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Hi guys. I hope you are all keeping well. A quick question for you about my diff.......Ive had my TR6 for about 7 years, I think, I have never driven it and it is undergoing a complete never ending rebuild. I have got to the diff part and am not sure what to do. All of the seals are weeping and as I haven't driven it I am unsure if there are any clonks or whines. Having looked at the brown book it seems that changing the seals is a job I could do, or should I have it checked and refurbed professionally?

Thank you, in advance, for your collective brain power.

Jez

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Hi Jez,

The diff is one of the more awkward things to sort out.  The seals are do'able but you may need an extractor for the output seals

Why not take it to Hardy Engineering in Leatherhead and then you can get on with something you are more comfy with.

 

Roger

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4 hours ago, RogerH said:

Hi Jez,

The diff is one of the more awkward things to sort out.  The seals are do'able but you may need an extractor for the output seals

Why not take it to Hardy Engineering in Leatherhead and then you can get on with something you are more comfy with.

 

Roger

+1, there's more to this job than just leaving the diff mounted, sliding the shafts out and then  replacing the seals.

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Assuming you are above stuffing sawdust in the oil to quieten the whine and swelling the seals with additive to cure leaks, its a specialist job.

Peter

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Jez - always worth checking the diff ratio before doing anything else. As standard a UK TR6 would have had a 3.45 ratio but who knows what happened during it's life.

Was helping another member tidy up his UK TR6 and it had leaking seals etc - expecting it to be a 3.45, it turned out it was a 4.1! Superb acceleration but poor cruising ability and even worse fuel economy.

Export TR6's to the States had 3.7 ratios, hence why it's important to check so you don't renovate a diff which ultimately doesn't suit your requirements. In addition to Hardy Engineering who have a good reputation, you could also try Pete Cox Sports Cars ( https://petecoxsportscars.co.uk/spares-shop/ols/products/tr6-3451-differential ) who always rebuilt my diffs, and I believe have rebuilt units on the shelf to exchange.

If you don't know how to check the ratio in the car, jack up one rear wheel, making sure the other can't turn, with neutral selected, and chalk mark the wheel and the propshaft - turn the wheel two full revolutions and count how many times the prop goes around - the ratios will equate as near as dammit to four, three and three quarter or three and a half revolutions to give you your ratio.

Hope this helps 

Cheers Rich

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Thank you for the advice guys. I’ve decided to take it to Hardy Engineering. 

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As for economy I disagree you use more fuel getting up to speed indeed a good friend of mine in a USA spec car on stombergs followed a group of us to Le man and kept pace and used no more fuel than us and there was no overdrive fitted go figure 

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15 hours ago, ntc said:

As for economy I disagree you use more fuel getting up to speed indeed a good friend of mine in a USA spec car on stombergs followed a group of us to Le man and kept pace and used no more fuel than us and there was no overdrive fitted go figure 

Maybe the carburettor engine is more economical than the PI? Hard to believe that lower gearing for acceleration saves any significant amount of fuel, whilst higher gearing at steady speeds certainly does. All modern cars have high (overdrive) top gears.

Mike.

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16 hours ago, ntc said:

As for economy I disagree you use more fuel getting up to speed indeed a good friend of mine in a USA spec car on stombergs followed a group of us to Le man and kept pace and used no more fuel than us and there was no overdrive fitted go figure 

Interesting, but hardly a comparison.

Tyre size, style of driving, weight of driver and payload etc.

John.

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16 minutes ago, John Morrison said:

Interesting, but hardly a comparison.

Tyre size, style of driving, weight of driver and payload etc.

John.

Quite so John,

plus - tyre pressure, tyre make and model, Boot rack etc, headlights, heater fan, radio etc etc binding brakes.

Ad infinitiumnium,

 

Roger

Edited by RogerH
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The PI is an appalling design with respect to economy. It has to be run rich conitnually at cruise to avoid rattling the pistons when wotting the throttle. The rich cruise mixture made the vac advance redundant. Normally the cruise mxiture would be leaned and the spark advanced ( eg carb vac take-off disy capsule). Carbed 6s should be able to easily beat PI mpg, providing the comp rat is not left at USA specs. Tuning for mpg is a fascinating topic, that has yet to rise to the fore........

Peter

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1 hour ago, Peter Cobbold said:

The PI is an appalling design with respect to economy. It has to be run rich conitnually at cruise to avoid rattling the pistons when wotting the throttle. The rich cruise mixture made the vac advance redundant. Normally the cruise mxiture would be leaned and the spark advanced ( eg carb vac take-off disy capsule). Carbed 6s should be able to easily beat PI mpg, providing the comp rat is not left at USA specs. Tuning for mpg is a fascinating topic, that has yet to rise to the fore........

Peter

Agree Peter, and as you know I used an AFR to try and improve the PI economy. It is possible to do quite a lot better than the stock settings but you are always fighting lean pinking at snap WOT. Now, my supercharger setup... thats surprisingly frugal, unless I push it!

Tim

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Interestingly the Stag was generally supplied with a 3.7 diff.. many, like me, have swapped it for a 3.4..

Tim

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