Opel GT Forum banner

21 - 37 of 37 Posts

·
Member
Joined
·
1,182 Posts
I guess, choice of differential ratio is personal preference and how you use your car. Also, larger displacement engine (I run 2.5) provides plenty of power and torque for brisk acceleration even with standard differential. I mostly drive long road trips, so when I added Quaife LSD, I made special effort to keep standard 3.44 diff ratio. Two days ago I drove my GT eleven hours from Pennsylvania. I certainly enjoyed keeping 75 mph at some 2600 rpm. But for smaller engine short ratio could certainly be fun when jumping from traffic light to traffic light or for the track event.
How are you getting 75mph at 2600 RPM?
 

·
Registered
Joined
·
1,608 Posts

Attachments

·
Registered
Joined
·
1,608 Posts

·
Registered
Joined
·
518 Posts
Taller tires then, with the stock 165 13 size the speed would be 66,16MPH, or 106,45km/h in metric.
(0,5992m x 2600RPM) : (0,804 x 3,44) x 0,189 = 106,45km/h : 1,609 = 66,16MPH.
 

·
Registered
Joined
·
14 Posts
Don't know if I can solve your problem but I'm down to my last two rears. I'm in North Jersey about 30 miles West of NYC and have had a number of MD. Opelers come up to get larger parts such as heads, 4 speeds, seats, etc. Contact me if you are interested and I've sold others for about $150.
 

·
Registered
Joined
·
44 Posts
I thought if you jacked up 1 rear wheel and turned it 1 revolution the driveshsft would turn 3.67 times (making it easier to compare, 6 revolutions of the tire would be 22 at the drive shaft. The 3.44 rear would make slightly less than 21 turns so it should be easy to determine. Of course, if you have a limited slip differential (or locked!), it won't work IIRC.

The difference between .81 and .804 in 5th would be about .04 at the rear axle so, not a 3.44.

Doug
If you lock one wheel, the other wheel will spin twice as fast compared to when both wheels are spinning. Therefore, when jacking up one wheel and spinning it one turn the driveshaft will turn 3.67/2 =1.83 turns.
 

·
Registered
Joined
·
41 Posts
Discussion Starter #28
Gentlemen, thank you all for your contribution, whether I should go 3.89 or not

@mgwinner, sorry to have "hacked" your post, and I excuse for the slight detour it have taken from you original question. Don't mean any harm.

Cheers
no problem, I did finally find the isuzu information but new ring and pinion gears for a mid 1980's Isuzu is as extinct as the Opel.
 

·
Registered
Joined
·
2,547 Posts
If you lock one wheel, the other wheel will spin twice as fast compared to when both wheels are spinning. Therefore, when jacking up one wheel and spinning it one turn the driveshaft will turn 3.67/2 =1.83 turns.
Thanks, I knew something was missing! :pat:

Still, enough to tell the difference between a 3.44 and 3.67 after 6 turns of the wheel.

Doug
 

·
Registered
Joined
·
901 Posts

·
Registered
Joined
·
41 Posts
Discussion Starter #31
Don't know if I can solve your problem but I'm down to my last two rears. I'm in North Jersey about 30 miles West of NYC and have had a number of MD. Opelers come up to get larger parts such as heads, 4 speeds, seats, etc. Contact me if you are interested and I've sold others for about $150.
sorry i just now saw your post, I am going to setup the other rear from the parts car and see if it whines as well, I'll keep you in mind if this one is as loud as the last.
 

·
Registered
Joined
·
1,562 Posts
I was reading on the Quaife limited slip rear end, has nay one use one. Not a heck of a lot of difference in price from the Opel rear end and the quaife rear end. If it really is better I think I would go with the quaife. Comments are welcome.

Bob
 

·
Registered
Joined
·
518 Posts
Depends on the usage, on the streets and the highway or at track days a Quaife will be a good choice. For serious racing or track day driving a ZF 004 or 006 clutch LSD will be better because they can be built to specification regarding ramp angles, amount of clutches etcetera to get the wanted characteristics like transmitted torque and preload. Stock street and road driven Opel ZF's usually transfer 40 - 45% of the torque to the wheel with the least resistance while racing models transfer 75%. 100% transfer would mean the same as a spool. A Quaife diff will also stop the transfer if one wheel is off the ground or if the difference in friction between the driven wheels is big. A clutch LSD on the other hand will wear of use, and the more preload and torque transfer to the other wheel there is, the faster it wears.
 

·
Opel Rallier since 1977
Joined
·
1,103 Posts
Here is some useful info on the Quaife.... As this tells you, in some situations, it will behave like an open diff. So, not really the same animal as a traditional friction plate type of LSD. (It would be fairly useless in rally conditions for example or on any rough road/surface situation.)

https://mgaguru.com/mgtech/rearaxle/ra302c.htm
 

·
Opeler
Joined
·
3,567 Posts
I installed Quaife LSD in my GT some five years ago. Running 180HP 2.5 engine, my main motivation was to eliminate notoriously weak Opel spider gears. I am very satisfied with Quaife LSD as unlike clutch type LSD, it does not affect driveability at all (no understeer) and requires no maintenance. It requires synthetic oil, though. For the street and road driving, it is ideal LSD.

For sport applications, look for a disc (clutch) type differential, like ZF.
 

Attachments

·
Registered
Joined
·
1,608 Posts
I installed Quaife LSD in my GT some five years ago. Running 180HP 2.5 engine, my main motivation was to eliminate notoriously weak Opel spider gears. I am very satisfied with Quaife LSD as unlike clutch type LSD, it does not affect driveability at all (no understeer) and requires no maintenance. It requires synthetic oil, though. For the street and road driving, it is ideal LSD.

For sport applications, look for a disc (clutch) type differential, like ZF.
Very nice Pj!
 

·
Super Moderator
Joined
·
5,609 Posts
I installed Quaife LSD in my GT some five years ago. Running 180HP 2.5 engine, my main motivation was to eliminate notoriously weak Opel spider gears. I am very satisfied with Quaife LSD as unlike clutch type LSD, it does not affect driveability at all (no understeer) and requires no maintenance. It requires synthetic oil, though. For the street and road driving, it is ideal LSD.

For sport applications, look for a disc (clutch) type differential, like ZF.
I have a Torsen (which I believe the Quaife differential is) differential in my Lexus IS300. It works very well, and provides far superior traction to an open differential, even in snowy conditions, although the traction control no doubt assists in reducing single wheel spin.
 
21 - 37 of 37 Posts
Top