Rear end swap to BMW?

[djw113uk]

With the Green PI diff wining, and the motorway miles I cover, plus the fact I have two BMW E34 530's going "spare" I wondered if anyone has tried installing a BMW rear into a MK11 saloon?

Aparantly the e28, older 5 or 3 series is the Monarch kit, but... surely somone has tried it? I dont mind being stuck with BMW wheels. I should (or could) end up with robust, taller ratio diff, CV jointed driveshafts, and rear disk brakes. All I need to do is make it fit.

Any ideas?

[wrighty]

Idea I want one

[ken]

HI if you have a spare rear end im up for having a go. Need a 3:07.1 or higher diff . know someone can make the prop shaft and redrill the hubs for the triumph stud patern for the wheels. will be at the nationals pop round for a chat

regards ken

[djw113uk]

I got the 2nd BMW as I didnt want to break up the one I had been using everyday. As yet it is still a complete car, but has become somewhat of a greenhouse at Mums! (they are both 1989 M30 engined (straight six), NOT the later V8)

It only owes me £85quid, and will weigh in for £40, so if you want to try and make it fit, and repeat the procedure on mine I will send it round! (Perhaps stick it in a trailer to the national for general consensus gathering?)

I am unsure of the ratio on the 530, as I cannot find it in any manual. But, the BMW was usually doing about 3000rpm at 80-85 - ish, so not that much better... but I guess other ratios are available?

[ken]

Hi I think theres a tag on the back cover with the ratio on .If you bring it to the nationals we can take some measurement and see whats to be modified to fit looking at the stag yesterday the rear mite be the hard work. It dosent matter if the engine was a 6 or 8

regards ken

[Alec]

Hello DJW,

I do not feel that there are enough advantages to warrant all the hassle, and there will be .
The rear subframe assembly is a tight fit in the body and I would bet the BMW unit will foul?

The Triumph ratio is theoretically enough for 150mph (assuming O\D), so it is hardly under geared. Rear disc brakes are not an advantage either. The only gain, which you haven't mentioned is that I would guess it has a limited slip differential.

It's not as though the Triumph unit is weak so I would take the easy option and get a re-conditioned or second hand unit?

Alec

[djw113uk]

The advantage to me is the reliability of the German units. My everyday use BM had about 180k on it when I got it. I have put a futher 75k on it, and the mechanics are near perfect, I just lprefer putting my money into the Triumph instead of a German barge. Most Triumph diffs wine, and the Driveshaft UJ's and spilnes are a weak link too. My BMW doesnt have a LSD, but is hopefully tougher. As most of the miles I do are motorway, any improvment in gear would also be good.

I have the BMW bits and they "should" fit. If I need another Triumph unit I have to find one, and it needs to be a good one.The BMW has to be worth a try?

[wrighty]

The standard box's in a triumph with overdrive could be up to 150 ....... Anyone hit that

[Alec]

Hello DJW,

fair enough but I don't agree that most Triumph differentials whine. I don't know the BMW's ratio but do be wary of overgearing as you will reduce tractability?

I did say 150 theoretically but i doubt if it would be possible with even the most radically modified Triumph engine, I would hazard a wild guess that 250 to 300 bhp would be needed to get that speed except when driving off a cliff?

Alec

[Allen Walker]

I did say 150 theoretically but i doubt if it would be possible with even the most radically modified Triumph engine, I would hazard a wild guess that 250 to 300 bhp would be needed to get that speed except when driving off a cliff?

Aerodynamics will always be the major problem I'd have thought, especially on a Mark 2. You'd have to deseam/de-gutter, blank off the grille, remove wing mirrors and bumpers, etc, etc. The Mark 1 is possibly a bit easier with its cleaner shape, especially if you retained the original rear track.
I think Ken's is more than 300bhp? And he managed 138 mph on a track. Very good going but I would imagine very hard/expensive to get much more.