hi all. maybe that's a stupid question: can i upgrade my standard rear differential of my 65 riviera (TH400) in a simple way to a desired limited slip differentail (like on the GS)? i really have no experience on differentials and i need to know if i need a complete new diff or if i only need to buy a special spool. please name sources for the needed parts. i do not desire to have to have both axles locked/blocked.
The 64 and 65 Rivs. used a stand alone diff. for those years. there is a posi version. it is easy to change out, [if you are built like a 500 lb. gorrilla.] these are the 3rd. member type. They are strong. If you are lucky you can find a 3.42 but most are 3.08. There is a code at the bottom of the 3rd member housing. X in a circle denotes a posi. The numbers on the other side of the housing tel the ratio. [08 would be a 308- 42 would be a 3.42 ect.] The axels are the 31 spline type, strong.
Nim- Let me start by saying I am not "dissing" you just trying to teach. Your TH400 is your transmission. The rear in your Riviera is a 9 3/4. Very heavyduty rear. On the www.teambuick.com site there is someone selling a 3.08 posi unit. Looks very good check it out. Now back to your car's rear. Lift both rear tires off the ground (use Jack stands for safety-please). With the car in Neutral turn one of the tires-if the other tire spins in the same diection you have a posi (which you most likely do). To figure out your ratio without decoding the numbers. Place a piece of masking tape on the tire at the 12 o'clock position in the wheel well. Place another piece of tape on the drive shaft facing you. Slowly turn the wheel and note how many times the drive shaft spins for 1 revolution of the tire. Let's say it went around 3 times and a little past - you have 3.08 gears. 3 times and a 1/4 more turn- 3.23 3 times and almost 1/2 way around- 3.42. Good luck (I hope you have a posi!):TU:
Well, Yesterday I typed up a bunch of crap on this post and then lost it. So I try again. With the third member diff there is a set of markings stamped into the bottom of the third member case that tells if it is a posi , and the gear ratio without doing any thing else. Should be on the flange that mates up to the housing but may be else where on the bottom of the case. An X in a circle says posi. and the last two digits of the gear ratio is stamped on the other side. [ 08- is a 3.08 gear, 42 is a 3.42 ect.] just take a wire brush and clean the bottom of the case good and look with a flash light , real close , because some times the markings are faint.
thanks for the info - much appreciated. i will check today in my restoration garage the tire rotation "behaviour". i remember that in some of my books / magazines there was stated that you could get a real performance focussed (distributing same power to both tires) limited slip only with the "real" GS. maybe i did overread the note that you have also on the standard rivi a limited slip. my intention was to loose not any power when accellerating but to be able to still drive smoothly through curves and thight bends (like usual here in wuppertal / germany and the surrounding country). and no harm done ... i can't be dissed because i know i have still a lot to learn on my rivi.:TU: especially when talking about "optimizing" the reliable and bulletproof NH powerplant BTW i received new exhaust headers (from sandersonheader.com) and i am 1 step nearer to post pictures of the location of the H-pipe on my 65 rivi.
sorry for posting this "gear and drivetrain" question in the NH forum section. in the meantime i found out that my rivi has NO posi rear diff ... so i have to buy one to distribute power to both wheels in a "good" manner :3gears:
:TU: Good posting. Good stuff. Wilfred-Did you buy the whole rear end? I mean, somebody correct me if I am wrong, but you can simply swap third members. Correct? Is there any other difference in the axle shaft housing from a posi to open? I am very much looking forward to the pictures of your project Wilfred- especialy the Sanderson Headders. :kodak: Keep it up!:TU: Erik
One of the ways to tell a "posi" from a non-posi is the oil fill plug. The posi has a tag on it, but most importantly the fill plug is a 3/4" square fill plug instead of the usual 3/8" drive type plug. The ratio is on the very bottom of the center of the housing itself. 07 would be 3.07 (very common with TH400) 23 for 3.23 (very common with DynaFlow) 42 for 3.42, etc. all the way up to 4.45.
hi erik. i am not wilfred ... i am dirk. i bought the whole rear end from wilfred including lots of new spare parts like 2 (or 3) rear brakes including 1 set of drums ... for just 300! buying things from you guys here in the forum is much better than evil-bay because of the eye-to-eye techtalk. i think the metal tab on the oil screw is not a save bet because you can buy those things on ebay separately. you have to look at the parts. from the first glimpse the LSD is easely interchangeable with parts from my standard rear diff. unfortunately due to vacation my restoration guy has closed his garage until end of november so posting of pics will take quite a while (also of the H-pipe combination with the sanderson headers). regards, dirk (i am not wilfred )
My BAD Dirk! I misunderstood. I hope you will forgive me. I see you have now added your signature to the bottom of your posts. Erik
Yes, 4.45 gearing was last available in a towing package in 1964. It was a common ratio back in the late 30's & 40's. I have 2 sets, 1 used & 1 new I purchased in '68.
