XR4 Gearbox IB5+ Issues

Diddi · 04-10-2020, 09:17 PM

Hi, recently purchased a 2008 WQ XR4 for my daughter as she wanted to learn to drive in a manual.

Joined this forum hoping to get some information on gearbox options. Gearbox jumps out of 2nd gear when decelerating and crunches when going into 3rd. Gearbox oil replaced with Penrite PRO GEAR 75W-90 Full Synthetic, which did improve the 3rd gear crunch somewhat.

The only alternative appears to be the MTX75 gearbox, but have not been able to find a kit to facilitate/enable the swap out, and it appears some of the frame has to be cut away to fit the MTX75, so I'm not sure how I'd go in regards to engineering certification.

It appears the only other options are a sequential IB5+ out of England, which would probably cost more than what I paid for the car, or have the current unit rebuilt.

Q1) Is there any other workable and stronger alternative to replace the IB5+?

Q2) Can the IB5+ gearbox be built stronger, and if so what are the parts I need and where can I purchase them from?

Q3) Apparently the diff is a weak point. Recommendations for a good quality replacement Limited Slip Diff which would improve handling?
I'm not sure if the information is correct, but I have been told some LSD's can turn a FWD vehicle into an under-steering pig.

Q4) Recommendations for someone who can rebuild the IB5+ stronger? I'm in Tamworth NSW and would be happy to drive as far as somewhere like Newcastle, or alternatively have the box removed and shipped to whoever does the rebuild best.

The XR4 is great little car and reminds me in many ways of my Mini Cooper S when I was a teenager. It would be great if I could sort it for her.

**russellw** · 07-10-2020, 09:27 AM

The MTX75 does require quite substantial modifications to fit it into the Fiesta and I suspect you'd struggle to get compliance here.

The IB5 isn't a bad gearbox but it's designed for reasonably light duty work and is known for wearing out the synchros if subjected to punishment. Replacing those will probably fix both symptoms you have now and might be all that is required.

The B6 is a stronger unit as fitted to the later ST models and apparently is a reasonably simple swap but they might be hard to find here.

There are also kits with stronger internals (like the ERST ones) that include bigger bearings and better synchro rings but you'll probably need to source them out of the UK.

Unless you plan to race it, give the LSD a miss.

**Luke Plaizier** · 08-10-2020, 08:07 PM

The IB5+ weak point is the diff bearings - there's some kind of plastic component in the bearing that is known to fail. Replace that with metal and the IB5+ can handle much more power than the initial factory rating. But if you're opening it up for bearings, whipping in an LSD would seem like an easy add-on. The down side is the cost, as you'd likely need to get the LSD shipped from the UK. There are groups on Facebook you could venture in to ask - in Australia there's the XR4 Australia Owners and the XR4 Register. In the UK there's a few Mk6 groups and an ST150 group.

The IB6 6 speed from later fisters will have bell housing patterns for the Sigma engine though, so would be a good swap for a 1.6 Fister, but not the Mazda L series 2.0 engine, which is why the IB5+ is so unique.

For a gearbox rebuild, there's a place in Newcastle called 'Newcastle Gearbox and Diff' that could possible do the work you seek. I've had them rebuild the diff on my 2003 XR8 and was happy with their workmanship.

As for the MTX75, I'm part the way through that process, but as I'm more of a computer nerd the electronic stuff has more of an allure at the moment.

**Luke Plaizier** · 08-10-2020, 08:34 PM

I thought the IB5+ weak point was the diff bearings - there's some kind of plastic component in the bearing that is known to fail. Replace that with metal and the IB5+ can handle much more power than the initial factory rating apparently. But if you're opening it up for bearings, whipping in an LSD would seem like an easy add-on - albeit expensive, as you'd likely need to get the LSD shipped from the UK. There are groups on Facebook you could venture in to ask - in Australia there's the XR4 Australia Owners and the XR4 Register. In the UK there's a few Mk6 groups and an ST150 group.

The IB6 6 speed from later fisters will have the bell housing pattern for the Sigma engine though, so would be a good swap for a 1.6 Fister, but not the Mazda L series 2.0 engine, which is why the IB5+ is so unique.

For a gearbox rebuild, there's a place in Newcastle called 'Newcastle Gearbox and Diff' that could possibly do the work you seek. I've had them rebuild the diff on my 2003 XR8 and was happy with their workmanship.

As for the MTX75, I'm part the way through that process, but as I'm more of a computer nerd the electronic stuff has more of an allure at the moment. I'll get there eventually.

Lukeyson

**Luke Plaizier** · 08-10-2020, 08:35 PM

I'm copping a few duplicate posts lately, and not even clicking buttons twice. not sure what is going on.

Lukeyson

zabatron · 10-10-2020, 05:26 PM

I bought a WQ Fiesta XR4 brand new back in 2008.It had the 3rd gear crunch issue from new, most noticeable when shifting down to 3rd gear,and it jumped out of 2nd gear when decelerating a few times as well,also from new.Of course the Ford dealer's response was that it was normal, and "they all do it.
Anyway,these issues got a lot worse,along with the cold shift performance, at@30,000km,when an inspection of the gearbox oil found it to be black, smelly and very much burnt.I replaced the gearbox oil first with the genuine Ford gearbox fluid, then with the same Penrite Pro Gear 75w/90gear oil as recommended on the Penrite Website,but the above issues remained, and the cold shift performance was very ordinary with both of these oils.Note this was around 10 years ago,so both of these gearbox fluids may have been reformulated since then.and may work better today than they did 10 years ago.
But from my own personal experience the best gearbox fluid by far for the Getrag/Ford IB5+ gearbox used in the XR4 is Castrol Syntrans 75w/85 as it cured all the above issues in my XR4,and shifted perfecly both hot or cold until I sold the car at 90000km about 4 years ago.
If it was me,I would change the gearbox fluid before changing out gearboxes.

TICKFORD220 · 22-08-2024, 10:18 AM

Quote:

Originally Posted by zabatron

I bought a WQ Fiesta XR4 brand new back in 2008.It had the 3rd gear crunch issue from new, most noticeable when shifting down to 3rd gear,and it jumped out of 2nd gear when decelerating a few times as well,also from new.Of course the Ford dealer's response was that it was normal, and "they all do it.
Anyway,these issues got a lot worse,along with the cold shift performance, at@30,000km,when an inspection of the gearbox oil found it to be black, smelly and very much burnt.I replaced the gearbox oil first with the genuine Ford gearbox fluid, then with the same Penrite Pro Gear 75w/90gear oil as recommended on the Penrite Website,but the above issues remained, and the cold shift performance was very ordinary with both of these oils.Note this was around 10 years ago,so both of these gearbox fluids may have been reformulated since then.and may work better today than they did 10 years ago.
But from my own personal experience the best gearbox fluid by far for the Getrag/Ford IB5+ gearbox used in the XR4 is Castrol Syntrans 75w/85 as it cured all the above issues in my XR4,and shifted perfecly both hot or cold until I sold the car at 90000km about 4 years ago.
If it was me,I would change the gearbox fluid before changing out gearboxes.

I know this post is 4 years old but a big thanks to Zabatron
My 2004 fiesta lx has had shifting issues when cold since i got it a couple months ago.
Whatever oil was in it when purchased had issues especially 1st to 2nd crunching.
Changed to penrite gl4 and it was even worse,saw this post pop up and after running the castrol 75/ 85 for a week it feels amazing,its actually a joy to drive.
Saved me a big headache finding the right oil.
Thankyou

Tom2 · 22-10-2020, 02:41 PM

This sounds like the gearbox mount is gone. You can buy a new vibra tecnics mount which should sovle the problem. https://www.burtonpower.com/vibra-te...ibfor620m.html That's the link to the mount. you may as well replace the other 2 while your at it. Also incase you are unaware the easiest way to find parts for these cars is to search for Fiesta ST 150.