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Spitfire & GT6 Forum

Differential

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jeffives3 Jeff Bolen
Terre Haute, IN, USA   USA
My 72 Spitfire has a 4.11-1 differential in it presently. I'm wanting to change to a 3.63-1. Any suggestions where to get one or is it better to go with a 5 speed transmission?

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Manana Avatar
Manana Steve Wten
Thornhill, ON, Canada   CAN
Jeff, welcome to the forum.

This has been discussed many many times. Try using the search function at the top of the page and if you go to advanced search you will be able to refine it nicely.

Good luck.



Steve
http://stevew10.wix.com/spit16

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
The 3.63 diff was stock in most countries outside North America, but finding one here is like finding Hens teeth.

5 speed is nice, but not really just a bolt in modification plus $$$$

Overdrive was a stock option and is very nice, but getting a good one can cost $$$$

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Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
The main cost of the 5 speed conversion is the fully rebuilt tranny they include.

Lizzard d id
san jose, CA, USA   USA
In reply to # 1512410 by Doug in Vegas The main cost of the 5 speed conversion is the fully rebuilt tranny they include.
http://www.picknpull.com/part_pricing.aspx?LocationID=46&NavItem=12&SearchCriteria=&#partpricing
400-1 Transmission Rwd (Std) Car $99.99 $29.99

If you wait for one of their 1/2 off sales . 50 bucks for a transmission . Or 80 bucks with no trade in .

clshore Carter Shore
Beverly Hills, FL, USA   USA
Spitfire 5 speed conversions come in 2 basic flavors:

1) Ford T-9 - In the US these were only used in Mercury Merkur cars.
Not so many cars were sold in the US, and of those many have been swapped out after being abused by ham handed wanna-be drag racers.

2) Toyota T-50 - These were used in Corolla, Celica, and other RWD Toyota cars for many years, and were quite plentiful and cheap at one time.
Unfortunately, the 'drift' crowd prefers RWD cars, and used these heavily, so the supply of used transmissions has all but dried up at this point.

Yes, there are other candidates, the Miata is the likely next best choice. But AFAIK, there is no 'kit' offered, and since it has the bellhousing and case
integrated as one casting, you would have to fangle a custom adaptor plate, and also handle all the other engineering details, mounts, shift linkage, clutch, etc.

Most other transmissions are simply too big and bulky to fit without major surgery.

HTH
Carter

Pats54 Avatar
Pats54 Gold Member Mark M
Maynard, Mass, USA   USA
1979 Triumph Spitfire 1500
2012 Volvo C70 "The Weekender"
I have a spare differential that I have been replacing the bearings adding a drain plug
And thinking about changing the crown and pinion gears to 3:62
You can still buy these parts new, they run about 500. For the pair
It's a wish list item for me. I am assuming that the swap can be made the. Need to read up on it.

Some of the venders offer rebuilt 3.62 for about 1500 with a core charge & shipping ( I inquired, unavailable at this time )
I think the swap of the guts is the cheapest way to go. But still need to research before I dive in.

Good luck
Mark

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Roy Avatar
Roy roy o
Marietta, GA, USA   USA
Taller tires ! I put 175-80x13 on rear , brings ratio from 3.89 to 3.6 . Dropped about 200 rpm at 70 mph .

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1512517 by Pats54 I have a spare differential that I have been replacing the bearings adding a drain plug
And thinking about changing the crown and pinion gears to 3:62
You can still buy these parts new, they run about 500. For the pair
It's a wish list item for me. I am assuming that the swap can be made the. Need to read up on it.

Some of the venders offer rebuilt 3.62 for about 1500 with a core charge & shipping ( I inquired, unavailable at this time )
I think the swap of the guts is the cheapest way to go. But still need to research before I dive in.

Good luck
Mark

There's more to it than just bolting in a new ring & pinion gearset.
They have to be 'set up' in order to operate properly, else they don't last long.
If you have never done this before, I advise doing plenty of research and reading first.
Also get a copy of the Spitfire Factory Shop Manual (try online, or CD are available)
You will also need tools and instruments, and various shims and spacers needed to set the pinion and carrier into proper mesh.
It's not rocket science, but it's really fiddly, and does require everything be done just so.
Close is 'not close enough'.
Be prepared to go through the 'check/dis-assemble/adjust/re-assemble' cycle a few times to get it right.

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Pats54 Avatar
Pats54 Gold Member Mark M
Maynard, Mass, USA   USA
1979 Triumph Spitfire 1500
2012 Volvo C70 "The Weekender"
Thank you Carter
I kind of figured it would not be as easy as it appear.

Could any one recommend a shop manual that would cover this
I have the Haynes Book and the - complete official triumph spitfire 1500 75/80
By R Bentley but I am not sure if it covers changing the pinion and crown gear.

Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
I think most of us have that too.

Rare when it's opened.

Example: I don't know if it covers the differential either.

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