8 1/4 Rears - any good?

[DYNO360]

I have a '74 B body that I would like to run in street stock. It has an 8 1/4 rear. Will they hold up under circle track conditions? I know that they are not good in a drag race. Also, it has a "Sure-Grip" carrier. Has anyone had success using this over welded-up spider gears? I understand that a 1973 8 3/4 will bolt in with only the driveshaft to be shortened a bit. That is a lot of work and more expensive, but may be the best way if the 8 1/4 is a piece of junk. Help! I need your advice, 'cause April is approaching fast.

[Rich33]

I say toss the 8 and 1/4 and put the 8 and 3/4 in. Those sure grips tend to give out under circle track conditions and you'll want to stay away from a "C" clip sytle rear end. I've ran welded spiders for years (too cheap to buy the spool) and haven't had problems.

The only problem I've had with 8 and 3/4 rear ends is with the oil seals. If you don't replace them they'll leak after a few races and then you've got gear lube all over the rear brakes. It's a pain changing on the axle and I usually end up having to torch off the old axle bearing before installing a seal and pressing the new bearing.

[dirttrackracer]

I ran the 8 1/4 for 4 yrs on the dirt in a simular car with welded spiders,had a pinion bearing go out the third year otherwise no problems. these were my first years of racing any the car took a lot of abuse (crashes). the suregrip would last a while on the dirt but locked up rear would be easyer to setup car handleing. I have a 4.10-1 and a 3.50-1 gears I'll sell cheap if your looking. good luck.

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[DYNO360]

Thanks dirtrack, I would be interested in the ring & pinions. Go to my website, www.southernracer.com and e-mail the prices.

[RamHead]

dyno 360,
I also run the 8 1/4 on 3/8 dirt. welded spiders. no real problem compared to the chevy's. The track will let us run the 9" ford's haven't had the need.

RamHead

[RamHead]

dirtrackracer,
If dyno isn't interested in 4:10 I am!
reply HALETM491@CS.COM

RamHead

[AVENGER29]

My 2 cents worth,mopar fanatic, but i wouldnt run the 8 1/4 or anything else but ford 9 inch, you can build a bullet proof 9 inch for 1/3 of the money you may spend in a so so reliable 8 3/4. Parts for the 9 inch are dirt cheap,gears run from $130 to $250,mini spool from $20.00 to $40.00 and pin around $15. Make sure you run a high quality gear oil,we run lubrication engineer, we are going thru our winter normal tear downs, current rear end has 3 seasons,looks like the day it was put together.
luke

[1972cuda340]

I don't know if I'd run welded rear I've seen them come apart. The guy who does them has to know what he is doing, I don't think it is a do it yourself project.

I run a 3.55 8 1/4 posi, but the posi started to loosen up too much so I shimmed it for more load and now it acts like it is locked but no welding required.

I know others weld and I've seen welded run with no problems, just hate to see someone blow a rear, and then that sometimes ruins the ring and pinion.

[dwc43]

I've run the same 8 3/4 with welded gears for 8 years and never had a prob with it. THe 8 1/4 is a replacement rear for the 3/4. The 1/4 does not have the case flex probs the 3/4 has. The 3/4 flex problems can wear gears,break caps,and axles. Mosier makes a back brace for the 3/4 to prevent this. The 1/4's only weakness if it has one is the use of c clips, but mosier makes a c clip eliminator for these to. The ferd 9 inch also has flex problems and there is a back brace for them as well. The ferd 9 inch creates too much heat nad needs a cooler to make it survive. The 9 inch is also much MORE expensive to build than a 1/4 or 3/4.

[brian sauser]

With what I have found for parts, I can get any gear for a 9 inch for $115, mini spool $30, bearings and grease are the same amount I believe. Plus if you go to another track and your gear is wrong, every modified racer uses a 9 inch, you could get a get of gears from someone to use for the night. We have ran 3 speed manual transmissions and run them in direct drive, 3rd, instead of running them in 2nd and loosing HP by running through the countershaft. I have yet to find a 6.50 or 6.00 gear in any other brand but the 9 inch. I also believe the 9 inch is stronger with the 3rd bearing on the pinion shaft.

I am building my car right now, with a 3 speed manual trans, 9 inch rearend, and 5.43 gears to turn 5800 RPM's on a 3/8 mile asphalt track.

I believe that by running a 9 inch rearend if you have problems with your gears, you have a better chance of racing that night by getting a gear from someone to use for that night.

[340duster1]

Another source for gears are dakota pick-up trucks. You can only interchange the gears as there is a different spline on the axles. there are 3:92's and 3:55's available in these trucks.

I am presently installing a set of 3:92's from a dakota in a 74 duster 8.25. This is for a street driven car, not my circle track car. I have a 8.75 in my dirt track car.

As far as using the 8.25, I would avoid it unless the issue is budget. Having said that, the 8.25 has larger axles than a chevy 10 bolt.

If you decide to run it do regular inspections on the c-clips, cross shaft and the differential bearings: because this is where the cornering loads go. On the 8.75 thecorner loads are on the axle bearings.

Just my two cents