gear ratios - Page 3 - 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 08-20-2006, 10:29 PM   #21
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

Quote:
Originally Posted by 1993 SLE
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
Generally speaking. Haven't tried side by side myself, but I'm a believer that with the LN3, the 2.97 FDR would be a bit quicker than the 3.33.
repinS is offline   Reply With Quote
Old 08-20-2006, 11:30 PM   #22
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
So this is not hurting anything for it to have the high revs until I rebuild the OEM tranny?
Not really, so long as you are not exceeding the rev limit on the 3800. The motor should be able to run at the rev limit for an indefinate amount of time without doing any harm to the motor (That'* the whole purpose of a rev limit.)

Now, joining back to your problem from a few days ago: Because the Cutlass transmission was set up for a motor with a higher rev limit, it probably is still trying to use the 3.1L Cutlass setup to do it'* shifts. This is where it get'* sticky, since you have jumped off the normal diagnostic charts into a whole new realm. (Ain't part swappin fun!!!)

I would venture a guess at this point that the governor in the transmission is what is causing the higher than normal rpm up-shifts. The governor uses the vehicle speed (it'* gear driven off the output shaft) vs. line pressure modulated by the Thottle Valve and vac operated modulator. Problem is, it doesn't "know" the rev limits on the motor driving the input shaft. It was calibrated for the 3.1L motor and the Cutlass weight. What you might need is a governor calibrated for the Bonneville'* weight and the 3800 motor.

Good news is the governor is easy to get to. It'* on the top of the transmission right where the passenger side axle exits the case. You don't have to dissassemble the transmission to make a change to it'* springs and weights.

Bill: Thanks for posting the link to the drive ratios. Made lights go off...I'm not used to having *all* the gears inside the transmission case. Just takes some getting used to. At least I dug up the build sheet for the '90 and looked at the codes for mine: F17 - 2.84 final with a 1:1 chain...so I keep my eyes peeled for an FW2 code in the junkyards (for the 3.06 final)
clm2112 is offline   Reply With Quote
Old 08-21-2006, 12:57 AM   #23
BANNED
 
Join Date: Aug 2002
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
banned3800 is on a distinguished road
Default

Curt I love your explanation... Can't wait to meet you in person at the meet...

The 3.33 ratio will not hurt the 3800... They can be a fun around town car with that gear ratio.... The old LN3 3800 are some pretty good war horse engines... I feel that 2.84 is a bit too heavy( even tho the engine does make great low end torque for what it is )... The 2.97 would have been the optimum ratio in my opinion... But even my junker 91 SSE with the 3.33 ratio is on the original trans and engine at 250k ... So no I do not feel it will harm the engine...

If we look at the 2.84 ratio, at times it seems as if the tall ratio tends to lug the engine a little at low speeds... But I have yet to hear of any engine that has failed... I have found a couple of 88 LN3 engines that even had the 2.73 gear ratio...

I feel that these engines really don't need to spin much past the redline, But getting them to 5500 has never seemed to be a challange... But it HP peak is 4400 rpms so there is almost no point in being there....

__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
banned3800 is offline   Reply With Quote
Old 08-21-2006, 01:33 AM   #24
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

Thank you, thank you! Do you think I can just take the governor from the oem tranny and put them in the olds' tranny I have in the bonne now? Or should I try getting a new one from somewhere. (tranny parts warehouse or junkyard)
spidey3479 is offline   Reply With Quote
Old 08-21-2006, 01:50 AM   #25
BANNED
 
Join Date: Aug 2002
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
banned3800 is on a distinguished road
Default

Quote:
Originally Posted by spidey3479
Thank you, thank you! Do you think I can just take the governor from the oem tranny and put them in the olds' tranny I have in the bonne now? Or should I try getting a new one from somewhere. (tranny parts warehouse or junkyard)
I'd say best bet is to look for an 89-91 Bonneville SE or SSE with the F79 RPO for the 2.97 Ratio... I have in the past found a few that actually had a SRTA Factory reman trans( Hydramatic Factory Rebuild )....

So Far I have been lucky with my 2.84 Trans in my 91 LE... Its still going

__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
banned3800 is offline   Reply With Quote
Old 08-21-2006, 02:08 AM   #26
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

Thanks to all for all the info I will try to get all this down to carry with me to junk yards around here. When I call some of these guys will they understand all of what I am describing with the drive ratio or RPO or do I ask for the right years and just go hunting myself?
spidey3479 is offline   Reply With Quote
Old 08-21-2006, 02:15 AM   #27
BANNED
 
Join Date: Aug 2002
Posts: 0
Thanks: 0
Thanked 0 Times in 0 Posts
banned3800 is on a distinguished road
Default

Some will know what you are looking for others could care less or may not know...

You will want to take a look at the RPO listing on the spare tire cover... Also I would reccomend 90-91 for the trans as opposed to the 89... Unless the 89 has an SRTA, or is a low milage unit... The 90-91 has some updates to correct for issues they had with the earlier units... Make sure you have the 5 wire tranny electrical connector like your car to save you a small headache... Other than that just make sure the tranny fluid isn't black or burnt...

__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
banned3800 is offline   Reply With Quote
Old 08-21-2006, 02:35 AM   #28
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

thanks again, a hunting i will go, a hunting i will go
spidey3479 is offline   Reply With Quote
Old 08-21-2006, 07:08 PM   #29
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 jr's3800
Curt I love your explanation... Can't wait to meet you in person at the meet...
Might be a bit of a let down. In person I'm pretty much a cross of Pittsburgh Iron-City swilling mill-hunky and West Virginia hick. (Even made moonshine once in my misguided youth on the farm.)

Spidey: You sound like you are on a roll now. If you've picked a tranny shop to rebuild your existing one, talk to them about the governor on your existing transmission. They may be able to reach into the magic parts bin and pull out a good choice of weights and springs to fix the problem without you having to go junkyarding.

There'* no harm in plopping the governor from the original Bonneville into the Cutlass transmission. It may work right, it might not, but the attempt costs you nothing but a little time to try it.
clm2112 is offline   Reply With Quote
Old 08-21-2006, 07:30 PM   #30
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

tanks dude!
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 05:48 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.