Diff options and costs???

[YRRunner]

Ok, admittedly I'm thick and completely baffled by the diff options available for my Sagaris, not even sure what the standard (if there was such a thing) diff ratio is that I have fitted to mine. Could someone please enlighten me as to the pro's & con's of each 3.46, 3.7 and 3.91 options, and what I can expect to pay for a change-out? Mine is an early car, 2005. Original plate was GX05 ENV. Thanks in advance guys.

[RM75]

Can't help on the costs, but this spreadsheet can be downloaded and will give you an idea of how the different ratios will affect road speed etc...

http://www.varleyhyd.com/images/sag/gearspeeds.v2....

It's very good and has presets for all the usual TVR gearbox & diff combinations

Edited by RM75 on Thursday 5th November 11:33

[Targarama]

I have the 3.91 and it cost around £1200 fitted. I was told that the 3,91 need an extra part over the 3.73 option, adding a little bit to the price.

It is the most worthwhile mod I can think of for recent model TVRs running Speed Six engines.

[Don1]

You will also need the close ration box for the 3.7 or 3.91 diffs - otherwise other (expensive) parts of the car won't last long...

[L33]

My Sag came out the factory with the "wrong" diff fitted (Don't know what this means though).

I have an invoice when my Sag was 15 months and 11k miles old for part number R0662 with the description Sag Hydrotrak Diff 37

Any idea which ratio diff I have fitted please guys?

I also have the close ratio box - is this a good set-up?

Edited by L33 on Wednesday 4th November 20:19

[Targarama]

Don1 said:

You will also need the close ration box for the 3.7 or 3.91 diffs - otherwise other (expensive) parts of the car won't last long...

Eh? Why? Someone has been feeding you tosh.

The close ratio box has different ratios for 1st, 2nd and 3rd. Same for 4th and 5th (I used to think it was the first 2 gears only, but apparently its 3).

[Don1]

'twas something on here...

[Pixi]

I had the 3.46 diff. I have a standard box. I upgraded to a 3.91 diff, and kept the standard box. It is fantastic now - every gear-change goes into the engines sweetspot - before they felt a little mismatched. Reliability has been perfect.

Cost: GBP 1,048 including VAT - I got a good price as I had some other work done at the same time - expect to pay a little more.

There is a lot of stuff spoken on this topic - my suggestion would be don't over analyse it, don't heed every opinion unless they've had the work done themselves.

[Targarama]

L33 said:

My Sag came out the factory with the "wrong" diff fitted (Don't know what this means though).

I have an invoice when my Sag was 15 months and 11k miles old for part number R0662 with the description Sag Hydrotrak Diff 37

Any idea which ratio diff I have fitted please guys?

I also have the close ratio box - is this a good set-up?

Edited by L33 on Wednesday 4th November 20:19

Only you know whether it is a good 'setup'. Do you like it? Well there you go then.

You'll need to get under the car and see if you can read the tag on the side (if it has one). I think they're all Hydrotak so that's nothing special. The 37 at the end hints to me that you may have the 3.73, but of course I actually know nothing, I'm just an Internet warrior with suggestions.

[L33]

Targarama said:

...but of course I actually know nothing, I'm just an Internet warrior with suggestions.

Arn't we all?

[YRRunner]

I was under the impression that all Sags came out of the factory with CR boxes.
Looking at the spreadsheet, I wonder why anyone would choose to move up to the higher ratio diffs. Is it me, or do they appear slower through the gears the higher you go up? Power delivery seems to smooth out, but is this really a good substitute to the apparent sheer aggressive response of the 3.46??? Am I missing something?

[TVR_owner]

YRRunner said:

I was under the impression that all Sags came out of the factory with CR boxes.
Looking at the spreadsheet, I wonder why anyone would choose to move up to the higher ratio diffs. Is it me, or do they appear slower through the gears the higher you go up? Power delivery seems to smooth out, but is this really a good substitute to the apparent sheer aggressive response of the 3.46??? Am I missing something?

All Sags came with standard gearbox unless you specified the cost option.

and..........Yes, you are missing something, but if you're happy with the erm...agressive response of the 3.46, then why bother.

[YRRunner]

Thanks John. As I'm not the original owner, and don't have the original invoice, is there anyway I can find out what options my car came out of the factory with? Cheers.

[TVR_owner]

YRRunner said:

Thanks John. As I'm not the original owner, and don't have the original invoice, is there anyway I can find out what options my car came out of the factory with? Cheers.

You could try and contact the supplying dealer (info in service book) and see if they have a copy of the build sheet - its worth a shot I guess.

[hairyaardvark]

My Sag was originally the 'standard' box and the 3.46 diff.
I recently had this upgraded at RG, electing for a close ratio box, and Quaife LSD with 3.91. Also had their lighter Simplex timing chain kit fitted at the same time.

I've yet to compare it with previous form on the track (the Quaife LSD in particular is supposed to aid in laying down the power out of tight corners), but on the road the car 'feels' a lot quicker through all the gears. Response is still linear and smooth, but the car revs a lot more freely right to the top end, and as I've said above - subjectively at least - it feels massively faster than before. Third gear in particular seems to last forever.

The CR box seems to force an adjustment in driving style .... most noticeably 1st gear is a lot longer than before, and the car doesn't like me to snatch 2nd gear as early as I used to (it'll bog down slightly if you change into 2nd too early).

All in all a very worthwhile upgrade. Not cheap though.

cheers
DR

[willtvr]

YRRunner said:

I was under the impression that all Sags came out of the factory with CR boxes.
Looking at the spreadsheet, I wonder why anyone would choose to move up to the higher ratio diffs. Is it me, or do they appear slower through the gears the higher you go up? Power delivery seems to smooth out, but is this really a good substitute to the apparent sheer aggressive response of the 3.46??? Am I missing something?

Haven't heard of anybody changing to a higher ratio on here. Any post I have seen refers to fitting a lower ratio to improve acceleration.

[Targarama]

willtvr said:

YRRunner said:

I was under the impression that all Sags came out of the factory with CR boxes.
Looking at the spreadsheet, I wonder why anyone would choose to move up to the higher ratio diffs. Is it me, or do they appear slower through the gears the higher you go up? Power delivery seems to smooth out, but is this really a good substitute to the apparent sheer aggressive response of the 3.46??? Am I missing something?

Haven't heard of anybody changing to a higher ratio on here. Any post I have seen refers to fitting a lower ratio to improve acceleration.

Depends how you interpret it I guess. I see 3.91 as a higher ratio than the other two. It means my car now has a theoretical top speed of 176mph vs 195mph with the standard diff ratio. A speed it can actually attain instead of fantasy gearing.

Edited by Targarama on Friday 6th November 14:48

[VARLEYHYD]

Targarama said:

Depends how you interpret it I guess. I see 3.91 as a higher ratio than the other two. It means my car now has a theoretical top speed of 176mph vs 195mph with the standard diff ratio. A speed it can actually attain instead of fantasy gearing.

Hi Targ,

Not read the full thread, but do you have standard box with 3.91:1?

May go 3.91 route, but not sure the CR box is right for my local circuit.


G

[Targarama]

VARLEYHYD said:

Targarama said:

Depends how you interpret it I guess. I see 3.91 as a higher ratio than the other two. It means my car now has a theoretical top speed of 176mph vs 195mph with the standard diff ratio. A speed it can actually attain instead of fantasy gearing.

Hi Targ,

Not read the full thread, but do you have standard box with 3.91:1?

May go 3.91 route, but not sure the CR box is right for my local circuit.


G

Yes I have the standard gearbox. I've not changed it as I am perfectly happy with the combination, which IMO works very well. Maybe a CR box would be even better, I don't really care and won't contemplate changing the gearbox ratios unless the current one packs up.

[crimbo]

We have a CR box and a 3.9 quaife, I think we have a receipt somewhere from the previous owner for £1000-£1500 for the dif, I have not been in a TVR with a different set up so I cannot comment on how it compares but I can say it pulls well in 3rd out of tight corners and when on the motorway at 70mph or so it is not revving to high so that its annoying. The gears seem nicely distanced as well but when pulling off 1st does seem a very tall gear but we are used to cars that do about 30mph in 1st, I can’t imagine how it would feel with a 3.4 diff and CR box, from my understanding the 1st gear would be longer still.