I have one final set left till we hit the swap meets again.
3.42 GM gears
no issues
clean and quiet gears

85.00
plus 12.50 shipping

Jim
J D Race
330 990 8155

 

Do you know if these will fit my 1969 Cutlass 10 Bolt Posi rear-end?
Thanks, Alex

 

Alex, they will fit.
Check the title of the thread - specifically says 8.5 10 bolt. Doesn't matter if it's posi or open carrier - they'll fit.

 

Thanks Allen, always glad to get a helping word from you. I'm still unsure of my Gear Ratio and need to figure that out soon.

 

Allan R wrote...

Alex, they will fit.
Check the title of the thread - specifically says 8.5 10 bolt. Doesn't matter if it's posi or open carrier - they'll fit.

No or Maybe is actually the correct answer


You need to know what rear end is in your car FIRST. You car did not leave the factory with a 10 bolt rear end. What is in there now. If you have a 1971-72 8.5" 10 bolt in your car now then yes. Any other answer then no.

 

Dave??
Check Alex's question. He said clearly he has a 10 bolt rear. That's what I based my response on.

 

And does it state wether or not it is an 8.5" 10 bolt or an 8.2" 10 bolt? Because if he has an 8.2" 10 bolt from a Chevy or a Poncho or a Buick then these gears will NOT fit.

 

You're welcome. But Dave brings up an interesting point (below). Is your car's rear end the original one or not? When you said it has a 10 bolt, I made the assumption you had swapped it out since US produced 69's didn't come with 10 bolt rears. Let's back up a step - how did you determine it was a 10 bolt to start with?

You mentioned one time you needed to determine what gears were in the diff? Did you resolve that yet; and is that why you're looking at these 3.42's?

Good point. I didn't think of that. Guess we'll have to wait and see his response.

 

Well I just called the previous owner(my uncle), when he bought the car in 1989 it came with the current 10 bolt, posi rear-end. It was a family car before that and he isn't sure about the first owner. I was unaware that 10 bolts didn't come on the 69'. This is the first Im getting into my rear-end so sorry for some of the unknown answers. Im also at University right now so it can be a little difficult for me to get answers right away.

 

Alan Oldsmobile's did have 10 bolt rear ends they do come with a 12 bolt cover however when people talk 10 or 12 bolt I believe they are talking number of bolts on the ring not the cover. Canadian cars I also believe got Chevy differentials which also came in 10 and 12 bolt but pretty sure a body's would have gotten the 12 bolt, but I could ( and am probably ) wrong lol...

Just adding to the confusion, I will give Monzaz a 5 star seller rating however , I would deal with him anytime and his word is his bond

Someone will clear this up I am sure

 

Alan wanted to say in 1968 and 1969 they had 10 bolt rears with 12 bolt covers. I also think if the rear is original as said maybe it is an 8.2 ring? I Think, not saying for sure

 

My Rear-end has 10 bolts around the rear diff.

 

I think we know it's not the original rear end, so I'll wait a bit to see what happens. Usually when people say they have a 10 bolt they do that because they only see 10 bolt covers. I know that's not the right way to identify it though. In your case it only has 10 cover bolts so it's likely not the original rear end. Could very well be a 10 bolt 8.5" corporate GM.

Alex, maybe your uncle can snap a picture of the rear end and send it to you for posting here. Jim (monzaz) will be able to identify it likely by its existing cover (if it's the original cover). Other than that I think the only way to identify the differential is by shape or possibly foundry casting marks.

 

Hey Allan, Ill have my brother get a picture of it tomorrow and post it here. My uncle was just the owner before me and owned it for 20 years before I bought it off him in 2010. Hopefully I can find out what ive got on my hands.

 

This really went nuts.... Just post the pictures and will ID the rear Make sure you give enough other surrounding casting also to ID he rear. Jim

 

So, we have various 10-bolt ten bolts,
"the" 12-bolt twelve bolt, and
the '67-70? Olds 10-bolt twelve bolt

does that sum it up?
Clear as mud?
Can we PLEASE get a rear ends 101 sticky with photos?

 

I would be interested in purchasing these gears, but I have a question.
Will I have to change to a posi carrier or can I keep the same one I'm using now with the 2.73 open?

 

PM sent.

 

The gears will work with either an open or a limited slip carrier but what is the point of changing gears & not installing a posi?

 

Wouldn't changing from a 2.73 to 3.42 also require changing from a series 2 carrier to a series 3?

 

I was just curious. Posi carriers are expensive and I'm dying to wrench on something.

 

No. Not on an 8.5" carrier.

 

I purchased the whole deal posi , gears, bearings seals through monzaz (Jim) plus shipped to Canada US dollars etc, Jim has an awesome price, not that expensive at all. I'd say go for it and do some wrenchin!!!

 

Ditto. I did the same thing for my type O 12 bolt (less the gears). Randy (RROLDSX) did the same thing for the original 3.07 geared open Chevy 12 bolt in the Canadian 1969 442 that I sold him. I think Allan R did same for his 8.5" in his 72 Olds.


Highly recommended.

 

Roger (scooter) as well, Were going to have to ask Jim if he's selling shares into JD race lol.

 

I already had a set of 3.23 and 3.42's. Jim provided me with the posi carrier. His price was very fair on purchase/service and shipping. I had good conversations with him and recommend him to anyone.

 

Hi Allen.


What size rear gears are you running in your 442, and do you still have the factory automatic or stick? Just curious, as my brother's '71 442 had 3.42 gears from the factory, but contemplating on going with a 3.08 or 2.73, while keeping the factory TH-400, to keep the rpm's down. I think there will be enough torque even with the higher gears to be happy around town. When the car was running, even with the wider G-60 tires at the time, it was hard to keep the tires from spinning with the 3.42 gears.


Anthony

 

Leave the gears alone & put a 275 60 15 (28") tire out back. You will hate the performance with 2.73s. 3.23ss are not enough of a change to warrant the expense. changing to 3.08s is way more money than a tire size change. The tall tire wont get you all the rpm reduction but it will certainly help.

 

Thank you Dave for the suggestion. Unfortunately, the 3.42 equipped rear axle was stolen while in storage, so we are open to any size gears at this time. There is an 3.08 posi rear axle available, as well as a 2.73 posi. Going to an overdrive automatic transmission with 3.42 or 3.73 gears was also an option, but still leaning towards keeping the TH400 with the lower numerical gears. Will the 2.75 tires fit on 7" wide rims, or do you need to go with 8" rims? Those will surely help keep the rpm's down, as well as filling up the wheel wells.

 

Anthony, my car is actually a Cutlass S, not 442. But to answer your questions I now have 3.42 gears with a limited slip carrier that monzaz sold me. The car is a factory automatic and I plan to leave it that way. Tire size is 225/70/14.

Dave makes a valid point for anyone not wanting to spend a lot of $$ on gear swaps. I thought of that too at one point but elected instead to change from a 2.73 (SA code axle) to 3.42

 

Gear swap is really a each to their own deal. What works for one does not work for another. One guy may not have a problem with 2500 -3000 rpm while another will hate it. The only way you can sell someone on a gear is to match it to the camshaft and engine requirement for all out full throttle power like drag racing etc. Everything else is really what the customer wants the car to do. Biggest problem I run into is when people pick too big a cam for the car and then they have no low end and expect because they picked a 400 Horse Power motor that torque comes with that combo just the same...WHICH it does, BUT it all moves up in the power band and RPMs to get it. So it is a band aid for a bad cam pick.

IE (CAM 1) 400HP 230 duration at .050 at 6000 rpm and 400 Ftlbs at 4000 rpm
picking less (cam 2) HP like 350HP 212 duration at .050 the torque may stay close to the same 375 ft lbs. but in at 2500 RPM s which is in a better more usable range

So cam 1 will start making usable torque at 2000 RPM like 200 ft lbs. and go to 5000 before falling off... cam 2 will start at 1000 RPM 200ft lbs. and fall off after 4500 RPM hitting 375 foot lbs.

Now remember that compression, Head size Manifold volume valve size and carb size will ALL affect the motors ability to Build torque and horse power and how fast it comes in.

You can see that cam one will be way better for the track and lazy with out a 2500 stall and gear to get out of the hole snappy where as the cam 2 will be great with stock and even benefit from a convertor carb and intake but still give gobs of FUN tire spinning low end torque and passing fun on the freeway. In the case of cams slightly smaller is better than a big fat harry cam. Period. This is why TONS of stock factory cammed cars ended up rapped around trees and ditches etc. Crazy quick torque.

Wow where did I go with all that...

Find out what you want the car to do for YOU and know what is in your engine so you can pick the correct parts to put that smile on your face ... as that is the true test of the whole deal of Muscle cars... FUN

Jim
J D

 

12 bolt chevy 65-72 has 12 bolt cover and 12 bolt ring gear bolts 8.875 diameter c-clip axles 30 spline (RIGHT PICTURE)
12 bolt olds late 67-70 has 12 bolt round cover smooth and 10 bolt ring gear 8.4/8.5 diameter Bolt in Axles 28 and 31 spline (67 68 w30) axles (LEFT PICTURE)
10 bolt olds 64-67 10 bolt scalloped cover and 10 bolt ring gear 8.25 diameter bolt in axles 28 spline (MIDDLE PICTURE)

If you check out the web site jdrace I have all this info and more under ID differentials button tag on the left screen... pictures, bearing part numbers, carrier breaks, everything for most all GM rears. Jim

www.jdrace.com

 

Thanks Allen for the information. I saw the photo and thought you had a 442. Does your Cutlass have a 350 or 455? I would think the 350 could use the extra gearing due to the lower torque for around town driving, compared to the 455. During the day, the 3.42 gears were the perfect compromise for most cars that needed to be driven daily to work and the occasional traffic light challenge. Everyone has excellent points and advise regarding this subject.

 

Thank you Jim for all of the information. The '71 442 automatic will be completely stock, which will have a low torque peak as you described. This is why we are thinking the 3.08 gears should be adequate and a good compromise. Unless we can find a set of 15" bolt-on SS-II rims, we'll be sticking with the 14" rims.


Back in the day, the 3.42 gears were considered on the low side (numerically). Besides the now a day mileage concerns, the higher rpms give you that "where is the next gear" feeling, especially with the new cars just loafing at highway speeds. Even with the 3.23 gears in my friend's A/C equipped 442, it also has that "when are you going to shift" feeling when on the highway.


But like you said, it is what the individual is looking for, wants, or needs.


QUOTE=monzaz;660300]Gear swap is really a each to their own deal. What works for one does not work for another. One guy may not have a problem with 2500 -3000 rpm while another will hate it. The only way you can sell someone on a gear is to match it to the camshaft and engine requirement for all out full throttle power like drag racing etc. Everything else is really what the customer wants the car to do. Biggest problem I run into is when people pick too big a cam for the car and then they have no low end and expect because they picked a 400 Horse Power motor that torque comes with that combo just the same...WHICH it does, BUT it all moves up in the power band and RPMs to get it. So it is a band aid for a bad cam pick.

IE (CAM 1) 400HP 230 duration at .050 at 6000 rpm and 400 Ftlbs at 4000 rpm
picking less (cam 2) HP like 350HP 212 duration at .050 the torque may stay close to the same 375 ft lbs. but in at 2500 RPM s which is in a better more usable range

So cam 1 will start making usable torque at 2000 RPM like 200 ft lbs. and go to 5000 before falling off... cam 2 will start at 1000 RPM 200ft lbs. and fall off after 4500 RPM hitting 375 foot lbs.

Now remember that compression, Head size Manifold volume valve size and carb size will ALL affect the motors ability to Build torque and horse power and how fast it comes in.

You can see that cam one will be way better for the track and lazy with out a 2500 stall and gear to get out of the hole snappy where as the cam 2 will be great with stock and even benefit from a convertor carb and intake but still give gobs of FUN tire spinning low end torque and passing fun on the freeway. In the case of cams slightly smaller is better than a big fat harry cam. Period. This is why TONS of stock factory cammed cars ended up rapped around trees and ditches etc. Crazy quick torque.

Wow where did I go with all that...

Find out what you want the car to do for YOU and know what is in your engine so you can pick the correct parts to put that smile on your face ... as that is the true test of the whole deal of Muscle cars... FUN

Jim
J D[/QUOTE]

 

www.jdrace.com

ID differential section

 

Ive got a 672 posi (low series for Type O for sale. Also a 4.66 r&p .
$450 for posi
$250 for 4.66
Plus freight.
PM if interested. Pix avail