I have a street rod 32 Ford frame that has an aftermarket 9" housing with no center section. The axles are in it -- what is the best way to count the splines to determine what center section to buy? Also, there is no drain/fill plug in the housing, does the center section have a plug to drain and fill the lubricant? If not, how and where do I install one? Thanks, Jim
Well you either take your marker and mark a spline and slowly rotate the shaft while you count splines or you pop the axle out and stand it up and mark a spline and count your way around. I don't have a small bearing axle to look at but 28 spline axles usually have the small bearing while 31 spline axles have the larger bearing and larger bolt pattern and bolts and nuts. As far as fill plug, just make sure that the third member you get does have the fill plug in the side. The fill plug should be on the left (US drivers ) side of the third member. My photo didn't come out when I went outside and took one a minute ago.
Thanks for the help. It has a 5 on 4 1/2 bolt pattern. I've never replaced a 9" center section, so I didn't know if the fill /drain was in it. Thanks, Jim
Your kidding, just count the splines. 90% chance they're either 28 or 31. All of the 9 inch rears I used in my customer ch***is for the last at least 10 years were 31 spline. Most of the gear centers being sold today have a fill plug on the left side. Double check that. Don't worry about a drain plug, if you need to take it out after use for some reason all you have to do is remove the nuts, put a drain pan underneath, use a large screwdriver and crack the seal at the bottom, it will drain 95% of the grease.
The man that built the frame couldn't remember for sure, but thought it's a 28 spline, and with axles in the housing it's hard to count the splines. I'm going to take the car off the ramps, and move my small lift over and get it under this car so I can get the axles out and know for sure what they are. Thanks again, Jim
I thought you might get a little flak about the count thing! Lol, figured you couldn't get under the car. Let me say this about the drain - Yes, the oil will mostly drain out when the center section is popped loose. Messily. Then when you fully extract it, there is still some oil in the bottom of the housing, more will drip out then. Afterwards, the remaining 1/4 cup or so of oil in the bottom must be mopped out with paper towels. This is where the finest particles of metal from wear will be. And you don't want them in there! An drain plug in the bottom of your housing is best. I swap between street and track pumpkins in mine and am installing a drain plug this season to eliminate the P.I.A. factor of my ''pseudo quick change''.
Original 31 spline axles have 2 holes in the end. Of the axle (wheel flange side), 28s have an odd shaped hole same location. Ki da like a circle with flat top n bottom if that makes any sense. Don't have a 28 to post pic
I take a paint marker and touch each spline while counting. That way you know you get them all, if it had a dot on it you counted it.
Most 9", but not all, center sections have a fill plug to get the correct lube level. Some 9" housings have a drain plug on the bottom of the housing. If your housing does not have a drain plug, add one now while it's oil free.
Be aware that there is a Lincoln center section that has 9 3/8 " gears and will fit your housing. They usually have a very high ratio like 2:70 for highway speeds. You can't get other ratios for them. You don't want to buy one of those by mistake. You can identify them by the ridge going across the top front and then turning down. The next thing to know is what you plan to do with the car. The engine/trans in it and how you plan to use them will determine if you need positraction and what gear ratio to get.
If you are not familiar with 9" stuff, the easiest way is, to take a dial caliper and measure the diameter at the splines. 28 spline will measure 1.184", 31 measures 1.335".
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