According to my calculations my 70 GS has the counter option 4.30:1 gears, my tires are 26.5", my car is factory manual 4speed with open rear but at 50mph the engine is revving at 2800 RPM, I've double checked with GPS speedo and aftermarket tachometer. I know at 2800 RPM there's nothing hurting engine but is too uncomfortable hearing it screaming at such slow speed, the performance is great but at this moment this car is my daily driver and this kind of gears isn't helping with fuel economy or even with driving comfort, also the rear end feels so high that doesn't matters if I kick off in 2nd and then shift to 4 or do the complete 1-2-3-4 the performance feels the same which feels like some kind of way of wasting the car performance I've read that Buick and Chevy rear ends can't interchange ring and pinions but is this the case for a 70 8.2 rear ? According to my calculations I could be really happy with 3.23s gears, I know kick off will be slower than with my current 4.30s but I really don't care, I don't have the car for racing, I just enjoy driving a rare car but want to be able to feel the power of the 455 at WOT
There arent many gears available for the 70 8.2, closest you'll get is a 3.42 gear from TA Performance (which is a really good match for a BBB , BTW).
It would be odd to have 4.30 ratio gears with an open carrier. I would love to see a picture of the numbers on the side of the ring gear. Another possibly, is the presence of a damaged posi carrier. Have you taken off the cover to check for metal debris? Fabcraft Metalworks is the only company making Buick only 68-70 8.2 gear sets: http://fabcraftmetalworks.com/ The only ratios reproduced are 3.42 and 3.64. (Fabcraft is gearing up for another production run.) BOP or Chevy 8.2 gears and carriers do not interchange. You can purchase used 3.23 gears on this Board but there may be a question mark about the condition of what you are getting. If you do have a set of 4:30 gears, somebody on this Board will buy them. They are not good for street use.
I know is a open rear because I already changed the oil and gasket (was one of the first things I did when got the car running) and there was no posi there but I never inspected teeth numbers or stamped numbers but according to my calculations of RPM, Speed and tire size it is a 4.30:1 rear. I'm planning to check today the tires rpm vs driveshaft rpm just to be sure I saw it but $550 bucks for ring and pinions seems to be like a really high price for a street application
I want to keep my buick all buick but I have some idea flying around in my head. Is it too complicated to swap the buick 8.2 to a Chevy 8.2 ? What could be the pros and cons? what needs to be considered when choosing the new rear?
The Buick 8.2 is a much better rear than the Chevy 8.2. The Chevy rear is a C clip rear, while the Buick is a bolt in axle rear. Your best bet is to find a 1971-2 Buick or Olds 8.5 10 bolt. That rear came in the Skylark/GS and Cutlass in 71 and 72. Parts are easily available as GM used it into the 1990's. It is also bolt in axle and has strength that rivals a 12 bolt. I have an 8.5 in my car out of a 1971 GS350. I upgraded it with 30 spline Moser axles and matching Eaton Posi carrier. I'm using Yukon 3.73 gears and it has been very durable. A 3.42 gear set with 28" tires will be like a 3.24 ratio.
http://jdrace.com/diff_id/10b82chevy.htm http://jdrace.com/diff_id/10bBOP_Buick.htm http://jdrace.com/diff_id/10b85.htm
Not sure if TA Performance might have some gear sets? Fabcraft also had a Posi Carrier, probably the same one in the TA catalog.
why not? I think 70 monte carlo uses the 8.2 10 bolt and brake to brake length looks like the same of my Buick With just a quick search I found this chevy 10 bolt for just $150 (I think is a chevy but is the first time I saw one with that cap), I'm waiting for seller measures Does Chevy and BOP uses the same wheel bolt pattern? Buick, Pontiac and Oldsmobile parts are some kind of hard to find in my country so my best bet are Chevy parts, I'm going to give a try with Buick parts just to see if I can find something Just a quick question that came to my mind: Any BOP gear will work on a Buick rear? for example gears out of an Oldsmobile will work on my BOP 8.2?
If you are talking about transplanting the entire rear, then yes, 64-72 GM A body rears will interchange. There are differences in overall width, but it's minimal. U-joints are different, but you can use a conversion u joint. I'll repeat, the Chevy is actually an 8.125, and it is not as durable as the Buick 8.2. Yes, wheel bolt pattern is the same for A bodies, 5 X 4 3/4 bolt circle. No, the 64-67 BOP 8.2 rears are NOT the same. The 68-70 8.2 Buick rear is different than the other 8.2 BOP rears. People have been making that mistake for many years. You are more informed.
Drum to drum may be made to work. I thought you were considering using the 8.2 Chevy carrier in the Buick housing.
The Buick 8.2” is a stronger rear,compared to the Chevy 8.2”. I would build that OR get a 71-72 8.5” 10-bolt,and build that.
I just took the time to remove rear cap and check tooth numbers, the ring tooth quantity is 41 and pinion is 12 which gave me a 3.42 rear end, I double checked numbers and also verified part numbers. Looks like my calculation were bad but now I'm a bit more confused because according to this calculator at 50 mph I should be doing 2200 RPM instead of my current 2800 RPM, so, what could be the reason? Gears numbers: Could be possible that somebody messed the transmission gear ratios? is the unique idea that I have in mind to explain the additional 600 RPM I'm located in Colombia, South America
Perhaps your tach is off? Another possibility is the use if an improper gear speed reduction device on the driver's side of the transmission. Does the speedometer cable screw directly into the side of the transmission or does it screw into an odd looking gear ratio reducer which is mounted on the transmission?
Does the cable screw directly into the transmission,or does it screw into this piece that is pictured?
Thanks Brian. There is nothing like a picture. My thinking is that someone changed has rear gear from a higher ratio to 3.42 and mistakenly left the speedo gear ratio adapter in place.
