General Discussion     Tech Questions     Parts & Services     Suggestions/Ideas     Help & Website Instructions     Blogs    

Spicer 8251 5 speed OD.
Print Topic | Close Window

By 1964 pete 281 - Friday, February 22, 2019 1:26 PM
Pleasure to be here, used the AHTS magazine subscription to rebuild my 1964 model 281 Peterbilt ( 114 BBC). From 2006 finished 2013. I wish I would have been aware of the forum.
I will try and be brief. I have a silver 8V 92 for power as the original 8V71 proved to costly to rebuild. The 92 came with a double overdrive 13 speed.
Passing of time and caretaker duties have ended my trucking options , not to mention calif EPA.
I would like to remove the 13 speed and replace it with the original 8251 and 8031G aux.
I plan on someday just visiting local truck shows and reminiscing for old time sake.
Obvious problem is the torque capacity differences between the 8V71 and the 8V92.
I don't plan on hauling and have always been careful operator.
I will attempt to increase the main shaft diameter of the 8251 from 1 3/4 to the 2inch ( find or make) So as to make installation as simple as possible.
Would an occasional haul be acceptable with this configuration ?
Any thoughts on this matter would be appreciated.
Thank you.
By Wolfcreek_Steve - Saturday, February 23, 2019 5:03 AM
Transmissions are all about how you use your right foot and if you are never loaded, tires will slip before gears break.
By Geoff Weeks - Saturday, February 23, 2019 2:15 PM
If you are going that route, just use a 1 3/4" clutch. you aren't going to make the trans any stronger by makeing a 2" input shaft.
I pulled 170K thru a 1100 series Fuller and a 14" organic clutch, its all in how easy you are on it.
where torque matters is all in the reduction gearing which takes place after the input shaft.
By 1964 pete 281 - Saturday, February 23, 2019 4:34 PM
Thank you for the responses.
I have been looking for the service manuals to rebuild that Spicer 8251.
Looks like a dead end, hard to believe as I have usually been successful in locating service manuals.

Hope to post a few pictures once I get it out of the barn by late spring.

Interesting off topic note.
Received the build sheet from AHTS a couple of years ago, truck was built for A&E ready mix in Arcata calif. That is the town I was born in four years earlier.
I was able to find and contact the original owner this past year, sent him some pictures. Truck was used on flat trailers hauling concrete products, he remembered it well.
Currently making a simple door sign reflecting the original owners the truck was built for.

It had the updated 8V71 Water above port? not the original air above port version ( large breather covers) It also had the Spicer 8055 as original equipment. The aux is still the original 8031G as listed in the build sheet.

By junkmandan - Sunday, February 24, 2019 3:26 PM
64 PETEY-------As an ex DDA sales rep '72-'86, i recall the water below port blocks came in chassis right around the '63 era. I was employed by Gateway Transportation starting in mid 60 through 1970 and we found sometimes even on 1st overhaul on a group of 6V71s in Crackerboxes, that we'd have to bore the block because of core shift due to lack of cooling .Our next purchase of 2 axle tractors gave us DCO 405 Internatioinals with the updated blocks that probably were from '62-'63 era, and I don't recall premature or unusual failures with these units.