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MG MGB GT V8 Factory Originals Technical - Rearend Opinions
|Anyone have any inputs on having a rearend fabricated? I am considering using Currie Enterprises to build me a narrowed 8" Ford posi unit with 3.55 gears and drums and then fitting that with wire wheel hubs redrilled to the Ford pattern.|
My requirements are that the rear be bulletproof and be set up for wire wheels; I don't need high speed, but rather want a "quick" car.
Anyone use Currie? Any feedback is appreciated.
|Yes, Currie is the best when it comes to narrow rear ends. They sell a economy set of axles for around $325|
and they work great. The 8" rear has taper axles and can not be respline, unless they are cut more than 4" on each side.
Two things to consider when swaping rear ends:
1) Have it narrow so that bigger wheels and tires can be use. Stock size for wire wheels I believe it's 51" and 52" for disc wheel.
2) Wheel cylenders are bigger on the Ford, try to match the size for the correct brake bias. Another option is to install a proportioning valve (Tilton, Wilwood) Remember that when you apply the brakes weight is tranfer to the front, rear wheels become lighter, with bigger cylenders, tires would lose traction.....and longer distance to stop the car.
You want the fronts to get must of the fluid pressure and force on the pads.
What engine are you going to use?
r/ Bill G.
|Has anyone tried using a Datsun/Nissan 280Z IRS in an MG? Also how hard is it to shorten the Jag half shafts..I have heard they are near impossible to shrten as they are billetted steel. Any comments?|
Thanks for the inputs. Did you have Currie build your rearend?
I am installing a 215 Buick that has been lightly massaged; I am aiming for approx 200 hp. The widest wire wheels available seem to be a 72 spoke 15X6", so I thought that I would go for 2 inches narrower than stock or 49 inches.
I had planned on a proportioning valve to make up for the wheel cylinder size difference, thanks for the inputs.
|Erich, I had currie built a few for me, one for a 40 Ford with a 454 chev. it was a 9" Ford Posi etc.|
and 8" for a few MG's and other cars with various types of engine engines. The 8" is very strong and great for swapts becouse of their size and has all the benefits of the 9" rear end. It is limited in ratios (355 to 411)The 8" is good for 300 hp with the econo axles. (check with Currie) Wire wheels can be made custom (British Wire Wheel, Lots of $$$$) 6" wheel is plenty for the B chassis You could mount a set of 215X60X15 BFG This tires are good for 5.5" to 7" wheel 6" wheel is perfect, the thread would be even with the wheel lip, thus making the side wall of the tire stiffer, the result less flex of side wall translates into better traction and overall better handling, or a set of shorter tires like 205, 195
Great idea Erich, narrow 8" Ford rear with whire wheels and V8. Please send picture when finish or if you are in southern Ca. lets meet, I really would like to see your car.
r/ Bill G.
|Mark, I have used the Jag rears. Axles are driveshafts and cost around $150 each to shorten. Alots of pros and cons in installing a Jag rear on any car.|
Rear independant Suspension requires alignment just like the fronts; Toe, Camber, caster is 0. This settings are critical specially on a small car (short wheel base) It could be whild at speed cornering if not set up right. eg; If you have neg camber on the rear then it must be compensated with Pos. camber at front, this also affects braking.
There is a gentleman in the UK who is working on a Jag set up for his B, he is also installing the front end of the jag. his name is Nick, I could get his e-mail address for you.
Anything is possible Mark, it just requires good planning. I think Nick is on the Web page of V8 convertions, He is the same person who added strengh bars to the B.
I had investigated the Jag rearend and the best deal seemed to be at Concours West Industries in Costa Mesa, CA. I can't seem to find their phone number, but they have custom widths and also sell used rearends, and would be the first place I'd start.
I gave up on the Jag rear first because of cost, but also because of the need to fabricate a cradle support and frankly it was a little daunting to me to try to figure out how to align it all. The Ford solution seemed more my speed. Check out http://www.v8mgbgt.demon.co.uk/ - there are some pictures of his installation and I'm sure Nick can provide lots of advice.
|Ford rear ends are probably quite cheap in the US, but another excellent option if you are staying with live axle is a Volvo rear end. Like Volvo cars, the rear ends are built strong (with a capital S). They are very cheap because Volvos never need new rear ends, there is a wide choice of ratios, albeit not as wide as Ford and they have disc brakes. |
The guy who narrowed my Volvo rear end laughed when I phoned him for a quote. He stopped laughing very quickly whn he saw how strong it was. The half shafts are huge!
In the UK, where Ford 9" rears are qquite expensive, many drag racers are using Volvo.
Some food for thought, but don't tell too many people other wise the wreckers might start charging for them rather than almost paying people to take them away.
|David, your suggestion is very interesting to me.|
Please supply us with more information, I am always trying something new.
What ratios options does the Volvo differential have?
What adjustments did you have to make to the brake bias?
How much did had to narrow the differential?
What model of Volvo?
Is the differential a Banjo or Tube type?
How much hp can it take?
Great input David.
|Do either the Volvo or the Ford 8" have a removeable carrier like Ford 9"?|
|I have a 240 Volvo from the 80's and am very impressed with Volvo's durability, so am considering this axle for my V6 conversion. The Volvo gearset is a Dana 30 type, which is not that common. Ratios in my factory manuals are 3.31/3.54/3.73/3.91. (I believe those first two ratios are only found on a manual trans car.) They are a tube-type and closely resemble the MGB. They are about 8cm or 3-inches wider than the B (wheel mounting surfaces) and have disk brakes (11-inch dia. and made by either Girling or ATE) with a small integral drum each side for the handbrake.|
Volvo's rear suspension on the 240's (your most likely source of axles) uses trailing arms with coil springs, torque rods, and a Panhard rod. Thus there is a lot of bracketry that will have to be cut or ground off and replaced with B hardware.
A company making parts for Chev V8 conversions into 240 Volvo's declare the axle to be plenty strong enough for this engine with its 300+ lb-ft of torque. (see www.jagsthatrun.com)
|Bob, thank you for the info.|
Do you know if the axles are taper. If they are not, it would be very economical to use on a B. They are plenty of Volvos's around.
The cost to comvert would be around $300 plus the cost of the axle, this estimate is a bit high. Vs the cost of a 8" around $500 to $600.
Great info Bob.
Regards Bill G.
|Bill: David in Melbourne has apparently had the axle assembly narrowed and could comment on half-shaft type. My shop manuals don't show a clear picture of the half shafts. What they do show is that you should make sure you get a good unit, as the diff. disassemble-and-rebuild process is extremely complex looking and requires a lot of special tools. Contrary to my earlier posting, there is a reference to LSD's, but I was in my Volvo dealer's service dept today and the head guy said "hen's teeth - mostly used in Swedish police cars". If you can find one of those - great.|
You want the 3.31 ratio for a torquey engine in the light MGB, and this means look for a 1980's 240-series car with the non-Turbo 4-cyl (turbo's were 3.73) and a manual box, or a diesel/automatic. The axle should have an ID plate affixed to the left side tube forward edge, just next to the diff case, which gives several numbers, one of which will be easily recognizable as the CW/P ratio. BTW, all 3.31 ratio axles are Volvo's "heavy duty" version.
I have been off the air for a couple of days. I agree with all that Bob says. I have a 3.54 ratio, this might be a little short but will give good acceleration for hill climbs and sprints. The half shafts do not taper so they are easy to cut down and re-spline.
Off hand I cannot remember exactly how much I had it shortened by, it was around 1 1/2 inch on each side. Here in Australia it cost the equivelant of around US$100.
Grinding the bracketry off was very easy as was welding on the new ones.
I have not worked out my brake bias yet because I am still to decide on what I put on the front.
Here is Australia, we have a lot off 3.31 and 3.54s.
I heard the other day of a Volvo Wreckers who were throwing out Volvo rear-ends because they never sell!! Most of the guys here in Australia only think Ford 9" when they think of a conversion.
One more thing that I forgot to mention is that the axle tube of the Volvo are the same diameter as those on an MGB rear end. This makes it relatively simple to change over.
The hubs can be easily redrilled for the MGB stud pattern. I have used Saab 99 studs in mine. They were the right length and I was really surprised to find that they were the same thread as the MGB.
Regarding LSDs, these were used a lot in the station wagons sold in Scandinavia. They were often called snow wagons. The raindeer farmer's favorite. My source tells me that they really are not as rare as first thought. I also believe that the 240 GT has a LSD fitted as standard in some markets.
I actually paid for my rear end, it cost me A$50 (~US$35). I am sure that you would have trouble picking up a Ford 9" for that sort of money.
|I have been researching using the rear axle from a Jeep which is 50.5" wide so would not require narrowing. Lots of information can be found at "www.off-road.com/jeep/tech/AxleGeneral."|
The best axle for the MG appears to be the Dana 44 and you can find info about it at the same web site. I e-mailed an outfit called Harveysjeep and got a quote on the Dana 44 with a centered differential, 30 spline single shaft and they have it in stock used and rebuilt for $1050 plus shipping with no exchange and one year warranty. Seems about the same price as finding a used Ford 8" and narrowing it down.
|David (Melbourne) said:- "....... I have used Saab 99 studs in mine. They were the right length and I was really surprised to find that they were the same thread as the MGB."|
Don't forget that the space-saver spare from a SAAB 900 (1980 onwards) is often used a s a space-saver spare in the V8 wheelwell, and one reason it's suitable is because the stud threads are the same.......
|Thanks for the info. I went to a boneyard and found several Volvos and Saabs. The cost for a complete axle is around $100 to $150. To narrow the housing will cost $80 to re-spline the axles $150 to re-drilled the hubs to MG pattern $50 and then we have the cost of the brakes etc. This axle is cheaper than a Ford 8" and stronger (According to some of you) I went to a Volvo dealership and ask them about Posi traction set up, apperantly this are rare in the US.|
This axle is cheaper than the original MGB It is a great replacement unit. David mention that the axle tubes were the same dia. This makes the axle easier to install on the MG it's about $40 savings (U bolts etc.)
I also look at the front brakes, these look great.
I wonder if anyone has used them on a B. If they were use on a B then the proportioning valve from the Volvo and maybe the master cylinder could be use OH... well just thinking aloud. Anything is possible.
Great info in this section, thanks Bill G.
|Bill we use the ventilated disc from a Volvo turbo as a brake conversion in the UK. For calipers we use something thats not available in the USA - Austin Princess/Ambassador 4 pot units suitably shimmed. If you are interested I can put you in touch with the specialist brake outfit in England I got them from. All in all they only cost me $450 delivered and they do a great job. Drop me an e-mail if you want the name and tel number.|
|I just bought an axle out of a postal jeep (AN General)for my upcoming MGB V8. $75 at the local wrecking yard. 3.08 ratio, limited slip, right width. So far; Rover SD1 3.5, $325 (inc. bellhousing); SD1 5-speed, $400; jeep axle. $75...|
|Whilst moving shop last year I found some of our old stock (NOS)3.07:1 CWP sets we had made for the MGBV8 axle conversions, from memory we have about 16-18 units left, these were designed to go into the B rear end with very little machining to the carrier, although more expensive than a old scrap yard axle at least everything else is the same and no hassle to fit or get spare parts, these sets are 300GBPplus shipping . Maybe this can solve the problem of which rear end to use,regards mike.|
|I've had a few Volvos and like them much. My old 245 wagon was like a tractor and would pass stranded Jeeps on the way up the ski hill (probably just over confident drivers). I don't remember any of them whining (Volvos that is) even in reverse. 3.31:1 sounds a good all rounder with T-5 .65 final drive trans. Anybody have front and rear slave cylinder diameters handy? It would be nice to retain the MG master. Incidently, know where one might find a ?Bendix? remote servo in NA and are they suitable for LHD?|
|Guys, can anyone tell me what the standard rear track of the 240/260 series volvo is?|
|Volvo give the rear track in the factory shop manual as 136cm. The MGB is 125cm for a difference of 11cm or 4.3 inches. But "track" is a dimension I don't understand well. It looks on the diagrams I've seen that track is the distance between the centres of the tire contact patches, which should also be the centrelines of the rims. But it's not the distance between the brake drum/hub surfaces where the wheels bolt up, as wheel offset becomes involved in that issue. |
My 240 Volvo has 22mm offset, my Rostyles have 29mm. I measured the distance between wheel mtg. surfaces on my Volvo and '71GT and believe I came up with the Volvo being somewhat more than 3-in. wider. It's late, I'm tired, and someone else can do the math and see if this all goes 'round, but it seems the greater positive offset of the Rostyles would require LESS narrowing of the Volvo rear than the "track" dimension suggests.
(Yawn)...OK, I did the math and it says that the Volvo axle would have to be narrowed 3.78inches to place a set of Rostyles the same distance apart as the MG axle. Before narrowing any axle, recall the numerous comments here about std MGB axles not being properly centred under the car and tires rubbing the wheel arches. Custom narrowing of an axle gives you a chance to correct that if it affects your car.
|What about the bolt pattern on the Volvo axle? I know it is four bolt like the MG, will the MG wheel bolt to the Volvo axle?|
|Not so. Volvo = 5 X 108mm. MGB = 4 X 4.5 inches. Must redrill Volvo hubs. See Bill Guzman's post above ($50 to redrill to MG pattern.)|
|I have a Ford 8.8 axle question. I have a rubber bumper MGB with fiberglass rear springs at the chrome bumper ride height. I am interested in what angle is being used on these Ford rear axles between the spring seat and the axle pinion when used on an MGB V8. My MGB has a Rover 4.6L engine. I believe the std MGB is set at about 3 degrees. Any comments on other rear axles would be appreciated also! Is there an optimum angle?|
Regards, Jack Think Spring! :-)
|Driveline theory says the rear axle pinion shaft and the gearbox output shaft must be parallel to each other. Not co-linear, just the same number of degrees from horizontal. In this way the slight speed changes in the shaft caused by the geometry of the U-joints are self cancelling and this form of vibration is avoided. |
The mass of the shaft and yokes must still be dynamically balanced.
If you are doing an engine conversion, it's possible that the gearbox/engine assembly are being hung in the chassis at a different angle than the original, and the factory std. rear axle pinion angle may no longer be correct, and should not be a pattern for your new axle.
Some engine conversion guides recommend using an inclinometer to measure these angles, and then use wedge shims in the spring mounts to get things aligned. If a custom axle assembly is being welded up, you have an opportunity to get the spring mounts precisely aligned and welded for a no-maintenance, permanent setting.
|Has anyone had any experience or know anything about Trevor Taylor's (of Trevor Taylor Conversions, Surrey)indep. rear coil-over set up. Some interesting pics at his site. There's a front coil-over set up also. Discs all around. Angus|
I e-mailed Trever earlier with the same question. The rear suspension bolts in to the original suspension/shock absorber mountings. It has a Ford Sierra,Granada,Cosworth differential available with many different ratios and limited slip. and it's fully adjustable. The price hasn't been set because it's not out yet. It will be presented on the 20th of February in Trever's own MGB. -I can't wait either.
The front clip is not out of an RV8. It is Trever's own design, also fully adjustable. Your crossmember will have to be modified to accept the full size spring and shocker- which he supplies a plate to do this with. The price is 650pounds plusVAT.
E-mail Trevor for more information.
Hope this has been a help to you.
I've submitted several questions to Trevor. Hopefully he'll get back to me Monday. You've answered a few already. The rear mounting I'd guessed at from the pics. Kinda cool! Ouch on the proposed price, though... I'm a little dissapointed that I'll have to wait for a 'biased' opinion or for the bugs to be worked out. It sure looks interesting in photos though. I wonder how the set up goes. My '71 GT is still in the "accident repair and rust removal" stage with an already modded X-member, so what the heck! I want big brakes too.
|I've just been through the archives on brakes again and came accross the L&A "disaggreement". Yipes! Anyhow, I hadn't realised that the remote servo used in the UK in the 70's was for a single circuit system. I'm not yet disabled and I kinda like the effortfull progressive 'umph' required to gradually bring the wheels to lockup. Can I do without a servo with big front brakes (Princess/Ambassadore four pots) in a dual line? I squat 400 lbs just for fun, wheeeeeze. It's that darned cooshy toyota corola that pops my eyeballs when I sneeze if my foot is even remotely in the vicinity of the brake pedal, isn't it. Can anyone save me a trip to my local wrecker's(100 miles) and tell me what minor bulkhead mods are needed to fit late-type integral master and servo to an earlier shell? Have '71 and a big knife- need ?'75+. I could manage myself, but... |
The above was supposed to be in 'front brakes'.
|Almost nothing. I put a US Spec servo/mast cyl.and pedal box assy, from a 78 Roadster on a late 74 GT when I was doing my first V8 conversion about 15 years ago..I may have had to drill the odd hole, that's all!|
|My memory may be fading with the years, but didn't Ford put an 8" rear in the old Maverick with 4 lug 4.5" pattern axles? One of these would eliminate the cost of redrilling the axles and brake drums and you could get replacement parts 'off the shelf'. I think these were also used in 6 cylinder Mustangs.|
You are correct on the 4 x 4.5 inch hubs on some 8 inch Ford rear ends. I used one from a six banger Comet in my TD. I didn't shorten the axles, just used MGA wheel center sections with 6 inch rims welded on with most of the offset to the outside.
This thread was discussed between 23/12/1999 and 07/02/2000
This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.