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Spitfire 1500 Rear end conversion questions

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75spitfire peter p
bainbridge island, wa, USA   USA
Since this is my first post on this site let me give you a bit of background on my project. I bought my 1971 spitfire in 1988 for a $1000. The previous owner had done quite a bit of work to the car including lots of engine mods. like Webers, TR6 flat top pistons, shaved head, big valves, porting, header, ETC.. I drove the car until 1991 then it went into storage where it sat until Jan. 2012.

In Jan. of this year I was looking on Craigslist and noticed a guy close to me selling a project 1975 Spitfire. It seems he had taken the car completely apart and in the process of rebuilding it he decided to move and didn't want to take the car with him. Normally I wouldn't touch something like this as there are tons of cars out there in one piece but this car had a few bonuses. First he had bought just about every imaginable part new from Spitbits and I mean everything. Second the frame had been stripped and powdercoated. Third, the body was/is almost perfect except for a bit of rot on the rockers. Finally and possibly the best part is that the car came with a assortment of goodies from PRI. The PRI components consist of the hub adapters, front spindles, total control shock kit, and the complete brake kit for the front and rear.

My plan is to build car with a race look. Fabricate all the interior panels and dash out of aluminum. Keep it simple and as light weight as possible. So now to my question. There are a ton of ways to go with regards to the diff. and axles on a Spitfire. I know I need to rebuild the existing diff. and axles. So with this in mind I have been looking into other possibilities. There are kits from Canley, Nick Jones, ETC.. that replace the axles but that don't address the diff. There are some really fancy racing axles being made, but these too don't address the diff. Finally, a few people out there that have installed Subaru R160 diff. and axles. The R160 Is the most interesting option and I was wondering if anyone has done this modification and could lend some insight? Thank you. Pete

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MichaelB48 Avatar
MichaelB48 Michael B
Vancouver, vancouver, wa, USA   USA
Your garage is WAY too clean and big for a project like that!! I'm envious....

claytoncnc Avatar
claytoncnc Gold Member Marcus Clayton
Melbourne, Ivanhoe, Australia   AUS
Peter

I have an R160 in my spit. This one is from a Datsun 1600 (510) with the flanges. The later R180, and Subaru R160 have a single bolt fixing of shaft to axle, so the axle arrangement will change.

I welded some lugs to the back of the diff that coincide with the spit through bolt, and fabricated a front mount from some rectangular section to bolt onto the R160. Adapter flanges were fabricated for the axle, and a Datsun flange was attached to the spit prop shaft. The conversion has been in the car for 30 years, with no trouble.

I cut my spit axles and put a rotoflex in, made a bearing carrier to support the hub, and added a lower wishbone.

Are they Kirky seats you have in your car? I am just contemplating something similar.

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75spitfire peter p
bainbridge island, wa, USA   USA
Michael
Sorry the shop is so clean. Just bought it last year. Renting half of it out to RV guys to pay the taxes. Give me a year or 2 and I will have it as cluttered as my garage at home


Marcus,
Thank you for the details on your R160 that is the direction I am considering. I will fab the lower wishbone using the GT6 VL and probably keep the transverse spring. Yes those are Kirkey Vintage seats. I bought the 16" version. The Kirkey mounting brackets will not work so I will be fabricating my own mounts, to the floor and also to the rollbar. My old seats were similar but in fiberglass and worn out.

Pete

claytoncnc Avatar
claytoncnc Gold Member Marcus Clayton
Melbourne, Ivanhoe, Australia   AUS
Thanks Pete.

I am just shy of 6 feet and have not got a big arse, weighing about 90KG. Using your own frame as reference would 16 inch fit me or do you think 17 might be better?

clshore Carter Shore
Beverly Hills, Florida, USA   USA
Congratulations on your acqusitions!
Several folks have converted to R160, most using the Subaru one, since there are for more of them available than the Datsun 510 units.

A variety of ratios are available, as well as various limited slip options, viscous, clutch pack, etc.

For a Spit/GT6, there are 4 main considerations:
1) Fitting to the rear chassis mount
2) Fitting to the front two chassis mounts
3) Mounting and attachment pad for the transverse spring
4) Axle type and attachment.

Here's a link to a NZ site with some pix and a good writeup:

http://homepages.paradise.net.nz/lghrnrm/tessapg2.htm

Note that the 180 referred to was a car model, the diff itself is a Fuji Heavy Industries model R160, used in Datsun, Subaru, and other cars.
There are other larger Fuji units in the family, R180, R200, R220, etc. The number designates the diameter in mm of the crown wheel.
These can be fitted if you are willing to do chassis surgery.
But the R160 has proven to be very durable, so what's the point?

The cast aluminum rear diff plate was originally custom cast in NZ.
These were reproduced commercially in England for a short time, but no more.
Several folks in US and elsewhere have projects to reproduce the rear plate, search the web for details.

There are two styles of axle attachment used by R160 diffs.
Early models used a splined stub axle that fitted to the side gears, held in place by a center bolt.
The axles, with either UJoints or CV joints, attached to the stub axles.
Later models used a CV axle whose inner end was splined, with a lock ring, to slip directly into the side gear.

AFAIK, no one has yet installed an R160 with swing axles, due to the need for the diff to take the thrust loads from the wheels.

My advice would be to search the web, and Spitfire/GT6 sites such as this one, and contact the folks doing these projects.
They have been willing to share their plans and progress, and in some cases, there are 'group buys' in the works for castings and adaptors.

HTH,

Carter

75spitfire peter p
bainbridge island, wa, USA   USA
Marcus,
I am about the same height and weight and the 16" seems perfect. There is plenty of space on the floor for a wider seat if you decide to go that route. I actually took some scrap lumber and built a 3 sided box that had 16" measured between the sides for a test fit.

Carter,
Thank you for all the details. I found a link online for the specs for the front mounting plate. Still haven't found anything on the rear mount yet.

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Gt6s Avatar
Gt6s Laurence Cochrane
Newtownards, UK   GBR
1972 Triumph GT6 MkIII "2600 EFI"
1973 Triumph GT6 MkIII "2500"
1976 Triumph Spitfire "Sixfire 2500"
The easiest way to reinforce the diff is to fit a Quaife ATB I run one with 3.63 ratio in my fairley highley modded 2600 EFI Gt6, this has proven very strong and apart from oil changes maintenance free. The same car has alloy dash, alloy door cards 17 inch Kirkey alloy highback seat. Will soon have a second Kirkey a 4 gallon alloy fuel tank and my latest aquirement, a pair of Canley Classics aluminum rear wings and rear valance.
The last ones in captivity

Laurence

75spitfire peter p
bainbridge island, wa, USA   USA
Laurence,
I looked at installing a Quaife ATB with stronger axles and better hubs but the cost started to approach the $3K range just for the parts. I really like the idea of staying more original but unless I can find some used parts it's just too expensive.

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clshore Carter Shore
Beverly Hills, Florida, USA   USA
Laurence, glad to hear that your setup is working well.
However, most folks find that the diff has failed because the ring gear shed some teeth.

Not sure how a Quaife, or any other locking/traction split device will help with that.
Perhaps by limiting the peaks of the shockloads presented to the ring/pinion through the side axles?
But the rotoflex donuts should do a good job with that too, yet GT6+ diffs seem to be just as fragile as the rest.

Carter

Gt6s Avatar
Gt6s Laurence Cochrane
Newtownards, UK   GBR
1972 Triumph GT6 MkIII "2600 EFI"
1973 Triumph GT6 MkIII "2500"
1976 Triumph Spitfire "Sixfire 2500"
In reply to # 852809 by clshore Laurence, glad to hear that your setup is working well.
However, most folks find that the diff has failed because the ring gear shed some teeth.

Not sure how a Quaife, or any other locking/traction split device will help with that.
Perhaps by limiting the peaks of the shockloads presented to the ring/pinion through the side axles?
But the rotoflex donuts should do a good job with that too, yet GT6+ diffs seem to be just as fragile as the rest.

Carter

Carter in my experience it has almost allways been the differential carrier has exploded I run a 3.63 which is the strongest CWP Triumph built. The only exception to this was on a 3.27 which split a pinion.

Laurence



Edited 1 time(s). Last edit at 2012-11-18 01:15 PM by Gt6s.

clshore Carter Shore
Beverly Hills, Florida, USA   USA
Yah, with 2.6L of torque, that's not surprising. winking smiley

I think it would be interesting to see closeup slow motion of a Spit/GT6 diff under extreme loads.
Likely, the diff carrier, as well as the case itself, are deforming.
This would, of course, affect the mesh of the ring/pinion teeth, perhaps accounting for the tooth breakage that is commonly seen.

geeteesix Avatar
geeteesix martin diederen
kerkrade, limburg, Netherlands   NLD
I just readed your thread about the quaife modification and are very interested in your experience in this.
I drive my gt6 now for 18 years with the 2ltr engine tuned up to 158HP wich me did cost 4 complete 3.27:1 diff's. All these are exploded because of broken carriers, the other parts where never the problem so i am agree with you the only problem is the carrier. Now i am ready for a modification, i can not mention that the housing of the gt6 is too weak.
Nevertheless some people say it is better to use the housing of a spifire 1500 because it would be stronger, do you now the differences of these i do not? Furthermore racing people say it is better to take a aluminium backside housing for the diff because off it should have a better cooling and can take more oil in it, this because off the quaife takes more place so there is only e few oil in the diff then?
I would like to keep my 3.27:1 ratio because it is more comfortable when traveling on the highway, in this case people say you need a modification in the diff, do you now wich part needs the modification then(maybe the crownweel too thick?)
How many horse power has your car and how many mles you did already have experience with the quaife diff now?
Thanks in forward for you reaction in this
martin

clshore Carter Shore
Beverly Hills, Florida, USA   USA
I'm wondering now if it would be worthwhile to fab a stronger replacement carrier for the 3.27 gearset?
It would be made in one of the tough steel alloys, 4130 or such.
Only real challenge to machining it is the spherical interior surface for the planet gears.

http://www.rimmerbros.co.uk/ImagePopUp.aspx?i=GRID005732

And there are alternative designs for fitting the planet gears that eliminate the need for the spherical surface.

Carter

clshore Carter Shore
Beverly Hills, Florida, USA   USA
I was surfing around for info on the R160 rear plate casting, came accross some tantalizing links:

This one mentions a NZ firm that supplied a 'kit' (but no NAME !)

http://www.guy-croft.com/viewtopic.php?f=5&t=2669


This one discusses the NZ conversion:

http://sideways-technologies.co.uk/forums/index.php/topic/5935-subaru-datsun-differential-in-spitfire-rear-plate


Some good pix of the setup:

http://www.flickr.com/photos/66903760@N02/sets/72157627419811767/with/6092390178/


And this one actually gives a name and website in the very last entry on August 30, 2011:

http://club.triumph.org.uk/cgi-bin/forum10/Blah.pl?m-1280092897/s-all/

HTH



Edited 2 time(s). Last edit at 2012-12-30 02:44 PM by clshore.

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