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#1 Malbaby

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Posted 10 August 2018 - 11:01 PM

Does anyone know if a Lexus IS200 diff can easily be adapted to TR4A.


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#2 stuart

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Posted 11 August 2018 - 03:06 PM

Why would you want to?

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#3 had17462

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Posted 12 August 2018 - 02:53 PM

Stuart I put in a Nissan diff with the goodparts conversion kit ,very good upgrade.
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#4 stillp

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Posted 12 August 2018 - 03:05 PM

very good upgrade.
 

Why?

 

Pete


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#5 Z320

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Posted 12 August 2018 - 05:17 PM

+ ?
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#6 Hamish

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Posted 12 August 2018 - 06:18 PM

Probably because the Lexus IS200 diff is an LSD type. Is my guess.
H
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#7 Malbaby

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Posted 12 August 2018 - 09:46 PM

The Lexus diff looks similar to the Nissan R200, which is sometimes used as an upgrade from a worn factory diff.


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#8 Z320

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Posted 13 August 2018 - 05:37 AM

Hi ?,

 

at eBay Germany there is one for a very nice price.

https://www.ebay.de/...3fffd4db9|iid:1

 

From the photo I see:

 

- the incoming shaft / prop shaft is in the center between the front brackets, if ths fits you will need 2 different long drive shafts

- front brackets are cast iron on the cast iron diff housing, if that fits it's OK, if not you have a challange

- rear brackets could be less a problem if the housing is shorter than the TR diff housing

- info found by Gooogle it seems to me there are different gear ratios, all longer than for the TR

 

My advice: buy it and find out (for yourself and us).

 

Ciao Marco


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#9 Z320

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Posted 13 August 2018 - 05:42 AM

Sorry: shorter gesr ratio, your TR becomes slower

(to edit my post does not work?)
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#10 stuart

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Posted 13 August 2018 - 09:22 AM

Stuart I put in a Nissan diff with the goodparts conversion kit ,very good upgrade.
Nick

Thats been a known conversion kit for quite a few years from an SX200 and one or two members on here have used it, I was commenting on the Lexus version as I have never seen anyone use that type and as they have been around for quite a while there must be some problem that makes them unsuitable

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#11 Rockie51

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Posted 13 August 2018 - 10:18 PM

You haven't said why you want to change the differential Malcolm. If it is a wear problem, you can still buy new crown wheel and pinion sets from diff specialists. I had mine done some years ago and it was not very expensive. I believe that the parts came from Italy. Bearings are always available and a diff specialist should be able to set it up for you. Much less work than changing to a diff from another make with potential problems with driveshafts and different ratios. Unlike other cars that you and I have, I doubt that a TR will ever produce the sort of power that will require a limited slip diff!

 

If you are wanting to change ratios, fitting 185/15 tyres will give a 7% increase in gearing, the same as swapping to the 3.45 diff fitted to the TR6


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#12 Z320

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Posted 14 August 2018 - 06:17 AM

Hi,

 

I drive a 1:3,7 diff and 185/15 tyres on my TR4A - but no overdrive.

Early this year I got an offer to buy a 1:3,45 diff and I thought this would be a nice idea instead a overdrive.

But went to Italy with this idea in mind across the alps and stick in bad traffic on the german autobahn and around Lago Maggiore.

And realised: the gear ration of 1:3,7 (with the tyres) is already to long city traffic and Stau. Bad idea to fit a 1:3,45 ratio.

 

Cioa Marco


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#13 BlueTR3A-5EKT

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Posted 14 August 2018 - 07:50 AM

Hi,

 

I drive a 1:3,7 diff and 185/15 tyres on my TR4A - but no overdrive.

Early this year I got an offer to buy a 1:3,45 diff and I thought this would be a nice idea instead a overdrive.

But went to Italy with this idea in mind across the alps and stick in bad traffic on the german autobahn and around Lago Maggiore.

And realised: the gear ration of 1:3,7 (with the tyres) is already to long city traffic and Stau. Bad idea to fit a 1:3,45 ratio.

 

Cioa Marco

Off Topic.

I toyed with using a 3.45-1 TR5/6 ratio in the TR3A in place of the 3.7 - 1 standard item.  There are many who have done this in their 4 cylinder TR's and are quite happy with the outcome.

As my engine is a bit 'cammy' I concluded I would be continually in 2nd or 3rd when driving in town.  This does not say I have killed the idea as I like the idea of reduced engine RPM when motorway driving. Problem comes when you drive at that sweet RPM of 3500 in overdrive top.... 

My other concern was the first gear ratio, as my car has the Dolomite Sprint/late Stag gear set, which has same first gear ratio as post 1973 TR6. (2.19 to 1)

 

Peter W

 

PS Car has 165*80x15 tyres on TR6 5 1/5J steel rims and A type overdrive.


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#14 Z320

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Posted 14 August 2018 - 08:43 AM

What I wanted to say is:

 

you can not use a diff from another car that looks "suitable" without knowing its gear ration

and without having an idea what ratio you want to have - and why.


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#15 TriumphV8

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Posted 14 August 2018 - 09:26 AM

I am building a new rear drive with a BMW diff.

Project sticks because actually all is working well

but I am close to finish. -no bigger problems-

 

Reasons are:

Widely availiable and cheap

All ratios from 2.3 to 4.1 and further for motorsport

Fully without play and rock solid

Smaller width and flanges to accept CV-joints with no adaptors

Allows longer driveshafts to reduce angle to bend under load.

 

I am just rebuilding the driveshafts with BMW or VW inside and Nissan outside.

Driveshaft itself is nearly 50% longer than with the other CV swaps.

 

Lexus parts are used in my opinion because they are more common in USA.

 

It is not an easy job to swap but not that big deal.

A lathe, a milling machine and good welding equipment is required.


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Cheers

Andreas


#16 Z320

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Posted 14 August 2018 - 10:04 AM

Hi Andreas,

"not an easy Job but not a big deal" is relativ, don't forget you are a "10" :)  

Ciao Marco


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#17 stuart

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Posted 14 August 2018 - 10:40 AM

How do you get these modifications past the TUV Andreas?

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#18 TriumphV8

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Posted 14 August 2018 - 10:42 AM

Many thanks Marco but it is indeed not that complicated.

Diff front pulley redrilled,

rear casing from 40mm aluminium milled and TR4a back bolted.

Front 5mm steel plate cut out and holder for the two rubber made

on the lathe, all welded together.

 

Thats is all for the diff, cv-joints that fit is a bit more work.

But when I read about all that trouble british people have

with refurbished TR diffs it is relatively nice work.


Edited by TriumphV8, 14 August 2018 - 10:49 AM.

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Cheers

Andreas


#19 TriumphV8

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Posted 14 August 2018 - 10:48 AM

Hi Stuart last time at the TÜV I only had the cv axles and

the engineer did not find it necessary to examine.

 

You are right, in these days it will be a big problem

with these modifications because material quality must

be shown with the invoice and welding must be done

by a certified expert. -Both I do not have-

That is a weak point in the whole project.

 

But that will be no difference compared to the Lexus project.

Some parts can be bought from Goodparts and the diff itself

might be a bit more difficult to obtain and maybe the ratio will

not be perfect. -So like often, all effort spent on these will be similar-


Edited by TriumphV8, 14 August 2018 - 10:51 AM.

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Cheers

Andreas


#20 Malbaby

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Posted 14 August 2018 - 10:56 PM

Andreas...what model BMW is your diff from, and what ratio.

Also, can you post more info on the driveshafts...pics and details.....Thanks in advance.


Edited by Malbaby, 14 August 2018 - 10:57 PM.

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