so i see alot of threads about people talking about 3.73 gears or gears in that range. i have a 84 buick elctra and i was looking at getting a new set of gears for it and i found these http://www.summitracing.com/parts/CMB-14-0054/ http://www.summitracing.com/parts/RMG-6901751/ would these fit and what would be better for racing and slight use on the street. gas milage is not a huge issue. im just wondering if those would be too much gear for a eventual 455 swap. also i want to put in a posi, what brands/types should i look at more and should i do it all at once or can i get the gears now then when i get some more money together get the posi and install that later?
3.73 is all you would ever need for your car. 4.56 and 5.57 are for 1/8 mile racing. That 307 in your car literally drops dead after 3500 RPM. Forget about gears for now. You need a motor transplant first.
I totally agree with Larry. I have 4:11's with my 455 and a 28" tall tire. I wish I had 3:73 or even 3:5's. You only need crazy gears lke that when you are either 1/8th mile racing or you have a motor that doesn't make power until you get some RPM un it. The torque of the 455 starts waaay low so you don't need those gears.
ok. thanks. so even tho most of its life would be at the track (1/4mile) those are way to much if i plan on putting in a 455 and building it?
You need to plan out a combination before you start buying parts, all the way down to planned tire height. Decide on an ET/MPH you want to shoot for, which will tell you how much engine you'll need. Then you'll know approx at what RPM you'll be shifting and what RPM the engine will see at the end of the 1/4 mile. Then, based on transmission (overdrive or not) you can choose tire height and final gear ratio to get the rpms you want. Not something you will want to take pot-shots at, see? Devon
Way too much is right. A BBB is a low RPM torquer. No need to spin them past 5500-6000 RPM. With 3.73's, and a trap speed of 110-112 MPH, I'm at 55-5600 RPM. With 4.56 gears, 112 MPH would be about 6800 RPM. With 5.57 gears 112 MPH would be 8200 RPM. See why those gears are not desirable for you? Ideally, you want to be going through the traps at the RPM your motor makes peak HP. For a mild 455, that will be between 5000 and 5500 RPM.
wow... thanks guys for the info! my only goal so far is to get it way faster than it is now. gonna have to do quite a bit of research. thanks for the help. any tips on a posi to get?
are there any other model cars that i can get 3.73 gears from and possibly a posi that would fit in my car? i think it is a 8.5" 10bolt...
Contact Monzaz on this board. Send him pictures of your rear. I'm not sure what they put in your car, but it is probably the 8.5. Make sure before you order parts. Jim can set you up with whatever you need. PM Monzaz. http://www.v8buick.com/member.php?u=3880 www.jdrace.com
7.5 rear. pretty small for the size car you have... But we have plenty of parts. Thank goodnees you showed the pictures as you would have bought the wrong size gears for your car. You were going to by 8.5 10 bolt ...As stated you have the smaller 7.5 rear. If you have a pick a part car junk yard by you look for a impala ss or old cop car ot even a 1990 -1996 buick roadmaster as these rears are bigger 10 bolt 8.5 and will bolt into your 1984 rear and have better gears like 3.08 3.23 3.42 ish and alot of time a posi and the rears will be 30 spline axles AND may even come with disc brakes AND may only cost you 100.00. I can supply you with a posi and gears if you like for that rear which will be easy too. 3.42 would be a great up grade. Do you have overdrive then I would say you could do 3.73. PM me if you need more help. Finally do not bother with that Richmond install video tape...it will not help if you do not know what your doing in the first place. Your better off with a GM manual and some one that can explain the short cuts and in and out of the diffs for you. Just pm me I will help you I have helped many set-up rears and I have never even seen them. All internet and phone. Take care and good luck in the choices you have. Jim
Not trying to take over this thread, but i also been considering a posi. 3.73 gear unit for my 68 skylark, with a recently install 455, and TH400 transmission. Something for around town and sometime highway cruiseing. picture of what is currently installed, maybe ya'll can figure it out, what i have and what can be installed in it ?
thanks alot monzaz! saved me a lot of problems... i thought i read somewhere on the net that i had a 8.5. good thing i didnt get anything yet. gonna go to our local picknpull tomorrow to see what they have there. ill deffinetly check out those cars u mentioned. that would be nice to have everything i needed in one package deal.
3.73 is not a good ratio for highway use. It is not needed for a 455 which has great low end torque. Get a 3,08,
You need to get your engine and trans issues diagnosed and fixed before focusing on your rear end ratio. It is not the cause of the issue you laid out.
i dont want to dump a ton of money into the engine when im just gonna turn around and replace it... the rear end will be there with either engine. thats kinda why i was focusing there. what else should i look into for the engine and tranny like you are saying? im already thinking bout getting a carb rebuild kit for the qjet. dont know what els too look at tho
I do not know why your engine only revs to 3500 rpms and I assume that you do not either. It could be a fuel supply issue to the engine; it could be a trans issue etc. You need to get this diagnosed and repaired first. Then it may become obvious that a change in the rear end ratio is not required.
well id figure id want it replaced anyways cause my goals are to take it to the strip but i will keep looking into the engine. and im not 100 percent sure on where it stops revving at due to no tach. should i look into the distributer?? worn out tabs? im not too sure what could be wrong. this is my first carb'ed car. my commuter is a 04 ford focus svt, so this is a whole new world
o yea. the reason my parents stop driving the car is because a lifter went out 6-7 years ago. i helped a mechanic friend of the family replace it, it was cylinder number 7. dunno if that helps at all
