Which O/D

[DavejBaxter]

I have 1500 dolomite engine, driving a 3 rail (Herald 1360) gearbox, and final drive. I am thinking of replacing the box with O/D unit. (Ex Spitfire?)
Q1.....which is the better box? 3 rail or single rail?
Q2.....which is the better O/D, Jtype or Dtype ?
and why?

[Clive]

I have a single rail dolly/spit box in my herald. The single rail is the "matching" unit and will bolt up with a 1500 flywheel and clutch, or if you are using a herald flywheel/clutch you would need a dolly 1300 clutch plate.
Some people prefer the 3 rail box, a nicer change, but little in it really.
If you use the 3 rail you can use the prop from a vitesse non od car as it is the correct length, if the single rail box it will be an inch too long. Also with the 3 rail you can get smalloutput flanges for the od, but the single rail only larger flanges, but thats a miner one.
I would see what good turns up!
Oh, j type a bit stnger and easier to wire. But generally good enough for a 6cylinder so a 1500 will not really bother it.

Clive

[DavejBaxter]

THanks Clive,  My gear change is already poor on the 3 rail, because Ive extended it back about 6 inches. Im the only one who can find reverse!!  Will have to extend a single rail as well I assume.  Did not realise that there different flanges for output, will watch out for that one.  I am watching a couple of boxes on Ebay at the moment, they fetch good money !!   Will see what I find.  No rush.
Dave

[Clive]

I would be VERY careful of ebay stuff. I get the impression much of the gearbox stuff is sold as unknown, which really means shagged. Better off buying from somebody who is recommended etc, especially as a recon box and overdrive would take the final pice over buying a recon setup from a proper supplier. Conversions are rarely cheap!
The flanges correspond with the early type (5/16 bolts) and the later types (3/8). J are all the later type, D either and the flanges are swappable or re-drillable. Or swap flanges on the prop.
Clive