Diff ratio

[tuscanturner]

Having finally fitted the v8 into my taimar it has decided to find the weakest links going out to the tyres!
Hence the recovery truck at the pre 80s

I'm looking into upgrading the diff and axel components,Can anyone recommend a suitable diff ratio? The is used primarily for the road with a bit of track day action if it's not too loud.

[madsvlund]

Hi, you shall consider the total drivetrain ratio, gear ratio in highest gear, diff ratio and wheel diameter. Another topic is total ratio split (1'th gear ratio / high gear ratio)

For my M do I run with a broad torque engine (works from 1500 to 7000 rpm) I have a street gear box with a total ratio split of 423%, 5'th gear ratio is 1:1, rear wheel circumference is 1.997m, with a 3.15 final ratio do that equal 38kmh@1000rpm (3,15*60*1,995*1/1,0) This will give a normal crusing rpm between 2000 and 3000 which is quite low. Other topic is speed in 1'th gear 2 max rpm, Mine is (3,15*60*1,995*7,000/4,23) = 62,9 kmh, thats allso usable.

My primary topic is the drop in rpm form 1'th to 2'nd and to 3'rd, these are too hig hfor racing

[Adrian@]

A 1977 Taimar with which Diff?
Adrian@

[the other tim]

Adrian@ said:

A 1977 Taimar with which Diff?
Adrian@

and gearbox (ratios)

[Adrian@]

the other tim said:

and gearbox (ratios)

Aha Tim, good call, now it's a V8 ...
Adrian@

[tuscanturner]

Hi it's an lt77 gearbox on with the original Tr6 diff and axle set up. The diff carrier is the first thing to break so I might as well get the back end upgraded now.
I'm toying with putting a chimaera diff and axles on. But I'm open t opinions that won't cost half the value of the car

[tuscanturner]

Hi it's an lt77 gearbox on with the original Tr6 diff and axle set up. The diff carrier is the first thing to break so I might as well get the back end upgraded now.
I'm toying with putting a chimaera diff and axles on. But I'm open t opinions that won't cost half the value of the car

[Adrian@]

The diff carrier is a MUST modify part anyway (for a 130 BHP and 30 years old) and the 3.45 can run 220 BHP, as they were fitted in early Turbo's...as is upgraded diff frame, some new poly bushes and you could be back on the road...allow the wheels to spin rather than (don't buy into track day type tyres) grip, get it back on the road.
Adrian@
Perhaps get a shorter set of shocks for the back to stop the UJ's locking up in full droop.

[tuscanturner]

Do I need to do any hating with the standard hubs?

[bluezeeland]

Believe these are the ratios for the LT77;

1st 3.32:1
2nd 2.90:1
3rd 1.40:1
4th 1:1
5th .79:1
Reverse 3.43:1
Final Drive 3.14:1

The choice of diff is yours, but a BTR/Chimeara will require more 'adaptations' to fit then a Salisbury (which should be able to take the torque)

The Salisbury ratio closest to above, I believe, is 3.11 You might want to consider fitting a LSD, whilst at it, AV can probably sort all of this for you....

Frank

[anonymous-user]

tuscanturner said:

Do I need to do any hating with the standard hubs?

I would recommend the quaife rear hubs. You maybe luck enough to get a new set of the orignals, but refurb is supect.

[tuscanturner]

Do I need to do any hating with the standard hubs?

[madsvlund]

What Rpm range do the engine have, and what's the rear wheel size ?

You could consider a BMW M3 (E36 3,2, or E46 M3) LSD they run 3.45 or a E36 M3 3.0, that run 3.15

[tuscanturner]

Well that's now decided! Richard Good cv axles and hubs plus a Nissan R200 (skyline) LSD. Should be good for 4-500hp before the cv joints go. I think that will do and hopefully once fitted I won't need to touch it again

[Adrian@]

tuscanturner said:

Well that's now decided! Richard Good cv axles and hubs plus a Nissan R200 (skyline) LSD. Should be good for 4-500hp before the cv joints go. I think that will do and hopefully once fitted I won't need to touch it again

SO ...IF that's decided, you will need to deal with the issue of the lower wishbones and modifying the TVR uprights to allow you to fit a RG hub, build your self a frame to set the diff in, prop to suit...and limit the rear droop by a shorter shock.

I'd want to spend £50 pound on a frame upgrade and 90.00 on some poly bushes and drive/develop the car.
Adrian@

[anonymous-user]

Adrian@ said:

tuscanturner said:

Well that's now decided! Richard Good cv axles and hubs plus a Nissan R200 (skyline) LSD. Should be good for 4-500hp before the cv joints go. I think that will do and hopefully once fitted I won't need to touch it again

SO ...IF that's decided, you will need to deal with the issue of the lower wishbones and modifying the TVR uprights to allow you to fit a RG hub, build your self a frame to set the diff in, prop to suit...and limit the rear droop by a shorter shock.

I'd want to spend £50 pound on a frame upgrade and 90.00 on some poly bushes and drive/develop the car.
Adrian@

Quaife hubs would be a safe easy upgrade and ensuring UJ 's were free of grease nipples...

[tuscanturner]

The kit is for a 3000m and as my tr6 diff is screwed. Diff carrier is broken, near side driveshaft has more play in it than is safe it really needs sorting. £100 for a Nissan lsd I think it will be worth the effort. Iin addition to Adrian's comments I will also need to shorten my existing prop by 2" and I need to remember how to use the lathe and mill in the garage to do a bit of machining on the diff input flange.
Other than that Im using the tuscan As its taxed all year round. Not as much fun but still has the badge on the front.

[Adrian@]

TVRMs said:

Quaife hubs would be a safe easy upgrade and ensuring UJ 's were free of grease nipples...

In my experience, both Quaife and RG hubs require work to the hub allow the hub/CV and shaft to slide in from the outside (IMHO, this allows you to fit the assembly ready built) , I would swap the grease nipples for blanking plugs (this is related to the shock allowing the UJ's to go past their working angles) and the reason behind the shock change.
Have fun.
Adrian@

[aero340]

Another option fit a ford sierra diff !Have a pair of adaptors made up and you can still use your drive shafts depending on their condition .

[aero340]