Quick question transmission/gears

[Omnivium]

I have a olds 307 in my 87 Regal T and was somewhat interested in changing my gears to 3.73 or something now is it recommended or required to rebuild your transmission? Or that doesn't matter? I have the 200-4r OD transmission. If I;m looking to do this should I have my transmission rebuilt, can someone explain this for me hahah thanks

 

[Evan11]

Re: Quick question

Changing rear end gears doesn't have anything to do with the trans. If the trans shifts well & isn't causing any problems, there's no need for a rebuild.

 

[Omnivium]

Re: Quick question

Changing rear end gears doesn't have anything to do with the trans. If the trans shifts well & isn't causing any problems, there's no need for a rebuild.

So correct me if I'm wrong I can just change the gears without a whole new rear end or that wouldn't work, sorry for the noob questions lol

 

[vonclod]

yes you can buy a ring and pinion set..just need to figure out what rear you have..should be an 8.5 if its a t type

 

[lilbowtie]

The only thing you might want to change in the trans is the speed "o" gear so your speed 'o" reads correctly

 

[horners85regal]

and good luck finding the gears for the speedo ! i just finally found my 27 tooth driven. took alot of searching.

 

[Omnivium]

how do I know what rear end I have? because I have no idea, 87 T with a olds 307. I know it has a posi rear if that means anything and 200-4r OD transmission.

 

[vonclod]

a 7.5 has little fangs on the bottom and the 8.5 doesnt..i,ll put a link up that has a few pictures
http://www.oldspower.com/vb/showthread.php?t=31398
as for what gears the only way to know for sure is open the diff cover but if they came with the car you will find a sticker in the trunk lid with all the codes..you should have a G87 in the mix..that indicates an 8.5 and a G80 indicates that its a posi..which you already know..other codes in the link below will tell you the ratio
viewtopic.php?t=5155
just sharing what i,ve been learning as of late
cheers

 

[Evan11]

Being a t-type, it should have a 8.5 with 3.42 or 3.73 gears.

 

[Omnivium]

a 7.5 has little fangs on the bottom and the 8.5 doesnt..i,ll put a link up that has a few pictures
http://www.oldspower.com/vb/showthread.php?t=31398
as for what gears the only way to know for sure is open the diff cover but if they came with the car you will find a sticker in the trunk lid with all the codes..you should have a G87 in the mix..that indicates an 8.5 and a G80 indicates that its a posi..which you already know..other codes in the link below will tell you the ratio
viewtopic.php?t=5155
just sharing what i,ve been learning as of late
cheers

Thank you so much! 7.5 rear end with 3.08 gear ratio. So would going to lets say 3.73 be a big increase
? Headers and duals are on the way! Hoping to have the full exhaust system done by the end of May