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MG MGB GT V8 Factory Originals Technical - Idea for IRS

I've been researching the mid 80's to 90's Volvo Multi-link IRS found in 700/900 series sedans. It is a Dana 30 and the Turbo models in the early 90's used an Eaton Gov-Loc Locker. The Jeep Power-Loc 4 pinion clutch type Limited Slip and True-Track gear type also fit.It has faborable ratios also: 3.31,3.54,3.73. It would have to be narrowed.I was thinking custom subframe and tubular control arms,coilover shocks.300Zx Turbo CV axles with adapters or redrilling of flanges. Or there is a few places that make custom length axles. What do you guys think. It is the same as the Sierra/Merkur diff and should be perfect for V6 or small V8 power up to 300HP. Maybe more if an automatic is used and you don't drag race.The wheel stud pattern is 5 X 108.I would have the hubs redrilled to 5 X 114.3(Ford 5 x 4.5").
JN Jim

Hi Jim,

I've been looking at a few different IRS options. Aside from the Hoyle one (which is cost prohibitive in the US (IMO)), i've not found any that enable the exhaust to be routed through the IRS somewhere rather than under it. You might want to give the routing some thought before you get too far down the path.

Good luck & post some updates if your pursue it further. I'm still keeping my eyes out for an affordable IRS option.

Rob
rficalora

Don't forget you are also likly to make the back end quite a bit heavier. The moment the weather warms up a bit I'm putting in three trailing arms and coil springs. A three link (plus pan hard, 4 really) a little like the current mustang or the old C type Jags. It should end up a bit lighter than the current set up.
However having said that, check the archive
Peter

"Don't forget you are also likly to make the back end quite a bit heavier."

Perhaps, but you should also be making the unsprung weight significantly less. That is a good trade off.
Dan Masters

Peter,I doubt if it would be much heavier if at all. I plan a tubular cradle with tubular control arms and cv axles. The diff housing is aluminum.The stock steel subframe would be heavy. The Volvo solid axle has the suspension you plan but is wider than MGB. Rick,the diff in the Volvo is the same as the Sierra diff Hoyle uses(Dana 30 ;7 3/4" ring gear). The Hoyle IRS is popular in the Hawk Cobra replicas in England. It seems to hold up well to small block Ford power. The Merkur has the Sierra IRS and was imported for a few years but is somewhat rare. I think the Volvo is more common and cheaper. I have looked at the R200(8"ring gear) in Nissan 280z(Mcphearson Strut)and 280zx(Trailing Arm)also. More expensive but, with no upper control arms you have more room for dual exhaust.
JN Jim

Jim,

Are you looking at the R200S or R200L diffs? I'd be interested in what you're finding out about the LSD's available for those two options.

Also, whay CV axles vs. universals? What do they buy you for the extra cost (at least with the Nissan approach)?

Rob
x Ficalora

Rob, I don't know the S or L designation.The HybridZ message board has a wealth of information on the Nissan R200 diff and making coilovers on the factory 280z struts. The CV axle is stronger and allows more angularity. The clutch type Limited Slip is about $600 new. There is an improved Phantom Grip type posi with Kevlar washers for $250. The 280zx has tripod CV's while the 300zx Turbo has the ball bearing Porsche type(much stronger).The Strut type 280Z suspension is supposedly better than the 280ZX trailing arm type.The best find would be 87-89 300zx Turbo(finned cover R200,3.70,clutch posi,strong axles.Then find 280z mustache bar(crossmember)and control arms,struts,brackets,etc. I have pictures,diagrams,etc.
JN Jim

Jim, any progress on this thought?

Rob
x Ficalora

I noticed quite a few Nissan 240SX R200 and BMW rear members on EBay. Does anyone know the strength of the BMW unit. The newer 240SX has the Ford 5 lug pattern, the older; the MGB 4 lug. Plus the E brake pulls in like the MGB.
JN Jim

Jim,

I've been talking with a guy near me who has a Nissan based IRS under his GT. Shoot me your email & I'll be happy to send you some pics & info I've gathered.

Rob
x Ficalora

This thread was discussed between 27/07/2006 and 17/08/2006

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