HOZZMANRX7

iTrader: (43)

Answer, only the GTUs per Mazda factory cross reference replacement manual as presented by my friends at Mazdatrix.

Anyone that thinks differently about their non TII or GTUs stock rear differentials, jack up your rear end. If you turn one wheel and the other turns the same way, send a e-mail to Mazda and let them know. :-)

There, aren't you glad I cleared up that mystery too? :-)

MaxRX7

do GXLs "suppose" to have LSD or do they ?

HOZZMANRX7

iTrader: (43)

GTUs were set up as much like a TII as they could, without doing the Turbo, including LSD. They just went to a 4.3 gearing for the extra off the line jump.

However for what its worth, the guy at Mazdatrix had a real low opinion of the GTUs LSD design.

Icemark

Your information is only partially correct, It is correct for the series 5 cars, but incorrect for the series 4 cars

Perhaps your friends are confusing the clutch type LSD with a fluid type LSD only found on the 89-91 GTUs and Turbos.

For example the 88 GTU was not available without a clutch type LSD installed at the factory.

Rotary Racer

<-- has stock LSD hehe

Sniper727

What's not to like about the GTUs LSD? it keeps me sideways!

Node

iTrader: (1)

lol sniper
what does a GTUs have that a GTU doesnt? I thought they were almost the same, just GTUs was Limited and had some very small diffs

Icemark

The 89-90 GTU was the strippy car. Single piston brakes, smaller brakes, solid rear brake rotor.

The GTUs, has/had: LSD, Dual piston front brakes, larger vented rear brakes, The suspension of the turbo, alum hood, 4.3 rear end (instead of the 4.1 found on all the other 5 speeds), 17.2 steering ratio (instead of the 15.2 found on all the other cars).

supergoat

My 88GXL has one.

Xentrix

what about the 89-91 gxl's?

Ben L

Icemark,
GTUs has/had 17.2 steering ratio? not the 15.2?! humm.. does that mean GTUs doesn't have power steering?
please explain, thanks

Ben L

Icemark

Nope the only series 5 cars that had LSD from the factory were the T2 and the GTUs.

Ben L:

Nope the manual racks were 20.3 ratio. The 17.2 ratio power steering was a engine speed sensitive rack that was re-valved for the GTUs. (why they didn't go with the vehicle speed sensitive rack from the 88 GTU I don't know... cost I guess).

Ben L

"Nope the manual racks were 20.3 ratio. The 17.2 ratio power steering was a engine speed sensitive rack that was re-valved for the GTUs. (why they didn't go with the vehicle speed sensitive rack from the 88 GTU I don't know... cost I guess)."

speed sensing or vehicle speed? which one you prefer?
thanks
Ben

Icemark

Engine speed sensing tends to be less linear as vehicle speed sensing. Many people won't ever notice, unless they were racing on track. I notice and prefer vehicle speed sensing, or even better, no power steering at all.

Its kind of like those rear steer bushings on the FC. The majority of the time you would never ever notice, but at 9/10ths you do/can.

On the other hand engine speed sensing is great for parking in the shopping mall and when driving under 20 MPH.

HOZZMANRX7

iTrader: (43)

Ok, Icemark. Your probably right. Thinking about it, i guess it was a Series 5 book we were looking at.

Two question to you......

1. which in your opinion is better, the clutch type or fluid type LSD, and why?

2. On the series ('86-88) rx7's, which had Clutch LSD and which didn't.

Icemark

Actually I think the Torsen type (like the FD has) is a better choice than either, but of the two, the clutch type engages much faster, however it usually needs parts replaced by the time it gets 120k miles on it as it wears out with daily driving.

The fluid type only advantages is that it doesn't wear out as easy and you can use standard tranny/diff oil rather than something with a LSD viscosity limiters (like clutch type require).

The 86-88 GXL (it was an option one of those years, but most came with it anyway), 87-88 Turbo, and 88 GTU had the clutch type LSD on the series 4 cars.

the_glass_man

iTrader: (2)

My 86 Sport has LSD.
Don't the most of the early Sport models have them?
Its like the Turbo with out the Turbo.
Vented Disc
Springs, Shocks, etc...

rxspeed87

my 87 sport is SOL as far as the LSD goes

oh well


hell even have the steel hood

Icemark

sports didn't have the LSD or alum hood. Here is an ad for the US for the sport, lux model and GSL

Icemark

The Sports didn't come standard with a LSD, it may have been added on by the previous owner.

Here is a window sticker from a sport:

Rotary Racer

No sunroof hehe

The Ace

Mine has everything (from LSD to AC, and from PW to CC)

80'StyleFC

does the 3rd gens torsen type Diff bolt up to the 2nd gen drift shaft......would such a mod be worth it?

Icemark

I haven't tried so I cant say, however one of the RX7 aftermarket parts stores (like Mazdatrix, or RB, or someone) has a torsen type for the FC. I remember seeing it surfing, but I didn't remember who had it.

If you were needing to replace a LSD or were driving a lot in bad weather, or racing; the Torsen type would be worth it. Instead of locking the axle (like most LSD do) it transfers the power to the wheel that has the most traction.

A conventional diff allows the power to transfer to the wheel with the least amount of traction (example: you are turning around a corner and the inside wheel lifts a little, you would hear that inside wheel spin/squeal just a touch with a conventional diff and not have as much traction).

supergoat

Yet another question for Icemark.

Hey, how can I tell if my LSD needs to be replaced? What tests can I do to ensure proper operation?