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I currently have a Triumph Dolomite 1500 engine with the standard Herald 1200 gearbox in my Herald with worn big ends, generally in need of a rebuild. So, I've located a possible replacement, in the form of an MG Midget 1500. Now I know in theory these are the same as a Spitfire 1500 engine, but in practice are there any differences? Engine mount placement? Also how does the MG gearbox (I believe they were based on the Marina gearbox?) compare in terms of ratios/strength of a Herald and Spitfire gearbox? Is the gear stick going to be in the wrong place? Cheers for your help  |
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Last Edit: Jun 7, 2012 13:58:12 GMT by yantorsen
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ChasR
RR Helper
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Posts: 10,309
Club RR Member Number: 170
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FWIW the gearboxes in Midgets are not the strongest of items and IMO not that practical for everyday use (unless you stick to town work) they are IMO geared a little too short for a Midget (it never came with the option for an overdrive in 1500 guise). To be fair when working right they are a sweet and slick little 'box (most I drove (including my one) had knackered syncros) . Here is a question for the Herald owners, does the Spitfire overdrive 'box fit a Herald? . In theory the mounts etc. should be the same or transferrable between the two engines. To make life easier I would personally stick with the 'box you have. |
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Last Edit: Jun 7, 2012 15:33:37 GMT by ChasR
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Okay.
The only reason I really asked was because I currently have a Herald box, not a Spitfire one, thought the midget one might be higher geared. Also the replacement engine has the Midget box already attached so saves having to swap it.
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ChasR
RR Helper
motivation
Posts: 10,309
Club RR Member Number: 170
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Fair enough. Sorry if I came across a little brash! I said about the high gearing since besides the later Midget 1500s (I think they changed the diff ratios) mine did around 3,000rpm at 55MPH in 4th. If the gearbox fits you *may* need another prop, hence why I figured it would be easier to stick with the Herald 'box . |
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I suspect that all the boxes are 1:1 top - most old 4-speeders are - with the gearing changes in the diff (or overdrive if fitted). Oh, and a 'rumph 1500 with worn big ends? Who ever heard of such a thing?  |
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PHUQ
Part of things
Posts: 864
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Marina, Spitfire and Dolomite boxes are essentially the same (different ratios, no overdrive option on a Marina, different input shaft lengths) as far as I'm aware, all with a 1:1 4th gear. Assume the Herald one probably is too, can't say for the Midget.
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Any 1500 Triumph engine should have thrust washers replaced automatically before engine fitment. Even if no noticable play unless a recon unit or known history then why risk the chance of them falling out of the locating lugs or whatever. For the cost of a sump gasket at very least check them first.
Paul H
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And the big ends and probably the mains too.....
I think the 1500 Midget box is the same as non-OD Dolly 1500 / Spit 1500 to all intents and purposes. It will have a different size output flange compared to a Herald one so you will need to swap the UJ as a minimum. It may also be a bit longer than the Herald one meaning a shorter propshaft is needed - not sure as I've only messed with the overdrive versions.
Whichever, they all have 1:1 4th gear. This is not great in a 1500 Herald with the standard 4.11 diff. First gear pretty much useless and the engine is bawling it's head off by 60mph. You really need overdrive or the 3.63 diff from a 1500 Spitfire - preferably both - then you have a great car, nippy and relaxed cruising.
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Okay cheers all.
So what is the verdict on gearbox? If I were to change the diff etc. how easy is that to do? Is it going to involve taking half the back of the car off?
Can't help but think if I'm going to the effort of changing all that may as well just go all out and stick a k series in it?
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Last Edit: Jun 8, 2012 9:19:48 GMT by yantorsen
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Okay cheers all. So what is the verdict on gearbox? If I were to change the diff etc. how easy is that to do? Is it going to involve taking half the back of the car off? Can't help but think if I'm going to the effort of changing all that may as well just go all out and stick a k series in it? The general feeling I got from the above is that it's probably not worth the bother when it won't even do anything to up your gearing. I'd be looking out for an OD box and/or a taller diff for it. Don't underestimate the amount of work that would be involved in a totally alien engine swap EDIT: I used to have a 13/60 with its standard engine but a J type overdrive from a spitfire and it made it a FAR nicer place to be when driving any distance. I never checked what diff was in it. |
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Last Edit: Jun 8, 2012 11:58:06 GMT by ben711200
...proper medallion man chest wig motoring. |
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Okay cool makes sense.
Yeah a totally alien engine swap does seem pretty daunting, as if a normal engine swap wasn't already ha.
However all this might be academic, I've found someone who's willing to rebuild the engine for £400, so may just do that.
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K series engine swap will not be especially easy.
MX5 engine complete with gearbox seems to be quite straightforward. Seth of this forum has done this to great effect and even has it running on 2 x SUs, which is a nice touch.
Another one which seems attractive but may be more involved is to use a Zetec SE from a Focus or Fiesta with a Type 9 gearbox (special bellhousing needed I think).
Nothing wrong with the 1500 conversion really, but it really does need the higher gearing to make use of the extra torque and keep the revs down. Unlike the 1200 and 1300 engines, the 1500 does not like to rev and makes it's displeasure known by shouting loudly and wearing out rapidly.
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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