Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (
-   Transmission - Rearend (
-   -   all that work....all that money, WAISTED!!!!! (

chevyelc81 08-04-2002 07:11 PM

all that work....all that money, WAISTED!!!!!
Don't you just hate it when you spend money alot of money and time on something and in the end it just breaks!! WHY!!

Here's the story;
In my 1969 camaro, I spent a good $300 on a set of 3.73 richmond gears and an installation kit. I spent a weekend pulling the rear end out, putting all new polyurethane bushings in, sandblasting everything, and painting and undercoating everything. Wile the rear end was out, I put all new bearings and seals in it. I installed the gears, but the ring gear wasn't close enough to the pinion gear. So I picked up a Mr. Gasket ring gear spacer. I installed that behind the ring gear with new grade 8 bolts and everything went together well with a little shim adjustment. Last night I finally got everything together and took it out for a cruise. It worked fine. The only thing I noticed is that there was a very quiet whining sound when you were slighly on the gas. I took the car to the nearest crusing area(Worcester, MA) which is 40 min. away from me all highway driving. It made it there fine, besides reving 4000rpm doing 70mph. I crused around for about 2 hours, just stop and go traffic. Everything was fine. Then just as I was about to leave, I heard a loud bang, and it sounded like something was dragging. I pulled over right away, looked under the car, nothing was there. So I went to move forward, and nothing happened. With the car in first, and the clutch out, I looked under the car and the drive shaft was spinning but the car wasn't going anywhere. I felt the rear end housing and it was very hot. After pulling an all nighter waiting for a tow truck, and getting my car home at 7:00 am. I pulled the rear end cover off and noticed that all 10 bolts holding the ring gear to the posi unit were broken and laying on the bottom of the rear end. The ring gear was loose on the differential. The only hard driving I did was racing a firebird for about 30 ft, and with a bald set of 235/60's on the back, I just spun, there was no real harsh torque on the gears. I don't understand how this can happen and why it happened. I torqued all the bolts to the right specs and used lock tight. How did this happen???? 08-05-2002 10:29 AM

I'll give this one a try. As it is with probably everyone else who has read this, I have never heard of this problem. Seems at first blush to be impossible, but since you did it it is possible! I can say with certainty, the bolts aren't the problem. If they were installed properly, they are several times stronger than any stress your engine can put on them. However, if they are improperly installed (not torqued properly), they should be expected to fail very quickly with moderate power as you found out. Torque on a bolt is actually a measurement of how much a bolt is streached lengthwise. When put in the proper tension bolts are relatively very strong. In this condition, they actually carry none of the twisting load, it is being transferred from the gear to the carrier by the friction between the two caused by the bolt tension. Somehow, your bolts weren't tensioned properly in the beginning or loosened up very quickly and then broke.

You need to do some detective work. Are you sure that when you put the torque on the bolts that they were actually squeezing the gear to the carrier or were they bottoming out on something? Did you use new lock washers - clean the holes before using locktite (maybe the bolts backed out for their initial tension). I've never used a gear spacer ring but it sounds like this might be a contributor. Double check your tourque spec - maybe you used too much torque by picking the wrong bolt size off a chart and failed the bolts at installation time.

axle bastard 08-05-2002 10:38 AM

were the bolts long enough with the spacer??
i have installed many a ring gear and never has a kit come with lock washers, new ring gear bolts but NEVER lock washers.

[ August 05, 2002: Message edited by: axle bastard ]</p>

Madd Syntst 08-05-2002 11:15 AM

Next time take 146 through Whitinsville, pick up 122 and go to Rockdale. Follow the Mumford river back to Uxbridge, and go back to Woonsocket for pizza. :eek: 08-05-2002 11:34 AM

I've only done a couple of rear ends and those were several years ago so I forgot they don't use lock washers. Regardless the principles still apply - sure looks like the bolts either didn't get torqued properly or backed out for some reason.

chevyelc81 08-05-2002 12:46 PM

The bolts were long enough, they came with the ring gear spacer. They didn't have lock washers so I used the old ones. They might have bottomed out on the ring gear, because I did torque each bolt to 35 foot pounds as specified in the intallation kit for 3/8 bolts. Does that sound right? But thats the only thing I can think, is they bottomed out. I'll try insatalling everything again double checking everything and I'll let you guy's know what happens. Thanx for the reply's.

Hilbilly 08-05-2002 05:38 PM

My two cents worth. Have used ring gear spacer before with out any problems. Did you make sure that the ring gear and pinion pattern was ok. The whinnig leads me to beleave that could have been your problem. COuld it have been that something locked and shered the bolts. On another note did you remember to put gear oil back in it, the right type. That comes under I've been there and done that burned up a rear by that one my no one shpuld know why . <img src="graemlins/nono.gif" border="0" alt="[nono]" />

Jim Weeks 08-05-2002 06:03 PM

Another idea for you is to check the accuracy of your torque wrench. When I was in trade school a guy had built an engine, unknowingly using a defective torque wrench. After driving the car for 15 minutes the engine fell apart just like your diferential did. After investigating the problem for days they checked his torque wrench against another one of known good quality and his was way off. Just a thought.

axle bastard 08-05-2002 07:04 PM

ring gear to carrier specs are 80 ft lbs if my memory is working properly. touque wrench. good thought. leaving the torque wrench "loaded" will surely throw it off
80 ft lbs for a gm 8 1/2.

[ August 05, 2002: Message edited by: axle bastard ]</p>

chevyelc81 08-05-2002 08:32 PM

I would shoot myself if I forgot to put the gear oil back in. I put 2 quarts of 85W-140 gear oil in and a squeeze tube of limited slip oil. I definatly made sure I put oil in it. The torque wrench I used is a couple of years old, so that might have been the problem, and the torque specs really don't sound right to me. I think 35 ft lbs is a little under torqued. Ill call a rear end shop and see what they say for that size rear end. Once again, Thank you very much for the input.

4 Jaw Chuck 08-06-2002 12:19 AM

What did you preload the pinion nut too? Did you use new bearings in the pinion? There is a spec that varies between 5-23 inch pounds of preload or drag on the pinion assy, I hope you used a new collapseable sleeve? Sounds to me like the pinion did not have enough preload and it "bit" the ring gear, this usually shears all the bolts on the ring gear or grenades the case.

Hate to say it but if this is what happened I would just get an entire new axle, the case spreads and the spider carrier is usually warped not to mention the pinion being bent. We won't discuss what happens to the bearings, you get the picture. I hope this is not what happened. You can tell by checking the preload on the pinion nut with the carrier out, if it is loose or has no preload you will know. The actual torque on the pinion nut varies but is around 100-300 ft pds depending on the axle, the preload torque is the amount of torque it takes to rotate the pinion once assembled in the case and the nut is tightened. I've seen this a few times before but usually it is caused by drag racing and the collapseable sleeve "collapses" and the preload is gone. When I set up an axle for abuse I custom machine a solid spacer to replace the collapseable spacer, solves the problem completely.

Hope I'm wrong. :(

axle bastard 08-06-2002 01:53 PM

hey, i spend 8 hrs. a day getting paid to rebuild these things. a gm 10 bolt and 12 bolt are 90 ft lbs. ring to carrier. i doubble checked today!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
i haven't had one failure, ever. a leak maybe, no failures! <img src="graemlins/nono.gif" border="0" alt="[nono]" />

chevyelc81 08-06-2002 09:58 PM

I did use new bearings in the pinion, and I tightened the pinion bolt to where the pinion gear spun with a little bit of drag and with no play in the bearings. The installation kit came with a new collapseable sleeve which I did install. I don't think the gears bit eachother. I think I might know what happened. I was given the wrong torque specs. I torqued all the bolts to 35 foot lbs. I called the Summit tech line and according to Richmond Gears, I was told 45 to 50 foot lbs for the 3/8 bolt on the 8.2 rear ends. I think axle bastard is thinking of the 8.5 ten bolt and 12 bolt rear ends which both use 7/16 bolts. The 8.2 has 3/8 bolts, I would probably strip something or snap a bolt if I torqued them to 90 ft lbs. I think the bolts were just way too loose from the begining, thats why it fell apart. Thanks for the info though, It will be helpful if this ever happens again, hopfully it doesn't.

[ August 07, 2002: Message edited by: chevyelc81 ]</p>

4 Jaw Chuck 08-06-2002 10:55 PM

Rotten luck just the same, hope the next goes better. Sounds like you got your stuff figured out.

axle bastard 08-07-2002 01:05 PM

yep, i was thinking 8.5! sorry

All times are GMT -6. The time now is 09:17 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.