"gripper pattern" u bolt question

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Rapid Robert

Rapid Robert

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for an 8&3/4. I have a set of ubolts from Mancini that have the flattened side on the inside of the radius but they were not long enough. I just ordered a set of longer ones but they do not have this flattened area, mancini calls it a gripper pattern & said that these will not present a problem. What do you guys say? is this going to be a problem or am I OK here? thank you for your time. RR r
 
The originals were flat with a knurl. Many replacements are just round stock. Not a problem at all. Just torque them to spec which is pretty light. Someone will chime in with the spec I'm sure. You don't want to crush or distort the axle tubes by tightening them too tight. .
 
AMK has the correct u bolts, two different lengths. I have seen a couple axle tubes pinched by the round u bolts. I like to use the gripper kind.
 
i just received a set from AMK, They are very nice, i have the 6 5/8 length and they do come with the knurl...Rich
 
If I found a set that didn't have the proper knurl, I'd look REALLY close to make sure they're not Chinese Trash. In a street car, I don't know that the knurl missing is a deal-breaker, but I would never run them without the flat. That flat is what keeps them from crimping your axle. Even if you use the proper torque spec, you're still concentrating that load on a MUCH smaller area.

Call your local truck/axle shop. They might have what you need just laying around.
 
I found AMK but could not find an 1/2-20-3"- 8" or longer knurled set. I will call an axle shop, thank you. this is a dirt track car so I do need the best. RR
 
Both my 62 and 64 b-bodies with original 8 3/4 rears, 64 is an original 8 3/4 Sure-Grip, do not have the flat top knurl u-bolts.
When I rebuilt the 62 rear I put the flat u-bolts on it, fearing the worst.
Just redid the 64, couldn't find the flat top ones, bought them from Espos along with the springs, which are round like the originals.
Torqued to 45 ft/lbs was not much more than what I 'torqued' them to by hand with a small rachet.
 
its looking like I cannot find knurl ones that are long enough for me to use the (Mrrandy) tie down plate. I may have to forgo that for now (especially since I cant find Mrrandys site to order the plate). RR
 
jos51700 said:
In a street car, I don't know that the knurl missing is a deal-breaker, but I would never run them without the flat. That flat is what keeps them from crimping your axle. Even if you use the proper torque spec, you're still concentrating that load on a MUCH smaller area.
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This is exactly correct. A round shaped u-bolt on the clamped area will indent an 8-3/4 housing with factory torque even though that torque is low.
 
I bought new U bolts from Calvert Racing and they aren't flattened or knurled? How bad is it going to hurt my housing to run them. I plan on putting 600 hp to the ground and thought these would be an upgrade. Should I replace them or just torque them and forget about it?

1714040801090.jpeg
 
Does anyone have a photo they'd be willing to share of a housing they've kinked from using round u-bolts (torqued to factory spec)? I used them before and have never kinked an 8-3/4 housing. Maybe I've just gotten lucky.

BrianT said:
I bought new U bolts from Calvert Racing and they aren't flattened or knurled? How bad is it going to hurt my housing to run them. I plan on putting 600 hp to the ground and thought these would be an upgrade. Should I replace them or just torque them and forget about it?

View attachment 1716241358
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I've got the same Calvert u-bolts holding Dana 60 in my '66 Dart. Granted, the Dana's got like 5/16" thick axle tubes, but if it was that much of an issue I'm pretty sure Calvert wouldn't sell them. I'd just tighten them up and send it.
 
Personally I’d like to see some with a larger flat added to the curved area.
 
mopowers said:
Does anyone have a photo they'd be willing to share of a housing they've kinked from using round u-bolts (torqued to factory spec)? I used them before and have never kinked an 8-3/4 housing. Maybe I've just gotten lucky.
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They're all in the trash lol

I look at it like this: the factory did it, and they cut every damn corner that they could as Chrysler was perennially broke (Iococca years notwithstanding). If Chrysler spent money on knurling and flats, then that means the warranty rate justified the expense.

Rick Ehrenberg was selling them on eBay for awhile. You might message him and ask him if he knows of a source. Ricks mopars is his user on eBay. I always find him by looking up 'Mopar problem solver'.
 
When did Chrysler install flat u-bolts?

My original 62 8 3/4, 64 Sure-Grip (tapered axles and all), even my bb 4 speed 67 with torque boxes, none of them came with flat u-bolts.

Recently swapped the rear out of my 64 with a later rearend that had regular u-bolts and 4:10s, changed the springs in the process, neither housing was damaged.
 
mopowers said:
Does anyone have a photo they'd be willing to share of a housing they've kinked from using round u-bolts (torqued to factory spec)?
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Here's what aggravated me. Picture of my back braced 8-3/4 housing being fab'd. What you see is a piece of driveshaft tubing I welded to the housing to shore up future indentations. You can see where the clamp force is concentrated. Doesn't mean the housing is junk though. If the housing ends are still where they are supposed to be, you are good.

backbrace2.jpg
 
DC 340 said:
Here's what aggravated me. Picture of my back braced 8-3/4 housing being fab'd. What you see is a piece of driveshaft tubing I welded to the housing to shore up future indentations. You can see where the clamp force is concentrated. Doesn't mean the housing is junk though. If the housing ends are still where they are supposed to be, you are good.

View attachment 1716242127
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Yeah, that's something I've never seen. Hey, at least the axle tubes aren't kinked.
 
Picture of my housing ends with gage inserted. Mine are not perfect but work OK.

scan0009A.jpg
 
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