Overdrive or 5 speed box?

[johnny250]

As I'll be removing the gearbox for attention, (other thread) I'm considering fitting overdrive. I've always been happy with the ratios I have with the diff fitted, but now the engine is performing even better, I can sometimes reach 5500rpm in top, which is where the rev limiter is set.

What parts do I need for an effortless change?

The alternative is a 5 speed box conversion.....anyone any experience in UK (I know that one is available USA)

 

thanks

john

[had17462]

John i looked into this a few years ago and the cheapest i could find was a company in essex ,i think it was benfleet, they used a ford box and they had a demo tr6 as well so u could test drive it etc,price then 1450 supply ,but i went with overdrive as the guys on here said why have 5 when u can have 7!

nick.

[dykins]

I think I'm right in saying that both Moss and TR Bitz offer a 5 speed conversion (the latter is from a Toyota I think). I seem to recall they are priced at around £2,300 excluding fitting.

 

I think that a reconditioned overdrive is the best option, and as it is closer to originality would help when it/if comes to selling the TR.

 

Regards

 

Peter

[johnny250]

thanks chaps,

after consideration the overdrive option is the preferred solution.... I'm sure it's been discussed before, but what parts do I need to acquire to make the change? (propshaft/mountings/wiring etc) I would be prepared to get a complete gearbox/overdrive assembly, rather than adding to the box I have, but wouldn't want to lose the current TR250 ratios.

 

john

[stuart]

thanks chaps,

after consideration the overdrive option is the preferred solution.... I'm sure it's been discussed before, but what parts do I need to acquire to make the change? (propshaft/mountings/wiring etc) I would be prepared to get a complete gearbox/overdrive assembly, rather than adding to the box I have, but wouldn't want to lose the current TR250 ratios.

 

john

 

You only need wiring and relay as prop and mounting (At least for "A" type) is the same. If you want to keep the same ratios then get a mainshaft/adaptor plate/overdrive unit and have it added to your present box. (After sorting the 3rd gear prob )

Stuart.

[johnny250]

thanks Stuart,

what are the pro's/cons for the A or J types? I'm looking for reliability over originality as the car isn't standard anyway.

 

john

[stuart]

thanks Stuart,

what are the pro's/cons for the A or J types? I'm looking for reliability over originality as the car isn't standard anyway.

 

john

 

A Type available for 2nd 3rd and 4th, snappy engagement and correct for car. J type only 3rd and 4th recommended but slower engagement and cheaper to find but different mounting requiring chassis mods or special adaptor mounting plate (Also usually requiring modifications for good fitting). Both reliable if rebuilt correctly. (Personal preference A type)

Stuart.

[Guest ntc]

(Personal preference A type)

 

All day long

[TR 2100]

A Type available for 2nd 3rd and 4th, snappy engagement and correct for car.

J type only 3rd and 4th recommended but slower engagement and cheaper to find

but different mounting requiring chassis mods or special adaptor mounting plate

(Also usually requiring modifications for good fitting).

Both reliable if rebuilt correctly. (Personal preference A type)

Stuart.

 

Remember also that the correct overdrive, and in particular the correct

A type overdrive, will add more value to the car. They don't come cheap,

though, and then there's the cost of a rebuild.

That depends partly on the condition of the box you are rebuilding, so

exact cost cannot be guaranteed.

 

Not suggesting that you are intending to sell, ever, but there's also

the satisfaction of knowing that the overdrive is as it should be, but

it's logical to take into account the increased value of the car as part

of the justification for the work.

 

That being said, the joy of having overdrive (through the gears, not just

4th) is justification enough.

 

AlanR

[johnny250]

OK that's settled then..I need an A type overdrive with/without gearbox...anyone?

 

What cars are they fitted to? i.e will an Etype or Volvo fit!

 

john

[Guest ntc]

OK that's settled then..I need an A type overdrive with/without gearbox...anyone?

 

What cars are they fitted to? i.e will an Etype or Volvo fit!

 

john

 

 

Maybe Marko can help you out? but remember a good one does not come cheap. and they should be rebuilt together

Edited November 9, 2010 by ntc

[david ferry]

Personally, I'd talk to ORS in Sheffield about this.

 

I'm sure that they will have the correct unit that they can rebuild and then fit to your gearbox, which they can rebuild too, along with being able to supply all the parts that they will need to complete this job successfully.

 

I've got two of their overdrive gearboxes in cars that need to be to an original spec and I've also got a Toyota 5-speed gearbox in a car that doesn't need to be to original FIA type spec.

 

The Toyota gearbox is very good but it does present a couple of other issues that need to be resolved in fitting it (they have been resolved).

 

I know people talk about the joy of an overdrive gearbox. However, they are heavier than a non-overdrive gearbox and whilst a oproperly rebuilt one should last a reasonable length of time, I fully expect that a Toyota 5-speed gearbox from a Supra will far outlast the TR overdrive box and should it wear out, it will be far easier and cheaper to repair.

 

David

[stuart]

OK that's settled then..I need an A type overdrive with/without gearbox...anyone?

 

What cars are they fitted to? i.e will an Etype or Volvo fit!

 

john

 

Etype doesnt have one. Earlier Jaguar boxes do have them and they are strong units but command good money and still need tail housing and speedo drive changes. Volvo ones will fit but later units are J type again.

Stuart.

[Tom Fremont]

Earlier Jaguar boxes do have them and they are strong units

 

That should tell us something as the MKIIs had 3.4l ( and 3.8l? ) engines with half again as much HP and even more torque relative to a CP TR6. These were strong units indeed, and likely would have lasted even longer in TRs if they didn't share oil with the gearbox ( which failure will often cause collateral damage to the O/D ).

 

I guess I've done ~ 120,000 miles with A-type O/D boxes and never had a problem; the boxes always came out due to layshaft failures. I do keep a spare 'box as I hate to be without my driver for longer than a swap requires

[stuart]

That should tell us something as the MKIIs had 3.4l ( and 3.8l? ) engines with half again as much HP and even more torque relative to a CP TR6. These were strong units indeed, and likely would have lasted even longer in TRs if they didn't share oil with the gearbox ( which failure will often cause collateral damage to the O/D ).

 

I guess I've done ~ 120,000 miles with A-type O/D boxes and never had a problem; the boxes always came out due to layshaft failures. I do keep a spare 'box as I hate to be without my driver for longer than a swap requires

 

You do have to remember in the Jag they were only O/D on top as 210 plus horses and huge amounts of torque will make a mess in second

Stuart.

[Guest ntc]

That should tell us something as the MKIIs had 3.4l ( and 3.8l? ) engines with half again as much HP and even more torque relative to a CP TR6. These were strong units indeed, and likely would have lasted even longer in TRs if they didn't share oil with the gearbox ( which failure will often cause collateral damage to the O/D ).

 

I guess I've done ~ 120,000 miles with A-type O/D boxes and never had a problem; the boxes always came out due to layshaft failures. I do keep a spare 'box as I hate to be without my driver for longer than a swap requires

 

 

As I said Ors are the best at overdrive's full stop. you should use a good gearbox man that brings the two together ie: Roy Talbot,Peter Cox etc .Cleanliness is paramount in this as in engine building if you want it to last

[Tom Fremont]

You do have to remember in the Jag they were only O/D on top as 210 plus horses and huge amounts of torque will make a mess in second

Stuart.

 

 

Point taken!

[rpurchon]

OK that's settled then..I need an A type overdrive with/without gearbox...anyone?

 

What cars are they fitted to? i.e will an Etype or Volvo fit!

 

john

 

what you need is a sprint or any later gearbox saloon stag 2.5 cr tr6 which will have all steel bushes inside. much stronger.

if you can get hold of A type gearbox it will have bronze bushes in the gearbox.

[if your having problems with yours it will probably be bronze top hat bush thats cracked]

simply put the later gearbox parts on the a type mainshaft.

best bet is to buy a sprint gbox change the input shaft for your tr one and fit.youve then got odrive.

then trawl ebay for six months looking for A type odrive gboxs.not just triumphs.look for rovers etc

they are basicly the same inside.you should be able to get a few for £200 if your patient then sort your a type out at leisure.

richard

ps i have sent for a megajolt, and getting bits and pieces to convert.then by by condensor.

[pfenlon]

John the A type is the one to get, I gave my gearbox (without O/D) to TR Bitz and they reconditioned it and supplied an overdrive unit from sheffield for about £950?

 

I have only done about 2500 miles but without a problem.

 

I once went for a J type and the mounting that had to be modified was a bloody mess, and for the money it isnt worth rebuilding them yourself really.

 

I have a 3.4 diff and the engine is really long legged at about 3000 rpm its doing around 80 mph.

 

I did fit a PI system though, carbs would be ok too I think, but maybe Stuart would know better.

Edited November 10, 2010 by pfenlon

[marko]

Johnny 250 - I've had a TR250 with a 5 speed Toyota conversion and it was brilliant (The car resides near Peterborough so not a million miles away from you). If I was running a TR for myself then this would be the route I would go, I can't stress how good they are with 5 speed!

 

If you want to beef up the original A Type then consider a Stag gearbox with beefed up internals.....TR4Tony is probably the person to talk to here as I believe he runs them?

[johnny250]

Thanks chaps,

I've taken the plunge with an unknown quantity box and Atype O/D (£££ )..... I'm having a go at the overhaul, so look forward to lots more Q&A

 

john

[pfenlon]

All power to your elbow there are fewer of us that will have a go themselves.

 

keep us posted, the A is a good un though.

Edited November 15, 2010 by pfenlon

[jerrytr5]

A couple of points that I discovered when I rebuilt my box:

There are at least two different types of laygear & they will not mesh due to different angles (of the gear). Gearbox rebuilding virgins (like me) can't tell the difference by sight (believe it's 1 degree) until we find it doesn't all fit together on final assembly. Be warned.

I was advised to use the steel top hat bearing, however the steel one doesn't have a hole for the oil supply to/from the shaft so I was not inclined to use it on the basis that the old one was bronze and therefore self-lubricating and still needed a hole, so what chance of the steel one seizing - you might need to seek further advice here. And no, you can't drill it - I tried and it's bullet-proof.

You will probably find reference to using a Stag layshaft thrust washer - when I investigated these were NLS.

I presume you are aware of the layshaft mods to double up the bearing?

Good Luck. Mines still running

Jerry

[johnny250]

Thanks chaps,

I'm still accumulating necessary info and tools etc before lifting the lids.... I'll be using the step by step guides from Buckeye Triumphs.

http://www.buckeyetriumphs.org/technical/technical.htm anyone else used their info?

I did build my present box and enjoyed doing that....

What's the layshaft mod Jerry?

 

john

Edited November 16, 2010 by johnny250

[jerrytr5]

The layshaft always runs the needle rollers (in the rear end I think), so you need to bore out one end so that there is space for two sets of new bearings (ie: halving the loading). At the front there is a mod to replace the thrust with one from a Stag. However I understand that this requires machining to the casing and also they (may) no longer exist.

Other than that, it's a piece of piss

Jerry