Jump to content
rogerguzzi

Small Chassis Differentials

Recommended Posts

Hello All

               I am in the process of changing the Differential on the Vitesse from a 4.11 to 1(with limited slip bit in it) to a 3.63 to 1 (better for touring)

When I started to remove it I thought someone has fitted 2 short bolts instead 1 long one!

But when I looked at the parts books I realized that Triumph changed it on my Spitfire 1500!

Then I thought why? the part it fits into is the same and 2 bolts would be a better engineering solution as it clamps the crush tubes were as the long bolt does not!(cost or speed of assembly!)

Then I thought I would take the poly bush out of the old one but it looks as though it has elongated(I have had this before with the so call best ones!!!!)

So then I thought why not just make a larger diameter crush tube in stainless steel to make it round again!

What I will do is fit them in the differential and by trial and error turn the s/s so I can force the biggest diameter I can in and take up the slack plus fit the bushes turned through 180 degress

Roger

ps anyone want to buy a  4.11 to 1  Differential with a Gripper limited slip bit(could look up the build records to see how many miles it has done I know it has been back at least once for adjusting)

Share this post


Link to post
Share on other sites

Pretty sure that all Heralds and Vitesses had the twin bolts.  Not sure what is normal for Spitfires and GT6s.  The was a time when I thought it was only the swing spring cars that had the single long bolt but my roto GT6 did too.... though may not be original.

3.63 is a good ratio for a road-use Vitesse.  Gripper diff should be worth a fair bit to the right person.  I have a feeling that was a special 4.11 gearset too - does it have a round input flange or a square one?  Even my cheaper Blackline ATB diff owes me best part of £ 600 and that's just for the spool and bearings.

Share this post


Link to post
Share on other sites

All Spitfire and GT6 chassis I have seen have had the single long bolt fitting.

There is a photo in the Graham Robson book of the Earl's Court motor show Mk1 rolling chassis and engine all in white and chrome which also has the long bolt. So maybe right from the beginning.

I have a Gripper diff. Needs the later crown and pinion set as fitted to 3.89 and 3.63 Triumph diffs. And also 4.11 and 4.55 from the Morris Marina/Ital

Share this post


Link to post
Share on other sites

I presume that the long bolt was a production wheeze, like domed pistons and stamping (FRONT) on the rear spring.     It would have taken a few seconds from the assembly process.

Despite what EE says above, I agree with Roger that Triumph put crush tubes in the chassis frame, so intended two bolts at first, and never bothered to remove that detail.    The single long bolt would, IMHO, be as effective in stability terms, but probably it would have needed expensive revision of design and assembly to omit them.    I always use two bolts, as time is not critical whe rebuilding, and thr single bolt can be a bugger to get in!  Or out!

 

Share this post


Link to post
Share on other sites
22 minutes ago, JohnD said:

I agree with Roger that Triumph put crush tubes in the chassis frame, so intended two bolts at first, and never bothered to remove that detail.  

John, not sure what you mean here. The crush tube between the two rear diff mounts is there for the single long bolt but isn't there for the two single bolts arrangement. ie it was a later addition to speed up the mechanical assembly process.

Sorry folks but this bit gets a bit image heavy as we present the evidence for the defence!

I have a very early original workshop manual which shows the two bolt arrangement in the rear axle section and although the revised diff bridge is there it's not clear whether it's of a Spitfire or Herald chassis.

IMG_20200702_0001.thumb.jpg.42334195ed88ac0aa81391345f0ab913.jpg

A bit difficult to see but the drawing of the Herald and 1600 Vitesse chassis suggests there is no crush tube between the two rear mounts.

IMG_20200702_0003.thumb.jpg.6c4e6f3e5dafa17d3c520983b3bbde14.jpg

 Same with the Spitfire drawing in the same book.

IMG_20200702_0002.thumb.jpg.0e1159491ff20ed62cb9e37bf3699023.jpg

However the addendum for the Mk 3 definitely does show the crush tube between the rear mounts for the single bolt fitting

IMG_20200702_0004.thumb.jpg.c0dd0ede6764a83a47344466f8cc2ca4.jpg

Photo from the Robson book of the Mk2 Show chassis which would have been constructed for the launch clearly shows the crush tube between the mounts suggesting that there was a change on the Spitfire by the launch of the Mk2 in March 1965 at the latest.

My late Mk1 came with the single bolt and it didn't look like the chassis had been replaced.

IMG_20200702_0005.thumb.jpg.ef89efad3b8cb263e2a29c633d1b97e6.jpg

The chassis drawing for the Mk1 GT6 shows the crush tube so again a single bolt on the sports model from July 1966.

IMG_20200702_0006.thumb.jpg.ea3fbbfd8f758dd24b942f19e0c24cb6.jpg

Here is where it gets interesting though. Mk1 2 Litre Vitesse

IMG_20200702_0007.thumb.jpg.8475333183ba38467eff172378c35947.jpg

And Mk2....

IMG_20200702_0008.thumb.jpg.af11f71517bb1762ddeb9267981fcee7.jpg

So it would seem that Triumph thought they made chassis for all Heralds and Vitesses for the two bolt mounting and all Spitfires from Mk2 at least and all GT6s with the single long bolt.

Although of course knowing Triumph there's no absolute guarantee that this is what actually happened for any particular car when it left the factory or after 50 odd years of repairs and replacements.

So perhaps we are all right on this one :banana:

Share this post


Link to post
Share on other sites

Hello All

              Well what a can of worms I opened!

So yes 2 bolts with no centre tube and only one required with the centre tube.

Now the big question WHY?

Roger

Share this post


Link to post
Share on other sites

I suspect John hit it on the head when he talked about saving time/money in assembly. A long bolt and one nut is quicker to assemble than two bolts and two nuts.

As a guess it was more valuable on the sports models by this time as they were the larger production run and the idea was always to phase out the Herald in favour of the 1300. Although that took a lot longer than expected.

On a practical note I have actually found that extracting the one long bolt is easier than trying to get out the shorter bolt because you can get square on to the end of the long bolt with a drift from the side to give it a good whack and with the wheel off there is plenty of space to wield the hammer.

The short bolts you need to come in at an angle from underneath and there is a bit more dodging round the boot outriggers and floor. Less of an issue on a hoist or with a pit but not fun with the car on axle stands, outside, in the rain...

I might have been particularly lucky/unlucky here as I've never found much of a corrosion problem with the long bolt and I must have stripped about 10 different cars over the years whereas the time I had to do the job on a Vitesse one of the short bolts was a right b#####d to get out. Extracted a diff from a scrapyard Herald chassis once as well and ended up chiselling out one side of the mounting. Fortunately there was no body tub  in the way with that one.

 

Share this post


Link to post
Share on other sites

Hello All

               I have made some new crush tubes for the differential and the holes are nice and round again!

I went from 0.625" to 0.700" Dia and they just push in with some effort!

Plus I made a stand for the jack to help me refit it !

Are these brake pipe fixings in the right place? I know with the dampers off the spring goes lower but there is no mention in the WSM about easing the pipes around the spring when doing it!

Does not strike me as good engineering but I suppose Bean counters were at large again?

Roger

DSC01703.JPG

DSC01707.JPG

DSC01708.JPG

Share this post


Link to post
Share on other sites

Yes, of course no crush tube BETWEEN the mounts!

And I'm sorry, the "crush tube" is the steel tube in the bush, not part of the chassis.   Doh!

 

Share this post


Link to post
Share on other sites
2 hours ago, JohnD said:

Yes, of course no crush tube BETWEEN the mounts!

And I'm sorry, the "crush tube" is the steel tube in the bush, not part of the chassis.   Doh!

:thumbsup: been there, got that T shirt mate!

Roger. That looks very 'pro'.

The brake lines are correct. Once the diff is back in and the spring lifted up there is enough space (just) for the hose. This one is not as nice as yours.

2014-10-17-11_54.13-1024x768.thumb.jpg.646412f2c02df4bbd28434b680a4c022.jpg

On the later Spitfires the outboard end of the hose was moved from going directly into the brake cylinder to connect with a short length of hard pipe that went to the cylinder.

Presumably Triumph eventually had the same thought as you regards all getting a bit tight in there.

I did the same on my Mk1 because with the shortened uprights it really was too tight.

20200504_134639.thumb.jpg.116277986496278f96d5f8a20f75417f.jpg

Share this post


Link to post
Share on other sites

Hello Escadrille Ecosse (you must have a shorter name?)

                                                                                                               Yes my Spitfire 1500 is different I think I will look at changing as I do not like it(waste of time I know but that's me!)

Plus  I think they had claims from dealers when brake hoses were cut/damaged!(not sure about mine now!)

Roger

Share this post


Link to post
Share on other sites

I have had a few 1200 coupes (nz market) with the single long bolt. I think I may also have had some 1200 sedans with the same but I cannot remember clearly. 

Share this post


Link to post
Share on other sites
3 hours ago, rustbuckit2011 said:

I have had a few 1200 coupes (nz market) with the single long bolt. I think I may also have had some 1200 sedans with the same but I cannot remember clearly. 

Why would things be simple!

13 hours ago, rogerguzzi said:

Hello Escadrille Ecosse (you must have a shorter name?)

Colin :biggrin:

Share this post


Link to post
Share on other sites

I suppose that Colin didn't want to use "Ecurie Ecosse", probably best known for its iconic car transporter

1920px-Ecurie_Ecosse_Car_Transporter.jpg

but such a well known and respected team that the name has been revived, more than once.

Share this post


Link to post
Share on other sites

JohnD LOL. yes just that so came up with Escadrille Ecosse as a pun on the Ecurie Ecosse name and that it's a Spitfire.

And rather cheekily got some of these made up for the car...

DSC00163.thumb.JPG.f436b4d92d6d7986d10db913187745ab.JPG

They will be going back on the rebuilt car too.

That is a cracking photo of the original EE transporter John. AH Sprite, Lotus 11 and is that a C Type at the back?

After you posted that I had to go and have a rake in the cupboard to find this. Christmas 1965 from Santa. 4 years old. Start 'em young!

20200704_105716.thumb.jpg.c444afc08e41baac02f36a01c1b51b78.jpg

Colin

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...