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MG MGB GT V8 Factory Originals Technical - Best rear end option? LSD necessary?
|I've read a lot about this in the archives, but I seem to be less sure of my decision than when I started. I've got a '96 disco V8 & GM T-5 (.63 od) already. Which of these options would be best? (Inexpensive is better, but not at the cost of sturdiness)|
1.Replacing the CW&P with the one Mike Satur has for sale. Supposedly fits right in the stock MGB rear, with no modifications necessary. Anybody got experience with this type? Is the stock B strong enough? Pros and cons?
2.Buy a ready to bolt in Ford 8" from Glenn Towery (more familiar with MGBs) or Currie Enterprises (closer to me). I assume the both do it the same way and both are listed in Roger Williams' "...V8 Power" book. And I could get an LSD, too.
Which leads to another question. Do I really need a limited slip diff? I don't race or autocross (what class would a v8 B fall into anyway?-I'll post a separate thread for that question), I have a split street/freeway drive to work, and really enjoy the curvy 2 hour drive to the mountains of Northern AZ where my parents have a cabin, or going to LA or Vegas or Mexico. I'm much more of a high speed cruiser than a dragster type driver.
|LSDs are sweet. You won't lose forward traction if one wheel hits a wet spot! The Quaife unit that slips into a B/C pumpkin (which is essentially a Torsen gear-based design functionally similar to what they used in RX-7s) is perhaps sweetest of all, because it does not induce understeer as clutch-type LSDs (i.e. nearly all of the Ford/GM units) can. The B/C axle assembly, due to the # & arrangement of the bearings, is stronger than a Ford 8" (but clearly not even close to the strength of the redoubtable Ford 9"). Putting the 3.07 cw&p into your axle is a job that must be done by pros, or it will whine to high heaven. Your mechanic better be aware that the pinion crush sleeve is NLA and he needs to do his flat best not to ruin the one you have. To my mind, the best rear end to put under a V8 is a B/C 3.07 or 3.31 with the Quaife. I wish I could afford one ... Waterloo drivetrain systems wants $1800 for one of these!|
|I will only address the LSD question. My personal experience with LSD on the street is that I felt that it made driving more dangerous in the conditions you would expect it to be most usefull; wet and icy. Without LSD, one wheel will spin and the car generally continues in a straight line, but with LSD, both wheels spin and you find yourself drifting off the road quickly if there is much crown in the road. I never hit anything nor ever damaged the car, but I had to be much more careful on thottle application with LSD than without in wet conditions.|
|George is certainly correct. In a car with gobs of torque and not a whole lot of weight on the rear wheels, this can be a real issue. Again, the gear-type units e.g. Quaife will display this effect a bit less, but it's something to keep in mind.|
|Jim, do your homework! With a .63 O/D you DO NOT need to change the rear gear ratio! With a 3.9 & the .63 O/D you will have the same as I do with the rover .8? O/D & the 3.07 gears.|
Can I take that to mean the stock rear will handle the Maximum Torque: 233lb-ft @ 3000 rpm (1996 Rover specs)?
|Glenn is correct. I have a Ford T5 with .79 And yes the MG rear is as strong as the 8 Ford My 3.9 has gone through racing duty and now street duty, after 23 years still running with a little bit of gear noice at high speed.|
First gear may be a bit low, just do a fast change to second.
|An interesting topic.|
I have a "factory" GTV8 which I have owned since 1973, and which now has a 220 bhp Jon Eales engine and an R380 gearbox, but no LSD. The rear end is standard except Konis and springs uprated 25%, spring clips welded closed, and poly bushes.
Just over a month a go I purchased a low mileage RV8. As yet I have only covered a thousand miles in it.
There are other interesting comparisons, but, with difficulty, confining myself to this thread I will concentrate I will comment on the rear end only.
My feeling, and I am not an engineer, is that the handling of the BGTV8 with no LSD is superior, and certainly instills more confidence.
In the BGTV8 if I encounter an unexpected problem, or put the power down a little too early exiting a corner, the back end will break away, but is easily corrected. Under certain circumstances I may decide to drift through a corner "steering with the throttle", or induce a full rear end break away.
With the LSD in the RV8 I cannot drift the car, it hops and dances around, and I cannot safely on the roads induce a rear end break away.
Under hard acceleration the delivery of power to the rear wheels seems to switch from wheel to wheel, again inducing a "weaving" feeling, which certainly does not inspire confidence.
I have yet to make a decision, but have discussed this with one other RV8 owner who also has a BV8. We are both considering investigating how easy it would be to remove the LSD and revert to a conventional differential.
If you do decide to change to an LSD I suggest you try a car with the LSD in question, preferably for a reasonable mileage before you commit yourself.
Final comment. The RV8 has some shortcomings, and it is interesting to compare it with a sorted BV8. I am am delighted with both my V8s, but believe that the standard RV8 is capable of improvement.
That's an interesting post. Surprises me greatly, but interesting. One thing you'll be happy to find is that it's not a big deal to swap in a conventional diff -- don't have to pull out the pinion or anything -- in fact you'll probably find folks foaming at the mouth to do a swap with you. (Of course any work on the rear end internals is almost certainly best handled by a specialist -- not at all likely a backyard mechanic is going to set it up correctly.) Anyway, I wish you were in the U.S.! I believe that you will see that, weaving or not, the LSD is putting power to the ground much better (you won't find yourself chirping one wheel while the other just sits there), and your acceleration times should _certainly_ -- beyond a shadow of a doubt -- be better.
|So, for those of you who are using a T5 with the stock B axle (1:3.9), what does 1st gear top out on for you? 10 mph? 15? 20? I'm curious because I'm getting to the point right now that I'm going to be buying parts. I was going to go with an 8" ford rear, but now I'm not sure.|
I have been using a rear end with 3.23 gears and limited slip for 17 years now. I am very pleased with it. The gear ratio seems just right for the T5.
The stock MGB (a pre emissions one) will break the right rear tire loose. The way that I look at it, why put a V8 in it unless you can use ALL that wonderful power!!! I have not had any handling problems because of the limited slip. If the clutch pack is properly set up it should not cause any problems, and you'll love the traction when you "stand on it"!
|I've raced for four and a half years without and one and a half years with a quaife LSD and have to say that it feels more predictable with the LSD.|
I've driven an RV8 once for about 20 miles with the owner in the passenger seat and after making the diff work once he commented that it was not working properly and needed looking at - and he co-owner an MG dealership! Apparently the RV8 unit was sourced from ?Maserati, if I had the money to buy an RV8 and what I experienced was typical I'd change to a quaife unit.
|After running my factory GTV8 for 2 years with the standard 3.07:1 rear, I fitted a Quafe LSD and the improvement I thought was quite stunning. The handling while accelerating is much more pradictable.|
I also had composite springs fitted. Maybe the two work well together.
This thread was discussed between 25/01/2001 and 28/01/2001
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