Single rail overdrive

[Maidstonerob]

Any suggestions on where best to get a recon overdrive unit from should I decide to bite the bullet and cough up for one?

[wiggybum]

For a 1500 or 1850?

[Maidstonerob]

1850 but i thought the units were the same???

[wiggybum]

Similar, but not the same. 1850 has the GT6/Vitesse close ratio gears, different input shaft (different clutch) and different bell housing. Reverse is in the same place on the gearknob though. You won't need a shorter propshaft but a different speedo cable.

I only ask because the 1500 ones are worth a lot more, even when knackered. This is because they fit Triumph Spitfires and some of those owners will pay £££ for the privilege. Overdrive was a really expensive optional extra when the cars were new. I'm sure I read somewhere that they cost £500 back in the 70's hence most 1500 Dolomites and Spitfires didn't have it. Shame, as it really transforms the car.

So, the 1850 one only fits 1850s (and maybe GT6s/Vitesses) which means they are (should be) cheaper. Best bet is to keep looking on the sales pages on this forum and put a wanted add in for a used one which you can exchange with any of the usual firms. Make sure you also get the angled speedo drive as these are normally missing.

[Maidstonerob]

I have one which is suspect just looking at options for repair or replace. Hoping you can get a recon one with some confidence that new replacement parts are of the right quality. Dont want to fork out for one and it be in reality no better than a second hand gamble but having had the probs with the drive train as it is I dont want to fit a dud. Time is drifting by and really want to make some progress toward getting her finished and back on the road

[wiggybum]

Well, in general the overdrive is well over engineered for an 1850 so will probably only need the filter cleaning and putting onto a recon box.

I got mine from John Kipping in the 1990s which is still going strong today (shame the same can't be said about John!). I've heard Mike Papworth in Coventry is good. I'm sure one of the guys from your neck of the woods will know where to go.

I understand that very good, British made gearbox parts are still made in Coventry :

http://www.shop4autoparts.net/Triumph/Gearbox

[Henk]

These are the two main suppliers I guess:
http://www.odspares.com/
http://www.overdrive-repairs.co.uk/

I fitted one to my three-rail-box, but I think the project is nearly the same. The gearbox has to be rebuilt with an other type main shaft. So it's not simply bolt on and go. You'll lose the small tail at the back of the box, instead you'll need an adaptor ring to bolt the OD on.

[wiggybum]

I forgot to mention you'll also need the o/d gearbox cross member and mount. There should be loads of those about as they are common for all Dolomites with o/d. the holes for it are already in the chassis rails.

[Maidstonerob]

Sorry just clarify

Mine has overdrive but after having the box reconditioned the overdrive unit appears to have become faulty. There was a lot of swarf in the gearbox however investigations have shown the box not to be the source. Therefore naturally the heavy swarf contamination is suspected to be from damage to the overdrive unit.

I am just unsure wether to have my od unit repaired or replaced with second hand or if i decided to go the whole hog and buy a recon overdrive where was best

[wiggybum]

Overdrive Spares in Rugby are excellent.

[Toledo Man]

I think you're best just biting the bullet and getting the OD reconditioned...

[xvivalve]

Rob, when Susie owned the car the overdrive failed, the cone clutches went so that when engaged it felt as if the clutch on the car was slipping. She replaced the overdrive unit with a known good one with the gearbox in situ; she did this herself, albeit with me watching and was a moment of great pride for her, and was again when she sold the faulty unit at the Triumph Show that year for more than the job had cost her! (with the faults declared, I hasten to add!)

Whether or not the faults then caused swarf or not, I cannot say, but she didn't change the gearbox oil at that juncture, just topped it up.

A little history may help your decision...? What faults is the o/d exhibiting now?

Oh, and to clarify, the 'J' type overdrive units themselves only really differ in respect to the mounts for the remote box; from memory, your's needs the two bolt holes to support the gear stick, whereas one from an earlier car won't have those holes, or for that matter the bosses on the casting.

[Jon Tilson]

Just so you all know and dont duplicate advice...

This overdrive unit came to me and was added to an 1850 single rail box that I built up with all new bits
a while ago. I have stripped the box again and all is well. It seems as Rob has said that the o-d unit is therefore
at fault.

We will see when I get round to stripping the o-d. Sadly its all a bit life swamped at present. If this one has a new cone clutch I'm more inclined to strip and redo the bearings if Rob has the patience....

Rob's original box had the typical shot sycnhro cones and a badly worn layshaft, clearly the source of the original noises.

Jonners

[xvivalve]

It didn't have 'new' cone clutches, it was just known good having come from a car of known history.

[Maidstonerob]

Thank you everyone for your input and suggestions.

Jons efforts thus far have been very much appreciated

I just want to get everything back in the car without the worry of having to take it all back out again. This is why I'm thinking of going for a newly reconned unit rather than chancing a second hand replacement. I was just concerned as to some views on the quality of replacement parts being sometimes suspect these days, as I dont want to fork out for a recon to find it would be little better than a second hand unit and have to be stripped back out all over again.

If im going to spend I want to spend wisely is all