Jump to content

Speedo cable - LT230 to Series 3 speedo


FridgeFreezer
 Share

Recommended Posts

I want to keep my S3 speedo despite having an LT230 transfer box, can anyone tell me if I can get a cable or assembly of cables that will let me do this? I know some are 2-part cables which would presumably give the ability to mix ends?

Also are there different ratio speedo drives for the LT230, and if so does anyone know the ratios/part #s?

Link to comment
Share on other sites

was thinking about the ratio issues a few days ago <_< got a 14D suffix A here which hopefully soon I will pull apart and can figure out what that ratio is, if I get a chance soon I'll look at the Series items and see what ratio the speedo drive is to set as a base-line :)

Link to comment
Share on other sites

I've worked out my gearing is closest to an early 110 with 1.6:1 LT230 and 7.50's so would that be frc3313 red / 24 tooth drive gear (lowest of them all) I'm guessing.

Mind you it depends on what the speedo is too so does anyone know what the differences are / ratios they use? I'm hoping that a S3 LWB speedo may share gearing with an early 110 speedo :unsure: not holding my breath though.

Link to comment
Share on other sites

I've worked out my gearing is closest to an early 110 with 1.6:1 LT230 and 7.50's so would that be frc3313 red / 24 tooth drive gear (lowest of them all) I'm guessing.

Mind you it depends on what the speedo is too so does anyone know what the differences are / ratios they use? I'm hoping that a S3 LWB speedo may share gearing with an early 110 speedo :unsure: not holding my breath though.

Fridge, i run a normal series 3 speedo cable with the lt230, just remove the 3 holed retaining washer, then just clamp it with the LT cable retaing fork, it will fit. I run an 1.003 lt230, 4.7diffs with a lwb speedo and my speedo is pretty spot on( + or - 5mph), but i run small tyres 31". I left the same speedo gear inside the TC that went with the rangie speedo. In fact i was amazed at how close the speedo was for the mixed drive train and tyres i have. Seems to work pretty well for a first try.

Give it a try and then check how accurate you are with another vehicle, mine varied from vehicle to vehicle, i guess that everybody gets different results with different tyres, and i have no gps to really verify accuracy.

Grem

Link to comment
Share on other sites

I've worked out my gearing is closest to an early 110 with 1.6:1 LT230 and 7.50's so would that be frc3313 red / 24 tooth drive gear (lowest of them all) I'm guessing.

Mind you it depends on what the speedo is too so does anyone know what the differences are / ratios they use? I'm hoping that a S3 LWB speedo may share gearing with an early 110 speedo :unsure: not holding my breath though.

The ratio in the transfer case (1.003, 1.222 et cetera) won't affect the speedo readout as it is up-stream of the speedo drive. As the speedo drive is on the output shaft, ala Series TC as well, only the teeth numbers on the speedo drive worm and screw determine the speedo drive ratio, and then the axle ratio with tyre size determining what the speedo ratio needs to be.

However interesting that the 1.003 RRC box speedo drive gives an accurate read-out for tyres that are 31" (7.50~, with 235/85 being close to 31.7"~), 4.7 diffs and a LWB speedo, good news for me, but possibly not for you John as it will depend on the final drive ratios in your axles :unsure:

Link to comment
Share on other sites

I found that a RRC speedo head indicated correctly when I fitted 3.54 diff's to my IIA (standard Series transmission). IIRC, the red (FRC3313) gear is standard for a RRC on 205s. Therefore the standard Series speedo drive pinion must be equivalent to a red gear as both vehicles were set for 205R16 tyres. This suggests you could retain the standard S3 speedo so long as you are still running 4.7 diff's.

Minivin: The 1.003 transfer box should read accurately as this would normally be set for 205 tyres. The differences in tyre size of a Series vehicle were accommodated in the gearing of the speedo head. A LWB speedo head would be fine for 31" tyres.

Link to comment
Share on other sites

I found that a RRC speedo head indicated correctly when I fitted 3.54 diff's to my IIA (standard Series transmission). IIRC, the red (FRC3313) gear is standard for a RRC on 205s. Therefore the standard Series speedo drive pinion must be equivalent to a red gear as both vehicles were set for 205R16 tyres. This suggests you could retain the standard S3 speedo so long as you are still running 4.7 diff's.

Minivin: The 1.003 transfer box should read accurately as this would normally be set for 205 tyres. The differences in tyre size of a Series vehicle were accommodated in the gearing of the speedo head. A LWB speedo head would be fine for 31" tyres.

Aiy, knew about the speedo head being a factor in the game of things, it was something that was lurking in the back of my mind a few weeks back on whether the swapping of speedo's would assist as well..... and then something came up and it got put aside :)

Link to comment
Share on other sites

Fridge, i run a normal series 3 speedo cable with the lt230, just remove the 3 holed retaining washer, then just clamp it with the LT cable retaing fork, it will fit. I run an 1.003 lt230, 4.7diffs with a lwb speedo and my speedo is pretty spot on( + or - 5mph), but i run small tyres 31". I left the same speedo gear inside the TC that went with the rangie speedo. In fact i was amazed at how close the speedo was for the mixed drive train and tyres i have. Seems to work pretty well for a first try.

Grem

I can confirm this - I used a series speedo and cable with a rangie transmission on my hybrid. Not sure what the drive gear was, but it read bang on with 33" tyres. (well, as bang on as a series speedo will read....)

Link to comment
Share on other sites

Ok, I have just examined a Series Transfer Case speedo drive and it is as follows:

Screw: Five Start

Worm: 11T

Ratio: 2.2:1

So with a diff. ratio of 4.71:1, the speedo ratio that the speedo head sees is 10.362:1 or 10.362 revolutions of the speedo drive worm gear, per single revolution of the rear wheel.

However, that's superfluous as IIRC all you need is a 2.2:1 ratio on the LT230 speedo drive to get the same affect as a series TC when only changing the Series TC and GB for an LT77/R380 and LT230 :)

Link to comment
Share on other sites

This from a man who promotes and builds megasquirt? Why all this mechanical malarky? :blink:

Seal the speedo drive up at the gearbox, put in a Sat Nav unit!

Or (one that I am going to be asking you about very soon!) road speed transducer and let MS do it?

It's because I don't have sat nav / GPS but I do have a speedo head and it's one less thing to do to get the truck on the road. Also the speedo is mechanical so can go in the normal place as the rest of the dash (EG anything electric) is going at head height.

Link to comment
Share on other sites

Just lash it together with whatever you have got then have it calibrated, simple as :P

Now that's what I did when I built a rev counter for my classic motorcycle, as I used some speedo bits to make the drive and then got a very helpful Chronometric speedo person down West Sussex to build a rev counter to my requirements...... anybody know of a speedo person who does speedos ala Land Rover?

Link to comment
Share on other sites

ok, I have just torn the 14D...A 1.003 LT230 apart and have come up with the following:

Screw: 9 start

Worm: 20T

Ratio 2.222(reoccurring):1

Therefore in theory the speedo would think you were driving 1.01% slower and as the speedo always seems to read grossly over when ever I compare it to the GPS (75mph indicated compared to 68mph actual on one test), it would bring the speedo marginally closer to what your actual speed is, if retaining standard tyres et cetera.

However, I do not know at present whether other LT230's use a different screw gear with the other worm gears, so something to possibly find out and see which gears can be swapped for different ratios?

Link to comment
Share on other sites

EPC shows the speedo gear [worm] is FRC3162 a common part in all LT230's hope that helps

:D

excellentay, another datum to work from :i-m_so_happy:

One thing I did find while comparing a 2WD R380 to a LT230 is that the drive gear on the 2WD R380 is splined for engaging on the mainshaft ie positively located, while the LT230 is a plain slide fit on the output shaft, so it's dependent on being clamped on by the output flange retention nut pressure. Why couldn't British Leyland keep stuff simple <_<

Link to comment
Share on other sites

oh, and LT230 speedo drive gears are machined so that they come out at 90 degrees to the output shaft, while a R380 2WD speedo drive comes out at about 60 degrees to the mainshaft, so you can't use the bits from a 2WD to do speedo change work :rolleyes:

Link to comment
Share on other sites

  • 7 years later...

Hi,

I have the same problem, but I would like to know how I can find the best ratio. Can you explain how to do it?

Data:

  • S3 Speedmoter from a 109,
  • LT 230 from a discovery
  • Diff: 3.54
  • Tyres: 7.50

Which ratio fits the better?

Thanks

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy