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Pinion Snubber


Guest Anonymous

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Guest Anonymous

You guys are all familiar with the concept of a pinion snubber so I'll just get into the idea and state why I think it may a good way to go.

 

I would fab-up a frame work (o/To) that would attach to the existing "snubber" (rubber strap) mounts that the rubber snubber would screw into. Close enough to be able to screw the snubber down and be snug against the top of the diff. (If memory serves me right they have about 2" of thread?).

 

That way I could still have the insulating effect of the rubber mount. It would be adjustable. It would be a part of the chassis and therefore non-intrusive to any of the original Z parts (I'm trying to keep all the "improvements" as close to z-ness as possible to keep things simple for my simple mind).

 

Questions:

Would the mounting point described be strong enough?

 

Does the diff have any opportunity to "wiggle" around the snubber? (The sunbbers I have experience with are conical in shape. Maybe I can find one that's rectangular)

 

Would the snubber "give" too much to be effective?

 

What do you guys think?

 

Thanks.

 

Jon

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should be ok. i went cheapo and replaced the strap with a nylon strap used for carrying stuff on top of your car, thickest and shortest i could find with a rachet, put it where the strap used to be drilled a whole through both sides, and put a poly bumpstop in the center, shimmed it a little on every side the bolt went thru, and snugged it up. then i put the diff back in, and racheted it until it was preloaded nice enough, and prompty reconnected my driveline and went out and drove carefully for a few days straight, looked back up in there, and we good. the solid method with the bumpstop should work great as well, it does not have to be super crazy thick, but it would be nice, the bumpstop allows diff some play, making it so nice and quiet back there now compared to my old solid x member job, much nicer.

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Guest kc6wfs

Jon,

I think it a great idea.

I can't see the diff having any side to side play.

I think I'll get a bump stop from like a camaro and play with that.

My strap is toast and have some driveline vibs when I go uphill for some reason..

More weight on the rear, bringing it lower I think.

I think i'll hit the JY's Sat. Need to find 2 turbo's also!!

 

Dave

 

cheers.gif

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Guest Anonymous

Yup, I have something like what scottieGNZ has now except I used two pieces of 16 gauge doubled up. It's a nice idea because the threaded holes are already in the crossmember. 2thumbs.gif I found out early that the cable JTR recommends is easy but it stretches quickly and needs constant tightening.

 

I thought a pinion snubber might be nicer because once it's in the car I won't have to remove it.

 

Maybe I'm over thinking it. twak.gif

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One thing I like about the above-the-nose differential mount that Ron Tyler made me is that if you want to, you could remove the center of the stock front diff crossmember, leaving only the ends that hold the front control arm bushings to the unibody. That way you can run exhaust easier. This is what Ron has done on one of the cars he built.

 

If you're going to the trouble of building something like a pinion snubber, why not just build the mount I have and gain exhaust clearance?

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There's another advantage to Ron Tyler's (I have to start calling it that instead of Pete's. Not to diss Pete, just got to give credit where it is due) mount. It allows you to mount the front of the diff lower to get better alignment. This is the mount I'm making for when I do my R200 swap.

 

While I'm here I hope you guys don't mind if I ask an associated question. Some have warned about getting the tranny, driveshaft, and diff too well aligned. The inferance is that this would be disastrous? Can anybody shed any light on this? I'd love to learn what, if any, problems this would cause.

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Dan, I agree, it IS a Ron Tyler mount. His idea, AFAIK. I also agree that lowering the front of the diff is another great advantage!

 

The issue with getting it too well aligned is that if there is less than say 1 degree of total u-joint angle, the roller bearings can brinnel the u-joint cross surface. But don't worry, with a V8 old Z, you have lots of things working against you getting this low of a u-joint angle:

- short driveshaft (especially with a JTR position)

- the diff is offset so that the pinion is to the driver's side of the tunnel.

- if you do like JTR and move the engine to the passenger side, this and the above diff location issue makes a 1 degree or more u-joint angle in the horizontal plane.

- low engine location (JTR) usually means a low trans output shaft.

- high angle on diff (until you lower the front with a Ron Tyler or other custom mount, and/or raise the rear of the diff

 

My car, with the Ron Tyler mount, raised mustache bar (cut urethane top bushings) deletion of the JTR engine crossmember spacers, raising the tranny tail up as far as possible with the Tremec, all added up to a total of about a 1 degree vertical component for the u-joint angle, and about 3/4 degree for the horizontal component, giving a total u-joint angle of about 1-1/4 degrees. It'd be hard to get it much smaller than that!

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Guest Anonymous

Okay, I thought about it a little bit more. (You engineers may get a laugh out of this)

 

Is twisting along the X axis an issue? I think it's x, you know, rotation. If so, would fab'ing a shorter "Taylor" mount and using short urethane bushings stiffen things up a bit?

 

Also, I feel that just for safety sake there should be some support under the differential (use it to reduce further twisting too?). Maybe just a strap attached to the same mounting bolts would work here. Would that be too much stress on the frame attachment points? Would I EVER apply that much torque?

 

BTW, the same control arm attachments that are used in at the rear fit in the front so you could remove the crossmember and have a nice clean set-up.

 

On the other hand, would the "Scottie strap" (sounds funny, sorry Scottie) be just as effective a mount without all the extra fab'ing?

 

I haven't had any driveline alignment problems using the existing crossmember. And as an aside (just food for thought) a guy that preps early mustang race cars out here said you need some driveshaft angle or you'd get lots of vibration. Keep in mind a mustang drive shaft is much longer than a Z's.

 

I guess it's just personal preference really. And a ground clearance issue?

 

Either way, I'm not going to go through the trouble of building a pinion snubber.

 

I'm going to keep it simple.

 

Thanks Guys!

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Twisting about the pinion centerline is reacted by the mustache bar. The only loads the front of the diff see is the vertical reaction of the pinion on the diff case up front, pushing it up under acceleration. There's a bit of side to side, caused by u-joints or CV-joints being out of phase side to side (that could be handled by phasing them as you insert the side axles (u-joint halfshafts) or CV-shafts into the diff.

 

Something below the diff. Well, I just left the crossmember there, since I had modified it earlier for duals with clearance. But the diff front end gets pushed up usually and the only reason it'd get pushed down would be doing hard acceleration in reverse. The GM diff mount is interlocking and should be able to handle that.

 

The ground clearance issue is if you run dual exhaust or a 3" pip with the front diff crossmember, you have to run it low under that crossmember. If you removed the center, you could raise the exhuast.

 

Scottie's strap has metal to metal contact when the stock mount stretches under acceleration. I wanted rubber to be compressed above the diff nose, hence the Ron Tyler mount.

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Guest Anonymous

Agree totally with you Pete. And I am in no way challenging your design decision. smile.gif

 

The strap underneath the "Taylor" mount is in leiu of using a modified crossmember. It seemed to me as a simple way to achieve that. And like you, I know that a Hybrid Z is constantly metamorphising(SP), hence the modified mount you had to work with, others may not.

 

I do think it comes down to personal application/preference though.

 

With my install I use a single 3" under the crossmember. So I'm cool with the clearence I have. Esp with taller overall tires and wheels than I currently have, I should be fine.

 

What I'm going to do is actually a Hybrid design, that addresses the concerns you brought up.

 

And again, I thank everyones input and saving me from wasting my time on a less effective design.

 

Cheers.

 

Jon

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Jon, sorry if I came off sounding harsh or anything - I didn't mean to!

 

Just trying to explain what goes on down at the diff and the mount. Being a mechanical engineer makes me always analyze this stuff a bit deeply.

 

Yeah, I know all about metamorphizing. My car has seen many changes in design without turning a tire!

 

I'd love to see pics of what you come up with!

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