Manta B2 GTE - Competition Diff set up?

[Kit_400R]

I'm considering a highly tuned 2.7 turbo volvo engine conversion, what is the max tolerance of the GTE rear diff and what choices do I have for upgrades since I should be pushing 400-500 bhp and 450-550 ft/lbs?

Do you think I could just buy quaife ATB helical LSD differential, or am I in danger on snapping something running this power?

[oppositelock]

The Opel rear axle will never handle that, not even close. The rear axle was the Achilles heel of the original 400 works rally cars. They had many DNF's due to rear axle failure and they were "only" putting out 240-275 bhp. Even the Volvo Dana 30 won't handle the kind of torque you're talking about, unless you're just puttering around on the street. If you're going to drive it hard, though, you'll need something like a 9 inch Ford or possibly a Toyota Pickup 8 inch, though I'm not sure that would hold up for long. The Quaife ATB definitely won't stand up to that.
My friend and I built a Volvo 240 rally car with a turbocharged 3 liter V6 putting out over 500 ft/lbs of torque to the rear wheels and it easily twisted the half shafts off the Dana 30 so we upgraded to a 9 inch Ford with 35 spline Moser axles. Some pics below.

[GTJIM]

Being close to the UK there should be a few necessary parts available close by.
For a brake upgrade see:

Manta Brakes and Braking systems, improvements, upgrades and modifications


For the rear axle; a narrowed Opel Commodore B GS/E unit, with LSD & disc brakes, apparently the same as on the Manta 400.
OR a modified SD1 Rover diff - you can retain the Opel style torque tube; the Rover Sailsbury diff is stronger and gears/LSD units much easier to find.
See here:
http://www.mantamagic.com/v8manta4.htm

Another option is a 'built' 10-bolt or 12-bolt GM/Chevy diff if you want to keep a 'stock' appearance - plenty of gear ratios and several types of LSD available at good prices.

[namba209]

Originally Posted by Kit_400R I'm considering a highly tuned 2.7 turbo volvo engine conversion, what is the max tolerance of the GTE rear diff and what choices do I have for upgrades since I should be pushing 400-500 bhp and 450-550 ft/lbs? Do you think I could just buy quaife ATB helical LSD differential, or am I in danger on snapping something running this power?

Actually, the weak link on the Opel drivetrain is where the driveshaft inside the torque tube goes in to the differential. RallyBob has stated numerous times he has a box of those shafts that have the splines worn away/stripped in stock configured cars. Best bet, for something that is pushing that much torque is a completly different drive train.

[baz]

the opel rear end is a dog will not live with much more than stock with heavy use so it needs every thing from the gear box back sorting
theres a thread knocking about of swopping in a BMW rear end , this would be good for you or i think with a little work a ford sierra cossy rear would go under it and live for a while but nothing from the rwd opel range will live long with 500 lb/ft of torques except maybe a lotus carlton rear end and they are as rare as rocky horse droppings much as a 9" ford rear is over here

[oppositelock]

Originally Posted by namba209 Actually, the weak link on the Opel drivetrain is where the driveshaft inside the torque tube goes in to the differential. RallyBob has stated numerous times he has a box of those shafts that have the splines worn away/stripped in stock configured cars. Best bet, for something that is pushing that much torque is a completly different drive train.

Also, as a note (or perhaps a hint) the works 400 rally cars did not use the torque tube but went with a full five link setup.

[lamchop77]

Know a guy who runs a 2.9 Volvo Evo in a class 3 Autograsser and he uses a quaife custom diff. Fitting the sierra rear end is probably the best route to go down. I have fitted a std set up with a locked diff under my Class 3 Kadett coupe. Took me about 2 days to sort it with a bit of preliminary work. Sierra back end is the same width,virtually, as the manta. I even fitted the sierra rear springs because the bottom swing arm spring mounts actually lined up with the kadett mounts, unbelieveable!!

Cossy / 4x4 rear ends are more expensive but they have had enormous amounts of power through them. I have seen a std locked 1600 sierra diff and driveshafts with 360 bhp run through them when i used to race superbangers on a tarmac oval, and that never gave up the ghost in 3-4 years. Plus the wheels on the axle were different rolling radii for the stagger that the cars ran so the drivetrain did put up with ALOT of grief.

Only other axle that i can think of for that type of power (other than the ford 9") is the Sellholm racing axle based on a Volvo set up. Its advertised as a cheaper, stronger replacement for the Atlas. Think a guy in Ireland is the UK supplier.

HTH

Chris

[Motor Mouth]

Chap in our club has had his GT to run a BMW 325i LSD rear end.

But if you want to keep it Opel i do have a Commodore GSE that i'm breaking. The GSE has an ZF LSD fitted, you can get a 5-link set up ala 400's and if you buy the front hubs off me too, you get a full 5 stud conversion.......proper 400 styley!!

[Manta Rallier]

I dumped my ong reply by mistake so here is the short one:
Any Opel axle being reliable with 400-500 HP? No way!!
Ford 9": easy to get, lots of parts, handles 600+hp with no problem; ready parts for 4 link brackets etc., can be bought in narrowed versions to match the flange-to-flange length you want.....

Sounds like a cool car; good luck there!
Mark B.