1967 GTO rear gearing help.

Questions about all other brand differentials.
Valsmere
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1967 GTO rear gearing help.

Postby Valsmere » Fri Mar 07, 2008 8:47 pm

Hey everyone I hope you guys can help with a little problem I have. I have a 1967 GTO with the original YS code 335 hp 400 cubic inch engine. The trans is a TH400 that is not stock, as per the trim tag on the passenger side its a 1969 Buick unit. The rear according to the axel tube code,YD, is a 2.93 unit that came with the car because of the auto trans and the factory ac. I am planning on replacing the trans and pulling out the ac. The trans will be replaced with a Tremec TKO-500 or TKO-600 I haven't decieded which one yet. I know that I really need to change the rear gearing in the car to take advantage of the new transmission. I am planning on going from the stock 2.93 up to a 3.73, 3.90, or even a 4.10. My question is can I simply replace the gears or do I have to replace the whole carrier and axel? I have found that I can redo the whole rear axel assembly right down to disc brakes, and rears for around $2700, I'm looking for other options. I hope you guys can help and any information or ideas will be greatly appreciated. Thanks in advance for any and all help.

Valsmere

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monzaz
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Location: RICHFIELD, OH

Re: 1967 GTO rear gearing help.

Postby monzaz » Mon Mar 10, 2008 4:28 pm

Hi Valsmere, Yes you can use the same housing and change the gears... The carrier will either need to be upgraded for steeper gears or a ring gear spacer will need to be used for 3.36 and steeper gear applications.

I have disc brake kits that will work with the pontiac Olds and Buick 10 bolt 8.2 rears also

Depending on where you are I can build yo ua whole diff bolt in ready for cheaper than 2700.00 easy I can probably do it for less than 2000.00 easy.

If your out of the country that could be difficult on the shipping aspect. BUT still might end up cheaper than 2700.00 totally. Jim
J D Race

Valsmere
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Re: 1967 GTO rear gearing help.

Postby Valsmere » Tue Mar 11, 2008 4:03 pm

Hi Jim,
I am located in Cherry Hill New Jersey right next to Philly. My goat is in my brother in laws garage in Vorhees about 20 minutes south of me. It looks like I'll be going with the TKO 600, its their close ratio trans, built a little bit better for street apps. Right now it looks like I'll be more interested in the 3.73 combo and I will need the rear dics brake option. Now I'll just have to find someone to do the install for me, I have no experience with rears at all. Although I have been getting a real education lately with all this research! :lol: Since I'm on my way to work right now, I can send you the specs on the transmission in the morning if you want to get a clearer picture of what I'm up against. Afterall I want to make this car streetable. I will be in touch again tomorrow. Thanks for your help. It really looks like a better way to go than before.

Valsmere

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monzaz
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Re: 1967 GTO rear gearing help.

Postby monzaz » Thu Mar 13, 2008 9:59 am

Val, It might be easier for me to just build the whole rear for you out right and you just keep the rear you have intacted for a spare. As for shippng it really is not that much 100-125 if your going to a commercial (dock, your place of work or truck freight terminal in yoru area) We are actually vacationing in eastern PA west NJ area in the spring so that might be an option too.
Now 3.73 was never a factory ratio for the pontiac Buick or olds rears 10 bolt 8.2 bolt in axle rears. I can install 10 bolt 8.2 chevy gears into this housing with very light mods or trouble for you if you really want that ratio. Which we have done before.
Your aftermarket ratio options for your diff are as follows - 3.55 3.90 4.10 Now you can see why we retro fit 10 bolt chevy gears into these housings...lol. chevy aftermarket gears are as follows - 3.08 3.36 3.55 3.73 4.10 4.56 Jim

Like I said I have many Housing here we can build with very minimal core charge...plus the housing will be media blasted clean and primed painted up chassis black real nice. Also you will not have to find anyone in the area to build it and it will be pretty much a bolt it in, bleed the brakes, break in the gears and then go have fun.

Just let me know another option for you to knaw on...:)
J D Race

Valsmere
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Re: 1967 GTO rear gearing help.

Postby Valsmere » Fri Mar 14, 2008 8:11 am

Hey Jim,
Yeah the whole new rear is the way that I have been leaning towards. I need to talk to my sales rep from tremec to see which one they would recommend. I like the idea of keeping my old setup intact for a spare. I have been trying to figure out how hard it would for me to swap out that assembly myself after I get it. I will keep you posted as per what I'll be doing. One problem I'm running into is the fact that work has been really picking up and to find time when you put in 10 to 12 hours on the night shift is a little rough.
I think there is a trucking depot near me I'll find out who it is. As far as the rear ratio, Ill get back to you on that. I have the trans gear ratio on hand some where, I'm going to see if the sales rep has a thought. Thanks Jim, I will get back to you soon!
Valsmere

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monzaz
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Re: 1967 GTO rear gearing help.

Postby monzaz » Wed Mar 19, 2008 9:02 am

Tranny, Well give the tranny shop your engine specs and they might be able to give you a clearer picture of a ratio that best suite the shift points in the tranny. You also need to tell them what kind of drive your doing MOSTly and what you expect the car to do. More info you can give the better out come you will get and keep talking to other people that have done this or have the tranny in a car already. see if you can go for a ride.

I am always here when ever so do not hesistate and keep use appraised of the situation. Take care, Jim
J D Race


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