danmas Dan Masters Alcoa, Tennessee (578 posts) Registered: 10/28/2007 12:11AM Main British Car: 1974 MGBGT Ford 302 |
Re: Which rear end for 400bhp MGB
Quote: I have one of those. I'm only putting down less than 350HP, so I should be good to go. That's good news, because you guys were starting to scare me. |
74ls1tr6 Calvin Grannis Elk Grove,CA (1151 posts) Registered: 11/10/2007 10:05AM Main British Car: 74 TR6 / 71 MGB GT TR6/Ls1 71 MGB GT/Ls1 |
Re: Which rear end for 400bhp MGB
Carl said:
Quote: In the Miata/Ls1,2,and 3 world they prefer to use the Ford 7.5" rear end. Again they said the car is light enough to use with the swaps. the 8" is to big for clearance issues in Miata applications. Just a thought! Same issue with the R200's in the drifting cars, said to be good for 550lbs of torque. In that application it would be the stub axles are the week link. Just my thoughts, a 3500lb car and up would be looking closer to the 8.8" or 9" ring and pinion, and the 400hp in front of them. Of coarse I'm talking normal and spirited driving with no clutch dumping. We all can spin the tires with out cars fairly easy! |
74ls1tr6 Calvin Grannis Elk Grove,CA (1151 posts) Registered: 11/10/2007 10:05AM Main British Car: 74 TR6 / 71 MGB GT TR6/Ls1 71 MGB GT/Ls1 |
Re: Which rear end for 400bhp MGB
Quote: They are normally 28 spline axles. I was talking to Ted and asked him about 400+ torque with his 8", he said you can go with the 32 spline axles and gears. I said I'll go for the 32 splined axles and spider gears. I'm also running 3.54.1 because of 6 speed T56. Edited 1 time(s). Last edit at 01/27/2014 10:39PM by 74ls1tr6. |
mgb260 Jim Nichols Sequim,WA (2461 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Which rear end for 400bhp MGB
The 8" is right between the 7.5 and 8.8 in strength. Calvin is right on the lighter car being traction limited anyway. Carl's 300HP limit or use the 7.5 for 4 cyl,V6 or 215/3.5 V8. The 8" is perfect for 300 to a little over 400HP. Actually Torque is a better number. That is what breaks things The 8.8 if built right, is right up there with the Dana 44 and 9", should be good for 500HP. The 31 spline axles are larger diameter and stronger. For racing, I think the Dana 44 or 8.8 would be the answer.
Edited 1 time(s). Last edit at 01/28/2014 06:08AM by mgb260. |
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TXS67BGT jay musgrove low country (15 posts) Registered: 11/16/2008 10:12AM Main British Car: 1967 MGB GT 1998 LS1 |
Re: Which rear end for 400bhp MGB
just to add another option in the mix, and Jim Nichols I hope you chime in here, I bought a rearend from a wrecked 98 Camaro Z28, 3.43:1 with disks, Eaton posi, seemed at the time to be just what I wanted, during the rebuild bought new bearings, clutch disks everything I thought I would need. the bearings for a 7.5 did not fit, after digging around with the local Chevy Parts guy he showed me that it was a 7 5/8, only two ratios available, ordered the bearings for that and they fit. Local (Kent Washington at the time) rearend specialist did the cutting and welding said he had seen only one other 7 5/8, said the tube walls were thicker than the standard 7.5. now all this is from memory, thought at the time I was rather lucky to run across it, hope all I have said is correct, do know it had Aussie aluminum calipers. The shop I bought it from had it in a car they had been drag racing with, behind a 415HP LS1 and it held up fine behind an 4L60E trans.
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MGBV8 Carl Floyd Kingsport, TN (4511 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: Which rear end for 400bhp MGB
How many bolts holding on the cover, 9 or 10? Sounds like it could be an Australian 9 Bolt.
They are actually pretty stout. A friend of mine had a Third Gen Camaro with one. It survived his Paxton centrifugal blower equipped engine & a 5 speed. Great info: [www.thirdgen.org] Edited 1 time(s). Last edit at 01/28/2014 12:41PM by MGBV8. |
mgb260 Jim Nichols Sequim,WA (2461 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Which rear end for 400bhp MGB
Hey Jay, GM 10 bolts after about 89 or so went to 7.625 ring gear and 28 spline axles. If I remember correctly,even the rear cover and outer bearings were the same as the earlier 7.5. The Australian 9 bolt was used in higher performance Camaro/Firebird. That rear cover looks more like a Dana and no C clips, also 7.75 ring gear. Another option for a narrow rear is the 89-92 GM S10 2WD. It is 54"wide and if you cut 1" off splined ends to eliminate C clips, narrow tubes and use Ford bearing ends comes out 52" same as stock MGB. 4.75" Chevy wheel lug pattern.
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waterbucket Philip Waterman England (112 posts) Registered: 07/30/2011 01:08PM Main British Car: 1972 MGB GT |
Re: Which rear end for 400bhp MGB
There is another axle available in the UK, the one from the Reliant Scimitar SE5. I think I am right in saying that it is only 11/2 inches wider than the original B axle, it has the brackets already for a four link location and a Watts linkage for lateral location. It takes Jaguar diffs (or Dana 44) so plenty of choice there for ratios and lsd. I guess it might be lighter than the Land Rover axle.
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Re: Which rear end for 400bhp MGB
Thanks everyone.
looking at the photos some have mounted the shocks just in front and some just behind the axle. The ford escort coil over kits mount the shocks on top of the axle. Is this as a result of packaging or is there an optimum position. I have room to fit them on top of the axle or just in front. Which would be best? Cheers Mark |
Moderator Curtis Jacobson Portland Oregon (4576 posts) Registered: 10/12/2007 02:16AM Main British Car: 71 MGBGT, Buick 215 |
Re: Which rear end for 400bhp MGB
Putting the shocks in front of the axle leaves room for a Panhard rod or Watts linkage between the axle and fuel tank.
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TXS67BGT jay musgrove low country (15 posts) Registered: 11/16/2008 10:12AM Main British Car: 1967 MGB GT 1998 LS1 |
Re: Which rear end for 400bhp MGB
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mgb260 Jim Nichols Sequim,WA (2461 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Which rear end for 400bhp MGB
Jay, Nice looking setup. It'll be a smooth ride. Did you center or use aftermarket fuel tank? Curtis is right on front mount shocks/rear panhard , not a lot of room between the rear axle and tank . Triangulated like Jay and Graham have can be mounted either way. V8bloke(Mark) any progress pics?
Edited 1 time(s). Last edit at 02/13/2014 10:54PM by mgb260. |
roverman Art Gertz Winchester, CA. (3188 posts) Registered: 04/24/2009 11:02AM Main British Car: 74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L |
Re: Which rear end for 400bhp MGB
Mark, We are about "sharing", beneficial knowlegde-here. How about you tell us all about your TA headed, RV8 build ? You have not mentioned, if you will need different r & p ratios, for different circuits. If so,IMHO, you'll definately want a drop-out center section.Servicing a drop-out, on a bench, sure beats an "integral", in the car. Are you drag racing or road racing ? Drag slicks and drag tuned suspension, will shock-load a chosen rear, to the max. There are items to counter-act this. 8" Fords have 31 spline axles available, even hollow , lightweight full floater set-ups. 4 spider limited slip units, including gear only.What will be the r & p ratio, as this affects strength. More teeth in contact + stronger. Maybe a ring gear "thrust button", like 9 inchers use ? "Soft-lock" clutches, are available. Perhaps a rubber coupled drive shaft ? Good Luck, Now tell us, about your RV8. roverman.
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Re: Which rear end for 400bhp MGB
Thanks guys,
modifications are progressing at a very slow pace. Will post pics soon. Rather than work around the existing metalwork I have chopped out everything between the chassis rails inc most of the boot floor up as far as the rear seat kick panel. I seem to spend a lot of time just looking at it with arms crossed trying to figure out the best way forward. The brackets for the Mumford linkage are made and am waiting for billet ally bell cranks to be made. I will be using an MGB axle with stronger shafts for now but have made sure there is room to swap to a larger rear end if needed. At the moment I am making and welding on all the housing brackets for upper and lower trailing links, mumford links and anti roll bar. I am still not decided exactly where I will be mounting the coil overs but it is likely to be behind the axle as the mumford link brackets will double up for mounting them. Also I am having an aluminium fuel cell made that will fit upright with a built in swirl pot and baffles. Although the car is road legal it is mainly used for track days and is stripped out so I am not at all worried about originality. Will post some pics soon. Mark |