gear ratios - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 08-19-2006, 06:19 AM   #11
Senior Member
Posts like a Turbo
Thread Starter
 
Join Date: Jul 2005
Location: Lancaster, South Carolina
Posts: 233
Thanks: 0
Thanked 0 Times in 0 Posts
spidey3479 is on a distinguished road
Default

If the gear ratios are different can I have mine changed to suit the cutlass tranny. Or should I just ingnore the high revs as just the way the tranny will work in my bonne.
spidey3479 is offline   Reply With Quote
Old 08-19-2006, 07:15 PM   #12
Senior Member
Certified Car Nut
 
Join Date: Oct 2003
Posts: 19,756
Thanks: 0
Thanked 0 Times in 0 Posts
1993 SLE is on a distinguished road
Default Re: gear ratios

Quote:
Originally Posted by clm2112
Question on the same line. Can the gear ratios be changed during rebuild?
)
yes

http://60degreev6.com/showthread.php?t=25032
1993 SLE is offline   Reply With Quote
Old 08-19-2006, 11:34 PM   #13
BANNED
 
Join Date: Aug 2002
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
banned3800 is on a distinguished road
Default Re: gear ratios

Quote:
Originally Posted by clm2112
Question on the same line. Can the gear ratios be changed during rebuild?

Let say you start out with a 2.97 final drive ratio transmission, can the components that make the final drive ratio 3.33 be installed in it? Or is there something different in the transmission case that prevents it?

(Just thinking out loud.. might be interested in taking my 90 LE and giving it a quicker transmission ratio)
Be careful there as the 3.33 ran the 3800 series I out of breath too fast... I would go with the 2.97 or the 3.06

But yes during a rebuild it is possible to change the gear ratio

__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
banned3800 is offline   Reply With Quote
Old 08-20-2006, 01:23 AM   #14
Senior Member
Posts like a Turbo
Thread Starter
 
Join Date: Jul 2005
Location: Lancaster, South Carolina
Posts: 233
Thanks: 0
Thanked 0 Times in 0 Posts
spidey3479 is on a distinguished road
Default

Ok, so taking the info from JR3800 that my 88 sse has a 2.97 ratio and the cutlass' tranny was set to run 3.33. That means that my engine has less teeth on its side of the chain than the tranny. So it is going to have to run with more revolutions(work harder) to acheive the same shift pts than when the tranny was in the cutlass. This is like when you go to a lower gear on a 10 speed bike to get more of a workout without making the bike go faster, right? Now, my next question is, will this bring my engine to a quicker demise, or can I take any computer parts or my whole ecu from my cutlass and drop it into my bonne and have things change for the better or not? Or do I just take care of it until I can afford to have my original Hydromatic rebuilt? :P
spidey3479 is offline   Reply With Quote
Old 08-20-2006, 09:33 AM   #15
Senior Member
True Car Nut
 
Join Date: Jul 2003
Location: Toronto, Ontario, Canada
Posts: 5,158
Thanks: 0
Thanked 0 Times in 0 Posts
repinS is on a distinguished road
Default Re: gear ratios

Quote:
Originally Posted by jr's3800
Be careful there as the 3.33 ran the 3800 series I out of breath too fast... I would go with the 2.97 or the 3.06
Werd. GX3 tends to keep the car in the higher revs, out of the powerband.
repinS is offline   Reply With Quote
Old 08-20-2006, 01:25 PM   #16
Senior Member
Posts like a Turbo
Thread Starter
 
Join Date: Jul 2005
Location: Lancaster, South Carolina
Posts: 233
Thanks: 0
Thanked 0 Times in 0 Posts
spidey3479 is on a distinguished road
Default

I love it when I am enlightened! Makes me feel like I'm in high school taking my car apart and putting it back together again, only w/o the tools and the mess! Now, do I worry about any damage to my engine from working harder than usual to get the shifts? If so, do I try any of the computer stuff frm my cutlass on the bonne, or is this going to be a custom job? I plan to either get the old hydromatic rebuilt by AAMCO in the next year.
spidey3479 is offline   Reply With Quote
Old 08-20-2006, 02:17 PM   #17
Junior Member
 
Join Date: May 2006
Location: BonnevilleHell
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
clm2112 is on a distinguished road
Default

Quote:
Originally Posted by spidey3479
Now, do I worry about any damage to my engine from working harder than usual to get the shifts?
Hmm, "working harder" is not really the right way of looking at this. In fact, the engine is working easier with the higher gear ratio. The transmission is providing more mechanical advantage to accelerate the car, so the engine doesn't have to work as hard at moving the car.

Make sense? The higher gear ratio came out of cars with an engine that had a higher rev limit and produced less power across the board (the 2.5L 4cyl, 2.8L V6, and 3.1L V6.) Kinda like my '87 2.8L V6 Camaro that came from the factory with 3.23 gears as opposed to the 2.xx gears that were stock in the V8 cars. The numericlly higher final gear ratio tried to make up for the dismal power output. If I remember correctly, the 2.8L V6 capped out at 6,000rpm redline (6,500rpm cutoff) vs the 5,500 rpm limit on the SBC V8.

Now, the $1,000,000 question: What is the practical RPM limit on the 3800 (LN3 style) ?

If things work the way I'm used to seeing it happen, valve springs are normally the first limit to the engines RPM limit. The stock springs can't close the valves fast enough and they end up floating. (Not normally hazzardous to the motor, unless you have piston crowns that intrude into the chamber...the motor just falls flat on it'* face and doesn't want to accelerate any higher.) The correction is to use stiffer springs in the valve train.

Next limit is usally airflow on the intake side..the heads just can't flow enough air to keep up with the motor'* displacement at that rpm. Solution is typically better cylinder heads or porting of the stock heads. Following this is: Airflow on the exhaust side, piston speed, wrist pins, connecting rods, crank, and bearing failures. (the last being in the rediculous rpm range.)

So, from a practical standpoint, a higher gear ratio is usually a good thing if you like to go quick. Unfortunately, I don't have the experience with the 3800 to know when these limits normally get hit. But I'd wager a guess there'* a few around here that do
clm2112 is offline   Reply With Quote
Old 08-20-2006, 07:14 PM   #18
Senior Member
Posts like a Turbo
Thread Starter
 
Join Date: Jul 2005
Location: Lancaster, South Carolina
Posts: 233
Thanks: 0
Thanked 0 Times in 0 Posts
spidey3479 is on a distinguished road
Default

Ok, so I read that backwards and my car having a lower fdr is better for my engine, right?
spidey3479 is offline   Reply With Quote
Old 08-20-2006, 10:08 PM   #19
Senior Member
Certified Car Nut
 
Join Date: Oct 2003
Posts: 19,756
Thanks: 0
Thanked 0 Times in 0 Posts
1993 SLE is on a distinguished road
Default

Quote:
Originally Posted by spidey3479
Ok, so I read that backwards and my car having a lower fdr is better for my engine, right?
dont think if it in terms of better or worse....the lower FDR will give you better gasmilage, but slower acceleration....the higher FDR will give you worse gasmilage but faster accelleration
1993 SLE is offline   Reply With Quote
Old 08-20-2006, 10:12 PM   #20
Senior Member
Posts like a Turbo
Thread Starter
 
Join Date: Jul 2005
Location: Lancaster, South Carolina
Posts: 233
Thanks: 0
Thanked 0 Times in 0 Posts
spidey3479 is on a distinguished road
Default

So this is not hurting anything for it to have the high revs until I rebuild the OEM tranny?
spidey3479 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Gear Ratios Merlin 91/97 1992-1999 1 06-15-2006 08:32 PM
FYI if you lose 4th gear / no fourth gear / no 4th gear caminated2k 2000-2005 6 07-24-2005 11:26 PM
Can someone give me a lesson on gear ratios? ComfyCar General GM Chat 12 07-20-2005 12:39 AM
gear ratios macho_mike21 General GM Chat 4 08-04-2004 04:23 PM
Gear/axle ratios questions OLBlueEyesBonne General GM Chat 9 09-23-2003 04:32 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 06:28 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.