Hi,

I have 68 Delta 88 with 455 and TH400. The car has some very high gear rear axle since I only have less than 2000 RPM when driving about 60 mph. I think it could be somewhere around 2.5:1 or so. Do I have any other options to go a bit lower gear and get posi at the same? Currently I have open differantial and would like to update that also. I'm not looking anything close to 4 - just a bit lower than I have now.

-Sami

 

I have a '69 Delta with the 455 2bbl/TH400 combo. According to the original owner, he ordered the trailer tow package. The axle is a large 12 bolt with posi and 3.23 gears.

I would assume the same or similar was available in '68.

 

The 68 Delta 88 came standard with a 2:56 gear on AT cars. You can easily change this over to posi with the proper carrier and keep the same ratio or you can change to a lower gear. Were you looking to change to something like a 2:73 or 3:08? You just need to get the right carrier.

Can I suggest you get in touch with Jim Mitchske (monzaz) or Brian Trick (507OLDS) on this site? They both build and sell what you're looking for.

 

I can check the shelf for a posi BUT ratios and rears are getting VERY hard to find as all the demo derby guys have KILLED these cars and rears....

I am expecting a few coming in with in a WEEK will see what ewe get and the prices I have to pay. Jim Mitschke - J D Race

I do have a 1965-1970 Full size rear that will fit your 1968 Olds with 3.55 gears

Posi New 3.55 gears 12 bolt ring and pinion Full size Pontiac rear that was used in a slightly less powered Olds cars. This rear will more than do the job it has a 8.875 ring gear diameter BUT all the rest of the carrier bearings pinion shaft size are all the same size as the 9.3 you have under your car.

Pictures are of the actual rear...

REMEMBER you do not go by the cover bolt count to tell whether the ring gear is a 12 bolt bolt...A LOT of GM rears are weird like that...

 

Thanks a lot and yes - I'm looking something like a 3:08 or 3:23 with posi. I think that if I go lower than 3:23 I may have bit too high cruise rpm without overdrive. Another option could be the overdrive transmission but I have no experience about those so far but I may do some search. I personally like the idea but as I said I have no experience of it.

My car came with 455 2bbl HC - so I think it has this 2:56 gear. Now when I updated the engine with E-brock heads, Performer intake and cam I would like still to do some other changes just to make it even better


monzas: do you have above mentioned (3:08-3:23) gear ratio with posi? Complete rear axle is a pretty heavy thing in my case - since I should ship it to the other side of the world. I will discuss with my friend who is dealing with overseas shipping tomorrow - so I then I know what are my options.

And thanks for all the answers so far. It's great to see how easily I have found help from here.

-Sami

 

Jim, that is a sweet axle you have there! Looks like you blasted the whole thing/ painted it and installed new bushings too! Seeing it has 3:55s in it, I'm guessing it could easily handle the 3:08 or 3:23's Sami is looking for? I think the big problem you guys may run into if you can broker some kind of deal is the shipping to Finland.

 

Allan R: I know that there are several companies who are offering overseas shipping services. I'm also dealing with logistics (I'm teaching of it) and have helped few of those shipping companies because I have sea container handling facilities but I have not ordered anything from US so far. Anyway it should not be a big problem - I just have to consider what is the easiest way to get right parts here.

-Sami

 

Sami - If you do end up buying that axle from Jim I feel confident in saying you will get a quality built product. Jim sold me a series 3 posi (reconditioned) and I'm very happy with his price, shipping and quality of work. I know you'll work out the best logistics for whatever you end up buying.

 

Allan R. Thanks for recommendations, I'm sure that Jim is selling a quality product. For me it's even more important to trust a seller because of the high shipping costs (especially I have to be sure that I get the right product). This 3.55 is just maybe little too low for my current setup. I have still time to find it since the winter is just coming and the car will stay in the garage for the next few months.

-Sami

 

I understand. Have you considered discussing the option to change the gears from 3:55 to the 3:08 or 3:23 you want? I think the carrier used for the 3:55 is the same as the one for 3:08 and lower.

Another option may be to buy the carrier and gears from Jim and have them installed locally when they arrive? That would cut down tremendously on shipping cost. If you have the skills or know someone who has the skills to install and shim properly it may be a less costly workable solution.

 

Allan R: I will have to consider also the later option you discribed. I've got one shipping offer today that includes also tax and VAT which was close to 1500 $ (and that was rough estimate) + the price of rear axle itself.

I have done that installation job ones before succesfully but in this case I would prefer someone more skilled person with correct tools and who is doing that more regularly.

-Sami

 

I have owned numerous 1969 & 1970 Deltas & at the time was quite familiar with the avaialbe axle ratios. 2.56 were common & 2.93 gears were optional. I have never seen 3.23s in the 12 bolt...only on the older 10 bolts in the 67 model.

Are you sure that your car has 3.23 gears?...what is the axle code on the axle tube or have you had the cover off to verify the ratio?

Just an FYI you can get 3.07 gears for this big 12 bolt from any 71-73 Riv boat tail...find a Riv GS & you get 3.42 gears.

 

I have a 68 98 differential with 2.73 posi
Rusty from use in Michigan, not at all as pretty as the one seen above

BUT... I could extract the carrier and pinion and ship just those.

shipping would be much less for a small pkg like that of course. I recently shipped a pair of heads to England, the initial web site based e$timate was like $1000 the pair- thru discount at work via ups, the final actual cost was much lower.

 

Thanks for the offer Octania. I may consider that if I can't find anything closer to 3 within few weeks.

-Sami

 

I checked my rear axle today and it has 12 bolt cover and 12 bolt ring. Marks stamped the gear were 16B41 GM UH11 (so it's 2.56).

-Sami

 

Was moving the car around the other day so I jacked it up and found it has the stock 2.56 axle ratio. It's very torquey and feels lower (numerically) than that. So much for the owner remembering what he ordered lol. It is limited slip.

The car has the handling package option (front and rear sway bars with the boxed lower control arms on the rear). To bad the car is so rusty, would make a great driver. For now, I'll keep it intact and movable until I need or sell parts.

 

SAMI- Your going to have a heck of a time finding that ratio and that rear end. ALL full size cars are just tough rear ends to get parts for. EVEN here in the STATES. EPA and demo derby car r have taken many of these cars and destroyed them becoming import cars...lol

It is amazing that Fab craft even produced the 3.55 gear set for the Pontiac Full size 12 bolt rear 1965-1976 era span) with 10 bolt cover.... The ring is 8.875 same as GM A-body chevelle ring gear diameter BUT the pinion shaft is MUCH MUCH larger and 31 spline axles JUST like your 9.3 Olds Full size rear.

Finding 3.08 3.23 3.42 in these rears is VERY hard anymore. Posi units are even harder.... Plus there are no parts to rebuild your posi in the 9.3 either... At least the Pontiac uses a EATON posi and you can use 12 bolt chevy clutches to rebuild these posi units.

We can ship this rear to any port in the USA for a container shipping to your country. WE do this A LOT Sweden, Finland, Norway, Germany, France, UK, Australia. If you get on some of your countries car forums you might find some one with a container over here and pay for a spot on it it will be cheaper for you. Jim

 

Hi Monzaz. You didn't get the 2.93 gear set and posi unit we discussed about?

I have one friend who is going to ship 2 containers to Finland within the next few weeks. He is living in Grand Rapids MI - so that should not be a problem.

-Sami