frame drilling

[JD160]

I'm replacing the inner frame rail in my 86 superliner w 44 rears.  Im having a hard time finding info on drill and ream sizes.  Mack is sending me 20 mm trunion bolts and chart says to make hole 22 mm

I have mag drill and need to order drill and ream

any help and recommendations would be great

P G Adams is bending the frame but lead time and cost is the reason I'm doing holes

[j hancock]

Body bound trunnion bolts use an interference fit so the hole needs to be SMALLER than than the shank dimension.

 

[Rob]

I had a local machine shop grind annular cutters the right dimension for these although I started purchasing fasteners and hardware at Mcmaster-Carr which worked very well. Use grade eight, or nine and get them tight. I always used nylocks and hardened washers with the bolts being flange head. Lot of trucks running around this area without problems using this method.

[Freightrain]

That chart looks to make everything .002-.005 press fit for the shank of bolt.  I suppose if the shank is about the same size UNDER then it would slide in.  If not, it would take a really big hammer to seat them?

When I did my air ride stretch, I used Gr 8 5/8" flange bolts, self locking flange nuts and reamed the holes to 5/8".  Put them down with my 3/4" impact.

[Rob]

PG Adams did the rails and I laid out the holes using Mcmaster fasteners on my 57 B-61. Used my Hougen 505 magdrill to punch them through. Very accurate as all holes vary less than 1mm distant from side to side.

 

 

 

 

 

 

 

 

Edited April 9, 2018 by Rob
Photo Space

[JD160]

Thanks guys

 

thats the chart I needed

 

nice pictures

nice people at Adams

[Rob]

When I ordered my rails, (80ksi steel) they sent a dimension diagram to fill out. The final product is well within 1/16" of those dimensions meaning the new rails were as close as you were going to get to perfect. The factory frame rails varied is size about 1/16", (height) and that dimension was replicated in the replacements as the new rails slipped over the originals after being cut off. The PG Adams rails fit like a good pair or gloves as can be seen here:

 

 

 

 

 

 

I found PG Adams to be more expensive than other vendors but I'm happy with the product and am certain you will be too.

Then I lost my marbles and don't know how to do this kind of crap anymore.....

Rob

 

Edited April 9, 2018 by Rob
Photo Space

[j hancock]

I got the rails for the B75 from PG Adams plain.  Used body bound bolts only at the trunnion and the air gun pulled them into the undersized holes without a problem.  5/8" flange nuts and bolts used for everything else.  With a stretch and needing room for outboard cylinders, everything was mocked up before drilling holes.