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MG MGB GT V8 Factory Originals Technical - 3.07 gear question and a quaife question

Does anyone one here have anything good or bad to say about the quaife differential? Not for racing, but street usage?

Also, my rover 5 speed has some problem with 1st gear. so basically, i don't use 1st. With the 3.9 rear that's in the car, starting off in 2nd isn't any problem. but if I put 3.07 gears in it, will I still be able to start off in 2nd without a problem? My guess is that I need to hear from someone with a rover engine/trans with a 3.07. Will anyone pull the car out and tell me if it's a bad idea?

I do have another rover 5 speed to put in that should resolve the problem. But My problem is I might not be able to get to it this year. I am also recovering from surgery (which tends to rule out the transmission getting fixed this year).

I do have the 3.07 gears and figure I can put those in within a day or two or three. And of course, the quaife sounds like it mioght be a good deal.

Anyone got advice?

Richard

Richard Morris

The synchro has proberbly died on first.
Can you engage first once the oil in the box has warmed up?


Gearbox rebuild time perhapse...
JC Moulds

Richard,

the setup you are talking about was used on all the RV8 production cars. I never heared anything negative about this rearend.

Maybe you also put your question into the RV8 colume.

Ralph
Ralph

thats a good idea.

The quaife sold, so that issue is not a concern
Richard Morris

Just posted on the other thread. The LT-77 Rover gearbox is the same unit used in all US (UK maybe as well) TR7 5 speeds. Most junk yards don't know this and so you can pick up a lightly used (4 cyl) box for a few hundred dollars or less. Just swap the bellhousing and your'e good to go.
Also I had issues with 1st gear on my LT-77 unit. I replaced a very worn pilot bush (spigot bearing for you poms) with a roller bearing unit. Shifts like silk now. It's amazing what a difference it makes when the input shaft alignment is maintained...
M Mallaby

The Quaiffe is nice but not a true LSD. If you lift a wheel off the ground, you won't get drive to the other one.

On balance, though, I much prefer it to most other LSDs.
Bill Spohn

Richard, You may still be able to start in 2nd with the 3.07 but as it's about 27% taller, it might be a bit stressful on the clutch if your facing uphill! Perhaps an overhaul of the gearbox is due. The 3.9 diff is probably too short with the lower ratio gears in the existing box - enabling you to use 2nd to start but not utilising the gearbox fully.
I have a Quaife with a 3.3 axle and like it (Ford 5-litre). There is absolutely no pushing in corners yet coming out of slower corners it spins both wheels very progressively. Good Luck, Bob Elwin
Bob Elwin

The *best* used LT77 would be the ones fitted to the later O series powered Rover SD1's.
You want a D suffix box with the 0.8 top gear.
Why the o series rover? Because it wont have spent its life having the nuts thrashed off it behind a V8!
JC Moulds

Both my Rover gearboxes are LT77's. The one with the unusable 1st gear (which is currently in the car) was completely gone through by me. What apparently happened is the spring that holds the synchro dogs either broke or slipped or something. If I really try, I can force it into 1st. but then it does not shift smoothly into 2nd. The other gears are all perfect. The other gearbox I have was from a TR7, and has been rebuilt and has a warranty. But I am still going to pull the tail housing and inspect the oil pump. It is just sad that I somehow botched the reassembly of the first one. These boxes are very easy to work on.

It's a real shame to have to pull everything out to get the gearbox off. But, I bet it takes me a lot less time than it did to put it all together.

The quaife that was on Ebay was the one for the 3.07 gears and it would not have required any machining. It sold for $950.00. I was thinking I was going to get for around $700.00 since it was the 2nd time it had been listed. While it would have been nifty to have gotten it, I think I will just stick with the open differential when I put the 3.07 gearset in.
Richard Morris

To follow up on what Bob said, there isn't any pushing in corners as there is with a welded diff (I've run both) BUT you need to remove the rear sway bar if you have one, to balance the car again.
Bill Spohn

Is "sway bar" an americanism for anti-roll bar?

If this is the case and its a later car with the raised ride hight you will need to lower the car otherwise the cars handling will suffer considerably.
JC Moulds

Why would you need (or want) to remove the rear sway bar if a quaife was put it? This doesn't make any sense.

My car has the poly bushings everywhere, 550# springs in tront and the rally springs (with the flipped spring eyes) in the back. It sits a little lower than a chrome bumper car and corners flat with no push or other bad traits. As it sits, my steering is light, quick and very responsive. The new tires and wheels made a huge difference in the way the car felt. (Michelin 195/65 HR15 Pilot Exalto) and extremely lightweight wheels).
Richard Morris

It makes perfect sense. It depends on the ride hight of the car as to choosing to keep the rear ARB or not.

The rear ARB is neccesary at RB ride hight as otherwise it would handle like a jelly.

However, if the rear end is lowered to CB hight and the rear ARB is retained there is a problem with snap oversteer occuring.

The rear ARB has nothing to do with the diff.

Check your ride hight. If it is 14inches from centre of the stainless side trim to centre of the wheel's centrecap then its at chrome hight. The ARB should be removed unless you fancy spending a morning facing backwards in a ditch. RB ride hight is up to 17 inches from trim to c/cap.

-JC
JC Moulds

JC,
The pushing out of a corner "I have a Quaife with a 3.3 axle and like it (Ford 5-litre). There is absolutely no pushing in corners yet coming out of slower corners it spins both wheels very progressively. Good Luck, Bob Elwin" was referring to the tendency of a LSD (or in the worst case, welded spider gears) to try and push the car straight if you apply a lot of power. And that is assuming that you have a lot of traction.

My question was why was it necessary to remove a sway bar if you put in a quaife, which is what was being implied. (Up to that point in this thread, nothing had been mentioned about ride height).

My rear measurement is 14.5", the front is 13.5". As you see from the measurements, it has a very slight nose down pitch. I have a set of lowering blocks that I got for the back to level it out since I still don't care for a "jacked up" appearance. And as is, it is better than any B I have owned for steering, and handling. (I have had a 63, a 74 CB a 76 and 2 80's(one from new)). Prior to my doing all this stuff to this car (bushings, springs etc.) the 74 with delrin suspension bushings had been the best.

Even if I lower the car in the back to level it, I am going to give the sway bar in the back a shot. I can see how lowering it could get the rear bar's geometry out of whack, but loss of a rear sway bar is going to negatively affect handling. (What I am saying is that a rear sway bar that would have the correct geometry would benefit handling).

But to say if you put a LSD type rear in the MGB you need to remove the rear sway bar, is not a correct statement.
Richard Morris

I use a Quaife with a 3.08 with no rear bar - works for me, but with these type of issue drivers preferences can be a big factor.

In general an anti roll bar reduces grip at the end fitted, so a rear arb should be a last resort to solve other issues such as high ride height.

If its being used to correct an LSD issue then a Quaife does not have this "push" problem so the rear arb can be removed if reason why fitted.

A lowered car will give an inclined roll axis which has an effect on the "fast route" weight transfer during the transient phase.
Paul Wiley

Richard,

"But to say if you put a LSD type rear in the MGB you need to remove the rear sway bar, is not a correct statement." - Completely agree. Poor wording on my part?

One would hope that if you are running around in a tuned V8 that you would give consideration to improving the cars traction. 5J 14 inch RO-Styles are all well and good for a 4-pot but a V8 needs a little more rubber on the road.
Anyhow, this is getting away from the point...

MG saw fit not to bother to fit a rear ARB untill the rear ride hight was raised to 17"
If the Rubber bumper ride hight is to retained then so must the rear ARB. It is there for a good reason at that ride hight.
A car at 17 inch ride hight with no ARB would be like a jelly to drive. At best skitish, at worse, downright dangerous!

The ideal setup for these cars when using leaf springs at the rear is stiff front and soft rear.
If the car is lowered to CB hight with the use of lowering blocks then a rear ARB is NOT required.
When lowering a late car to RB ride hight if you retain the rear ARB the car will not be able to tuck down when thrown into a bend hard. The rear ARB will resist and suddenly snap oversteer occurs.
When you get snap oversteer on these cars its a real sod to catch.

If you install a rear ARB on a lowered car you WILL spoil the handling to the point where you can't be quite so commited in a corner. If you do give it the berries, instead of nice gentle progressive oversteer you currently enjoy. The car will understeer followed swiftly by the back end stepping out violently without warning. This, I assure you, is not fun.

-JC





JC Moulds

JC,
I replaced the stock wheels and tires just this last month. I went with 15x5.5 minilight (polished) with a set of Michelin 195/65 HR15 Pilot Exalto (see prior message). Traction issues have been resolved. And the larger diameter wheels and tires made an enormous difference in the ride. (much better).

After thrashing this topic around, I have made the decision that when I lower the rear a little more (recall it sets at 14.5) I WILL remove the arb. Your points are all made and once I see logic behind something, I accept it.

I suspect that I just haven't pushed it hard enough in a corner at this point to have had a problem or I am still in the height range that the bar is still working in my favor.

Richard
Richard Morris

Good move Richard,
When I lowered my V8 rubber bumper I initially left the bump stops as is. These then prevented adequate suspension movement, like an antisway bar. Horrible snap overstear, nearly killed me on one occasions. After I cut an inch off the bump stops the snap went away.
I initally lowered the car by a combination of one inch blocks and redrilling the spring hanger. Over a period of time the spings sagged a little (about1/2 an inch), so I put the hangers back as before. the car sits about 14.5" now. Rather oddly, I have found that this has imporoved raodholding. More roll in the back,more rubber on the road. This lends credience to those who take a leaf out of their rear springs to soften them.
Peter

Richard, have a look on www.upgrades4mgs.co.uk
There are some good articles on there. The ones I have written, less so! ;)

Phil Earls suspension pages are worth a read. Having been a passenger in the GTK and Having driven the 1980 GT owned by the webmaster I can assure you that compared to standard both of these guys have made leaps and bounds over the standard setup.
That is not to say standard setup is bad which all barroom experts would have you believe. Comparing an old car on tired standard suspension to one on new uprated stuff is unfair. Direct comparasins should only be made between the new uprated stuff and a car on brand new standard components.

I think we are proberbly on the same page more or less when it comes to handling.

Just as a matter of interest I am running on 15inch 6.5J Wolfrace slotmags. They DO fit on a standard car believe it or not. Im convinced my axle is better centred than most. I am borrowing a friends car whilst mine is getting its V8 transplant. The 5.5J scimitar (factory V8 lookalike) wheels I took off rub quite badly on the drivers side.
The idiocynrecies of old cars, eh?

Take it easy,

JC.
JC Moulds

Ha! Richard your post has been totally hijcked.

JC what is the offset on those 6.5" rims?
M Mallaby

This thread was discussed between 15/03/2007 and 22/03/2007

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