Engine and Transmission Tech

tips, technology, tools and techniques related to vehicle driveline components

Go to Thread: PreviousNext
Go to: Forum ListMessage ListNew TopicLog In


Brownwood
Keith Montague

(176 posts)

Registered:
01/25/2014 08:08PM

Main British Car:


Blitz Speed Limited Slip
Posted by: Brownwood
Date: February 12, 2015 12:35PM

OK, I have spent a fortune on a driveshaft, wheels and tires etc. on my 5.0 V8 MGB. I always intended to upgrade to an S10 rear but now I re-thinking. because I have a significant investment in my stock 1980 MGB rear and because I understand it is plenty strong; I am beginning to think about installing a LSD from Blitz Speed in Britain. It is about $1100 and would just bolt in to my ring gear while converting to an S10 rear would probably cost at least that much along with a lot of fabrication and installation pain.

Since Ive never seen anyone here do this, I am wondering if I am missing something?


MGBV8
Carl Floyd
Kingsport, TN
(4042 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB, Buick 215

authors avatar
Re: Blitz Speed Limited Slip
Posted by: MGBV8
Date: February 12, 2015 01:15PM

Hmm.

[www.ebay.com]

Biggest issue is the limited selection (& expense) of gear ratios for the stock rear to go with this expensive posi.


Brownwood
Keith Montague

(176 posts)

Registered:
01/25/2014 08:08PM

Main British Car:


Re: Blitz Speed Limited Slip
Posted by: Brownwood
Date: February 12, 2015 01:38PM

Hmm, I love my 3.90s for blasting around town and with the T5 I run about 2400RPM at 70, so maybe for me this is a good choice?

S10 3.73 rear $250
Posi unit $400
Redrill of axles $150
New driveshaft $400 plus losing $400 on the one I have now.
Total: $1200 plus pain and suffering.


billymgb1000
bill gaulin
harrisville R.I.
(74 posts)

Registered:
11/30/2012 12:31AM

Main British Car:
1974 MGB V8 LS1 5.3

Re: Blitz Speed Limited Slip
Posted by: billymgb1000
Date: February 12, 2015 05:02PM

Hello Keith
I am running a ls series 4.8 with about 340 hp. your motor is probably doing about the same, well I went through 2 stock rear ends and I wasn't beating the crap out of them either. I had read they could handle it but let me tell you THEY CAN'T. I just wanted to tell you cause I hate to see you spend that money and still have to do the s10 rear down the road. yea it's a pain in the but to install but once you do it your done. I went with a 69 ford fairlane 8 inch I had to narrow it and I did all that work not to bad then I ordered new axles with the correct lug pattern. I also have good money in my rims and tires too. when the first rear blew I figured I had one that was going to blow anyway, so I had another one from stripping a parts car and put all new seals new oil and gasket. after that had happened I babied this rear even more than the first one, after about 3 months taking a left got going and layed in to it at about 30 I heard clunk looked in the rear view and saw the dreaded oil trail luckily I was close to home so that is why I'm saying save your self time and money
100_1593.JPG


JWD
Jim Durham
Gig Harbor, Wa.
(103 posts)

Registered:
01/22/2013 11:43AM

Main British Car:
1980 MGB Ford 302 (398.9 HP, 383.2 TQ)

Re: Blitz Speed Limited Slip
Posted by: JWD
Date: February 12, 2015 05:26PM

Keith,

I think your numbers are off. I just installed a new rear in mine for a lot less.

GM 10 bolt, 3:42 rear with posi and disc brakes - $200 (It came out of a wrecked Blazer with only 15K miles)
Moser axles drilled to any pattern you want $300
Driveshaft - $200 including yoke and u-joints
Narrow housing - $125



Edited 1 time(s). Last edit at 02/12/2015 05:30PM by JWD.


Brownwood
Keith Montague

(176 posts)

Registered:
01/25/2014 08:08PM

Main British Car:


Re: Blitz Speed Limited Slip
Posted by: Brownwood
Date: February 12, 2015 05:38PM

OK Jim and Bill, you are compelling.

Also, with my fender flares, if I can find a 3.73 posi from a 2WD S10, I dont have to narrow it as 54 inches is ideal with my current wheel and tire combo. I would rather have 3.73s over the more common 3.42 and that's where I have had problems as apparently a 4x2 373 posi is a rare bird.

I think I will continue hunting for the S10 rear though. Thanks all!


JWD
Jim Durham
Gig Harbor, Wa.
(103 posts)

Registered:
01/22/2013 11:43AM

Main British Car:
1980 MGB Ford 302 (398.9 HP, 383.2 TQ)

Re: Blitz Speed Limited Slip
Posted by: JWD
Date: February 12, 2015 05:59PM

"I would rather have 3.73s over the more common 3.42 and that's where I have had problems as apparently a 4x2 373 posi is a rare bird. "

I don't know where you live but here in the Pacific Northwest, 3.73 posi rears are everywhere. I specifically wanted 3:42, posi with disc brakes and 75% of the rears I called on were 3:73 posi's and the rest were 3.42 non posi with drum brakes. I bought the first one that met my criteria and it took almost a year of looking. I almost gave up and went with 3.73's but with a 2.95 1st gear, I'd be shifting to 2nd before I got out of the intersection.



BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6008 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Blitz Speed Limited Slip
Posted by: BlownMGB-V8
Date: February 12, 2015 07:54PM

The stock axle is good for up to about 300 Hp, depending on how you drive it. But bear in mind, the stock Salisbury has about an 8" ring gear. It's debatable if the 8" Ford R&P is any stronger. (disregarding spiders and axle shafts) I wore out a stock axle myself (had spares) and it was the R&P that went. My theory is that it's the part that sees the highest loads during freeway acceleration. For a higher powered car I wouldn't consider a ring diameter of under 8-1/4". I'm aware that many owners are satisfied with the 8" Ford, but at power levels over 300 Hp it should realistically be considered marginal.

A 9" or an 8.8" are really both overkill and add a lot of unsprung weight. That leaves us with a limited number of choices. The S-10 uses a 7.6" ring I believe, so it is a step backwards and I do not understand why anyone would use it in an MGB with a V8 engine. That pretty much leaves us with the Dana 44 at 8.4", the Mopar at 8.3" and and the early 10 bolt Chevy at 8.5". If you want your axle to stand up to those power levels and still not be any heavier than it has to be those are the places to start looking.

Incidentally, the reason Ford no longer uses the 8" and 9" axles is because the higher helix angle is less efficient. The difference could be as high as 5%.

Jim


JWD
Jim Durham
Gig Harbor, Wa.
(103 posts)

Registered:
01/22/2013 11:43AM

Main British Car:
1980 MGB Ford 302 (398.9 HP, 383.2 TQ)

Re: Blitz Speed Limited Slip
Posted by: JWD
Date: February 12, 2015 08:09PM

"The S-10 uses a 7.6" ring I believe, so it is a step backwards and I do not understand why anyone would use it in an MGB with a V8 engine."

Talk to someone that ACTUALLY uses them. It's the same rear end that's in the mid 80's F-body Camaros & Firebirds which is a much heavier car with a V-8. The only issues they have are at the track running drag radials or slicks. With a few modifications, it can handle 400-500 HP in a 3500 car. In a MGB, it's basically bulletproof.



Edited 1 time(s). Last edit at 02/12/2015 08:12PM by JWD.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6008 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Blitz Speed Limited Slip
Posted by: BlownMGB-V8
Date: February 13, 2015 10:58AM

You may be right but as far as I'm concerned the jury is still out. Basic metallurgy hasn't changed enough in the last 50 years to account for that much difference.

In high gear at freeway speeds the weight of the car is immaterial in determining instantaneous loads on the ring gear. The relevant factor is engine torque alone.

I stand behind my statements.

Jim


MGBV8
Carl Floyd
Kingsport, TN
(4042 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB, Buick 215

authors avatar
Re: Blitz Speed Limited Slip
Posted by: MGBV8
Date: February 13, 2015 12:53PM

The early Chevy 10 bolt was 8.2" as came in my '68 Camaro. The 8.5" 10 bolt, also known as the Corporate 10 bolt, was phased in in 1971 to replace the smaller 10 bolt & the 12 bolt.

The Austrailian 9 bolt is 7.75", but is quite stout. A friend had a third gen Camaro, 305 V8 with a centrifical supercharger. He drove it hard in the mountains of NC & bracket raced it (on street tires). The 9 bolt held up.

That S10 rear is pretty good for most MG conversions. Mike Moor says that his is a 7.625 S10 with Auburn cone posi. It has been living for years behind his Buick 300 that was dyno'd at just over 300hp to the wheels.



Edited 1 time(s). Last edit at 02/13/2015 07:32PM by MGBV8.


Sorry, only registered users may post in this forum.