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Old 10-19-2014, 03:52 PM   #1
TBone69
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Default Perch Bolt Diameter? Drop in or Press in?

Hey Folks,

Got some time in the garage today and working on reassembling the front axle and wishbone. I have two used perch bolts that are in good shape or seem to be but one drops right in to the axle the other seems like it needs to be press fit.

Drop in Perch Bolt diameter measures out at .667 and the one that needs some coaxing to get in measures in at .682.

This is my first time reassembling an A front end which one is correct?

I have a feeling its the one that needs pressing in which means I will need another perch bolt.

Thanks
Tom
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Old 10-19-2014, 06:30 PM   #2
H. L. Chauvin
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Default Re: Perch Bolt Diameter? Drop in or Press in?

Old Model A perch bolts that have been installed for a long period can be almost impossible to remove.

For removal, many resorted to heating same & hammering them out which tends to make the diameter fatter mostly on the threaded end.

Appears one is .015" larger than the other, so .007" would have to be removed from the outer surface to make them equal -- could one be slightly oval in lieu of round and/or, are there any burrs in the hole or on the bolt?

This may not make a difference, but always worth a try; e.g., did you try to swap perch bolts from L to R or R to L ?

If it were mine, I would polish the hole & the bolt with plumber's sandpaper & try it again & investigate if any irregularities -- if need be, remove metal with a flat file -- once installed properly it will not move.
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Old 10-19-2014, 07:10 PM   #3
Joe K
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Default Re: Perch Bolt Diameter? Drop in or Press in?

It has been my experience that Perch typically are "pressed in" so your hard to fit one is probably closest to original.

Not to say that the lesser diameter one will not fit directly. IIRC, the perch emulates a cone at the top (below the spring and contacts the upper radius rod yoke) and the nut at the bottom is a virtually identical situation with the cone part being machined on the nut.



Thus when both perch and nut are in place, the perch is held as tightly as it ever will be.

I would use it.

I certainly would look at the bolt diameter charts and do a torque on this equivalent to a SAE 5 bolt. I would like to say a SAE 8 bolt, but VERY few commercially available fasteners rate at SAE 8 unless they're specifically qualified - and repeatedly tested for maintenance of quality during manufacture. The Model A spring perches are no where near this well made methinks.

Nor is it really necessary?

Looks like a 5/8" nut on that so torque will want to be perhaps 150 ft-lbs?

See http://www.engineershandbook.com/Tables/torque.htm

Joe K
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Old 10-20-2014, 08:16 AM   #4
Terry,NJ
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Default Re: Perch Bolt Diameter? Drop in or Press in?

On both my cars, both bolts came out and went back in with no problems. Just to be sure, for future removal, I liberally coated the shank/body of the bolts with Neverseize. The thread is 5/8-18. This bolt and nut are Coned/tapered so if you don't have a lathe, a common nut will not do the job. Try Trans-bearing, in Asbury Park (If their still there, It's been a while)
Terry
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Old 10-26-2014, 08:20 AM   #5
BigEd
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Default Re: Perch Bolt Diameter? Drop in or Press in?

TransBearing
1771 New Jersey 34 #4, Wall Township, NJ 07719

(732) 681-8600
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Old 10-26-2014, 11:56 AM   #6
Ulysses6
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Default Re: Perch Bolt Diameter? Drop in or Press in?

Quote:
Originally Posted by BigEd View Post
TransBearing
1771 New Jersey 34 #4, Wall Township, NJ 07719

(732) 681-8600
http://www.transbearing.net/
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Old 10-26-2014, 04:57 PM   #7
Terry,NJ
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Default Re: Perch Bolt Diameter? Drop in or Press in?

Quote:
Originally Posted by Ulysses6 View Post
I once needed a bearing for my John Deere Combine. J.D.'s price was over $10, Transbearing's was $1.50. Same bearing only with out J.D.'s markup. It's a good idea to always check the bearing houses.
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