame the shop until you find out the gears are actually set up incorrectly.. I mean, backlash and pinion depth are most important, but sometimes a bad set of gears/bearings are to be had. Most bearings/races are made overseas now anyway. I'm not defending the shop in question, just offering the other side of the coin here. My .02

[64dartgt]

Perhaps it  is a bit early to blame the shop...except for lousy customer service.  I am willing to pay to have another set of gears installed, but their failure to return calls is a bit much.  Not too thrilled with motive either.

I can get a set of NOS 3.23's for a decent price...think that is a better option than another set of motives (as the shop recommended) or nitros?

Thanks,

Bob

[elacruze]

You may blame the whine on the gears, but not the growling. Even cheap Chinese bearings won't growl when new if installed correctly.

Being in business for 40 years only means you got away with it, certainly it is no guarantee of high quality. Pity that good shops suffer from their shady brethren.

[RallyeMike]

Being in business for 40 years only means you got away with it, certainly it is no guarantee of high quality. Pity that good shops suffer from their shady brethren

True. True.

Owners changes, employees change...... It's like some of the companies that I look at to work with on projects..... they say their company has 40 years of experience doing something, they rattle off all the high-profile jobs that the company has done, but then you look at the proposals and NONE of the people who worked on those projects are involved. Next .....!

[64dartgt]

Hopefully Wednesday will bring final resolution.  The shop will swap the noisy 3.55s for a known good set of used 3.23's.  Ironically they pulled the 3.23's from another 8.75's they rebuilt for a high dollar car with Motive 3.55's and have a noise problem with that set too.  The other guy has just decided to wait for new 3.55's from US Gear which will be available this spring.  That car is in the middle of a rebuild and won't be mobile for seven months anyway.

Keep you fingers crossed for me!

Just about time to park her for the winter.  My goal has been to get this fixed so I don't have to face this in the spring when I want to drive her.

[64dartgt]

He checked it out today.  Still vibrating after he put it on the lift an pulled the wheels and axles.  Seems to be a worn tailshaft bearing, as it was vibrating at the center of the car even with the axles out.  When the guy (a pro) put the engine in he failed to put a new tranny mount in...which the tranny shop failed to put in when they rebuilt the tranny even though it was absolutely shot according to the engine guy.  He only told me about it when I complained about the noise.   May have contributed to wear of the tail shaft bearing which was nearly coincident with the rear end rebuild/replacement.  The differential guy trued up the axles and we will likely send the car down the street to the tranny guys for a bearing replacement before we look further at the gears/rear diff.   

[64dartgt]

Axles were a tiny bit out..12 and 15 thou vs. a 9 spec.  They are straight now ($190) and things a a little better.  Tail shaft bushing on the tranny is next, plus I will have the tranny shop that did the rebuild (in addition to the bushing) look at the geometry and new tranny mount.   

[64dartgt]

The transmission shop is just a mile down the road from the differential shop.  He didn't seem to think much of them.  He apparently had taken his jeep in and had a bad vibration that couldn't be cured until he bought a new drive shaft.  I hope that the new bushing and straight axles fixes it, otherwise I may swap the tranny mount.  I could have sworn I bought an OEM replacement.

[64dartgt]

Tranny shop said the bushing / play in the drive shaft is fine.  He said that the passenger side tire was wobbling like mad when he ran it on the lift...which was the FIRST stop on this parade.  i.e.  I asked my usual mechanic, the guy that put the engine in for me, to check the rear tire balance.   

[64dartgt]

Took her in to a tire shop to have the tires balanced.  He said the rims were in pretty tough shape but he did his best.  It is much better.  I had her up to 100 yesterday on the highway and, while there was some tire noise, it has stopped growling and shaking. 

Today the car is at the diff shop getting a known quiet set of used 3.23's put in.  I hope this is the end of the saga.  I am considering new rims, but after all I have read about paint flaking off the repro Magnum 500's I may go another path.  Given that I have just bought new tires, I will call a local rim shop that I used to use to do aluminum wheels and see if they can straighten the old 500's.  Otherwise I may seek out a used 500 to replace the one really bad one in the rear.